| the rpg gene of medicago truncatula controls rhizobium-directed polar growth during infection. | rhizobia can infect roots of host legume plants and induce new organs called nodules, in which they fix atmospheric nitrogen. infection generally starts with root hair curling, then proceeds inside newly formed, intracellular tubular structures called infection threads. a successful symbiotic interaction relies on infection threads advancing rapidly at their tips by polar growth through successive cell layers of the root toward developing nodule primordia. to identify a plant component that cont ... | 2008 | 18621693 |
| virus-induced gene silencing (vigs) as a reverse genetic tool to study development of symbiotic root nodules. | virus-induced gene silencing (vigs) can provide a shortcut to plants with altered expression of specific genes. here, we report that vigs of the nodule inception gene (nin) can alter the nodulation phenotype and nin gene expression in pisum sativum. psnin was chosen as target because of the distinct non-nodulating phenotype of nin mutants in p. sativum, lotus japonicus, and medicago truncatula. the vector based on pea early browning virus (pebv) was engineered to carry one of three nonoverlappin ... | 2008 | 18624636 |
| function of a chemotaxis-like signal transduction pathway in modulating motility, cell clumping, and cell length in the alphaproteobacterium azospirillum brasilense. | a chemotaxis signal transduction pathway (hereafter called che1) has been previously identified in the alphaproteobacterium azospirillum brasilense. previous experiments have demonstrated that although mutants lacking cheb and/or cher homologs from this pathway are defective in chemotaxis, a mutant in which the entire chemotaxis pathway has been mutated displayed a chemotaxis phenotype mostly similar to that of the parent strain, suggesting that the primary function of this che1 pathway is not t ... | 2008 | 18641130 |
| tsr-gfp accumulates linearly with time at cell poles, and can be used to differentiate 'old' versus 'new' poles, in escherichia coli. | summary: in escherichia coli, the chemotaxis receptor protein tsr localizes abundantly to cell poles. the current study, utilizing a tsr-gfp fusion protein and time-lapse fluorescence microscopy of individual cell lineages, demonstrates that tsr accumulates approximately linearly with time at the cell poles and that, in consequence, more tsr is present at the old pole of each cell than at its newborn pole. the rate of pole-localized tsr accumulation is large enough that old and new poles can alw ... | 2008 | 18647166 |
| plastic architecture of bacterial genome revealed by comparative genomics of photorhabdus variants. | the phenotypic consequences of large genomic architecture modifications within a clonal bacterial population are rarely evaluated because of the difficulties associated with using molecular approaches in a mixed population. bacterial variants frequently arise among photorhabdus luminescens, a nematode-symbiotic and insect-pathogenic bacterium. we therefore studied genome plasticity within photorhabdus variants. | 2008 | 18647395 |
| complete genome sequence of the n2-fixing broad host range endophyte klebsiella pneumoniae 342 and virulence predictions verified in mice. | we report here the sequencing and analysis of the genome of the nitrogen-fixing endophyte, klebsiella pneumoniae 342. although k. pneumoniae 342 is a member of the enteric bacteria, it serves as a model for studies of endophytic, plant-bacterial associations due to its efficient colonization of plant tissues (including maize and wheat, two of the most important crops in the world), while maintaining a mutualistic relationship that encompasses supplying organic nitrogen to the host plant. genomic ... | 2008 | 18654632 |
| purification and mutagenesis of lpxl, the lauroyltransferase of escherichia coli lipid a biosynthesis. | escherichia coli lipid a is a hexaacylated disaccharide of glucosamine with secondary laurate and myristate chains on the distal unit. hexaacylated lipid a is a potent agonist of human toll-like receptor 4, whereas its tetra- and pentaacylated precursors are antagonists. the inner membrane enzyme lpxl transfers laurate from lauroyl-acyl carrier protein to the 2'- r-3-hydroxymyristate moiety of the tetraacylated lipid a precursor kdo 2-lipid iv a. lpxl has now been overexpressed, solubilized with ... | 2008 | 18656959 |
| construction of signature-tagged mutant library in mesorhizobium loti as a powerful tool for functional genomics. | rhizobia are nitrogen-fixing soil bacteria that establish endosymbiosis with some leguminous plants. the completion of several rhizobial genome sequences provides opportunities for genome-wide functional studies of the physiological roles of many rhizobial genes. in order to carry out genome-wide phenotypic screenings, we have constructed a large mutant library of the nitrogen-fixing symbiotic bacterium, mesorhizobium loti, by transposon mutagenesis. transposon insertion mutants were generated u ... | 2008 | 18658183 |
| formate-dependent autotrophic growth in sinorhizobium meliloti. | it was found that s. meliloti strain sma818, which is cured of psyma, could not grow on defined medium containing only formate and bicarbonate as carbon sources. growth experiments showed that rm1021 was capable of formate/bicarbonate-dependent growth, suggesting that it was capable of autotrophic-type growth. the annotated genome of s. meliloti rm1021 contains three formate dehydrogenase genes. a systematic disruption of each of the three formate dehydrogenase genes, as well as the genes encodi ... | 2008 | 18658261 |
| identification and characterization of the dicarboxylate uptake system dcct in corynebacterium glutamicum. | many bacteria can utilize c(4)-carboxylates as carbon and energy sources. however, corynebacterium glutamicum atcc 13032 is not able to use tricarboxylic acid cycle intermediates such as succinate, fumarate, and l-malate as sole carbon sources. upon prolonged incubation, spontaneous mutants which had gained the ability to grow on succinate, fumarate, and l-malate could be isolated. dna microarray analysis showed higher mrna levels of cg0277, which subsequently was named dcct, in the mutants than ... | 2008 | 18658264 |
| response to flavonoids as a factor influencing competitiveness and symbiotic activity of rhizobium leguminosarum. | flavonoids play a crucial role as signal molecules in promoting the formation of nodules by symbiotic bacteria commonly known as rhizobia. the early interaction between flavonoids and nodd regulatory protein activates nod gene transcription and the synthesis of nod factor that initiates nodule primordium. in this study, we assessed response to flavonoids as factors influencing competitiveness of rhizobia and their symbiotic activity. rhizobium leguminosarum nodule isolates belonging to three bio ... | 2010 | 18678476 |
| whole-genome transcriptional profiling of bradyrhizobium japonicum during chemoautotrophic growth. | bradyrhizobium japonicum is a facultative chemoautotroph capable of utilizing hydrogen gas as an electron donor in a respiratory chain terminated by oxygen to provide energy for cellular processes and carbon dioxide assimilation via a reductive pentose phosphate pathway. a transcriptomic analysis of b. japonicum cultured chemoautotrophically identified 1,485 transcripts, representing 17.5% of the genome, as differentially expressed when compared to heterotrophic cultures. genetic determinants re ... | 2008 | 18689488 |
| amino acid polymorphisms in strictly conserved domains of a p-type atpase hma5 are involved in the mechanism of copper tolerance variation in arabidopsis. | copper (cu) is an essential element in plant nutrition, but it inhibits the growth of roots at low concentrations. accessions of arabidopsis (arabidopsis thaliana) vary in their tolerance to cu. to understand the molecular mechanism of cu tolerance in arabidopsis, we performed quantitative trait locus (qtl) analysis and accession studies. one major qtl on chromosome 1 (qtl1) explained 52% of the phenotypic variation in cu tolerance in roots in a landsberg erecta/cape verde islands (ler/cvi) reco ... | 2008 | 18701674 |
| characterization of the quaternary amine transporters of rhizobium leguminosarum bv. viciae 3841. | rhizobium leguminosarum bv. viciae 3841 contains six putative quaternary ammonium transporters (qat), of the abc family. qat6 was strongly induced by hyperosmosis although the solute transported was not identified. all six systems were induced by the quaternary amines choline and glycine betaine. it was confirmed by microarray analysis of the genome that prl100079-83 (qat6) is the most strongly upregulated transport system under osmotic stress, although other transporters and 104 genes are more ... | 2008 | 18721149 |
| organization and evolution of the biological response to singlet oxygen stress. | the appearance of atmospheric oxygen from photosynthetic activity led to the evolution of aerobic respiration and responses to the resulting reactive oxygen species. in rhodobacter sphaeroides, a photosynthetic alpha-proteobacterium, a transcriptional response to the reactive oxygen species singlet oxygen ((1)o(2)) is controlled by the group iv sigma factor sigma(e) and the anti-sigma factor chrr. in this study, we integrated various large datasets to identify genes within the (1)o(2) stress res ... | 2008 | 18723027 |
| nodd binds to target dna in isologous octamer. | nodd, the major regulatory protein of nodulation, was partially purified from rhizobium leguminosarum 8401(pij1518), and its binding sequences within nodf promoter of r. l. bv. viciae were determined by dnase i footprinting. a series of techniques based on gel retardation were used to analyze the nodd-target dna interaction, showing that nodd binds to target dna in isologous octamer. | 1998 | 18726214 |
| genetic diversity of root-nodulating bacteria isolated from pea (pisum sativum) in subtropical regions of china. | diversity of 42 isolates from effective nodules of pisum sativum in different geographical regions of china were studied using 16s rrna gene rflp patterns, 16s rrna sequencing, 16s-23s rrna intergenic spacer (igs) region rflp patterns and g-c rich random amplified polymorphic dna (rapd). the isolates were distributed in two groups on the basis of their 16s rrna gene rflp patterns. the 16s rrna gene sequences of strains from 16s rrna gene rflp patterns group i were very closely related (identitie ... | 2008 | 18726533 |
| shmr is essential for utilization of heme as a nutritional iron source in sinorhizobium meliloti. | the bacterium sinorhizobium meliloti is able to use heme as a nutritional iron source. here, we show that the iron-regulated shmr gene encodes an outer membrane protein required for growth on heme. furthermore, an shmr mutant is resistant to the toxic heme analog gallium protoporphyrin. thus, the receptor protein of the heme transport system has been identified in s. meliloti. | 2008 | 18757569 |
| combining winter hardiness and forage yield in white clover (trifolium repens) cultivated in northern environments. | white clover (trifolium repens) is an important component of sustainable livestock systems around the world. its exploitation for agriculture in the northern, marginal areas is, however, currently limited by the lack of cultivars that combine persistence and high production potential. the aims are to investigate whether it is feasible to create breeding material of white clover for these areas by combining winter hardiness of northerly populations with good yielding ability of more southerly cul ... | 2008 | 18772149 |
| prediction of sinorhizobium meliloti srna genes and experimental detection in strain 2011. | small non-coding rnas (srnas) have emerged as ubiquitous regulatory elements in bacteria and other life domains. however, few srnas have been identified outside several well-studied species of gamma-proteobacteria and thus relatively little is known about the role of rna-mediated regulation in most other bacterial genera. here we have conducted a computational prediction of putative srna genes in intergenic regions (igrs) of the symbiotic alpha-proteobacterium s. meliloti 1021 and experimentally ... | 2008 | 18793445 |
| a new member of the alkaline phosphatase superfamily with a formylglycine nucleophile: structural and kinetic characterisation of a phosphonate monoester hydrolase/phosphodiesterase from rhizobium leguminosarum. | the alkaline phosphatase superfamily comprises a large number of hydrolytic metalloenzymes such as phosphatases and sulfatases. we have characterised a new member of this superfamily, a phosphonate monoester hydrolase/phosphodiesterase from rhizobium leguminosarum (r/pmh) both structurally and kinetically. the 1.42 a crystal structure shows structural homology to arylsulfatases with conservation of the core alpha/beta-fold, the mononuclear active site and most of the active-site residues. sulfat ... | 2008 | 18793651 |
| poly-beta-hydroxybutyrate production by fast-growing rhizobia cultivated in sludge and in industrial wastewater. | in our study, the potential of producing polyhydroxybutyrate (phb) by cultivating fast-growing rhizobia (sinorhizobium meliloti, rhizobium leguminosarum bv. viciae, r. leguminosarum bv. phaseoli and r. leguminosarum bv. trifolii) in sludge and in industrial wastewater was evaluated. results confirmed the possibility of using sludge as media for rhizobial growth. during growth, substantial quantity of phb was accumulated and yields varied depending on the media and rhizobial species. growing in s ... | 2009 | 18795238 |
| lack of genomic evidence of ai-2 receptors suggests a non-quorum sensing role for luxs in most bacteria. | great excitement accompanied discoveries over the last decade in several gram-negative and gram-positive bacteria of the luxs protein, which catalyzes production of the ai-2 autoinducer molecule for a second quorum sensing system (qs-2). since the luxs gene was found to be widespread among the most diverse bacterial taxa, it was hypothesized that ai-2 may constitute the basis of a universal microbial language, a kind of bacterial esperanto. many of the studies published in this field have drawn ... | 2008 | 18803868 |
| scin is an outer membrane lipoprotein required for type vi secretion in enteroaggregative escherichia coli. | enteroaggregative escherichia coli (eaec) is a pathogen implicated in several infant diarrhea or diarrheal outbreaks in areas of endemicity. although multiple genes involved in eaec pathogenesis have been identified, the overall mechanism of virulence is not well understood. recently, a novel secretion system, called type vi secretion (t6s) system (t6ss), has been identified in eaec and most animal or plant gram-negative pathogens. t6sss are multicomponent cell envelope machines responsible for ... | 2008 | 18805985 |
| psso, a unique extracellular protein important for exopolysaccharide synthesis in rhizobium leguminosarum bv. trifolii. | synthesis and secretion of polysaccharides by gram-negative bacteria are a result of a concerted action of enzymatic and channel-forming proteins localized in different compartments of the cell. the presented work comprises functional characterization of psso protein encoded within the previously identified, chromosomal exopolysaccharide (eps) biosynthesis region (pss-i) of symbiotic bacterium rhizobium leguminosarum bv. trifolii ta1 (rtta1). psso gene localization between pssn and pssp genes en ... | 2008 | 18835420 |
| symbiotic plasmid is required for nolr to fully repress nodulation genes in rhizobium leguminosarum a34. | nolr is a regulator of nodulation genes present in rhizobium and sinorhizobium. however, the mechanism by which nolr participates in the inducible transcription of nodulation genes remains unclear. to investigate whether there are other factors regulating the function of nolr, an insertion mutant of nolr in rhizobium leguminosarum strain 8401, which lacks the symbiotic plasmid, was constructed by homologous recombination. we investigated the effects of nolr inactivation on the expression of nodu ... | 2008 | 18850056 |
| expression and physiological relevance of agrobacterium tumefaciens phosphatidylcholine biosynthesis genes. | phosphatidylcholine (pc), or lecithin, is the major phospholipid in eukaryotic membranes, whereas only 10% of all bacteria are predicted to synthesize pc. in rhizobiaceae, including the phytopathogenic bacterium agrobacterium tumefaciens, pc is essential for the establishment of a successful host-microbe interaction. a. tumefaciens produces pc via two alternative pathways, the methylation pathway and the pcs pathway. the responsible genes, pmta (coding for a phospholipid n-methyltransferase) and ... | 2009 | 18978052 |
| expression and physiological relevance of agrobacterium tumefaciens phosphatidylcholine biosynthesis genes. | phosphatidylcholine (pc), or lecithin, is the major phospholipid in eukaryotic membranes, whereas only 10% of all bacteria are predicted to synthesize pc. in rhizobiaceae, including the phytopathogenic bacterium agrobacterium tumefaciens, pc is essential for the establishment of a successful host-microbe interaction. a. tumefaciens produces pc via two alternative pathways, the methylation pathway and the pcs pathway. the responsible genes, pmta (coding for a phospholipid n-methyltransferase) and ... | 2009 | 18978052 |
| the luxr family quorum-sensing activator mrtr requires its cognate autoinducer for dimerization and activation but not for protein folding. | mrtr, a luxr homolog in mesorhizobium tianshanense, is important for symbiosis. we found that mrtr requires its cognate n-acylhomoserine lactone for forming dimers, binding to a single dna site and activating the downstream promoter. however, mrtr is able to fold independently of its ligand. | 2009 | 18978063 |
| the luxr family quorum-sensing activator mrtr requires its cognate autoinducer for dimerization and activation but not for protein folding. | mrtr, a luxr homolog in mesorhizobium tianshanense, is important for symbiosis. we found that mrtr requires its cognate n-acylhomoserine lactone for forming dimers, binding to a single dna site and activating the downstream promoter. however, mrtr is able to fold independently of its ligand. | 2009 | 18978063 |
| function, regulation, and transcriptional organization of the hemin utilization locus of bartonella quintana. | bartonella quintana is a gram-negative agent of trench fever, chronic bacteremia, endocarditis, and bacillary angiomatosis in humans. b. quintana has the highest known hemin requirement among bacteria, but the mechanisms of hemin acquisition are poorly defined. genomic analyses revealed a potential locus dedicated to hemin utilization (hut) encoding a putative hemin receptor, huta; a tonb-like energy transducer; an abc transport system comprised of three proteins, hutb, hutc, and hmuv; and a hem ... | 2009 | 18981245 |
| function, regulation, and transcriptional organization of the hemin utilization locus of bartonella quintana. | bartonella quintana is a gram-negative agent of trench fever, chronic bacteremia, endocarditis, and bacillary angiomatosis in humans. b. quintana has the highest known hemin requirement among bacteria, but the mechanisms of hemin acquisition are poorly defined. genomic analyses revealed a potential locus dedicated to hemin utilization (hut) encoding a putative hemin receptor, huta; a tonb-like energy transducer; an abc transport system comprised of three proteins, hutb, hutc, and hmuv; and a hem ... | 2009 | 18981245 |
| molecular determinants of a symbiotic chronic infection. | rhizobial bacteria colonize legume roots for the purpose of biological nitrogen fixation. a complex series of events, coordinated by host and bacterial signal molecules, underlie the development of this symbiotic interaction. rhizobia elicit de novo formation of a novel root organ within which they establish a chronic intracellular infection. legumes permit rhizobia to invade these root tissues while exerting control over the infection process. once rhizobia gain intracellular access to their ho ... | 2008 | 18983260 |
| purification and characterization of the lipid a 1-phosphatase lpxe of rhizobium leguminosarum. | lpxe, a membrane-bound phosphatase found in rhizobium leguminosarum and some other gram-negative bacteria, selectively dephosphorylates the 1-position of lipid a on the outer surface of the inner membrane. lpxe belongs to the family of lipid phosphate phosphatases that contain a tripartite active site motif and six predicted transmembrane helices. here we report the purification and characterization of r. leguminosarum lpxe. a modified lpxe gene, encoding a protein with an n-terminal his6 tag, w ... | 2009 | 18984595 |
| revision of the taxonomic status of the species rhizobium leguminosarum (frank 1879) frank 1889al, rhizobium phaseoli dangeard 1926al and rhizobium trifolii dangeard 1926al. r. trifolii is a later synonym of r. leguminosarum. reclassification of the strain r. leguminosarum dsm 30132 (=ncimb 11478) as rhizobium pisi sp. nov. | the taxonomic status of the species rhizobium leguminosarum, rhizobium trifolii and rhizobium phaseoli was analysed in this study on the basis of their molecular and phenotypic characteristics. according to the results, the type strain r. phaseoli atcc 14482(t) does not belong to any of the already described species of the genus rhizobium and it should therefore be considered as a different species. in contrast, the strains of r. trifolii examined belonged to r. leguminosarum and thus r. trifoli ... | 2008 | 18984681 |
| the pea sym37 receptor kinase gene controls infection-thread initiation and nodule development. | phenotypic characterization of pea symbiotic mutants has provided a detailed description of the symbiosis with rhizobium leguminosarum bv. viciae strains. we show here that two allelic non-nodulating pea mutants, risnod4 and k24, are affected in the pssym37 gene, encoding a lysm receptor kinase similar to lotus japonicus nfr1 and medicago truncatula lyk3. phenotypic analysis of risnod4 and k24 suggests a role for the sym37 in regulation of infection-thread initiation and nodule development from ... | 2008 | 18986256 |
| the transcriptional repressor protein nsrr senses nitric oxide directly via a [2fe-2s] cluster. | the regulatory protein nsrr, a member of the rrf2 family of transcription repressors, is specifically dedicated to sensing nitric oxide (no) in a variety of pathogenic and non-pathogenic bacteria. it has been proposed that no directly modulates nsrr activity by interacting with a predicted [fe-s] cluster in the nsrr protein, but no experimental evidence has been published to support this hypothesis. here we report the purification of nsrr from the obligate aerobe streptomyces coelicolor. we demo ... | 2008 | 18989365 |
| survival of rhizobia in two soils as influenced by storage conditions. | two soils were kept moist at 4 degrees c, -20 degrees c or air-dried at 20-22 degrees c and after one week, one month, two months and six months of storage at these conditions changes in soil populations of rhizobium leguminosarum bv. trifolii (rlt) and rhizobium leguminosarum bv. viciae (rlv) were examined. in one air-dried soil (from grab6w) markedly lower numbers of both rlt and rlv., as compared to the refrigerated or frozen samples, were found already after 1 week of storage. in the case of ... | 2008 | 19004248 |
| characterization of the myo-inositol utilization island of salmonella enterica serovar typhimurium. | knockout mutation of stm4432 resulted in a growth-deficient phenotype of salmonella enterica serovar typhimurium in the presence of myo-inositol (mi) as the sole carbon source. stm4432 is part of a 22.6-kb genomic island which spans stm4417 to stm4436 (genomic island 4417/4436) and is responsible for mi degradation. genome comparison revealed the presence of this island in only six salmonella strains and a high variability of the iol gene organization in gram-negative bacteria. upon nonpolar del ... | 2009 | 19011032 |
| characterization of the myo-inositol utilization island of salmonella enterica serovar typhimurium. | knockout mutation of stm4432 resulted in a growth-deficient phenotype of salmonella enterica serovar typhimurium in the presence of myo-inositol (mi) as the sole carbon source. stm4432 is part of a 22.6-kb genomic island which spans stm4417 to stm4436 (genomic island 4417/4436) and is responsible for mi degradation. genome comparison revealed the presence of this island in only six salmonella strains and a high variability of the iol gene organization in gram-negative bacteria. upon nonpolar del ... | 2009 | 19011032 |
| the blcc (attm) lactonase of agrobacterium tumefaciens does not quench the quorum-sensing system that regulates ti plasmid conjugative transfer. | the conjugative transfer of agrobacterium plasmids is controlled by a quorum-sensing system consisting of trar and its acyl-homoserine lactone (hsl) ligand. the acyl-hsl is essential for the trar-mediated activation of the ti plasmid tra genes. strains a6 and c58 of agrobacterium tumefaciens produce a lactonase, blcc (attm), that can degrade the quormone, leading some to conclude that the enzyme quenches the quorum-sensing system. we tested this hypothesis by examining the effects of the mutatio ... | 2009 | 19011037 |
| the blcc (attm) lactonase of agrobacterium tumefaciens does not quench the quorum-sensing system that regulates ti plasmid conjugative transfer. | the conjugative transfer of agrobacterium plasmids is controlled by a quorum-sensing system consisting of trar and its acyl-homoserine lactone (hsl) ligand. the acyl-hsl is essential for the trar-mediated activation of the ti plasmid tra genes. strains a6 and c58 of agrobacterium tumefaciens produce a lactonase, blcc (attm), that can degrade the quormone, leading some to conclude that the enzyme quenches the quorum-sensing system. we tested this hypothesis by examining the effects of the mutatio ... | 2009 | 19011037 |
| encapsulated in silica: genome, proteome and physiology of the thermophilic bacterium anoxybacillus flavithermus wk1. | gram-positive bacteria of the genus anoxybacillus have been found in diverse thermophilic habitats, such as geothermal hot springs and manure, and in processed foods such as gelatin and milk powder. anoxybacillus flavithermus is a facultatively anaerobic bacterium found in super-saturated silica solutions and in opaline silica sinter. the ability of a. flavithermus to grow in super-saturated silica solutions makes it an ideal subject to study the processes of sinter formation, which might be sim ... | 2008 | 19014707 |
| a mutant glnd nitrogen sensor protein leads to a nitrogen-fixing but ineffective sinorhizobium meliloti symbiosis with alfalfa. | the nitrogen-fixing symbiosis between rhizobia and legume plants is a model of coevolved nutritional complementation. the plants reduce atmospheric co(2) by photosynthesis and provide carbon compounds to symbiotically associated bacteria; the rhizobia use these compounds to reduce (fix) atmospheric n(2) to ammonia, a form of nitrogen the plants can use. a key feature of symbiotic n(2) fixation is that n(2) fixation is uncoupled from bacterial nitrogen stress metabolism so that the rhizobia gener ... | 2008 | 19020095 |
| new taxonomic markers for identification of rhizobium leguminosarum and discrimination between closely related species. | rhizobia, producing species-specific exopolysaccharides (epss), comprise a very diverse group of soil bacteria that are able to establish nitrogen-fixing symbioses with legumes. based on the sequences of r. leguminosarum eps synthesis genes, a sensitive and reliable pcr-based method for identification and subsequent discrimination between rhizobium species has been developed and tested. for identification of r. leguminosarum, primer sets i-iii complementary to sequences of rosr, pssa and pssy ge ... | 2009 | 19020864 |
| oryr is a luxr-family protein involved in interkingdom signaling between pathogenic xanthomonas oryzae pv. oryzae and rice. | xanthomonas oryzae pv. oryzae, the causal agent of bacterial leaf blight in rice, contains a regulator that is encoded in the genome, designated oryr, which belongs to the n-acyl homoserine lactone (ahl)-dependent quorum-sensing luxr subfamily of proteins. however, we previously reported that x. oryzae pv. oryzae does not make ahls and does not possess a luxi-family ahl synthase and that the oryr protein is solubilized by a compound present in rice. in this study we obtained further evidence tha ... | 2009 | 19028884 |
| oryr is a luxr-family protein involved in interkingdom signaling between pathogenic xanthomonas oryzae pv. oryzae and rice. | xanthomonas oryzae pv. oryzae, the causal agent of bacterial leaf blight in rice, contains a regulator that is encoded in the genome, designated oryr, which belongs to the n-acyl homoserine lactone (ahl)-dependent quorum-sensing luxr subfamily of proteins. however, we previously reported that x. oryzae pv. oryzae does not make ahls and does not possess a luxi-family ahl synthase and that the oryr protein is solubilized by a compound present in rice. in this study we obtained further evidence tha ... | 2009 | 19028884 |
| identification and characterization of a bacterial transport system for the uptake of pyruvate, propionate, and acetate in corynebacterium glutamicum. | the metabolism of monocarboxylic acids is of central importance for bacteria in their natural habitat as well as during biotechnological production. although biosynthesis and degradation are well understood, the transport of such compounds is still a matter of discussion. here we present the identification and characterization of a new transport system in corynebacterium glutamicum with high affinity for acetate and propionate and with lower affinity for pyruvate. biochemical analysis of this mo ... | 2009 | 19028892 |
| identification and characterization of a bacterial transport system for the uptake of pyruvate, propionate, and acetate in corynebacterium glutamicum. | the metabolism of monocarboxylic acids is of central importance for bacteria in their natural habitat as well as during biotechnological production. although biosynthesis and degradation are well understood, the transport of such compounds is still a matter of discussion. here we present the identification and characterization of a new transport system in corynebacterium glutamicum with high affinity for acetate and propionate and with lower affinity for pyruvate. biochemical analysis of this mo ... | 2009 | 19028892 |
| regulatory and dna repair genes contribute to the desiccation resistance of sinorhizobium meliloti rm1021. | sinorhizobium meliloti can form a nitrogen-fixing symbiotic relationship with alfalfa after bacteria in the soil infect emerging root hairs of the growing plant. to be successful at this, the bacteria must be able to survive in the soil between periods of active plant growth, including when conditions are dry. the ability of s. meliloti to withstand desiccation has been known for years, but genes that contribute to this phenotype have not been identified. transposon mutagenesis was used in combi ... | 2009 | 19028909 |
| regulatory and dna repair genes contribute to the desiccation resistance of sinorhizobium meliloti rm1021. | sinorhizobium meliloti can form a nitrogen-fixing symbiotic relationship with alfalfa after bacteria in the soil infect emerging root hairs of the growing plant. to be successful at this, the bacteria must be able to survive in the soil between periods of active plant growth, including when conditions are dry. the ability of s. meliloti to withstand desiccation has been known for years, but genes that contribute to this phenotype have not been identified. transposon mutagenesis was used in combi ... | 2009 | 19028909 |
| newly introduced genomic prophage islands are critical determinants of in vivo competitiveness in the liverpool epidemic strain of pseudomonas aeruginosa. | pseudomonas aeruginosa isolates have a highly conserved core genome representing up to 90% of the total genomic sequence with additional variable accessory genes, many of which are found in genomic islands or islets. the identification of the liverpool epidemic strain (les) in a children's cystic fibrosis (cf) unit in 1996 and its subsequent observation in several centers in the united kingdom challenged the previous widespread assumption that cf patients acquire only unique strains of p. aerugi ... | 2009 | 19047519 |
| cloning, purification, crystallization and preliminary x-ray analysis of a bacterial gaba receptor with a venus flytrap fold. | in response to infection by the pathogen agrobacterium tumefaciens, plants synthesize several stress amino acids, including gamma-aminobutyric acid (gaba), which modulates the expression of bacterial virulence factors. gaba penetrates into the bacterial cytoplasm via an abc transporter that is associated with the periplasmic receptor atu2422. mature receptor atu2422 (without its signal peptide) was overexpressed in escherichia coli, purified and crystallized. a complete data set was collected to ... | 2008 | 19052373 |
| rhizobium fabae sp. nov., a bacterium that nodulates vicia faba. | six strains were isolated from root nodules of vicia faba grown in nanchang, yifeng, taihu, huaibei, bengbu and lujiang, in the middle and lower reaches of the yangtze river. according to phylogenetic analyses of 16s rrna gene, atpd and reca sequences, these strains belong to the genus rhizobium, with rhizobium etli and rhizobium leguminosarum as the closest related species. ccbau 33202(t), a representative of these novel isolates, showed sequence similarity to its closest relatives r. etli cfn ... | 2008 | 19060074 |
| purine utilization by klebsiella oxytoca m5al: genes for ring-oxidizing and -opening enzymes. | the enterobacterium klebsiella oxytoca uses a variety of inorganic and organic nitrogen sources, including purines, nitrogen-rich compounds that are widespread in the biosphere. we have identified a 23-gene cluster that encodes the enzymes for utilizing purines as the sole nitrogen source. growth and complementation tests with insertion mutants, combined with sequence comparisons, reveal functions for the products of these genes. here, we report our characterization of 12 genes, one encoding gua ... | 2009 | 19060149 |
| purine utilization by klebsiella oxytoca m5al: genes for ring-oxidizing and -opening enzymes. | the enterobacterium klebsiella oxytoca uses a variety of inorganic and organic nitrogen sources, including purines, nitrogen-rich compounds that are widespread in the biosphere. we have identified a 23-gene cluster that encodes the enzymes for utilizing purines as the sole nitrogen source. growth and complementation tests with insertion mutants, combined with sequence comparisons, reveal functions for the products of these genes. here, we report our characterization of 12 genes, one encoding gua ... | 2009 | 19060149 |
| delayed maturation of nodules reduces symbiotic effectiveness of the lotus japonicus-rhizobium sp. ngr234 interaction. | lotus japonicus, a model legume, develops an efficient, nitrogen-fixing symbiosis with mesorhizobium loti that promotes plant growth. lotus japonicus also forms functional nodules with rhizobium sp. ngr234 and r. etli. yet, in a plant defence-like reaction, nodules induced by r. etli quickly degenerate, thus limiting plant growth. in contrast, nodules containing ngr234 are long-lasting. it was found that ngr234 initiates nodule formation in a similar way to m. loti maff303099, but that the nodul ... | 2009 | 19060298 |
| delayed maturation of nodules reduces symbiotic effectiveness of the lotus japonicus-rhizobium sp. ngr234 interaction. | lotus japonicus, a model legume, develops an efficient, nitrogen-fixing symbiosis with mesorhizobium loti that promotes plant growth. lotus japonicus also forms functional nodules with rhizobium sp. ngr234 and r. etli. yet, in a plant defence-like reaction, nodules induced by r. etli quickly degenerate, thus limiting plant growth. in contrast, nodules containing ngr234 are long-lasting. it was found that ngr234 initiates nodule formation in a similar way to m. loti maff303099, but that the nodul ... | 2009 | 19060298 |
| essential role for the baca protein in the uptake of a truncated eukaryotic peptide in sinorhizobium meliloti. | the inner membrane baca protein is essential for the establishment of chronic intracellular infections by sinorhizobium meliloti and brucella abortus within plant and mammalian hosts, respectively. in their free-living state, s. meliloti and b. abortus mutants lacking baca have reductions in their outer membrane lipid a very-long-chain fatty acid (vlcfa) contents and exhibit low-level resistance to the glycopeptide bleomycin in comparison to their respective parent strains. in this paper we inve ... | 2009 | 19074376 |
| essential role for the baca protein in the uptake of a truncated eukaryotic peptide in sinorhizobium meliloti. | the inner membrane baca protein is essential for the establishment of chronic intracellular infections by sinorhizobium meliloti and brucella abortus within plant and mammalian hosts, respectively. in their free-living state, s. meliloti and b. abortus mutants lacking baca have reductions in their outer membrane lipid a very-long-chain fatty acid (vlcfa) contents and exhibit low-level resistance to the glycopeptide bleomycin in comparison to their respective parent strains. in this paper we inve ... | 2009 | 19074376 |
| engineered biosynthesis of bacterial aromatic polyketides in escherichia coli. | bacterial aromatic polyketides are important therapeutic compounds including front line antibiotics and anticancer drugs. it is one of the last remaining major classes of natural products of which the biosynthesis has not been reconstituted in the genetically superior host escherichia coli. here, we demonstrate the engineered biosynthesis of bacterial aromatic polyketides in e. coli by using a dissected and reassembled fungal polyketide synthase (pks). the minimal pks of the megasynthase pks4 fr ... | 2008 | 19075227 |
| rhizobium leguminosarum bv. trifolii rosr gene expression is regulated by catabolic repression. | rhizobium leguminosarum bv. trifolii rosr gene encodes a transcriptional regulator involved in the positive regulation of exopolysaccharide synthesis. transcription of rosr is directed by two promoters, distal p1 and proximal p2, of different strengths. we demonstrated that rosr p1 functions as the main promoter and, besides the -35 and -10 sequences, it contains two other important regulatory elements, an extended -10 motif and an upstream promoter element, that play a significant role in the i ... | 2009 | 19077060 |
| pleiotropic effects of a rel mutation on stress survival of rhizobium etli cnpaf512. | the rel gene of rhizobium etli (relret), the nodulating endosymbiont of the common bean plant, determines the cellular level of the alarmone (p)ppgpp and was previously shown to affect free-living growth and symbiosis. here, we demonstrate its role in cellular adaptation and survival in response to various stresses. | 2008 | 19077212 |
| an orphan luxr homolog of sinorhizobium meliloti affects stress adaptation and competition for nodulation. | the sin/expr quorum-sensing system of sinorhizobium meliloti plays an important role in the symbiotic association with its host plant, medicago sativa. the luxr-type response regulators of the sin system include the synthase (sini)-associated sinr and the orphan regulator expr. interestingly, the s. meliloti rm1021 genome codes for four additional putative orphan luxr homologs whose regulatory roles remain to be identified. these response regulators contain the characteristic domains of the luxr ... | 2009 | 19088317 |
| an orphan luxr homolog of sinorhizobium meliloti affects stress adaptation and competition for nodulation. | the sin/expr quorum-sensing system of sinorhizobium meliloti plays an important role in the symbiotic association with its host plant, medicago sativa. the luxr-type response regulators of the sin system include the synthase (sini)-associated sinr and the orphan regulator expr. interestingly, the s. meliloti rm1021 genome codes for four additional putative orphan luxr homologs whose regulatory roles remain to be identified. these response regulators contain the characteristic domains of the luxr ... | 2009 | 19088317 |
| identification of a novel regulator for the escherichia coli fit iron transport system. | the escherichia coli fit iron transport system consists of 6 genes, fita, b, c, d, e and fitr. based on in silico analysis, fita-e composes a typical bacterial iron transporter, while fitr was deduced to be a regulator. in this paper the regulation of fit expression by fitr was studied using a quantitative rt-pcr technique and a lacz reporter assay. it was found that fit expression was repressed when fitr was over-expressed and de-repressed when fitr was knocked out by mutation. when the mutatio ... | 2008 | 19088918 |
| heme-dependent metalloregulation by the iron response regulator (irr) protein in rhizobium and other alpha-proteobacteria. | perception and response to nutritional iron by bacteria is essential for viability, and for the ability to adapt to the environment. the iron response regulator (irr) is part of a novel regulatory scheme employed by rhizobium and other alpha-proteobacteria to control iron-dependent gene expression. bradyrhizobium japonicum senses iron through the status of heme biosynthesis to regulate gene expression, thus it responds to an iron-dependent process rather than to iron directly. irr mediates this ... | 2009 | 19093075 |
| heme-dependent metalloregulation by the iron response regulator (irr) protein in rhizobium and other alpha-proteobacteria. | perception and response to nutritional iron by bacteria is essential for viability, and for the ability to adapt to the environment. the iron response regulator (irr) is part of a novel regulatory scheme employed by rhizobium and other alpha-proteobacteria to control iron-dependent gene expression. bradyrhizobium japonicum senses iron through the status of heme biosynthesis to regulate gene expression, thus it responds to an iron-dependent process rather than to iron directly. irr mediates this ... | 2009 | 19093075 |
| genetic and computational identification of a conserved bacterial metabolic module. | we have experimentally and computationally defined a set of genes that form a conserved metabolic module in the alpha-proteobacterium caulobacter crescentus and used this module to illustrate a schema for the propagation of pathway-level annotation across bacterial genera. applying comprehensive forward and reverse genetic methods and genome-wide transcriptional analysis, we (1) confirmed the presence of genes involved in catabolism of the abundant environmental sugar myo-inositol, (2) defined a ... | 2008 | 19096521 |
| a portal for rhizobial genomes: rhizogate integrates a sinorhizobium meliloti genome annotation update with postgenome data. | sinorhizobium meliloti is a symbiotic soil bacterium of the alphaproteobacterial subdivision. like other rhizobia, s. meliloti induces nitrogen-fixing root nodules on leguminous plants. this is an ecologically and economically important interaction, because plants engaged in symbiosis with rhizobia can grow without exogenous nitrogen fertilizers. the s. meliloti-medicago truncatula (barrel medic) association is an important symbiosis model. the s. meliloti genome was published in 2001, and the m ... | 2009 | 19103235 |
| a portal for rhizobial genomes: rhizogate integrates a sinorhizobium meliloti genome annotation update with postgenome data. | sinorhizobium meliloti is a symbiotic soil bacterium of the alphaproteobacterial subdivision. like other rhizobia, s. meliloti induces nitrogen-fixing root nodules on leguminous plants. this is an ecologically and economically important interaction, because plants engaged in symbiosis with rhizobia can grow without exogenous nitrogen fertilizers. the s. meliloti-medicago truncatula (barrel medic) association is an important symbiosis model. the s. meliloti genome was published in 2001, and the m ... | 2009 | 19103235 |
| characterization of a {gamma}-aminobutyric acid transport system of rhizobium leguminosarum bv. viciae 3841. | spontaneous mutants of rhizobium leguminosarum bv. viciae 3841 were isolated that grow faster than the wild type on gamma-aminobutyric acid (gaba) as the sole carbon and nitrogen source. these strains (ru1736 and ru1816) have frameshift mutations (gtsr101 and gtsr102, respectively) in a gntr-type regulator (gtsr) that result in a high rate of constitutive gaba transport. tn5 mutagenesis and quantitative reverse transcription-pcr showed that gstr regulates expression of a large operon (prl100242 ... | 2009 | 19103927 |
| characterization of a {gamma}-aminobutyric acid transport system of rhizobium leguminosarum bv. viciae 3841. | spontaneous mutants of rhizobium leguminosarum bv. viciae 3841 were isolated that grow faster than the wild type on gamma-aminobutyric acid (gaba) as the sole carbon and nitrogen source. these strains (ru1736 and ru1816) have frameshift mutations (gtsr101 and gtsr102, respectively) in a gntr-type regulator (gtsr) that result in a high rate of constitutive gaba transport. tn5 mutagenesis and quantitative reverse transcription-pcr showed that gstr regulates expression of a large operon (prl100242 ... | 2009 | 19103927 |
| rhizobia with different symbiotic efficiencies nodulate acaciella angustissima in mexico, including sinorhizobium chiapanecum sp. nov. which has common symbiotic genes with sinorhizobium mexicanum. | bacteria from nodules of the legume acaciella angustissima native to the south of mexico were characterized genetically and their nodulation and competitiveness were evaluated. phylogenetic studies derived from rpob gene sequences indicated that a. angustissima is nodulated by sinorhizobium mexicanum, rhizobium tropici, mesorhizobium plurifarium and agrobacterium tumefaciens and by bacteria related to sinorhizobium americanum, sinorhizobium terangae, rhizobium etli and rhizobium gallicum. a new ... | 2009 | 19120461 |
| rhizobia with different symbiotic efficiencies nodulate acaciella angustissima in mexico, including sinorhizobium chiapanecum sp. nov. which has common symbiotic genes with sinorhizobium mexicanum. | bacteria from nodules of the legume acaciella angustissima native to the south of mexico were characterized genetically and their nodulation and competitiveness were evaluated. phylogenetic studies derived from rpob gene sequences indicated that a. angustissima is nodulated by sinorhizobium mexicanum, rhizobium tropici, mesorhizobium plurifarium and agrobacterium tumefaciens and by bacteria related to sinorhizobium americanum, sinorhizobium terangae, rhizobium etli and rhizobium gallicum. a new ... | 2009 | 19120461 |
| remodelling of vipa/vipb tubules by clpv-mediated threading is crucial for type vi protein secretion. | the recently identified type vi secretion systems (t6ss) have a crucial function in the virulence of various proteobacteria, including the human pathogen vibrio cholerae. t6ss are encoded by a conserved gene cluster comprising approximately 15 open reading frames, mediating the appearance of hcp and vgrg proteins in cell culture supernatants. here, we analysed the function of the v. cholerae t6ss member clpv, a specialized aaa+ protein. clpv is crucial for a functional t6ss and interacts through ... | 2009 | 19131969 |
| complete genome sequence of the aerobic co-oxidizing thermophile thermomicrobium roseum. | in order to enrich the phylogenetic diversity represented in the available sequenced bacterial genomes and as part of an "assembling the tree of life" project, we determined the genome sequence of thermomicrobium roseum dsm 5159. t. roseum dsm 5159 is a red-pigmented, rod-shaped, gram-negative extreme thermophile isolated from a hot spring that possesses both an atypical cell wall composition and an unusual cell membrane that is composed entirely of long-chain 1,2-diols. its genome is composed o ... | 2009 | 19148287 |
| identification of undecaprenyl phosphate-beta-d-galactosamine in francisella novicida and its function in lipid a modification. | francisella tularensis is a highly infectious pathogen that causes tularemia. francisella lipid a contains an unusual galactosamine (galn) unit, attached to its 1-phosphate moiety. two genes, flmf2 and flmk, are required for the addition of galn to francisella lipid a, but the relevant enzymes and the galn donor substrate have not been characterized. we now report the purification and identification of a novel minor lipid from francisella novicida that functions as the galn donor. on the basis o ... | 2009 | 19166327 |
| roles of agrobacterium tumefaciens rira in iron regulation, oxidative stress response, and virulence. | the analysis of genetics and physiological functions of agrobacterium tumefaciens rira (rhizobial iron regulator) has shown that it is a transcription regulator and a repressor of iron uptake systems. the rira mutant strain (ntlrira) overproduced siderophores and exhibited a highly constitutive expression of genes involved in iron uptake (fhua, irp6a, and fbpa) compared to that of the wild-type strain (ntl4). the deregulation in the iron control of iron uptake in ntlrira led to iron overload in ... | 2009 | 19168612 |
| changes in barotolerance, thermotolerance, and cellular morphology throughout the life cycle of listeria monocytogenes. | changes in barotolerance, thermotolerance, and cellular morphology throughout the life cycle of listeria monocytogenes were investigated. for part 1 of this analysis, l. monocytogenes atcc 19115 was grown to log, stationary, death, and long-term-survival phases at 35 degrees c in tryptic soy broth with yeast extract (tsbye). cells were diluted in whole milk that had been subjected to ultrahigh temperatures (uht whole milk) and then high-pressure processed (hpp) at 400 mpa for 180 s or thermally ... | 2009 | 19168646 |
| the metal-dependent regulators fura and furb from mycobacterium tuberculosis. | the ferric uptake regulators (fur) form a large family of bacterial metal-activated dna-binding proteins that control a diverse set of genes at the transcriptional level. mycobacterium tuberculosis, the causative agent of tuberculosis, expresses two members of the fur family, designated fura and furb. although both belong to the same family, they share only approximately 25% sequence identity and as a consequence, they differ significantly in some of their key biological functions. fura appears ... | 2008 | 19169435 |
| the temperature-sensitive brush mutant of the legume lotus japonicus reveals a link between root development and nodule infection by rhizobia. | the brush mutant of lotus japonicus exhibits a temperature-dependent impairment in nodule, root, and shoot development. at 26 degrees c, brush formed fewer nodules, most of which were not colonized by rhizobia bacteria. primary root growth was retarded and the anatomy of the brush root apical meristem revealed distorted cellular organization and reduced cell expansion. reciprocal grafting of brush with wild-type plants indicated that this genotype only affected the root and that the shoot phenot ... | 2009 | 19176723 |
| pathway of gamma-aminobutyrate metabolism in rhizobium leguminosarum 3841 and its role in symbiosis. | pea plants incubated in 15n2 rapidly accumulated labeled gamma-aminobutyrate (gaba) in the plant cytosol and in bacteroids of rhizobium leguminosarum bv. viciae 3841. two pathways of gaba metabolism were identified in r. leguminosarum 3841. in the first, glutamate is formed by gaba aminotransferase (gabt), transferring the amino group from gaba to 2-oxoglutarate. in the second, alanine is formed by two omega-aminotransferases (opaa and opab), transferring the amino group from gaba to pyruvate. w ... | 2009 | 19181799 |
| role of potassium uptake systems in sinorhizobium meliloti osmoadaptation and symbiotic performance. | stimulation of potassium uptake is the most rapid response to an osmotic upshock in bacteria. this cation accumulates by a number of different transport systems whose importance has not been previously addressed for rhizobia. in silico analyses reveal the presence of genes encoding four possible potassium uptake systems in the genome of sinorhizobium meliloti 1021: kup1, kup2, trk, and kdp. the study of the relevance of these systems under a number of different growth conditions and in symbiosis ... | 2009 | 19181803 |
| high abundance of virulence gene homologues in marine bacteria. | marine bacteria can cause harm to single-celled and multicellular eukaryotes. however, relatively little is known about the underlying genetic basis for marine bacterial interactions with higher organisms. we examined whole-genome sequences from a large number of marine bacteria for the prevalence of homologues to virulence genes and pathogenicity islands known from bacteria that are pathogenic to terrestrial animals and plants. as many as 60 out of 119 genomes of marine bacteria, with no known ... | 2009 | 19207573 |
| comparative genomic analyses of nickel, cobalt and vitamin b12 utilization. | nickel (ni) and cobalt (co) are trace elements required for a variety of biological processes. ni is directly coordinated by proteins, whereas co is mainly used as a component of vitamin b12. although a number of ni and co-dependent enzymes have been characterized, systematic evolutionary analyses of utilization of these metals are limited. | 2009 | 19208259 |
| the time course of the transcriptomic response of sinorhizobium meliloti 1021 following a shift to acidic ph. | the symbiotic soil bacterium sinorhizobium meliloti often has to face low ph in its natural habitats. to identify genes responding to ph stress a global transcriptional analysis of s. meliloti strain 1021 following a ph shift from ph 7.0 to ph 5.75 was carried out. in detail, oligo-based whole genome microarrays were used in a time course experiment. the monitoring period covered a time span of about one hour after the ph shift. the obtained microarray data was filtered and grouped by k-means cl ... | 2009 | 19216801 |
| two small c-type cytochromes affect virulence gene expression in bacillus anthracis. | regulated expression of the genes for anthrax toxin proteins is essential for the virulence of the pathogenic bacterium bacillus anthracis. induction of toxin gene expression depends on several factors, including temperature, bicarbonate levels, and metabolic state of the cell. to identify factors that regulate toxin expression, transposon mutagenesis was performed under non-inducing conditions and mutants were isolated that untimely expressed high levels of toxin. a number of these mutations cl ... | 2009 | 19222757 |
| distinct and essential morphogenic functions for wall- and lipo-teichoic acids in bacillus subtilis. | teichoic acids (tas) are anionic polymers that constitute a major component of the cell wall in most gram-positive bacteria. despite decades of study, their function has remained unclear. tas are covalently linked either to the cell wall peptidoglycan (wall ta (wta)) or to the membrane (lipo-ta (lta)). we have characterized the key enzyme of lta synthesis in bacillus subtilis, lta synthase (ltas). we show that lta is needed for divalent cation homoeostasis and that its absence has severe effects ... | 2009 | 19229300 |
| [effects of natural and hybrid lectins on the legume-rhizobium interactions]. | the effects of hybrid lectins--full-sized pea pisum sativum lectin (psl) with the carbohydrate-binding region of white melilot melilotus albus lectin or wild licorice astragalus glycyphyllos lectin substituted for the corresponding psl region (psl/mal and psl/agl, correspondingly)--on the legume-rhizobium symbiosis were studied. the treatment of the rhizobium leguminosarum bv. viciae in the alfalfa (medicago sativa) rhizosphere with psl induced formation of uninfected pseudonodules on its roots, ... | 2009 | 19235514 |
| uridine-based inhibitors as new leads for antibiotics targeting escherichia coli lpxc. | the udp-3-o-(r-3-hydroxyacyl)-n-acetylglucosamine deacetylase lpxc catalyzes the committed reaction of lipid a (endotoxin) biosynthesis in gram-negative bacteria and is a validated antibiotic target. although several previously described compounds bind to the unique acyl chain binding passage of lpxc with high affinity, strategies to target the enzyme's udp-binding site have not been reported. here the identification of a series of uridine-based lpxc inhibitors is presented. the most potent exam ... | 2009 | 19256534 |
| the cin and rai quorum-sensing regulatory systems in rhizobium leguminosarum are coordinated by expr and cins, a small regulatory protein coexpressed with cini. | to understand how the rhizobium leguminosarum raii-rair quorum-sensing system is regulated, we identified mutants with decreased levels of raii-made n-acyl homoserine lactones (ahls). a luxr-type regulator, expr, is required for rair expression, and rair is required to induce raii. since rair (and raii) expression is also reduced in cini and cinr quorum-sensing mutants, we thought cini-made ahls may activate expr to induce rair. however, added cini-made ahls did not induce rair expression in a c ... | 2009 | 19270098 |
| growmatch: an automated method for reconciling in silico/in vivo growth predictions. | genome-scale metabolic reconstructions are typically validated by comparing in silico growth predictions across different mutants utilizing different carbon sources with in vivo growth data. this comparison results in two types of model-prediction inconsistencies; either the model predicts growth when no growth is observed in the experiment (gng inconsistencies) or the model predicts no growth when the experiment reveals growth (ngg inconsistencies). here we propose an optimization-based framewo ... | 2009 | 19282964 |
| diversity and transcription of proteases involved in the maturation of hydrogenases in nostoc punctiforme atcc 29133 and nostoc sp. strain pcc 7120. | the last step in the maturation process of the large subunit of [nife]-hydrogenases is a proteolytic cleavage of the c-terminal by a hydrogenase specific protease. contrary to other accessory proteins these hydrogenase proteases are believed to be specific whereby one type of hydrogenases specific protease only cleaves one type of hydrogenase. in cyanobacteria this is achieved by the gene product of either hupw or hoxw, specific for the uptake or the bidirectional hydrogenase respectively. the f ... | 2009 | 19284580 |
| characterization of the hupsl promoter activity in nostoc punctiforme atcc 29133. | in cyanobacteria three enzymes are directly involved in the hydrogen metabolism; a nitrogenase that produces molecular hydrogen, h2, as a by-product of nitrogen fixation, an uptake hydrogenase that recaptures h2 and oxidize it, and a bidirectional hydrogenase that can both oxidize and produce h2.nostoc punctiforme atcc 29133 is a filamentous dinitrogen fixing cyanobacterium containing a nitrogenase and an uptake hydrogenase but no bidirectional hydrogenase. generally, little is known about the t ... | 2009 | 19284581 |
| the mnth gene encodes the major mn(2+) transporter in bradyrhizobium japonicum and is regulated by manganese via the fur protein. | the bacterial nramp family protein mnth is a divalent metal transporter, but mnth mutants have little or no phenotype in organisms where it has been studied. here, we identify the mnth homologue of bradyrhizobium japonicum, and demonstrate that it is essential for mn(2+) transport and for maintenance of cellular manganese homeostasis. transport activity was induced under manganese deficiency, and fe(2+) did not compete with (54)mn(2+) for uptake by cells. the steady-state level of mnth mrna was ... | 2009 | 19298371 |
| indole acts as an extracellular cue regulating gene expression in vibrio cholerae. | indole has been proposed to act as an extracellular signal molecule influencing biofilm formation in a range of bacteria. for this study, the role of indole in vibrio cholerae biofilm formation was examined. it was shown that indole activates genes involved in vibrio polysaccharide (vps) production, which is essential for v. cholerae biofilm formation. in addition to activating these genes, it was determined using microarrays that indole influences the expression of many other genes, including t ... | 2009 | 19329638 |
| structural basis for the specialization of nur, a nickel-specific fur homolog, in metal sensing and dna recognition. | nur, a member of the fur family, is a nickel-responsive transcription factor that controls nickel homeostasis and anti-oxidative response in streptomyces coelicolor. here we report the 2.4-a resolution crystal structure of nur. it contains a unique nickel-specific metal site in addition to a nonspecific common metal site. the identification of the 6-5-6 motif of the nur recognition box and a nur/dna complex model reveals that nur mainly interacts with terminal bases of the palindrome on complex ... | 2009 | 19336416 |
| sequence-specific binding to a subset of iscr-regulated promoters does not require iscr fe-s cluster ligation. | iscr is an fe-s protein that functions as a transcriptional regulator of fe-s biogenesis and other fe-s protein-encoding genes in escherichia coli. in this study, we investigated the requirement for the ligation of the [2fe-2s] cluster of iscr to regulate a subset of iscr target promoters (p(hyaa), p(ydiu), p(napf), and p(hybo)) and defined the requirements for sequence-specific binding to the iscr target site in the hyaa promoter region. in contrast to previous results with the iscr promoter, w ... | 2009 | 19361432 |
| identification and characterization of hemolysin-like proteins similar to rtx toxin in pasteurella pneumotropica. | pasteurella pneumotropica is an opportunistic pathogen that causes lethal pneumonia in immunodeficient rodents. the virulence factors of this bacterium remain unknown. in this study, we identified the genes encoding two rtx toxins, designated as pnxi and pnxii, from the genomic dna of p. pneumotropica atcc 35149 and characterized with respect to hemolysis. the pnxi operon was organized according to the manner in which the genes encoded the structural rtx toxin (pnxia), the type i secretion syste ... | 2009 | 19363112 |