| transcriptomic analysis of rhizobium leguminosarum biovar viciae in symbiosis with host plants pisum sativum and vicia cracca. | rhizobium leguminosarum bv. viciae forms nitrogen-fixing nodules on several legumes, including pea (pisum sativum) and vetch (vicia cracca), and has been widely used as a model to study nodule biochemistry. to understand the complex biochemical and developmental changes undergone by r. leguminosarum bv. viciae during bacteroid development, microarray experiments were first performed with cultured bacteria grown on a variety of carbon substrates (glucose, pyruvate, succinate, inositol, acetate, a ... | 2009 | 19376875 |
| strategies for acquiring the phospholipid metabolite inositol in pathogenic bacteria, fungi and protozoa: making it and taking it. | myo-inositol (inositol) is an essential nutrient that is used for building phosphatidylinositol and its derivatives in eukaryotes and even in some eubacteria such as the mycobacteria. as a consequence, fungal, protozoan and mycobacterial pathogens must be able to acquire inositol in order to proliferate and cause infection in their hosts. there are two primary mechanisms for acquiring inositol. one is to synthesize inositol from glucose 6-phosphate using two sequentially acting enzymes: inositol ... | 2009 | 19383710 |
| an icmf family protein, implm, is an integral inner membrane protein interacting with impkl, and its walker a motif is required for type vi secretion system-mediated hcp secretion in agrobacterium tumefaciens. | an intracellular multiplication f (icmf) family protein is a conserved component of a newly identified type vi secretion system (t6ss) encoded in many animal and plant-associated proteobacteria. we have previously identified impl(m), an icmf family protein that is required for the secretion of the t6ss substrate hemolysin-coregulated protein (hcp) from the plant-pathogenic bacterium agrobacterium tumefaciens. in this study, we characterized the topology of impl(m) and the importance of its nucle ... | 2009 | 19395482 |
| proteomic analysis of the response of the plant growth-promoting bacterium pseudomonas putida uw4 to nickel stress. | plant growth-promoting bacteria can alleviate the inhibitory effects of various heavy metals on plant growth, via decreasing levels of stress-induced ethylene. however, little has been done to detect any mechanisms specific for heavy metal resistance of this kind of bacteria. here, we investigate the response of the wild-type plant growth-promoting bacterium pseudomonas putida uw4 to nickel stress using proteomic approaches. the mutant strain p. putida uw4/acds-, lacking a functional 1-aminocycl ... | 2009 | 19422705 |
| the sinorhizobium meliloti lpxxl and acpxl proteins play important roles in bacteroid development within alfalfa. | free-living sinorhizobium meliloti lpxxl and acpxl mutants lack lipid a very-long-chain fatty acids (vlcfas) and have reduced competitiveness in alfalfa. we demonstrate that lpxxl and acpxl play important but distinct roles in bacteroid development and that lpxxl is essential for the modification of s. meliloti bacteroid lipid a with vlcfas. | 2009 | 19429615 |
| genome degradation in brucella ovis corresponds with narrowing of its host range and tissue tropism. | brucella ovis is a veterinary pathogen associated with epididymitis in sheep. despite its genetic similarity to the zoonotic pathogens b. abortus, b. melitensis and b. suis, b. ovis does not cause zoonotic disease. genomic analysis of the type strain atcc25840 revealed a high percentage of pseudogenes and increased numbers of transposable elements compared to the zoonotic brucella species, suggesting that genome degradation has occurred concomitant with narrowing of the host range of b. ovis. th ... | 2009 | 19436743 |
| bacterial associates of arboreal ants and their putative functions in an obligate ant-plant mutualism. | bacterial communities are highly diverse and have great ecological importance. in the present study, we used an in silico analysis of terminal restriction fragments (trf) to characterize the bacterial community of the plant ant pseudomyrmex ferrugineus. this species is an obligate inhabitant of acacia myrmecophytes and feeds exclusively on plant-derived food sources. ants are the dominant insect group in tropical rain forests. associations of ants with microbes, which contribute particularly to ... | 2009 | 19447959 |
| rhizobium leguminosarum biovar viciae 3841, deficient in 27-hydroxyoctacosanoate-modified lipopolysaccharide, is impaired in desiccation tolerance, biofilm formation and motility. | the lipopolysaccharide (lps) of the gram-negative legume symbiont rhizobium leguminosarum biovar viciae 3,841 contains several unique modifications, including the addition of a 27-hydroxyoctacosanoic acid (27ohc28 : 0), also termed the very long chain fatty acid (vlcfa), attached at the 2' position of lipid a. a transposon mutant that lacks expression of two putative 3-oxo-acyl [acyl-carrier protein] synthase ii genes, fabf1 and fabf2, from the vlcfa biosynthetic cluster, was isolated and charac ... | 2009 | 19460825 |
| the genome sequence of geobacter metallireducens: features of metabolism, physiology and regulation common and dissimilar to geobacter sulfurreducens. | the genome sequence of geobacter metallireducens is the second to be completed from the metal-respiring genus geobacter, and is compared in this report to that of geobacter sulfurreducens in order to understand their metabolic, physiological and regulatory similarities and differences. | 2009 | 19473543 |
| the manganese transporter mnth is a critical virulence determinant for brucella abortus 2308 in experimentally infected mice. | the gene designated bab1_1460 in the brucella abortus 2308 genome sequence is predicted to encode the manganese transporter mnth. phenotypic analysis of an isogenic mnth mutant indicates that mnth is the sole high-affinity manganese transporter in this bacterium but that mnth does not play a detectable role in the transport of fe(2+), zn(2+), co(2+), or ni(2+). consistent with the apparent selectivity of the corresponding gene product, the expression of the mnth gene in b. abortus 2308 is repres ... | 2009 | 19487482 |
| quorum sensing differentially regulates pseudomonas aeruginosa type vi secretion locus i and homologous loci ii and iii, which are required for pathogenesis. | pseudomonas aeruginosa harbours three type vi secretion (t6s) loci. although hsi-i has been partially studied, limited knowledge is available on the homologous loci hsi-ii and hsi-iii. we show that quorum sensing (qs) differentially regulates the expression of genes at all three loci. hsi-i-associated gene expression is suppressed by both the homoserine lactone transcription factor lasr and the 4-hydroxy-2-alkylquinoline (haq) transcriptional regulator mvfr. conversely, both hsi-ii and hsi-iii l ... | 2009 | 19497948 |
| an alternative succinate (2-oxoglutarate) transport system in rhizobium tropici is induced in nodules of phaseolus vulgaris. | the rhizobial dcta permease is essential for the development of effective nitrogen-fixing bacteroids, which was correlated with its requirement for growth on c(4)-dicarboxylates. a previously described dcta mutant of rhizobium tropici ciat899, strain ga1 (dcta), however, was unexpectedly still able to grow on succinate as a sole carbon source but less efficiently than ciat899. like other rhizobial dcta mutants, ga1 was unable to grow on fumarate or malate as a carbon source and induced the forma ... | 2009 | 19502401 |
| functional and expression analyses of the cop operon, required for copper resistance in agrobacterium tumefaciens. | the copper resistance determinant coparz, which encodes a cpx-type copper atpase efflux protein, a transcriptional regulator, and a putative intracellular copper chaperone, was functionally characterized for the phytopathogenic bacterium agrobacterium tumefaciens. these genes are transcribed as an operon, and their expression is induced in response to increasing copper and silver ion concentrations in a copr-dependent fashion. analysis of the coparz promoter revealed a putative copr binding box ... | 2009 | 19502402 |
| fur controls iron homeostasis and oxidative stress defense in the oligotrophic alpha-proteobacterium caulobacter crescentus. | in most bacteria, the ferric uptake regulator (fur) is a global regulator that controls iron homeostasis and other cellular processes, such as oxidative stress defense. in this work, we apply a combination of bioinformatics, in vitro and in vivo assays to identify the caulobacter crescentus fur regulon. a c. crescentus fur deletion mutant showed a slow growth phenotype, and was hypersensitive to h(2)o(2) and organic peroxide. using a position weight matrix approach, several predicted fur-binding ... | 2009 | 19520766 |
| ppor is a conserved unpaired luxr solo of pseudomonas putida which binds n-acyl homoserine lactones. | only a small number of pseudomonas putida strains possess the typical n-acyl homoserine lactone quorum sensing system (ahl qs) that consists of a modular luxr family protein and its cognate luxi homolog that produces the ahl signal. moreover, ahl qs systems in p. putida strains are diverse in the type of ahls they produce and the phenotypes that they regulate. | 2009 | 19534812 |
| waaa of the hyperthermophilic bacterium aquifex aeolicus is a monofunctional 3-deoxy-d-manno-oct-2-ulosonic acid transferase involved in lipopolysaccharide biosynthesis. | the hyperthermophile aquifex aeolicus belongs to the deepest branch in the bacterial genealogy. although it has long been recognized that this unique gram-negative bacterium carries genes for different steps of lipopolysaccharide (lps) formation, data on the lps itself or detailed knowledge of the lps pathway beyond the first committed steps of lipid a and 3-deoxy-d-manno-oct-2-ulosonic acid (kdo) synthesis are still lacking. we now report the functional characterization of the thermostable kdo ... | 2009 | 19546212 |
| human toll-like receptor 4 responses to p. gingivalis are regulated by lipid a 1- and 4'-phosphatase activities. | signal transduction following binding of lipopolysaccharide (lps) to toll-like receptor 4 (tlr4) is an essential aspect of host innate immune responses to infection by gram-negative pathogens. here, we describe a novel molecular mechanism used by a prevalent human bacterial pathogen to evade and subvert the human innate immune system. we show that the oral pathogen, porphyromonas gingivalis, uses endogenous lipid a 1- and 4'-phosphatase activities to modify its lps, creating immunologically sile ... | 2009 | 19552698 |
| rhizobium mesosinicum sp. nov., isolated from root nodules of three different legumes. | thirteen novel strains were isolated from root nodules of three different leguminous plants of the genera albizia, kummerowia and dalbergia grown in china. cells of these strains were gram-negative, strictly aerobic, non-spore-forming, motile rods. phylogenetic analysis of 16s rrna gene sequences revealed that they belong to the genus rhizobium. a representative strain, ccbau 25010t, showed 98.8% 16s rrna gene sequence similarity to its closest phylogenetic relative, rhizobium sullae is123t. the ... | 2009 | 19567587 |
| the complete genome of teredinibacter turnerae t7901: an intracellular endosymbiont of marine wood-boring bivalves (shipworms). | here we report the complete genome sequence of teredinibacter turnerae t7901. t. turnerae is a marine gamma proteobacterium that occurs as an intracellular endosymbiont in the gills of wood-boring marine bivalves of the family teredinidae (shipworms). this species is the sole cultivated member of an endosymbiotic consortium thought to provide the host with enzymes, including cellulases and nitrogenase, critical for digestion of wood and supplementation of the host's nitrogen-deficient diet. t. t ... | 2009 | 19568419 |
| the electron transfer system of syntrophically grown desulfovibrio vulgaris. | interspecies hydrogen transfer between organisms producing and consuming hydrogen promotes the decomposition of organic matter in most anoxic environments. although syntrophic coupling between hydrogen producers and consumers is a major feature of the carbon cycle, mechanisms for energy recovery at the extremely low free energies of reactions typical of these anaerobic communities have not been established. in this study, comparative transcriptional analysis of a model sulfate-reducing microbe, ... | 2009 | 19581361 |
| characterization of the dicarboxylate transporter dcta in corynebacterium glutamicum. | transporters of the dicarboxylate amino acid-cation symporter family often mediate uptake of c(4)-dicarboxylates, such as succinate or l-malate, in bacteria. a member of this family, dicarboxylate transporter a (dcta) from corynebacterium glutamicum, was characterized to catalyze uptake of the c(4)-dicarboxylates succinate, fumarate, and l-malate, which was inhibited by oxaloacetate, 2-oxoglutarate, and glyoxylate. dcta activity was not affected by sodium availability but was dependent on the el ... | 2009 | 19581365 |
| (homo)glutathione depletion modulates host gene expression during the symbiotic interaction between medicago truncatula and sinorhizobium meliloti. | under nitrogen-limiting conditions, legumes interact with symbiotic rhizobia to produce nitrogen-fixing root nodules. we have previously shown that glutathione and homoglutathione [(h)gsh] deficiencies impaired medicago truncatula symbiosis efficiency, showing the importance of the low m(r) thiols during the nodulation process in the model legume m. truncatula. in this study, the plant transcriptomic response to sinorhizobium meliloti infection under (h)gsh depletion was investigated using cdna- ... | 2009 | 19587096 |
| multiple copies of rosr and pssa genes enhance exopolysaccharide production, symbiotic competitiveness and clover nodulation in rhizobium leguminosarum bv. trifolii. | rhizobium leguminosarum bv. trifolii exopolysaccharide (eps) plays an important role in determining symbiotic competence. the pssa gene encoding the first glucosyl-ip-transferase and rosr encoding a positive transcriptional regulator are key genes involved in the biosynthesis and regulation of eps production. mutation in pssa resulted in deficiency in eps production and rosr mutation substantially decreased the amount of eps. both mutants induced nodules but the bacteria were unable to fix nitro ... | 2009 | 19588265 |
| legumes regulate rhizobium bacteroid development and persistence by the supply of branched-chain amino acids. | one of the largest contributions to biologically available nitrogen comes from the reduction of n(2) to ammonia by rhizobia in symbiosis with legumes. plants supply dicarboxylic acids as a carbon source to bacteroids, and in return they receive ammonia. however, metabolic exchange must be more complex, because effective n(2) fixation by rhizobium leguminosarum bv viciae bacteroids requires either one of two broad-specificity amino acid abc transporters (aap and bra). it was proposed that amino a ... | 2009 | 19597156 |
| the analysis of core and symbiotic genes of rhizobia nodulating vicia from different continents reveals their common phylogenetic origin and suggests the distribution of rhizobium leguminosarum strains together with vicia seeds. | in this work, we analysed the core and symbiotic genes of rhizobial strains isolated from vicia sativa in three soils from the northwest of spain, and compared them with other vicia endosymbionts isolated in other geographical locations. the analysis of rrs, reca and atpd genes and 16s-23s rrna intergenic spacer showed that the spanish strains nodulating v. sativa are phylogenetically close to those isolated from v. sativa and v. faba in different european, american and asian countries forming a ... | 2009 | 19603151 |
| crystal structure and acyl chain selectivity of escherichia coli lpxd, the n-acyltransferase of lipid a biosynthesis. | lpxd catalyzes the third step of lipid a biosynthesis, the r-3-hydroxyacyl-acp-dependent n-acylation of udp-3-o-(acyl)-alpha-d-glucosamine, and is a target for new antibiotic development. here we report the 2.6 a crystal structure of the escherichia coli lpxd homotrimer (eclpxd). as is the case in chlamydia trachomatis lpxd (ctlxpd), each eclpxd chain consists of an n-terminal uridine-binding region, a left-handed parallel beta-helix (lbetah), and a c-terminal alpha-helical domain. the backbones ... | 2009 | 19655786 |
| genotypic and phenotypic characterization of rhizobia that nodulate snap bean (phaseolus vulgaris l.) in egyptian soils. | snap bean fields in 12 of the 25 governorates of egypt were surveyed to determine the distribution and taxonomy of snap bean-nodulating rhizobia. nodulation rates in the field were very low, indicating that egyptian soils do not have sufficient numbers of snap bean-compatible rhizobium spp. a total of 87 rhizobial isolates were assayed on the most commonly grown cultivars in order to identify the most effective strains. the five most effective isolates (r11, r13, r28, r49 and r52) were fast-grow ... | 2009 | 19682816 |
| quorum sensing regulation of the two hcp alleles in vibrio cholerae o1 strains. | the type vi secretion system (t6ss) has emerged as a protein secretion system important to several gram-negative bacterial species. one of the common components of the system is hcp, initially described as a hemolysin co-regulated protein in a serotype o17 strain of vibrio cholerae. homologs to v. cholerae hcp genes have been found in all characterized type vi secretion systems and they are present also in the serotype o1 strains of v. cholerae that are the cause of cholera diseases but seemed t ... | 2009 | 19701456 |
| a draft genome sequence and functional screen reveals the repertoire of type iii secreted proteins of pseudomonas syringae pathovar tabaci 11528. | pseudomonas syringae is a widespread bacterial pathogen that causes disease on a broad range of economically important plant species. pathogenicity of p. syringae strains is dependent on the type iii secretion system, which secretes a suite of up to about thirty virulence 'effector' proteins into the host cytoplasm where they subvert the eukaryotic cell physiology and disrupt host defences. p. syringae pathovar tabaci naturally causes disease on wild tobacco, the model member of the solanaceae, ... | 2009 | 19703286 |
| proline antagonizes gaba-induced quenching of quorum-sensing in agrobacterium tumefaciens. | plants accumulate free l-proline (pro) in response to abiotic stresses (drought and salinity) and presence of bacterial pathogens, including the tumor-inducing bacterium agrobacterium tumefaciens. however, the function of pro accumulation in host-pathogen interaction is still unclear. here, we demonstrated that pro antagonizes plant gaba-defense in the a. tumefaciens c58-induced tumor by interfering with the import of gaba and consequently the gaba-induced degradation of the bacterial quorum-sen ... | 2009 | 19706545 |
| different species and symbiotic genotypes of field rhizobia can nodulate phaseolus vulgaris in tunisian soils. | abstract a collection of 160 isolates of rhizobia nodulating phaseolus vulgaris in three geographical regions in tunisia was characterized by restriction fragment length polymorphism analysis of polymerase chain reaction (pcr)-amplified 16s rdna, nifh and nodc genes. nine groups of rhizobia were delineated: rhizobium gallicum biovar (bv.) gallicum, rhizobium leguminosarum bv. phaseoli and bv. viciae, rhizobium etli bv. phaseoli, rhizobium giardinii bv. giardinii, and four groups related to speci ... | 2002 | 19709241 |
| identification and analysis of rhizobial plasmid origins of transfer. | twelve rhizobium leguminosarum isolates from france, germany and the uk, each carrying between four and seven plasmids, were screened by pcr using primers designed to amplify partial traa and trac genes and the intergenic spacer (igs) between them, which is expected to contain orit (the nick site for conjugal transfer). five strains, 1062, res-2, res-6, res-7 and res-9, generated orit-containing pcr fragments. sequencing identified three types that are related to but different from other rhizobi ... | 2002 | 19709282 |
| evaluation of a yersinia pestis mutant impaired in a thermoregulated type vi-like secretion system in flea, macrophage and murine models. | type vi secretion systems (t6sss) have been identified recently in several gram-negative organisms and have been shown to be associated with virulence in some bacterial pathogens. a t6ss of yersinia pestis co92 (locus ypo0499-ypo0516) was deleted followed by investigation of the phenotype of this mutation. we observed that this t6ss locus of y. pestis was preferentially expressed at 26 degrees c in comparison to 37 degrees c suggesting a possible role in the flea cycle. however, we found that th ... | 2009 | 19716410 |
| post-transcriptional regulation of nifa expression by hfq and rnase e complex in rhizobium leguminosarum bv. viciae. | nifa is the general transcriptional activator of nitrogen fixation genes in diazotrophic bacteria. in rhizobium leguminosarum bv. viciae strain 8401/prl1ji, the nifa gene is part of a gene cluster (fixabcxnifab). in this study, results showed that in r. leguminosarum bv.viciae 8401/prl1ji, host factor required (hfq), and rnase e were involved in the post-transcriptional regulation of nifa expression. it was found that hfq-dependent rnase e cleavage of nifa mrna was essential for nifa translation ... | 2009 | 19727520 |
| n- and c-terminal regions of the quorum-sensing activator trar cooperate in interactions with the alpha and sigma-70 components of rna polymerase. | positive control (pc) mutants defining 20 residues of the quorum-sensing activator trar were isolated that bind dna but show defects in activating transcription from class i, class ii or both types of promoters. these pc residues, located in both the n- and c-terminal regions, combine to form three patches, one on the top (ii) and two near the dna binding domain on both lateral faces of the dimer (i and iii). patches i and ii, but not patch iii, involve residues from both protomers and are essen ... | 2009 | 19732344 |
| plant-associated bacterial degradation of toxic organic compounds in soil. | a number of toxic synthetic organic compounds can contaminate environmental soil through either local (e.g., industrial) or diffuse (e.g., agricultural) contamination. increased levels of these toxic organic compounds in the environment have been associated with human health risks including cancer. plant-associated bacteria, such as endophytic bacteria (non-pathogenic bacteria that occur naturally in plants) and rhizospheric bacteria (bacteria that live on and near the roots of plants), have bee ... | 2009 | 19742157 |
| identification of functional lsrb-like autoinducer-2 receptors. | although a variety of bacterial species have been reported to use the interspecies communication signal autoinducer-2 (ai-2) to regulate multiple behaviors, the molecular mechanisms of ai-2 recognition and signal transduction remain poorly understood. to date, two types of ai-2 receptors have been identified: luxp, present in vibrio spp., and lsrb, first identified in salmonella enterica serovar typhimurium. in s. typhimurium, lsrb is the ligand binding protein of a transport system that enables ... | 2009 | 19749048 |
| identification of direct transcriptional target genes of exos/chvi two-component signaling in sinorhizobium meliloti. | the sinorhizobium meliloti exos/chvi two-component signaling pathway is required for the development of a nitrogen-fixing symbiosis between s. meliloti and its plant hosts. exos/chvi also has important roles in regulating succinoglycan production, biofilm formation, motility, nutrient utilization, and the viability of free-living bacteria. previous microarray experiments with an exos96::tn5 mutant indicated that exos/chvi influences the expression of a few hundred genes, complicating the investi ... | 2009 | 19749054 |
| diminished exoproteome of frankia spp. in culture and symbiosis. | frankia species are the most geographically widespread gram-positive plant symbionts, carrying out n(2) fixation in root nodules of trees and woody shrubs called actinorhizal plants. taking advantage of the sequencing of three frankia genomes, proteomics techniques were used to investigate the population of extracellular proteins (the exoproteome) from frankia, some of which potentially mediate host-microbe interactions. initial two-dimensional sodium dodecyl sulfate-polyacrylamide gel electroph ... | 2009 | 19749056 |
| the impact of window functions on nmr-based paramagnetic relaxation enhancement measurements in membrane proteins. | though challenging, solution nmr spectroscopy allows fundamental interrogation of the structure and dynamics of membrane proteins. one major technical hurdle in studies of helical membrane proteins by nmr is the difficulty of obtaining sufficient long range noes to determine tertiary structure. for this reason, long range distance information is sometimes sought through measurement of paramagnetic relaxation enhancements (pre) of nmr nuclei as a function of distance from an introduced paramagnet ... | 2010 | 19751702 |
| the impact of window functions on nmr-based paramagnetic relaxation enhancement measurements in membrane proteins. | though challenging, solution nmr spectroscopy allows fundamental interrogation of the structure and dynamics of membrane proteins. one major technical hurdle in studies of helical membrane proteins by nmr is the difficulty of obtaining sufficient long range noes to determine tertiary structure. for this reason, long range distance information is sometimes sought through measurement of paramagnetic relaxation enhancements (pre) of nmr nuclei as a function of distance from an introduced paramagnet ... | 2010 | 19751702 |
| comparison of media used to evaluate rhizobium leguminosarum bivar viciae for phosphate-solubilizing ability. | rhizobium leguminosarum is well known for its ability to fix nitrogen (n). in addition, its capacity to solubilize phosphate (ph) has been receiving attention in recent years. our ultimate objective was to select a r. leguminosarum bv. viciae isolate with superior ph-solubilizing ability. the first step was to identify a culture medium that is sensitive and effective in identifying the ability of r. leguminosarum bv. viciae isolates to solubilize ph. thirty isolates were evaluated for ph solubil ... | 2009 | 19767866 |
| enzymatic tailoring of ornithine in the biosynthesis of the rhizobium cyclic trihydroxamate siderophore vicibactin. | to acquire iron, the n(2)-fixing, symbiotic bacterium rhizobium sp. produce the cyclic trihydroxamate siderophore vicibactin, containing a 30-membered trilactone scaffold. herein we report the overproduction and purification of the six proteins vbsacgols in the bacterial host escherichia coli and the reconstitution of the biosynthesis of vicibactin from primary metabolites. the flavoprotein vbso acts as a pathway-initiating l-ornithine n(5)-hydroxylase, followed by vbsa, which transfers (r)-3-hy ... | 2009 | 19778043 |
| a small functional intramolecular region of nodd was identified by mutation. | in rhizobium leguminosarum bv. viciae, nodd, as a member of the lysr-type transcriptional regulators (lttrs), exerts auto-regulation and activates transcription of other nod genes in the presence of naringenin. lttrs were typically composed of n-terminal dna-binding domain and c-terminal regulatory domain. in this study, by systematic insertion mutation, a region of 12 amino acids in length of nodd was identified as functional domain. insertion mutants in this region appeared to acquire the abil ... | 2009 | 19779647 |
| the low-molecular-weight fraction of exopolysaccharide ii from sinorhizobium meliloti is a crucial determinant of biofilm formation. | sinorhizobium meliloti is a soil bacterium that elicits the formation of root organs called nodules on its host plant, medicago sativa. inside these structures, the bacteria are able to convert atmospheric nitrogen into ammonia, which is then used by the plant as a nitrogen source. the synthesis by s. meliloti of at least one exopolysaccharide, succinoglycan or eps ii, is essential for a successful symbiosis. while exopolysaccharide-deficient mutants induce the formation of nodules, they fail to ... | 2009 | 19783627 |
| bioactive and structural metabolites of pseudomonas and burkholderia species causal agents of cultivated mushrooms diseases. | pseudomonas tolaasii, p. reactans and burkholderia gladioli pv. agaricicola, are responsible of diseases on some species of cultivated mushrooms. the main bioactive metabolites produced by both pseudomonas strains are the lipodepsipeptides (ldps) tolaasin i and ii and the so called white line inducing principle (wlip), respectively, ldps which have been extensively studied for their role in the disease process and for their biological properties. in particular, their antimicrobial activity and t ... | 2008 | 19787100 |
| importance of trehalose biosynthesis for sinorhizobium meliloti osmotolerance and nodulation of alfalfa roots. | the disaccharide trehalose is a well-known osmoprotectant, and trehalose accumulation through de novo biosynthesis is a common response of bacteria to abiotic stress. in this study, we have investigated the role of endogenous trehalose synthesis in the osmotolerance of sinorhizobium meliloti. genes coding for three possible trehalose synthesis pathways are present in the genome of s. meliloti 1021: otsa, treyz, and tres. among these, otsa has a major role in trehalose accumulation under all of t ... | 2009 | 19837796 |
| pantothenate kinase from the thermoacidophilic archaeon picrophilus torridus. | pantothenate kinase (coaa) catalyzes the first step of the coenzyme a (coa) biosynthetic pathway and controls the intracellular concentrations of coa through feedback inhibition in bacteria. an alternative enzyme found in archaea, pantoate kinase, is missing in the order thermoplasmatales. the pto0232 gene from picrophilus torridus, a thermoacidophilic euryarchaeon, is shown to be a distant homologue of the prokaryotic type i coaa. the cloned gene clearly complements the poor growth of the tempe ... | 2010 | 19854913 |
| pantothenate kinase from the thermoacidophilic archaeon picrophilus torridus. | pantothenate kinase (coaa) catalyzes the first step of the coenzyme a (coa) biosynthetic pathway and controls the intracellular concentrations of coa through feedback inhibition in bacteria. an alternative enzyme found in archaea, pantoate kinase, is missing in the order thermoplasmatales. the pto0232 gene from picrophilus torridus, a thermoacidophilic euryarchaeon, is shown to be a distant homologue of the prokaryotic type i coaa. the cloned gene clearly complements the poor growth of the tempe ... | 2010 | 19854913 |
| a study in entire chromosomes of violations of the intra-strand parity of complementary nucleotides (chargaff's second parity rule). | chargaff's rule of intra-strand parity (isp) between complementary mono/oligonucleotides in chromosomes is well established in the scientific literature. although a large numbers of papers have been published citing works and discussions on isp in the genomic era, scientists are yet to find all the factors responsible for such a universal phenomenon in the chromosomes. in the present work, we have tried to address the issue from a new perspective, which is a parallel feature to isp. the composit ... | 2009 | 19861381 |
| mechanisms and regulation of polar surface attachment in agrobacterium tumefaciens. | agrobacterium tumefaciens is a plant pathogen that transfers a segment of its own dna into host plants to cause crown gall disease. the infection process requires intimate contact between the infecting bacteria and the host tissue. a. tumefaciens attaches efficiently to plant tissues and to abiotic surfaces, and can establish complex biofilms at colonization sites. the dominant mode of attachment is via a single pole in contact with the surface. several different appendages, adhesins and adhesiv ... | 2009 | 19879182 |
| plasmid transfer systems in the rhizobia. | rhizobia are agriculturally important bacteria that can form nitrogen-fixing nodules on the roots of leguminous plants. agricultural application of rhizobial inoculants can play an important role in increasing leguminous crop yields. in temperate rhizobia, genes involved in nodulation and nitrogen fixation are usually located on one or more large plasmids (psyms) or on symbiotic islands. in addition, other large plasmids of rhizobia carry genes that are beneficial for survival and competition of ... | 2009 | 19898531 |
| complete reconstitution of a highly reducing iterative polyketide synthase. | highly reducing iterative polyketide synthases are large, multifunctional enzymes that make important metabolites in fungi, such as lovastatin, a cholesterol-lowering drug from aspergillus terreus. we report efficient expression of the lovastatin nonaketide synthase (lovb) from an engineered strain of saccharomyces cerevisiae, as well as complete reconstitution of its catalytic function in the presence and absence of cofactors (the reduced form of nicotinamide adenine dinucleotide phosphate and ... | 2009 | 19900898 |
| the properties of nodd were affected by mere variation in length within its hinge region. | in rhizobium leguminosarum bv. viciae, nodd, a member of the lysr-type transcriptional regulators, while auto-regulating, activates transcription of other nod genes in the presence of naringenin. a hinge region of nodd was previously identified in our laboratory as a functional region independent of its n-terminal dna-binding and c-terminal regulatory domain. further study was carried out to see the possible effect of the length variation in the hinge region on nodd properties. to our surprise, ... | 2009 | 19902131 |
| how does sulphur availability modify n acquisition of white clover (trifolium repens l.)? | the role of s in legume growth, n uptake, and n2 fixation was investigated using white clover (trifolium repens l.) as a model species. we examined whether the effect of sulphate addition on n fixation resulted from a stimulation of host plant growth, a specific effect of s on nodulation, or a specific effect of s on nodule metabolism. clones of white clover, inoculated with rhizobium leguminosarum, were grown for 140 d in a hydroponic system with three levels of sulphate concentration (0 mm, 0. ... | 2010 | 19933318 |
| how does sulphur availability modify n acquisition of white clover (trifolium repens l.)? | the role of s in legume growth, n uptake, and n2 fixation was investigated using white clover (trifolium repens l.) as a model species. we examined whether the effect of sulphate addition on n fixation resulted from a stimulation of host plant growth, a specific effect of s on nodulation, or a specific effect of s on nodule metabolism. clones of white clover, inoculated with rhizobium leguminosarum, were grown for 140 d in a hydroponic system with three levels of sulphate concentration (0 mm, 0. ... | 2010 | 19933318 |
| phenotypic, genotypic, and symbiotic diversities in strains nodulating clover in different soils in spain. | trifolium species are the most common legumes present in wild spanish soils; however, there are no studies to date on the diversity of rhizobia nodulating clover in spain. twenty strains from different spanish soils with acidic, neutral, and basic ph were selected to study their genotypic, phenotypic, and symbiotic features. the results showed that the isolates were genotypically diverse, displaying 12 different dna fingerprint patterns and also 14 different plasmid profiles. although they have ... | 2009 | 19935893 |
| [chemotaxis of rhizobium leguminosarum bv. viciae to organic substances]. | the chemotaxis of nodule bacteria cultures of pea rhizobium leguminosarum bv. vicia rrl1, rrl3, rrl6 i rrl7 isolated from the plants of ivano-frankivsk district to different organic substances was investigated. saccharose, pyruvate and tartaric acid were the most active attractants among carbohydrates and organic acids studied for all used nodule bacteria strains. serine, alanine, glycine, tyrosine and cysteine were the most active attractants of amino acids. dependence of pea nodule bacteria ch ... | 2009 | 19938606 |
| distribution of cepacian biosynthesis genes among environmental and clinical burkholderia strains and role of cepacian exopolysaccharide in resistance to stress conditions. | the genus burkholderia includes strains pathogenic to animals and plants, bioremediators, or plant growth promoters. genome sequence analyses of representative burkholderia cepacia complex (bcc) and non-bcc strains for the presence of the bce-i gene cluster, directing the biosynthesis of the exopolysaccharide (eps) cepacian, further extended this previously described cluster by another 9 genes. the genes in the bce-ii cluster were named bcem to bceu and encode products putatively involved in nuc ... | 2010 | 19948863 |
| distribution of cepacian biosynthesis genes among environmental and clinical burkholderia strains and role of cepacian exopolysaccharide in resistance to stress conditions. | the genus burkholderia includes strains pathogenic to animals and plants, bioremediators, or plant growth promoters. genome sequence analyses of representative burkholderia cepacia complex (bcc) and non-bcc strains for the presence of the bce-i gene cluster, directing the biosynthesis of the exopolysaccharide (eps) cepacian, further extended this previously described cluster by another 9 genes. the genes in the bce-ii cluster were named bcem to bceu and encode products putatively involved in nuc ... | 2010 | 19948863 |
| characterization of a gene family of outer membrane proteins (ropb) in rhizobium leguminosarum bv. viciae vf39sm and the role of the sensor kinase chvg in their regulation. | the outer membrane of gram-negative bacteria represents the interface between the bacterium and its external environment. it has a critical role as a protective barrier against harmful substances and is also important in host-bacteria interactions representing the initial physical point of contact between the host cell and bacterial cell. ropb is a previously identified outer membrane protein from rhizobium leguminosarum bv. viciae that is present in free-living cells but absent in bacteroids (h ... | 2010 | 20023026 |
| characterization of a gene family of outer membrane proteins (ropb) in rhizobium leguminosarum bv. viciae vf39sm and the role of the sensor kinase chvg in their regulation. | the outer membrane of gram-negative bacteria represents the interface between the bacterium and its external environment. it has a critical role as a protective barrier against harmful substances and is also important in host-bacteria interactions representing the initial physical point of contact between the host cell and bacterial cell. ropb is a previously identified outer membrane protein from rhizobium leguminosarum bv. viciae that is present in free-living cells but absent in bacteroids (h ... | 2010 | 20023026 |
| rhizobium leguminosarum hupe encodes a nickel transporter required for hydrogenase activity. | synthesis of the hydrogen uptake (hup) system in rhizobium leguminosarum bv. viciae requires the function of an 18-gene cluster (hupslcdefghijk-hypabfcdex). among them, the hupe gene encodes a protein showing six transmembrane domains for which a potential role as a nickel permease has been proposed. in this paper, we further characterize the nickel transport capacity of hupe and that of the translated product of hupe2, a hydrogenase-unlinked gene identified in the r. leguminosarum genome. hupe2 ... | 2010 | 20023036 |
| rhizobium leguminosarum hupe encodes a nickel transporter required for hydrogenase activity. | synthesis of the hydrogen uptake (hup) system in rhizobium leguminosarum bv. viciae requires the function of an 18-gene cluster (hupslcdefghijk-hypabfcdex). among them, the hupe gene encodes a protein showing six transmembrane domains for which a potential role as a nickel permease has been proposed. in this paper, we further characterize the nickel transport capacity of hupe and that of the translated product of hupe2, a hydrogenase-unlinked gene identified in the r. leguminosarum genome. hupe2 ... | 2010 | 20023036 |
| functional role of bradyrhizobium japonicum trehalose biosynthesis and metabolism genes during physiological stress and nodulation. | trehalose, a disaccharide accumulated by many microorganisms, acts as a protectant during periods of physiological stress, such as salinity and desiccation. previous studies reported that the trehalose biosynthetic genes (otsa, tres, and trey) in bradyrhizobium japonicum were induced by salinity and desiccation stresses. functional mutational analyses indicated that disruption of otsa decreased trehalose accumulation in cells and that an otsa trey double mutant accumulated an extremely low level ... | 2010 | 20023090 |
| functional role of bradyrhizobium japonicum trehalose biosynthesis and metabolism genes during physiological stress and nodulation. | trehalose, a disaccharide accumulated by many microorganisms, acts as a protectant during periods of physiological stress, such as salinity and desiccation. previous studies reported that the trehalose biosynthetic genes (otsa, tres, and trey) in bradyrhizobium japonicum were induced by salinity and desiccation stresses. functional mutational analyses indicated that disruption of otsa decreased trehalose accumulation in cells and that an otsa trey double mutant accumulated an extremely low level ... | 2010 | 20023090 |
| identification of a novel abc transporter required for desiccation tolerance, and biofilm formation in rhizobium leguminosarum bv. viciae 3841. | rhizobium leguminosarum is a soil bacterium with the ability to form nitrogen-fixing nodules on the roots of leguminous plants. soil-dwelling, free-living r. leguminosarum often encounters desiccation stress, which impacts its survival within the soil. the mechanisms by which soil bacteria resist the effects of desiccation stress have been described. however, the role of the cell envelope in the desiccation tolerance mechanisms of rhizobia is relatively uncharacterized. using a transposon mutage ... | 2010 | 20030718 |
| identification of a novel abc transporter required for desiccation tolerance, and biofilm formation in rhizobium leguminosarum bv. viciae 3841. | rhizobium leguminosarum is a soil bacterium with the ability to form nitrogen-fixing nodules on the roots of leguminous plants. soil-dwelling, free-living r. leguminosarum often encounters desiccation stress, which impacts its survival within the soil. the mechanisms by which soil bacteria resist the effects of desiccation stress have been described. however, the role of the cell envelope in the desiccation tolerance mechanisms of rhizobia is relatively uncharacterized. using a transposon mutage ... | 2010 | 20030718 |
| multidrug efflux pump mdtbc of escherichia coli is active only as a b2c heterotrimer. | rnd (resistance-nodulation-division) family transporters in gram-negative bacteria frequently pump out a wide range of inhibitors and often contribute to multidrug resistance to antibiotics and biocides. an archetypal rnd pump of escherichia coli, acrb, is known to exist as a homotrimer, and this construction is essential for drug pumping through the functionally rotating mechanism. mdtbc, however, appears different because two pump genes coexist within a single operon, and genetic deletion data ... | 2010 | 20038594 |
| multidrug efflux pump mdtbc of escherichia coli is active only as a b2c heterotrimer. | rnd (resistance-nodulation-division) family transporters in gram-negative bacteria frequently pump out a wide range of inhibitors and often contribute to multidrug resistance to antibiotics and biocides. an archetypal rnd pump of escherichia coli, acrb, is known to exist as a homotrimer, and this construction is essential for drug pumping through the functionally rotating mechanism. mdtbc, however, appears different because two pump genes coexist within a single operon, and genetic deletion data ... | 2010 | 20038594 |
| complete genome sequence of the fire blight pathogen erwinia pyrifoliae dsm 12163t and comparative genomic insights into plant pathogenicity. | erwinia pyrifoliae is a newly described necrotrophic pathogen, which causes fire blight on asian (nashi) pear and is geographically restricted to eastern asia. relatively little is known about its genetics compared to the closely related main fire blight pathogen e. amylovora. | 2010 | 20047678 |
| the helicobacter pylori groes cochaperonin hspa functions as a specialized nickel chaperone and sequestration protein through its unique c-terminal extension. | the transition metal nickel plays a central role in the human gastric pathogen helicobacter pylori because it is required for two enzymes indispensable for colonization, the nickel metalloenzyme urease and [nife] hydrogenase. to sustain nickel availability for these metalloenzymes while providing protection from the metal's harmful effects, h. pylori is equipped with several specific nickel-binding proteins. among these, h. pylori possesses a particular chaperone, hspa, that is a homolog of the ... | 2010 | 20061471 |
| identification and functional analysis of type iii effector proteins in mesorhizobium loti. | mesorhizobium loti maff303099, a microsymbiont of the model legume lotus japonicus, possesses a cluster of genes (tts) that encode a type iii secretion system (t3ss). in the presence of heterologous nodd from rhizobium leguminosarum and a flavonoid naringenin, we observed elevated expression of the tts genes and secretion of several proteins into the culture medium. inoculation experiments with wild-type and t3ss mutant strains revealed that the presence of the t3ss affected nodulation at a spec ... | 2010 | 20064065 |
| phenotypic and genetic diversity in sinorhizobium meliloti and s. medicae from drought and salt affected regions of morocco. | sinorhizobium meliloti and s. medicae are symbiotic nitrogen fixing bacteria in root nodules of forage legume alfalfa (medicago sativa l.). in morocco, alfalfa is usually grown in marginal soils of arid and semi-arid regions frequently affected by drought, extremes of temperature and soil ph, soil salinity and heavy metals, which affect biological nitrogen fixing ability of rhizobia and productivity of the host. this study examines phenotypic diversity for tolerance to the above stresses and gen ... | 2010 | 20089174 |
| genome-wide detection of predicted non-coding rnas in rhizobium etli expressed during free-living and host-associated growth using a high-resolution tiling array. | non-coding rnas (ncrnas) play a crucial role in the intricate regulation of bacterial gene expression, allowing bacteria to quickly adapt to changing environments. in the past few years, a growing number of regulatory rna elements have been predicted by computational methods, mostly in well-studied gamma-proteobacteria but lately in several alpha-proteobacteria as well. here, we have compared an extensive compilation of these non-coding rna predictions to intergenic expression data of a whole-ge ... | 2010 | 20089193 |
| a type vi secretion system of pseudomonas aeruginosa targets a toxin to bacteria. | the functional spectrum of a secretion system is defined by its substrates. here we analyzed the secretomes of pseudomonas aeruginosa mutants altered in regulation of the hcp secretion island-i-encoded type vi secretion system (h1-t6ss). we identified three substrates of this system, proteins tse1-3 (type six exported 1-3), which are coregulated with the secretory apparatus and secreted under tight posttranslational control. the tse2 protein was found to be the toxin component of a toxin-immunit ... | 2010 | 20114026 |
| identification of a bifunctional udp-4-keto-pentose/udp-xylose synthase in the plant pathogenic bacterium ralstonia solanacearum strain gmi1000, a distinct member of the 4,6-dehydratase and decarboxylase family. | the udp-sugar interconverting enzymes involved in udp-glca metabolism are well described in eukaryotes but less is known in prokaryotes. here we identify and characterize a gene (rsu4kpxs) from ralstonia solanacearum str. gmi1000, which encodes a dual function enzyme not previously described. one activity is to decarboxylate udp-glucuronic acid to udp-beta-l-threo-pentopyranosyl-4''-ulose in the presence of nad(+). the second activity converts udp-beta-l-threo-pentopyranosyl-4''-ulose and nadh t ... | 2010 | 20118241 |
| ligands of boron in pisum sativum nodules are involved in regulation of oxygen concentration and rhizobial infection. | boron (b) is an essential nutrient for n(2)-fixing legume-rhizobia symbioses, and the capacity of borate ions to bind and stabilize biomolecules is the basis of any b function. we used a borate-binding-specific resin and immunostaining techniques to identify b ligands important for the development of pisum sativum-rhizobium leguminosarum 3841 symbiotic nodules. arabinogalactan-extensin (agpe), recognized by mac 265 antibody, appeared heavily bound to the resin in extracts derived from b-sufficie ... | 2010 | 20132519 |
| an efficient, multiply promiscuous hydrolase in the alkaline phosphatase superfamily. | we report a catalytically promiscuous enzyme able to efficiently promote the hydrolysis of six different substrate classes. originally assigned as a phosphonate monoester hydrolase (pmh) this enzyme exhibits substantial second-order rate accelerations ((k(cat)/k(m))/k(w)), ranging from 10(7) to as high as 10(19), for the hydrolyses of phosphate mono-, di-, and triesters, phosphonate monoesters, sulfate monoesters, and sulfonate monoesters. this substrate collection encompasses a range of substra ... | 2010 | 20133613 |
| genome-wide investigation and functional characterization of the beta-ketoadipate pathway in the nitrogen-fixing and root-associated bacterium pseudomonas stutzeri a1501. | soil microorganisms are mainly responsible for the complete mineralization of aromatic compounds that usually originate from plant products or environmental pollutants. in many cases, structurally diverse aromatic compounds can be converted to a small number of structurally simpler intermediates, which are metabolized to tricarboxylic acid intermediates via the beta-ketoadipate pathway. this strategy provides great metabolic flexibility and contributes to increased adaptation of bacteria to thei ... | 2010 | 20137101 |
| myxococcus xanthus viability depends on groel supplied by either of two genes, but the paralogs have different functions during heat shock, predation, and development. | myxococcus xanthus dk1622 contains two paralogous groel gene loci that possess both different sequences and different organizations within the genome. deletion of either one of these two genes alone does not affect cell viability. however, deletion of both groel genes results in cell death unless a complemented groel1 or groel2 gene is present. the groel1 gene was determined to be essential for cell survival under heat shock conditions; a strain with mutant groel2 caused cells to be more sensiti ... | 2010 | 20139189 |
| altered lipid a structures and polymyxin hypersensitivity of rhizobium etli mutants lacking the lpxe and lpxf phosphatases. | the lipid a of rhizobium etli, a nitrogen-fixing plant endosymbiont, displays significant structural differences when compared to that of escherichia coli. an especially striking feature of r. etli lipid a is that it lacks both the 1- and 4'-phosphate groups. the 4'-phosphate moiety of the distal glucosamine unit is replaced with a galacturonic acid residue. the dephosphorylated proximal unit is present as a mixture of the glucosamine hemiacetal and an oxidized 2-aminogluconate derivative. disti ... | 2010 | 20153447 |
| requirements for construction of a functional hybrid complex of photosystem i and [nife]-hydrogenase. | the development of cellular systems in which the enzyme hydrogenase is efficiently coupled to the oxygenic photosynthesis apparatus represents an attractive avenue to produce h(2) sustainably from light and water. here we describe the molecular design of the individual components required for the direct coupling of the o(2)-tolerant membrane-bound hydrogenase (mbh) from ralstonia eutropha h16 to the acceptor site of photosystem i (ps i) from synechocystis sp. pcc 6803. by genetic engineering, th ... | 2010 | 20154103 |
| a new small regulatory protein, hmup, modulates haemin acquisition in sinorhizobium meliloti. | sinorhizobium meliloti has multiple systems for iron acquisition, including the use of haem as an iron source. haem internalization involves the shmr haem outer membrane receptor and the hmutuv locus, which participates in haem transport across the cytoplasmic membrane. previous studies have demonstrated that expression of the shmr gene is negatively regulated by iron through rira. here, we identify hmup in a genetic screen for mutants that displayed aberrant control of shmr. the normal inductio ... | 2010 | 20167620 |
| role of the sinorhizobium meliloti global regulator hfq in gene regulation and symbiosis. | the rna-binding protein hfq is a global regulator which controls diverse cellular processes in bacteria. to begin understanding the role of hfq in the sinorhizobium meliloti-medicago truncatula nitrogen-fixing symbiosis, we defined free-living and symbiotic phenotypes of an hfq mutant. over 500 transcripts were differentially accumulated in the hfq mutant of s. meliloti rm1021 when grown in a shaking culture. consistent with transcriptome-wide changes, the hfq mutant displayed dramatic alteratio ... | 2010 | 20192823 |
| evolution and multifarious horizontal transfer of an alternative biosynthetic pathway for the alternative polyamine sym-homospermidine. | polyamines are small flexible organic polycations found in almost all cells. they likely existed in the last universal common ancestor of all extant life, and yet relatively little is understood about their biological function, especially in bacteria and archaea. unlike eukaryotes, where the predominant polyamine is spermidine, bacteria may contain instead an alternative polyamine, sym-homospermidine. we demonstrate that homospermidine synthase (hss) has evolved vertically, primarily in the alph ... | 2010 | 20194510 |
| regulation of flagellar, motility and chemotaxis genes in rhizobium leguminosarum by the visn/r-rem cascade. | in this paper, we describe the regulatory roles of visn, visr and rem in the expression of flagellar, motility and chemotaxis genes in rhizobium leguminosarum biovar viciae strains vf39sm and 3841. individual mutations in the genes encoding these proteins resulted in a loss of motility and an absence of flagella, indicating that these regulatory genes are essential for flagellar synthesis and function. transcriptional experiments involving gusa-gene fusions in wild-type and mutant backgrounds we ... | 2010 | 20203055 |
| the sinorhizobium meliloti rna chaperone hfq influences central carbon metabolism and the symbiotic interaction with alfalfa. | the bacterial hfq protein is able to interact with diverse rna molecules, including regulatory small non-coding rnas (srnas), and thus it is recognized as a global post-transcriptional regulator of gene expression. loss of hfq has an extensive impact in bacterial physiology which in several animal pathogens influences virulence. sinorhizobium meliloti is a model soil bacterium known for its ability to establish a beneficial nitrogen-fixing intracellular symbiosis with alfalfa. despite the predic ... | 2010 | 20205931 |
| udp xylose synthase 1 is required for morphogenesis and histogenesis of the craniofacial skeleton. | udp-xylose synthase (uxs1) is strongly conserved from bacteria to humans, but because no mutation has been studied in any animal, we do not understand its roles in development. furthermore, no crystal structure has been published. uxs1 synthesizes udp-xylose, which initiates glycosaminoglycan attachment to a protein core during proteoglycan formation. crystal structure and biochemical analyses revealed that an r233h substitution mutation in zebrafish uxs1 alters an arginine buried in the dimer i ... | 2010 | 20226781 |
| mutation in the pssm gene encoding ketal pyruvate transferase leads to disruption of rhizobium leguminosarum bv. viciae-pisum sativum symbiosis. | to study the question whether acidic exopolysaccharide (eps) modification, e.g. pyruvylation, plays any role in the development of rhizobium leguminosarum/pisum sativum symbiosis. | 2010 | 20233262 |
| heme-responsive dna binding by the global iron regulator irr from rhizobium leguminosarum. | heme, a physiologically crucial form of iron, is a cofactor for a very wide range of proteins and enzymes. these include dna regulatory proteins in which heme is a sensor to which an analyte molecule binds, effecting a change in the dna binding affinity of the regulator. given that heme, and more generally iron, must be carefully regulated, it is surprising that there are no examples yet in bacteria in which heme itself is sensed directly by a reversibly binding dna regulatory protein. here we s ... | 2010 | 20233710 |
| quorum-sensing regulation of a copper toxicity system in pseudomonas aeruginosa. | the lasr/lasi quorum-sensing system in pseudomonas aeruginosa influences global gene expression and mediates pathogenesis. in this study, we show that the quorum-sensing system activates, via the transcriptional regulator pa4778, a copper resistance system composed of 11 genes. the quorum-sensing global regulator lasr was recently shown to directly activate transcription of pa4778, a cuer homolog and a merr-type transcriptional regulator. using molecular genetic methods and bioinformatics, we ve ... | 2010 | 20233934 |
| some effects of 2,4-d, ddt, and colorado 9 on the bacteria rhizobium leguminosarum frank in the root nodules of the common bean. | | 1947 | 20252514 |
| glnb/glnk pii proteins and regulation of the sinorhizobium meliloti rm1021 nitrogen stress response and symbiotic function. | the sinorhizobium meliloti rm1021 delta glnd-sm2 mutant, which is predicted to make a glnd nitrogen sensor protein truncated at its amino terminus, fixes nitrogen in symbiosis with alfalfa, but the plants cannot use this nitrogen for growth (s. n. yurgel and m. l. kahn, proc. natl. acad. sci. u. s. a. 105:18958-18963, 2008). the mutant also has a generalized nitrogen stress response (nsr) defect. these results suggest a connection between glnd, symbiotic metabolism, and the nsr, but the nature o ... | 2010 | 20304991 |
| symbiotic functioning and bradyrhizobial biodiversity of cowpea (vigna unguiculata l. walp.) in africa. | cowpea is the most important food grain legume in sub-saharan africa. however, no study has so far assessed rhizobial biodiversity and/or nodule functioning in relation to strain igs types at the continent level. in this study, 9 cowpea genotypes were planted in field experiments in botswana, south africa and ghana with the aim of i) trapping indigenous cowpea root-nodule bacteria (cowpea "rhizobia") in the 3 countries for isolation, molecular characterisation using pcr-rflp analysis, and sequen ... | 2010 | 20331875 |
| genome-wide comparative analysis of metacaspases in unicellular and filamentous cyanobacteria. | cyanobacteria are an ancient group of photoautotrophic prokaryotes with wide variations in genome size and ecological habitat. metacaspases (mcas) are cysteine proteinases that have sequence homology to caspases and play essential roles in programmed cell death (pcd). mcas have been identified in several prokaryotes, fungi and plants; however, knowledge about cyanobacterial metacaspases still remains obscure. with the availability of sequenced genomes of 33 cyanobacteria, we perform a comparativ ... | 2010 | 20334693 |
| toxicogenomic response of rhodospirillum rubrum s1h to the micropollutant triclosan. | in the framework of the micro-ecological life support system alternative (melissa) project, a pilot study was performed to identify the effects of triclosan on the melissa carbon-mineralizing microorganism rhodospirillum rubrum s1h. triclosan is a biocide that is commonly found in human excrement and is considered an emerging pollutant in wastewater and the environment. chronic exposure to melissa-relevant concentrations (> or =25 microg liter(-1)) of triclosan resulted in a significant extensio ... | 2010 | 20363786 |
| baca is essential for bacteroid development in nodules of galegoid, but not phaseoloid, legumes. | baca is an integral membrane protein, the mutation of which leads to increased resistance to the antimicrobial peptides bleomycin and bac7(1-35) and a greater sensitivity to sds and vancomycin in rhizobium leguminosarum bv. viciae, r. leguminosarum bv. phaseoli, and rhizobium etli. the growth of rhizobium strains on dicarboxylates as a sole carbon source was impaired in baca mutants but was overcome by elevating the calcium level. while baca mutants elicited indeterminate nodule formation on pea ... | 2010 | 20363949 |
| stress-induced synthesis of phosphatidylinositol 3-phosphate in mycobacteria. | phosphoinositides play key roles in regulating membrane dynamics and intracellular signaling in eukaryotic cells. however, comparable lipid-based signaling pathways have not been identified in bacteria. here we show that mycobacterium smegmatis and other actinomycetes bacteria can synthesize the phosphoinositide, phosphatidylinositol 3-phosphate (pi3p). this lipid was transiently labeled with [(3)h]inositol. sensitivity of the purified lipid to alkaline phosphatase, headgroup analysis by high-pr ... | 2010 | 20364020 |
| monomethylamine as a nitrogen source for a nonmethylotrophic bacterium, agrobacterium tumefaciens. | monomethylamine can be used by nonmethylotrophs as a sole nitrogen source but not as a carbon source; however, little is known about the genes and enzymes involved. the gamma-glutamylmethylamide/n-methylglutamate pathway for monomethylamine utilization by methylotrophs has recently been resolved. we have identified genes encoding key enzymes of this pathway in nonmethylotrophs (e.g., agrobacterium tumefaciens) and demonstrated that this pathway is also involved in the utilization of monomethylam ... | 2010 | 20400554 |