bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cloning and Characterization of the Abscisic Acid-Specific Glucosyltransferase Gene from Adzuki Bean Seedlings
Authors: Xu Zheng-Jun , Nakajima Masatoshi , Suzuki Yoshihito , Yamaguchi Isomaro 
Published: July 2002

Abstract
The glycosylated forms of abscisic acid (ABA) have been identified from many plant species and are known to be the forms of ABA-catabolism, although their (physiological) roles have not yet been elucidated. ABA-glucosyltransferase (-GTase) is thought to play a key role in the glycosylation of ABA. We isolated an ABA-inducible GTase gene from UDP-GTase homologs obtained from adzuki bean (Vigna angularis) seedlings. The deduced amino acid sequence (accession no. AB065190) showed 30% to 44% identity with the known UDP-GTase homologs. The recombinant protein with a glutathioneS-transferase-tag was expressed in Escherichia coli and showed enzymatic activity in an ABA-specific manner. The enzymatic activity was detected over a wide pH range from 5.0 to 9.0, the optimum range being between pH 6.0 and 7.3, in a citrate and Tris-HCl buffer. The product from racemic ABA and UDP-d-glucose was identified to be ABA-GE by gas chromatography/mass spectrometry. The recombinant GTase (rAOG) converted 2-trans-(+)-ABA better than (+)-S-ABA and (−)-R-ABA. Although trans-cinnamic acid was slightly converted to its conjugate by the GTase, (−)-PA was not at all. The mRNA level was increased by ABA application or by water stress and wounding. We suggest that the gene encodes an ABA-specific GTase and that its expression is regulated by environmental stress.
SOS4, A Pyridoxal Kinase Gene, Is Required for Root Hair Development in Arabidopsis
Authors: Shi Huazhong , Zhu Jian-Kang 
Published: July 2002

Abstract
Root hair development in plants is controlled by many genetic, hormonal, and environmental factors. A number of genes have been shown to be important for root hair formation. Arabidopsissalt overly sensitive 4 mutants were originally identified by screening for NaCl-hypersensitive growth. TheSOS4 (Salt Overly Sensitive 4) gene was recently isolated by map-based cloning and shown to encode a pyridoxal (PL) kinase involved in the production of PL-5-phosphate, which is an important cofactor for various enzymes and a ligand for certain ion transporters. The root growth of sos4 mutants is slower than that of the wild type. Microscopic observations revealed thatsos4 mutants do not have root hairs in the maturation zone. The sos4 mutations block the initiation of most root hairs, and impair the tip growth of those that are initiated. The root hairless phenotype of sos4 mutants was complemented by the wild-type SOS4 gene. SOS4promoter-β-glucuronidase analysis showed thatSOS4 is expressed in the root hair and other hair-like structures. Consistent with SOS4 function as a PL kinase, in vitro application of pyridoxine and pyridoxamine, but not PL, partially rescued the root hair defect in sos4 mutants. 1-Aminocyclopropane-1-carboxylic acid and 2,4-dichlorophenoxyacetic acid treatments promoted root hair formation in both wild-type andsos4 plants, indicating that geneticallySOS4 functions upstream of ethylene and auxin in root hair development. The possible role of SOS4 in ethylene and auxin biosynthesis is discussed.
Genome Properties of the Diatom Phaeodactylum tricornutum
Authors: Scala Simona , Carels Nicolas , Falciatore Angela , Chiusano Maria Luisa , Bowler Chris 
Published: July 2002

Abstract
Diatoms are a ubiquitous class of microalgae of extreme importance for global primary productivity and for the biogeochemical cycling of minerals such as silica. However, very little is known about diatom cell biology or about their genome structure. For diatom researchers to take advantage of genomics and post-genomics technologies, it is necessary to establish a model diatom species.Phaeodactylum tricornutum is an obvious candidate because of its ease of culture and because it can be genetically transformed. Therefore, we have examined its genome composition by the generation of approximately 1,000 expressed sequence tags. Although more than 60% of the sequences could not be unequivocally identified by similarity to sequences in the databases, approximately 20% had high similarity with a range of genes defined functionally at the protein level. It is interesting that many of these sequences are more similar to animal rather than plant counterparts. Base composition at each codon position and GC content of the genome were compared with Arabidopsis, maize (Zea mays), andChlamydomonas reinhardtii. It was found that distribution of GC within the coding sequences is as homogeneous inP. tricornutum as in Arabidopsis, but with a slightly higher GC content. Furthermore, we present evidence that the P. tricornutum genome is likely to be small (less than 20 Mb). Therefore, this combined information supports the development of this species as a model system for molecular-based studies of diatom biology. The nucleotide sequence data reported has been deposited in GenBank Nucleotide Sequence Database (dbEST section) under accession nos. BI306757 through BI307753.
Phosphite, an Analog of Phosphate, Suppresses the Coordinated Expression of Genes under Phosphate Starvation
Authors: Varadarajan Deepa K. , Karthikeyan Athikkattuvalasu S. , Matilda Paino Durzo , Raghothama Kashchandra G. 
Published: July 2002

Abstract
Phosphate (Pi) and its analog phosphite (Phi) are acquired by plants via Pi transporters. Although the uptake and mobility of Phi and Pi are similar, there is no evidence suggesting that plants can utilize Phi as a sole source of phosphorus. Phi is also known to interfere with many of the Pi starvation responses in plants and yeast (Saccharomyces cerevisiae). In this study, effects of Phi on plant growth and coordinated expression of genes induced by Pi starvation were analyzed. Phi suppressed many of the Pi starvation responses that are commonly observed in plants. Enhanced root growth and root to shoot ratio, a hallmark of Pi stress response, was strongly inhibited by Phi. The negative effects of Phi were not obvious in plants supplemented with Pi. The expression of Pi starvation-induced genes such as LePT1, LePT2,AtPT1, and AtPT2 (high-affinity Pi transporters); LePS2 (a novel acid phosphatase);LePS3 and TPSI1 (novel genes); andPAP1 (purple acid phosphatase) was suppressed by Phi in plants and cell cultures. Expression of luciferase reporter gene driven by the Pi starvation-induced AtPT2 promoter was also suppressed by Phi. These analyses showed that suppression of Pi starvation-induced genes is an early response to addition of Phi. These data also provide evidence that Phi interferes with gene expression at the level of transcription. Synchronized suppression of multiple Pi starvation-induced genes by Phi points to its action on the early molecular events, probably signal transduction, in Pi starvation response.
Immunohistochemistry of Active Gibberellins and Gibberellin-Inducible α-Amylase in Developing Seeds of Morning Glory
Authors: Nakayama Akira , Park Seijin , Zheng-Jun Xu , Nakajima Masatoshi , Yamaguchi Isomaro 
Published: July 2002

Abstract
Gibberellins (GAs) in developing seeds of morning glory (Pharbitis nil) were quantified and localized by immunostaining. The starch grains began to be digested after the GA contents had increased and reached a plateau. Immunohistochemical staining with the antigibberellin A1-methyl ester-antiserum, which has high affinity to biologically active GAs, showed that GA1 and/or GA3 were localized around starch grains in the integument of developing young seeds, suggesting the participation of GA-inducible α-amylase in this digestion. We isolated an α-amylase cDNA (PnAmy1) that was expressed in the immature seeds, and using an antibody raised against recombinant protein, it was shown that PnAmy1 was expressed in the immature seeds. GA responsiveness of PnAmy1 was shown by treating the young fruits 9 d after anthesis with GA3. RNA-blot and immunoblot analyses showed that PnAmy1 emerged soon after the rapid increase of GA1/3. An immunohistochemical analysis of PnAmy1 showed that it, like the seed GA1/3, was also localized around starch grains in the integument of developing young seeds. The localization of GA1/3 in the integument coincident with the expression of PnAmy1 suggests that both function as part of a process to release sugars for translocation or for the further development of the seeds.
TheLateral Organ BoundariesGene Defines a Novel, Plant-Specific Gene Family
Authors: Shuai Bin , Reynaga-Peña Cristina G. , Springer Patricia S. 
Published: July 2002

AbstractThe LATERAL ORGAN BOUNDARIES(LOB) gene in Arabidopsis defines a new conserved protein domain. LOB is expressed in a band of cells at the adaxial base of all lateral organs formed from the shoot apical meristem and at the base of lateral roots. LOB encodes a predicted protein that does not have recognizable functional motifs, but that contains a conserved domain (the LOB domain) that is present in 42 other Arabidopsis proteins and in proteins from a variety of other plant species. Proteins showing similarity to the LOB domain were not found outside of plant databases, indicating that this unique protein may play a role in plant-specific processes. Genes encoding LOB domain proteins are expressed in a variety of temporal- and tissue-specific patterns, suggesting that they may function in diverse processes. Loss-of-function LOB mutants have no detectable phenotype under standard growth conditions, suggesting thatLOB is functionally redundant or required during growth under specific environmental conditions. Ectopic expression ofLOB leads to alterations in the size and shape of leaves and floral organs and causes male and female sterility. The expression of LOB at the base of lateral organs suggests a potential role for LOB in lateral organ development.
The Barley MLO Modulator of Defense and Cell Death Is Responsive to Biotic and Abiotic Stress Stimuli
Authors: Piffanelli Pietro , Zhou Fasong , Casais Catarina , Orme James , Jarosch Birgit , Schaffrath Ulrich , Collins Nicholas C. , Panstruga Ralph , Schulze-Lefert Paul 
Published: July 2002

Abstract
Lack of the barley (Hordeum vulgare) seven-transmembrane domain MLO protein confers resistance against the fungal pathogen Blumeria graminis f. sp.hordei (Bgh). To broaden the basis for MLO structure/function studies, we sequenced additionalmlo resistance alleles, two of which confer only partial resistance. Wild-type MLO dampens the cell wall-restricted hydrogen peroxide burst at points of attempted fungal penetration of the epidermal cell wall, and in subtending mesophyll cells, it suppresses a second oxidative burst and cell death. Although theBgh-induced cell death in mlo plants is spatially and temporally separated from resistance, we show that the two processes are linked. Uninoculated mutant mlo plants exhibit spontaneous mesophyll cell death that appears to be part of accelerated leaf senescence. Mlo transcript abundance increases in response to Bgh, rice (Oryza sativa) blast, wounding, paraquat treatment, a wheat powdery mildew-derived carbohydrate elicitor, and during leaf senescence. This suggests a broad involvement of Mlo in cell death protection and in responses to biotic and abiotic stresses.
Methyl Jasmonate Induces Traumatic Resin Ducts, Terpenoid Resin Biosynthesis, and Terpenoid Accumulation in Developing Xylem of Norway Spruce Stems
Authors: Martin Diane , Tholl Dorothea , Gershenzon Jonathan , Bohlmann Jörg 
Published: July 2002

Abstract
Norway spruce (Picea abies L. Karst) produces an oleoresin characterized by a diverse array of terpenoids, monoterpenoids, sesquiterpenoids, and diterpene resin acids that can protect conifers against potential herbivores and pathogens. Oleoresin accumulates constitutively in resin ducts in the cortex and phloem (bark) of Norway spruce stems. De novo formation of traumatic resin ducts (TDs) is observed in the developing secondary xylem (wood) after insect attack, fungal elicitation, and mechanical wounding. Here, we characterize the methyl jasmonate-induced formation of TDs in Norway spruce by microscopy, chemical analyses of resin composition, and assays of terpenoid biosynthetic enzymes. The response involves tissue-specific differentiation of TDs, terpenoid accumulation, and induction of enzyme activities of both prenyltransferases and terpene synthases in the developing xylem, a tissue that constitutively lacks axial resin ducts in spruce. The induction of a complex defense response in Norway spruce by methyl jasmonate application provides new avenues to evaluate the role of resin defenses for protection of conifers against destructive pests such as white pine weevils (Pissodes strobi), bark beetles (Coleoptera, Scolytidae), and insect-associated tree pathogens.
Brassinosteroid-Regulated Gene Expression
Authors: Müssig Carsten , Fischer Sabine , Altmann Thomas 
Published: July 2002

Abstract
Major brassinosteroid (BR) effects such as BR-induced growth are mediated through genomic pathways because RNA synthesis inhibitors and protein synthesis inhibitors interfere with these processes. A limited number of BR-regulated genes have been identified hitherto. The majority of genes (such as BRU1, CycD3,Lin6, OPR3, and TRIP-1) were identified by comparisons of BR-treated versus control-treated plants. However, altered transcript levels after BR application may not reflect normal physiological events. A complementary approach is the comparison of BR-deficient plants versus wild-type plants. No artificial treatments interfere with endogenous signaling pathways, but a subset of phenotypic alterations of phytohormone-deficient plants most probably is secondary. To identify genes that are subject to direct BR regulation, we analyzed CPD antisense anddwf1-6 (cbb1) mutant plants. Both show a mild phenotype in comparison with BR-deficient mutants such ascpd/cbb3, det2, anddwf4. Plants were grown under two different environments to filter out BR deficiency effects that occur only at certain environmental conditions. Finally, we established expression patterns after BR treatment of wild-type and dwf1-6(cbb1) plants. Ideally, a BR-regulated gene displays a dose-response relationship in such a way that a gene with decreased transcript levels in BR-deficient plants is BR inducible and vice versa. Expression profile analysis of above ground part of plants was performed by means of Affymetrix Arabidopsis Genome Arrays.
Molecular Characterization and Evolution of the Protein Phosphatase 2A B′ Regulatory Subunit Family in Plants
Authors: Terol Javier , Bargues Mónica , Carrasco Pedro , Pérez-Alonso Manuel , Paricio Nuria 
Published: July 2002

Abstract
Type 2A serine/threonine protein phosphatases (PP2A) are important components in the reversible protein phosphorylation events in plants and other organisms. PP2A proteins are oligomeric complexes constituted by a catalytic subunit and several regulatory subunits that modulate the activity of these phosphatases. The analysis of the complete genome of Arabidopsis allowed us to characterize four novel genes, AtB′ε, AtB′ζ,AtB′η, and AtB′θ, belonging to the PP2A B′ regulatory subunit family. Because four genes of this type had been described previously, this family is composed of eight members. Reverse transcriptase-polymerase chain reaction experiments showed thatAtB′ε mRNAs are present in all Arabidopsis tissues analyzed, and their levels do not respond significantly to heat stress. Expressed sequence tags corresponding to AtB′ζ,AtB′η, and AtB′θ have been identified, indicating that the new genes are actively transcribed. The genomic organization of this family of PP2A regulatory subunits is reported, as well as its chromosomal location. An extensive survey of the family has been carried out in plants, characterizing B′ subunits in a number of different species, and performing a phylogenetic study that included several B′ regulatory proteins from animals. Our results indicate that the animal and plant proteins have evolved independently, that there is a relationship between the number of B′ isoforms and the complexity of the organism, and that there are at least three main subfamilies of regulatory subunits in plants, which we have named α, η, and κ.
Probing metal ion binding and conformational properties of the colicin E9 endonuclease by electrospray ionization time‐of‐flight mass spectrometry
Authors: van den Bremer Ewald T.J. , Jiskoot Wim , James Richard , Moore Geoffrey R. , Kleanthous Colin , Heck Albert J.R. , Maier Claudia S. 
Published: July 2002

AbstractNano‐electrospray ionization time‐of‐flight mass spectrometry (ESI‐MS) was used to study the conformational consequences of metal ion binding to the colicin E9 endonuclease (E9 DNase) by taking advantage of the unique capability of ESI‐MS to allow simultaneous assessment of conformational heterogeneity and metal ion binding. Alterations of charge state distributions on metal ion binding/release were correlated with spectral changes observed in far‐ and near‐UV circular dichroism (CD) and intrinsic tryptophan fluorescence. In addition, hydrogen/deuterium (H/D) exchange experiments were used to probe structural integrity. The present study shows that ESI‐MS is sensitive to changes of the thermodynamic stability of E9 DNase as a result of metal ion binding/release in a manner consistent with that deduced from proteolysis and calorimetric experiments. Interestingly, acid‐induced release of the metal ion from the E9 DNase causes dramatic conformational instability associated with a loss of fixed tertiary structure, but secondary structure is retained. Furthermore, ESI‐MS enabled the direct observation of the noncovalent protein complex of E9 DNase bound to its cognate immunity protein Im9 in the presence and absence of Zn2+. Gas‐phase dissociation experiments of the deuterium‐labeled binary and ternary complexes revealed that metal ion binding, not Im9, results in a dramatic exchange protection of E9 DNase in the complex. In addition, our metal ion binding studies and gas‐phase dissociation experiments of the ternary E9 DNase‐Zn2+‐Im9 complex have provided further evidence that electrostatic interactions govern the gas phase ion stability.
Implications of secondary structure prediction and amino acid sequence comparison of class I and class II phosphoribosyl diphosphate synthases on catalysis, regulation, and quaternary structure
Authors: Krath Britta N. , Hove‐Jensen Bjarne 
Published: July 2002

AbstractSpinach 5‐phospho‐d‐ribosyl α‐1‐diphosphate (PRPP) synthase isozyme 4 was synthesized in Escherichia coli and purified to near homogeneity. The activity of the enzyme is independent of Pi; it is inhibited by ADP in a competitive manner, indicating a lack of an allosteric site; and it accepts ATP, dATP, GTP, CTP, and UTP as diphosphoryl donors. All of these properties are characteristic for class II PRPP synthases. Km values for ATP and ribose 5‐phosphate are 77 and 48 μM, respectively. Gel filtration reveals a molecular mass of the native enzyme of ∼110 kD, which is consistent with a homotrimer. Secondary structure prediction shows that spinach PRPP synthase isozyme 4 has a general folding similar to that of Bacillus subtilis class I PRPP synthase, for which the three‐dimensional structure has been solved, as the position and extent of helices and β‐sheets of the two enzymes are essentially conserved. Amino acid sequence comparison reveals that residues of class I PRPP synthases interacting with allosteric inhibitors are not conserved in class II PRPP synthases. Similarly, residues important for oligomerization of the B. subtilis enzyme show little conservation in the spinach enzyme. In contrast, residues of the active site of B. subtilis PRPP synthase show extensive conservation in spinach PRPP synthase isozyme 4.
Distance mapping of protein‐binding sites using spin‐labeled oligosaccharide ligands
Authors: Jain Nitin U. , Venot Andre , Umemoto Kimiko , Leffler Hakon , Prestegard James H. 
Published: July 2002

AbstractThe binding of a nitroxide spin‐labeled analog of N‐acetyllactosamine to galectin‐3, a mammalian lectin of 26 kD size, is studied to map the binding sites of this small oligosaccharide on the protein surface. Perturbation of intensities of cross‐peaks in the 15N heteronuclear single quantum coherence (HSQC) spectrum of full‐length galectin‐3 owing to the bound spin label is used qualitatively to idey protein residues proximate to the binding site for N‐acetyllactosamine. A protocol for converting intensity measurements to a more quantitative determination of distances between discrete protein amide protons and the bound spin label is then described. This protocol is discussed as part of a drug design strategy in which subsequent perturbation of chemical shifts of distance mapped amide cross‐peaks can be used effectively to screen a library of compounds for other ligands that bind to the target protein at distances suitable for chemical linkage to the primary ligand. This approach is novel in that it bypasses the need for structure determination and resonance assignment of the target protein.
Effects of i‐propanol on the structural dynamics of Thermomyces lanuginosa lipase revealed by tryptophan fluorescence
Authors: Zhu Keng , Jutila Arimatti , Tuominen Esa K.J. , Kinnunen Paavo K.J. 
Published: July 2002

AbstractInfluence of isopropanol (iPrOH) on the structural dynamics of Thermomyces lanuginosa lipase (TLL) was studied by steady‐state, time‐resolved, and stopped‐flow fluorescence spectroscopy, monitoring the intrinsic emission of Trp residues. The fluorescence of the four Trps of the wild‐type enzyme report on the global changes of the whole lipase molecule. To monitor the conformational changes in the so‐called “lid,” an α‐helical surface loop, the single Trp mutant W89m (W117F, W221H, W260H) was employed. Circular dichroism (CD) spectra revealed that iPrOH does not cause major alterations in the secondary structures of the wild‐type TLL and W89m. With increasing [iPrOH], judged by the ratio of emission intensities at 350 nm and 330 nm, the average microenvironment of the Trps in the wild‐type TLL became more hydrophobic, whereas Trp89 of W89m moved into a more hydrophilic microenvironment. Time‐resolved fluorescence measurements revealed no major changes to be induced by iPrOH neither in the shorter fluorescence lifetime component (τ1 = 0.5–1.2 ns) for the wild‐type TLL nor in the longer fluorescence lifetime component (τ2 = 4.8–6.0 ns) in the wild‐type TLL and the W89m mutant. Instead, for W89m on increasing iPrOH from 25% to 50% the value for τ1 increased significantly, from 0.43 to 1.5 ns. The shorter correlation time ϕ1 of W89m had a minimum of 0.08 ns in 25% iPrOH. Judged from the residual anisotropy r∞ the amplitude of the local motion of Trp89 increased upon increasing [iPrOH] 10%. Stopped‐flow fluorescence spectroscopy measurements suggested the lid to open within ≈2 ms upon transfer of W89m into 25% iPrOH. Steady‐state anisotropies and longer correlation times revealed increasing concentrations of iPrOH to result also in the formation of dimers as well as possibly also higher oligomers by TLL.