| bioluminescence imaging of clavibacter michiganensis subsp. michiganensis infection of tomato seeds and plants. | clavibacter michiganensis subsp. michiganensis is a gram-positive bacterium that causes wilting and cankers, leading to severe economic losses in commercial tomato production worldwide. the disease is transmitted from infected seeds to seedlings and mechanically from plant to plant during seedling production, grafting, pruning, and harvesting. because of the lack of tools for genetic manipulation, very little is known regarding the mechanisms of seed and seedling infection and movement of c. mic ... | 2010 | 20400561 |
| phenolic acids act as signaling molecules in plant-microbe symbioses. | phenolic acids are the main polyphenols made by plants. these compounds have diverse functions and are immensely important in plant-microbe interactions/symbiosis. phenolic compounds act as signaling molecules in the initiation of legumerhizobia symbioses, establishment of arbuscular mycorrhizal symbioses and can act as agents in plant defense. flavonoids are a diverse class of polyphenolic compounds that have received considerable attention as signaling molecules involved in plant-microbe inter ... | 2010 | 20400851 |
| autoinducer-2 and qsec control biofilm formation and in vivo virulence of aggregatibacter actinomycetemcomitans. | biofilm formation by the periodontal pathogen aggregatibacter actinomycetemcomitans is dependent upon autoinducer-2 (ai-2)-mediated quorum sensing. however, the components that link the detection of the ai-2 signal to downstream gene expression have not been determined. one potential regulator is the qsebc two-component system, which is part of the ai-2-dependent response pathway that controls biofilm formation in escherichia coli. here we show that the expression of qsebc in a. actinomycetemcom ... | 2010 | 20404080 |
| a pathobiont of the microbiota balances host colonization and intestinal inflammation. | the gastrointestinal tract harbors a diverse microbiota that has coevolved with mammalian hosts. though most associations are symbiotic or commensal, some resident bacteria (termed pathobionts) have the potential to cause disease. bacterial type vi secretion systems (t6sss) are one mechanism for forging host-microbial interactions. here we reveal a protective role for the t6ss of helicobacter hepaticus, a gram-negative bacterium of the intestinal microbiota. h. hepaticus mutants with a defective ... | 2010 | 20413095 |
| characterization of strains unlike mesorhizobium loti that nodulate lotus spp. in saline soils of granada, spain. | lotus species are forage legumes with potential as pastures in low-fertility and environmentally constrained soils, owing to their high persistence and yield under those conditions. the aim of this work was the characterization of phenetic and genetic diversity of salt-tolerant bacteria able to establish efficient symbiosis with lotus spp. a total of 180 isolates able to nodulate lotus corniculatus and lotus tenuis from two locations in granada, spain, were characterized. molecular identificatio ... | 2010 | 20435777 |
| characterization of the nifa-rpon regulon in rhizobium etli in free life and in symbiosis with phaseolus vulgaris. | the nifa-rpon complex is a master regulator of the nitrogen fixation genes in alphaproteobacteria. based on the complete rhizobium etli genome sequence, we constructed an r. etli cfn42 oligonucleotide (70-mer) microarray and utilized this tool, reverse transcription (rt)-pcr analysis (transcriptomics), proteomics, and bioinformatics to decipher the nifa-rpon regulon under microaerobic conditions (free life) and in symbiosis with bean plants. the r. etli nifa-rpon regulon was determined to contai ... | 2010 | 20453139 |
| disruption of the glycine cleavage system enables sinorhizobium fredii usda257 to form nitrogen-fixing nodules on agronomically improved north american soybean cultivars. | the symbiosis between sinorhizobium fredii usda257 and soybean [glycine max (l.) merr.] exhibits a high degree of cultivar specificity. usda257 nodulates primitive soybean cultivars but fails to nodulate agronomically improved cultivars such as mccall. in this study we provide evidence for the involvement of a new genetic locus that controls soybean cultivar specificity. this locus was identified in usda257 by tn5 transposon mutagenesis followed by nodulation screening on mccall soybean. we have ... | 2010 | 20453144 |
| characterization of swarming motility in rhizobium leguminosarum bv. viciae. | we have characterized swarming motility in rhizobium leguminosarum strains 3841 and vf39sm. swarming was dependent on growth on energy-rich media, and both agar concentration and incubation temperature were critical parameters for surface migration. a cell density-dependent lag period was observed before swarming motility was initiated. surface migration began 3-5 days after inoculation and a full swarming phenotype was observed 3 weeks after inoculation. the swarming front was preceded by a cle ... | 2010 | 20455952 |
| heterologous expression and maturation of an nadp-dependent [nife]-hydrogenase: a key enzyme in biofuel production. | hydrogen gas is a major biofuel and is metabolized by a wide range of microorganisms. microbial hydrogen production is catalyzed by hydrogenase, an extremely complex, air-sensitive enzyme that utilizes a binuclear nickel-iron [nife] catalytic site. production and engineering of recombinant [nife]-hydrogenases in a genetically-tractable organism, as with metalloprotein complexes in general, has met with limited success due to the elaborate maturation process that is required, primarily in the abs ... | 2010 | 20463892 |
| genetic and metabolic divergence within a rhizobium leguminosarum bv. trifolii population recovered from clover nodules. | rhizobia are able to establish symbiosis with leguminous plants and usually occupy highly complex soil habitats. the large size and complexity of their genomes are considered advantageous, possibly enhancing their metabolic and adaptive potential and, in consequence, their competitiveness. a population of rhizobium leguminosarum bv. trifolii organisms recovered from nodules of several clover plants growing in each other's vicinity in the soil was examined regarding possible relationships between ... | 2010 | 20472725 |
| burkholderia phymatum strains capable of nodulating phaseolus vulgaris are present in moroccan soils. | phylogenetic analysis of 16s rrna, nodc, and nifh genes of four bacterial strains isolated from root nodules of phaseolus vulgaris grown in morocco soils were identified as burkholderia phymatum. all four strains formed n(2)-fixing nodules on p. vulgaris and mimosa, acacia, and prosopis species and reduced acetylene to ethylene when cultured ex planta. | 2010 | 20472732 |
| enzymatic total synthesis of rabelomycin, an angucycline group antibiotic. | a one-pot enzymatic total synthesis of angucycline antibiotic rabelomycin was accomplished, starting from acetyl-coa and malonyl-coa, using a mixture of polyketide synthase (pks) enzymes of the gilvocarcin, ravidomycin, and jadomycin biosynthetic pathways. the in vitro results were compared to in vivo catalysis using analogous sets of enzymes. | 2010 | 20486694 |
| feun, a novel modulator of two-component signalling identified in sinorhizobium meliloti. | sinorhizobium meliloti is a nitrogen-fixing bacterial symbiont of alfalfa and related legumes. symbiotic infection by s. meliloti requires an osmosensory two-component system composed of the response regulator feup and the sensor kinase feuq. the feupq pathway positively regulates transcription of multiple genes including ndva, which encodes the cyclic glucan exporter. here we show that proper regulation of this signalling pathway is essential for cell viability. without the small 83 amino acid ... | 2010 | 20487268 |
| nooks and crannies in type vi secretion regulation. | type vi secretion systems (t6ss) are macromolecular, transenvelope machines encoded within the genomes of most gram-negative bacteria, including plant, animal, and human pathogens, as well as soil and environmental isolates. t6ss are involved in a broad variety of functions: from pathogenesis to biofilm formation and stress sensing. this large array of functions is reflected by a vast diversity of regulatory mechanisms: repression by histone-like proteins and regulation by quorum sensing, transc ... | 2010 | 20511495 |
| population mixing of rhizobium leguminosarum bv. viciae nodulating vicia faba: the role of recombination and lateral gene transfer. | the level and mechanisms of population mixing among faba bean (vicia faba) rhizobia of different geographic origins (three ecoregions of china and several western countries) were analysed by sequencing three chromosomal housekeeping loci (atpd, reca and glnii) and one nodulation gene (nodd). eight distinct sublineages of rhizobium leguminosarum bv. viciae (rlv) were identified by concatenated sequences of chromosomal loci. structure analysis revealed admixture patterns of rlv populations of diff ... | 2010 | 20533948 |
| enhancement of the nitrogen fixation efficiency of genetically-engineered rhizobium with high catalase activity. | the vkta catalase gene, which had been cloned from vibrio rumoiensis s-1t having extraordinarily high catalase activity, was introduced into the root nodule bacterium, rhizobium leguminosarum bv. phaseoli usda 2676. the catalase activity of the vkta-transformed r. leguminosarum cells (free-living) was three orders in magnitude higher than that of the parent cells and this transformant could grow in a higher concentration of exogenous hydrogen peroxide (h2o2). the vkta-transformant was inoculated ... | 2010 | 20547375 |
| deletion of a fur-like gene affects iron homeostasis and magnetosome formation in magnetospirillum gryphiswaldense. | magnetotactic bacteria synthesize specific organelles, the magnetosomes, which are membrane-enveloped crystals of the magnetic mineral magnetite (fe(3)o(4)). the biomineralization of magnetite involves the uptake and intracellular accumulation of large amounts of iron. however, it is not clear how iron uptake and biomineralization are regulated and balanced with the biochemical iron requirement and intracellular homeostasis. in this study, we identified and analyzed a homologue of the ferric upt ... | 2010 | 20562310 |
| transcriptional control of the bradyrhizobium japonicum irr gene requires repression by fur and antirepression by irr. | bradyrhizobium japonicum fur mediates manganese-responsive transcriptional control of the mnth gene independently of iron, but it also has been implicated in iron-dependent regulation of the irr gene. thus, we sought to address the apparent discrepancy in fur responsiveness to metals. irr is a transcriptional regulator found in iron-limited cells. here, we show that irr gene mrna was regulated by both iron and manganese, and repression occurred only in the presence of both metals. under these co ... | 2010 | 20573962 |
| agrobacterium tumefaciens exor represses succinoglycan biosynthesis and is required for biofilm formation and motility. | the ubiquitous plant pathogen agrobacterium tumefaciens attaches efficiently to plant tissues and abiotic surfaces and can form complex biofilms. a genetic screen for mutants unable to form biofilms on pvc identified disruptions in a homologue of the exor gene. exor is a predicted periplasmic protein, originally identified in sinorhizobium meliloti, but widely conserved among alphaproteobacteria. disruptions in the a. tumefaciens exor gene result in severely compromised attachment to abiotic sur ... | 2010 | 20576688 |
| an alternative route for udp-diacylglucosamine hydrolysis in bacterial lipid a biosynthesis. | the outer leaflet of the outer membranes of gram-negative bacteria is composed primarily of lipid a, the hydrophobic anchor of lipopolysaccharide. like escherichia coli, most gram-negative bacteria encode one copy of each of the nine genes required for lipid a biosynthesis. an important exception exists in the case of the fourth enzyme, lpxh, a peripheral membrane protein that hydrolyzes udp-2,3-diacylglucosamine to form 2,3-diacylglucosamine 1-phosphate and ump by catalyzing the attack of water ... | 2010 | 20608695 |
| a conserved mechanism of gaba binding and antagonism is revealed by structure-function analysis of the periplasmic binding protein atu2422 in agrobacterium tumefaciens. | bacterial periplasmic binding proteins (pbps) and eukaryotic pbp-like domains (also called as venus flytrap modules) of g-protein-coupled receptors are involved in extracellular gaba perception. we investigated the structural and functional basis of ligand specificity of the pbp atu2422, which is implicated in virulence and transport of gaba in the plant pathogen agrobacterium tumefaciens. five high-resolution x-ray structures of atu2422 liganded to gaba, pro, ala, and val and of point mutant at ... | 2010 | 20630861 |
| characterization and pcr-based replicon typing of resistance plasmids in acinetobacter baumannii. | acinetobacter baumannii is an opportunistic pathogen, especially in intensive care units, and multidrug-resistant isolates have increasingly been reported during the last decade. despite recent progress in knowledge of antibiotic resistance mechanisms in a. baumannii, little is known about the genetic factors driving isolates toward multidrug resistance. in the present study, the a. baumannii plasmids were investigated through the analysis and classification of plasmid replication systems and th ... | 2010 | 20660691 |
| a two-component kdo hydrolase in the inner membrane of francisella novicida. | lipid a coats the outer surface of the outer membrane of gram-negative bacteria. in francisella tularensis subspecies novicida lipid a is present either as the covalently attached anchor of lipopolysaccharide (lps) or as free lipid a. the lipid a moiety of francisella lps is linked to the core domain by a single 2-keto-3-deoxy-d-manno-octulosonic acid (kdo) residue. f. novicida kdta is bi-functional, but f. novicida contains a membrane-bound kdo hydrolase that removes the outer kdo unit. the hyd ... | 2010 | 20662782 |
| evolutionary dynamics of insertion sequences in relation to the evolutionary histories of the chromosome and symbiotic plasmid genes of rhizobium etli populations. | insertion sequences (is) are mobile genetic elements that are distributed in many prokaryotes. in particular, in the genomes of the symbiotic nitrogen-fixing bacteria collectively known as rhizobia, is are fairly abundant in plasmids or chromosomal islands that carry the genes needed for symbiosis. here, we report an analysis of the distribution and genetic conservation of the is found in the genome of rhizobium etli cfn42 in a collection of 87 rhizobium strains belonging to populations with dif ... | 2010 | 20675442 |
| pyruvate is synthesized by two pathways in pea bacteroids with different efficiencies for nitrogen fixation. | nitrogen fixation in legume bacteroids is energized by the metabolism of dicarboxylic acids, which requires their oxidation to both oxaloacetate and pyruvate. in alfalfa bacteroids, production of pyruvate requires nad+ malic enzyme (dme) but not nadp+ malic enzyme (tme). however, we show that rhizobium leguminosarum has two pathways for pyruvate formation from dicarboxylates catalyzed by dme and by the combined activities of phosphoenolpyruvate (pep) carboxykinase (pcka) and pyruvate kinase (pyk ... | 2010 | 20675477 |
| bathy phytochromes in rhizobial soil bacteria. | phytochromes are biliprotein photoreceptors that are found in plants, bacteria, and fungi. prototypical phytochromes have a pr ground state that absorbs in the red spectral range and is converted by light into the pfr form, which absorbs longer-wavelength, far-red light. recently, some bacterial phytochromes have been described that undergo dark conversion of pr to pfr and thus have a pfr ground state. we show here that such so-called bathy phytochromes are widely distributed among bacteria that ... | 2010 | 20675484 |
| contribution of porphyromonas gingivalis lipopolysaccharide to periodontitis. | | 2010 | 20712633 |
| characterization and functional analysis of seven flagellin genes in rhizobium leguminosarum bv. viciae. characterization of r. leguminosarum flagellins. | rhizobium leguminosarum bv. viciae establishes symbiotic nitrogen fixing partnerships with plant species belonging to the tribe vicieae, which includes the genera vicia, lathyrus, pisum and lens. motility and chemotaxis are important in the ecology of r. leguminosarum to provide a competitive advantage during the early steps of nodulation, but the mechanisms of motility and flagellar assembly remain poorly studied. this paper addresses the role of the seven flagellin genes in producing a functio ... | 2010 | 20716375 |
| phaseolus vulgaris is nodulated in northern spain by rhizobium leguminosarum strains harboring two nodc alleles present in american rhizobium etli strains: biogeographical and evolutionary implications. | in this study a collection of rhizobial strains were isolated from effective nodules of phaseolus vulgaris in a wide region of northern spain, which is the major producer region of this legume in spain. the analysis of their core genes, rrs, atpd, and reca, and the 16s-23s intergenic spacer showed that all isolates belong to the phylogenetic group of rhizobium leguminosarum and some of them were identical to those of strains nodulating vicia or trifolium. none of the isolates was identified as r ... | 2010 | 20725128 |
| flavonoid-induced calcium signalling in rhizobium leguminosarum bv. viciae. | • legume-rhizobium symbiosis requires a complex dialogue based on the exchange of diffusible signals between the partners. compatible rhizobia express key nodulation (nod) genes in response to plant signals - flavonoids - before infection. host plants sense counterpart rhizobial signalling molecules - nod factors - through transient changes in intracellular free-calcium. here we investigate the potential involvement of ca(2+) in the symbiotic signalling pathway activated by flavonoids in rhizobi ... | 2010 | 20738787 |
| escherichia coli mutants that synthesize dephosphorylated lipid a molecules. | the lipid a moiety of escherichia coli lipopolysaccharide is a hexaacylated disaccharide of glucosamine that is phosphorylated at the 1 and 4' positions. expression of the francisella novicida lipid a 1-phosphatase fnlpxe in e. coli results in dephosphorylation of the lipid a proximal unit. coexpression of fnlpxe and the rhizobium leguminosarum lipid a oxidase rllpxq in e. coli converts much of the proximal glucosamine to 2-amino-2-deoxygluconate. expression of the f. novicida lipid a 4'-phospha ... | 2010 | 20795687 |
| mobility of plasmids. | plasmids are key vectors of horizontal gene transfer and essential genetic engineering tools. they code for genes involved in many aspects of microbial biology, including detoxication, virulence, ecological interactions, and antibiotic resistance. while many studies have decorticated the mechanisms of mobility in model plasmids, the identification and characterization of plasmid mobility from genome data are unexplored. by reviewing the available data and literature, we established a computation ... | 2010 | 20805406 |
| structures of the lipopolysaccharides from rhizobium leguminosarum rbl5523 and its udp-glucose dehydrogenase mutant (exo5). | rhizobial lipopolysaccharide (lps) is required to establish an effective symbiosis with its host plant. an exo5 mutant of rhizobium leguminosarum rbl5523, strain rbl5808, is defective in udp-glucose (glc) dehydrogenase that converts udp-glc to udp-glucuronic acid (glca). this mutant is unable to synthesize either udp-glca or udp-galacturonic acid (gala) and is unable to synthesize extracellular and capsular polysaccharides, lacks gala in its lps and is defective in symbiosis (laus mc, logman tj, ... | 2011 | 20817634 |
| structures of the lipopolysaccharides from rhizobium leguminosarum rbl5523 and its udp-glucose dehydrogenase mutant (exo5). | rhizobial lipopolysaccharide (lps) is required to establish an effective symbiosis with its host plant. an exo5 mutant of rhizobium leguminosarum rbl5523, strain rbl5808, is defective in udp-glucose (glc) dehydrogenase that converts udp-glc to udp-glucuronic acid (glca). this mutant is unable to synthesize either udp-glca or udp-galacturonic acid (gala) and is unable to synthesize extracellular and capsular polysaccharides, lacks gala in its lps and is defective in symbiosis (laus mc, logman tj, ... | 2011 | 20817634 |
| characterization of a two-component regulatory system that regulates succinate-mediated catabolite repression in sinorhizobium meliloti. | when they are available, sinorhizobium meliloti utilizes c(4)-dicarboxylic acids as preferred carbon sources for growth while suppressing the utilization of some secondary carbon sources such as α- and β-galactosides. the phenomenon of using succinate as the sole carbon source in the presence of secondary carbon sources is termed succinate-mediated catabolite repression (smcr). genetic screening identified the gene sma0113 as needed for strong smcr when s. meliloti was grown in succinate plus la ... | 2010 | 20817764 |
| membrane topology mapping of the o-antigen flippase (wzx), polymerase (wzy), and ligase (waal) from pseudomonas aeruginosa pao1 reveals novel domain architectures. | biosynthesis of b-band lipopolysaccharide (lps) in pseudomonas aeruginosa follows the wzy-dependent pathway, requiring the integral inner membrane proteins wzx (o-antigen [o-ag] flippase), wzy (o-ag polymerase), and waal (o-ag ligase). for an important first step in deciphering the mechanisms of lps assembly, we set out to map the membrane topology of these proteins. random and targeted 3'wzx, wzy, and waal truncations were fused to a phoa-laczalpha dual reporter capable of displaying both alkal ... | 2010 | 20824106 |
| comparing symbiotic efficiency between swollen versus nonswollen rhizobial bacteroids. | symbiotic rhizobia differentiate physiologically and morphologically into nitrogen-fixing bacteroids inside legume host nodules. the differentiation is apparently terminal in some legume species, such as peas (pisum sativum) and peanuts (arachis hypogaea), likely due to extreme cell swelling induced by the host. in other legume species, such as beans (phaseolus vulgaris) and cowpeas (vigna unguiculata), differentiation into bacteroids, which are similar in size and shape to free-living rhizobia, ... | 2010 | 20837702 |
| symbiotic legume nodules employ both rhizobial exo- and endo-hydrogenases to recycle hydrogen produced by nitrogen fixation. | in symbiotic legume nodules, endosymbiotic rhizobia (bacteroids) fix atmospheric n(2), an atp-dependent catalytic process yielding stoichiometric ammonium and hydrogen gas (h(2)). while in most legume nodules this h(2) is quantitatively evolved, which loss drains metabolic energy, certain bacteroid strains employ uptake hydrogenase activity and thus evolve little or no h(2). rather, endogenous h(2) is efficiently respired at the expense of o(2), driving oxidative phosphorylation, recouping atp u ... | 2010 | 20838423 |
| biosynthesis of udp-xylose and udp-arabinose in sinorhizobium meliloti 1021: first characterization of a bacterial udp-xylose synthase, and udp-xylose 4-epimerase. | sinorhizobium meliloti is a soil bacterium that fixes nitrogen after being established inside nodules that can form on the roots of several legumes, including medicago truncatula. a mutation in an s. meliloti gene (lpsb) required for lipopolysaccharide synthesis has been reported to result in defective nodulation and an increase in the synthesis of a xylose-containing glycan. glycans containing xylose as well as arabinose are also formed by other rhizobial species, but little is known about thei ... | 2011 | 20847005 |
| genotypic and phenotypic diversity of rhizobia isolated from lathyrus japonicus indigenous to japan. | sixty-one rhizobial strains from lathyrus japonicus nodules growing on the seashore in japan were characterized and compared to two strains from canada. the pcr-based method was used to identify test strains with novel taxonomic markers that were designed to discriminate between all known lathyrus rhizobia. three genomic groups (i, ii, and iii) were finally identified using rapd, rflp, and phylogenetic analyses. strains in genomic group i (related to rhizobium leguminosarum) were divided into tw ... | 2010 | 20851546 |
| engineered polyketide biosynthesis and biocatalysis in escherichia coli. | polyketides are important bioactive natural products biosynthesized by bacteria, fungi, and plants. the enzymes that synthesize polyketides are collectively referred to as polyketide synthases (pkss). because many of the natural hosts that produce polyketides are difficult to culture or manipulate, establishing a universal heterologous host that is genetically tractable has become an important goal toward the engineered biosynthesis of polyketides and analogues. here, we summarize the recent pro ... | 2010 | 20853106 |
| complete genome and comparative analysis of the chemolithoautotrophic bacterium oligotropha carboxidovorans om5. | oligotropha carboxidovorans om5 t. (dsm 1227, atcc 49405) is a chemolithoautotrophic bacterium capable of utilizing co (carbon monoxide) and fixing co2 (carbon dioxide). we previously published the draft genome of this organism and recently submitted the complete genome sequence to genbank. | 2010 | 20863402 |
| membrane topology and identification of critical amino acid residues in the wzx o-antigen translocase from escherichia coli o157:h4. | wzx belongs to a family of membrane proteins involved in the translocation of isoprenoid lipid-linked glycans, which is loosely related to members of the major facilitator superfamily. despite wzx homologs performing a conserved function, it has been difficult to pinpoint specific motifs of functional significance in their amino acid sequences. here, we elucidate the topology of the escherichia coli o157 wzx (wzx(eco157)) by a combination of bioinformatics and substituted cysteine scanning mutag ... | 2010 | 20870764 |
| [the nadph oxidase activity of pea seedling roots in rhizobial infection depending on abiotic and biotic factors]. | the changes in nadph activity was studied in the roots of 3-4-day-old etiolated pea (cultivar aksaiskii usatyi) seedlings depending on plant inoculation with rhizobium leguminosarum bv. viceae (strain ciam 1026), adverse environmental factors (low temperature and high dose of a mineral nitrogen fertilizer), chemical substances (sodium nitroprusside and methyl viologen, or paraquat), and a biotic factor--the bacterium escherichia coli (strain xl-1 blue). it was demonstrated that all exogenous fac ... | 2010 | 20873175 |
| evolution and multiplicity of arginine decarboxylases in polyamine biosynthesis and essential role in bacillus subtilis biofilm formation. | arginine decarboxylases (adcs; ec 4.1.1.19) from four different protein fold families are important for polyamine biosynthesis in bacteria, archaea, and plants. biosynthetic alanine racemase fold (ar-fold) adc is widespread in bacteria and plants. we report the discovery and characterization of an ancestral form of the ar-fold adc in the bacterial chloroflexi and bacteroidetes phyla. the ancestral ar-fold adc lacks a large insertion found in escherichia coli and plant ar-fold adc and is more sim ... | 2010 | 20876533 |
| α-aminoadipic acid and α,ɛ-diaminopimelic acid in inoculated pea plants (pisum sativum) and root nodule bacteria (rhizobium leguminosarum). | observations were made on the content of α-aminoadipic acid and α-aminophimelic acid (dap) in pea plants, nodules and rhizobium leguminosarum, strain ht3. the preparations were purified by ion exchange chromatography, qualitative analyses were made by paper chromatography, and quantitative analyses by means of an automatic amino acid analysator. in the whole plant and seeds the content of α-aminoadipic acid soluble in 70% ethanol varied between 10 and 80 μg/g dry weight. the shoot and red nitrog ... | 1969 | 20925682 |
| the extracellular proteome of rhizobium etli ce3 in exponential and stationary growth phase. | abstract: | 2010 | 20942974 |
| what is type vi secretion doing in all those bugs? | the identification of bacterial secretion systems capable of translocating substrates into eukaryotic cells via needle-like appendages has opened fruitful and exciting areas of microbial pathogenesis research. the recent discovery of the type vi secretion system (t6ss) was met with early speculation that it too acts as a 'needle' that pathogens aim at host cells. new reports demonstrate that certain t6sss are potent mediators of interbacterial interactions. in light of these findings, we examine ... | 2010 | 20961764 |
| studies on lyophiled cultures; lyophile storage of cultures of rhizobium leguminosarum. | | 1946 | 20995934 |
| n-acylation during glidobactin biosynthesis by the tridomain nonribosomal peptide synthetase module glbf. | glidobactins are hybrid nrps-pks natural products that function as irreversible proteasome inhibitors. a variety of medium chain 2(e),4(e)-diene fatty acids n-acylate the peptidolactam core and contribute significantly to the potency of proteasome inhibition. we have expressed the initiation nrps module glbf (c-a-t) in escherichia coli and observe soluble active protein only on coexpression with the 8 kda mbth-like protein, glbe. following adenylation and installation of thr as a t-domain thioes ... | 2010 | 21035730 |
| rhizobium leguminosarum bv. trifolii rosr is required for interaction with clover, biofilm formation and adaptation to the environment. | rhizobium leguminosarum bv. trifolii is a symbiotic nitrogen-fixing bacterium that elicits nodules on roots of host plants trifolium spp. bacterial surface polysaccharides are crucial for establishment of a successful symbiosis with legumes that form indeterminate-type nodules, such as trifolium, pisum, vicia, and medicago spp. and aid the bacterium in withstanding osmotic and other environmental stresses. recently, the r. leguminosarum bv. trifolii rosr regulatory protein which controls exopoly ... | 2010 | 21070666 |
| characterisation of source-separated household waste intended for composting. | large-scale composting of source-separated household waste has expanded in recent years in the nordic countries. one problem can be low ph at the start of the process. incoming biowaste at four composting plants was characterised chemically, physically and microbiologically. the ph of food waste ranged from 4.7 to 6.1 and organic acid concentration from 24 to 81 mmol kg(-1). the bacterial diversity in the waste samples was high, with all samples dominated by gammaproteobacteria, particularly pse ... | 2010 | 21075618 |
| role of symbiotic auxotrophy in the rhizobium-legume symbioses. | rhizobium leguminosarum bv. viciae mutants unable to transport branched-chain amino acids via the two main amino acid abc transport complexes aapjqmp and bradefgc produce a nitrogen starvation phenotype when inoculated on pea (pisum sativum) plants [1], [2]. bacteroids in indeterminate pea nodules have reduced abundance and a lower chromosome number. they reduce transcription of pathways for branched-chain amino acid biosynthesis and become dependent on their provision by the host. this has been ... | 2010 | 21085630 |
| o-acetylation of peptidoglycan is required for proper cell separation and s-layer anchoring in bacillus anthracis. | o-acetylation of the murnac moiety of peptidoglycan is typically associated with bacterial resistance to lysozyme, a muramidase that serves as a central component of innate immunity. here, we report that the peptidoglycan of bacillus anthracis, the etiological agent of anthrax, is o-acetylated and that, unusually, this modification is produced by two unrelated families of o-acetyltransferases. also, in contrast to other bacteria, o-acetylation of b. anthracis peptidoglycan is combined with n-dea ... | 2010 | 21135105 |
| o-acetylation of peptidoglycan is required for proper cell separation and s-layer anchoring in bacillus anthracis. | o-acetylation of the murnac moiety of peptidoglycan is typically associated with bacterial resistance to lysozyme, a muramidase that serves as a central component of innate immunity. here, we report that the peptidoglycan of bacillus anthracis, the etiological agent of anthrax, is o-acetylated and that, unusually, this modification is produced by two unrelated families of o-acetyltransferases. also, in contrast to other bacteria, o-acetylation of b. anthracis peptidoglycan is combined with n-dea ... | 2010 | 21135105 |
| a c subunit of the plant nuclear factor nf-y required for rhizobial infection and nodule development affects partner selection in the common bean-rhizobium etli symbiosis. | legume plants are able to interact symbiotically with soil bacteria to form nitrogen-fixing root nodules. although specific recognition between rhizobia and legume species has been extensively characterized, plant molecular determinants that govern the preferential colonization by different strains within a single rhizobium species have received little attention. we found that the c subunit of the heterotrimeric nuclear factor nf-y from common bean (phaseolus vulgaris) nf-yc1 plays a key role in ... | 2010 | 21139064 |
| quinone-dependent d-lactate dehydrogenase dld (cg1027) is essential for growth of corynebacterium glutamicum on d-lactate. | corynebacterium glutamicum is able to grow with lactate as sole or combined carbon and energy source. quinone-dependent l-lactate dehydrogenase lldd is known to be essential for utilization of l-lactate by c. glutamicum. d-lactate also serves as sole carbon source for c. glutamicum atcc 13032. | 2010 | 21159175 |
| species-specific and inhibitor-dependent conformations of lpxc: implications for antibiotic design. | lpxc is an essential enzyme in the lipid a biosynthetic pathway in gram-negative bacteria. several promising antimicrobial lead compounds targeting lpxc have been reported, though they typically display a large variation in potency against different gram-negative pathogens. we report that inhibitors with a diacetylene scaffold effectively overcome the resistance caused by sequence variation in the lpxc substrate-binding passage. compound binding is captured in complex with representative lpxc or ... | 2010 | 21167751 |
| species-specific and inhibitor-dependent conformations of lpxc: implications for antibiotic design. | lpxc is an essential enzyme in the lipid a biosynthetic pathway in gram-negative bacteria. several promising antimicrobial lead compounds targeting lpxc have been reported, though they typically display a large variation in potency against different gram-negative pathogens. we report that inhibitors with a diacetylene scaffold effectively overcome the resistance caused by sequence variation in the lpxc substrate-binding passage. compound binding is captured in complex with representative lpxc or ... | 2010 | 21167751 |
| cytochrome c4 is required for siderophore expression by legionella pneumophila, whereas cytochromes c1 and c5 promote intracellular infection. | a panel of cytochrome c maturation (ccm) mutants of legionella pneumophila displayed a loss of siderophore (legiobactin) expression, as measured by both the chrome azurol s assay and a legionella-specific bioassay. these data, coupled with the finding that ccm transcripts are expressed by wild-type bacteria grown in deferrated medium, indicate that the ccm system promotes siderophore expression by l. pneumophila. to determine the basis of this newfound role for ccm, we constructed and tested a s ... | 2010 | 21178169 |
| control of lipopolysaccharide biosynthesis by ftsh-mediated proteolysis of lpxc is conserved in enterobacteria but not in all gram-negative bacteria. | despite the essential function of lipopolysaccharides (lps) in gram-negative bacteria, it is largely unknown how the exact amount of this molecule in the outer membrane is controlled. the first committed step in lps biosynthesis is catalyzed by the lpxc enzyme. in escherichia coli, the cellular concentration of lpxc is adjusted by the only essential protease in this organism, the membrane-anchored metalloprotease ftsh. turnover of e. coli lpxc requires a length- and sequence-specific c-terminal ... | 2010 | 21193611 |
| control of lipopolysaccharide biosynthesis by ftsh-mediated proteolysis of lpxc is conserved in enterobacteria but not in all gram-negative bacteria. | despite the essential function of lipopolysaccharides (lps) in gram-negative bacteria, it is largely unknown how the exact amount of this molecule in the outer membrane is controlled. the first committed step in lps biosynthesis is catalyzed by the lpxc enzyme. in escherichia coli, the cellular concentration of lpxc is adjusted by the only essential protease in this organism, the membrane-anchored metalloprotease ftsh. turnover of e. coli lpxc requires a length- and sequence-specific c-terminal ... | 2010 | 21193611 |
| syntheses, structures and antibiotic activities of lpxc inhibitors based on the diacetylene scaffold. | compounds inhibiting lpxc in the lipid a biosynthetic pathway are promising leads for novel antibiotics against multidrug-resistant gram-negative pathogens. we report the syntheses and structural and biochemical characterizations of lpxc inhibitors based on a diphenyl-diacetylene (1,4-diphenyl-1,3-butadiyne) threonyl-hydroxamate scaffold. these studies provide a molecular interpretation for the differential antibiotic activities of compounds with a substituted distal phenyl ring as well as the a ... | 2010 | 21194954 |
| syntheses, structures and antibiotic activities of lpxc inhibitors based on the diacetylene scaffold. | compounds inhibiting lpxc in the lipid a biosynthetic pathway are promising leads for novel antibiotics against multidrug-resistant gram-negative pathogens. we report the syntheses and structural and biochemical characterizations of lpxc inhibitors based on a diphenyl-diacetylene (1,4-diphenyl-1,3-butadiyne) threonyl-hydroxamate scaffold. these studies provide a molecular interpretation for the differential antibiotic activities of compounds with a substituted distal phenyl ring as well as the a ... | 2010 | 21194954 |
| hydroxylated ornithine lipids increase stress tolerance in rhizobium tropici ciat899. | ornithine lipids (ols) are widespread among gram-negative bacteria. their basic structure consists of a 3-hydroxy fatty acyl group attached in amide linkage to the α-amino group of ornithine and a second fatty acyl group ester-linked to the 3-hydroxy position of the first fatty acid. ols can be hydroxylated within the secondary fatty acyl moiety and this modification has been related to increased stress tolerance. rhizobium tropici, a nodule-forming α-proteobacterium known for its stress toleran ... | 2011 | 21205018 |
| the transport mechanism of bacterial cu+-atpases: distinct efflux rates adapted to different function. | cu(+)-atpases play a key role in bacterial cu(+) homeostasis by participating in cu(+) detoxification and cuproprotein assembly. characterization of archaeoglobus fulgidus copa, a model protein within the subfamily of p(1b-1) type atpases, has provided structural and mechanistic details on this group of transporters. atomic resolution structures of cytoplasmic regulatory metal binding domains (mbds) and catalytic actuator, phosphorylation, and nucleotide binding domains are available. these, in ... | 2011 | 21210186 |
| cyclic gmp controls rhodospirillum centenum cyst development. | adenylyl cyclases are widely distributed across all kingdoms whereas guanylyl cyclases are generally thought to be restricted to eukaryotes. here we report that the α-proteobacterium rhodospirillum centenum secretes cgmp when developing cysts and that a guanylyl cyclase deletion strain fails to synthesize cgmp and is defective in cyst formation. the r. centenum cyclase was purified and shown to effectively synthesize cgmp from gtp in vitro, demonstrating that it is a functional guanylyl cyclase. ... | 2011 | 21214648 |
| solution structure of 4'-phosphopantetheine - gmacp3 from geobacter metallireducens: a specialized acyl carrier protein with atypical structural features and a putative role in lipopolysaccharide biosynthesis. | gmacp3 from geobacter metallireducens is a specialized acyl carrier protein (acp) whose gene, gmet_2339, is located near genes encoding many proteins involved in lipopolysaccharide (lps) biosynthesis, indicating a likely function for gmacp3 in lps production. by overexpression in escherichia coli, about 50% holo-gmacp3 and 50% apo-gmacp3 were obtained. apo-gmacp3 exhibited slow precipitation and non-monomeric behavior by (15)n nmr relaxation measurements. addition of 4'-phosphopantetheine (4'-pp ... | 2011 | 21235239 |
| a processive glycosyltransferase involved in glycolipid synthesis during phosphate deprivation in mesorhizobium loti. | natural habitats are often characterized by a low availability of phosphate. in plants and many bacteria, phosphate deficiency causes different physiological responses, including the replacement of phosphoglycerolipids in the membranes with nonphosphorous lipids. we describe here a processive glycosyltransferase (pgt) in mesorhizobium loti (rhizobiales) involved in the synthesis of di- and triglycosyldiacylglycerols (dglycd and tglycd) during phosphate deprivation. cells of the corresponding δpg ... | 2011 | 21239587 |
| failure to fix nitrogen by non-reproductive symbiotic rhizobia triggers host sanctions that reduce fitness of their reproductive clonemates. | the legume-rhizobia symbiosis is a classical mutualism where fixed carbon and nitrogen are exchanged between the species. nonetheless, the plant carbon that fuels nitrogen (n(2)) fixation could be diverted to rhizobial reproduction by 'cheaters'--rhizobial strains that fix less n(2) but potentially gain the benefit of fixation by other rhizobia. host sanctions can decrease the relative fitness of less-beneficial reproductive bacteroids and prevent cheaters from breaking down the mutualism. howev ... | 2011 | 21270038 |
| genome sequence analyses of pseudomonas savastanoi pv. glycinea and subtractive hybridization-based comparative genomics with nine pseudomonads. | bacterial blight, caused by pseudomonas savastanoi pv. glycinea (psg), is a common disease of soybean. in an effort to compare a current field isolate with one isolated in the early 1960s, the genomes of two psg strains, race 4 and b076, were sequenced using 454 pyrosequencing. the genomes of both psg strains share more than 4,900 highly conserved genes, indicating very low genetic diversity between psg genomes. though conserved, genome rearrangements and recombination events occur commonly with ... | 2011 | 21304594 |
| complete genome sequence of rhizobium leguminosarum bv trifolii strain wsm2304, an effective microsymbiont of the south american clover trifolium polymorphum. | rhizobium leguminosarum bv trifolii is the effective nitrogen fixing microsymbiont of a diverse range of annual and perennial trifolium (clover) species. strain wsm2304 is an aerobic, motile, non-spore forming, gram-negative rod, isolated from trifolium polymorphum in uruguay in 1998. this microsymbiont predominated in the perennial grasslands of glencoe research station, in uruguay, to competitively nodulate its host, and fix atmospheric nitrogen. here we describe the basic features of wsm2304, ... | 2010 | 21304679 |
| complete genome sequence of rhizobium leguminosarum bv. trifolii strain wsm1325, an effective microsymbiont of annual mediterranean clovers. | rhizobium leguminosarum bv trifolii is a soil-inhabiting bacterium that has the capacity to be an effective nitrogen fixing microsymbiont of a diverse range of annual trifolium (clover) species. strain wsm1325 is an aerobic, motile, non-spore forming, gram-negative rod isolated from root nodules collected in 1993 from the greek island of serifos. wsm1325 is produced commercially in australia as an inoculant for a broad range of annual clovers of mediterranean origin due to its superior attribute ... | 2010 | 21304718 |
| high-throughput screening of microbial adaptation to environmental stress. | we developed a microwell plate, high-throughput, screening method aimed at quantitating the tolerance of a panel of gram-positive and gram-negative bacteria to metals (frankia sp., escherichia coli, cupriavidus metallidurans, rhizobium leguminosarum, and streptomyces scabies). microbial viability was quantified using mts; a tetrazolium salt converted to a water-soluble formazan through microbial reduction. in this paper, we present the stepwise development of the method, highlighting the main el ... | 2011 | 21315114 |
| type vi secretion system in pseudomonas aeruginosa: secretion and multimerization of vgrg proteins. | pseudomonas aeruginosa is a gram-negative bacterium causing chronic infections in cystic fibrosis patients. such infections are associated with an active type vi secretion system (t6ss), which consists of about 15 conserved components, including the aaa+ atpase, clpv. the t6ss secretes two categories of proteins, vgrg and hcp. hcp is structurally similar to a phage tail tube component, whereas vgrg proteins show similarity to the puncturing device at the tip of the phage tube. in p. aeruginosa, ... | 2011 | 21325275 |
| identification and assessment of symbiotic effectiveness of phage-typed rhizobium leguminosarum strains on lentil (lens culinaris medik) cultivars. | symbiotic effectiveness of 19 indigenous and two exotic (usda 2426 and usda 2431) strains of lentil rhizobium belonging to different phage-sensitive and phage-resistant groups was compared under axenic condition. four strains (usda 2431, bhulr 104, bhulr 113, and bhulr 115) sensitive to different phages were found significantly superior over others in terms of nodule number, acetylene reduction activity, and total dry weight per plant. inoculation response of these strains was then evaluated on ... | 2011 | 21327559 |
| organic hydroperoxide resistance protein and ergothioneine compensate for loss of mycothiol in mycobacterium smegmatis mutants. | the msha::tn5 mutant of mycobacterium smegmatis does not produce mycothiol (msh) and was found to markedly overproduce both ergothioneine and an ~15-kda protein determined to be organic hydroperoxide resistance protein (ohr). an msha(g32d) mutant lacking msh overproduced ergothioneine but not ohr. comparison of the mutant phenotypes with those of the wild-type strain indicated the following: ohr protects against organic hydroperoxide toxicity, whereas ergothioneine does not; an additional msh-de ... | 2011 | 21335456 |
| multi-factorial engineering of heterologous polyketide production in escherichia coli reveals complex pathway interactions. | polyketides represent a significant fraction of all natural products. many possess pharmacological activity which makes them attractive drug candidates. the production of the parent macrocyclic aglycones is catalyzed by multi-modular polyketide synthases utilizing short-chain acyl-coa monomers. when producing polyketides through heterologous hosts, one must not only functionally express the synthase itself, but activate the machinery used to generate the required substrate acyl-coa's. as a resul ... | 2011 | 21337322 |
| deletion of the signalling molecule synthase scba has pleiotropic effects on secondary metabolite biosynthesis, morphological differentiation and primary metabolism in streptomyces coelicolor a3(2). | streptomycetes have high biotechnological relevance as producers of diverse metabolites widely used in medical and agricultural applications. the biosynthesis of these metabolites is controlled by signalling molecules, γ-butyrolactones, that act as bacterial hormones. in streptomyces coelicolor, a group of signalling molecules called scbs (s. coelicolorbutanolides) regulates production of the pigmented antibiotics coelicolor polyketide (cpk), actinorhodin and undecylprodigiosin. the γ-butyrolact ... | 2010 | 21342469 |
| mutation of a broadly conserved operon (rl3499-rl3502) from rhizobium leguminosarum biovar viciae causes defects in cell morphology and envelope integrity. | the bacterial cell envelope is of critical importance to the function and survival of the cell; it acts as a barrier against harmful toxins while allowing the flow of nutrients into the cell. it also serves as a point of physical contact between a bacterial cell and its host. hence, the cell envelope of rhizobium leguminosarum is critical to cell survival under both free-living and symbiotic conditions. transposon mutagenesis of r. leguminosarum strain 3841 followed by a screen to isolate mutant ... | 2011 | 21357485 |
| role of baca in lipopolysaccharide synthesis, peptide transport, and nodulation by rhizobium sp. strain ngr234. | baca of sinorhizobium meliloti plays an essential role in the establishment of nitrogen-fixing symbioses with medicago plants, where it is involved in peptide import and in the addition of very-long-chain fatty acids (vlcfa) to lipid a of lipopolysaccharide (lps). we investigated the role of baca in rhizobium species strain ngr234 by mutating the baca gene. in the ngr234 baca mutant, peptide import was impaired, but no effect on vlcfa addition was observed. more importantly, the symbiotic abilit ... | 2011 | 21357487 |
| regulation of type vi secretion gene clusters by sigma54 and cognate enhancer binding proteins. | type vi secretion systems (t6ss) are bacteriophage-derived macromolecular machines responsible for the release of at least two proteins in the milieu, which are thought to form an extracellular appendage. although several t6ss have been shown to be involved in the virulence of animal and plant pathogens, clusters encoding these machines are found in the genomes of most species of gram-negative bacteria, including soil, marine, and environmental isolates. t6ss have been associated with several ph ... | 2011 | 21378190 |
| characterization of n-acylhomoserine lactone-degrading bacteria associated with the zingiber officinale (ginger) rhizosphere: co-existence of quorum quenching and quorum sensing in acinetobacter and burkholderia. | cell-to-cell communication (quorum sensing (qs)) co-ordinates bacterial behaviour at a population level. consequently the behaviour of a natural multi-species community is likely to depend at least in part on co-existing qs and quorum quenching (qq) activities. here we sought to discover novel n-acylhomoserine lactone (ahl)-dependent qs and qq strains by investigating a bacterial community associated with the rhizosphere of ginger (zingiber officinale) growing in the malaysian rainforest. | 2011 | 21385437 |
| determination of the electrokinetic potential of rhizobium leguminosarum bv trifolii rt24.2 using laser doppler velocimetry--a methodological study. | electrokinetic potential (+â, zeta potential) is one of the parameters which characterize the physicochemical properties of the bacterial cell envelope. the term is often used in the context of adhesiveness of bacteria and biofilm formation. this work presents the methodological aspects of zeta potential determination in strain rt24.2 of rhizobium leguminosarum using laser doppler velocimetry combined with phase analysis light scattering and changed electric field techniques. the influence of me ... | 2011 | 21397639 |
| multilocus sequence-based analysis delineates a clonal population of agrobacterium (rhizobium) radiobacter (agrobacterium tumefaciens) of human origin. | the genus agrobacterium includes plant-associated bacteria and opportunistic human pathogens. taxonomy and nomenclature within the genus remain controversial. in particular, isolates of human origin were all affiliated with the species agrobacterium (rhizobium) radiobacter, while phytopathogenic strains were designated under the synonym denomination agrobacterium tumefaciens. in order to study the relative distribution of agrobacterium strains according to their origins, we performed a multilocu ... | 2011 | 21398532 |
| development of functional symbiotic white clover root hairs and nodules requires tightly regulated production of rhizobial cellulase celc2. | the establishment of rhizobia as nitrogen-fixing endosymbionts within legume root nodules requires the disruption of the plant cell wall to breach the host barrier at strategic infection sites in the root hair tip and at points of bacterial release from infection threads (it) within the root cortex. we previously found that rhizobium leguminosarum bv. trifolii uses its chromosomally encoded celc2 cellulase to erode the noncrystalline wall at the apex of root hairs, thereby creating the primary p ... | 2011 | 21405987 |
| the maturation factors hoxr and hoxt contribute to oxygen tolerance of membrane-bound [nife] hydrogenase in ralstonia eutropha h16. | the membrane-bound [nife] hydrogenase (mbh) of ralstonia eutropha h16 undergoes a complex maturation process comprising cofactor assembly and incorporation, subunit oligomerization, and finally twin-arginine-dependent membrane translocation. due to its outstanding o(2) and co tolerance, the mbh is of biotechnological interest and serves as a molecular model for a robust hydrogen catalyst. adaptation of the enzyme to oxygen exposure has to take into account not only the catalytic reaction but als ... | 2011 | 21441514 |
| biochemical characterization of sinorhizobium meliloti mutants reveals gene products involved in the biosynthesis of the unusual lipid a very long-chain fatty acid. | sinorhizobium meliloti forms a symbiosis with the legume alfalfa, whereby it differentiates into a nitrogen-fixing bacteroid. the lipid a species of s. meliloti are modified with very long-chain fatty acids (vlcfas), which play a central role in bacteroid development. a six-gene cluster was hypothesized to be essential for the biosynthesis of vlcfa-modified lipid a. previously, two cluster gene products, acpxl and lpxxl, were found to be essential for s. meliloti lipid a vlcfa biosynthesis. in t ... | 2011 | 21454518 |
| housekeeping genes essential for pantothenate biosynthesis are plasmid-encoded in rhizobium etli and rhizobium leguminosarum. | a traditional concept in bacterial genetics states that housekeeping genes, those involved in basic metabolic functions needed for maintenance of the cell, are encoded in the chromosome, whereas genes required for dealing with challenging environmental conditions are located in plasmids. exceptions to this rule have emerged from genomic sequence data of bacteria with multipartite genomes. the genome sequence of r. etli cfn42 predicts the presence of panc and panb genes clustered together on the ... | 2011 | 21463532 |
| heme binding to the second, lower-affinity site of the global iron regulator irr from rhizobium leguminosarum promotes oligomerization. | the iron responsive regulator irr is found in a wide range of α-proteobacteria, where it regulates many genes in response to the essential but toxic metal iron. unlike fur, the transcriptional regulator that is used for iron homeostasis by almost all other bacterial lineages, irr does not sense fe(2+) directly, but, rather, interacts with a physiologically important form of iron, namely heme. recent studies of irr from the n(2) -fixing symbiont rhizobium leguminosarum (irr(rl) ) showed that it b ... | 2011 | 21481185 |
| xerr, a negative regulator of xccr in xanthomonas campestris pv. campestris, relieves its repressor function in planta. | we previously reported that xccr, a luxr-type regulator of xanthomonas campestris pv. campestris (xcc), activates the downstream proline iminopeptidase virulence gene (pip) in response to certain host plant factor(s). in this report, we further show that the expression of the xccr gene was repressed in the culture medium by an ntrc-type response regulator, which we named xerr (xccr expression-related, repressor), and that this repression was relieved when the bacteria were grown in planta. such ... | 2011 | 21483448 |
| a chaperonin subunit with unique structures is essential for folding of a specific substrate. | type i chaperonins are large, double-ring complexes present in bacteria (groel), mitochondria (hsp60), and chloroplasts (cpn60), which are involved in mediating the folding of newly synthesized, translocated, or stress-denatured proteins. in escherichia coli, groel comprises 14 identical subunits and has been exquisitely optimized to fold its broad range of substrates. however, multiple cpn60 subunits with different expression profiles have evolved in chloroplasts. here, we show that, in arabido ... | 2011 | 21483722 |
| molecular diversity and phylogeny of rhizobia associated with lablab purpureus (linn.) grown in southern china. | as an introduced plant, lablab purpureus serves as a vegetable, herbal medicine, forage and green manure in china. in order to investigate the diversity of rhizobia associated with this plant, a total of 49 rhizobial strains isolated from ten provinces of southern china were analyzed in the present study with restriction fragment length polymorphism and/or sequence analyses of housekeeping genes (16s rrna, igs, atpd, glnii and reca) and symbiotic genes (nifh and nodc). the results defined the l. ... | 2011 | 21498018 |
| bioinformatic characterization of the trimeric intracellular cation-specific channel protein family. | trimeric intracellular cation-specific (tric) channels are integral to muscle excitation-contraction coupling. tric channels provide counter-ionic flux when calcium is rapidly transported from intracellular stores to the cell cytoplasm. until recently, knowledge of the presence of these proteins was limited to animals. we analyzed the tric family and identified a profusion of prokaryotic family members with topologies and motifs similar to those of their eukaryotic counterparts. prokaryotic memb ... | 2011 | 21519847 |
| a bacterial sub-family of luxr regulators that respond to plant compounds. | pseudomonas fluorescens are rhizobacteria known for their biocontrol properties; several antimicrobial functions are crucial for this process; experiments here investigate the modulation of their expression during the plant-bacterial interaction. the role of a luxr family regulator in interkingdom signalling has been investigated using genome-scale transcriptome analysis, gene promoter studies in vivo and in vitro, biocontrol assays and response to plant compounds. psor, a luxr solo or orphan re ... | 2011 | 21531826 |
| impact of organic fertilizers with and without chemical fertilizers on soil chemical properties and the establishment of nitrogen-fixing bacteria in the rhizosphere. | effects of organic fertilizers with and without the application of chemical fertilizers for seven years as part of a wheat-pearl millet cropping sequence on soil chemical properties and the establishment of nitrogen fixing bacteria in the rhizosphere were examined. the application of farmyard manure, poultry manure, and sugarcane filter cake alone or in combination with chemical fertilizers improved the soil organic c, total n, p, and k status. larger populations of azotobacter chroococcum and r ... | 2008 | 21558724 |
| population genomics of sinorhizobium medicae based on low-coverage sequencing of sympatric isolates. | we investigated the genomic diversity of a local population of the symbiotic bacterium sinorhizobium medicae, isolated from the roots of wild medicago lupulina plants, in order to assess genomic diversity, to identify genomic regions influenced by duplication, deletion or strong selection, and to explore the composition of the pan-genome. partial genome sequences of 12 isolates were obtained by roche 454 shotgun sequencing (average 5.3 mb per isolate) and compared with the published sequence of ... | 2011 | 21562597 |
| azorhirobial chromosome partition gene (para) is involved in the onset of bacteroid differentiation in sesbania rostrata stem-nodule development. | a para gene in-frame deletion mutant of azorhizobium caulinodans ors571 (ors571-δpara) was constructed to evaluate the roles of the chromosome partitioning gene on various bacterial traits and on the development of stem-positioned nodules. the δpara mutant showed a pleiomorphic cell shape phenotype, and was polyploidy with differences in nucleoid sizes due to dramatic defects in chromosome partitioning. upon inoculating the δpara mutant onto the stem of sesbania rostrata, three types of immature ... | 2011 | 21571889 |
| anti-parallel and interlinked control of cellular iron levels by the irr and rira regulators of agrobacterium tumefaciens. | the plant pathogen agrobacterium tumefaciens encodes predicted iron-responsive regulators, irr and rira, that function in several other bacteria to control the response to environmental iron levels. deletion mutations of irr and rira, alone and in combination, were evaluated for their impact on cellular iron response. growth was severely diminished in the δirr mutant under iron limiting conditions, but reversed to wild type levels in an δirrδrira mutant. the level of uncomplexed iron in the δirr ... | 2011 | 21602352 |
| development of real-time pcr assay for detection and quantification of rhizobium leguminosarum and discrimination between different biovars in soil contaminated with zinc. | primers were designed to target 16s rrna and nodd genes of rhizobium leguminosarum from dna extracted from two different soil types contaminated with zn applied in sewage sludge. numbers of rhizobia estimated using 16s rrna gene copy number were in higher abundance than those estimated by both nodd and the most probable number (mpn) enumeration method using a plant trap host. both 16s rrna gene copies and the mpn rhizobia declined with increased levels of zn contamination as did the abundance of ... | 2011 | 21602380 |