bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence That Barley 3-Hydroxy-3-Methylglutaryl-Coenzyme A Reductase Kinase Is a Member of the Sucrose Nonfermenting-1-Related Protein Kinase Family
Authors: Barker JHA. , Slocombe S. P. , Ball K. L. , Hardie D. G. , Shewry P. R. , Halford N. G. 
Published: July 2002

Abstract
A protein kinase was partially purified from barley (Hordeum vulgare L. cv Sundance) endosperm by ammonium sulfate fractionation, followed by ion-exchange, Reactive Blue, Mono-Q, and phosphocellulose chromatography. It was shown to phosphorylate Arabidopsis 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase and a synthetic peptide that was shown previously to act as a substrate for HMG-CoA reductase kinase purified from cauliflower, confirming it to be barley HMG-CoA reductase kinase. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the partially purified preparation showed the presence of a polypeptide with an approximate relative molecular weight (Mr) of 60,000, which is the size predicted for the barley sucrose nonfermenting-1 (SNF1)-related protein kinases BKIN2 and BKIN12. Antisera were raised to a rye (Secale cereale L.) SNF1-related protein kinase (RKIN1) expressed in Escherichia coli as a fusion with maltose-binding protein and to a synthetic peptide with a sequence that is conserved in, and specific to, plant members of the SNF1-related protein kinase family. The maltose-binding protein-RKIN1 fusion protein antiserum recognized a doublet of polypeptides with an approximate Mr of 60,000 in crude endosperm extracts and a single polypeptide in root extracts, which co-migrated with the smaller polypeptide in the endosperm doublet. Both antisera recognized a polypeptide with an approximate Mr of 60,000 in the partially purified protein kinase preparation, suggesting strongly that barley HMG-CoA reductase kinase is a member of the SNF1-related protein kinase family.
Maize Phenylalanine Ammonia-Lyase Has Tyrosine Ammonia-Lyase Activity
Authors: Rosler J. , Krekel F. , Amrhein N. , Schmid J. 
Published: July 2002

Abstract
A full-length cDNA encoding phenylalanine ammonia-lyase (PAL) from Zea mays L. was isolated and the coding region was expressed in Escherichia coli as a C-terminal fusion to glutathione S-transferase. After purification by glutathione-Sepharose chromatography, the glutathione S-transferase moiety was cleaved off and the resulting PAL enzyme analyzed. In contrast to PAL from dicots, this maize PAL isozyme catalyzed the deamination of both L-phenylalanine (PAL activity) and L-tyrosine (tyrosine ammonialyase activity). These results provide unequivocal proof that PAL and tyrosine ammonia-lyase activities reside in the same polypeptide. In spite of large differences in the Michaelis constant and turnover number of the two activities, their catalytic efficiencies are very similar. Also, both activities have the same pH and temperature optima. These results imply that maize can produce p-coumaric acid from both phenylalanine and tyrosine.
Structure of the CAC1 Gene and in Situ Characterization of Its Expression (The Arabidopsis thaliana Gene Coding for the Biotin-Containing Subunit of the Plastidic Acetyl-Coenzyme A Carboxylase)
Authors: Ke J. , Choi J. K. , Smith M. , Horner H. T. , Nikolau B. J. , Wurtele E. S. 
Published: July 2002

Abstract
The CAC1 gene of Arabidopsis thaliana that codes for the biotin carboxyl-carrier subunit of the heteromeric acetyl-coenzyme A carboxylase was isolated and sequenced. CAC1 is a single-copy gene interrupted by six introns. Subcellular immunogold labeling indicates that the biotin carboxyl-carrier subunit is localized in the stroma of the plastids and chloroplasts. The CAC1 mRNA accumulates throughout developing embryos and ovules of siliques at a time of rapid growth and oil accumulation (7 d after flowering), but is present at much lower levels in wall cells and central septal cells of the silique. Immunolocalization studies show that the pattern of accumulation of the biotin carboxyl-carrier subunit within the siliques and leaves is similar to that of the CAC1 mRNA. These observations indicate that the cellular pattern of biotin carboxyl-carrier protein accumulation in the developing silique may be determined by the transcriptional activity of the CAC1 gene.
Immunological Detection of Potential Signal-Transduction Proteins Expressed during Wheat Somatic Tissue Culture
Authors: Nato A. , Mirshahi A. , Tichtinsky G. , Mirshahi M. , Faure J. P. , Lavergne D. , De Buyser J. , Jean C. , Ducreux G. , Henry Y. 
Published: July 2002

Abstract
An immunochemical approach was used to detect the expression of putative guanine nucleotide-binding proteins (G-proteins), arrestin, and nucleoside diphosphate kinases during wheat (Triticum aestivum) tissue culture initiated from immature embryos. Both the soluble and membrane extracts from the immature embryos revealed bands of 58, 40, and 16 kD with antibodies to G-protein (α- subunit), arrestin, and nucleoside diphosphate kinase, respectively. These proteins were overexpressed in vitro in both nonembryogenic callus and embryogenic cultures. An additional soluble protein (32 kD) was detected by anti-Gα- antibodies in cultured tissues but not in immature embryos, suggesting a possible function in cell multiplication. Moreover, somatic embryogenesis was associated with the appearance of a 29-kD protein reactive with anti-arrestin antibodies, both in soluble and membrane fractions. Tissue-cultured genetic stocks of Chinese Spring wheat, including the disomic, 36 ditelosomic, and 6 nullisomic-tetrasomic wheat lines, were used to ascertain the chromosomal location of the genes encoding the 29-kD arrestin-like protein. The lack of a signal with the nonembryogenic ditelosomic 3 D short chromosome arm line suggests that the 3 D long chromosome arm possesses at least one gene involved in the expression of the 29-kD protein. The putative role of the 29-kD protein in signal-transduction regulating embryogenesis is discussed.
Light Regulation of the Abundance of mRNA Encoding a Nucleolin-Like Protein Localized in the Nucleoli of Pea Nuclei
Authors: Tong C. G. , Reichler S. , Blumenthal S. , Balk J. , Hsieh H. L. , Roux S. J. 
Published: July 2002

Abstract
A cDNA encoding a nucleolar protein was selected from a pea (Pisum sativum) plumule library, cloned, and sequenced. The translated sequence of the cDNA has significant percent identity to Xenopus laevis nucleolin (31%), the alfalfa (Medicago sativa) nucleolin homolog (66%), and the yeast (Saccharomyces cerevisiae) nucleolin homolog (NSR1) (28%). It also has sequence patterns in its primary structure that are characteristic of all nucleolins, including an N-terminal acidic motif, RNA recognition motifs, and a C-terminal Gly- and Arg-rich domain. By immunoblot analysis, the polyclonal antibodies used to select the cDNA bind selectively to a 90kD protein in purified pea nuclei and nucleoli and to an 88-kD protein in extracts of Escherichia coli expressing the cDNA. In immunolocalization assays of pea plumule cells, the antibodies stained primarily a region surrounding the fibrillar center of nucleoli, where animal nucleolins are typically found. Southern analysis indicated that the pea nucleolin-like protein is encoded by a single gene, and northern analysis showed that the labeled cDNA binds to a single band of RNA, approximately the same size as the cDNA. After irradiation of etiolated pea seedlings by red light, the mRNA level in plumules decreased during the 1st hour and then increased to a peak of six times the 0-h level at 12 h. Far-red light reversed this effect of red light, and the mRNA accumulation from red/far-red light irradiation was equal to that found in the dark control. This indicates that phytochrome may regulate the expression of this gene.
Protein Phosphorylation as a Mechanism for Osmotic-Stress Activation of Sucrose-Phosphate Synthase in Spinach Leaves
Authors: Toroser D. , Huber S. C. 
Published: July 2002

Abstract
Experiments were performed to investigate the mechanism of sucrose-phosphate synthase (SPS) activation by osmotic stress in darkened spinach (Spinacia oleracea L.) leaves. The activation was stable through immunopurification and was not the result of an increased SPS protein level. The previously described Ca2+, independent peak III kinase, obtained by ion-exchange chromatography, is confirmed to be the predominant enzyme catalyzing phosphorylation and inactivation of dephosphoserine-158-SPS. A new, Ca2+-dependent SPS-protein kinase activity (peak IV kinase) was also resolved and shown to phosphorylate and activate phosphoserine-158-SPS in vitro. The peak IV kinase also phosphorylated a synthetic peptide (SP29) based on the amino acid sequence surrounding serine-424, which also contains the motif described for the serine-158 regulatory phosphorylation site; i.e. basic residues at P-3 and P-6 and a hydrophobic residue at P-5. Peak IV kinase had a native molecular weight of approximately 150,000 as shown by gel filtration. The SP29 peptide was not phosphorylated by the inactivating peak III kinase. Osmotically stressed leaves showed increased peak IV kinase activity with the SP29 peptide as a substrate. Tryptic 32P-phosphopeptide analysis of SPS from excised spinach leaves fed [32P]inorganic P showed increased phosphorylation of the tryptic peptide containing serine-424. Therefore, at least part of the osmotic stress activation of SPS in dark leaves results from phosphorylation of serine-424 catalyzed by a Ca2+-dependent, 150-kD protein kinase.
Stepwise Photoinhibition of Photosystem II1
Authors: Mulo Paula , Laakso Susana , Mäenpää Pirkko , Aro Eva-Mari 
Published: July 2002

Abstract
Several mutant strains ofSynechocystis sp. PCC 6803 with large deletions in the D-E loop of the photosystem II (PSII) reaction center polypeptide D1 were subjected to high light to investigate the role of this hydrophilic loop in the photoinhibition cascade of PSII. The tolerance of PSII to photoinhibition in the autotrophic mutant ΔR225-F239 (PD), when oxygen evolution was monitored with 2,6-dichloro-p-benzoquinone and the equal susceptibility compared with control when monitored with bicarbonate, suggested an inactivation of the QB-binding niche as the first event in the photoinhibition cascade in vivo. This step in PD was largely reversible at low light without the need for protein synthesis. Only the next event, inactivation of QA reduction, was irreversible and gave a signal for D1 polypeptide degradation. The heterotrophic deletion mutants ΔG240-V249 and ΔR225-V249 had severely modified QB pockets, yet exhibited high rates of 2,6-dichloro-p-benzoquinone-mediated oxygen evolution and less tolerance to photoinhibition than PD. Moreover, the protein-synthesis-dependent recovery of PSII from photoinhibition was impaired in the ΔG240-V249 and ΔR225-V249 mutants because of the effects of the mutations on the expression of the psbA-2gene. No specific sequences in the D-E loop were found to be essential for high rates of D1 polypeptide degradation.
Expression Patterns Conferred by Tyrosine/Dihydroxyphenylalanine Decarboxylase Promoters from Opium Poppy Are Conserved in Transgenic Tobacco1
Authors: Facchini Peter J. , Penzes-Yost Catherine , Samanani Nailish , Kowalchuk Brett 
Published: July 2002

Abstract
Opium poppy (Papaver somniferum) contains a large family of tyrosine/dihydroxyphenylalanine decarboxylase (tydc) genes involved in the biosynthesis of benzylisoquinoline alkaloids and cell wall-bound hydroxycinnamic acid amides. Eight members from two distinct gene subfamilies have been isolated, tydc1,tydc4, tydc6, tydc8, andtydc9 in one group and tydc2,tydc3, and tydc7 in the other. Thetydc8 and tydc9 genes were located 3.2 kb apart on one genomic clone, suggesting that the family is clustered. Transcripts for most tydc genes were detected only in roots. Only tydc2 and tydc7 revealed expression in both roots and shoots, and TYDC3 mRNAs were the only specific transcripts detected in seedlings. TYDC1, TYDC8, and TYDC9 mRNAs, which occurred in roots, were not detected in elicitor-treated opium poppy cultures. Expression of tydc4, which contains a premature termination codon, was not detected under any conditions. Five tydc promoters were fused to the β-glucuronidase (GUS) reporter gene in a binary vector. All constructs produced transient GUS activity in microprojectile-bombarded opium poppy and tobacco (Nicotiana tabacum) cell cultures. The organ- and tissue-specific expression pattern oftydc promoter-GUS fusions in transgenic tobacco was generally parallel to that of corresponding tydc genes in opium poppy. GUS expression was most abundant in the internal phloem of shoot organs and in the stele of roots. Select tydcpromoter-GUS fusions were also wound induced in transgenic tobacco, suggesting that the basic mechanisms of developmental and inducibletydc regulation are conserved across plant species.
The Responses of Cytochrome Redox State and Energy Metabolism to Dehydration Support a Role for Cytoplasmic Viscosity in Desiccation Tolerance
Authors: Leprince Olivier , Hoekstra Folkert A. 
Published: July 2002

Abstract
To characterize the depression of metabolism in anhydrobiotes, the redox state of cytochromes and energy metabolism were studied during dehydration of soaked cowpea (Vigna unguiculata) cotyledons and pollens ofTypha latifolia and Impatiens glandulifera. Between water contents (WC) of 1.0 and 0.6 g H2O/g dry weight (g/g), viscosity as measured by electron spin resonance spectroscopy increased from 0.15 to 0.27 poise. This initial water loss was accompanied by a 50% decrease in respiration rates, whereas the adenylate energy charge remained constant at 0.8, and cytochrome c oxidase (COX) remained fully oxidized. From WC of 0.6 to 0.2 g/g, viscosity increased exponentially. The adenylate energy charge declined to 0.4 in seeds and 0.2 in pollen, whereas COX became progressively reduced. At WC of less than 0.2 g/g, COX remained fully reduced, whereas respiration ceased. When dried under N2, COX remained 63% reduced in cotyledons until WC was 0.7 g/g and was fully reduced at 0.2 g/g. During drying under pure O2, the pattern of COX reduction was similar to that of air-dried tissues, although the maximum reduction was 70% in dried tissues. Thus, at WC of less than 0.6 g/g, the reduction of COX probably originates from a decreased O2 availability as a result of the increased viscosity and impeded diffusion. We suggest that viscosity is a valuable parameter to characterize the relation between desiccation and decrease in metabolism. The implications for desiccation tolerance are discussed.
Overexpression of Glutathione Synthetase in Indian Mustard Enhances Cadmium Accumulation and Tolerance1
Authors: Liang Zhu Yong , Pilon-Smits Elizabeth A.H. , Jouanin Lise , Terry Norman 
Published: July 2002

Abstract
An important pathway by which plants detoxify heavy metals is through sequestration with heavy-metal-binding peptides called phytochelatins or their precursor, glutathione. To identify limiting factors for heavy-metal accumulation and tolerance, and to develop transgenic plants with an increased capacity to accumulate and/or tolerate heavy metals, the Escherichia coli gshII gene encoding glutathione synthetase (GS) was overexpressed in the cytosol of Indian mustard (Brassica juncea). The transgenic GS plants accumulated significantly more Cd than the wild type: shoot Cd concentrations were up to 25% higher and total Cd accumulation per shoot was up to 3-fold higher. Moreover, the GS plants showed enhanced tolerance to Cd at both the seedling and mature-plant stages. Cd accumulation and tolerance were correlated with thegshII expression level. Cd-treated GS plants had higher concentrations of glutathione, phytochelatin, thiol, S, and Ca than wild-type plants. We conclude that in the presence of Cd, the GS enzyme is rate limiting for the biosynthesis of glutathione and phytochelatins, and that overexpression of GS offers a promising strategy for the production of plants with superior heavy-metal phytoremediation capacity.
A Splice Site Mutant of Maize Activates Cryptic Splice Sites, Elicits Intron Inclusion and Exon Exclusion, and Permits Branch Point Elucidation
Authors: Lal Shailesh , Choi Jae-Hyuk , Shaw Janine R. , Hannah L. Curtis 
Published: July 2002

Abstract
DNA sequence analysis of thebt2-7503 mutant allele of the maizebrittle-2 gene revealed a point mutation in the 5′ terminal sequence of intron 3 changing GT to AT. This lesion completely abolishes use of this splice site, activates two cryptic splice sites, and alters the splicing pattern from extant splice sites. One activated donor site, located nine nt 5′ to the normal splice donor site, begins with the dinucleotide GC. While non-consensus, this sequence still permits both trans-esterification reactions of pre-mRNA splicing. A second cryptic site located 23 nt 5′ to the normal splice site and beginning with GA, undergoes the first trans-esterification reaction leading to lariat formation, but lacks the ability to participate in the second reaction. Accumulation of this splicing intermediate and use of an innovative reverse transcriptase-polymerase chain reaction technique (J. Vogel, R.H. Wolfgang, T. Borner [1997] Nucleic Acids Res 25: 2030–2031) led to the identification of 3′ intron sequences needed for lariat formation. In most splicing reactions, neither cryptic site is recognized. Most mature transcripts include intron 3, while the second most frequent class lacks exon 3. Traditionally, the former class of transcripts is taken as evidence for the intron definition of splicing, while the latter class has given credence to the exon definition of splicing.
Nitrogenase Activity in Alnus incana Root Nodules. Responses to O2 and Short-Term N2Deprivation
Authors: Lundquist Per-Olof 
Published: July 2002

Abstract
O2 and host-microsymbiont interactions are key factors affecting the physiology of N2-fixing symbioses. To determine the relationship among nitrogenase activity of Frankia-Alnus incana root nodules, O2 concentration, and short-term N2 deprivation, intact nodulated roots were exposed to various O2 pressures (pO2) and Ar:O2 in a continuous flow-through system. Nitrogenase activity (H2 production) occurred at a maximal rate at 20% O2. Exposure to short-term N2 deprivation in Ar:O2 carried out at either 17%, 21%, or 25% O2 caused a decline in the nitrogenase activity at 21% and 25% O2 by 12% and 25%, respectively. At 21% O2, nitrogenase activity recovered to initial activity within 60 min. The decline rate was correlated with the degree of inhibition of N2 fixation. Respiration (net CO2evolution) decreased in response to the N2 deprivation at all pO2 values and did not recover during the time in Ar:O2. Increasing the pO2 from 21% to 25% and decreasing the pO2 from 21% to 17% during the decline further decreased rather than stimulated nitrogenase activity, showing that the decline was not due to O2 limitation. The decline was possibly due to a temporary disturbance in the supply of reductant to nitrogenase with a partial O2 inhibition of nitrogenase at 25% O2. These results are consistent with a fixed O2 diffusion barrier in A. incana root nodules, and show that A. incana nodules differ from legume nodules in the response of the nitrogenase activity to O2 and N2 deprivation.
Auxin Metabolism in the Root Apical Meristem
Authors: Kerk Nancy M. , Jiang Keni , Feldman Lewis J. 
Published: July 2002

Abstract
Within the root meristem of flowering plants is a group of mitotically inactive cells designated the quiescent center (QC). Recent work links the quiescent state to high levels of the growth regulator auxin that accumulates in the QC via polar transport. This in turn results in elevated levels of the enzyme ascorbic acid oxidase (AAO), resulting in a reduction of ascorbic acid (AA) within the QC and mitotic quiescence. We present evidence for additional interactions between auxin, AAO, and AA, and report that, in vitro, AAO oxidatively decarboxylates auxin, suggesting a mechanism for regulating auxin levels within the QC. We also report that oxidative decarboxylation occurs at the root tip and that an intact root cap must be present for this metabolic event to occur. Finally, we consider how interaction between auxin and AAO may influence root development by regulating the formation of the QC.
Superoxide Production by Plant Homologues of the gp91phox NADPH Oxidase. Modulation of Activity by Calcium and by Tobacco Mosaic Virus Infection
Authors: Sagi Moshe , Fluhr Robert 
Published: July 2002

Abstract
Genes encoding homologs of the gp91phox subunit of the plasma membrane NADPH oxidase complex have been identified in plants and are hypothesized to be a source of reactive oxygen species during defense responses. However, the direct involvement of the gene products in superoxide (O2 −) production has yet to be shown. A novel activity gel assay based on protein fractionation in native or sodium dodecyl sulfate (SDS)-denaturing polyacrylamide gels was developed. In native polyacrylamide gel electrophoresis, one or two major O2 −-producing formazan bands were detected in tomato (Lycopersicum esculentum Mill. cv Moneymaker) and tobacco (Nicotiana tabacum var. Samsun, NN) plasma membranes, respectively. Denaturing fractionation of tomato and tobacco plasma membrane in SDS-polyacrylamide gel electrophoresis, followed by regeneration of the in-gel activity, revealed NADPH-dependent O2 −-producing formazan bands of 106-, 103-, and 80- to 75-kD molecular masses. The SDS and native activity bands were dependent on NADPH and completely inhibited by diphenylene iodonium or CuZn- O2 − dismutase, indicating that the formazan precipitates were due to reduction by O2 − radicals catalyzed by an NADPH-dependent flavin containing enzyme. The source of the plasma membrane activity bands was confirmed by their cross-reaction with antibody prepared from the C terminus of the tomato gp91phoxhomolog. Membrane extracts as well as the in-gel NADPH oxidase activities were stimulated in the presence of Ca2+. In addition, the relative activity of the gp91phox homolog was enhanced in the plasma membrane of tobacco mosaic virus-infected leaves. Thus, in contrast to the mammalian gp91phox, the plant homolog can produce O2 − in the absence of additional cytosolic components and is stimulated directly by Ca2+.
Differential chemical labeling of the AlcR DNA‐binding domain from Aspergillas nidulans versus its complex with a 16‐mer DNA target: Identification of an essential tryptophan involved in the recognition and the interaction with the nucleic acid
Authors: Marie Gérald , Serani Laurent , Laprévote Olivier , Cahuzac Bertrand , Guittet Eric , Felenbok Béatrice 
Published: July 2002

AbstractDNA binding of the ethanol regulon transcription factor AlcR from Aspergillus nidulans was shown to involve a consensus basic region as in the other zinc cluster proteins. However, additional interactions between some residues and DNA were suspected, among which were a hypothetic hydrophobic interaction between Trp45 and the T residue of the consensus TGCGG sequence. In the present study, the differential chemical labeling of both the free protein and the protein/DNA complex showed significantly different behaviors of the three tryptophan residues comprised in the AlcR sequence toward the Koshland reagent. The spectacular decreased reaction rate for Trp45 within the complex confirmed the location of this residue at the protein/DNA interface. A similar result obtained with Trp53, an amino acid present at the C‐terminal side of AlcR, also indicated its involvement in the DNA recognition. In contrast, the formation of the complex accompanied by an allosteric rearrangement allowed the Trp36 to be much more exposed to the solvent than in the free protein. These data provide additional evidence that the unique specificity of AlcR among the zinc binuclear cluster family results in new types of interactions between AlcR and its cognate targets. From a methodological point of view, the approach of differential chemical labeling combined with mass spectrometric analyses proved to be an interesting tool for the recognition of hydrophobic interactions between the tryptophan residues of a protein and its macromolecular target.