MAIZE REPLICATION PROTEIN A

Abstract: Methods and compositions for modulating DNA metabolism are provided. Nucleotide and amino acid sequences encoding a maize replication protein A subunit are provided. The sequences can be used in expression cassettes for modulating DNA replication, DNA repair, and recombination.

Description: MAIZE REPLICATION PROTEIN A FIELD OF THE INVENTION The invention relates to the genetic manipulation of plants, particularly to modulating DNA metabolism in transformed plants and plant cells BACKGROUND OF THE INVENTION Replication protein A (RPA) is a single-stranded DNA-binding protein that is required for multiple processes in eukaryotic cells RPA from human cells is a stable complex of 70-, 32-, and 14-kDa subunits Homologues of RPA have been identified in all eukaryotes examined However, only human RPA and closely related homologues can support SV40 DNA replication The RPA complex appears to be highly conserved in all eukaryotes The three RPA genes in budding yeast cells are essential for cell viability Nevertheless, yeast RPA only partially substitutes for human RPA in the in vitro replication of simian virus 40 indicating that species-specific interactions between RPA and other replication proteins may be important for its biological activity RPA binds tightly to single stranded DNA as a heterotrimeric complex The binding activity has been localized to the 70 kDa subunit The affinity of RPA for both double-stranded DNA and RNA is at least three orders of magnitude lower than it is for single-stranded DNA It has been reported that RPA binds preferentially to the pyrimidine-rich strand of both S. cerevisiae sequences and the SV40 origin of replication However, studies examining the determinants of replication origins in S. cerevisiae indicate that this preferential binding is not critical for the initiation of DNA replication Subunits of RPA in the 70-, 32- and 14 kDa ranges have been identified from various sources The 32kDa subunit has also been referred to as "RPA2", "B", "small", "32kDa", "P32", "P34", and "middle" subunit For the purposes of this invention, the "middle" subunit is intended as the subunit having a molecular weight of about 32 kDa The middle subunit of RPA has a role in cell cycle regulation, single stranded DNA binding, affinity of DNA binding, species-specificity of DNA binding, DNA recombination, repair, replication and metabolism, and response to DNA damages (Anderson (1966) Calif. Inst. Technol, Seroussi et al (1993) J. Biol. Chem. 268 7147-54, Kenny et al (1989) Proc. Natl. Acad Sci. USA 86 9757- 61, Brush et al (1995) Methods Enzymol. 262 522-48, Stigger et α/ (1994) Proc. Natl. Acad. Sci. USA 91 579-83, Philipova et al (1996) Genes Dev. 10 2222-33) Much research has centered on the exploration of the biochemical and genetic mechanisms by which cell cycle regulation of DNA synthesis is achieved While there have been advances in delineating the existence of cell cycle proteins, more information is needed on the mechanism of action of DNA replication, recombination, and repair Furthermore, methods for regulating or altering the cell cycle is needed Related Literature Braun et al (1997) Biochemistry 36 8443-8454, report on the role of protein-protein interactions and the function of replication protein A It is reported that RPA modulates the activity of DNA polymerase α by multiple mechanisms Loor et al (1997) Nucleic Acids Research 25 5041-5046 report on the identification of DNA replication in cell cycle proteins that interact with proliferating cell nuclear antigen Longhese et l (1994) Molecular and Cellular Biology 14 7884-7890 report that replication factor A is required for in vivo DNA replication, repair, and recombination Stigger et al (1998) J. Biol. Chem. 273 9337-9343 provide a functional analysis of human replication protein A in nucleotide excision repair Abremova et l (1997) Proc. Natl. Acad. Sci. USA 94 1186-7191 report that the interaction between replication protein A and p53 is disrupted after ultraviolet damage in a DNA repair-dependent manner New et al (1998) Nature 391 407-410 reports that RAD52 protein stimulates DNA strand exchange by RAD51 and replication protein A Stimulation was dependent on the concerted action of both RAD51 protein and RPA implying that specific protein-protein interactions between RAD52 protein, RAD51 protein and RPA are required Dutta et α/ (\992) EMBO J 11(6) 2189-2199 and Niu et al. (1997) J. Biol. Chem. 272(19) 12634-41 report cell cycle-dependent phosphorylation of the middle subunit of RPA, implying a role for the subunit in cell cycle regulation Bochkareva et al (1998) J. Biol. Chem. 273(7) 3932-3936 report the formation of a single stranded DNA binding site on the human RPA middle subunit Mass et α/ (1998) Mol. Cell. Biol. 18(11) 6399-6407 report that the RPA middle subunit contacts nascent simian virus 40 DNA, particularly the early DNA chain intermediates synthesized by DNA polymerase alpha-primase (RNA-DNA primers), but not more advanced products Lavrik et al (1998) Nucleic Acids Res 26(2) 602-607 report on location of binding of individual subunits of human RPA to DNA primer-template complexes in various elongation reactions Sibenaller et al (1998) 37(36) 12496-12506 report that differences in the activity of the middle (32kDa) and the small (14 Kda) subunits of RPA are responsible for variations in the single stranded DNA-binding properties of sacchromyces cerevisiae and human RPA, thus implying a role for the subunits in species-specificity of DNA binding of RPA SUMMARY OF THE INVENTION Compositions and methods for modulating DNA metabolism in a host cell is provided Particularly, the complete cDNA and amino acid sequence for homologues of maize replication protein A (RPA) large- and middle subunits are provided The sequences of the invention find use in modulating DNA replication, DNA repair, and recombination Transformed plants can be obtained having altered metabolic states The invention has implications in genetic transformation and gene targeting in plants Additionally, the methods can be used to promote cell death particularly in an inducible or tissue-preferred manner BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 provides a comparison of eukaryotic RPA large subunit amino acid sequences Amino acid sequences for the RPA large subunits/ro/w Sacchromyces Cerevisiae (Rfal Yeast, SEQ ID NO 10), Schizosacchromyces pombe (Rfal Schpo, SEQ ID NO 9), Drosophila melanogaster (Rfal Drome, SEQ ID NO 8 , Homo sapiens (Rfal Human, SEQ ID NO 7), Xenopus laevis (Rfa_Xenla, SEQ ID NO 6), and Oryza sativa (024183, SEQ ID NO 5) were compared with the maize RPA LS homologue 1 (ZMRPALSHl, SEQ ID NO 2) and homologue 2 (ZMRPALSH2, SEQ ID NO 4) using the GCG PileUp program utilizing default parameters. The putative zinc finger region is shown in italics Figure 2 provides an expression construct for inducible expression of the maize RPA large or middle subunit antisense construct DETAILED DESCRIPTION OF THE INVENTION Nucleotide sequences and proteins useful for modulating DNA metabolism are provided The nucleotide and amino acid sequences correspond to the maize replication protein A (RPA) subunits RPA is a single-stranded DNA-binding protein that is required for multiple processes in DNA metabolism, including DNA replication, DNA repair, and recombination The RPA complex generally comprises subunits of approximately 70, 32, and 14 kDa By "large subunit", "middle subunit", and "small subunit" is herein intended a RPA subunit having the approximate molecular weight of 70-, 32-, and 14 kDa respectively The sequences of the invention comprise the large- and middle subunits of the RPA complex The sequences of the invention additionally find use in modulating gene expression Compositions of the invention include RPA nucleotide and amino acid sequences that are involved in modulating DNA metabolism In particular, the present invention provides for isolated nucleic acid molecules comprising nucleotide sequences encoding the amino acid sequences shown in SEQ ID NOs 2 and 4 for the large subunit, and SEQ ID NOs 12, 14, 16, 18, 20, and 22 for the middle subunit SEQ ID NO 2 and SEQ ID NO 4 correspond to the amino acid sequences for the maize RPA large subunit homologue 1 (ZmRPALSHl) and homologue 2 (ZmRPALSH2) SEQ ID NOs. 12, 14, 16, 18, 20, and 22 correspond to the amino acid sequences for the maize middle subunit homologue 1 (ZmRPAMSHl), homologues 2 and 3 (ZmRPAMSH2 and ZmRPAMSH3), homologue 4 (ZmRPAMSH4), homologue 5 (ZmRPAMSH5), homologue 6 (ZmRPAMSHό), and homologue 7 (ZmRPAMSH7) respectively For the large subunit, the present invention alternatively provides the nucleotide sequences encoding the DNA sequences deposited in a bacterial host as Patent Deposit Nos 98754 and 98843 For the large subunits, further are polypeptides having an amino acid sequence encoded by a nucleic acid molecule described herein, for example those set forth in SEQ ID NOs 1 and 3, those deposited in a bacterial host as Patent Deposit Nos 98754 and 98843, and fragments and variants thereof Plasmids containing the RPA large subunit nucleotide sequences of the invention were deposited with the Patent Depository of the American Type Culture Collection (ATCC), Manassas, Virginia, and assigned Patent Deposit NOs 98754 and 98843 These deposits will be maintained under the terms of the Budapest Treaty on the International Recognition of the Deposit of Microorganisms for the Purposes of Patent Procedure These deposits were made merely as a convenience for those of skill in the art and are not an admission that a deposit is required under 35 U S C §112 Nucleotide sequences encoding the amino acid sequences for the maize RPA large subunit homologue 1 (ZmRPALSHl) and homologue 2 (ZmRPALSH2) are set forth in SEQ ID NOs 1 and 3 Nucleotide sequences encoding the amino acid sequences for the maize RPA middle subunit homologue 1 (ZmRPAMSHl), homologues 2 and 3 (ZmRPAMSH2 and ZmRPAMSH3), homologue 4 (ZmRPAMSH4), homologue 5 (ZmRPAMSH5), homologue 6 (ZmRPAMSHό), and homologue 7 (ZmRPAMSH7) are set forth in SEQ ID NOs 1 1, 13, 15, 17, 19, and 21 respectively The invention encompasses isolated or substantially purified nucleic acid or protein compositions An "isolated" or "purified" nucleic acid molecule or protein, or biologically active portion thereof, is substantially free of other cellular material, or culture medium when produced by recombinant techniques, or substantially free of chemical precursors or other chemicals when chemically synthesized Preferably, an "isolated" nucleic acid is free of sequences (preferably protein encoding sequences) that naturally flank the nucleic acid (i e , sequences located at the 5' and 3' ends of the nucleic acid) in the genomic DNA of the organism from which the nucleic acid is derived For example, in various embodiments, the isolated nucleic acid molecule can contain less than about 5 kb, 4 kb, 3 kb, 2 kb, 1 kb, 0 5 kb, or 0 1 kb of nucleotide sequences that naturally flank the nucleic acid molecule in genomic DNA of the cell from which the nucleic acid is derived A protein that is substantially free of cellular material includes preparations of protein having less than about 30%, 20%, 10%, 5%, (by dry weight) of contaminating protein When the protein of the invention or biologically active portion thereof is recombinantly produced, preferably culture medium represents less than about 30%, 20%), 10%), or 5%> (by dry weight) of chemical precursors or non-protein-of- interest chemicals RPA binds tightly to single-stranded DNA (ssDNA) The affinity of binding to double-stranded DNA (dsDNA) is three to four orders of magnitude lower than the binding affinity for ssDNA Because RPA has been found to bind specifically to certain dsDNA sequences that seem to be involved in the regulation of transcription, modulation of gene expression may be affected by an increase or decrease in RPA expression in the host cell RPA has a wide range of activity and therefore uses relating to DNA metabolism and cell cycle RPA interacts specifically with several proteins required for nucleotide excision repair Interactions with repair proteins indicate that RPA may be important for efficient damage recognition and cleavage RPA additionally interacts with RAD52 protein, a protein that is essential for dsDNA- break repair This interaction appears to be essential for homologous recombination In this manner, expression of the nucleotides of the invention may promote homologous recombination by recruiting factors which are essential for recombination to occur Thus, the methods and compositions of the invention find use in promoting homologous recombination In one embodiment, genetic manipulation by homologous recombination can be improved by either expression of the RPA coding sequences of the invention during transformation, or by providing RPA protein RPA protein, for example, may be provided as a coating to particles duπng particle bombardment Alternatively, DNA constructs providing for the expression of RPA may be included with the DNA to be transformed The increase in RPA during transformation, particularly integration of polynucleotides by homologous recombination, promotes integration and insertion of the DNA sequences of interest into the plant genome In the same manner, it may be beneficial to inhibit the expression or presence of the RPA protein to encourage non-specific recombination events. In this manner, antibodies, peptides, antisense oligonucleotides and the like may be utilized to inhibit the activity of RPA Alternatively, antisense constructs may be provided to inhibit the expression of RPA and encourage non-specific recombination Catalytic RNA molecules or ribozymes can also be used to inhibit expression of plant genes It is possible to design ribozymes that specifically pair with virtually any target RNA and cleave the phosphodiester backbone at a specific location, thereby functionally inactivating the target RNA In carrying out this cleavage, the ribozyme is not itself altered, and is thus capable of recycling and cleaving other molecules, making it a true enzyme The inclusion of ribozyme sequences within antisense RNAs confers RNA-cleaving activity upon them, thereby increasing the activity of the constructs The design and use of target RNA-specific ribozymes is described in Haseloff et al (1988) Nature 334 585-591 A variety of cross-linking agents, alkylating agents and radical generating species as pendant groups on polynucleotides of the present invention can be used to bind, label, detect, and/or cleave nucleic acids For example, Vlassov, V V et al (1986) Nucleic Acids Res. 14 4065-4076, describe covalent bonding of a single- stranded DNA fragment with alkylating derivatives of nucleotides complementary to target sequences A report of similar work by the same group is that by Knorre et al (1985) Biochimie 67 785-789 Iverson and Dervan also showed sequence-specific cleavage of single-stranded DNA mediated by incorporation of a modified nucleotide which was capable of activating cleavage (1987) J. Am. Chem. Soc. 109 1241-1243) Meyer et al (1989) J. Am. Chem. Soc. Ill 8517-8519, effect covalent crosslinking to a target nucleotide using an alkylating agent complementary to the single-stranded target nucleotide sequence A photoactivated crosslinking to single-stranded oligonucleotides mediated by psoralen was disclosed by Lee et al (1988) Biochem. 27 3197-3203 Use of crosslinking in triple-helix forming probes was also disclosed by Home et al 1 (1990) J. Am. Chem. Soc. 112 2435-2437 Use of N4, N4-ethanocytosine as an alkylating agent to crosslink to single-stranded oligonucleotides has also been described by Webb et al (1986) J Am. Chem. Soc. 108 2764-2765, Webb et al (1986) Nucleic Acids Res. 14 7661-7674, Feteritz et al (1991) J. Am. Chem. Soc. 113 4000 Various compounds to bind, detect, label, and/or cleave nucleic acids are known in the art See, for example, U S Patent Nos 5,543,507, 5,672,593, 5,484,908, 5,256,648, and 5,681,941 RPA is required for the replication of chromosomal DNA Inhibition of endogenous RPA expression is deleterious to the cell, organism, or plant Thus, the constructs of the invention can be used to selectively kill target cells or tissues This can be accomplished through the use of inducible or tissue-preferred promoters In this manner, the sequences of the invention may find use in enhancing pathogen resistance An antisense construct for the RPA coding sequence is operably linked to a pathogen-inducible promoter Upon contact with the pathogen, the RPA antisense construct is expressed resulting in cell death and effectively preventing the invasion of the pathogen The invention is drawn to compositions and methods for inducing resistance in a plant to plant pests Accordingly, the compositions and methods are also useful in protecting plants against fungal pathogens, viruses, nematodes, insects and the like By "disease resistance" is intended that the plants avoid the disease symptoms that are the outcome of plant-pathogen interactions That is, pathogens are prevented from causing plant diseases and the associated disease symptoms, or alternatively, the disease symptoms caused by the pathogen is minimized or lessened The methods of the invention can be utilized to protect plants from disease, particularly those diseases that are caused by plant pathogens Pathogens of the invention include, but are not limited to, viruses or viroids, bacteria, insects, nematodes, fungi, and the like Viruses include any plant virus, for example, tobacco or cucumber mosaic virus, ringspot virus, necrosis virus, maize dwarf mosaic virus, etc Specific fungal and viral pathogens for the major crops include Soybeans Phytophthora megasperma fsp glycinea, Macrophomina phaseohna, Rhizoctonia solani, Sclerotinia sclerotiorum, Fusarium oxysporum, Diaporthe phaseolorum var sojae (Phomopsis sojae), Diaporthe phaseolorum var caulivora, Sclerotium rolfsu, Cercospora kikuchii, Cercospora sojina, Peronospora manshurica, Colletotrichum dematmm (Colletotichum truncatum), Corynespora cassucola, Septoria glycines, Phyllosticta sojicola, Alter naria alternata, Pseudomonas syringae p v glycinea, Xanthomonas campestris p v phaseoh, Microsphaera diffusa, Fusarium semitectum, Phialophora gregata, Soybean mosaic virus, Glomerella glycines, Tobacco Ring spot virus, Tobacco Streak virus, Phakopsora pachyrhizi, Pythium aphanidermatum, Pythium ultimum, Pythium debaryanum, Tomato spotted wilt virus, Heterodera glycines Fusarium solani, Canola Albugo Candida, Alternaria brassicae, Leptosphaeria maculans, Rhizoctonia solani, Sclerotinia sclerotiorum, Mycosphaerella brassiccola, Pythium ultimum, Peronospora par asitica, Fusarium roseum, Alternaria alternata, Alfalfa Clavώater michiganese subsp. insidiosum, Pythium ultimum, Pythium irregulare, Pythium splendens, Pythium debaryanum, Pythium aphanidermatum, Phytophthora megasperma, Peronospora trifoliorum, Phoma medicaginis var medicaginis, Cercospora medicaginis, Pseudopeziza medicaginis, Leptotrochda medicaginis, Fusarium, Xanthomonas campestris p v alfalfae, Aphanomyces euteiches, Stemphylium herbarum, Slemphyhum alfalfae, Wheat Pseudomonas syringae p v atrofaciens, Urocystis agropyri, Xanthomonas campestris p v translucens, Pseudomonas syringae p v syringae, Alternaria alternata, Cladosporium herbarum, Fusarium graminearum, Fusarium avenaceum, Fusarium culmorum, Ustilago tritici, Ascochyta tritici, Cephalosporium gramineum, Collotetrichum graminicola, Erysψhe graminis f sp tritici, Puccinia graminis f sp tritici, Puccinia recondita f sp tritici, Puccima strnformis, Pyrenophora tritici-repentis, Septoria nodorum, Septoria tritici, Septoria avenae, Pseudocercosporella herpotrichoides, Rhizoctonia solani, Rhizoctonia cerealis, Gaeumannomyces graminis var tritici, Pythium aphanidermatum, Pythium arrhenomanes, Pythium ultimum, Bipolaris sorokiniana, Barley Yellow Dwarf Virus, Brome Mosaic Virus, Soil Borne Wheat Mosaic Virus, Wheat Streak Mosaic Virus, Wheat Spindle Streak Virus, American Wheat Striate Virus, Claviceps purpurea, Tilletia tritici, Tilletia laevis, Ustilago tritici, Tilletia indica, Rhizoctonia solani, Pythium arrhenomannes, Pythium gramicola, Pythium aphanidermatum, High Plains Virus, European wheat striate virus, Sunflower Plasmophora halstedn, Sclerotinia sclerotiorum, Aster Yellows, Septoria hehanthi, Phomopsis hehanthi, Alternaria hehanthi, Alternaria zinniae, Botrytis cinerea, Phoma macdonaldii, Macrophomina phaseohna, Erysψhe cichoracearum, Rhizopus oryzae, Rhizopus arrhizus, Rhizopus stolonifer, Puccinia hehanthi, Verticύlium dah ae, Erwinia carotovorum pv carotovora, Cephalosporium acremonium, Phytophthora cryptogea, Albugo tragopogoms; Corn Fusarium momliforme var subglutinans, Erwinia stewartn, Fusarium monihforme, Gibber ella zeae (Fusarium graminearum), Stenocarpella maydi (Dψlodia maydis), Pythium irregulare, Pythium debaryanum, Pythium graminicola, Pythium splendens, Pythium ultimum, Pythium aphanidermatum, Aspergillus flavus, Bipolaris maydis O, T (Cochhobolus heterostrophus) , Helmmthosporium carbonum I, II & III (Cochhobolus carbonum), Exserohύum turcicum I, II & III, Helmmthosporium pedicellatum, Physoderma maydis, Phyllosticta maydis, Kabatiella maydis, Cercospora sorghi, Ustilago maydis, Puccinia sorghi, Puccinia polysora, Macrophomina phaseohna, Penicillium oxalicum, Nigrospora oryzae, Cladosporium herbarum, Curvularia lunata, Curvularia maequahs, Curvularia pallescens, Clavibacter michiganense subsp nebraskense, Trichoderma viride, Maize Dwarf Mosaic Virus A & B, Wheat Streak Mosaic Virus, Maize Chlorotic Dwarf Virus, Claviceps sorghi, Pseudonomas avenae, Erwinia chrysanthemi pv zea, Erwinia carotovora, Corn stunt spiroplasma, Diplodta macrospora, Sclerophthora macrospora, Peronosclerospora sorghi, Peronosclerosporaphi ppinensis, Peronosclerospora maydis, Peronosclerospora sacchari, Sphacelotheca reiliana, Physopella zeae, Cephalosporium maydis, Cephalosporium acremonium, Maize Chlorotic Mottle Virus, High Plains Virus, Maize Mosaic Virus, Maize Rayado Fino Virus, Maize Streak Virus, Maize Stripe Virus, Maize Rough Dwarf Virus, Sorghum Exserohilum turcicum, Colletotrichum graminicola (Glomerella graminicola), Cercospora sorghi, Gloeocercospora sorghi, Ascochyta sorghma, Pseudomonas syringae p v syringae, Xanthomonas campestris p v holcicola, Pseudomonas andropogoms, Puccinia purpurea, Macrophomina phaseohna, Per coma circinata, Fusarium monihforme, Alternaria alternata, Bipolaris sorghicola, Helmmthosporium sorghicola, Curvularia lunata, Phoma insidiosa, Pseudomonas avenae (Pseudomonas alboprecψitans) , Ramu spora sorghi, Ramuhspora sorghicola, Phyllachara sacchari, Sporisorium reilianum (Sphacelotheca reiliana), Sphacelotheca cruenta, Sporisorium sorghi, Sugarcane mosaic H, Maize Dwarf Mosaic Virus A & B, Claviceps sorghi, Rhizoctonia solani, Acremonium strictum, Sclerophthona macrospora, Peronosclerospora sorghi, Peronosclerospora phihppinensis, Sclerospora graminicola, Fusarium graminearum, Fusarium oxysporum, Pythium arrhenomanes, Pythium graminicola, etc Nematodes include parasitic nematodes such as root-knot, cyst, and lesion nematodes, including Heterodera and Globodera spp; particularly Globodera rostochiensis and globodera paihda (potato cyst nematodes), Heterodera glycines (soybean cyst nematode), Heterodera schachtn (beet cyst nematode), and Heterodera avenae (cereal cyst nematode) Insect pests include insects selected from the orders Coleoptera, Diptera, Hymenoptera, Lepidoptera, Mallophaga, Homoptera, Hemiptera, Orthoptera, Thysanoptera, Dermaptera, Isoptera, Anoplura, Siphonaptera, Trichoptera, etc , particularly Coleoptera and Lepidoptera Insect pests of the invention for the major crops include Maize Ostrinia nubύalis, European corn borer, Agrotis ipsύon, black cutworm, Helicoverpa zea, corn earworm, Spodoptera frugiperda, fall armyworm, Diatraea grandiosella, southwestern corn borer, Elasmopalpus hgnosellus, lesser cornstalk borer, Diatraea saccharalis, surgarcane borer, Diabrotica virgifera, western corn rootworm, Diabrotica longicornis barberi, northern corn rootworm, Diabrotica undecimpunctata howardi, southern corn rootworm, Melanotus spp., wireworms, Cyclocephala boreahs, northern masked chafer (white grub), Cyclocephala immaculata, southern masked chafer (white grub), Popil a japomca, Japanese beetle, Chaetocnema pu caria, corn flea beetle, Sphenophorus maidis, maize billbug, Rhopalosψhum maidis, corn leaf aphid, Anuraphis maidiradicis, corn root aphid, Blissus leucopterus leucopterus, chinch bug, Melanoplus femurrubrum, redlegged grasshopper, Melanoplus sanguimpes, migratory grasshopper, Hylemya platura, seedcorn maggot, Agromyza parvicornis, corn blot leafminer, Anaphothrips obscrurus, grass thrips, Solenopsis milesta, thief ant, Tetranychus urticae, twospotted spider mite, Sorghum Chilo partellus, sorghum borer, Spodoptera frugiperda, fall armyworm, Helicoverpa zea, corn earworm, Elasmopalpus hgnosellus, lesser cornstalk borer, Feltia subterranea, granulate cutworm, Phyllophaga crinita, white grub, Eleodes, Conoderus, and Aeolus spp., wireworms, Oulema melanopus, cereal leaf beetle, Chaetocnema puhcaria, corn flea beetle, Sphenophorus maidis, maize billbug, Rhopalosψhum maidis, corn leaf aphid, Sipha lava, yellow sugarcane aphid, Blissus leucopterus leucopterus, chinch bug, Contarmia sorghicola, sorghum midge, Tetranychus cinnabarmus, carmine spider mite, Tetranychus urticae, twospotted spider mite, Wheat Pseudaletia umpunctata, army worm, Spodoptera frugiperda, fall armyworm, Elasmopalpus hgnosellus, lesser cornstalk borer, Agrotis orthogonia, western cutworm, Elasmopalpus hgnosellus, lesser cornstalk borer, Oulema melanopus, cereal leaf beetle, Hypera punctata, clover leaf weevil, Diabrotica undecimpunctata howardi, southern corn rootworm, Russian wheat aphid, Schizaphis graminum, greenbug, Macrosiphum avenae, English grain aphid, Melanoplus femurrubrum, redlegged grasshopper, Melanoplus differentialis, differential grasshopper, Melanoplus sanguimpes, migratory grasshopper, Mayetiola destructor, Hessian fly, Sitodiplosis mosellana, wheat midge, Meromyza americana, wheat stem maggot, Hylemya coarctata, wheat bulb fly, Frankliniella fusca, tobacco thrips, Cephus cinctus, wheat stem sawfly, Aceria tulipae, wheat curl mite, Sunflower Suleima helianthana, sunflower bud moth, Homoeosoma electellum, sunflower moth, zygogramma exclamatioms, sunflower beetle, Bothyrus gibbosus, carrot beetle, Neolaswptera murtfeldtiana, sunflower seed midge, Cotton Hehothis virescens, cotton budworm, Helicoverpa zea, cotton bollworm, Spodoptera exigua, beet armyworm, Pectinophora gossypiella, pink bollworm, Anthonomus grandis grandis, boll weevil, Aphis gossypu, cotton aphid, Pseudatomoscelis seriatus, cotton fleahopper, Trialeurodes abutύonea, bandedwinged whitefly, Lygus hneolaris, tarnished plant bug, Melanoplus femurrubrum, redlegged grasshopper, Melanoplus differentialis, differential grasshopper, Thrips tabaci, onion thrips, Frankhnkiella fusca, tobacco thrips, Tetranychus cinnabarmus, carmine spider mite, Tetranychus urticae, twospotted spider mite, Rice Diatraea saccharalis, sugarcane borer, Spodoptera frugiperda, fall armyworm, Helicoverpa zea, corn earworm, Colaspis brunnea, grape colaspis, Lissorhoptrus oryzophilus, rice water weevil, Sitophilus oryzae, rice weevil, Nephotettix nigropictus, rice leafhopper, Blissus leucopterus leucopterus, chinch bug, Acrosternum hilare, green stink bug, Soybean Pseudoplusia includens, soybean looper, Anticarsia gemmatahs, velvetbean caterpillar, Plathypena scabra, green cloverworm, Ostrinia nubila s, European corn borer, Agrotis ipsilon, black cutworm, Spodoptera exigua, beet armyworm, Hehothis virescens, cotton budworm, Helicoverpa zea, cotton bollworm, Epilachna varivestis, Mexican bean beetle, Myzus persicae, green peach aphid, Empoascafabae, potato leafhopper, Acrosternum hilare, green stink bug, Melanoplus femurrubrum, redlegged grasshopper, Melanoplus differentialis, differential grasshopper, Hylemya platura, seedcorn maggot, Sericothrips variabilis, soybean thrips, Thrips tabaci, onion thrips, Tetranychus turkestani, strawberry spider mite, Tetranychus urticae, twospotted spider mite, Barley Ostrinia nubilahs, European corn borer, Agrotis ipsilon, black cutworm, Schizaphis graminum, greenbug, Blissus leucopterus leucopterus, chinch bug, Acrosternum hilare, green stink bug, Euschistus servus, brown stink bug, Delia platura, seedcorn maggot, Mayetiola destructor, Hessian fly, Petrobia latens, brown wheat mite, Oil Seed Rape Brevicoryne brassicae, cabbage aphid, Phyllotreta cruciferae, Flea beetle, Mamestra configurata, Bertha armyworm, Plutella xylostella, Diamond-back moth, Delia ssp , Root maggots A number of promoters can be used in the practice of the invention The promoters can be selected based on the desired outcome The nucleic acids can be combined with constitutive, tissue-preferred, or other promoters for expression in plants A plant promoter can be employed which will direct expression of a polynucleotide of the present invention in all tissues of a regenerated plant Such promoters are referred to herein as "constitutive" promoters and are active under most environmental conditions and states of development or cell differentiation Such constitutive promoters include, for example, the core promoter of the Rsyn7 (WO 99/43838), the core CaMV 35S promoter (Odell et al. (1985) Nature 313 810-812), rice actin (McElroy et α/. (1990) Plant Cell 2 163-171), ubiquitin (Christensen et al. (1989) Plant Mol. Biol. 12 619-632 and Christensen et al. (1992) Plant Mol. Biol. 18 675-689), pEMU (Last et al. (1991) Theor. Appl. Genet. 81 581-588), MAS (Velten et al. (1984) £MBO J 3 2723-2730), ALS promoter (U S Patent No 5,659,026), and the like Other constitutive promoters include, for example, U S Patent Nos 5,608,149, 5,608,144, 5,604,121, 5,569,597, 5,466,785, 5,399,680, 5,268,463, and 5,608,142 Alternatively, the plant promoter can direct expression of a polynucleotide of present invention in a specific tissue or may be otherwise under more precise environmental or developmental control Such promoters are referred to here as "inducible" promoters Environmental conditions that may effect transcription by inducible promoters include pathogen attack, anaerobic conditions, or the presence of light Examples of inducible promoters are the Adhl promoter which is inducible by hypoxia or cold stress, the Hsp70 promoter which is inducible by heat stress, and the PPDK promoter which is inducible by light Examples of promoters under developmental control include promoters that initiate transcription only, or preferentially, in certain tissues, such as leaves, roots, fruit, seeds, or flowers An exemplary promoter is the anther specific promoter 5126 (U S Patent Nos 5,689,049 and 5,689,051) The operation of a promoter may also vary depending on its location in the genome Thus, an inducible promoter may become fully or partially constitutive in certain locations The promoters can be selected based on the desired outcome When the genes are expressed at levels to cause cell death, an inducible promoter or tissue specific promoters can be used to drive the expression of the genes of the invention The inducible promoter must be tightly regulated to prevent unnecessary cell death, yet be expressed in the presence of a pathogen to prevent infection and disease symptoms Generally, it will be beneficial to express the gene from an inducible promoter, particularly from a pathogen-inducible promoter Such promoters include those from pathogenesis-related proteins (PR proteins), which are induced following infection by a pathogen, e g , PR proteins, SAR proteins, beta-l,3-glucanase, chitinase, etc See, for example, Redolfi et al. (1983) Neth. J. Plant Pathol. 89 245-254, Uknes et al. (1992) Plant Cell 4 645-656, and Van Loon (1985) Plant Mol. Virol. 4 111-1 16 See also the copending application entitled "Inducible Maize Promoters", U S Application Serial No 09/257,583, filed February 25, 1999, herein incorporated by reference Of interest are promoters that are expressed locally at or near the site of pathogen infection See, for example, Marineau et al. (1987) Plant Mol. Biol. 9 335-342, Matton et al. (1989) Molecular Plant-Microbe Interactions 2 325-331 , Somsisch et al. (1986) Proc. Natl. Acad. Sci. USA 83 2427-2430, Somsisch et al. (1988) o/. Gen. Genet. 2 93-98, and Yang (1996) Proc. Natl. Acad. Sci. USA 93 14972-14977 See also, Chen et al. (1996) Plant J. 10 955-966, Zhang et al (1994) Proc. Natl. Acad. Sci. USA 91 2507-2511, Warner et al. (\993) Plant J. 3 191-201, Siebertz et α/. (1989) Plant Cell 7.961-968, U S Patent No 5,750,386 (nematode-inducible), and the references cited therein Of particular interest is the inducible promoter for the maize PRms gene, whose expression is induced by the pathogen Fusarium monihforme (see, for example, Cordero et al. (1992) Physiol. Mol. Plant Path. 41 189-200) Additionally, as pathogens find entry into plants through wounds or insect damage, a wound-inducible promoter may be used in the constructions of the invention Such wound-inducible promoters include potato proteinase inhibitor (pin II) gene (Ryan ( 1990) Ann. Rev. Phytopath. 28 425-449, Duan et al. ( 1996) Nature Biotechnology 14 494-498), wunl and wun2, US Patent No 5,428, 148, winl and win2 (Stanford et al (1989) Mol. Gen. Genet. 215 200-208), systemin (McGurl et al. (1992) Science 225 1570-1573), WIP1 (Rohmeier et al (1993) Plant Mol. Biol. 22 783-792, Eckelkamp et al (1993) FEBS Letters 323 73-76), MPI gene (Corderok et al (1994) Plant J. 6(2) 141-150), and the like, herein incorporated by reference Chemical-regulated promoters can be used to modulate the expression of a gene in a plant through the application of an exogenous chemical regulator Depending upon the objective, the promoter may be a chemical-inducible promoter, where application of the chemical induces gene expression, or a chemical-repressible promoter, where application of the chemical represses gene expression Chemical-inducible promoters are known in the art and include, but are not limited to, the maize In2-2 promoter, which is activated by benzenesulfonamide herbicide safeners, the maize GST promoter, which is activated by hydrophobic electrophilic compounds that are used as pre-emergent herbicides, and the tobacco PR- la promoter, which is activated by salicylic acid Other chemical-regulated promoters of interest include steroid-responsive promoters (see, for example, the glucocorticoid-inducible promoter in Schena et al (1991) Proc. Natl. Acad Sci. USA 88 10421-10425 and McNellis et al (1998) Plant J 14(2) 247-257) and tetracycline-inducible and tetracycline-repressible promoters (see, for example, Gatz et al (1991) Mol. Gen. Genet 227 229-237, and U S Patent Nos 5,814,618 and 5,789,156), herein incorporated by reference Where low level expression is desired, weak promoters will be used Generally, by "weak promoter" is intended a promoter that drives expression of a coding sequence at a low level By low level is intended at levels of about 1/1000 transcripts to about 1/100,000 transcripts to about 1/500,000 transcripts. Alternatively, it is recognized that weak promoters also encompasses promoters that are expressed in only a few cells and not in others to give a total low level of expression Where a promoter is expressed at unacceptably high levels, portions of the promoter sequence can be deleted or modified to decrease expression levels Such weak constitutive promoters include, for example, the core promoter of the Rsyn7 (WO 99/43838), the core 35 S CaMV promoter, and the like Other constitutive promoters include, for example, U S Patent Nos 5,608, 149, 5,608,144, 5,604, 121, 5,569,597, 5,466,785, 5,399,680, 5,268,463, and 5,608,142 See also, the copending application entitled "Constitutive Maize Promoters", U S Application Serial No 09/257,584, filed February 25, 1999, and herein incorporated by reference Tissue-preferred promoters can be utilized to target enhanced RPA expression within a particular plant tissue In this aspect of the invention, the antisense constructs are useful for tissue-preferred expression Male or female sterility may be affected by use of the antisense constructs with tissue-preferred promoters Although not a limitation, of particular interest are promoters for male sterility For example, the anther-preferred promoter 5126 can be used See, for example, U S Patent Nos 5,689,049 and 5,689,051, herein incorporated by reference Tissue-preferred promoters include Yamamoto et al (1997) Plant J. 12(2)255-265, Kawamata et al. (1997) Plant Cell Physiol. 38(7) 792-803, Hansen et al. (1997) Mol. Gen Genet. 254(3) 337-343, Russell et al. (1997) Transgenic Res. 6(2) 157-168, Rinehart et α/ (1996) Plant Physiol 112(3) 1331-1341, Van Camp et α/. (1996) Plant Physio 112(2) 525-535, Canevascini et al (1996) Plant Physiol. 112(2) 513-524, Yamamoto et al (1994) Plant Cell Physiol. 35(5) 773- 778, Lam (1994) Results Probl. Cell Differ. 20 181-196, Orozco et al (1993) Plant Mol Biol. 23(6) 1129-1138, Matsuoka et al (1993) Proc Natl. Acad. Sci. USA 90(20) 9586-9590, and Guevara-Garcia et al (1993) Plant J. 4(3) 495-505 Such promoters can be modified, if necessary, for weak expression Leaf-specific promoters are known in the art See, for example, Yamamoto et al. (1997) Plant. I. 12(2) 255-265, Kwon et al (1994) Plant Physiol 105 351- 67, Yamamoto et al. (1994) Plant Cell Physiol. 35(5) 773-778, Gotor et al (1993) Plant J. 3 509-18, Orozco et al. (\993) Plant Mol. Biol. 23(6) 1129-1138, and Matsuoka et al. (1993) Proc. Natl Acad Sci. USA 90(20) 9586-9590 Root-specific promoters are known and can be selected from the many available from the literature or isolated de novo from various compatible species See, for example, Hire et al. (1992) Plant Mol. Biol. 20(2) 207-218 (soybean root- specific glutamine synthetase gene), Keller and Baumgartner (1991) Plant Cell 3(10) 1051-1061 (root-specific control element in the GRP 1 8 gene of French bean), Sanger et α/ (1990) Plant Mol. Biol. 14(3) 433-443 (root-specific promoter of the mannopine synthase (MAS) gene of Agrobacterium tumefaciens), and Miao et al (1991) Plant Cell 3(1) 11-22 (full-length cDNA clone encoding cytosolic glutamine synthetase (GS), which is expressed in roots and root nodules of soybean) See also Bogusz et al (1990) Plant Cell 2(7) 633-641, where two root- specific promoters isolated from hemoglobin genes from the nitrogen-fixing nonlegume Parasponia andersonu and the related non-nitrogen-fixing nonlegume Trema tomentosa are described The promoters of these genes were linked to a β- glucuronidase reporter gene and introduced into both the nonlegume Nicotiana tabacum and the legume Lotus corniculatus, and in both instances root-specific promoter activity was preserved Leach and Aoyagi (1991) describe their analysis of the promoters of the highly expressed rolC and rolD root-inducing genes of Agrobacterium rhizogenes (see Plant Science (Limerick) 79(1) 69-76) They concluded that enhancer and tissue-preferred DNA determinants are dissociated in those promoters Teeri et α/ (1989) used gene fusion to lacZ to show that the Agrobacterium T-DNA gene encoding octopine synthase is especially active in the epidermis of the root tip and that the TR2' gene is root specific in the intact plant and stimulated by wounding in leaf tissue, an especially desirable combination of characteristics for use with an insecticidal or larvicidal gene (see EMBO J. 8(2) 343-350) The TRI' gene, fused to nptll (neomycin phosphotransferase II) showed similar characteristics Additional root-preferred promoters include the VfENOD-GRP3 gene promoter (Kuster et al. (1995) Plant Mol. Biol. 29(4) 759- 772), and rolB promoter (Capana et al. (1994) Plant Mol. Biol. 25(4) 681-691 See also U S Patent Nos 5,837,876, 5,750,386, 5,633,363, 5,459,252, 5,401,836, 5, 110,732, and 5,023,179 "Seed-preferred" promoters include both "seed-specific" promoters (those promoters active during seed development such as promoters of seed storage proteins) as well as "seed-germinating" promoters (those promoters active during seed germination) See Thompson et al (1989) BwEssays 10 108, herein incorporated by reference Such seed-preferred promoters include, but are not limited to, Ciml (cytokinin-induced message), cZ19Bl (maize 19 kDa zein), milps (myo-inositol-1 -phosphate synthase), and eel A (cellulose synthase) (see the copending application entitled "Seed-Preferred Promoters," U S Application Serial No 60/097,233, filed August 20, 1998, herein incorporated by reference. Gama-zein is a preferred endosperm-specific promoter Glob-1 is a preferred embryo-specific promoter For dicots, seed-specific promoters include, but are not limited to, bean β-phaseolin, napin, β-conglycinin, soybean lectin, cruciferin, and the like For monocots, seed-specific promoters include, but are not limited to, maize 15 kDa zein, 22 kDa zein, 27 kDa zein, g-zein, waxy, shrunken 1, shrunken 2, globulin 1, etc Both heterologous and non-heterologous (i e , endogenous) promoters can be employed to direct expression of the nucleic acids of the present invention These promoters can also be used, for example, in recombinant expression cassettes to drive expression of antisense nucleic acids to reduce, increase, or alter RPA content and/or composition in a desired tissue, or to generate sterile plants Optionally, RPA nucleic acids from a variety of sources, as discussed above can be employed to create male sterile plants In optional embodiments, the RPA gene or cDNA is operably linked to an anther-specific promoter such as 5126, as discussed above Preferably, the male sterile plant is maize Thus, in some embodiments, the nucleic acid construct will comprise a promoter functional in a plant cell, such as in Zea mays, operably linked to a polynucleotide of the present invention Promoters useful in these embodiments include the endogenous promoters driving expression of a polypeptide of the present invention In some embodiments, isolated nucleic acids which serve as promoter or enhancer elements can be introduced in the appropriate position (generally upstream) of a non-heterologous form of a polynucleotide of the present invention so as to up or down regulate expression of a polynucleotide of the present invention For example, endogenous promoters can be altered in vivo by mutation, deletion, and/or substitution (see, Kmiec, U S Patent No 5,565,350, Zarling et al , PCT/US93/03868), or isolated promoters can be introduced into a plant cell in the proper orientation and distance from a RPA gene so as to control the expression of the gene Gene expression can be modulated under conditions suitable for plant growth so as to alter RPA content and/or composition Thus, the present invention provides compositions, and methods for making, heterologous promoters and/or enhancers operably linked to a native, endogenous (i e , non-heterologous) form of a polynucleotide of the present invention Methods for identifying promoters with a particular expression pattern, in terms of e g , tissue type, cell type, stage of development, and/or environmental conditions, are well known in the art See, e g , The Maize Handbook, Chapters 1 14-1 15, Freeling and Walbot, eds , Springer, New York (1994), Corn and Corn Improvement, 3 rd edition, Chapter 6, Sprague and Dudley, eds , American Society of Agronomy, Madison, Wisconsin (1988) A typical step in promoter isolation methods is identification of gene products that are expressed with some degree of specificity in the target tissue Amongst the range of methodologies are differential hybridization to cDNA libraries, subtractive hybridization, differential display, differential 2-D protein gel electrophoresis, DNA probe arrays, and isolation of proteins known to be expressed with some specificity in the target tissue Such methods are well known to those of skill in the art Commercially available products for identifying promoters are known in the art such as Clontech's (Palo Alto, CA) Universal GenomeWalker Kit For the protein-based methods, it is helpful to obtain the amino acid sequence for at least a portion of the identified protein, and then to use the protein sequence as the basis for preparing a nucleic acid that can be used as a probe to identify either genomic DNA directly, or preferably, to identify a cDNA clone from a library prepared from the target tissue Once such a cDNA clone has been identified, that sequence can be used to identify the sequence at the 5' end of the transcript of the indicated gene For differential hybridization, subtractive hybridization and differential display, the nucleic acid sequence identified as enriched in the target tissue is used to identify the sequence at the 5' end of the transcript of the indicated gene Once such sequences are identified, starting either from protein sequences or nucleic acid sequences, any of these sequences identified as being from the gene transcript can be used to screen a genomic library prepared from the target organism Methods for identifying and confirming the transcriptional start site are well known in the art In the process of isolating promoters expressed under particular environmental conditions or stresses, or in specific tissues, or at particular developmental stages, a number of genes are identified that are expressed under the desired circumstances, in the desired tissue, or at the desired stage Further analysis will reveal expression of each particular gene in one or more other tissues of the plant One can identify a promoter with activity in the desired tissue or condition but that do not have activity in any other common tissue To identify the promoter sequence, the 5' portions of the clones described here are analyzed for sequences characteristic of promoter sequences For instance, promoter sequence elements include the TATA box consensus sequence (TATAAT), which is usually an AT-rich stretch of 5-10 bp located approximately 20 to 40 base pairs upstream of the transcription start site Identification of the TATA box is well known in the art For example, one way to predict the location of this element is to identify the transcription start site using standard RNA-mapping techniques such as primer extension, SI analysis, and/or RNase protection To confirm the presence of the AT-rich sequence, a structure-function analysis can be performed involving mutagenesis of the putative region and quantification of the mutation's effect on expression of a linked downstream reporter gene See, e g , The Maize Handbook, Chapter 114, Freeling and Walbot, eds , Springer, New York (1994) In plants, further upstream from the TATA box, at positions -80 to -100, there is typically a promoter element (i e , the CAAT box) with a series of adenines surrounding the trinucleotide G (or T) N G J Messing et al , in Genetic Engineering in Plants, Kosage, Meredith and Hollaender, eds , pp 221-227 (1983) In maize, there no well-conserved CAAT box but there are several short, conserved protein-binding motifs upstream of the TATA box These include motifs for the transacting transcription factors involved in light regulation, anaerobic induction, hormonal regulation, or anthocyanin biosynthesis, as appropriate for each gene Once promoter and/or gene sequences are known, a region of suitable size is selected from the genomic DNA that is 5' to the transcriptional start, or the translational start site, and such sequences are then linked to a coding sequence If the transcriptional start site is used as the point of fusion, any of a number of possible 5' untranslated regions can be used in between the transcriptional start site and the partial coding sequence If the translational start site at the 3' end of the specific promoter is used, then it is linked directly to the methionine start codon of a coding sequence If polypeptide expression is desired, it is generally desirable to include apolyadenylation region at the 3 '-end of a polynucleotide coding region The polyadenylation region can be derived from the natural gene, from a variety of other plant genes, or from T-DNA The 3' end sequence to be added can be derived from, example, the nopaline synthase or octopine synthase genes, or alternatively from another plant gene, or less preferably from any other eukaryotic gene An intron sequence can be added to the 5' untranslated region or the coding sequence of the partial coding sequence to increase the amount of the mature message that accumulates in the cytosol Inclusion of a spliceable intron in the transcription unit in both plant and animal expression constructs has been shown to increase gene expression at both the mRNA and protein levels up to 1000-fold Buchman et al (1988) Mol. Cell Biol. 8 4395-4405, Callis et al (1987) Genes Dev. 1 1183-1200 Such intron enhancement of gene expression is typically greatest when placed near the 5' end of the transcription unit Use of maize introns Adhl-S intron 1, 2, and 6, the Bronze-1 intron are known in the art See generally, The Maize Handbook, Chapter 116, Freeling and Walbot, eds , Springer, New York (1994) The vector comprising the sequences from a polynucleotide of the present invention could comprise a selectable marker gene for the selection of transformed cells or tissues Selectable marker genes include genes encoding antibiotic resistance, such as those encoding neomycin phosphotransferase II (NEO) and hygromycin phosphotransferase (HPT), as well as genes conferring resistance to herbicidal compounds, such as glufosinate ammonium, bromoxynil, imidazolinones, and 2,4- dichlorophenoxyacetate (2,4-D) See generally, Yarranton (1992) Curr. Opin. Biotech. 3 506-511, Christopherson et al. (1992) Proc. Natl. Acad Sci. USA 89 6314- 6318, Yao et al. (1992) Cell 71 63-72, Reznikoff (1992) Mol. Microbiol. 62419- 2422, Barkley etal. (1980) in The Operon, pp 177-220, Hu etal. (1987) Cell 48 555- 566, Brown etal. (1987) Cell 49 603-612, Figge et al. (1988) Cell 52 713-722, Deuschle et al. (1989) Proc. Natl. Aca Act. USA 86 5400-5404, Fuerst et al. (1989) Proc. Natl. Acad Sci. USA 862549-2553, Deuschle et al. (1990) Science 248 480- 483, Gossen (1993) Ph D Thesis, University of Heidelberg, Reines etal. (1993) Proc. Natl. Acad. Sci. USA 90 1917-1921, Labow et al. (\990)Mol. Cell. Biol. 10 3343-3356, Zambretti et al. (1992) Proc. Natl. Acad. Sci. USA 89 3952-3956, Bairn et al. (1991) roc. Natl. Acad. Sci. USA 88 5072-5076, Wyborski et al. (1991) Nucleic Acids Res. 194647-4653, Hillenand-Wissman (1989) Topics Mol. Struc. Biol. 10 143-162, Degenkolb et al. (1991) Antimicrob. Agents Chemother. 35 1591- 1595, Kleinschnidt et al. (1988) Biochemistry 27 1094-1104, Bonin (1993) Ph D Thesis, University of Heidelberg, Gossen et al. (1992) Proc. Natl. Acad Sci. USA 89 5547-5551, Oliva et al. (1992) Antimicrob. Agents Chemother. 36 913-919, Hlavka et al. (1985) Handbook of Experimental Pharmacology , Vol 78 ( Springer- Verlag, Berlin), Gill et al. (1988) Nature 334 721-724 Such disclosures are herein incorporated by reference The above list of selectable marker genes is not meant to be limiting Any selectable marker gene can be used in the present invention Typical vectors useful for expression of genes in higher plants are well known in the art and include vectors derived from the tumor-inducing (Ti) plasmid of Agrobacterium tumefaciens described by Rogers et al (1987) Meth. in Enzymol. 153 253-277 These vectors are plant integrating vectors in that on transformation, the vectors integrate a portion of vector DNA into the genome of the host plant Exemplary A tumefaciens vectors useful herein are plasmids pKYLXό and pKYLX7 of Schardl et al (1987) Gene 61 1-11 and Berger et al (1989) Proc. Natl. Acad. Sci. (USA) 86 8402-8406 Another useful vector herein is plasmid pBHOl 2 that is available from Clontech Laboratories, Inc (Palo Alto, CA) As discussed above, a polynucleotide of the present invention can be expressed in either sense or antisense orientation as desired It will be appreciated that control of gene expression in either sense or antisense orientation can have a direct impact on the observable plant characteristics Antisense technology can be conveniently used for gene expression in plants To accomplish this, a nucleic acid segment from the desired gene is cloned and operably linked to a promoter such that the antisense strand of R A will be transcribed The construct is then transformed into plants and the antisense strand of RNA is produced. In plant cells, it has been shown that antisense RNA inhibits gene expression by preventing the accumulation of mRNA which encodes the enzyme of interest, see, e.g., Sheehy et al (1988) Proc. Natl. Acad Sci. (USA) 85 8805-8809, and Hiatt et al, U S Patent No 4,801,340 In the methods of the invention, it is recognized that the entire coding sequence for the RPA construct may be utilized Alternatively, portions or fragments of the sequence may be used in DNA constructs Fragments and variants of the disclosed nucleotide sequences and proteins encoded thereby are encompassed by the present invention By "fragment" is intended a portion of the nucleotide sequence or a portion of the amino acid sequence and hence protein encoded thereby Fragments of a nucleotide sequence may encode protein fragments that retain the biological activity of the native protein and hence modulate DNA metabolism Alternatively, fragments of a nucleotide sequence that are useful as hybridization probes generally do not encode fragment proteins retaining biological activity Thus, fragments of a nucleotide sequence may range from at least about 20 nucleotides, about 50 nucleotides, about 100 nucleotides, and up to the full-length nucleotide sequence encoding the proteins of the invention A fragment of a RPA nucleotide sequence that encodes a biologically active portion of a RPA protein of the invention will encode at least 15, 25, 30, 50, 100, 150, 200, or 250 contiguous amino acids, or up to the total number of amino acids present in a full-length RPA protein of the invention (for example, 623, 617, 273, 273, 273, 318, 273, 273 amino acids for SEQ ID NOs 2, 4, 12, 14, 16, 18, 20, and 22 respectively Fragments of a RPA nucleotide sequence that are useful as hybridization probes for PCR primers generally need not encode a biologically active portion of a RPA protein. Thus, a fragment of a RPA nucleotide sequence may encode a biologically active portion of a RPA protein, or it may be a fragment that can be used as a hybridization probe or PCR primer using methods disclosed below A biologically active portion of a RPA protein can be prepared by isolating a portion of one of the RPA nucleotide sequences of the invention, expressing the encoded portion of the RPA protein (e g , by recombinant expression in vitro), and assessing the activity of the encoded portion of the RPA protein Nucleic acid molecules that are fragments of a RPA nucleotide sequence comprise at least 16, 20, 50, 75, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 800, 900, 1,000 nucleotides, or up to the number of nucleotides present in a full-length RPA nucleotide sequence disclosed herein (for example, 2497, 2202, 1124, 979, 1051, 1087, 1074, and 1231 nucleotides for SEQ ID NOs 1, 3, 11, 13, 15, 17, 19, and 21 respectively) By "variants" is intended substantially similar sequences For nucleotide sequences, conservative variants include those sequences that, because of the degeneracy of the genetic code, encode the amino acid sequence of one of the RPA polypeptides of the invention Such naturally occurring variants including naturally occurring allelic variants, can be identified with the use of well-known molecular biology techniques, as, for example, with polymerase chain reaction (PCR) and hybridization techniques as outlined below Variant nucleotide sequences also include synthetically derived nucleotide sequences, such as those generated, for example, by using site-directed mutagenesis but which still encode a RPA protein of the invention Generally, variants of a particular nucleotide sequence of the invention will have at least 40%, 50%), 60%>, 70%>, generally at least 75%>, 80%, 85%, preferably about 90% to 95%> or more, and more preferably about 98% or more sequence identity to that particular nucleotide sequence as determined by sequence alignment programs described elsewhere herein using default parameters By "variant" protein is intended a protein derived from the native protein by deletion (so-called truncation) or addition of one or more amino acids to the N- terminal and/or C-terminal end of the native protein, deletion or addition of one or more amino acids at one or more sites in the native protein, or substitution of one or more amino acids at one or more sites in the native protein Variant proteins encompassed by the present invention are biologically active, that is they continue to possess the desired biological activity of the native protein, that is, modulating DNA metabolism as described herein. Such variants may result from, for example, genetic polymorphism or from human manipulation Biologically active variants of a native RPA protein of the invention will have at least 40%, 50%, 60%, 70%, generally at least 75%, 80%, 85%, preferably about 90% to 95% or more, and more preferably about 98% or more sequence identity to the amino acid sequence for the native protein as determined by sequence alignment programs described elsewhere herein using default parameters A biologically active variant of a protein of the invention may differ from that protein by as few as 1-15 amino acid residues, as few as 1-10, such as 6-10, as few as 5, as few as 4, 3, 2, or even 1 amino acid residue The proteins of the invention may be altered in various ways including amino acid substitutions, deletions, truncations, and insertions Methods for such manipulations are generally known in the art For example, amino acid sequence variants of the RPA proteins can be prepared by mutations in the DNA Methods for mutagenesis and nucleotide sequence alterations are well known in the art See, for example, Kunkel (1985) Proc. Natl. Acad. Sci. USA 82 488-492, Kunkel et al. (1987) Methods in Enzymol. 154 367-382, US Patent No 4,873,192, Walker and Gaastra, eds (1983) Techniques in Molecular Biology (MacMillan Publishing Company, New York) and the references cited therein Guidance as to appropriate amino acid substitutions that do not affect biological activity of the protein of interest may be found in the model of Dayhoff et al (1978) Atlas of Protein Sequence and Structure (Natl Biomed Res Found , Washington, D C ), herein incorporated by reference Conservative substitutions, such as exchanging one amino acid with another having similar properties, may be preferred Thus, the genes and nucleotide sequences of the invention include both the naturally occurring sequences as well as mutant forms Likewise, the proteins of the invention encompass both naturally occurring proteins as well as variations and modified forms thereof. Such variants will continue to possess the desired activity in influencing DNA metabolism Obviously, the mutations that will be made in the DNA encoding the variant must not place the sequence out of reading frame and preferably will not create complementary regions that could produce secondary mRNA structure See, EP Patent Application Publication No 75,444 The deletions, insertions, and substitutions of the protein sequence encompassed herein are not expected to produce radical changes in the characteristics of the protein However, when it is difficult to predict the exact effect of the substitution, deletion, or insertion in advance of doing so, one skilled in the art will appreciate that the effect will be evaluated by routine screening assays That is, the activity can be evaluated by assessing DNA binding, recombination, repair and replication See, for example, Braun et al (1997) Biochemistry 36 8443-8454, Longhese et al (1994) Molecular and Cellular Biology 14 7884-7890, Stigger et al (1998) J. Biol. Chem. 273 9337-9343, Abremova et al (1997) Proc. Natl. Acad. Sci. USA 94 7186-7191, New et al (1998) Nature 391 407-410, Bochkareva et al (1998) J. Biol. Chem. 273(7) 3932- 6Mass et α/ (1998) Mol. Cell. Biol. 18(11) 6399-401, Lavrik et α/ (1998) Nucleic Acids Res 26(2) 602-7, Sibenaller et al (1998) 37(36) 12496-506, Matsunaga et al. (1996) J. Biol. Chem. 271 (19) 11047-50, and Sung (1997) Genes & Development 11 1111-21, herein incorporated by reference Variant nucleotide sequences and proteins also encompass nucleotide sequences and proteins derived from a mutagenic and recombinogenic procedure such as DΝA shuffling With such a procedure, one or more different RPA coding sequences can be manipulated to create a new RPA possessing the desired properties In this manner, libraries of recombinant polynucleotides are generated from a population of related sequence polynucleotides comprising sequence regions that have substantial sequence identity and can be homologously recombined in vitro or in vivo For example, using this approach, sequence motifs encoding a domain of interest may be shuffled between the RPA gene of the invention and other known RPA genes to obtain a new gene coding for a protein with an improved property of interest, such as an increased K m in the case of an enzyme Strategies for such DΝA shuffling are known in the art See, for example, Stemmer (1994) Proc. Natl. Acad. Sci. USA 91 10747-10751, Stemmer (1994) Nature 370 389-391, Crameri et al. (1997) Nature Biotech. 15 436-438, Moore et al. (1997) J. Mol. Biol. 272 336-347, Zhang et al. (1997) Proc. Natl. Acad. Sci. USA 94 4504-4509, Crameri et al. (1998) Nature 391 288-291, and U S Patent Nos 5,605,793 and 5,837,458 It is recognized that with these nucleotide sequences, antisense constructions, complementary to at least a portion of the messenger RNA (mRNA) for the RPA sequences can be constructed Antisense nucleotides are constructed to hybridize with the corresponding mRNA Modifications of the antisense sequences may be made as long as the sequences hybridize to and interfere with expression of the corresponding mRNA In this manner, antisense constructions having 70%, preferably 80%, more preferably 85% sequence similarity to the corresponding antisense sequences may be used Furthermore, portions of the antisense nucleotides may be used to disrupt the expression of the target gene Generally, sequences of at least 50 nucleotides, 100 nucleotides, 200 nucleotides, or greater may be used The nucleotide sequences of the present invention may also be used in the sense orientation to suppress the expression of endogenous genes in plants Methods for suppressing gene expression in plants using nucleotide sequences in the sense orientation are known in the art The methods generally involve transforming plants with a DNA construct comprising a promoter that drives expression in a plant operably linked to at least a portion of a nucleotide sequence that corresponds to the transcript of the endogenous gene Typically, such a nucleotide sequence has substantial sequence identity to the sequence of the transcript of the endogenous gene, preferably greater than about 65% sequence identity, more preferably greater than about 85% sequence identity, most preferably greater than about 95% sequence identity See, U S Patent Nos 5,283, 184 and 5,034,323, herein incorporated by reference Use of the polypeptides and proteins, and fragments and variants thereof, for producing antibodies are also encompassed by the invention The invention also encompasses using such antibodies to determine RPA protein levels, and to modulate one or more biological activities or interactions of RPA Methods for the production of antibodies are known in the art See, for example, Harlow and Lane, antibodies, A Laboratory Manual, Cold Spring Harbor Publications, New York (1988), and the reference is cited therein The RPA sequences of the invention may be optimized for enhanced expression in plants of interest See, for example, EPA0359472, WO91/16432, Perlak et al (1991) Proc. Natl. Acad. Sci. USA 88 3324-3328, and Murray et al (1989) Nucleic Acids Res. 17 477-498 In this manner, the genes can be synthesized utilizing plant-preferred condons See, for example, Murray et al (1989) Nucleic Acids Res. 17 477-498, the disclosure of which is incorporated herein by reference In this manner, synthetic genes can also be made based on the distribution of codons a particular host uses for a particular amino acid Thus, the nucleotide sequences can be optimized for expression in any plant It is recognized that all or any part of the gene sequence may be optimized or synthetic That is, synthetic or partially optimized sequences may also be used. Thus nucleotide sequences of the invention and the proteins encoded thereby include the native forms as well as variants thereof The variant proteins will be substantially homologous and functionally equivalent to the native proteins A variant of a native protein is "substantially homologous" to the native protein when at least about 80%, more preferably at least about 90%, and most preferably at least about 95% of its amino acid sequence is identical to the amino acid sequence of the native protein By "functionally equivalent" is intended that the sequence of the variant defines a chain that produces a protein having substantially the same biological effect as the native protein of interest Such functionally equivalent variants that comprise substantial sequence variations are also encompassed by the invention The nucleotide sequences of the invention can be used to isolate corresponding sequences from other organisms, particularly other plants, more particularly other monocots In this manner, methods such as PCR, hybridization, and the like can be used to identify such sequences based on their sequence homology to the sequence set forth herein Sequences isolated based on their sequence identity to the entire RPA sequences set forth herein or to fragments thereof are encompassed by the present invention In a PCR approach, oligonucleotide primers can be designed for use in PCR reactions to amplify corresponding DNA sequences from cDNA or genomic DNA extracted from any plant of interest Methods for designing PCR primers and PCR cloning are generally known in the art and are disclosed in Sambrook et al (1989) Molecular Cloning: A Laboratory Manual (2d ed , Cold Spring Harbor Laboratory Press, Plainview, New York) See also Innis et al , eds. (1990) PCR Protocols: A Guide to Methods and Applications (Academic Press, New York), Innis and Gelfand, eds (1995) PCR Strategies (Academic Press, New York), and Innis and Gelfand, eds ( 1999) PCR Methods Manual (Academic Press, New York) Known methods of PCR include, but are not limited to, methods using paired primers, nested primers, single specific primers, degenerate primers, gene-specific primers, vector-specific primers, partially-mismatched primers, and the like In hybridization techniques, all or part of a known nucleotide sequence is used as a probe that selectively hybridizes to other corresponding nucleotide sequences present in a population of cloned genomic DNA fragments or cDNA fragments (i e , genomic or cDNA libraries) from a chosen organism The hybridization probes may be genomic DNA fragments, cDNA fragments, RNA fragments, or other oligonucleotides, and may be labeled with a detectable group such as P, or any other detectable marker Thus, for example, probes for hybridization can be made by labeling synthetic oligonucleotides based on the RPA sequences of the invention Methods for preparation of probes for hybridization and for construction of cDNA and genomic libraries are generally known in the art and are disclosed in Sambrook et al (1989) Molecular Cloning: A Laboratory Manual (2d ed , Cold Spring Harbor Laboratory Press, Plainview, New York) For example, the entire RPA sequence disclosed herein, or one or more portions thereof, may be used as a probe capable of specifically hybridizing to corresponding RPA sequences and messenger RNAs To achieve specific hybridization under a variety of conditions, such probes include sequences that are unique among RPA sequences and are preferably at least about 10 nucleotides in length, and most preferably at least about 20 nucleotides in length Such probes may be used to amplify corresponding RPA sequences from a chosen plant by PCR This technique may be used to isolate additional coding sequences from a desired plant or as a diagnostic assay to determine the presence of coding sequences in a plant Hybridization techniques include hybridization screening of plated DNA libraries (either plaques or colonies, see, for example, Sambrook et al. (1989) Molecular Cloning: A Laboratory Manual (2d ed., Cold Spring Harbor Laboratory Press, Plainview, New York). Hybridization of such sequences may be carried out under stringent conditions. By "stringent conditions" or "stringent hybridization conditions" is intended conditions under which a probe will hybridize to its target sequence to a detectably greater degree than to other sequences (e.g., at least 2-fold over background). Stringent conditions are sequence-dependent and will be different in different circumstances By controlling the stringency of the hybridization and/or washing conditions, target sequences that are 100% complementary to the probe can be identified (homologous probing) Alternatively, stringency conditions can be adjusted to allow some mismatching in sequences so that lower degrees of similarity are detected (heterologous probing) Generally, a probe is less than about 1000 nucleotides in length, preferably less than 500 nucleotides in length Typically, stringent conditions will be those in which the salt concentration is less than about 1.5 M Na ion, typically about 0 01 to 1.0 M Na ion concentration (or other salts) at pH 7 0 to 8 3 and the temperature is at least about 30°C for short probes (e g., 10 to 50 nucleotides) and at least about 60°C for long probes (e.g., greater than 50 nucleotides) Stringent conditions may also be achieved with the addition of destabilizing agents such as formamide Exemplary low stringency conditions include hybridization with a buffer solution of 30 to 35% formamide, 1 M NaCl, 1% SDS (sodium dodecyl sulphate) at 37°C, and a wash in IX to 2X SSC (20X SSC = 3 0 M NaCl/0 3 M trisodium citrate) at 50 to 55°C Exemplary moderate stringency conditions include hybridization in 40 to 45% formamide, 1 0 M NaCl, 1% SDS at 37°C, and a wash in 0 5X to IX SSC at 55 to 60°C Exemplary high stringency conditions include hybridization in 50% formamide, 1 M NaCl, 1% SDS at 37°C, and a wash in 0. IX SSC at 60 to 65°C Specificity is typically the function of post-hybridization washes, the critical factors being the ionic strength and temperature of the final wash solution. For DNA-DNA hybrids, the T m can be approximated from the equation of Meinkoth and Wahl (1984) Anal. Biochem 138 267-284. T m = 81.5°C + 16 6 (log M) + 0 41 (%GC) - 0.61 (% form) - 500/L, where M is the molarity of monovalent cations, %GC is the percentage of guanosine and cytosine nucleotides in the DNA, % form is the percentage of formamide in the hybridization solution, and L is the length of the hybrid in base pairs The T m is the temperature (under defined ionic strength and pH) at which 50% of a complementary target sequence hybridizes to a perfectly matched probe T m is reduced by about 1°C for each 1% of mismatching, thus, T m , hybridization, and/or wash conditions can be adjusted to hybridize to sequences of the desired identity For example, if sequences with >90%> identity are sought, the T m can be decreased 10°C Generally, stringent conditions are selected to be about 5°C lower than the thermal melting point (T m ) for the specific sequence and its complement at a defined ionic strength and pH However, severely stringent conditions can utilize a hybridization and/or wash at 1, 2, 3, or 4°C lower than the thermal melting point (T m ), moderately stringent conditions can utilize a hybridization and/or wash at 6, 7, 8, 9, or 10°C lower than the thermal melting point (T m ), low stringency conditions can utilize a hybridization and/or wash at 1 1, 12, 13, 14, 15, or 20°C lower than the thermal melting point (T m ) Using the equation, hybridization and wash compositions, and desired T m , those of ordinary skill will understand that variations in the stringency of hybridization and/or wash solutions are inherently described If the desired degree of mismatching results in a T m of less than 45°C (aqueous solution) or 32°C (formamide solution), it is preferred to increase the SSC concentration so that a higher temperature can be used An extensive guide to the hybridization of nucleic acids is found in Tijssen (1993) Laboratory Techniques in Biochemistry and Molecular Biology — Hybridization with Nucleic Acid Probes, Part I, Chapter 2 (Elsevier, New York), and Ausubel et al, eds (1995) Current Protocols in Molecular Biology, Chapter 2 (Greene Publishing and Wiley-Interscience, New York) See Sambrook et al (1989) Molecular Cloning: A Laboratory Manual (2d ed , Cold Spring Harbor Laboratory Press, Plainview, New York) Thus, isolated sequences that have promoter activity or encode for a RPA protein and which hybridize under stringent conditions to the RPA sequences disclosed herein, or to fragments thereof, are encompassed by the present invention Such sequences will be at least 40% to 50% homologous, about 60% to 70% homologous, and even about 75%, 80%, 85%, 90%, 95% to 98% homologous or more with the disclosed sequences That is, the sequence identity of sequences may range, sharing at least 40% to 50%, about 60% to 70%, and even about 75%, 80%, 85%, 90%), 95%> to 98% or more sequence identity The following terms are used to describe the sequence relationships between two or more nucleic acids or polynucleotides (a) "reference sequence", (b) "comparison window", (c) "sequence identity", (d) "percentage of sequence identity", and (e) "substantial identity" (a) As used herein, "reference sequence" is a defined sequence used as a basis for sequence comparison A reference sequence may be a subset or the entirety of a specified sequence, for example, as a segment of a full-length cDNA or gene sequence, or the complete cDNA or gene sequence (b) As used herein, "comparison window" makes reference to a contiguous and specified segment of a polynucleotide sequence, wherein the polynucleotide sequence in the comparison window may comprise additions or deletions (i e , gaps) compared to the reference sequence (which does not comprise additions or deletions) for optimal alignment of the two sequences Generally, the comparison window is at least 20 contiguous nucleotides in length, and optionally can be 30, 40, 50, 100, or longer Those of skill in the art understand that to avoid a high similarity to a reference sequence due to inclusion of gaps in the polynucleotide sequence a gap penalty is typically introduced and is subtracted from the number of matches Methods of alignment of sequences for comparison are well known in the art Thus, the determination of percent identity between any two sequences can be accomplished using a mathematical algorithm Preferred, non-limiting examples of such mathematical algorithms are the algorithm of Myers and Miller (1988) CABIOS 4 1 1-17, the local homology algorithm of Smith et al (\9 \) Adv. Appl. Math. 2 482, the homology alignment algorithm of Needleman and Wunsch (1970) J. Mol. Biol. 48 443-453, the search-for-similarity-method of Pearson and Lipman (1988) Proc. Natl. Acad Sci. 85 2444-2448, the algorithm of Karlin and Altschul (1990) Proc. Natl. Acad. Sci. USA 872264, modified as in Karlin and Altschul (1993) Proc. Natl Acad. Sci. USA 90 5873-5877 Computer implementations of these mathematical algorithms can be utilized for comparison of sequences to determine sequence identity Such implementations include, but are not limited to CLUSTAL in the PC/Gene program (available from Intelligenetics, Mountain View, California), the ALIGN program (Version 2 0) and GAP, BESTFIT, BLAST, FASTA, and TFASTA in the Wisconsin Genetics Software Package, Version 8 (available from Genetics Computer Group (GCG), 575 Science Drive, Madison, Wisconsin, USA). Alignments using these programs can be performed using the default parameters. The CLUSTAL program is well described by Higgins et al (1988) Gene 73 237- 244 (1988), Higgins et al (1989) CABIOS 5 151-153, Corpet et al. (1988) Nucleic Aads Res 16 10881-90, Huang et al. (1992) CABIOS 8 155-65, and Pearson et al. (1994) Meth Mol Biol 24 307-331 The ALIGN program is based on the algorithm of Myers and Miller (1988) supra A PAM120 weight residue table, a gap length penalty of 12, and a gap penalty of 4 can be used with the ALIGN program when comparing amino acid sequences The BLAST programs of Altschul et al (1990) J Mol. Biol. 215 403 are based on the algorithm of Karlin and Altschul (1990) supra BLAST nucleotide searches can be performed with the BLASTN program, score = 100, wordlength = 12, to obtain nucleotide sequences homologous to a nucleotide sequence encoding a protein of the invention BLAST protein searches can be performed with the BLASTX program, score = 50, wordlength = 3, to obtain amino acid sequences homologous to a protein or polypeptide of the invention To obtain gapped alignments for comparison purposes, Gapped BLAST (in BLAST 2 0) can be utilized as described in Altschul et al (1997) Nucleic Acids Res 25 3389 Alternatively, PSI-BLAST (in BLAST 2 0) can be used to perform an iterated search that detects distant relationships between molecules See Altschul et al (1997) supra When utilizing BLAST, Gapped BLAST, PSI-BLAST, the default parameters of the respective programs (e g , BLASTN for nucleotide sequences, BLASTX for proteins) can be used See http //www ncbi nlm nih gov Alignment may also be performed manually by inspection Alignment may also be performed manually by inspection. For purposes of the present invention, comparison of nucleotide or protein sequences for determination of percent sequence identity to the RPA sequences disclosed herein is preferably made using the GCG PileUp program, version 10 00, with its default parameters or any equivalent program By "equivalent program" is intended any sequence comparison program that, for any two sequences in question, generates an alignment having identical nucleotide or amino acid residue matches and an identical percent sequence identity when compared to the corresponding alignment generated by the preferred program (c) As used herein, "sequence identity" or "identity" in the context of two nucleic acid or polypeptide sequences makes reference to the residues in the two sequences that are the same when aligned for maximum correspondence over a specified comparison window. When percentage of sequence identity is used in reference to proteins it is recognized that residue positions which are not identical often differ by conservative amino acid substitutions, where amino acid residues are substituted for other amino acid residues with similar chemical properties (e.g., charge or hydrophobicity) and therefore do not change the functional properties of the molecule. When sequences differ in conservative substitutions, the percent sequence identity may be adjusted upwards to correct for the conservative nature of the substitution. Sequences that differ by such conservative substitutions are said to have "sequence similarity" or "similarity". Means for making this adjustment are well known to those of skill in the art. Typically this involves scoring a conservative substitution as a partial rather than a full mismatch, thereby increasing the percentage sequence identity. Thus, for example, where an identical amino acid is given a score of 1 and a non-conservative substitution is given a score of zero, a conservative substitution is given a score between zero and 1. The scoring of conservative substitutions is calculated, e.g., as implemented in the program PC/GENE (Intelligenetics, Mountain View, California). (d) As used herein, "percentage of sequence identity" means the value determined by comparing two optimally aligned sequences over a comparison window, wherein the portion of the polynucleotide sequence in the comparison window may comprise additions or deletions (i.e., gaps) as compared to the reference sequence (which does not comprise additions or deletions) for optimal alignment of the two sequences. The percentage is calculated by determining the number of positions at which the identical nucleic acid base or amino acid residue occurs in both sequences to yield the number of matched positions, dividing the number of matched positions by the total number of positions in the window of comparison, and multiplying the result by 100 to yield the percentage of sequence identity. (e)(i) The term "substantial identity" of polynucleotide sequences means that a polynucleotide comprises a sequence that has at least 70% sequence identity, preferably at least 80%, more preferably at least 90%, and most preferably at least 95%>, compared to a reference sequence using one of the alignment programs described using standard parameters One of skill in the art will recognize that these values can be appropriately adjusted to determine corresponding identity of proteins encoded by two nucleotide sequences by taking into account codon degeneracy, amino acid similarity, reading frame positioning, and the like. Substantial identity of amino acid sequences for these purposes normally means sequence identity of at least 60%>, more preferably at least 70%, 80%, 90%, and most preferably at least 95%> Another indication that nucleotide sequences are substantially identical is if two molecules hybridize to each other under stringent conditions Generally, stringent conditions are selected to be about 5°C lower than the thermal melting point (T m ) for the specific sequence at a defined ionic strength and pH However, stringent conditions encompass temperatures in the range of about 1°C to about 20°C, depending upon the desired degree of stringency as otherwise qualified herein Nucleic acids that do not hybridize to each other under stringent conditions are still substantially identical if the polypeptides they encode are substantially identical This may occur, e g , when a copy of a nucleic acid is created using the maximum codon degeneracy permitted by the genetic code One indication that two nucleic acid sequences are substantially identical is when the polypeptide encoded by the first nucleic acid is immunologically cross reactive with the polypeptide encoded by the second nucleic acid (e)(ii) The term "substantial identity" in the context of a peptide indicates that a peptide comprises a sequence with at least 70% sequence identity to a reference sequence, preferably 80%, more preferably 85%, most preferably at least 90%) or 95%o sequence identity to the reference sequence over a specified comparison window Preferably, optimal alignment is conducted using the homology alignment algorithm of Needleman et al (1970) J. Mol. Biol. 48 443 An indication that two peptide sequences are substantially identical is that one peptide is immunologically reactive with antibodies raised against the second peptide Thus, a peptide is substantially identical to a second peptide, for example, where the two peptides differ only by a conservative substitution Peptides that are "substantially similar" share sequences as noted above except that residue positions that are not identical may differ by conservative amino acid changes Using the nucleic acids of the present invention, one may express a protein of the present invention in a recombinantly engineered cell such as bacteria, yeast, insect, mammalian, or preferably plant cells The cells produce the protein in a non-natural condition (e g , in quantity, composition, location, and/or time), because they have been genetically altered through human intervention to do so It is expected that those of skill in the art are knowledgeable in the numerous expression systems available for expression of a nucleic acid encoding a protein of the present invention No attempt to describe in detail the various methods known for the expression of proteins in prokaryotes or eukaryotes will be made In brief summary, the expression of isolated nucleic acids encoding a protein of the present invention will typically be achieved by operably linking, for example, the DNA or cDNA to a promoter (which is either constitutive or inducible), followed by incorporation into an expression vector The vectors can be suitable for replication and integration in either prokaryotes or eukaryotes Typical expression vectors contain transcription and translation terminators, initiation sequences, and promoters useful for regulation of the expression of the DNA encoding a protein of the present invention To obtain high level expression of a cloned gene, it is desirable to construct expression vectors which contain, at the minimum, a strong promoter to direct transcription, a ribosome binding site for translational initiation, and a transcription/translation terminator One of skill would recognize that modifications can be made to a protein of the present invention without diminishing its biological activity Some modifications may be made to facilitate the cloning, expression, or incorporation of the targeting molecule into a fusion protein Such modifications are well known to those of skill in the art and include, for example, a methionine added at the amino terminus to provide an initiation site, or additional amino acids (e g , poly His) placed on either terminus to create conveniently located restriction sites or termination codons or purification sequences Prokaryotic cells may be used as hosts for expression Prokaryotes most frequently are represented by various strains of E coli, however, other microbial strains may also be used Commonly used prokaryotic control sequences which are defined herein to include promoters for transcription initiation, optionally with an operator, along with ribosome binding site sequences, include such commonly used promoters as the beta lactamase (penicillinase) and lactose (lac) promoter systems (Chang et al (1977) Nature 198 1056), the tryptophan (trp) promoter system (Goeddel et al (1980) Nucleic Acids Res. 8 4057) and the lambda-derived P L promoter and N-gene ribosome binding site (Shimatake et al (1981) Nature 292 128) The inclusion of selection markers in DNA vectors transfected in E. coli is also useful Examples of such markers include genes specifying resistance to ampicillin, tetracycline, or chloramphenicol. The vector is selected to allow introduction into the appropriate host cell Bacterial vectors are typically of plasmid or phage origin Appropriate bacterial cells are infected with phage vector particles or transfected with naked phage vector DNA If a plasmid vector is used, the bacterial cells are transfected with the plasmid vector DNA Expression systems for expressing a protein of the present invention are available using Bacillus sp and Salmonella (Palva et al (1983) Gene 22 229-235, Mosbach et al (1983) Nature 302 543-545) A variety of eukaryotic expression systems such as yeast, insect cell lines, plant and mammalian cells, are known to those of skill in the art The sequences of the present invention can be expressed in these eukaryotic systems In some embodiments, transformed/transfected plant cells are employed as expression systems for production of the proteins of the instant invention Synthesis of heterologous proteins in yeast is well known Sherman, F et al (1982) Methods in Yeast Genetics, Cold Spring Harbor Laboratory is a well recognized work describing the various methods available to produce the protein in yeast Two widely utilized yeast for production of eukaryotic proteins are Saccharomyces cerevisia and Pichia pastoris Vectors, strains, and protocols for expression in Saccharomyces and Pichia are known in the art and available from commercial suppliers (e g , Invitrogen) Suitable vectors usually have expression control sequences, such as promoters, including 3-phosphoglycerate kinase or alcohol oxidase, and an origin of replication, termination sequences and the like as desired A protein of the present invention, once expressed, can be isolated from yeast by lysing the cells and applying standard protein isolation techniques to the lysates The monitoring of the purification process can be accomplished by using Western blot techniques or radioimmunoassay of other standard immunoassay techniques The sequences encoding proteins of the present invention can also be ligated to various expression vectors for use in transfecting cell cultures of, for instance, mammalian, insect, or plant origin Illustrative of cell cultures useful for the production of the peptides are mammalian cells Mammalian cell systems often will be in the form of monolayers of cells although mammalian cell suspensions may also be used A number of suitable host cell lines capable of expressing intact proteins have been developed in the art, and include the HEK293, BHK21, and CHO cell lines Expression vectors for these cells can include expression control sequences, such as an origin of replication, a promoter (e g , the CMV promoter, a HSV tk promoter or pgk (phosphoglycerate kinase promoter)), an enhancer (Queen et al (1986) Immunol. Rev. 89 49), and necessary processing information sites, such as ribosome binding sites, RNA splice sites, polyadenylation sites (e g , an SV40 large T Ag poly A addition site), and transcriptional terminator sequences Other animal cells useful for production of proteins of the present invention are available, for instance, from the American Type Culture Collection Catalogue of Cell Lines and Hybridomas (7th edition, 1992) Appropriate vectors for expressing proteins of the present invention in insect cells are usually derived from the SF9 baculovirus Suitable insect cell lines include mosquito larvae, silkworm, armyworm, moth and Drosophila cell lines such as a Schneider cell line (See Schneider et al (1987) J. Embryol Exp. Morphol 27 353-365) As with yeast, when higher animal or plant host cells are employed, polyadenylation or transcription terminator sequences are typically incorporated into the vector An example of a terminator sequence is the polyadenylation sequence from the bovine growth hormone gene Sequences for accurate splicing of the transcript may also be included An example of a splicing sequence is the VPl intron from SV40 (Sprague et al (1983) J. Virol. 45 773-781) Additionally, gene sequences to control replication in the host cell may be incorporated into the vector such as those found in bovine papilloma virus-type vectors Saveria- Campo, M , Bovine Papilloma Virus DNA a Eukaryotic Cloning Vector in DNA Cloning Vol. II a Practical Approach, D M Glover, ed , IRL Press, Arlington, Virginia pp 213-238 (1985) The sequences of the invention can be introduced into any plant of interest, and used for transformation of any plant species The sequences to be introduced may be used in expression cassettes for expression in the particular plant of interest Plants of interest include, but are not limited to corn (Zea mays), Brassica sp (e g , B. napus, B. rapa, B. juncea), particularly those Brassica species useful as sources of seed oil, alfalfa (Medicago sativa), rice (Oryza sativa), rye (Secale cereale), sorghum (Sorghum bicolor, Sorghum vulgare), millet (e g , pearl millet (Pennisetum glaucum), proso millet (Panicum mihaceum), foxtail millet (Setaria italica), finger millet (Eleusine coracana)), sunflower (Hehanthus annuus), safflower (Carthamus tinctorius), wheat (Triticum aestivum), soybean (Glycine max), tobacco (Nicotiana tabacum), potato (Solanum tuberosum), peanuts (Arachis hypogaed), cotton (Gossypium barbadense, Gossypium hirsutum), sweet potato (Ipomoea batatus), cassava (Manihot esculenta), coffee (Cofea spp ), coconut (Cocos nucifera), pineapple (Ananas comosus), citrus trees (Citrus spp ), cocoa (Theobroma cacao), tea (Camellia sinensis), banana (Musa spp ), avocado (Persea americana), fig (Ficus casica), guava (Psidium guajava), mango (Mangifera indicd), olive (Olea europaea), papaya (Car ica papaya), cashew (Anacardium occidentale), macadamia (Macadamia integrifolia), almond (Prunus amygaalus), sugar beets (Beta vulgaris), sugarcane (Saccharum spp ), oats, barley, vegetables, ornamentals, and conifers Vegetables include tomatoes (Lycopersicon esculentum), lettuce (e g , Lactuca sativa), green beans (Phaseolus vulgaris), lima beans (Phaseolus hmensis), peas (Lathyrus spp ), and members of the genus Cucumis such as cucumber (C. sativus), cantaloupe (C. cantalupensis), and musk melon (C. melo) Ornamentals include azalea (Rhododendron spp ), hydrangea (Macrophylla hydrangea), hibiscus (Hibiscus rosasanensis), roses (Rosa spp ), tulips (Tuhpa spp ), daffodils (Narcissus spp ), petunias (Petunia hybridd), carnation (Dianthus caryophyllus), poinsettia (Euphorbia pulcherrima), and chrysanthemum Conifers that may be employed in practicing the present invention include, for example, pines such as loblolly pine (Pinus taeda), slash pine (Pinus elhotii), ponderosa pine (Pinus ponderosa), lodgepole pine (Pinus contorta), and Monterey pine (Pinus radiata), Douglas-fir (Pseudotsuga menziesn), Western hemlock (Tsuga canadensis), Sitka spruce (Picea glauca), redwood (Sequoia sempervirens), true firs such as silver fir (Abies amabilis) and balsam fir (Abies balsamea), and cedars such as Western red cedar (Thuja plicata) and Alaska yellow-cedar (Chamaecypans nootkatensis) Preferably, plants of the present invention are crop plants (for example, corn, alfalfa, sunflower, Brassica, soybean, cotton, safflower, peanut, sorghum, wheat, millet, tobacco, etc.), more preferably corn and soybean plants, yet more preferably corn plants Plants of particular interest include grain plants that provide seeds of interest, oil-seed plants, and leguminous plants Seeds of interest include grain seeds, such as corn, wheat, barley, rice, sorghum, rye, etc Oil-seed plants include cotton, soybean, safflower, sunflower, Brassica, maize, alfalfa, palm, coconut, etc Leguminous plants include beans and peas Beans include guar, locust bean, fenugreek, soybean, garden beans, cowpea, mungbean, lima bean, fava bean, lentils, chickpea, etc The RPA coding and antisense sequences of the invention are provided in expression cassettes for expression in the plant of interest The cassette will include 5' and 3' regulatory sequences operably linked to a RPA sequence of the invention The cassette may additionally contain at least one additional gene to be cotransformed into the organism Alternatively, the additional gene(s) can be provided on another expression cassette By "operably linked" is intended a functional linkage between a promoter and a second sequence, wherein the promoter sequence initiates and mediates transcription of the DNA sequence corresponding to the second sequence Generally, operably linked means that the nucleic acid sequences being linked are contiguous and, where necessary to join two protein coding regions, contiguous and in the same reading frame Such an expression cassette is provided with a plurality of restriction sites for insertion of the RPA sequence to be under the transcriptional regulation of the regulatory regions The expression cassette may additionally contain selectable marker genes The expression cassette will include in the 5'-3' direction of transcription, a transcriptional and translational initiation region, a RPA DNA sequence of the invention, and a transcriptional and translational termination region functional in plants The transcriptional initiation region, the promoter, may be native or analogous or foreign or heterologous to the plant host Additionally, the promoter may be the natural sequence or alternatively a synthetic sequence By "foreign" is intended that the transcriptional initiation region is not found in the native plant into which the transcriptional initiation region is introduced As used herein, a chimeric gene comprises a coding sequence operably linked to a transcription initiation region that is heterologous to the coding sequence While it may be preferable to express the sequences using heterologous promoters, the native promoter sequences may be used Such constructs would change expression levels of RPA in the plant or plant cell Thus, the phenotype of the plant or plant cell is altered The termination region may be native with the transcriptional initiation region, may be native with the operably linked DNA sequence of interest, or may be derived from another source Convenient termination regions are available from the Ti-plasmid of A. tumefaciens, such as the octopine synthase and nopaline synthase termination regions See also Guerineau et al. (1991) Mol. Gen. Genet. 262 141-144, Proudfoot (1991) Cell 64 671-674, Sanfacon et al. (1991) Genes Dev. 5 141-149, Mogen et al. (1990) Plant Cell 2 1261-1272, Munroe et al. (1990) Gene 91 151-158, Ballas et al. (1989) Nucleic Acids Res. 17 7891-7903, and Joshi et al. (1987) Nucleic Acid Res. 15 9621-9639 Where appropriate, the gene(s) may be optimized for increased expression in the transformed plant That is, the genes can be synthesized using plant- preferred codons for improved expression See, for example, Campbell and Gowri (1990) Plant Physiol. 92 1-11 for a discussion of host-preferred codon usage Methods are available in the art for synthesizing plant-preferred genes See, for example, U S Patent Nos 5,380,831, and 5,436,391, and Murray et al (1989) Nucleic Acids Res. 77477-498, herein incorporated by reference Additional sequence modifications are known to enhance gene expression in a cellular host These include elimination of sequences encoding spurious polyadenylation signals, exon-intron splice site signals, transposon-like repeats, and other such well-characterized sequences that may be deleterious to gene expression The G-C content of the sequence may be adjusted to levels average for a given cellular host, as calculated by reference to known genes expressed in the host cell When possible, the sequence is modified to avoid predicted hairpin secondary mRNA structures The expression cassettes may additionally contain 5' leader sequences in the expression cassette construct Such leader sequences can act to enhance translation Translation leaders are known in the art and include picornavirus leaders, for example, EMCV leader (Encephalomyocarditis 5' noncoding region) (Elroy-Stein et al (1989) PNAS USA 86 6126-6130), potyvirus leaders, for example, TEV leader (Tobacco Etch Virus) (Allison et al. (1986), MDMV leader (Maize Dwarf Mosaic Virus), Virology 154 9-20), and human immunoglobulin heavy-chain binding protein (BiP), (Macejak et al (1991) Nature 353 90-94), untranslated leader from the coat protein mRNA of alfalfa mosaic virus (AMV RNA 4) (Jobling et al (1987) Nature 325 622-625), tobacco mosaic virus leader (TMV) (Gallie et al. ( 1989) in Molecular Biology of RNA, ed Cech (Liss, New York), pp 237-256), and maize chlorotic mottle virus leader (MCMV) (Lommel et al (1991) Virology 81 382-385) See also, Della-Cioppa et al. (1987) Plant Physiol. 84 965-968 Other methods known to enhance translation can also be utilized, for example, introns, and the like. In preparing the expression cassette, the various DNA fragments may be manipulated, so as to provide for the DNA sequences in the proper orientation and, as appropriate, in the proper reading frame Toward this end, adapters or linkers may be employed to join the DNA fragments or other manipulations may be involved to provide for convenient restriction sites, removal of superfluous DNA, removal of restriction sites, or the like For this purpose, in vitro mutagenesis, primer repair, restriction, annealing, resubstitutions, e g , transitions and transversions, may be involved The sequences of the present invention can be used to transform or transfect any plant In this manner, genetically modified plants, plant cells, plant tissue, seed, and the like can be obtained Transformation protocols as well as protocols for introducing nucleotide sequences into plants may vary depending on the type of plant or plant cell, i e , monocot or dicot, targeted for transformation Suitable methods of introducing nucleotide sequences into plant cells and subsequent insertion into the plant genome include microinjection (Crossway et al (1986) Biotechmques 4 320-334), electroporation (Riggs et al (1986) Proc. Natl. Acad. Sci. USA 83 5602-5606, Agrobacterium-mediaXed transformation (Townsend et α/ , U S Pat No 5,563,055), direct gene transfer (Paszkowski et αl (1984) EMBO J. 3 2717-2722), and ballistic particle acceleration (see, for example, Sanford et αl , U S Patent No 4,945,050, Tomes et αl , U S Patent No 5,879,918, Tomes et αl , U S Patent No 5,886,244, Bidney et αl , U S Patent No 5,932,782, Tomes et αl (1995) "Direct DNA Transfer into Intact Plant Cells via Microprojectile Bombardment," in Plant Cell, Tissue, and Organ Culture: Fundamental Methods, ed Gamborg and Phillips (Springer- Verlag, Berlin), and McCabe et α/ (1988) Biotechnology 6 923-926) Also see Weissinger et al (1988) Ann. Rev. Genet. 22 421-477, Sanford et al (1987) Particulate Science and Technology 5 27-37 (onion), Christou et al (1988) Plant Physiol 87 671-674 (soybean), McCabe et al (1988) Bio/Technology 6 923-926 (soybean), Finer and McMullen (1991) In Vitro Cell Dev. Biol. 27P 175-182 (soybean), Singh et al (1998) Theor. Appl. Genet. 96 3 X9-324 (soybean), Datta et α/ (1990) Biotechnology 8 736-740 (rice), Klein et al (1988) Proc. Natl. Acad. Sci. USA 85 4305-4309 (maize), Klein et al (1988) Biotechnology 6 559-563 (maize), Tomes, U S Patent No 5,240,855, Buising et al , U S Patent Nos 5,322,783 and 5,324,646, Tomes et al. (1995) "Direct DNA Transfer into Intact Plant Cells via Microprojectile Bombardment," in Plant Cell, Tissue, and Organ Culture: Fundamental Methods, ed Gamborg (Springer- Verlag, Berlin) (maize), Klein et al (1988) Plant Physiol. 91 440-444 (maize), Fromm et al (1990) Biotechnology 8 833-839 (maize), Hooykaas-Van Slogteren et al (1984) Nature (London) 311 763-764, Bowen et al, U S Patent No 5,736,369 (cereals), Bytebier et al (1987) Proc. Natl. Acad. Sci. USA 84 5345-5349 (Liliaceae), De Wet et al (1985) in The Experimental Manipulation o Ovule Tissues, ed Chapman et al (Longman, New York), pp 197-209 (pollen), Kaeppler et al (1990) Plant Cell Reports 9 415- 418 and Kaeppler et al (1992) Theor. Appl. Genet. 84 560-566 (whisker-mediated transformation), D'Halluin et al (1992) Plant Cell 4 1495-1505 (electroporation), Li et al (1993) Plant Cell Reports 12 250-255 and Christou and Ford (1995) Annals of Botany 75 407-413 (rice), Osjoda et al (1996) Nature Biotechnology 14 745-750 (maize via. Agrobacterium tumefaciens), all of which are herein incorporated by reference The cells that have been transformed may be grown into plants in accordance with conventional ways. See, for example, McCormick et al. (1986) Plant Cell Reports 5:81-84. These plants may then be grown, and either pollinated with the same transformed strain or different strains, and the resulting hybrid having constitutive expression of the desired phenotypic characteristic identified. Two or more generations may be grown to ensure that expression of the desired phenotypic characteristic is stably maintained and inherited and then seeds harvested to ensure expression of the desired phenotypic characteristic has been achieved. Transgenic plants expressing the selectable marker can be screened for transmission of the nucleic acid of the present invention by, for example, standard immunoblot and DNA detection techniques. Transgenic lines are also typically evaluated on levels of expression of the heterologous nucleic acid. Expression at the RNA level can be determined initially to identify and quantitate expression- positive plants. Standard techniques for RNA analysis can be employed and include PCR amplification assays using oligonucleotide primers designed to amplify only the heterologous RNA templates and solution hybridization assays using heterologous nucleic acid-specific probes. The RNA-positive plants can then be analyzed for protein expression by Western immunoblot analysis using the specifically reactive antibodies of the present invention. In addition, in situ hybridization and immunocytochemistry according to standard protocols can be done using heterologous nucleic acid specific polynucleotide probes and antibodies, respectively, to localize sites of expression within transgenic tissue. Generally, a number of transgenic lines are usually screened for the incorporated nucleic acid to identify and select plants with the most appropriate expression profiles. A preferred embodiment is a transgenic plant that is homozygous for the added heterologous nucleic acid; i.e., a transgenic plant that contains two added nucleic acid sequences, one gene at the same locus on each chromosome of a chromosome pair. A homozygous transgenic plant can be obtained by sexually mating (selfing) a heterozygous transgenic plant that contains a single added heterologous nucleic acid, germinating some of the seed produced and analyzing the resulting plants produced for altered RPA expression relative to a control plant (i.e , native, non-transgenic) Backcrossing to a parental plant and out-crossing with a non-transgenic plant are also contemplated The present invention further provides a method for modulating (i.e., increasing or decreasing) RPA levels in a plant or part thereof Modulation can be effected by increasing or decreasing the total amount of RPA (i e , its content) and/or the ratio of various RPA subunit proteins (i e , its composition) in the plant The method comprises transforming a plant cell with a recombinant expression cassette comprising a polynucleotide of the present invention as described above to obtain a transformed plant cell, growing the transformed plant cell under plant forming conditions, and inducing expression of a polynucleotide of the present invention in the plant for a time sufficient to modulate RPA content and/or composition in the plant or plant part In some embodiments, RPA in a plant may be modulated by altering, in vivo or in vitro, the promoter of a non-isolated RPA gene to up- or down-regulate gene expression In some embodiments, the coding regions of native RPA genes an be altered via substitution, addition, insertion, or deletion to decrease activity of the encoded enzyme See, e g , Kmiec, U S Patent 5,565,350, Zarling et al , PCT/US93/03868 And in some embodiments, an isolated nucleic acid (e g , a vector) comprising a promoter sequence is transfected into a plant cell Subsequently, a plant cell comprising the promoter operably linked to a polynucleotide of the present invention is selected by means known to those of skill in the art such as, but not limited to, Southern blot, DNA sequencing, or PCR analysis using primers specific to the promoter and to the gene and detecting amplicons produced therefrom A plant or plant part altered or modified by the foregoing embodiments is grown under plant forming conditions for a time sufficient to modulate RPA content and/or composition in the plant Plant forming conditions are well known in the art and discussed briefly, supra In general, content or composition is increased or decreased by at least 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% relative to a native control plant, plant part, or cell lacking the aforementioned recombinant expression cassette Modulation in the present invention may occur during and/or subsequent to growth of the plant to the desired stage of development Modulating nucleic acid expression temporally and/or in particular tissues can be controlled by employing the appropriate promoter operably linked to a polynucleotide of the present invention in, for example, sense or antisense orientation as discussed in greater detail, supra Induction of expression of a polynucleotide of the present invention can also be controlled by exogenous administration of an effective amount of inducing compound Inducible promoters and inducing compounds that activate expression from these promoters are well known in the art In preferred embodiments, RPA is modulated in monocots, particularly maize The ability of RPA to interact with multiple proteins or protein complexes allows it to participate and regulate these multiple pathways of DNA metabolism For example, it has been shown in mammalian systems that are RPA interacts with DNA polymerase alpha (Barun et al (1997) Biochemistry 36 8443-8454), p53 (Dutta et al (1993) Nature 365 79-82), RAD 62 (Park et al (1996) J. Biol. Chem. 271 18996-19000) Participation of the middle subunit of RPA in protein-protein interactions has also been shown Examples of such interactions include, but are not limited to interactions with XPA protein and RAD 52 (He et al (1995) Nature 374 566-69, Matsuda et al (1995) J. Biol. Chem. 270 4152-57, Li et al (1995) Mol. Cell. Biol. 15 5396-402, Park et al (1996) J. Biol. Chem. 271 18996-19000), and PCNA (Shivji et al (1995) Biochemistry 34 501 1-5017) Similarly, yeast RPA has been shown to be involved in multiple functions in DNA metabolism (Umezu et al (1998) Genetics 148 989-1005) Therefore, the proteins of the invention may be useful as a ligand to purify and clone other proteins involved in DNA recombination, repair, and replication Particularly, the maize proteins may be useful to purify other maize proteins involved in DNA metabolism For example, the RPA proteins of the invention may be insolubilized on a solid matrix (e g agrose or nylon beads) for affinity purification, or the RPA cDNA may be used as a bait in a yeast to-hybrid system In this manner, other proteins may be used identified and isolated The following examples are offered by way of illustration and not by way of limitation EXPERIMENTAL Example 1 cDNA Cloning Total RNA was isolated from corn tissues with TRIzol Reagent (Life Technology, Inc Gaithersburg, MD) using a modification of the guanidine isothiocyanate/acid-phenol procedure described by Chomozynski and Sacchi (Chomczynski et al (1987) Anal. Biochem. 162 156) In brief, plant tissue samples were pulverized in liquid nitrogen before the addition of the TRIzol Reagent, and then were further homogenized with a mortar and pestle Addition of chloroform by centrifugation was conducted for separation of an aqueous phase and an organic phase The total RNA was recovered by precipitation with isopropyl alcohol from the aqueous phase The selection of poly(A)+RNA from total RNA was performed using PolyATract system (Promega Corporation, Madison, WI) In brief, biotinylated oligo (dT) primers were used to hybridize to the 3' poly(A) tails on mRNA The hybrids were captured using streptavidin coupled to paramagnetic particles and a magnetic separation stand The mRNA was washed at high stringent condition and eluted by Rnase-free deionized water. Synthesis of the cDNA was performed and unidirectional cDNA libraries were constructed using the Superscript Plasmid System (Life Technology, Inc , Gaithersburg, MD) First strand of CDNA was synthesized by priming an oligo(dT) primer containing a Not I site The reaction was catalyzed by Superscript Reverse Transcriptase II at 45°C The second strand of cDNA was labeled with α- 32 P-dCTP and portions of the molecules smaller than 500 base pairs and unhgated adapters were removed by Sephacryl-S400 chromatography The selected cDNA molecules were ligated into pSPORTl reference vector between the Not I and Sal I sites Individual colonies were picked and DNA was prepared either by PCR with Ml 3 forward primers and Ml 3 reverse primers, or by plasmid miniprep isolation All the cDNA clones were sequenced using Ml 3 reverse primers Two maize homologues for RPA large subunit (ZmRPALSH) have been isolated The genes map to two different chromosomes as shown below in Table 1 The ammo acid and nucleotide sequences for the two homologues are set forth in SEQ ID NOs 1-4 Table 1 Maize RPA Large Subunit Genes Map to Two Different Chromosomes Ten ESTs, which form two different contigs for maize RPA large subunit, were used as probes for mapping experiments Each contig represents one maize homologue for RPALS Seven maize homologues for RPA middle subunit (ZmRPAMSH) have been isolated The genes map to chromosomes 5 as shown below in Table 2 The nucleotide and amino acid sequences of the seven homologues are set forth in SEQ ID NOs 11-22 Table 2 Maize Homologues of Eukaryotic Replication Protein A Middle Subunit TBD = To be determined Example 2 Transformation and Regeneration of Trnsgenic Plants Immature maize embryos from greenhouse donor plants are bombarded with a plasmid containing the RPA antisense sequence of the invention operably linked to a pathogen-inducible promoter (Figure 2) plus a plasmid containing the selectable marker gene PAT (Wohlleben et al (1988) Gene 70 25-37) that confers resistance to the herbicide Bialaphos Transformation is performed as follows All media recipes are in the Appendix Preparation of Target Tissue The ears are surface sterilized in 30%> Chlorox bleach plus 0 5%> Micro detergent for 20 minutes, and rinsed two times with sterile water The immature embryos are excised and placed embryo axis side down (scutellum side up), 25 embryos per plate, on 560Y medium for 4 hours and then aligned within the 2 5- cm target zone in preparation for bombardment Preparation of DNA A plasmid vector comprising the RPA sequence of the invention operably linked to a ubiquitin promoter is made. This plasmid DNA plus plasmid DNA containing a PAT selectable marker is precipitated onto 1.1 μm (average diameter) tungsten pellets using a CaCl 2 precipitation procedure as follows: 100 μl prepared tungsten particles in water 10 μl (1 μg) DNA in TrisEDTA buffer (1 μg total) 100 μl 2.5 M CaCl 2 10 μl 0.1 M spermidine Each reagent is added sequentially to the tungsten particle suspension, while maintained on the multitube vortexer. The final mixture is sonicated briefly and allowed to incubate under constant vortexing for 10 minutes. After the precipitation period, the tubes are centrifuged briefly, liquid removed, washed with 500 ml 100% ethanol, and centrifuged for 30 seconds. Again the liquid is removed, and 105 μl 100%> ethanol is added to the final tungsten particle pellet. For particle gun bombardment, the tungsten/DNA particles are briefly sonicated and 10 μl spotted onto the center of each macrocarrier and allowed to dry about 2 minutes before bombardment. Particle Gun Treatment The sample plates are bombarded at level #4 in particle gun #HE34-1 or #HE34-2. All samples receive a single shot at 650 PSI, with a total often aliquots taken from each tube of prepared particles/DNA. Subsequent Treatment Following bombardment, the embryos are kept on 560Y medium for 2 days, then transferred to 560R selection medium containing 3 mg/liter Bialaphos, and subcultured every 2 weeks. After approximately 10 weeks of selection, selection-resistant callus clones are transferred to 288J medium to initiate plant regeneration. Following somatic embryo maturation (2-4 weeks), well-developed somatic embryos are transferred to medium for germination and transferred to the lighted culture room. Approximately 7-10 days later, developing plantlets are transferred to 272V hormone-free medium in tubes for 7-10 days until plantlets are well established. Plants are then transferred to inserts in flats (equivalent to 2.5" pot) containing potting soil and grown for 1 week in a growth chamber, subsequently grown an additional 1-2 weeks in the greenhouse, then transferred to classic 600 pots (1.6 gallon) and grown to maturity. Plants are monitored and scored for expression of the RPA gene of interest. APPENDIX 272 V Directions @ = Add after bringing up to volume Dissolve ingredients in polished D-I H 2 O in sequence Adjust to pH 5 6 Bring up to volume with polished D-I H 2 O after adjusting pH Sterilize and cool to 60°C ## = Dissolve 0 100 g of Nicotinic Acid, 0 020 g of Thiamine HCL, 0 100 g of Pyridoxine HCL, and 0 400 g of Glycine in 875 00 ml of polished D-I H 2 O in sequence Bring up to volume with polished D-I H O Make in 400 ml portions Thiamine HCL & Pyridoxine HCL are in Dark Desiccator Store for one month, unless contamination or precipitation occurs, then make fresh stock Total Volume (L) = 1 00 288 J Directions @ = Add after bringing up to volume Dissolve ingredients in polished D-I H 2 O in sequence Adjust to pH 5 6 Bring up to volume with polished D-I H 2 O after adjusting pH Sterilize and cool to 60°C Add 3 5g/L of Gelrite for cell biology ## = Dissolve 0 100 g of Nicotinic Acid, 0 020 g of Thiamine HCL, 0 100 g of Pyridoxine HCL, and 0 400 g of Glycine in 875 00 ml of polished D-I H 2 O in sequence Bring up to volume with polished D-I H 2 O Make in 400 ml portions Thiamine HCL & Pyridoxine HCL are in Dark Desiccator Store for one month, unless contamination or precipitation occurs, then make fresh stock Total Volume (L) = 1 00 560 R Directions: @ = Add after bringing up to volume # = Add after sterilizing and cooling to temp. Dissolve ingredients in D-I H 2 O in sequence Adjust to pH 5.8 with KOH Bring up to volume with D-I H 2 O Sterilize and cool to room temp. Total Volume (L) = 1.00 560 Y Directions @ = Add after bringing up to volume # = Add after sterilizing and cooling to temp Dissolve ingredients in D-I H 2 O in sequence Adjust to pH 5 8 with KOH Bring up to volume with D-I H 2 O Sterilize and cool to room temp ** Autoclave less time because of increased sucrose** Total Volume (L) = 1 00 All publications and patent applications mentioned in the specification are indicative of the level of those skilled in the art to which this invention pertains All publications and patent applications are herein incoφorated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it will be obvious that certain changes and modifications may be practiced within the scope of the appended claims Applicant's or agent's International application No file reference 5718-59- 1 PCT/US99/ INDICATIONS RELATING TO DEPOSITED MICROORGANISM OR OTHER BIOLOGICAL MATERIAL (PCT Rule 13/MS) The indications made below relate to the deposited microorganism or other biological material referred to in the description on page 5, lines 5, 8 and 13 B. IDENTIFICATION OF DEPOSIT Further deposits are identified on an additonal sheet F Name of depository institution American Type Culture Collection Address of depositary institution (including postal code and country) 10801 University Blvd. Manassas, VA 20110-2209 USA Date of deposit Accession Number 21 August 1998 (21.08.98) 98843 C. ADDITIONAL INDICATIONS (leave blank if not applicable) This information is continued on an additional sheet I I Accession No. 98754 - page 5, lines 5, 8 and 13 - Date of deposit : 26 May 1998 (26.05.98) D. DESIGNATED STATES FOR WHICH INDICATIONS ARE MADE (if the indicators are not for all designated States) E. SEPARATE FURNISHING OF INDICATIONS (leave blank if not applicable) The indications listed below will be submitted to the International Bureau later (specify the general nature of the indications e g , "Accession Number of Deposit") For receiving Office use only For International Bureau use only Γ~1 This sheet was received with the international application CH This sheet was received with the International Bureau on Authorized officer Authorized officer 55A Form PCT/RO/134 (July 1998)

Claims: THAT WHICH IS CLAIMED 1 An isolated protein having the amino acid sequence selected from the group consisting of a) an amino acid sequence of a maize replication protein A large subunit, b) an amino acid an amino acid sequence of a plant replication protein A middle subunit, c) an amino acid sequence set forth in SEQ ID NO 2, SEQ D NO 4, SEQ ID NO 12, SEQ ID NO 14, SEQ ID NO 16, SEQ ID NO 18, SEQ ID NO 20, and SEQ ID NO 22, d) an amino acid sequence having substantial identity to an amino acid sequence of a), b), or c), e) an amino acid sequence comprising at least 20 contiguous residues of an amino acid sequence of a), b, or c), f) a variant of an amino acid sequence of a), b, or c) 2 An isolated nucleotide sequence selected from the group consisting of a) a nucleotide sequence encoding a maize replication protein A (RPA) large subunit, b) a nucleotide sequence encoding a plant replication protein A (RPA) middle subunit, c) a nucleotide sequence set forth in SEQ ID NO 1, SEQ ID NO 3, SEQ ID NO 11, SEQ ID NO 13, SEQ ID NO 15, SEQ ID NO 17, SEQ ID NO 19, and SEQ ID NO 21, d) a nucleotide sequence comprising at least 20 contiguous nucleotides of a nucleotide sequence of a) b), or c), e) an antisense nucleotide sequence corresponding to a nucleotide sequence of a), b), or c), f) a nucleotide sequence that hybridizes to the nucleotide sequences of a), b), or c) under stringent conditions, and 56 g) a nucleotide sequence that encodes an amino acid sequence according to claim 1. 3 A DNA construct comprising a nucleotide sequence according to claim 2 wherein said nucleotide sequence is operably linked to a promoter that drives expression in a plant cell 4 The DNA construct of claim 3, wherein said promoter is a tissue- preferred promoter 5 The DNA construct of claim 4, wherein said promoter is a pathogen-inducible promoter 6 The DNA construct of claim 5, wherein said nucleotide sequence is an antisense sequence 7 The DNA construct of claim 3, wherein said promoter is a constitutive promoter 8 A method for enhancing homologous recombination in a plant cell, said method comprising transforming said plant cell with at least one nucleotide sequence operably linked to a heterologous promoter that drives expression in a plant cell, said nucleotide sequence selected from the group consisting of a) a nucleotide sequence encoding a maize replication protein A (RPA) large subunit, b) a nucleotide sequence encoding a plant replication protein A (RPA) middle subunit, c) a nucleotide sequence set forth in SEQ ID NO 1, SEQ ID NO 3, SEQ ID NO 11, SEQ ID NO 13, SEQ ID NO 15, SEQ ID NO 17, SEQ ID NO 19, and SEQ ID NO 21, d) a nucleotide sequence comprising at least 20 contiguous nucleotides of a nucleotide sequence of a) b), or c), 57 e) a nucleotide sequence that hybridizes to the nucleotide sequences of a), b), or c) under stringent conditions, and f) a nucleotide sequence that encodes an amino acid sequence according to claim 1 9 The method of claim 8, wherein said promoter is a constitutive promoter 10 The method of claim 9, wherein said promoter is an ubiquitin promoter 11 A method for increasing pathogen resistance in a plant cell, method comprising transforming said plant cell with at least one nucleotide sequence operably linked to a pathogen-inducible promoter said nucleotide sequence selected from the group consisting of a) an antisense nucleotide sequence corresponding to a maize replication protein A large subunit, and b) an antisense nucleotide sequence corresponding to a plant replication protein A middle subunit 12 A transformed plant cell having stably incorporated into its genome at least one nucleotide sequence, said nucleotide sequence operably linked to a heterologous promoter that drives expression in a plant cell, wherein said nucleotide sequence is selected from the group consisting of a) a nucleotide sequence encoding a maize replication protein A (RPA) large subunit, b) a nucleotide sequence encoding a plant replication protein A (RPA) middle subunit, c) a nucleotide sequence set forth in SEQ ID NO 1, SEQ ID NO 3, SEQ ID NO 11, SEQ ID NO 13, SEQ ID NO 15, SEQ ID NO 17, SEQ ID NO 19, and SEQ ID NO 21, d) a nucleotide sequence comprising at least 20 contiguous nucleotides of a nucleotide sequence of a) b), or c), 58 e) an antisense nucleotide sequence corresponding to a nucleotide sequence of a), b), or c), f) a nucleotide sequence that hybridizes to the nucleotide sequences of a), b), or c) under stringent conditions, and g) a nucleotide sequence that encodes an amino acid sequence according to claim 1 13 A transformed plant having stably incorporated into its genome at least one nucleotide sequence, said nucleotide sequence operably linked to a heterologous promoter that drives expression in a plant cell, wherein said nucleotide sequence is selected from the group consisting of a) a nucleotide sequence encoding a maize replication protein A (RPA) large subunit, b) a nucleotide sequence encoding a plant replication protein A (RPA) middle subunit, c) a nucleotide sequence set forth in SEQ ID NO 1, SEQ ID NO 3, SEQ ID NO 11, SEQ ID NO 13, SEQ ID NO 15, SEQ ID NO 17, SEQ ID NO 19, and SEQ ID NO 21, d) a nucleotide sequence comprising at least 20 contiguous nucleotides of a nucleotide sequence of a) b), or c), e) an antisense nucleotide sequence corresponding to a nucleotide sequence of a), b), or c), f) a nucleotide sequence that hybridizes to the nucleotide sequences of a), b), or c) under stringent conditions, and g) a nucleotide sequence that encodes an amino acid sequence according to claim 1 14 Seed of the plant of claim 13 15 The plant claim 13, wherein said plant is a monocot 16 The plant of claim 15, wherein said monocot is maize, wheat, rice, barley, sorghum, or rye 59 17 The plant of claim 13, wherein said plant is a dicot 18 The plant of claim 17, wherein said dicot is selected from the group consisting of soybean, canola, sunflower, alfalfa, or safflower 19 Seed of the plant of claim 17 20 A method for modulating DNA metabolism in a plant cell, said method comprising transforming said plant cell with at least one nucleotide sequence operably linked to a promoter wherein said nucleotide sequence is selected from the group consisting of a) a nucleotide sequence encoding a maize replication protein A (RPA) large subunit, b) a nucleotide sequence encoding a plant replication protein A (RPA) middle subunit, c) a nucleotide sequence set forth in SEQ ID NO 1, SEQ ID NO 3, SEQ ID NO 1 1, SEQ ID NO 13, SEQ ID NO 15, SEQ ID NO 17, SEQ ID NO 19, and SEQ ID NO. 21, d) a nucleotide sequence comprising at least 20 contiguous nucleotides of a nucleotide sequence of a) b), or c), e) an antisense nucleotide sequence corresponding to a nucleotide sequence of a), b), or c), f) a nucleotide sequence that hybridizes to the nucleotide sequences of a), b), or c) under stringent conditions, and g) a nucleotide sequence that encodes an amino acid sequence according to claim 1 21 A method for influencing cell cycle in a plant cell, said method comprising transforming said plant cell with at least one nucleotide sequence operably linked to a promoter wherein said nucleotide sequence is selected from the group consisting of 60 a) a nucleotide sequence encoding a maize replication protein A (RPA) large subunit, b) a nucleotide sequence encoding a plant replication protein A (RPA) middle subunit, c) a nucleotide sequence set forth in SEQ ID NO 1, SEQ ID NO 3, SEQ ID NO 11, SEQ ID NO 13, SEQ ID NO 15, SEQ ID NO 17, SEQ ID NO 19, and SEQ ID NO 21, d) a nucleotide sequence comprising at least 20 contiguous nucleotides of a nucleotide sequence of a) b), or c), e) an antisense nucleotide sequence corresponding to a nucleotide sequence of a), b), or c), f) a nucleotide sequence that hybridizes to the nucleotide sequences of a), b), or c) under stringent conditions, and g) a nucleotide sequence that encodes an amino acid sequence according to claim 1 61

Inventors: MAHAJAN PRAMOD, MAHAJAN, PRAMOD
Applicants: MAHAJAN PRAMOD, PIONEER HI BRED INT, MAHAJAN, PRAMOD, PIONEER HI-BRED INTERNATIONAL, INC.
Application year: 1999
Main classification: C12N15
IPC codes: A01H5, C07K14, C12N5, C12N15, C12Q1