Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| identification of legionella pneumophila genes important for infection of amoebas by signature-tagged mutagenesis. | legionella pneumophila is a facultative intracellular gram-negative rod that causes pneumonia in humans. free-living amoebas are thought to serve as a reservoir for legionella infections. signature-tagged mutagenesis was employed to identify legionella pneumophila genes necessary for survival in the amoeba acanthamoeba castellanii. six mutant strains were defective in assays of invasion and intracellular growth. four mutants also exhibited invasion and replication defects in hartmannella vermifo ... | 2001 | 11159993 |
| control of hema expression in rhodobacter sphaeroides 2.4.1: effect of a transposon insertion in the hbda gene. | the common precursor to all tetrapyrroles is 5-aminolevulinic acid (ala), and in rhodobacter sphaeroides its formation occurs via the shemin pathway. ala synthase activity is encoded by two differentially regulated genes in r. sphaeroides 2.4.1: hema and hemt. in our investigations of hema regulation, we applied transposon mutagenesis under aerobic conditions, followed by a selection that identified transposon insertion mutants in which hema expression is elevated. one of these mutants has been ... | 2001 | 11160087 |
| molecular interactions between the specialist herbivore manduca sexta (lepidoptera, sphingidae) and its natural host nicotiana attenuata. i. large-scale changes in the accumulation of growth- and defense-related plant mrnas. | plants respond to herbivore attack with a dramatic functional reorganization that involves the activation of direct and indirect defenses and tolerance, which in turn make large demands on primary metabolism. here we provide the first characterization of the transcriptional reorganization that occurs after insect attack in a model plant-herbivore system: nicotiana attenuata torr. ex wats.-manduca sexta. we used mrna differential display to characterize one-twentieth of the insect-responsive tran ... | 2001 | 11161026 |
| genetic snapshots of the rhizobium species ngr234 genome. | in nitrate-poor soils, many leguminous plants form nitrogen-fixing symbioses with members of the bacterial family rhizobiaceae. we selected rhizobium sp. ngr234 for its exceptionally broad host range, which includes more than i 12 genera of legumes. unlike the genome of bradyrhizobium japonicum, which is composed of a single 8.7 mb chromosome, that of ngr234 is partitioned into three replicons: a chromosome of about 3.5 mb, a megaplasmid of more than 2 mb (pngr234b) and pngr234a, a 536,165 bp pl ... | 2000 | 11178268 |
| enhanced symbiotic performance by rhizobium tropici glycogen synthase mutants. | we isolated a tn5-induced rhizobium tropici mutant that has enhanced capacity to oxidize n,n-dimethyl-p-phenylendiamine (dmpd) and therefore has enhanced respiration via cytochrome oxidase. the mutant had increased levels of the cytochromes c(1) and cycm and a small increase in the amount of cytochrome aa(3). in plant tests, the mutant increased the dry weight of phaseolus vulgaris plants by 20 to 38% compared with the control strain, thus showing significantly enhanced symbiotic performance. th ... | 2001 | 11208782 |
| connection between poly-beta-hydroxybutyrate biosynthesis and growth on c(1) and c(2) compounds in the methylotroph methylobacterium extorquens am1. | several dna regions containing genes involved in poly-beta-hydroxybutyrate (phb) biosynthesis and degradation and also in fatty acid degradation were identified from genomic sequence data and have been characterized in the serine cycle facultative methylotroph methylobacterium extorquens am1. genes involved in phb biosynthesis include those encoding beta-ketothiolase (phaa), nadph-linked acetoacetyl coenzyme a (acetyl-coa) reductase (phab), and phb synthase (phac). phaa and phab are closely link ... | 2001 | 11208803 |
| phylogenetic and dna-dna hybridization analyses of bradyrhizobium species. | the 16s rdna sequence of bradyrhizobium liaoningense was determined and analysed together with sequences of other bradyrhizobium species and related taxa. in addition, dna-dna hybridizations were performed between representative strains of the three bradyrhizobium species. bradyrhizobium liaoningense is genotypically highly related to bradyrhizobium japonicum, whereas bradyrhizobium elkanii is more distantly related to these two species. the fact that afipia, agromonas, blastobacter, nitrobacter ... | 2001 | 11211247 |
| genomic and genetic dissection of an archaeal regulon. | the extremely halophilic archaeon halobacterium sp. nrc-1 can grow phototrophically by means of light-driven proton pumping by bacteriorhodopsin in the purple membrane. here, we show by genetic analysis of the wild type, and insertion and double-frame shift mutants of bat that this transcriptional regulator coordinates synthesis of a structural protein and a chromophore for purple membrane biogenesis in response to both light and oxygen. analysis of the complete halobacterium sp. nrc-1 genome se ... | 2001 | 11226271 |
| p(ii) signal transduction proteins, pivotal players in microbial nitrogen control. | the p(ii) family of signal transduction proteins are among the most widely distributed signal proteins in the bacterial world. first identified in 1969 as a component of the glutamine synthetase regulatory apparatus, p(ii) proteins have since been recognized as playing a pivotal role in control of prokaryotic nitrogen metabolism. more recently, members of the family have been found in higher plants, where they also potentially play a role in nitrogen control. the p(ii) proteins can function in t ... | 2001 | 11238986 |
| partial purification and characterization of pyruvate kinase from the plant fraction of soybean root nodules. | pyruvate kinase (pk, ec 2.7.1.40) was partially purified from the plant cytosolic fraction of n2-fixing soybean (glycine max [l.] merr.) root nodules. the partially purified pk preparation was completely free of contamination by phosphoenolpyruvate carboxylase (pepc, ec 4.1.1.31), the other major phosphoenolpyruvate (pep)-utilizing enzyme in legume root nodules. latency experiments with sonicated nodule extracts showed that bradyrhizobium japonicum bacteroids do not express either pk or pepc act ... | 2001 | 11240911 |
| determination of wolbachia genome size by pulsed-field gel electrophoresis. | genome sizes of six different wolbachia strains from insect and nematode hosts have been determined by pulsed-field gel electrophoresis of purified dna both before and after digestion with rare-cutting restriction endonucleases. enzymes smai, apai, asci, and fsei cleaved the studied wolbachia strains at a small number of sites and were used for the determination of the genome sizes of wmelpop, wmel, and wmelcs (each 1.36 mb), wri (1.66 mb), wbma (1.1 mb), and wdim (0.95 mb). the wolbachia genome ... | 2001 | 11244060 |
| new insight into the role of the phap phasin of ralstonia eutropha in promoting synthesis of polyhydroxybutyrate. | phasins are proteins that are proposed to play important roles in polyhydroxyalkanoate synthesis and granule formation. here the phasin phap of ralstonia eutropha has been analyzed with regard to its role in the synthesis of polyhydroxybutyrate (phb). purified recombinant phap, antibodies against phap, and an r. eutropha phap deletion strain have been generated for this analysis. studies with the phap deletion strain show that phap must accumulate to high levels in order to play its normal role ... | 2001 | 11244085 |
| agricultural microbes genome 2: first glimpses into the genomes of plant-associated microbes. | 2001 | 11251088 | |
| phosphatidylcholine levels in bradyrhizobium japonicum membranes are critical for an efficient symbiosis with the soybean host plant. | phosphatidylcholine (pc), the major membrane phospholipid in eukaryotes, is found in only some bacteria including members of the family rhizobiaceae. for this reason, it has long been speculated that rhizobial pc might be required for a successful interaction of rhizobia with their legume host plants in order to allow the formation of nitrogen-fixing root nodules. a major pathway for pc formation in prokaryotes involves a threefold methylation of the precursor phosphatidylethanolamine (pe). here ... | 2001 | 11251836 |
| genetic organization of the region encoding regulation, biosynthesis, and transport of rhizobactin 1021, a siderophore produced by sinorhizobium meliloti. | eight genes have been identified that function in the regulation, biosynthesis, and transport of rhizobactin 1021, a hydroxamate siderophore produced under iron stress by sinorhizobium meliloti. the genes were sequenced, and transposon insertion mutants were constructed for phenotypic analysis. six of the genes, named rhbabcdef, function in the biosynthesis of the siderophore and were shown to constitute an operon that is repressed under iron-replete conditions. another gene in the cluster, name ... | 2001 | 11274118 |
| a functional myo-inositol dehydrogenase gene is required for efficient nitrogen fixation and competitiveness of sinorhizobium fredii usda191 to nodulate soybean (glycine max [l.] merr.). | inositol derivative compounds provide a nutrient source for soil bacteria that possess the ability to degrade such compounds. rhizobium strains that are capable of utilizing certain inositol derivatives are better colonizers of their host plants. we have cloned and determined the nucleotide sequence of the myo-inositol dehydrogenase gene (idha) of sinorhizobium fredii usda191, the first enzyme responsible for inositol catabolism. the deduced idha protein has a molecular mass of 34,648 da and sho ... | 2001 | 11274120 |
| an internal region of the rpoh heat shock transcription factor is critical for rapid degradation by the ftsh protease. | the proteolysis of regulatory proteins plays an important role in the control of gene expression. the escherichia coli heat shock sigma factor rpoh (sigma(32)) is highly unstable. its instability is determined by interactions with the dnak chaperone machine, rna polymerase and the atp-dependent protease ftsh. bradyrhizobium japonicum expresses three rpoh proteins of which rpoh(1) is highly stable. to determine which regions of e. coli rpoh determine protein lability, we generated a number of tru ... | 2001 | 11277997 |
| investigating microbial (micro)colony heterogeneity by vibrational spectroscopy. | fourier transform infrared and raman microspectroscopy are currently being developed as new methods for the rapid identification of clinically relevant microorganisms. these methods involve measuring spectra from microcolonies which have been cultured for as little as 6 h, followed by the nonsubjective identification of microorganisms through the use of multivariate statistical analyses. to examine the biological heterogeneity of microorganism growth which is reflected in the spectra, measuremen ... | 2001 | 11282591 |
| evidence for direct interaction between enzyme i(ntr) and aspartokinase to regulate bacterial oligopeptide transport. | bradyrhizobium japonicum transports oligopeptides and the heme precursor delta-aminolevulinic acid (ala) by a common mechanism. two tn5-induced mutants disrupted in the lysc and ptsp genes were identified based on the inability to use prolyl-glycyl-glycine as a proline source and were defective in [(14)c]ala uptake activity. lysc and ptsp were shown to be proximal genes in the b. japonicum genome. however, rnase protection and in trans complementation analysis showed that lysc and ptsp are trans ... | 2001 | 11287431 |
| differential regulation of a family of apyrase genes from medicago truncatula. | four putative apyrase genes were identified from the model legume medicago truncatula. two of the genes identified from m. truncatula (mtapy1 and mtapy4) are expressed in roots and are inducible within 3 h after inoculation with sinorhizobium meliloti. the level of mrna expression of the other two putative apyrases, mtapy2 and mtapy3, was unaffected by rhizobial inoculation. screening of a bacterial artificial chromosome library of m. truncatula genomic dna showed that mtapy1, mtapy3, and mtapy4 ... | 2001 | 11299390 |
| case of localized recombination in 23s rrna genes from divergent bradyrhizobium lineages associated with neotropical legumes. | enzyme electrophoresis and rrna sequencing were used to analyze relationships of bradyrhizobium sp. nodule bacteria from four papilionoid legumes (clitoria javitensis, erythrina costaricensis, rhynchosia pyramidalis, and desmodium axillare) growing on barro colorado island (bci), panama. bacteria with identical multilocus allele profiles were commonly found in association with two or more legume genera. among the 16 multilocus genotypes (electrophoretic types [ets]) detected, six ets formed a cl ... | 2001 | 11319084 |
| dissimilatory nitrite reductase genes from autotrophic ammonia-oxidizing bacteria. | the presence of a copper-containing dissimilatory nitrite reductase gene (nirk) was discovered in several isolates of beta-subdivision ammonia-oxidizing bacteria using pcr and dna sequencing. pcr primers cunir3 and cunir4 were designed based on published nirk sequences from denitrifying bacteria and used to amplify a 540-bp fragment of the nirk gene from nitrosomonas marina and five additional isolates of ammonia-oxidizing bacteria. amplification products of the expected size were cloned and seq ... | 2001 | 11319103 |
| comparison of sequence analysis of 16s-23s rdna spacer regions, aflp analysis and dna-dna hybridizations in bradyrhizobium. | the sequences of the 16s-23s rdna intergenic spacer region of 62 strains of bradyrhizobium, including representatives of the three valid species, were determined. the majority of strains had a single rrna operon type and all contained a trna(ala) and a trna(ile) gene. analysis of the sequence data produced groupings in line with previously obtained aflp data. dna-dna hybridizations were performed to determine to what extent spacer sequences and aflp profiles reflected the overall genomic similar ... | 2001 | 11321108 |
| osmoregulated periplasmic glucans of erwinia chrysanthemi. | we report the initial characterization of the osmoregulated periplasmic glucans (opgs) of erwinia chrysanthemi. opgs are intrinsic components of the bacterial envelope necessary to the pathogenicity of this phytopathogenic enterobacterium (f. page, s. altabe, n. hugouvieux-cotte-pattat, j.-m. lacroix, j. robert-baudouy and j.-p. bohin, j. bacteriol. 183:0000-0000, 2001 [companion in this issue]). opgs were isolated by trichloracetic acid treatment and gel permeation chromatography. the synthesis ... | 2001 | 11325941 |
| [effect of certain environmental factors on bradyrhizobium japonicum]. | dependence of motility and chemotaxis was studied in two strains of bradyrhizobium japonicum upon several environmental factors. in both strains, chemotaxis was found to increase with an increasing concentration of the attractant (glucose) to 5.6 x 10(-2) m. both motility and chemotaxis reached their maximum in the two- to three-day cultures at neutral ph. the maximum motility of these bacteria occurred at 40 degrees c. the maximum values of chemotaxis in these microorganisms were, however, obse ... | 2001 | 11338826 |
| rhizobial nodl o-acetyl transferase and nods n-methyl transferase functionally interfere in production of modified nod factors. | the products of the rhizobial nodulation genes are involved in the biosynthesis of lipochitin oligosaccharides (lcos), which are host-specific signal molecules required for nodule formation. the presence of an o-acetyl group on c-6 of the nonreducing n-acetylglucosamine residue of lcos is due to the enzymatic activity of nodl. here we show that transfer of the nodl gene into four rhizobial species that all normally produce lcos that are not modified on c-6 of the nonreducing terminal residue res ... | 2001 | 11344149 |
| sugar-binding activity of pea lectin enhances heterologous infection of transgenic alfalfa plants by rhizobium leguminosarum biovar viciae. | transgenic alfalfa (medicago sativa l. cv regen) roots carrying genes encoding soybean lectin or pea (pisum sativum) seed lectin (psl) were inoculated with bradyrhizobium japonicum or rhizobium leguminosarum bv viciae, respectively, and their responses were compared with those of comparably inoculated control plants. we found that nodule-like structures formed on alfalfa roots only when the rhizobial strains produced nod factor from the alfalfa-nodulating strain, sinorhizobium meliloti. uninfect ... | 2001 | 11351077 |
| frankia kb5 possesses a hydrogenase immunologically related to membrane-bound. | the immunological relationship of the hydrogenase in frankia kb5 to hydrogenases in other microorganisms was investigated using antisera raised against holo-[nife]-hydrogenases isolated from alcaligenes latus, azotobacter vinelandii, ralstonia eutropha, and the small and large hydrogenase subunits from bradyrhizobium japonicum. the antisera raised against the a. latus, r. eutropha, and b. japonicum (large subunit) polypeptides were found to recognize two polypeptides, corresponding to the unproc ... | 2001 | 11381338 |
| changes in fatty acid composition and degree of unsaturation of (brady)rhizobia as a response to phases of growth, reduced water activities and mild desiccation. | the effects of growth phase, reductions in the water activity (a(w)) of the growth medium and mild desiccation on the composition and the degree of unsaturation of cellular fatty acids (cfa) of sinorhizobium meliloti, bradyrhizobium elkanii and bradyrhizobium japonicum were studied. during the course of growth, an interchange of cis-vaccenic with lactobacillic acid and a slight increase in palmitic acid were observed while other fatty acids remained constant. the degree of unsaturation was signi ... | 2001 | 11392487 |
| global versus local regulatory roles for lrp-related proteins: haemophilus influenzae as a case study. | lrp (leucine-responsive regulatory protein) plays a global regulatory role in escherichia coli, affecting expression of dozens of operons. numerous lrp-related genes have been identified in different bacteria and archaea, including asnc, an e. coli gene that was the first reported member of this family. pairwise comparisons of amino acid sequences of the corresponding proteins shows an average sequence identity of only 29% for the vast majority of comparisons. by contrast, lrp-related proteins f ... | 2001 | 11395465 |
| cloning, expression, and characterization of a neuraminidase gene from arcanobacterium pyogenes. | arcanobacterium pyogenes is an opportunistic pathogen, associated with suppurative infections in domestic animals. in addition to pyolysin, a pore-forming, cholesterol-binding toxin, a. pyogenes expresses a number of putative virulence factors, including several proteases and neuraminidase activity. a 3,009-bp gene, nanh, was cloned and sequenced and conferred neuraminidase activity on an escherichia coli host strain. the predicted 107-kda nanh protein displayed similarity to a number of bacteri ... | 2001 | 11401983 |
| the three-dimensional structure of cystathionine beta-lyase from arabidopsis and its substrate specificity. | the pyridoxal 5'-phosphate-dependent enzyme cystathionine beta-lyase (cbl) catalyzes the penultimate step in the de novo biosynthesis of met in microbes and plants. absence of cbl in higher organisms makes it an important target for the development of antibiotics and herbicides. the three-dimensional structure of cystathionine beta-lyase from arabidopsis was determined by patterson search techniques, using the structure of tobacco (nicotiana tabacum) cystathionine gamma-synthase as starting poin ... | 2001 | 11402193 |
| purification, characterization, and genetic analysis of cu-containing dissimilatory nitrite reductase from a denitrifying halophilic archaeon, haloarcula marismortui. | cu-containing dissimilatory nitrite reductase (cunir) was purified from denitrifying cells of a halophilic archaeon, haloarcula marismortui. the purified cunir appeared blue in the oxidized state, possessing absorption peaks at 600 and 465 nm in the visible region. electron paramagnetic resonance spectroscopy suggested the presence of type 1 cu (g(ii) = 2.232; a(ii) = 4.4 mt) and type 2 cu centers (g(ii) = 2.304; a(ii) = 13.3 mt) in the enzyme. the enzyme contained two subunits, whose apparent m ... | 2001 | 11418554 |
| accumulation of the phap phasin of ralstonia eutropha is dependent on production of polyhydroxybutyrate in cells. | polyhydroxyalkanoates (phas) are polyoxoesters that are produced by diverse bacteria and that accumulate as intracellular granules. phasins are granule-associated proteins that accumulate to high levels in strains that are producing phas. the accumulation of phasins has been proposed to be dependent on pha production, a model which is now rigorously tested for the phasin phap of ralstonia eutropha. r. eutropha phac pha synthase and phap phasin gene replacement strains were constructed. the strai ... | 2001 | 11418562 |
| the origin and early evolution of mitochondria. | complete sequences of numerous mitochondrial, many prokaryotic, and several nuclear genomes are now available. these data confirm that the mitochondrial genome originated from a eubacterial (specifically alpha-proteobacterial) ancestor but raise questions about the evolutionary antecedents of the mitochondrial proteome. | 2001 | 11423013 |
| photosynthetic and phylogenetic primers for detection of anoxygenic phototrophs in natural environments. | primer sets were designed to target specific 16s ribosomal dna (rdna) sequences of photosynthetic bacteria, including the green sulfur bacteria, the green nonsulfur bacteria, and the members of the heliobacteriaceae (a gram-positive phylum). due to the phylogenetic diversity of purple sulfur and purple nonsulfur phototrophs, the 16s rdna gene was not an appropriate target for phylogenetic rdna primers. thus, a primer set was designed that targets the pufm gene, encoding the m subunit of the phot ... | 2001 | 11425703 |
| trehalose becomes the most abundant non-structural carbohydrate during senescence of soybean nodules. | carbohydrate metabolism and symbiont survival were studied in nodules of soybean (g. max [l.] merr. cv. maple arrow infected with bradyrhizobium japonicum 61-a-101), induced to senesce simultaneously by application of the photosynthesis inhibitor dichloromethyl urea (dcmu). the plant-borne carbohydrates sucrose and starch started to decline after 2 d and reached background levels after 8 d, in parallel with the decline of nitrogenase. however, the microsymbiont-borne disaccharide trehalose decli ... | 2001 | 11432911 |
| mechanistic basis for suicide inactivation of porphobilinogen synthase by 4,7-dioxosebacic acid, an inhibitor that shows dramatic species selectivity. | 4,7-dioxosebacic acid (4,7-dosa) is an active site-directed irreversible inhibitor of porphobilinogen synthase (pbgs). pbgs catalyzes the first common step in the biosynthesis of the tetrapyrrole cofactors such as heme, vitamin b(12), and chlorophyll. 4,7-dosa was designed as an analogue of a proposed reaction intermediate in the physiological pbgs-catalyzed condensation of two molecules of 5-aminolevulinic acid. as shown here, 4,7-dosa exhibits time-dependent and dramatic species-specific inhib ... | 2001 | 11444968 |
| binding site for chitin oligosaccharides in the soybean plasma membrane. | affinity cross-linking of the plasma membrane fraction to an (125)i-labeled chitin oligosaccharide led to the identification and characterization of an 85-kd, chitin binding protein in plasma membrane-enriched fractions from both suspension-cultured soybean cells and root tissue. inhibition analysis indicated a binding preference for larger (i.e. degrees of polymerization = 8) n-acetylated chitin molecules with a 50% inhibition of initial activity value of approximately 50 nm. n-acetyl-glucosami ... | 2001 | 11457966 |
| pas kinase: an evolutionarily conserved pas domain-regulated serine/threonine kinase. | pas domains regulate the function of many intracellular signaling pathways in response to both extrinsic and intrinsic stimuli. pas domain-regulated histidine kinases are common in prokaryotes and control a wide range of fundamental physiological processes. similarly regulated kinases are rare in eukaryotes and are to date completely absent in mammals. pas kinase (pask) is an evolutionarily conserved gene product present in yeast, flies, and mammals. the amino acid sequence of pask specifies two ... | 2001 | 11459942 |
| fructose uptake in sinorhizobium meliloti is mediated by a high-affinity atp-binding cassette transport system. | by transposon mutagenesis, we have isolated a mutant of sinorhizobium meliloti which is totally unable to grow on fructose as sole carbon source as a consequence of its inability to transport this sugar. the cloning and sequencing analysis of the chromosomal dna region flanking the tnphoa insertion revealed the presence of six open reading frames (orfs) organized in two loci, frcrs and frcbcak, transcribed divergently. the frcbca genes encode the characteristic components of an atp-binding casse ... | 2001 | 11466273 |
| membrane topology of the streptomyces lividans type i signal peptidases. | most bacterial membranes contain one or two type i signal peptidases (spases) for the removal of signal peptides from export proteins. for streptomyces lividans, four different type i spases (denoted sipw, sipx, sipy, and sipz) were previously described. in this communication, we report the experimental determination of the membrane topology of these spases. a protease protection assay of spase tendamistat fusions confirmed the presence of the n- as well as the c-terminal transmembrane anchor fo ... | 2001 | 11466278 |
| characterization of soybean bradyrhizobia for which serogroup affinities have not been identified. | the usda, ars national rhizobium germplasm collection contains 143 accessions of slow-growing soybean strains among which there are 17 distinct serological groups. however, 11 strains appear to have no serological affinity with the 17 serogroups. therefore, we determined whether these strains were diverse and examined their phylogenetic placement. nine strains formed nitrogen-fixing symbioses with soybean indicating that these accessions were not contaminants. we concluded from results of amplif ... | 2001 | 11467727 |
| specific detection of bradyrhizobium and rhizobium strains colonizing rice (oryza sativa) roots by 16s-23s ribosomal dna intergenic spacer-targeted pcr. | in addition to forming symbiotic nodules on legumes, rhizobial strains are members of soil or rhizosphere communities or occur as endophytes, e.g., in rice. two rhizobial strains which have been isolated from root nodules of the aquatic legumes aeschynomene fluminensis (irbg271) and sesbania aculeata (irbg74) were previously found to promote rice growth. in addition to analyzing their phylogenetic positions, we assessed the suitability of the 16s-23s ribosomal dna (rdna) intergenic spacer (igs) ... | 2001 | 11472944 |
| enrichment of high-affinity co oxidizers in maine forest soil. | carboxydotrophic activity in forest soils was enriched by incubation in a flowthrough system with elevated concentrations of headspace co (40 to 400 ppm). co uptake increased substantially over time, while the apparent k(m) ((app)k(m)) for uptake remained similar to that of unenriched soils (<10 to 20 ppm). carboxydotrophic activity was transferred to and further enriched in sterile sand and forest soil. the (app)k(m)s for secondary and tertiary enrichments remained similar to values for unenric ... | 2001 | 11472946 |
| isolation and regulation of sinorhizobium meliloti 1021 loci induced by oxygen limitation. | eleven sinorhizobium meliloti 1021 loci whose expression was induced under low oxygen concentrations were identified in a collection of 5,000 strains carrying tn5-1063 (luxab) transcriptional reporter gene fusions. the 11 tn5-1063-tagged loci were cloned and characterized. the dependence of the expression of the tagged loci on the fixl/fixj oxygen-sensing two-component regulatory system was examined. three of the loci were found to be dependent upon fixl and fixj for their expression, while one ... | 2001 | 11472955 |
| rose elements occur in disparate rhizobia and are functionally interchangeable between species. | expression of at least ten genes in bradyrhizobium japonicum, seven of which code for small heat shock proteins (shsps), is under the control of rose (repression of heat shock gene expression). this negatively cis-acting dna element confers temperature control to a sigma(70)-type promoter. here, we show that rose elements are not restricted to b. japonicum but are also present in bradyrhizobium sp. (parasponia), rhizobium sp. strain ngr234 and mesorhizobium loti. an overall alignment of all rose ... | 2001 | 11479702 |
| the nir, nor, and nos denitrification genes are dispersed over the bradyrhizobium japonicum chromosome. | cleavage of genomic dna from bradyrhizobium japonicum strain 3i1b110 by the restriction enzymes pmei, paci, and swai has been used together with pulsed-field gel electrophoresis and southern hybridization to locate the nirk, norcbqd, and nosrzdfylx denitrification genes on the chromosomal map of b. japonicum strain 110spc4. mutant strains grk13, grc131, and grz25 were obtained by insertion of plasmid puc4-kixx-aphii-psp, which carries recognition sites for the enzymes paci, pmei and swai, into t ... | 2001 | 11479713 |
| analysis of the chromosome sequence of the legume symbiont sinorhizobium meliloti strain 1021. | sinorhizobium meliloti is an alpha-proteobacterium that forms agronomically important n(2)-fixing root nodules in legumes. we report here the complete sequence of the largest constituent of its genome, a 62.7% gc-rich 3,654,135-bp circular chromosome. annotation allowed assignment of a function to 59% of the 3,341 predicted protein-coding orfs, the rest exhibiting partial, weak, or no similarity with any known sequence. unexpectedly, the level of reiteration within this replicon is low, with onl ... | 2001 | 11481430 |
| the complete sequence of the 1,683-kb psymb megaplasmid from the n2-fixing endosymbiont sinorhizobium meliloti. | analysis of the 1,683,333-nt sequence of the psymb megaplasmid from the symbiotic n(2)-fixing bacterium sinorhizobium meliloti revealed that the replicon has a high gene density with a total of 1,570 protein-coding regions, with few insertion elements and regions duplicated elsewhere in the genome. the only copies of an essential arg-trna gene and the mincde genes are located on psymb. almost 20% of the psymb sequence carries genes encoding solute uptake systems, most of which were of the atp-bi ... | 2001 | 11481431 |
| nucleotide sequence and predicted functions of the entire sinorhizobium meliloti psyma megaplasmid. | the symbiotic nitrogen-fixing soil bacterium sinorhizobium meliloti contains three replicons: psyma, psymb, and the chromosome. we report here the complete 1,354,226-nt sequence of psyma. in addition to a large fraction of the genes known to be specifically involved in symbiosis, psyma contains genes likely to be involved in nitrogen and carbon metabolism, transport, stress, and resistance responses, and other functions that give s. meliloti an advantage in its specialized niche. | 2001 | 11481432 |
| a marker-dense physical map of the bradyrhizobium japonicum genome. | bacterial artificial chromosome (bac) clones are effective mapping and sequencing reagents for use with a wide variety of small and large genomes. this report describes the development of a physical framework for the genome of bradyrhizobium japonicum, the nitrogen-fixing symbiont of soybean. a bac library for b. japonicum was constructed that provides a 77-fold genome coverage based on an estimated genome size of 8.7 mb. the library contains 4608 clones with an average insert size of 146 kb. to ... | 2001 | 11483585 |
| dna-dna hybridization study of bradyrhizobium strains. | dna-dna hybridizations were performed between bradyrhizobium strains, isolated mainly from faidherbia albida and aeschynomene species, as well as bradyrhizobium reference strains. results indicated that the genus bradyrhizobium consists of at least 11 genospecies, i to xi. the genospecies formed four subgeneric groups that were more closely related to each other (>40% dna hybridization) than to other genospecies (<40% dna hybridization): (i) genospecies i (bradyrhizobium japonicum), iii (bradyrh ... | 2001 | 11491327 |
| dnak chaperone-mediated control of activity of a sigma(32) homolog (rpoh) plays a major role in the heat shock response of agrobacterium tumefaciens. | rpoh (escherichia coli sigma(32) and its homologs) is the central regulator of the heat shock response in gram-negative proteobacteria. here we studied salient regulatory features of rpoh in agrobacterium tumefaciens by examining its synthesis, stability, and activity while increasing the temperature from 25 to 37 degrees c. heat induction of rpoh synthesis occurred at the level of transcription from an rpoh-dependent promoter, coordinately with that of dnak, and followed by an increase in the r ... | 2001 | 11514513 |
| crystallization and preliminary diffraction studies of native and selenomethionine ccmg (cycy, dsbe). | disulfide-bond (dsb) proteins are a family of redox proteins containing a cys-x-x-cys motif. they are essential for disulfide-bond exchange in the bacterial periplasm and are necessary for the correct folding and function of many secreted proteins. ccmg (dsbe) is a reducing dsb protein required for cytochrome c maturation. crystals of bradyrhizobium japonicum ccmg have been obtained that diffract x-rays to 1.14 a resolution. the crystals are orthorhombic, space group p2(1)2(1)2(1), with unit-cel ... | 2001 | 11526323 |
| bradyrhizobium japonicum mutants defective in cyclic beta-glucan synthesis show enhanced sensitivity to plant defense responses. | susceptibility of the nitrogen-fixing soybean symbiont bradyrhizobium japonicum to inducible plant defense metabolites such as phytoalexin and h2o2, was investigated. on the wild-type strain usda 110 the soybean phytoalexin, glyceollin, showed bacteriostatic activity. viable bacteria isolated from intact nodules were adapted to glyceollin. h2o2 in physiological concentrations did not affect wild-type bacteria. b. japonicum mutants defective in the biosynthesis of cyclic beta-(1-->3)-(1-->6)-gluc ... | 2001 | 11531093 |
| structure of the soluble domain of a membrane-anchored thioredoxin-like protein from bradyrhizobium japonicum reveals unusual properties. | tlpa is an unusual thioredoxin-like protein present in the nitrogen-fixing soil bacterium bradyrhizobium japonicum. a hydrophobic n-terminal transmembrane domain anchors it to the cytoplasmic membrane, whereby the hydrophilic thioredoxin domain becomes exposed to the periplasmic space. there, tlpa catalyses an essential reaction, probably a reduction, in the biogenesis of cytochrome aa(3). the soluble thioredoxin domain (tlpa(sol)), devoid of the membrane anchor, was purified and crystallized. o ... | 2001 | 11531338 |
| discovery of a haem uptake system in the soil bacterium bradyrhizobium japonicum. | in bradyrhizobium japonicum, the nitrogen-fixing symbiont of soybeans, we have identified a haem uptake system, hmu, that comprises a cluster of nine open reading frames. predicted products of these genes include: hmur, a tonb-dependent haem receptor in the outer membrane; hmut, a periplasmic haem-binding protein; and hmuuv, an abc transporter in the inner membrane. furthermore, we identified homologues of exbbd and tonb, that are required for energy transduction from the inner to the outer memb ... | 2001 | 11532144 |
| identification of the heat-shock sigma factor rpoh and a second rpoh-like protein in sinorhizobium meliloti. | hybridization to a pcr product derived from conserved sigma-factor sequences led to the identification of two sinorhizobium meliloti dna segments that display significant sequence similarity to the family of rpoh genes encoding the sigma(32) (rpoh) heat-shock transcription factors. the first gene, rpoh1, complements an escherichia coli rpoh mutation. cells containing an rpoh1 mutation are impaired in growth at 37 degrees c under free-living conditions and are defective in nitrogen fixation durin ... | 2001 | 11535780 |
| binding of transcriptional activators to sigma 54 in the presence of the transition state analog adp-aluminum fluoride: insights into activator mechanochemical action. | conformational changes in sigma 54 (sigma(54)) and sigma(54)-holoenzyme depend on nucleotide hydrolysis by an activator. we now show that sigma(54) and its holoenzyme bind to the central atp-hydrolyzing domains of the transcriptional activators pspf and nifa in the presence of adp-aluminum fluoride, an analog of atp in the transition state for hydrolysis. direct binding of sigma(54) region i to activator in the presence of adp-aluminum fluoride was shown and inferred from in vivo suppression gen ... | 2001 | 11544185 |
| identification, characterization, and functional analysis of a gene encoding the ferric uptake regulation protein in bartonella species. | environmental iron concentrations coordinately regulate transcription of genes involved in iron acquisition and virulence via the ferric uptake regulation (fur) system. we identified and sequenced the fur gene and flanking regions of three bartonella species. the most notable difference between bartonella fur and other fur proteins was a substantially higher predicted isoelectric point. no promoter activity or fur autoregulation was detected using a gfp reporter gene fused to the 204 nucleotides ... | 2001 | 11544240 |
| ferrochelatase is present in brucella abortus and is critical for its intracellular survival and virulence. | brucella spp. are pathogenic bacteria that cause brucellosis, an animal disease which can also affect humans. although understanding the pathogenesis is important for the health of animals and humans, little is known about virulence factors associated with it. in order for chronic disease to be established, brucella spp. have developed the ability to survive inside phagocytes by evading cell defenses. it hides inside vacuoles, where it then replicates, indicating that it has an active metabolism ... | 2001 | 11553564 |
| role of glutamine synthetase in nitrogen metabolite repression in aspergillus nidulans. | glutamine synthetase (gs), ec 6.3.1.2, is a central enzyme in the assimilation of nitrogen and the biosynthesis of glutamine. we have isolated the aspergillus nidulans glna gene encoding gs and have shown that glna encodes a highly expressed but not highly regulated mrna. inactivation of glna results in an absolute glutamine requirement, indicating that gs is responsible for the synthesis of this essential amino acid. even when supplemented with high levels of glutamine, strains lacking a functi ... | 2001 | 11566979 |
| the c terminus of sigma(32) is not essential for degradation by ftsh. | a key step in the regulation of heat shock genes in escherichia coli is the stress-dependent degradation of the heat shock promoter-specific sigma(32) subunit of rna polymerase by the aaa protease, ftsh. previous studies implicated the c termini of protein substrates, including sigma(32), as degradation signals for aaa proteases. we investigated the role of the c terminus of sigma(32) in ftsh-dependent degradation by analysis of c-terminally truncated sigma(32) mutant proteins. deletion of the 5 ... | 2001 | 11566990 |
| eubacterial diterpene cyclase genes essential for production of the isoprenoid antibiotic terpentecin. | a gene cluster containing the mevalonate pathway genes (open reading frame 2 [orf2] to orf7) for the formation of isopentenyl diphosphate and a geranylgeranyl diphosphate (ggdp) synthase gene (orf1) had previously been cloned from streptomyces griseolosporeus strain mf730-n6, a diterpenoid antibiotic, terpentecin (tp) producer (y. hamano, t. dairi, m. yamamoto, t. kawasaki, k kaneda, t. kuzuyama, n. itoh, and h. seto, biosci. biotech. biochem. 65:1627-1635, 2001). sequence analysis in the upstre ... | 2001 | 11567009 |
| response of the endophytic diazotroph gluconacetobacter diazotrophicus on solid media to changes in atmospheric partial o(2) pressure. | gluconacetobacter diazotrophicus is an n(2)-fixing endophyte isolated from sugarcane. g. diazotrophicus was grown on solid medium at atmospheric partial o(2) pressures (po(2)) of 10, 20, and 30 kpa for 5 to 6 days. using a flowthrough gas exchange system, nitrogenase activity and respiration rate were then measured at a range of atmospheric po(2) (5 to 60 kpa). nitrogenase activity was measured by h(2) evolution in n(2)-o(2) and in ar-o(2), and respiration rate was measured by co(2) evolution in ... | 2001 | 11571174 |
| detection and enumeration of methanotrophs in acidic sphagnum peat by 16s rrna fluorescence in situ hybridization, including the use of newly developed oligonucleotide probes for methylocella palustris. | two 16s rrna-targeted oligonucleotide probes, mcell-1026 and mcell-181, were developed for specific detection of the acidophilic methanotroph methylocella palustris using fluorescence in situ hybridization (fish). the fluorescence signal of probe mcell-181 was enhanced by its combined application with the oligonucleotide helper probe h158. mcell-1026 and mcell-181, as well as 16s rrna oligonucleotide probes with reported group specificity for either type i methanotrophs (probes m-84 and m-705) o ... | 2001 | 11571193 |
| feedback regulation of the bradyrhizobium japonicum nodulation genes. | lipochitin nod signals are produced by rhizobia and are required for the establishment of a nitrogen-fixing symbiosis with a legume host. the nodulation genes encode products required for the synthesis of this signal and are induced in response to plant-produced flavonoid compounds. the addition of chitin and lipo-chitin oligomers to bradyrhizobium japonicum cultures resulted in a significant reduction in the expression of a nod-lacz fusion. intracellular expression of nodc, encoding a chitin sy ... | 2001 | 11580840 |
| interactive control of rhodobacter capsulatus redox-balancing systems during phototrophic metabolism. | in nonsulfur purple bacteria, redox homeostasis is achieved by the coordinate control of various oxidation-reduction balancing mechanisms during phototrophic anaerobic respiration. in this study, the ability of rhodobacter capsulatus to maintain a balanced intracellular oxidation-reduction potential was considered; in addition, interrelationships between the control of known redox-balancing systems, the calvin-benson-bassham, dinitrogenase and dimethyl sulfoxide reductase systems, were probed in ... | 2001 | 11591679 |
| heme utilization in bordetella avium is regulated by rhui, a heme-responsive extracytoplasmic function sigma factor. | efficient utilization of heme as an iron (fe) source by bordetella avium requires bhur, an fe-regulated gene which encodes an outer membrane heme receptor. upstream of bhur is a 507-bp open reading frame, hereby designated rhui (for regulator of heme uptake), which codes for a 19-kda polypeptide. whereas the 19-kda polypeptide had homology to a subfamily of alternative sigma factors known as the extracytoplasmic function (ecf) sigma factors, it was hypothesized that rhui encoded a potential in-t ... | 2001 | 11598070 |
| effects of trifluralin on soil microbial populations and the nitrogen fixation activities. | effects of trifluralin on soil microbial populations and the nitrogen fixation activity of nitrogen-fixing bacteria azotobacter chroococcum and bradyrhizobium japonicum and the decomposition of trifluralin by soil microorganisms were studied. trifluralin at lower concentrations from 0.5 mg microg(-1) dry soil to lower than 10.0 mg microg(-1) dry soil appeared to stimulate the growth of soil bacteria, actinomycetes, mould, and the pure cultures of br. japonicum and a. chroococcum. not only the co ... | 2001 | 11599721 |
| population density-dependent regulation of the bradyrhizobium japonicum nodulation genes. | the nodulation genes of bradyrhizobium japonicum are essential for infection and establishment of a nitrogen-fixing symbiosis. here, we demonstrate that plant-produced isoflavones induce nodulation gene expression in a population density-dependent fashion. nodulation gene induction is highest at a low population density and significantly reduced in more dense cultures. a quorum signal molecule in the conditioned medium of b. japonicum cultures mediates this repression. repression in response to ... | 2001 | 11679065 |
| dna sequence and mutational analysis of rhizobitoxine biosynthesis genes in bradyrhizobium elkanii. | we cloned and sequenced a cluster of genes involved in the biosynthesis of rhizobitoxine, a nodulation enhancer produced by bradyrhizobium elkanii. the nucleotide sequence of the cloned 28.4-kb dna region encompassing rtxa showed that several open reading frames (orfs) were located downstream of rtxa. a large-deletion mutant of b. elkanii, usda94 delta rtx::omega 1, which lacks rtxa, orf1 (rtxc), orf2, and orf3, did not produce rhizobitoxine, dihydrorhizobitoxine, or serinol. the broad-host-rang ... | 2001 | 11679318 |
| expression of a pseudomonas putida aminotransferase involved in lysine catabolism is induced in the rhizosphere. | using a transposon carrying a promoterless lux operon to generate transcriptional fusions by insertional mutagenesis, we have identified a pseudomonas putida gene with increased expression in the presence of corn root exudates. expression of the transcriptional fusion, induced by the amino acid lysine, was detected in p. putida in the rhizosphere of plants as well as in response to seed exudates. the mutant was unable to grow on lysine or delta-aminovalerate as carbon sources, which indicates th ... | 2001 | 11679348 |
| endophytic colonization and in planta nitrogen fixation by a herbaspirillum sp. isolated from wild rice species. | nitrogen-fixing bacteria were isolated from the stems of wild and cultivated rice on a modified rennie medium. based on 16s ribosomal dna (rdna) sequences, the diazotrophic isolates were phylogenetically close to four genera: herbaspirillum, ideonella, enterobacter, and azospirillum. phenotypic properties and signature sequences of 16s rdna indicated that three isolates (b65, b501, and b512) belong to the herbaspirillum genus. to examine whether herbaspirillum sp. strain b501 isolated from wild ... | 2001 | 11679357 |
| recovery and phylogenetic analysis of nifh sequences from diazotrophic bacteria associated with dead aboveground biomass of spartina alterniflora. | dna was extracted from dry standing dead spartina alterniflora stalks as well as dry spartina wrack from the north inlet (south carolina) and sapelo island (georgia) salt marshes. partial nifh sequences were pcr amplified, the products were separated by denaturing gradient gel electrophoresis (dgge), and the prominent dgge bands were sequenced. most sequences (109 of 121) clustered with those from alpha-proteobacteria, and 4 were very similar (>99%) to that of azospirillum brasilense. seven sequ ... | 2001 | 11679360 |
| characterization of the nirk gene encoding the respiratory, cu-containing nitrite reductase of bradyrhizobium japonicum. | the structural gene, nirk, for the respiratory cu-containing nitrite reductase from bradyrhizobium japonicum usda110 has been isolated and sequenced. the deduced amino acid sequence exhibited a high degree of similarity to other cu-containing nitrite reductases from various sources. the full-length protein included a signal peptide for protein export. analysis of the sequence upstream from the structural nirk gene revealed the presence of an anaerobox located 83 base pairs from the putative tran ... | 2001 | 11690645 |
| [cloning and functional analysis of glnb from azospirillum brasilense yu62]. | the glnb gene of a. brasilense yu62 was determined in a 3.7 kb ecori + psti fragment. the glna is located downstream of glnb and an orf for hypothetical protein is on upstream of glnb. the deduced amino acid sequence of pii encoded by glnb is 71%, 77%, 79% and 69% identical to that of k. pneumoniae, bradyrhizobium japonicum, rhizobium leguninosarum and e. coli, respectively. a km-casette was inserted into bglii site of glnb coding region and glnb- mutant was obtained by homologous recombination. ... | 2001 | 11695269 |
| elevated temperature differentially affects virulence, virb protein accumulation, and t-pilus formation in different agrobacterium tumefaciens and agrobacterium vitis strains. | that gene transfer to plant cells is a temperature-sensitive process has been known for more than 50 years. previous work indicated that this sensitivity results from the inability to assemble a functional t pilus required for t-dna and protein transfer to recipient cells. the studies reported here extend these observations and more clearly define the molecular basis of this assembly and transfer defect. t-pilus assembly and virulence protein accumulation were monitored in agrobacterium tumefaci ... | 2001 | 11698374 |
| evidence for the production of chemical compounds analogous to nod factor by the silicate bacterium bacillus circulans gy92. | silicate bacteria are generally placed in the species bacillus circulans and are widely used in biological fertilisers and biological leaching. the bacteria can form conspicuous amounts of extracellular polysaccharides in nitrogen-free media or in the presence of substrates with large c/n ratios. using high performance liquid chromatography, we have shown that b. circulans produced a new peak/compound when induced with the plant-to-bacteria signal molecule genistein. this material co-eluted with ... | 2001 | 11716218 |
| regulation of gene expression in response to oxygen in rhizobium etli: role of fnrn in fixnoqp expression and in symbiotic nitrogen fixation. | previously, we reported finding duplicated fixnoqp operons in rhizobium etli cfn42. one of these duplicated operons is located in the symbiotic plasmid (fixnoqpd), while the other is located in a cryptic plasmid (fixnoqpf). although a novel fixl-fixkf regulatory cascade participates in microaerobic expression of both fixnoqp duplicated operons, we found that a mutation in fixl eliminates fixnoqpf expression but has only a moderate effect on expression of fixnoqpd. this suggests that there are di ... | 2001 | 11717256 |
| cytochromes c(550), c(552), and c(1) in the electron transport network of paracoccus denitrificans: redundant or subtly different in function? | paracoccus denitrificans strains with mutations in the genes encoding the cytochrome c(550), c(552), or c(1) and in combinations of these genes were constructed, and their growth characteristics were determined. each mutant was able to grow heterotrophically with succinate as the carbon and free-energy source, although their specific growth rates and maximum cell numbers fell variably behind those of the wild type. maximum cell numbers and rates of growth were also reduced when these strains wer ... | 2001 | 11717258 |
| identification of essential amino acids in the azorhizobium caulinodans fucosyltransferase nodz. | the nodz gene, which is present in various rhizobial species, is involved in the addition of a fucose residue in an alpha 1-6 linkage to the reducing n-acetylglucosamine residue of lipo-chitin oligosaccharide signal molecules, the so-called nod factors. fucosylation of nod factors is known to affect nodulation efficiency and host specificity. despite a lack of overall sequence identity, nodz proteins share conserved peptide motifs with mammalian and plant fucosyltransferases that participate in ... | 2001 | 11717264 |
| involvement of hyp gene products in maturation of the h(2)-sensing [nife] hydrogenase of ralstonia eutropha. | the biosynthesis of [nife] hydrogenases is a complex process that requires the function of the hyp proteins hypa, hypb, hypc, hypd, hype, hypf, and hypx for assembly of the h(2)-activating [nife] site. in this study we examined the maturation of the regulatory hydrogenase (rh) of ralstonia eutropha. the rh is a h(2)-sensing [nife] hydrogenase and is required as a constituent of a signal transduction chain for the expression of two energy-linked [nife] hydrogenases. here we demonstrate that the r ... | 2001 | 11717266 |
| differential roles of the pseudomonas aeruginosa pa14 rpon gene in pathogenicity in plants, nematodes, insects, and mice. | we cloned the rpon (ntra, glnf) gene encoding the alternate sigma factor sigma(54) from the opportunistic multihost pathogen pseudomonas aeruginosa strain pa14. a marker exchange protocol was used to construct the pa14 rpon insertional mutation rpon::gen(r). pa14 rpon::gen(r) synthesized reduced levels of pyocyanin and displayed a variety of phenotypes typical of rpon mutants, including a lack of motility and the failure to grow on nitrate, glutamate, or histidine as the sole nitrogen source. co ... | 2001 | 11717271 |
| improved soybean root association of n-starved bradyrhizobium japonicum. | in this study, we addressed the effects of n limitation in bradyrhizobium japonicum for its association with soybean roots. the wild-type strain lp 3001 grew for six generations with a growth rate of 1.2 day(-1) in a minimal medium with 28 mm mannitol as the carbon source and with the n source [(nh(4))(2)so(4)] limited to only 20 microm. under these conditions, the glutamine synthetase (gs) activity was five to six times higher than in similar cultures grown with 1 or 0.1 mm (nh(4))(2)so(4). the ... | 2001 | 11717284 |
| induction of h(2)o(2) synthesis by beta-glucan elicitors in soybean is independent of cytosolic calcium transients. | soybean cell suspension cultures have been used to investigate the role of the elevation of the cytosolic ca(2+) concentration in beta-glucan elicitors-induced defence responses, such as h(2)o(2) and phytoalexin production. the intracellular ca(2+) concentration was monitored in transgenic cells expressing the ca(2+)-sensing aequorin. two lines of evidence showed that a transient increase of the cytosolic ca(2+) concentration is not necessarily involved in the induction of h(2)o(2) generation: ( ... | 2001 | 11718714 |
| identification of active site residues in bradyrhizobium japonicum acetyl-coa synthetase. | acetyl-coa synthetase (acs) catalyses the activation of acetate to acetyl-coa in the presence of atp and coa. the gene encoding bradyrhyzobium japonicum acs has been cloned, sequenced, and expressed in escherichia coli. the enzyme comprises 648 amino acid residues with a calculated molecular mass of 71,996 da. the recombinant enzyme was also purified from the transformed e. coli. the enzyme was essentially indistinguishable from the acs of b. japonicum bacteroids as to the criteria of polyacryla ... | 2001 | 11726281 |
| a mrna-based thermosensor controls expression of rhizobial heat shock genes. | expression of several heat shock operons, mainly coding for small heat shock proteins, is under the control of rose (repression of heat shock gene expression) in various rhizobial species. this negatively cis-acting element confers temperature control by preventing expression at physiological temperatures. we provide evidence that rose-mediated regulation occurs at the post-transcriptional level. a detailed mutational analysis of rose(1)-hspa translationally fused to lacz revealed that its highl ... | 2001 | 11726689 |
| dynamics of genome architecture in rhizobium sp. strain ngr234. | bacterial genomes are usually partitioned in several replicons, which are dynamic structures prone to mutation and genomic rearrangements, thus contributing to genome evolution. nevertheless, much remains to be learned about the origins and dynamics of the formation of bacterial alternative genomic states and their possible biological consequences. to address these issues, we have studied the dynamics of the genome architecture in rhizobium sp. strain ngr234 and analyzed its biological significa ... | 2002 | 11741857 |
| site-specific integrative elements of rhizobiophage 16-3 can integrate into proline trna (cgg) genes in different bacterial genera. | the integrase protein of the rhizobium meliloti 41 phage 16-3 has been classified as a member of the int family of tyrosine recombinases. the site-specific recombination system of the phage belongs to the group in which the target site of integration (attb) is within a trna gene. since trna genes are conserved, we expected that the target sequence of the site-specific recombination system of the 16-3 phage could occur in other species and integration could take place if the required putative hos ... | 2002 | 11741858 |
| degradation of aromatics and chloroaromatics by pseudomonas sp. strain b13: purification and characterization of 3-oxoadipate:succinyl-coenzyme a (coa) transferase and 3-oxoadipyl-coa thiolase. | the degradation of 3-oxoadipate in pseudomonas sp. strain b13 was investigated and was shown to proceed through 3-oxoadipyl-coenzyme a (coa) to give acetyl-coa and succinyl-coa. 3-oxoadipate:succinyl-coa transferase of strain b13 was purified by heat treatment and chromatography on phenyl-sepharose, mono-q, and superose 6 gels. estimation of the native molecular mass gave a value of 115,000 +/- 5,000 da with a superose 12 column. polyacrylamide gel electrophoresis under denaturing conditions res ... | 2002 | 11741862 |
| degradation of aromatics and chloroaromatics by pseudomonas sp. strain b13: cloning, characterization, and analysis of sequences encoding 3-oxoadipate:succinyl-coenzyme a (coa) transferase and 3-oxoadipyl-coa thiolase. | 3-oxoadipate:succinyl-coenzyme a (coa) transferase and 3-oxoadipyl-coa thiolase carry out the ultimate steps in the conversion of benzoate and 3-chlorobenzoate to tricarboxylic acid cycle intermediates in bacteria utilizing the 3-oxoadipate pathway. this report describes the characterization of dna fragments with the overall length of 5.9 kb from pseudomonas sp. strain b13 that encode these enzymes. dna sequence analysis revealed five open reading frames (orfs) plus an incomplete one. orf1, of u ... | 2002 | 11741863 |
| characterization of a family of arabidopsis genes related to xyloglucan fucosyltransferase1. | to understand primary cell wall assembly in arabidopsis, we have focused on identifying and characterizing enzymes involved in xyloglucan biosynthesis. nine genes (atfut2-10) were identified that share between 47% and 62% amino acid similarity with the xyloglucan-specific fucosyltransferase atfut1. reverse transcriptase-pcr analysis indicates that all these genes are expressed. bioinformatic analysis predicts that these family members are fucosyltransferases, and we first hypothesized that some ... | 2001 | 11743104 |
| transcriptional activation of the rhodobacter sphaeroides cytochrome c(2) gene p2 promoter by the response regulator prra. | anoxygenic photosynthetic growth of rhodobacter sphaeroides, a member of the alpha subclass of the class proteobacteria, requires the response regulator prra. prra and the sensor kinase prrb are part of a two-component signaling pathway that influences a wide range of processes under oxygen-limited conditions. in this work we characterized the pathway of transcription activation by prrb and prra by purifying these proteins, analyzing them in vitro, and characterizing a mutant prra protein in viv ... | 2002 | 11751815 |
| phylogeny and functional expression of ribulose 1,5-bisphosphate carboxylase/oxygenase from the autotrophic ammonia-oxidizing bacterium nitrosospira sp. isolate 40ki. | the autotrophic ammonia-oxidizing bacteria (aob), which play an important role in the global nitrogen cycle, assimilate co(2) by using ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco). here we describe the first detailed study of rubisco (cbb) genes and proteins from the aob. the cbbls genes from nitrosospira sp. isolate 40ki were cloned and sequenced. partial sequences of the rubisco large subunit (cbbl) from 13 other aob belonging to the beta and gamma subgroups of the class proteobac ... | 2002 | 11751824 |
| transcription factor fnrp from paracoccus denitrificans contains an iron-sulfur cluster and is activated by anoxia: identification of essential cysteine residues. | the paracoccus denitrificans transcription factor fnrp has been characterized using artificial fnr-dependent promoter-lacz fusion plasmids in escherichia coli. fnrp can activate both class i and class ii fnr-dependent promoters in response to anoxia but shows a marked preference for the class ii promoter, where the fnr binding site is centered at -41.5 with respect to the transcription start site. fnrp was found to be inactive in an iscs mutant in vivo, demonstrating a requirement for cysteine d ... | 2002 | 11751828 |
| novel 2,4-dichlorophenoxyacetic acid degradation genes from oligotrophic bradyrhizobium sp. strain hw13 isolated from a pristine environment. | the tfd genes of ralstonia eutropha jmp134 are the only well-characterized set of genes responsible for 2,4-dichlorophenoxyacetic acid (2,4-d) degradation among 2,4-d-degrading bacteria. a new family of 2,4-d degradation genes, cadrabkc, was cloned and characterized from bradyrhizobium sp. strain hw13, a strain that was isolated from a buried hawaiian soil that has never experienced anthropogenic chemicals. the cadr gene was inferred to encode an arac/xyls type of transcriptional regulator from ... | 2002 | 11751829 |
| luteolin and groesl modulate in vitro activity of nodd. | in the early stages of symbiosis between the soil bacterium sinorhizobium meliloti and its leguminous host plant, alfalfa, bacterial nodulation (nod) genes are controlled by nodd1, nodd2, and nodd3, members of the lysr family of transcriptional regulators, in response to flavonoid and other inducers released by alfalfa. to gain an understanding of the biochemical aspects of this action, epitope-tagged recombinant nodd1 and nodd3 were overexpressed in escherichia coli. the dna binding properties ... | 2002 | 11751831 |
| the genome sequence of the facultative intracellular pathogen brucella melitensis. | brucella melitensis is a facultative intracellular bacterial pathogen that causes abortion in goats and sheep and malta fever in humans. the genome of b. melitensis strain 16m was sequenced and found to contain 3,294,935 bp distributed over two circular chromosomes of 2,117,144 bp and 1,177,787 bp encoding 3,197 orfs. by using the bioinformatics suite ergo, 2,487 (78%) orfs were assigned functions. the origins of replication of the two chromosomes are similar to those of other alpha-proteobacter ... | 2002 | 11756688 |