| completing the heterotrimer: isolation and characterization of an arabidopsis thaliana g protein gamma-subunit cdna. | heterotrimeric g proteins consist of three subunits (alpha, beta, and gamma). alpha- and beta- subunits have been previously cloned in plants, but the gamma-subunit has remained elusive. to isolate the gamma-subunit of a plant heterotrimeric g protein an arabidopsis thaliana yeast two-hybrid library was screened by using a tobacco g-beta-subunit as the bait protein. one positive clone (agg1) was isolated several times; it displays significant homology to the conserved domains of mammalian gamma- ... | 2000 | 11121078 |
| the cytosolic o-acetylserine(thiol)lyase gene is regulated by heavy metals and can function in cadmium tolerance. | regulation of the expression of the cytosolic o-acetylserine(thiol)lyase gene (atcys-3a) from arabidopsis thaliana under heavy metal stress conditions has been investigated. northern blot analysis of atcys-3a expression shows a 7-fold induction after 18 h of cadmium treatment. addition of 50 microm cdcl(2) to the irrigation medium of mature arabidopsis plants induces a rapid accumulation of the mrna throughout the leaf lamina, the root and stem cortex, and stem vascular tissues when compared wit ... | 2001 | 11121418 |
| atfim1 is an actin filament crosslinking protein from arabidopsis thaliana. | atfim1 is a widely expressed gene in arabidopsis thaliana that encodes a putative actin filament-crosslinking protein, atfim1, belonging to the fimbrin/plastin class of actin-binding proteins. in this report we have used bacterially expressed atfim1 and actin isolated from zea mays pollen to demonstrate that atfim1 functions as an actin filament-crosslinking protein. atfim1 binds pollen actin filaments (f-actin) in a calcium-independent manner, with an average dissociation constant (kd) of 0.55+ ... | 2000 | 11123801 |
| no way back: nitric oxide and programmed cell death in arabidopsis thaliana suspension cultures. | recent research has implicated nitric oxide (no) in the induction of the hypersensitive response (hr) during plant-pathogen interactions. here we demonstrate that arabidopsis suspension cultures generate elevated levels of no in response to challenge by avirulent bacteria, and, using no donors, show that these elevated levels of no are sufficient to induce cell death in arabidopsis cells independently of reactive oxygen species (ros). we also provide evidence that no-induced cell death is a form ... | 2000 | 11123805 |
| cytochrome p450 cyp79f1 from arabidopsis catalyzes the conversion of dihomomethionine and trihomomethionine to the corresponding aldoximes in the biosynthesis of aliphatic glucosinolates. | glucosinolates are natural plant products that have received rising attention due to their role in interactions between pests and crop plants and as chemical protectors against cancer. glucosinolates are derived from amino acids and have aldoximes as intermediates. we report that cytochrome p450 cyp79f1 catalyzes aldoxime formation in the biosynthesis of aliphatic glucosinolates in arabidopsis thaliana. using recombinant cyp79f1 functionally expressed in escherichia coli, we show that both dihom ... | 2001 | 11133994 |
| atsuc3, a gene encoding a new arabidopsis sucrose transporter, is expressed in cells adjacent to the vascular tissue and in a carpel cell layer. | the cdna corresponding to the open reading frame t17m13.3 from arabidopsis chromosome ii was isolated and the encoded protein was characterized as a member of a subgroup of higher plant sucrose transporters. the atsuc3 (arabidopsis thaliana sucrose transporter 3) open reading frame encodes a protein with 594 amino acid residues, being 81 and 82 residues longer than the previously described arabidopsis sucrose carriers atsuc1 and atsuc2. about 50 of these additional amino acids are part of an ext ... | 2000 | 11135120 |
| accumulation of soluble and wall-bound indolic metabolites in arabidopsis thaliana leaves infected with virulent or avirulent pseudomonas syringae pathovar tomato strains. | the chemical structures and accumulation kinetics of several major soluble as well as wall-bound, alkali-hydrolyzable compounds induced upon infection of arabidopsis thaliana leaves with pseudomonas syringae pathovar tomato were established. all identified accumulating products were structurally related to tryptophan. most prominent among the soluble substances were tryptophan, beta-d-glucopyranosyl indole-3-carboxylic acid, 6-hydroxyindole-3-carboxylic acid 6-o-beta-d-glucopyranoside, and the i ... | 2001 | 11136235 |
| deuterated delta 7-cholestenol analogues as mechanistic probes for wild-type and mutated delta 7-sterol-c5(6)-desaturase. | deuterium-labeled 5alpha-cholest-7-en-3beta-ol (1) bearing one or two deuteriums at the c-5alpha and (or) c-6alpha positions was synthesized in high isotopic and chiral purity. these compounds were used as substrates with the microsomal wild-type zea mays and recombinant arabidopsis thaliana delta(7)-sterol-c5(6)-desaturases (5-des) to probe directly the stereochemistry and the mechanism of the enzymatic reaction. clearly, in the conversion of 1 by both 5-dess, the 6alpha-hydrogen is removed. [6 ... | 2001 | 11141078 |
| competence of arabidopsis thaliana genotypes and mutants for agrobacterium tumefaciens-mediated gene transfer: role of phytohormones. | many plant species and/or genotypes are highly recalcitrant to agrobacterium-mediated genetic transformation, and yet little is known about this phenomenon. using several arabidopsis genotypes/ecotypes, the results of this study indicated that phytohormone pretreatment could overcome this recalcitrance by increasing the transformation rate in the known recalcitrant genotypes. transient expression of a t-dna encoded ss-glucuronidase (gus) gene and stable kanamycin resistance were obtained for the ... | 2000 | 11141170 |
| cloning and heterologous expression of a rape cdna encoding udp-glucose:sinapate glucosyltransferase. | a cdna encoding a udp-glucose:sinapate glucosyltransferase (sgt) that catalyzes the formation of 1-o-sinapoylglucose, was isolated from cdna libraries constructed from immature seeds and young seedlings of rape (brassica napus l.). the open reading frame encoded a protein of 497 amino acids with a calculated molecular mass of 55,970 da and an isoelectric point of 6.36. the enzyme, functionally expressed in escherichia coli, exhibited broad substrate specificity, glucosylating sinapate, cinnamate ... | 2000 | 11144274 |
| atspo11-1 is necessary for efficient meiotic recombination in plants. | the saccharomyces cerevisiae spo11 protein catalyses dna double-strand breaks (dsbs) that initiate meiotic recombination. the model plant arabidopsis thaliana possesses at least three spo11 homologues. t-dna and ethyl-methane sulfonate mutagenesis allowed us to show that meiotic progression is altered in plants in which the atspo11-1 gene is disrupted. both male and female meiocytes formed very few bivalents. furthermore, no fully synapsed chromosomes were observed during prophase i. later, in m ... | 2001 | 11157765 |
| two types of putative nuclear factors that physically interact with histidine-containing phosphotransfer (hpt) domains, signaling mediators in his-to-asp phosphorelay, in arabidopsis thaliana. | the higher plant, arabidopsis thaliana, has a large number of genes, each of which encodes a component of his-to-asp phosphorelay signal transduction systems. one type of such signal transducers are the histidine-containing phosphotransmitters (termed ahps), which presumably mediate his-to-asp phosphorelay. here we attempted to isolate a factor or factors that interact with ahp1, ahp2 and ahp3 by means of a yeast two-hybrid system. this allowed us to identify two types of nuclear-localizing prot ... | 2001 | 11158442 |
| plant orthologs of p300/cbp: conservation of a core domain in metazoan p300/cbp acetyltransferase-related proteins. | p300 and cbp participate as transcriptional coregulators in the execution of a wide spectrum of cellular gene expression programs controlling cell differentiation, growth and homeostasis. both proteins act together with sequence-specific transcription factors to modify chromatin structure of target genes via their intrinsic acetyltransferase activity directed towards core histones and some transcription factors. so far, p300-related proteins have been described in animals ranging from drosophila ... | 2001 | 11160878 |
| isolation of a ubiquitin-like (ubl5) gene from a screen identifying highly expressed and conserved iris genes. | we have screened a human adult iris cdna library to identify genes that are highly expressed and conserved between humans and pigs. we identified human iris cdnas that hybridized at high stringency to a porcine choroidal ring cdna probe. of 1568 human iris cdnas examined, 176 were found to have high expression in porcine choroidal rings. one of the 176 clones was identified as a previously uncharacterized cdna that we have named the ubiquitin-like 5 gene (ubl5). the ubl5 gene is located on chrom ... | 2001 | 11161819 |
| numerous and highly developed tubular projections from plastids observed in tobacco epidermal cells. | tubular projections from plastids (stromules) were observed using a stroma-targeted green fluorescent protein (gfp) fusion protein and a confocal laser scanning microscope. in tobacco (nicotiana tabacum) epidermal cells, stromules were observed at a high frequency. some of them were long and connected plastids. three days after particle bombardment, 80.6+/-6.99% of the transformed cells contained some plastids with more than one stromule, and 40.2+/-7.7% contained at least one pair of plastids c ... | 2001 | 11166431 |
| characterization of two plastid sigma factors, siga1 and siga2, that mainly function in matured chloroplasts in nicotiana tabacum. | we have isolated and characterized two genes from nicotiana tabacum, whose products function as putative sigma factors for plastid rna polymerase. since the amino acid sequence deduced from the dna sequences of both genes showed highly similar to that of the siga protein of arabidopsis thaliana, we termed the corresponding genes siga1 and siga2, respectively. transient expression assay using a green fluorescent protein (gfp) fusion construct indicated that the n-terminal region of the siga2 gene ... | 2000 | 11167008 |
| the cysteine synthase complex from plants. mitochondrial serine acetyltransferase from arabidopsis thaliana carries a bifunctional domain for catalysis and protein-protein interaction. | serine acetyltransferase (sat) catalyzes the rate-limiting step of cysteine biosynthesis in bacteria and plants and functions in association with o-acetylserine (thiol) lyase (oas-tl) in the cysteine synthase complex. very little is known about the structure and catalysis of sats except that they share a characteristic c-terminal hexapeptide-repeat domain with a number of enzymatically unrelated acyltransferases. computational modeling of this domain was performed for the mitochondrial sat isofo ... | 2001 | 11168407 |
| disruption of the arabidopsis rad50 gene leads to plant sterility and mms sensitivity. | the rad50 protein is involved in the cellular response to dna-double strand breaks (dsbs), including the detection of damage, activation of cell-cycle checkpoints, and dsb repair via recombination. it is essential for meiosis in yeast, is involved in telomere maintenance, and is essential for cellular viability in mice. here we present the isolation, sequence and characterization of the arabidopsis thaliana rad50 homologue (atrad50) and an arabidopsis mutant of this gene. a single copy of this g ... | 2001 | 11169180 |
| manipulation of salicylate content in arabidopsis thaliana by the expression of an engineered bacterial salicylate synthase. | salicylic acid (sa) plays a central role as a signalling molecule involved in plant defense against microbial attack. genetic manipulation of sa biosynthesis may therefore help to generate plants that are more disease-resistant. by fusing the two bacterial genes pcha and pchb from pseudomonas aeruginosa, which encode isochorismate synthase and isochorismate pyruvate-lyase, respectively, we have engineered a novel hybrid enzyme with salicylate synthase (sas) activity. the pchb-a fusion was expres ... | 2001 | 11169183 |
| heterologous complementation of yeast reveals a new putative function for chloroplast m-type thioredoxin. | in the chloroplast of higher plants, two types of thioredoxins (trx), namely trx m which shows high similarity to prokaryotic thioredoxins and trx f which is more closely related to eukaryotic thioredoxins, have been found and biochemically characterized, but little is known about their physiological specificity with respect to their target(s). here, we tested, in vivo, the ability of organelle-specific trx from arabidopsis thaliana to compensate for trx deficiency of a saccharomyces cerevisiae ... | 2001 | 11169189 |
| molecular aspects of beta-ketoacyl synthase (kas) catalysis. | crystal structure data for escherichia coli beta-ketoacyl synthase (kas) i with c(10) and c(12) fatty acid substrates bound in conjunction with results from mutagenizing residues in the active site leads to a model for catalysis. differences from and similarities to the other claisen enzymes carrying out decarboxylations reveal two catalytic mechanisms, one for kas i and kas ii, the other for kas iii and chalcone synthase. a comparison of the structures of kas i and kas ii does not reveal the ba ... | 2000 | 11171140 |
| further characterization of delta(8)-sphingolipid desaturases from higher plants. | a previously cloned cdna from helianthus annuus codes for a fusion protein composed of an n-terminal cytochrome b(5) and a c-terminal desaturase domain. for a functional identification, this cdna was expressed in saccharomyces cerevisiae and the structures of sphingolipid long-chain bases were analysed. the expression of this sunflower enzyme resulted in the formation of new delta(8)-trans/cis-phytosphingenine from c(18)- and c(20)-phytosphinganine present in wild-type yeast cells. to elucidate ... | 2000 | 11171153 |
| expression of the wax-specific condensing enzyme cut1 in arabidopsis. | the arabidopsis thaliana gene cut1 encodes a very-long-chain fatty acid-condensing enzyme required for the production of epicuticular wax in bolting stems. we have examined the expression pattern of cut1 in arabidopsis at different developmental stages and under different environmental conditions. rna blot analysis showed that cut1 was highly expressed in shoots, but not in roots. cut1 expression was detectable throughout development. light was required for cut1 expression, and expression was in ... | 2000 | 11171158 |
| the involvement of phospholipid:diacylglycerol acyltransferases in triacylglycerol production. | we have characterized three coa-independent types of enzyme, phospholipases, phospholipid:diacylglycerol acyltransferases (pdats) and cholinephosphotransferases, responsible for the removal of unusual fatty acids from phosphatidylcholine (pc) in microsomal preparations from developing oil seeds. the metabolism of sn-2-[(14)c]acyl-pc was monitored in microsomal preparations from various oilseeds having either medium-chain, acetylenic, epoxy or hydroxy fatty acids as their major fatty acids in the ... | 2000 | 11171177 |
| cloning and characterization of a cdna encoding serine palmitoyltransferase in arabidopsis thaliana. | the first and committed step in de novo sphingolipid synthesis is catalysed by serine palmitoyltransferase (ec 2.3.1.50), which condenses serine and palmitoyl-coa to form 3-ketosphinganine in a pyridoxal-5'-phosphate-dependent reaction. we have isolated and characterized a cdna clone from arabidopsis thaliana that is homologous to yeast and mammalian lcb2. for a functional identification, the a. thaliana homologous cdna was expressed in escherichia coli, which resulted in significant production ... | 2000 | 11171191 |
| characterization of sphingolipid long-chain base kinase in arabidopsis thaliana. | sphingolipid long-chain base (lcb) kinase catalyses the phosphorylation of sphingolipid lcb to form lcb 1-phosphate. based on sequence identity to a murine sphingosine kinase (murine sphk1a), we isolated and characterized a lcb kinase-like cdna in arabidopsis thaliana. the deduced amino acid sequence of the homologous cdna shows several regions that are highly conserved in lcb kinases from mouse, yeast, human and caenorhabditis elegans. these regions are not similar to those of other known kinas ... | 2000 | 11171192 |
| molecular characterization of fatty acid alpha-hydroperoxide-forming enzyme (alpha-oxygenase) in rice plants. | genes encoding an alpha-oxygenase, in nicotiana tabacum and arabidopsis thaliana, have been recently isolated. however, the reaction mechanism of the enzyme has not so far been elucidated. in this study, a cdna encoding the fatty acid alpha-oxygenase gene in rice plants was isolated. the deduced amino acid sequence showed high similarity (63.6%) to that of n. tabacum. the gene was cloned into an expression vector system, pqe-30, and expressed in escherichia coli as a host cell. palmitic acid as ... | 2000 | 11171200 |
| utility of the arabidopsis fae1 and yeast slc1-1 genes for improvements in erucic acid and oil content in rapeseed. | high-erucic acid (hea) brassica napus cultivars are regaining interest in industrial contexts. erucic acid and its derivatives are important renewable raw materials utilized in the manufacture of plastic films, in the synthesis of nylon 13,13, and in the lubricant and emollient industries. theoretically, the highest level of erucic acid that can be achieved by means of classical breeding is 66 mol%; however, using new approaches on the basis of genetic engineering, it might be possible to develo ... | 2000 | 11171262 |
| two families of acyl-coa thioesterases in arabidopsis. | we have identified two families of acyl-coa thioesterase (achs) in arabidopsis thaliana. one family, consisting of atach1 and atach2, appears to be peroxisomal, as they have type-1 peroxisomal targeting sequences. the other family, consisting of atach4 and atach5, resides in the endoplasmic reticulum, as shown by green fluorescent protein studies. atach2 has been overexpressed in escherichia coli and shows high levels of acyl-coa thioesterase activity against both 16:0-coa and 18:1-coa. atach5 h ... | 2000 | 11171266 |
| production of hydroxy fatty acids in the seeds of arabidopsis thaliana. | seed-specific expression in arabidopsis thaliana of oleate hydroxylase enzymes from castor bean and lesquerella fendleri resulted in the accumulation of hydroxy fatty acids in the seed oil. by using various arabidopsis mutant lines it was shown that the endoplasmic reticulum (er) n-3 desaturase (fad3) and the fae1 condensing enzyme are involved in the synthesis of polyunsaturated and very-long-chain hydroxy fatty acids, respectively. in arabidopsis plants with an active er delta12-oleate desatur ... | 2000 | 11171267 |
| characterization of an acyl-coa synthetase from arabidopsis thaliana. | one of the major goals of modern plant biotechnology is to manipulate lipid metabolism in oilseed crops to produce new and improved edible and industrial vegetable oils. lipids constitute the structural components of cellular membranes and act as sources of energy for the germinating seed and are therefore essential to plant cell function. both de novo synthesis and modification of existing lipids are dependent on the activity of acyl-coa synthetases (acss). to date, acss have been recalcitrant ... | 2000 | 11171270 |
| enhancement of seed oil content by expression of glycerol-3-phosphate acyltransferase genes. | arabidopsis thaliana was transformed with a plastidial safflower glycerol-3-phosphate acyltransferase (gpat) and an escherichia coli gpat. the genes were used directly and in modified forms with, as applicable, the plastidial targeting sequence removed, and with an endoplasmic reticulum targeting sequence added. seeds of plants transformed using only the vector were indistinguishable in oil content from wild-type control plants. all other gene constructs increased seed oil content. the unmodifie ... | 2000 | 11171271 |
| rad50 function is essential for telomere maintenance in arabidopsis. | we have identified and characterized an arabidopsis thaliana rad50 mutant plant containing a t-dna insertion in the atrad50 gene and showing both meiotic and dna repair defects. we report here that rad50/rad50 mutant cells show a progressive shortening of telomeric dna relative to heterozygous rad50/rad50 controls and that the mutant cell population rapidly enters a crisis, with the majority of the cells dying. surviving rad50 mutant cells have longer telomeres than wild-type cells, indicating t ... | 2001 | 11172016 |
| the cyp88a cytochrome p450, ent-kaurenoic acid oxidase, catalyzes three steps of the gibberellin biosynthesis pathway. | we have shown that ent-kaurenoic acid oxidase, a member of the cyp88a subfamily of cytochrome p450 enzymes, catalyzes the three steps of the gibberellin biosynthetic pathway from ent-kaurenoic acid to ga(12). a gibberellin-responsive barley mutant, grd5, accumulates ent-kaurenoic acid in developing grains. three independent grd5 mutants contain mutations in a gene encoding a member of the cyp88a subfamily of cytochrome p450 enzymes, defined by the maize dwarf3 protein. mutation of the dwarf3 gen ... | 2001 | 11172076 |
| higher plant cellulose synthases. | summary: cellulose, an aggregate of unbranched polymers of beta-1,4-linked glucose residues, is the major component of wood and thus paper, and is synthesized by plants, most algae, some bacteria and fungi, and even some animals. the genes that synthesize cellulose in higher plants differ greatly from the well-characterized genes found in acetobacter and agrobacterium sp. more correctly designated as 'cellulose synthase catalytic subunits', plant cellulose synthase (cesa) proteins are integral m ... | 2000 | 11178255 |
| an alternative cis-isoprenyltransferase activity in yeast that produces polyisoprenols with chain lengths similar to mammalian dolichols. | dolichyl monophosphate (dol-p) is a polyisoprenoid glycosyl carrier lipid essential for the assembly of a variety of glycoconjugates in the endoplasmic reticulum of eukaryotic cells. in yeast, dolichols with chain lengths of 14--17 isoprene units are predominant, whereas in mammalian cells they contain 19--22 isoprene units. in this biosynthetic pathway, t,t-farnesyl pyrophosphate is elongated to the appropriate long chain polyprenyl pyrophosphate by the sequential addition of cis-isoprene units ... | 2001 | 11181565 |
| the akt3 potassium channel protein interacts with the atpp2ca protein phosphatase 2c. | the akt3 potassium channel protein was identified as a strongly interacting partner of the arabidopsis thaliana protein phosphatase 2c (atpp2ca) in a yeast two-hybrid screen. a deletion analysis indicated that the catalytic domain of atpp2ca was essential for the interaction with akt3. furthermore, the related pp2c phosphatase abi1 did not interact with akt3 in yeast. | 2001 | 11181729 |
| plant biotechnology. italian scientists blast gmo restrictions. | while plant scientists around the world celebrate the complete sequence of the genome of the mustardlike plant arabidopsis thaliana (see p. 2054), embattled colleagues in italy are protesting new rules that bar all field trials involving genetically modified organisms (gmos). the researchers hope to turn the prevailing tide by bringing their plight to the attention of colleagues around the world and exerting pressure on their government through a petition drive. | 2000 | 11187815 |
| arabidopsis kin help keep genetics studies all in the family. | an unobtrusive weed often found at roadsides and other disturbed sites, arabidopsis thaliana has risen from its humble roots to become the model organism, or "lab rat," for studying plant molecular biology. now, by comparing the genetic makeup and characteristics of a. thaliana to its cousins, evolutionary biologists can discern how the plant has changed through time. | 2000 | 11187824 |
| [the complete genome sequence of arabidopsis thaliana]. | | 2001 | 11193333 |
| azorhizobium caulinodans ors571 colonizes the xylem of arabidopsis thaliana. | improved conditions were used for the aseptic growth of arabidopsis thaliana to investigate whether xylem colonization of a. thaliana by azorhizobium caulinodans ors571 might occur. when seedlings were inoculated with ors571 (pxlgd4) tagged with the lacz reporter gene, nearly all of the plants showed blue regions of ors571 colonization at lateral root cracks (lrc). the flavonoids naringenin and liquiritigenin significantly stimulated colonization of lrc by ors571. blue bands of ors571 (pxlgd4) b ... | 2001 | 11194878 |
| the role of hexokinase in plant sugar signal transduction and growth and development. | previous studies have revealed a central role of arabidopsis thaliana hexokinases (athxk1 and athxk2) in the glucose repression of photosynthetic genes and early seedling development. however, it remains unclear whether hxk can modulate the expression of diverse sugar-regulated genes. on the basis of the results of analyses of gene expression in hxk transgenic plants, we suggest that three distinct glucose signal transduction pathways exist in plants. the first is an athxk1-dependent pathway in ... | 2000 | 11197321 |
| increased abundance of mtd1 and mtd2 mrnas in nodules of decapitated medicago truncatula. | to gain insight into the molecular processes occurring in root nodule metabolism after stress, we used a mrna differential display (ddrt-pcr) approach to identify cdnas corresponding to genes whose expression is enhanced in nodules of decapitated medicago truncatula plants. two full-length cdnas of plant origin were isolated (mtd1 and mtd2). sequence analysis revealed that mtd1 is identical to an est clone (accession number aw559774) expressed in roots of m. truncatula upon infection with phytop ... | 2000 | 11197323 |
| single amino acid substitutions at the acyl-coa-binding domain interrupt 14[c]palmitoyl-coa binding of acbp2, an arabidopsis acyl-coa-binding protein with ankyrin repeats. | cytosolic acyl-coa-binding proteins (acbps) are small proteins (ca. 10 kda) that bind long-chain acyl-coas and are involved in the storage and intracellular transport of acyl-coas. previously, we have characterized an arabidopsis thaliana cdna encoding a novel membrane-associated acbp, designated acbp1, demonstrating the existence of a new form of acbp in plants (m.-l. chye, plant mol. biol. 38 (1998) 827-838). acbp1 likely participates in intermembrane lipid transport from the er to the plasma ... | 2000 | 11202434 |
| immunogold labeling of hrp pili of pseudomonas syringae pv. tomato assembled in minimal medium and in planta. | hypersensitive reaction and pathogenicity (hrp) genes are required for pseudomonas syringae pv. tomato (pst) dc3000 to cause disease in susceptible tomato and arabidopsis thaliana plants and to elicit the hypersensitive response in resistant plants. the hrp genes encode a type iii protein secretion system known as the hrp system, which in pst dc3000 secretes hrpa, hrpz, hrpw, and avrpto and assembles a surface appendage, named the hrp pilus, in hrp-gene-inducing minimal medium. hrpa has been sug ... | 2001 | 11204787 |
| thirty-plus functional families from a single motif. | it is now possible to identify over 30 functional subfamilies among the wd-repeat-containing proteins found in the completed genomes. the majority of these subfamilies have at least one member for which experimental data allow assignment to a cellular pathway or process. half of the 63 wd-repeat-containing proteins in saccharomyces cerevisiae, half of the 70 in caenorhabditis elegans, and a third of the 100 plus predicted in drosophila can be assigned to 23 of these functional subfamilies. perha ... | 2000 | 11206068 |
| plasticity to light cues and resources in arabidopsis thaliana: testing for adaptive value and costs. | plants shaded by neighbors or overhead foliage experience both a reduction in the ratio of red to far red light (r:fr), a specific cue perceived by phytochrome, and reduced photosynthetically active radiation (par), an essential resource. we tested the adaptive value of plasticity to crowding and to the cue and resource components of foliage shade in the annual plant arabidopsis thaliana by exposing 36 inbred families from four natural populations to four experimental treatments: (1) high densit ... | 2000 | 11209775 |
| utilization of mutants to analyze the interaction between arabidopsis thaliana and its naturally root-associated pseudomonas. | a model system based on the arabidopsis thaliana (l.) heynh. ws ecotype and its naturally colonizing pseudomonas thivervalensis rhizobacteria was defined. pseudomonas strains colonizing a. thaliana were found to modify the root architecture either in vivo or in vitro. a gnotobiotic system using bacteria labelled with green fluorescent protein revealed that p. thivervalensis exhibited a colonization profile similar to that of other rhizobacterial species. mutants of a. thaliana affected in root h ... | 2001 | 11216839 |
| the production of an inducible antisense alternative oxidase (aox1a) plant. | plant mitochondria contain an alternative oxidase (aox) acting as a terminal electron acceptor of the alternative pathway in the electron transport chain. here we describe the production of inducible antisense aox1a plants of arabidopsis thaliana (l.) heynh. and the procedures used to determine the resulting alternative pathway activity. the arabidopsis aox1a cdna sequence was cloned behind a copper-inducible promoter system in the antisense orientation. arabidopsis thaliana (columbia) plants we ... | 2001 | 11216842 |
| genesplicer: a new computational method for splice site prediction. | genesplicer is a new, flexible system for detecting splice sites in the genomic dna of various eukaryotes. the system has been tested successfully using dna from two reference organisms: the model plant arabidopsis thaliana and human. it was compared to six programs representing the leading splice site detectors for each of these species: netplantgene, netgene2, hspl, nnsplice, genio and spliceview. in each case genesplicer performed comparably to the best alternative, in terms of both accuracy ... | 2001 | 11222768 |
| one ring or two? determination of ring number in carotenoids by lycopene epsilon-cyclases. | carotenoids in the photosynthetic membranes of plants typically contain two beta-rings (e.g., beta-carotene and zeaxanthin) or one epsilon- and one beta-ring (e.g., lutein). carotenoids with two epsilon-rings are uncommon. we reported earlier that the arabidopsis thaliana lycopene epsilon-cyclase (lcye) adds one epsilon-ring to the symmetrical linear substrate lycopene, whereas the structurally related lycopene beta-cyclase (lcyb) adds two beta-rings. here we describe a cdna encoding lcye in rom ... | 2001 | 11226339 |
| mitochondrial 3-hydroxy-3-methylglutaryl-coa synthase deficiency: clinical course and description of causal mutations in two patients. | hereditary deficiency of mitochondrial hmg-coa synthase (mhs, omim 600234) is a poorly defined, treatable, probably underdiagnosed condition that can cause episodes of severe hypoketotic hypoglycemia. we present clinical follow-up and molecular analysis of the two known mhs-deficient patients. the diagnosis of mhs deficiency is challenging because the symptoms and metabolite pattern are not specific. moreover, enzyme analysis is technically difficult and requires sampling of an expressing organ ... | 2001 | 11228257 |
| the arabidopsis sensor his-kinase, ahk4, can respond to cytokinins. | his-to-asp (his-->asp) phosphorelay mechanisms are presumably involved in propagation of certain environmental stimuli, including phytohormones, in arabidopsis thaliana. in addition to the previously characterized his-kinases, namely, the etr1 family of ethylene receptors, cki1 cytokinin-sensor, and athk1 osomo-sensor, this higher plant has three more his-kinases (named ahk2, ahk3, and ahk4). by employing the well-known his-->asp phosphorelay systems in both the fission yeast and escherichia col ... | 2001 | 11230563 |
| novel family of sensor histidine kinase genes in arabidopsis thaliana. | we identified three novel, highly homologous, sensor histidine kinases that possibly function in the plasma membrane of arabidopsis thaliana, i.e. ahk2, 3 and 4. while ahk2 and 3 are expressed in several organs, ahk4 is mainly expressed in roots. ahk3 suppresses a sensor histidine kinase mutant of yeast. | 2001 | 11230578 |
| arabidopsis genome: life without notch. | the complete genome sequence of the flowering plant arabidopsis thaliana has been determined. new insights have come from comparisons between this sequence and genome sequences of other species, including those of cyanobacteria, yeast, worms and flies. | 2001 | 11231172 |
| [differential accumulation of the new high-affinity phosphate transporter candidated gene fragment in rice roots in response to phosphorus deficiency stress]. | phosphate is a major constraint to crop production, and phosphate uptake in plant is mainly by high-affinity phosphate transporter under phosphate deficiency condition. using rt-pcr, a 1,178 bp phosphate transporter gene fragment ojpt1 was cloned from roots of jingxi17 (oryza sativa l. ssp. japanica) supplied with no phosphate. the comparison of this sequence with ones in genbank indicated that it shared about 70% similarity at amino acid level with other phosphate transporters in higher plants, ... | 2001 | 11233258 |
| open-reading-frame sequence tags (osts) support the existence of at least 17,300 genes in c. elegans. | the genome sequences of caenorhabditis elegans, drosophila melanogaster and arabidopsis thaliana have been predicted to contain 19,000, 13,600 and 25,500 genes, respectively. before this information can be fully used for evolutionary and functional studies, several issues need to be addressed. first, the gene number estimates obtained in silico and not yet supported by any experimental data need to be verified. for example, it seems biologically paradoxical that c. elegans would have 50% more ge ... | 2001 | 11242119 |
| gene structure for adenosine kinase in chinese hamster and human: high-frequency mutants of cho cells involve deletions of several introns and exons. | the structure for the adenosine kinase (ak) gene has been determined from chinese hamster (ch) and human cells. the ak gene in ch is comprised of 11 exons ranging in length from 36 to 765 nt, with the majority <100 nt. the exact lengths of the intervening introns have not been determined, but most of them are indicated to be very large (>15 kb). a 6.6-kb fragment from human cells was also sequenced, and it contained only a single exon corresponding to exon 10 in ch. the blast searches of the sub ... | 2001 | 11242543 |
| molecular cloning and expression in yeast of 2,3-oxidosqualene-triterpenoid cyclases from arabidopsis thaliana. | a vast array of triterpenes are found in living organisms in addition to lanosterol and cycloartenol, which are involved in sterol biosynthesis in non-photosynthetic and photosynthetic eukaryotes respectively. the chemical structure of these triterpenes is determined by a single step catalysed by 2,3-oxidosqualene-triterpene cyclases. the present study describes cloning and functional expression in yeast of several os-triterpene cyclases. three arabidopsis thaliana cdnas encoding proteins (atlup ... | 2001 | 11247608 |
| genomic organization and transcriptional analysis of stdeficiens in solanum tuberosum l. | the genomic organization of stdeficiens (stdef), the potato orthologous gene to deficiens (def) from antirrhinum majus and apetala3 (ap3) from arabidopsis thaliana, has been investigated. southern-blot analysis on genomic dna from dihaploid potato lines, using 5'-gene specific probes, revealed polymorphisms that were consistent with the existence in potato of at least two copies of stdef per haploid genome. this was confirmed by the detection of at least six different stdef transcripts in the co ... | 2001 | 11250071 |
| characterization and expression of the genes for cytochrome c oxidase subunit vib (cox6b) from rice and arabidopsis thaliana. | many of the subunits of cytochrome c oxidase (cox) in the mitochondria of higher plants are encoded by nuclear genes. these genes are less characterized compared to mitochondrial-encoded genes. we previously isolated a cdna encoding cox6b (designated oscox6b1 in this study) from the rice nuclear genome and analyzed its expression. the deduced protein had an extended n-terminus compared with human and yeast cox6b proteins. in this study, we identified another cox6b gene (oscox6b2) in rice and rev ... | 2001 | 11250078 |
| disruption of individual members of arabidopsis syntaxin gene families indicates each has essential functions. | syntaxins are a large group of proteins found in all eukaryotes involved in the fusion of transport vesicles to target membranes. twenty-four syntaxins grouped into 10 gene families are found in the model plant arabidopsis thaliana, each group containing one to five paralogous members. the arabidopsis syp2 and syp4 gene families contain three members each that share 60 to 80% protein sequence identity. gene disruptions of the yeast (saccharomyces cerevisiae) orthologs of the syp2 and syp4 gene f ... | 2001 | 11251103 |
| one rna polymerase serving two genomes. | the land plant arabidopsis thaliana contains three closely related nuclear genes encoding phage-type rna polymerases (rpot;1, rpot;2 and rpot;3). the gene products of rpot;1 and rpot;3 have previously been shown to be imported into mitochondria and chloroplasts, respectively. here we show that the transit peptide of rpot;2 possesses dual targeting properties. transient expression assays in tobacco protoplasts as well as stable transformation of arabidopsis plants demonstrate efficient targeting ... | 2000 | 11258484 |
| an arabidopsis circadian clock component interacts with both cry1 and phyb. | most organisms, from cyanobacteria to mammals, use circadian clocks to coordinate their activities with the natural 24-h light/dark cycle. the clock proteins of drosophila and mammals exhibit striking homology but do not show similarity with clock proteins found so far from either cyanobacteria or neurospora. each of these organisms uses a transcriptionally regulated negative feedback loop in which the messenger rna levels of the clock components cycle over a 24-h period. proteins containing pas ... | 2001 | 11260718 |
| regulation of vegetative phase change in arabidopsis thaliana by cyclophilin 40. | during its development, a plant shoot progresses from a juvenile to an adult phase of vegetative growth and from a reproductively incompetent to a reproductively competent state. in arabidopsis, loss-of-function mutations in squint (sqn) reduced the number of juvenile leaves and had subtle effects on inflorescence morphology but had no effect on flowering time or on reproductive competence. sqn encodes the arabidopsis homolog of cyclophilin 40 (cyp40), a protein found in association with the hsp ... | 2001 | 11264535 |
| identification of 10 novel snorna gene clusters from arabidopsis thaliana. | ten novel small nucleolar rna (snorna) gene clusters, consisting of two or three snorna genes, respectively, were identified from arabidopsis thaliana. twelve of the 25 snorna genes in these clusters are homologous to those of yeast and mammals according to the conserved antisense sequences that guide 2'-o-ribose methylation of rrna. the remaining 13 snorna genes, including two 5.8s rrna methylation guides, are new genes identified from a.thaliana. interestingly, seven methylated nucleotides, pr ... | 2001 | 11266566 |
| mapping the virus and host genes involved in the resistance response in cucumber mosaic virus-infected arabidopsis thaliana. | a yellow strain of cucumber mosaic virus (cmv) [cmv(y)] induces a resistance response characterized by inhibition of virus systemic movement with development of necrotic local lesions in the virus-inoculated leaves of arabidopsis thaliana ecotype c24. in this report, the avirulence determinant in the virus genome was defined and the resistance gene (rcy1) of c24 was genetically mapped. the response of c24 to cmv containing the chimeric rna3 between cmv(y) and a virulent strain of cmv indicated t ... | 2001 | 11266586 |
| alternative forms of formamidopyrimidine-dna glycosylase from arabidopsis thaliana. | formamidopyrimidine-dna glycosylase (fpg) catalyzes the initial steps in the repair of dna containing oxidized purines. two complementary dna clones encoding homologs of bacterial fpg, designated atfpg-1 and atfpg-2, have been isolated from arabidopsis thaliana. they are products of alternative splicing of the transcript of a single gene. proteins encoded by both clones, atfpg-1 and atfpg-2, engineered to contain oligohistidine sequences on their c-terminal ends, were expressed in escherichia co ... | 2001 | 11272725 |
| vipp1, a nuclear gene of arabidopsis thaliana essential for thylakoid membrane formation. | the conversion of light to chemical energy by the process of photosynthesis is localized to the thylakoid membrane network in plant chloroplasts. although several pathways have been described that target proteins into and across the thylakoids, little is known about the origin of this membrane system or how the lipid backbone of the thylakoids is transported and fused with the target membrane. thylakoid biogenesis and maintenance seem to involve the flow of membrane elements via vesicular transp ... | 2001 | 11274447 |
| vipp1 deletion mutant of synechocystis: a connection between bacterial phage shock and thylakoid biogenesis? | plant chloroplasts originated from an endosymbiotic event by which an ancestor of contemporary cyanobacteria was engulfed by an early eukaryotic cell and then transformed into an organelle. oxygenic photosynthesis is the specific feature of cyanobacteria and chloroplasts, and the photosynthetic machinery resides in an internal membrane system, the thylakoids. the origin and genesis of thylakoid membranes, which are essential for oxygenic photosynthesis, are still an enigma. vipp1 (vesicle-induci ... | 2001 | 11274448 |
| expression studies on aux1-like genes in medicago truncatula suggest that auxin is required at two steps in early nodule development. | medicago truncatula contains a family of at least five genes related to aux1 of arabidopsis thaliana (termed mtlax genes for medicago truncatula-like aux1 genes). the high sequence similarity between the encoded proteins and aux1 implies that the mtlax genes encode auxin import carriers. the mtlax genes are expressed in roots and other organs, suggesting that they play pleiotropic roles related to auxin uptake. in primary roots, the mtlax genes are expressed preferentially in the root tips, part ... | 2001 | 11277424 |
| immunocytochemical localization of hrpa and hrpz supports a role for the hrp pilus in the transfer of effector proteins from pseudomonas syringae pv. tomato across the host plant cell wall. | the hrp pilus, composed of hrpa subunits, is an essential component of the type iii secretion system in pseudomonas syringae. we used electron microscopy (em) and immunocytochemistry to examine production of the pilus in vitro from p. syringae pv. tomato strain dc3000 grown under hrp-inducing conditions on em grids. pili, when labeled with antibodies to hrpa, developed rapidly in a nonpolar manner shortly after the detection of the hrpa transcript and extended up to 5 microm into surrounding med ... | 2001 | 11277437 |
| lipid phosphate phosphatases in arabidopsis. regulation of the atlpp1 gene in response to stress. | an arabidopsis thaliana gene (atlpp1) was isolated on the basis that it was transiently induced by ionizing radiation. the putative atlpp1 gene product showed homology to the yeast and mammalian lipid phosphate phosphatase enzymes and possessed a phosphatase signature sequence motif. heterologous expression and biochemical characterization of the atlpp1 gene in yeast showed that it encoded an enzyme (atlpp1p) that exhibited both diacylglycerol pyrophosphate phosphatase and phosphatidate phosphat ... | 2001 | 11278556 |
| uncoupling of 3'-phosphatase and 5'-kinase functions in budding yeast. characterization of saccharomyces cerevisiae dna 3'-phosphatase (tpp1). | polynucleotide kinase is a bifunctional enzyme containing both dna 3'-phosphatase and 5'-kinase activities seemingly suited to the coupled repair of single-strand nicks in which the phosphate has remained with the 3'-base. we show that the yeast saccharomyces cerevisiae is able to repair transformed dephosphorylated linear plasmids by non-homologous end joining with considerable efficiency independently of the end-processing polymerase pol4p. homology searches and biochemical assays did not reve ... | 2001 | 11278831 |
| overlapping destinations for two dual targeted glycyl-trna synthetases in arabidopsis thaliana and phaseolus vulgaris. | in plant mitochondria, some of the trnas are encoded by the mitochondrial genome and resemble their prokaryotic counterparts, whereas the remaining trnas are encoded by the nuclear genome and imported from the cytosol. generally, mitochondrial isoacceptor trnas all have the same genetic origin. one known exception to this rule is the group of trna(gly) isoacceptors in dicotyledonous plants. a mitochondrion-encoded trna(gly) and at least one nucleus-encoded trna(gly) coexist in the mitochondria o ... | 2001 | 11278923 |
| genome-scale compositional comparisons in eukaryotes. | we examined dinucleotide relative abundances and their biases in recent sequences of eukaryotic genomes and chromosomes, including human chromosomes 21 and 22, saccharomyces cerevisiae, arabidopsis thaliana, and drosophila melanogaster. we found that dinucleotide relative abundances are remarkably constant across human chromosomes and within the dna of a particular species. the dinucleotide biases differ between species, providing a genome signature that is characteristic of the bulk properties ... | 2001 | 11282969 |
| ftsz ring formation at the chloroplast division site in plants. | among the events that accompanied the evolution of chloroplasts from their endosymbiotic ancestors was the host cell recruitment of the prokaryotic cell division protein ftsz to function in chloroplast division. ftsz, a structural homologue of tubulin, mediates cell division in bacteria by assembling into a ring at the midcell division site. in higher plants, two nuclear-encoded forms of ftsz, ftsz1 and ftsz2, play essential and functionally distinct roles in chloroplast division, but whether th ... | 2001 | 11285278 |
| x-ray structure of the human hyperplastic discs protein: an ortholog of the c-terminal domain of poly(a)-binding protein. | the poly(a)-binding protein (pabp) recognizes the 3' mrna poly(a) tail and plays an essential role in eukaryotic translation initiation and mrna stabilization/degradation. pabp is a modular protein, with four n-terminal rna-binding domains and an extensive c terminus. the c-terminal region of pabp is essential for normal growth in yeast and has been implicated in mediating pabp homo-oligomerization and protein-protein interactions. a small, proteolytically stable, highly conserved domain has bee ... | 2001 | 11287654 |
| jasmonic acid carboxyl methyltransferase: a key enzyme for jasmonate-regulated plant responses. | methyl jasmonate is a plant volatile that acts as an important cellular regulator mediating diverse developmental processes and defense responses. we have cloned the novel gene jmt encoding an s-adenosyl-l-methionine:jasmonic acid carboxyl methyltransferase (jmt) from arabidopsis thaliana. recombinant jmt protein expressed in escherichia coli catalyzed the formation of methyl jasmonate from jasmonic acid with k(m) value of 38.5 microm. jmt rna was not detected in young seedlings but was detected ... | 2001 | 11287667 |
| characterization of a novel class of plant homeodomain proteins that bind to the c4 phosphoenolpyruvate carboxylase gene of flaveria trinervia. | we are interested in the regulatory mechanisms responsible for the mesophyll-specific expression of c4 phosphoenolpyruvate carboxylase (pepcase). a one-hybrid screen resulted in the cloning of four different members of a novel class of plant homeodomain proteins, which are most likely involved in the mesophyll-specific expression of the c4 pepcase gene in c4 species of the genus flaveria. inspection of the homeodomains of the four proteins reveals that they share many common features with homeod ... | 2001 | 11289511 |
| cortical actin filaments in guard cells respond differently to abscisic acid in wild-type and abi1-1 mutant arabidopsis. | cortical actin filaments in guard cells of commelina communis l. show signal-specific organization during stomatal movements [s.-o. eun and y. lee (1997) plant physiol 115: 1491-1498; s.-o. eun and y. lee (2000) planta 210: 1014-1017]. to study the roles of actin in signal transduction, it is advantageous to use arabidopsis thaliana (l.) heynh., an excellent model plant with numerous well-characterized mutants. using an immunolocalization technique, we found that actin deployments in guard cells ... | 2001 | 11289613 |
| a millennial myosin census. | the past decade has seen a remarkable explosion in our knowledge of the size and diversity of the myosin superfamily. since these actin-based motors are candidates to provide the molecular basis for many cellular movements, it is essential that motility researchers be aware of the complete set of myosins in a given organism. the availability of cdna and/or draft genomic sequences from humans, drosophila melanogaster, caenorhabditis elegans, arabidopsis thaliana, saccharomyces cerevisiae, schizos ... | 2001 | 11294886 |
| an arabidopsis thaliana protein interacts with a movement protein of turnip crinkle virus in yeast cells and in vitro. | plant virus movement proteins bind host components to promote virus movement from initially infected cells to neighbouring cells. in this study, cdna clones encoding p8 and p9, two small proteins required for the movement of turnip crinkle virus, were used as 'bait' in a yeast two-hybrid system to screen an arabidopsis thaliana cdna library for interactive proteins. one a. thaliana clone was identified that encodes a protein, designated atp8, which interacted with p8 in yeast cells and in vitro. ... | 2001 | 11297700 |
| a putative proton binding site of plasma membrane h(+)-atpase identified through homology modelling. | we have used the 2.6 a structure of the rabbit sarcoplasmic reticulum ca(2+)-atpase isoform 1a, serca1a [toyoshima, c., nakasako, m., nomura, h. and ogawa, h. (2000) nature 405, 647-655], to build models by homology modelling of two plasma membrane (pm) h(+)-atpases, arabidopsis thaliana aha2 and saccharomyces cerevisiae pma1. we propose that in both yeast and plant pm h(+)-atpases a strictly conserved aspartate in transmembrane segment (m)6 (d684(aha2)/d730(pma1)), and three backbone carbonyls ... | 2001 | 11297724 |
| functional characterization of sphingolipid c4-hydroxylase genes from arabidopsis thaliana. | in the genome of arabidopsis thaliana, two genes were identified encoding isoenzymes for c4-hydroxylation of long chain bases (lcb) in plant sphingolipids. both predicted proteins consist of 258 amino acid residues (77% identity) which show sequence similarity to di-iron-binding enzymes, such as sur2p and erg3p from yeast, involved in oxygen-dependent lipid modifications. heterologous expression of these genes in a yeast sur2delta-null mutant lacking c4-lcb hydroxylation resulted in the formatio ... | 2001 | 11297741 |
| primary structure and sexual stage-specific expression of a lammer protein kinase of plasmodium falciparum. | we have isolated a lammer-like gene from plasmodium falciparum by vectorette technique. the gene consists of 3316 bp encoding a protein 881 amino acids with a predicted molecular mass of approximately 106.7 kda. the encoded protein, termed pflammer, is composed of two distinct domains. the n-terminal domain is not related to any previously described protein kinases and has several interesting features including multiple consensus phosphorylation sites for a range of protein kinases, a number of ... | 2001 | 11306117 |
| homologous recombination in planta is stimulated in the absence of rad50. | chromosomal double-strand dna breaks must be repaired; in the absence of repair the resulting acentromeric (and telomereless) fragments may be lost and/or the broken dna ends may recombine causing general chromosomal instability. the rad50/mre11/xrs2 protein complex acts at dna ends and is implicated in both homologous and non-homologous recombination. we have isolated a rad50 mutant of the plant arabidopsis thaliana and show here that it has a somatic hyper-recombination phenotype in planta. th ... | 2001 | 11306548 |
| peroxisomal alanine : glyoxylate aminotransferase (agt1) is a photorespiratory enzyme with multiple substrates in arabidopsis thaliana. | at least two glyoxylate aminotransferases are hypothesized to participate in the steps of photorespiration located in peroxisomes. until recently, however, genes encoding these enzymes had not been identified. we describe the isolation and characterization of an alanine : glyoxylate aminotransferase (agt1, formerly agt) cdna from arabidopsis thaliana. southern blot analysis confirmed that arabidopsis agt1 is encoded by a single gene. homologs of this class iv aminotransferase are also known in o ... | 2001 | 11309139 |
| effects of urate, a natural inhibitor of peroxynitrite-mediated toxicity, in the response of arabidopsis thaliana to the bacterial pathogen pseudomonas syringae. | urate, a natural peroxynitrite scavenger, has been used to investigate the possible role of peroxynitrite during plant-pathogen interactions. urate greatly reduced lesion formation in arabidopsis leaves treated with an abiotic peroxynitrite-generating system or with a peroxynitrite solution, indicating that it can act as an effective scavenger in planta. in the interaction with the avirulent pseudomonas syringae pv. phaseolicola (avrrpm1+), cell death in the inoculated area was strongly reduced ... | 2001 | 11309143 |
| a recessive mutation in the arabidopsis ssi2 gene confers sa- and npr1-independent expression of pr genes and resistance against bacterial and oomycete pathogens. | the arabidopsis thaliana npr1 gene is required for salicylic acid (sa)-induced expression of pathogenesis-related (pr) genes and systemic acquired resistance. however, loss-of-function mutations in npr1 do not confer complete loss of pr gene expression or disease resistance. thus these responses also can be activated via an npr1-independent pathway that currently remain to be elucidated. the ssi2-1 mutant, identified in a genetic screen for suppressors of npr1-5, affects signaling through the np ... | 2001 | 11309146 |
| abnormal callose response phenotype and hypersusceptibility to peronospoara parasitica in defence-compromised arabidopsis nim1-1 and salicylate hydroxylase-expressing plants. | to investigate the impact of induced host defenses on the virulence of a compatible peronospora parasitica strain on arabidopsis thaliana, we examined growth and development of this pathogen in nim1-1 mutants and transgenic salicylate hydroxylase plants. these plants are unable to respond to or accumulate salicylic acid (sa), respectively, are defective in expression of systemic acquired resistance (sar), and permit partial growth of some normally avirulent pathogens. we dissected the p. parasit ... | 2001 | 11310731 |
| ten isoenzymes of xyloglucan endotransglycosylase from plant cell walls select and cleave the donor substrate stochastically. | to map the preferred cleavage sites of xyloglucan endotransglycosylases (xets; ec 2.4.1.207) along the donor substrate chain, we incubated the enzymes with tamarind (tamarindus indica) xyloglucan (donor substrate; approximately 205 kda; 21 microm) plus the nonasaccharide [(3)h]xllgol (gal(2).xyl(3).glc(3). [(3)h]glucitol; acceptor substrate; 0.6 microm). after short incubation times, to minimize multiple cleavages, the size of the (3)h-labelled transglycosylation products (determined by gel-perm ... | 2001 | 11311129 |
| identification of genes encoding adenylate isopentenyltransferase, a cytokinin biosynthesis enzyme, in arabidopsis thaliana. | the initial step in the de novo biosynthesis of cytokinin in higher plants is the formation of isopentenyladenosine 5'-monophosphate (ipmp) from amp and dimethylallylpyrophosphate (dmapp), which is catalyzed by adenylate isopentenyltransferase (ipt). although cytokinin is an essential hormone for growth and development, the nature of the enzyme for its biosynthesis in higher plants has not been identified. herein, we describe the molecular cloning and biochemical identification of ipts from arab ... | 2001 | 11313355 |
| a translationally regulated tousled kinase phosphorylates histone h3 and confers radioresistance when overexpressed. | the gene tousled of arabidopsis thaliana encodes a protein kinase which, when mutated, results in abnormal flower development. from a library of mrnas that are translationally upregulated by overexpression of the translation initiation factor 4e, we identified a mammalian tousled like kinase (tlk1b). the human tlk1b mrna contains a 5'utr 1088-nt-long with two upstream aug codons, and was found to be very inhibitory for translation. the tlk1b protein localizes almost exclusively to the nuclei. tl ... | 2001 | 11314006 |
| characterization of a novel carotenoid cleavage dioxygenase from plants. | the plant hormone abscisic acid is derived from the oxidative cleavage of a carotenoid precursor. enzymes that catalyze this carotenoid cleavage reaction, nine-cis epoxy-carotenoid dioxygenases, have been identified in several plant species. similar proteins, whose functions are not yet known, are present in diverse organisms. a putative cleavage enzyme from arabidopsis thaliana contains several highly conserved motifs found in other carotenoid cleavage enzymes. however, the overall homology wit ... | 2001 | 11316814 |
| cks1at overexpression in arabidopsis thaliana inhibits growth by reducing meristem size and inhibiting cell-cycle progression. | the suc1/cks1 proteins associate with cyclin-dependent kinases (cdks) and play an essential role in the regulation of the cell cycle. recently, an arabidopsis thaliana suc1/cks1 homologous gene, designated cks1at, has been cloned. here, overexpression of cks1at in arabidopsis is shown to reduce leaf size and root growth rates. reduced root growth resulted primarily from an increase of the cell-cycle duration and a shortening of the meristem. endoreduplication was unaffected. the increased cell-c ... | 2001 | 11319029 |
| extracellular secretion of aspergillus phytase from arabidopsis roots enables plants to obtain phosphorus from phytate. | phosphorus (p) deficiency in soil is a major constraint for agricultural production worldwide. despite this, most soils contain significant amounts of total soil p that occurs in inorganic and organic fractions and accumulates with phosphorus fertilization. a major component of soil organic phosphorus occurs as phytate. we show that when grown in agar under sterile conditions, arabidopsis thaliana plants are able to obtain phosphorus from a range of organic phosphorus substrates that would be ex ... | 2001 | 11319031 |
| selective interaction of triazole derivatives with dwf4, a cytochrome p450 monooxygenase of the brassinosteroid biosynthetic pathway, correlates with brassinosteroid deficiency in planta. | brassinazole, a synthetic chemical developed in our laboratory, is a triazole-type brassinosteroid biosynthesis inhibitor that induces dwarfism in various plant species. the target sites of brassinazole were investigated by chemical analyses of endogenous brassinosteroids (brs) in brassinazole-treated catharanthus roseus cells. the levels of castasterone and brassinolide in brassinazole-treated plant cells were less than 6% of the levels in untreated cells. in contrast, campestanol and 6-oxocamp ... | 2001 | 11319239 |
| noncompetitive inhibition of plant protein ser/thr phosphatase pp7 by phosphate. | changes in the cytoplasmic inorganic phosphate (p(i)) concentrations are an important cue for the plant cells to regulate their metabolism and phosphate homeostasis. however, phosphate sensors/receptors involved in this regulation are largely unknown. p(i) is a common nonspecific competitive inhibitor of phosphatases, usually in millimolar range. here we report a procedure to refold recombinant arabidopsis thaliana protein ser/thr phosphatase pp7 and demonstrate that pp7 is inhibited by submilli ... | 2001 | 11322772 |
| identification and characterization of the gene encoding the mitochondrial elongation factor g in rice. | a plant nuclear gene coding for a mitochondrial elongation factor g (mef-g) was cloned from a cdna library and genomic library of rice (oryza sativa l.). this dna sequence predicts a 757-amino-acid protein exhibiting 79%, 55% and 49% homology to arabidopsis thaliana, saccharomyces cerevisiae and rat mef-g respectively, 53% homology to the elongation factor g in escherichia coli and 43% homology to soybean chloroplast elongation factor g. the deduced amino acid sequence contains the characteristi ... | 2000 | 11328648 |