| [biochemical and physiological features of sinorhizobium meliloti and sorghum bicolor interaction in the presence of phenanthrene]. | | 2009 | 19580158 |
| characterization of the dicarboxylate transporter dcta in corynebacterium glutamicum. | transporters of the dicarboxylate amino acid-cation symporter family often mediate uptake of c(4)-dicarboxylates, such as succinate or l-malate, in bacteria. a member of this family, dicarboxylate transporter a (dcta) from corynebacterium glutamicum, was characterized to catalyze uptake of the c(4)-dicarboxylates succinate, fumarate, and l-malate, which was inhibited by oxaloacetate, 2-oxoglutarate, and glyoxylate. dcta activity was not affected by sodium availability but was dependent on the el ... | 2009 | 19581365 |
| (homo)glutathione depletion modulates host gene expression during the symbiotic interaction between medicago truncatula and sinorhizobium meliloti. | under nitrogen-limiting conditions, legumes interact with symbiotic rhizobia to produce nitrogen-fixing root nodules. we have previously shown that glutathione and homoglutathione [(h)gsh] deficiencies impaired medicago truncatula symbiosis efficiency, showing the importance of the low m(r) thiols during the nodulation process in the model legume m. truncatula. in this study, the plant transcriptomic response to sinorhizobium meliloti infection under (h)gsh depletion was investigated using cdna- ... | 2009 | 19587096 |
| detection of genomic islands via segmental genome heterogeneity. | while the recognition of genomic islands can be a powerful mechanism for identifying genes that distinguish related bacteria, few methods have been developed to identify them specifically. rather, identification of islands often begins with cataloging individual genes likely to have been recently introduced into the genome; regions with many putative alien genes are then examined for other features suggestive of recent acquisition of a large genomic region. when few phylogenetic relatives are av ... | 2009 | 19589805 |
| word-based characterization of promoters involved in human dna repair pathways. | dna repair genes provide an important contribution towards the surveillance and repair of dna damage. these genes produce a large network of interacting proteins whose mrna expression is likely to be regulated by similar regulatory factors. full characterization of promoters of dna repair genes and the similarities among them will more fully elucidate the regulatory networks that activate or inhibit their expression. to address this goal, the authors introduce a technique to find regulatory geno ... | 2009 | 19594877 |
| legumes regulate rhizobium bacteroid development and persistence by the supply of branched-chain amino acids. | one of the largest contributions to biologically available nitrogen comes from the reduction of n(2) to ammonia by rhizobia in symbiosis with legumes. plants supply dicarboxylic acids as a carbon source to bacteroids, and in return they receive ammonia. however, metabolic exchange must be more complex, because effective n(2) fixation by rhizobium leguminosarum bv viciae bacteroids requires either one of two broad-specificity amino acid abc transporters (aap and bra). it was proposed that amino a ... | 2009 | 19597156 |
| sinorhizobium meliloti cpdr1 is critical for co-ordinating cell cycle progression and the symbiotic chronic infection. | atp-driven proteolysis plays a major role in regulating the bacterial cell cycle, development and stress responses. in the nitro -fixing symbiosis with host plants, sinorhizobium meliloti undergoes a profound cellular differentiation, including endoreduplication of the ome. the regulatory mechanisms governing the alterations of the s. meliloti cell cycle in planta are largely unknown. here, we report the characterization of two cpdr homologues, cpdr1 and cpdr2, of s. meliloti that encode single- ... | 2009 | 19602145 |
| cellular localization of predicted transmembrane and soluble chemoreceptors in sinorhizobium meliloti. | bacterial chemoreceptors primarily locate in clusters at the cell pole, where they form large sensory complexes which recruit cytoplasmic components of the signaling pathway. the genome of the soil bacterium sinorhizobium meliloti encodes seven transmembrane and two soluble chemoreceptors. we have investigated the localization of all nine chemoreceptors in vivo using genome-encoded fusions to a variant of the enhanced green fluorescent protein and to monomeric red fluorescent protein. six of the ... | 2009 | 19617359 |
| stimulation of the maltose transporter atpase by unliganded maltose binding protein. | atp hydrolysis by the maltose transporter (malfgk(2)) is regulated by maltose binding protein (mbp). binding of maltose to mbp brings about a conformational change from open to closed that leads to a strong stimulation of the malfgk(2) atpase. in this study, we address the long-standing but enigmatic observation that unliganded mbp is also able to stimulate malfgk(2). although the mechanism of this stimulation is not understood, it is sometimes attributed to a small amount of closed (but unligan ... | 2009 | 19630440 |
| sulfite oxidation in sinorhizobium meliloti. | sulfite-oxidizing enzymes (soes) are crucial for the metabolism of many cells and are particularly important in bacteria oxidizing inorganic or organic sulfur compounds. however, little is known about soe diversity and metabolic roles. sinorhizobium meliloti contains four candidate genes encoding soes of three different types, and in this work we have investigated the role of soes in s. meliloti and their possible link to the metabolism of the organosulfonate taurine. low level soe activity (app ... | 2009 | 19632192 |
| the novel genes emmabc are associated with exopolysaccharide production, motility, stress adaptation, and symbiosis in sinorhizobium meliloti. | the nitrogen-fixing symbiont sinorhizobium meliloti senses and responds to constantly changing environmental conditions as it makes its way through the soil in search of its leguminous plant host, medicago sativa (alfalfa). as a result, this bacterium regulates various aspects of its physiology in order to respond appropriately to stress, starvation, and competition. for example, exopolysaccharide production, which has been shown to play an important role in the ability of s. meliloti to success ... | 2009 | 19633078 |
| structural analysis of the choline-binding protein chox in a semi-closed and ligand-free conformation. | the periplasmic ligand-binding protein chox is part of the abc transport system chovwx that imports choline as a nutrient into the soil bacterium sinorhizobium meliloti. we have recently reported the crystal structures of chox in complex with its ligands choline and acetylcholine and the structure of a fully closed but substrate-free state of chox. this latter structure revealed an architecture of the ligand-binding site that is superimposable to the closed, ligand-bound form of chox. we report ... | 2009 | 19642870 |
| matching biochemical reaction kinetics to the timescales of life: structural determinants that influence the autodephosphorylation rate of response regulator proteins. | in two-component regulatory systems, covalent phosphorylation typically activates the response regulator signaling protein, and hydrolysis of the phosphoryl group reestablishes the inactive state. despite highly conserved three-dimensional structures and active-site features, the rates of catalytic autodephosphorylation for different response regulators vary by a factor of almost 10(6). previous studies identified two variable active-site residues, corresponding to escherichia coli chey residues ... | 2009 | 19646451 |
| homotaurine metabolized to 3-sulfopropanoate in cupriavidus necator h16: enzymes and genes in a patchwork pathway. | homotaurine (3-aminopropanesulfonate), a natural product and an analogue of gaba (4-aminobutyrate), was found to be a sole source of nitrogen for cupriavidus necator (ralstonia eutropha) h16, whose genome sequence is known. homotaurine nitrogen was assimilated into cell material, and the quantitative fate of the organosulfonate was sulfopropanoate, which was recovered in the growth medium. the first scalar reaction was shown to be inducible homotaurine:2-oxoglutarate aminotransferase, which rele ... | 2009 | 19648235 |
| homologues of the bacillus subtilis spovb protein are involved in cell wall metabolism. | members of the cog2244 protein family are integral membrane proteins involved in synthesis of a variety of extracellular polymers. in several cases, these proteins have been suggested to move lipid-linked oligomers across the membrane or, in the case of escherichia coli mvin, to flip the lipid ii peptidoglycan precursor. bacillus subtilis spovb was the first member of this family implicated in peptidoglycan synthesis and is required for spore cortex polymerization. three other cog2244 members wi ... | 2009 | 19648239 |
| mrdh, a novel metal resistance determinant of pseudomonas putida kt2440, is flanked by metal-inducible mobile genetic elements. | we report here the identification and characterization of mrdh, a novel chromosomal metal resistance determinant, located in the genomic island 55 of pseudomonas putida kt2440. it encodes for mrdh, a predicted protein of approximately 40 kda with a chimeric domain organization derived from the rcna and rnd (for resistance-nodulation-cell division) metal efflux proteins. the metal resistance function of mrdh was identified by the ability to confer nickel resistance upon its complementation into r ... | 2009 | 19648243 |
| the structure of a putative s-formylglutathione hydrolase from agrobacterium tumefaciens. | the structure of the atu1476 protein from agrobacterium tumefaciens was determined at 2 a resolution. the crystal structure and biochemical characterization of this enzyme support the conclusion that this protein is an s-formylglutathione hydrolase (atusfgh). the three-dimensional structure of atusfgh contains the alpha/beta hydrolase fold topology and exists as a homo-dimer. contacts between the two monomers in the dimer are formed both by hydrogen bonds and salt bridges. biochemical characteri ... | 2009 | 19653299 |
| identification of a hydroxyproline transport system in the legume endosymbiont sinorhizobium meliloti. | hydroxyproline-rich proteins in plants offer a source of carbon and nitrogen to soil-dwelling microorganisms in the form of root exudates and decaying organic matter. this report describes an abc-type transport system dedicated to the uptake of hydroxyproline in the legume endosymbiont sinorhizobium meliloti. we have designated genes involved in hydroxyproline metabolism as hyp genes and show that an s. meliloti strain lacking putative transport genes (deltahypmnpq) is unable to grow with or tra ... | 2009 | 19656046 |
| gene expression profiling in susceptible interaction of grapevine with its fungal pathogen eutypa lata: extending mapman ontology for grapevine. | whole genome transcriptomics analysis is a very powerful approach because it gives an overview of the activity of genes in certain cells or tissue types. however, biological interpretation of such results can be rather tedious. mapman is a software tool that displays large datasets (e.g. gene expression data) onto diagrams of metabolic pathways or other processes and thus enables easier interpretation of results. the grapevine (vitis vinifera) genome sequence has recently become available bringi ... | 2009 | 19656401 |
| symbiotic diversity of ensifer meliloti strains recovered from various legume species in tunisia. | ensifer meliloti (formerly sinorhizobium meliloti) was first considered as a specific microsymbiont of medicago, melilotus and trigonella. however, strains of e. meliloti were recovered from root nodules of various legume species and their symbiotic status still remains unclear. here, we further investigate the specificity of these strains. a collection of 47 e. meliloti strains isolated in tunisia from root nodules of medicago truncatula, medicago sativa, medicago ciliaris, medicago laciniata, ... | 2009 | 19665858 |
| bacillus subtilis homologs of mvin (murj), the putative escherichia coli lipid ii flippase, are not essential for growth. | although peptidoglycan synthesis is one of the best-studied metabolic pathways in bacteria, the mechanism underlying the membrane translocation of lipid ii, the undecaprenyl-disaccharide pentapeptide peptidoglycan precursor, remains mysterious. recently, it was proposed that the essential escherichia coli mvin gene encodes the lipid ii flippase. bacillus subtilis contains four proteins that are putatively homologous to mvin, including spovb, previously reported to be necessary for spore cortex p ... | 2009 | 19666716 |
| surface colonization by marine roseobacters: integrating genotype and phenotype. | the roseobacter clade is a broadly distributed, abundant, and biogeochemically relevant group of marine bacteria. representatives are often associated with organic surfaces in disparate marine environments, suggesting that a sessile lifestyle is central to the ecology of lineage members. the importance of surface association and colonization has been demonstrated recently for select strains, and it has been hypothesized that production of antimicrobial agents, cell density-dependent regulatory m ... | 2009 | 19666726 |
| a genome-wide compilation of the two-component systems in lotus japonicus. | the two-component systems (tcs), or histidine-to-aspartate phosphorelays, are evolutionarily conserved common signal transduction mechanisms that are implicated in a wide variety of cellular responses to environmental stimuli in both prokaryotes and eukaryotes including plants. among higher plants, legumes including lotus japonicus have a unique ability to engage in beneficial symbiosis with nitrogen-fixing bacteria. we previously presented a genome-wide compiled list of tcs-associated component ... | 2009 | 19675111 |
| cell-free escherichia coli-based system to screen for quorum-sensing molecules interacting with quorum receptor proteins of streptomyces coelicolor. | quorum sensing (qs) is mediated by small molecules and involved in diverse cellular functions, such as virulence, biofilm formation, secondary metabolism, and cell differentiation. in this study, we developed a rapid and effective screening tool based on a cell-free escherichia coli-based expression system to identify qs molecules of streptomyces. the binding of qs molecules to gamma-butyrolactone receptor scbr was monitored by changes in the expression levels of the green fluorescent protein re ... | 2009 | 19684180 |
| the role of the conserved phenylalanine in the sigma54-interacting gaftga motif of bacterial enhancer binding proteins. | sigma(54)-dependent transcription requires activation by bacterial enhancer binding proteins (bebps). bebps are members of the aaa+ (atpases associated with various cellular activities) protein family and typically form hexameric structures that are crucial for their atpase activity. the precise mechanism by which the energy derived from atp hydrolysis is coupled to biological output has several unknowns. here we use escherichia coli pspf, a model bebp involved in the transcription of stress res ... | 2009 | 19692583 |
| acc (1-aminocyclopropane-1-carboxylate) deaminase activity, a widespread trait in burkholderia species, and its growth-promoting effect on tomato plants. | the genus burkholderia includes pathogens of plants and animals and some human opportunistic pathogens, such as the burkholderia cepacia complex (bcc), but most species are nonpathogenic, plant associated, and rhizospheric or endophytic. since rhizobacteria expressing acc (1-aminocyclopropane-1-carboxylate) deaminase may enhance plant growth by lowering plant ethylene levels, in this work we investigated the presence of acc deaminase activity and the acds gene in 45 strains, most of which are pl ... | 2009 | 19700546 |
| a nuclear-targeted cameleon demonstrates intranuclear ca2+ spiking in medicago truncatula root hairs in response to rhizobial nodulation factors. | lipochitooligosaccharide nodulation factors (nfs) secreted by endosymbiotic nitrogen-fixing rhizobia trigger ca(2+) spiking in the cytoplasmic perinuclear region of host legume root hairs. to determine whether nfs also elicit ca(2+) responses within the plant cell nucleus we have made use of a nucleoplasmin-tagged cameleon (nupyc2.1). confocal microscopy using this nuclear-specific calcium reporter has revealed sustained and regular ca(2+) spiking within the nuclear compartment of medicago trunc ... | 2009 | 19700563 |
| can differences of nitrogen nutrition level among medicago truncatula genotypes be assessed non-destructively?: probing with a recombinant inbred lines population. | the international consensus on medicago truncatula as a model system has lead to the development of powerful approaches for dissecting the genetic and molecular bases of legume nitrogen nutrition. however, such approaches now come up against a poor knowledge of the phenotypic traits that should be used for the large-scale screening of the genotypic variability associated with nitrogen nutrition. this issue was unravelled in a previous report, in which an ecophysiological approach allowed a bette ... | 2009 | 19704700 |
| convergent evolution of metabolic roles in bacterial co-symbionts of insects. | a strictly host-dependent lifestyle has profound evolutionary consequences for bacterial genomes. most prominent is a sometimes-dramatic amount of gene loss and genome reduction. recently, highly reduced genomes from the co-resident intracellular symbionts of sharpshooters were shown to exhibit a striking level of metabolic interdependence. one symbiont, called sulcia muelleri (bacteroidetes), can produce eight of the 10 essential amino acids, despite having a genome of only 245 kb. the other, b ... | 2009 | 19706397 |
| study of free oligosaccharides derived from the bacterial n-glycosylation pathway. | the food-borne pathogen campylobacter jejuni is one of the leading causes of bacterial gastroenteritis worldwide and the most frequent antecedent in neuropathies such as the guillain-barré and miller fisher syndromes. c. jejuni was demonstrated to possess an n-linked protein glycosylation pathway that adds a conserved heptasaccharide to >40 periplasmic and membrane proteins. recently, we showed that c. jejuni also produces free heptasaccharides derived from the n-glycan pathway reminiscent of th ... | 2009 | 19706478 |
| different species and symbiotic genotypes of field rhizobia can nodulate phaseolus vulgaris in tunisian soils. | abstract a collection of 160 isolates of rhizobia nodulating phaseolus vulgaris in three geographical regions in tunisia was characterized by restriction fragment length polymorphism analysis of polymerase chain reaction (pcr)-amplified 16s rdna, nifh and nodc genes. nine groups of rhizobia were delineated: rhizobium gallicum biovar (bv.) gallicum, rhizobium leguminosarum bv. phaseoli and bv. viciae, rhizobium etli bv. phaseoli, rhizobium giardinii bv. giardinii, and four groups related to speci ... | 2002 | 19709241 |
| attachment to plant roots and nod gene expression are not affected by ph or calcium in the acid-tolerant alfalfa-nodulating bacteria rhizobium sp. lpu83. | soil acidification is one of the environmental factors that more strongly hampers the establishment of an effective symbiotic interaction between rhizobia and leguminous plants. sinorhizobium meliloti and the acid-tolerant rhizobium sp. strain lpu83 are able to nodulate alfalfa plants at ph 5.6 but both exhibit a delayed nodulation and a reduction in the number of elicited nodules. we show here that the addition of calcium (ca) has no positive effect on the nodulation kinetics shown by lpu83 at ... | 2004 | 19712432 |
| the crystal structure of the escherichia coli autoinducer-2 processing protein lsrf. | many bacteria produce and respond to the quorum sensing signal autoinducer-2 (ai-2). escherichia coli and salmonella typhimurium are among the species with the lsr operon, an operon containing ai-2 transport and processing genes that are up regulated in response to ai-2. one of the lsr proteins, lsrf, has been implicated in processing the phosphorylated form of ai-2. here, we present the structure of lsrf, unliganded and in complex with two phospho-ai-2 analogues, ribose-5-phosphate and ribulose ... | 2009 | 19714241 |
| complete phb mobilization in escherichia coli enhances the stress tolerance: a potential biotechnological application. | abstract: | 2009 | 19719845 |
| n- and c-terminal regions of the quorum-sensing activator trar cooperate in interactions with the alpha and sigma-70 components of rna polymerase. | positive control (pc) mutants defining 20 residues of the quorum-sensing activator trar were isolated that bind dna but show defects in activating transcription from class i, class ii or both types of promoters. these pc residues, located in both the n- and c-terminal regions, combine to form three patches, one on the top (ii) and two near the dna binding domain on both lateral faces of the dimer (i and iii). patches i and ii, but not patch iii, involve residues from both protomers and are essen ... | 2009 | 19732344 |
| the rkp-1 cluster is required for secretion of kdo homopolymeric capsular polysaccharide in sinorhizobium meliloti strain rm1021. | under conditions of nitrogen stress, leguminous plants form symbioses with soil bacteria called rhizobia. this partnership results in the development of structures called root nodules, in which differentiated endosymbiotic bacteria reduce molecular dinitrogen for the host. the establishment of rhizobium-legume symbioses requires the bacterial synthesis of oligosaccharides, exopolysaccharides, and capsular polysaccharides. previous studies suggested that the 3-deoxy-d-manno-oct-2-ulopyranosonic a ... | 2009 | 19734304 |
| mutations that disrupt either the pqq or the gdh gene of rahnella aquatilis abolish the production of an antibacterial substance and result in reduced biological control of grapevine crown gall. | rahnella aquatilis hx2, a biocontrol agent for grapevine crown gall caused by agrobacterium vitis, produces an antibacterial substance that inhibits the growth of a. vitis in vitro. in this study, we show that mh15 and mh16, two tn5-induced mutants of hx2, have lost their abilities to inhibit a. vitis and have reduced biocontrol activities; they grow in logarithmic phase at a rate similar to that of the wild type and have single tn5 insertions. they are also impaired in producing pyrroloquinolin ... | 2009 | 19734331 |
| medicago n2-fixing symbiosomes acquire the endocytic identity marker rab7 but delay the acquisition of vacuolar identity. | rhizobium bacteria form n(2)-fixing organelles, called symbiosomes, inside the cells of legume root nodules. the bacteria are generally thought to enter the cells via an endocytosis-like process. to examine this, we studied the identity of symbiosomes in relation to the endocytic pathway. we show that in medicago truncatula, the small gtpases rab5 and rab7 are endosomal membrane identity markers, marking different (partly overlapping) endosome populations. although symbiosome formation is consid ... | 2009 | 19734435 |
| identification and characterization of new luxr/luxi-type quorum sensing systems from metagenomic libraries. | quorum sensing (qs) cell-cell communication systems are utilized by bacteria to coordinate their behaviour according to cell density. several different types of qs signal molecules have been identified, among which acyl-homoserine lactones (ahls) produced by proteobacteria have been studied to the greatest extent. although qs has been studied extensively in cultured microorganisms, little is known about the qs systems of uncultured microorganisms and the roles of these systems in microbial commu ... | 2010 | 19735279 |
| identification and characterization of new luxr/luxi-type quorum sensing systems from metagenomic libraries. | quorum sensing (qs) cell-cell communication systems are utilized by bacteria to coordinate their behaviour according to cell density. several different types of qs signal molecules have been identified, among which acyl-homoserine lactones (ahls) produced by proteobacteria have been studied to the greatest extent. although qs has been studied extensively in cultured microorganisms, little is known about the qs systems of uncultured microorganisms and the roles of these systems in microbial commu ... | 2010 | 19735279 |
| plant-associated bacterial degradation of toxic organic compounds in soil. | a number of toxic synthetic organic compounds can contaminate environmental soil through either local (e.g., industrial) or diffuse (e.g., agricultural) contamination. increased levels of these toxic organic compounds in the environment have been associated with human health risks including cancer. plant-associated bacteria, such as endophytic bacteria (non-pathogenic bacteria that occur naturally in plants) and rhizospheric bacteria (bacteria that live on and near the roots of plants), have bee ... | 2009 | 19742157 |
| disruption of the bmei0066 gene attenuates the virulence of brucella melitensis and decreases its stress tolerance. | brucella melitensis is a facultative intracellular pathogen. an operon composed of bmei0066, which encodes a two-component response regulator cenr, and bmei0067, which encodes a camp-dependent protein kinase regulatory subunit, has been predicted to exist in many bacterial species. however, little is known about the function of this operon. in order to characterize this operon and assess its role in virulence, we constructed a marked deletion mutant of bmei0066. the mutant was less able to withs ... | 2009 | 19742243 |
| furanose-specific sugar transport: characterization of a bacterial galactofuranose-binding protein. | the widespread utilization of sugars by microbes is reflected in the diversity and multiplicity of cellular transporters used to acquire these compounds from the environment. the model bacterium escherichia coli has numerous transporters that allow it to take up hexoses and pentoses, which recognize the more abundant pyranose forms of these sugars. here we report the biochemical and structural characterization of a transporter protein ytfq from e. coli that forms part of an uncharacterized abc t ... | 2009 | 19744923 |
| identification of functional lsrb-like autoinducer-2 receptors. | although a variety of bacterial species have been reported to use the interspecies communication signal autoinducer-2 (ai-2) to regulate multiple behaviors, the molecular mechanisms of ai-2 recognition and signal transduction remain poorly understood. to date, two types of ai-2 receptors have been identified: luxp, present in vibrio spp., and lsrb, first identified in salmonella enterica serovar typhimurium. in s. typhimurium, lsrb is the ligand binding protein of a transport system that enables ... | 2009 | 19749048 |
| identification of direct transcriptional target genes of exos/chvi two-component signaling in sinorhizobium meliloti. | the sinorhizobium meliloti exos/chvi two-component signaling pathway is required for the development of a nitrogen-fixing symbiosis between s. meliloti and its plant hosts. exos/chvi also has important roles in regulating succinoglycan production, biofilm formation, motility, nutrient utilization, and the viability of free-living bacteria. previous microarray experiments with an exos96::tn5 mutant indicated that exos/chvi influences the expression of a few hundred genes, complicating the investi ... | 2009 | 19749054 |
| a small gtpase of the rab family is required for root hair formation and preinfection stages of the common bean-rhizobium symbiotic association. | legume plants are able to establish a symbiotic relationship with soil bacteria from the genus rhizobium, leading to the formation of nitrogen-fixing root nodules. successful nodulation requires both the formation of infection threads (its) in the root epidermis and the activation of cell division in the cortex to form the nodule primordium. this study describes the characterization of raba2, a common bean (phaseolus vulgaris) cdna previously isolated as differentially expressed in root hairs in ... | 2009 | 19749154 |
| pepsin homologues in bacteria. | peptidase family a1, to which pepsin belongs, had been assumed to be restricted to eukaryotes. the tertiary structure of pepsin shows two lobes with similar folds and it has been suggested that the gene has arisen from an ancient duplication and fusion event. the only sequence similarity between the lobes is restricted to the motif around the active site aspartate and a hydrophobic-hydrophobic-gly motif. together, these contribute to an essential structural feature known as a psi-loop. there is ... | 2009 | 19758436 |
| biochemical and genomic analysis of the denitrification pathway within the genus neisseria. | since neisseria gonorrhoeae and neisseria meningitidis are obligate human pathogens, a comparison with commensal species of the same genus could reveal differences important in pathogenesis. the recent completion of commensal neisseria genome draft assemblies allowed us to perform a comparison of the genes involved in the catalysis, assembly and regulation of the denitrification pathway, which has been implicated in the virulence of several bacteria. all species contained a highly conserved nitr ... | 2009 | 19762442 |
| system-level design of bacterial cell cycle control. | understanding of the cell cycle control logic in caulobacter has progressed to the point where we now have an integrated view of the operation of an entire bacterial cell cycle system functioning as a state machine. oscillating levels of a few temporally-controlled master regulator proteins in a cyclical circuit drive cell cycle progression. to a striking degree, the cell cycle regulation is a whole cell phenomenon. phospho-signaling proteins and proteases dynamically deployed to specific locati ... | 2009 | 19766635 |
| complete genome sequence of the sugarcane nitrogen-fixing endophyte gluconacetobacter diazotrophicus pal5. | gluconacetobacter diazotrophicus pal5 is an endophytic diazotrophic bacterium that lives in association with sugarcane plants. it has important biotechnological features such as nitrogen fixation, plant growth promotion, sugar metabolism pathways, secretion of organic acids, synthesis of auxin and the occurrence of bacteriocins. | 2009 | 19775431 |
| the low-molecular-weight fraction of exopolysaccharide ii from sinorhizobium meliloti is a crucial determinant of biofilm formation. | sinorhizobium meliloti is a soil bacterium that elicits the formation of root organs called nodules on its host plant, medicago sativa. inside these structures, the bacteria are able to convert atmospheric nitrogen into ammonia, which is then used by the plant as a nitrogen source. the synthesis by s. meliloti of at least one exopolysaccharide, succinoglycan or eps ii, is essential for a successful symbiosis. while exopolysaccharide-deficient mutants induce the formation of nodules, they fail to ... | 2009 | 19783627 |
| acyl-homoserine lactones can induce virus production in lysogenic bacteria: an alternative paradigm for prophage induction. | prophage typically are induced to a lytic cycle under stressful environmental conditions or when the host's survival is threatened. however, stress-independent, spontaneous induction also occurs in nature and may be cell density dependent, but the in vivo signal(s) that can trigger induction is unknown. in the present study, we report that acyl-homoserine lactones (ahl), the essential signaling molecules of quorum sensing in many gram-negative bacteria, can trigger phage production in soil and g ... | 2009 | 19783745 |
| gene cloning, protein characterization, and alteration of product selectivity for the trehalulose hydrolase and trehalulose synthase from "pseudomonas mesoacidophila" mx-45. | the naturally occurring structural isomer of sucrose, trehalulose, is produced by sucrose isomerase (si). screening of chromosomal dna from "pseudomonas mesoacidophila" mx-45 with an si-specific probe facilitated the cloning of two adjacent gene homologs, muta and mutb. both genes were expressed separately in escherichia coli, and their enzyme products were characterized. muta hydrolyzed the substrates trehalulose, isomaltulose, and sucrose into glucose and fructose. due to its highest activity ... | 2009 | 19783746 |
| bioinformatics and functional analysis define four distinct groups of alkb dna-dioxygenases in bacteria. | the iron(ii)- and 2-oxoglutarate (2og)-dependent dioxygenase alkb from escherichia coli (ecalkb) repairs alkylation damage in dna by direct reversal. ecalkb substrates include methylated bases, such as 1-methyladenine (m(1)a) and 3-methylcytosine (m(3)c), as well as certain bulkier lesions, for example the exocyclic adduct 1,n(6)-ethenoadenine (epsilona). ecalkb is the only bacterial alkb protein characterized to date, and we here present an extensive bioinformatics and functional analysis of ba ... | 2009 | 19786499 |
| manipulation of auxin transport in plant roots during rhizobium symbiosis and nematode parasitism. | the plant rhizosphere harbors many different microorganisms, ranging from plant growth-promoting bacteria to devastating plant parasites. some of these microbes are able to induce de novo organ formation in infected roots. certain soil bacteria, collectively called rhizobia, form a symbiotic interaction with legumes, leading to the formation of nitrogen-fixing root nodules. sedentary endoparasitic nematodes, on the other hand, induce highly specialized feeding sites in infected plant roots from ... | 2009 | 19789282 |
| transcriptional and post-transcriptional regulation of the gmar antirepressor governs temperature-dependent control of flagellar motility in listeria monocytogenes. | flagellar motility in listeria monocytogenes (lm) is restricted to temperatures below 37 degrees c due to the opposing activities of the mogr transcriptional repressor and the gmar antirepressor. previous studies have suggested that both the degu response regulator and mogr regulate expression of gmar. in this report, we further define the role of degu for gmar production and flagellar motility. we demonstrate that deletion of the receiver domain of degu has no effect on flagellar motility in lm ... | 2009 | 19796338 |
| smc01553 is the sixth acyl carrier protein in sinorhizobium meliloti 1021. | acyl carrier proteins (acps) are required for the transfer of acyl intermediates during fatty acid and polyketide syntheses. in sinorhizobium meliloti 1021 there are five known acps: acpp, nodf, acpxl, the acp domain in rkpa and smb20651. the genome sequence of s. meliloti 1021 also reveals the orf smc01553, annotated as a putative acp. smc01553 is part of a 6.6 kb dna region that is duplicated in the chromosome and in the psymb plasmid, the result of a recent duplication event. smc01553 overexp ... | 2010 | 19797355 |
| plasmids that insert into the rhamnose utilization locus, rha: a versatile tool for genetic studies in sinorhizobium meliloti. | described is a suite of plasmids that can be used to deliver dna into a specific site in the chromosome of sinorhizobium meliloti with a minimal impact in the physiology of the organism. this allows stable, single-copy, insertions of dna while maintaining a constant chromosomal context. the plasmids integrate into rhas, one of a group of genes encoding proteins for rhamnose utilization, enabling a simple screening method for recombinants, while leaving other cellular processes unaffected by the ... | 2009 | 19797916 |
| expression of small rnas in rhizobiales and protection of a small rna and its degradation products by hfq in sinorhizobium meliloti. | regulatory rna plays a pivotal role in the regulation of bacterial gene expression. here, five small rnas were studied in sinorhizobium meliloti - smrc15, smrc16, sra33, 6s and the signal recognition particle (srp) rna, which are conserved among at least seven different rhizobium and sinorhizobium species. the amount of smrc16 decreased in stationary phase, while the other rnas were up-regulated. the smallest changes, maximally 2-fold, were observed for 6s rna. in the distantly related bradyrhiz ... | 2009 | 19800865 |
| unusual thermal disassembly of the spfh domain oligomer from pyrococcus horikoshii. | stomatin, prohibitin, flotillin, and hflk/c (spfh) domain proteins are membrane proteins that are widely conserved from bacteria to mammals. the molecular functions of these proteins have not been established. in mammals, the domain is often found in raft-associated proteins such as flotillin and podocin. we determined the structure of the spfh domain of ph0470 derived from pyrococcus horikoshii using nmr. the structure closely resembles that of the spfh domain of the paralog ph1511, except for ... | 2009 | 19804735 |
| genetic analysis of the rkp-3 gene region in sinorhizobium meliloti 41: rkpy directs capsular polysaccharide synthesis to kr5 antigen production. | rhizobial surface polysaccharides, including capsular polysaccharides (kps), are involved in symbiotic infection. the rkp-3 locus of sinorhizobium meliloti 41 is responsible for the production of pseudaminic acid, one of the components of the kr5 antigen, a strain-specific kps. we have extended the sequence determination and genetic dissection of the rkp-3 region to clarify the structure and function of the rkpy gene and to identify additional rkp genes. except for rkpy, no other genes were foun ... | 2009 | 19810811 |
| nemesys: a biological resource for narrowing the gap between sequence and function in the human pathogen neisseria meningitidis. | genome sequences, now available for most pathogens, hold promise for the rational design of new therapies. however, biological resources for genome-scale identification of gene function (notably genes involved in pathogenesis) and/or genes essential for cell viability, which are necessary to achieve this goal, are often sorely lacking. this holds true for neisseria meningitidis, one of the most feared human bacterial pathogens that causes meningitis and septicemia. | 2009 | 19818133 |
| deletion of citrate synthase restores growth of sinorhizobium meliloti 1021 aconitase mutants. | the symbiotic nitrogen-fixing bacterium sinorhizobium meliloti 1021 encodes only one predicted aconitase (acna) in its genome. acna has a significant degree of similarity with other bacterial aconitases that behave as dual proteins: enzymes and posttranscriptional regulators of gene expression. similar to the case with these bacterial aconitases, acna activity was reversibly labile and was regained upon reconstitution with reduced iron. the aconitase promoter was active in root nodules. acna mut ... | 2009 | 19820082 |
| tonb-dependent transporters and their occurrence in cyanobacteria. | different iron transport systems evolved in gram-negative bacteria during evolution. most of the transport systems depend on outer membrane localized tonb-dependent transporters (tbdts), a periplasma-facing tonb protein and a plasma membrane localized machinery (exbbd). so far, iron chelators (siderophores), oligosaccharides and polypeptides have been identified as substrates of tbdts. for iron transport, three uptake systems are defined: the lactoferrin/transferrin binding proteins, the porphyr ... | 2009 | 19821963 |
| [effect of placement of genetic modified strain of sinorhizobium meliloti ach-5 into microbial soil association]. | | 2009 | 19827718 |
| survival of the fittest: how brucella strains adapt to their intracellular niche in the host. | brucella strains produce abortion and infertility in their natural hosts and a zoonotic disease in humans known as undulant fever. these bacteria do not produce classical virulence factors, and their capacity to successfully survive and replicate within a variety of host cells underlies their pathogenicity. extensive replication of the brucellae in placental trophoblasts is associated with reproductive tract pathology in natural hosts, and prolonged persistence in macrophages leads to the chroni ... | 2009 | 19830453 |
| phenotypic and genotypic characterization of rhizobia associated with acacia saligna (labill.) wendl. in nurseries from algeria. | twenty seven rhizobial strains associated with acacia saligna grown in northern and southern algeria were characterized, including generation time, host-range, the 16s rrna gene and 16s-23s rrna intergenic spacer restriction patterns, 16s rrna gene sequence analysis and tolerance to salinity and drought. cross inoculation tests indicated that 11 slow-growing isolates from northern nurseries were able to nodulate introduced australian acacias exclusively, whereas 16 fast-growing isolates, mainly ... | 2010 | 19836181 |
| importance of trehalose biosynthesis for sinorhizobium meliloti osmotolerance and nodulation of alfalfa roots. | the disaccharide trehalose is a well-known osmoprotectant, and trehalose accumulation through de novo biosynthesis is a common response of bacteria to abiotic stress. in this study, we have investigated the role of endogenous trehalose synthesis in the osmotolerance of sinorhizobium meliloti. genes coding for three possible trehalose synthesis pathways are present in the genome of s. meliloti 1021: otsa, treyz, and tres. among these, otsa has a major role in trehalose accumulation under all of t ... | 2009 | 19837796 |
| null mutations in sinorhizobium meliloti exos and chvi demonstrate the importance of this two-component regulatory system for symbiosis. | exopolysaccharides, either succinoglycan or galactoglucan, are essential for the establishment of the symbiosis between sinorhizobium meliloti and medicago sativa (alfalfa). the exos/chvi two-component regulatory system is known as a regulator of succinoglycan production but the genes that are directly regulated by chvi have not been determined. difficulty isolating exos and chvi null mutants has prompted the suggestion that these genes are essential for s. meliloti viability. we have successful ... | 2009 | 19843226 |
| identification of catechin as one of the flavonoids from combretum albiflorum bark extract that reduces the production of quorum-sensing-controlled virulence factors in pseudomonas aeruginosa pao1. | quorum-sensing (qs) regulates the production of key virulence factors in pseudomonas aeruginosa and other important pathogenic bacteria. in this report, extracts of leaves and bark of combretum albiflorum (tul.) jongkind (combretaceae) were found to quench the production of qs-dependent factors in p. aeruginosa pao1. chromatographic fractionation of the crude active extract generated several active fractions containing flavonoids, as shown by their typical spectral features. purification and str ... | 2010 | 19854927 |
| identification of catechin as one of the flavonoids from combretum albiflorum bark extract that reduces the production of quorum-sensing-controlled virulence factors in pseudomonas aeruginosa pao1. | quorum-sensing (qs) regulates the production of key virulence factors in pseudomonas aeruginosa and other important pathogenic bacteria. in this report, extracts of leaves and bark of combretum albiflorum (tul.) jongkind (combretaceae) were found to quench the production of qs-dependent factors in p. aeruginosa pao1. chromatographic fractionation of the crude active extract generated several active fractions containing flavonoids, as shown by their typical spectral features. purification and str ... | 2010 | 19854927 |
| biosynthesis of the proteasome inhibitor syringolin a: the ureido group joining two amino acids originates from bicarbonate. | syringolin a, an important virulence factor in the interaction of the phytopathogenic bacterium pseudomonas syringae pv. syringae b728a with its host plant phaseolus vulgaris (bean), was recently shown to irreversibly inhibit eukaryotic proteasomes by a novel mechanism. syringolin a is synthesized by a mixed non-ribosomal peptide synthetase/polyketide synthetase and consists of a tripeptide part including a twelve-membered ring with an n-terminal valine that is joined to a second valine via a ve ... | 2009 | 19863801 |
| mechanisms and regulation of polar surface attachment in agrobacterium tumefaciens. | agrobacterium tumefaciens is a plant pathogen that transfers a segment of its own dna into host plants to cause crown gall disease. the infection process requires intimate contact between the infecting bacteria and the host tissue. a. tumefaciens attaches efficiently to plant tissues and to abiotic surfaces, and can establish complex biofilms at colonization sites. the dominant mode of attachment is via a single pole in contact with the surface. several different appendages, adhesins and adhesiv ... | 2009 | 19879182 |
| maturation of 23s rrna in bacillus subtilis in the absence of mini-iii. | 23s rrna maturation in bacillus subtilis is catalyzed by the recently characterized enzyme mini-rnase-iii. mini-iii is dispensable, however, and 23s rrna is matured by other ribonucleases in strains lacking this enzyme. here we show that these rnases are the 5'-to-3' exoribonuclease rnase j1 and the 3'-to-5' exoribonucleases, principally rnase ph and yham. | 2010 | 19880604 |
| maturation of 23s rrna in bacillus subtilis in the absence of mini-iii. | 23s rrna maturation in bacillus subtilis is catalyzed by the recently characterized enzyme mini-rnase-iii. mini-iii is dispensable, however, and 23s rrna is matured by other ribonucleases in strains lacking this enzyme. here we show that these rnases are the 5'-to-3' exoribonuclease rnase j1 and the 3'-to-5' exoribonucleases, principally rnase ph and yham. | 2010 | 19880604 |
| the medicago truncatula n5 gene encoding a root-specific lipid transfer protein is required for the symbiotic interaction with sinorhizobium meliloti. | the medicago truncatula n5 gene is induced in roots after sinorhizobium meliloti infection and it codes for a putative lipid transfer protein (ltp), a family of plant small proteins capable of binding and transferring lipids between membranes in vitro. various biological roles for plant ltp in vivo have been proposed, including defense against pathogens and modulation of plant development. the aim of this study was to shed light on the role of mtn5 in the symbiotic interaction between m. truncat ... | 2009 | 19888823 |
| production of succinoglycan polymer in sinorhizobium meliloti is affected by smb21506 and requires the n-terminal domain of exop. | the protein tyrosine kinase exop, consisting of an n-terminal periplasmic and a c-terminal cytoplasmic domain, is important for polymerization of the exopolysaccharide succinoglycan (eps i) in sinorhizobium meliloti. we analyzed the contribution of the exop paralogs exop2 and smb21506 to the production of the high molecular weight (hmw) form of eps i. exop2, though not contributing to eps i or lipopolysaccharide biosynthesis, showed increased expression at high osmolarity and was expressed in me ... | 2009 | 19888830 |
| novel sinorhizobium meliloti quorum sensing positive and negative regulatory feedback mechanisms respond to phosphate availability. | the sin quorum sensing system of sinorhizobium meliloti depends upon at least three genes, sinr, sini and expr, and n-acyl homoserine lactones (ahls) as signals to regulate multiple processes in its free-living state in the rhizosphere and in the development towards symbiosis with its plant host. in this study, we have characterized novel mechanisms of transcription control through which the system regulates itself. at low ahl levels a positive feedback loop activates expression of sini (ahl syn ... | 2009 | 19889097 |
| structure of dihydropyrimidinase from sinorhizobium meliloti cect4114: new features in an amidohydrolase family member. | the recombinant dihydropyrimidinase from sinorhizobium meliloti cect4114 (smeldhp) has been characterised and its crystal structure elucidated at 1.85a. the global architecture of the protein is reminiscent of that of the amidohydrolase superfamily, consisting of two domains; an (alpha/beta)(8) tim-like barrel domain, where the catalytic centre is located, and a smaller beta-sheet sandwich domain of unknown function. the c-terminal tails of each subunit extend toward another monomer in a swappin ... | 2010 | 19895890 |
| differential gel electrophoresis (dige) to quantitatively monitor early symbiosis- and pathogenesis-induced changes of the medicago truncatula root proteome. | symbiosis- and pathogenesis-related early protein induction patterns in the model legume medicago truncatula were analysed with two-dimensional differential gel electrophoresis. two symbiotic soil microorganisms (glomus intraradices, sinorhizobium meliloti) were used in single infections and in combination with a secondary pathogenic infection by the oomycete aphanomyces euteiches. proteomic analyses performed 6 and 24h after inoculations led to identification of 87 differentially induced protei ... | 2010 | 19895911 |
| nodule-enhanced expression of a sucrose phosphate synthase gene member (msspsa) has a role in carbon and nitrogen metabolism in the nodules of alfalfa (medicago sativa l.). | sucrose phosphate synthase (sps) catalyzes the first step in the synthesis of sucrose in photosynthetic tissues. we characterized the expression of three different isoforms of sps belonging to two different sps gene families in alfalfa (medicago sativa l.), a previously identified sps (msspsa) and two novel isoforms belonging to class b (msspsb and msspsb3). while msspsa showed nodule-enhanced expression, both msspsb genes exhibited leaf-enhanced expression. alfalfa leaf and nodule sps enzymes s ... | 2010 | 19898977 |
| nodule-enhanced expression of a sucrose phosphate synthase gene member (msspsa) has a role in carbon and nitrogen metabolism in the nodules of alfalfa (medicago sativa l.). | sucrose phosphate synthase (sps) catalyzes the first step in the synthesis of sucrose in photosynthetic tissues. we characterized the expression of three different isoforms of sps belonging to two different sps gene families in alfalfa (medicago sativa l.), a previously identified sps (msspsa) and two novel isoforms belonging to class b (msspsb and msspsb3). while msspsa showed nodule-enhanced expression, both msspsb genes exhibited leaf-enhanced expression. alfalfa leaf and nodule sps enzymes s ... | 2010 | 19898977 |
| the phob regulatory system modulates biofilm formation and stress response in el tor biotype vibrio cholerae. | the phobr regulatory system is required for the induction of multiple genes under conditions of phosphate limitation. here, we examine the role of phob in biofilm formation and environmental stress response in vibrio cholerae of the el tor biotype. deletion of phob or hapr enhanced biofilm formation in a phosphate-limited medium. planktonic and redispersed biofilm cells of the deltaphob mutant did not differ from wild type for the expression of hapr, suggesting that phob negatively affects biofi ... | 2010 | 19909344 |
| the phob regulatory system modulates biofilm formation and stress response in el tor biotype vibrio cholerae. | the phobr regulatory system is required for the induction of multiple genes under conditions of phosphate limitation. here, we examine the role of phob in biofilm formation and environmental stress response in vibrio cholerae of the el tor biotype. deletion of phob or hapr enhanced biofilm formation in a phosphate-limited medium. planktonic and redispersed biofilm cells of the deltaphob mutant did not differ from wild type for the expression of hapr, suggesting that phob negatively affects biofi ... | 2010 | 19909344 |
| metabolic fluxes during strong carbon catabolite repression by malate in bacillus subtilis. | commonly glucose is considered to be the only preferred substrate in bacillus subtilis whose presence represses utilization of other alternative substrates. because recent data indicate that malate might be an exception, we quantify here the carbon source utilization hierarchy. based on physiology and transcriptional data during co-utilization experiments with eight carbon substrates, we demonstrate that malate is a second preferred carbon source for b. subtilis, which is rapidly co-utilized wit ... | 2010 | 19917605 |
| metabolic fluxes during strong carbon catabolite repression by malate in bacillus subtilis. | commonly glucose is considered to be the only preferred substrate in bacillus subtilis whose presence represses utilization of other alternative substrates. because recent data indicate that malate might be an exception, we quantify here the carbon source utilization hierarchy. based on physiology and transcriptional data during co-utilization experiments with eight carbon substrates, we demonstrate that malate is a second preferred carbon source for b. subtilis, which is rapidly co-utilized wit ... | 2010 | 19917605 |
| the atp-binding cassette transporter cbc (choline/betaine/carnitine) recruits multiple substrate-binding proteins with strong specificity for distinct quaternary ammonium compounds. | we identified a choline, betaine and carnitine transporter, designated cbc, from pseudomonas syringae and pseudomonas aeruginosa that is unusual among members of the atp-binding cassette (abc) transporter family in its use of multiple periplasmic substrate-binding proteins (sbps) that are highly specific for their substrates. the sbp encoded by the cbcxwv operon, cbcx, binds choline with a high affinity (k(m), 2.6 microm) and, although it also binds betaine (k(m), 24.2 microm), cbcxwv-mediated b ... | 2010 | 19919675 |
| analysis of the mucr gene regulating biosynthesis of exopolysaccharides: implications for biofilm formation in sinorhizobium meliloti rm1021. | bacterial surface polysaccharides are crucial for establishment of successful rhizobia-legume symbiosis, and in most bacteria, are also critical for biofilm formation and surface colonization. in sinorhizobium meliloti, the regulatory protein mucr controls exopolysaccharide production. to clarify the relationship between exopolysaccharide synthesis and biofilm formation, we studied mucr expression under growth conditions that influence attachment to polyvinylchloride, developed a microtiter plat ... | 2010 | 19929968 |
| gene smb21071 of plasmid psymb is required for osmoadaptation of sinorhizobium meliloti 1021 and is implicated in modifications of cell surface polysaccharides structure in response to hyperosmotic stress. | megaplasmid psymb of the nitrogen-fixing symbiont sinorhizobium meliloti, implicated in adaptation to hyperosmotic stress, contains 11 gene clusters that apparently encode surface polysaccharides. however, only 2 of these clusters, containing the exo and exp genes, have been associated with the synthesis of the acidic exopolysaccharides succinoglycan and galactoglucan, respectively. the functions of the other 9 clusters remain unsolved. the involvement of one of those regions, psymb cluster 3, o ... | 2009 | 19935886 |
| strain competition and agar affect the interaction of rhizobia with rice. | competition assays with sinorhizobium meliloti 1021 and its gfp-labelled psyma cured and deleted derivatives, sma818 and sma146, demonstrated that sm1021 could still inhibit rice seedling growth even when outnumbered by a large excess of the noninhibitory cured or deleted strain. the wild-type strain sm1021 also inhibited the growth of its noninhibitory psyma-cured strain sma818(gfp) and its psyma-deleted strain sma146(gfp) in a manner suggesting that sm1021 produced a bacteriocin-like substance ... | 2009 | 19935894 |
| genome variation in the symbiotic nitrogen-fixing bacterium sinorhizobium meliloti. | differences in genome size and gene content are among the most important signatures of microbial adaptation and genome evolution. here, we investigated the patterns of genome variation among 10 natural strains of the symbiotic nitrogen-fixing bacterium sinorhizobium meliloti, using pulse field gel electrophoresis (pfge) and whole-genome microarray hybridizations. our pfge analysis showed a genome size range of 6.45-7.01 mbp, with the greatest variation arising from the psyma replicon, followed b ... | 2009 | 19935910 |
| distribution of cepacian biosynthesis genes among environmental and clinical burkholderia strains and role of cepacian exopolysaccharide in resistance to stress conditions. | the genus burkholderia includes strains pathogenic to animals and plants, bioremediators, or plant growth promoters. genome sequence analyses of representative burkholderia cepacia complex (bcc) and non-bcc strains for the presence of the bce-i gene cluster, directing the biosynthesis of the exopolysaccharide (eps) cepacian, further extended this previously described cluster by another 9 genes. the genes in the bce-ii cluster were named bcem to bceu and encode products putatively involved in nuc ... | 2010 | 19948863 |
| distribution of cepacian biosynthesis genes among environmental and clinical burkholderia strains and role of cepacian exopolysaccharide in resistance to stress conditions. | the genus burkholderia includes strains pathogenic to animals and plants, bioremediators, or plant growth promoters. genome sequence analyses of representative burkholderia cepacia complex (bcc) and non-bcc strains for the presence of the bce-i gene cluster, directing the biosynthesis of the exopolysaccharide (eps) cepacian, further extended this previously described cluster by another 9 genes. the genes in the bce-ii cluster were named bcem to bceu and encode products putatively involved in nuc ... | 2010 | 19948863 |
| structural features in the c-terminal region of the sinorhizobium meliloti rmint1 group ii intron-encoded protein contribute to its maturase and intron dna-insertion function. | group ii introns are both catalytic rnas and mobile retroelements that move through a process catalyzed by a rnp complex consisting of an intron-encoded protein and the spliced intron lariat rna. group ii intron-encoded proteins are multifunctional and contain an n-terminal reverse transcriptase domain, followed by a putative rna-binding domain (domain x) associated with rna splicing or maturase activity and a c-terminal dna binding/dna endonuclease region. the intron-encoded protein encoded by ... | 2010 | 19951359 |
| posttranslational control of transcription factor fixk2, a key regulator for the bradyrhizobium japonicum-soybean symbiosis. | rhizobial fixk-like proteins play essential roles in activating genes for endosymbiotic life in legume root nodules, such as genes for micro-oxic respiration. in the facultative soybean symbiont, bradyrhizobium japonicum, the fixk(2) protein is the key player in a complex regulatory network. the fixk(2) gene itself is activated by the 2-component regulatory system fixlj in response to a moderate decrease of the oxygen tension, and the fixk(2) protein distributes and amplifies this response to th ... | 2009 | 19955406 |
| cultural conditions required for the induction of an adaptive acid-tolerance response (atr) in sinorhizobium meliloti and the question as to whether or not the atr helps rhizobia improve their symbiosis with alfalfa at low ph. | sinorhizobium meliloti associates with medicago and melilotus species to develop nitrogen-fixing symbioses. the agricultural relevance of these associations, the worldwide distribution of acid soils, and the remarkable acid sensitivity of the microsymbiont have all stimulated research on the responses of the symbionts to acid environments. we show here that an adaptive acid-tolerance response (atr) can be induced in s. meliloti, as shown previously for sinorhizobium medicae, when the bacteria ar ... | 2010 | 19958387 |
| the low-affinity phosphate transporter pita is dispensable for in vitro growth of mycobacterium smegmatis. | mycobacteria have been shown to contain an apparent redundancy of high-affinity phosphate uptake systems, with two to four copies of such systems encoded in all mycobacterial genomes sequenced to date. in addition, all mycobacteria also contain at least one gene encoding the low-affinity phosphate transporter, pit. no information is available on a pit system from a gram-positive microorganism, and the importance of this system in a background of multiple other phosphate transporters is unclear. | 2009 | 20003273 |
| identification of flavone phytoalexins and a pathogen-inducible flavone synthase ii gene (sbfnsii) in sorghum. | following inoculation with the anthracnose pathogen colletotrichum sublineolum, seedlings of the sorghum resistant cultivar sc748-5 showed more rapid and elevated accumulation of luteolin than the susceptible cultivar btx623. on the other hand, apigenin was the major flavone detected in infected btx623 seedlings. luteolin was demonstrated to show stronger inhibition of spore germination of c. sublineolum than apigenin. because of their pathogen-inducible and antifungal nature, both flavone aglyc ... | 2010 | 20007684 |
| identification of flavone phytoalexins and a pathogen-inducible flavone synthase ii gene (sbfnsii) in sorghum. | following inoculation with the anthracnose pathogen colletotrichum sublineolum, seedlings of the sorghum resistant cultivar sc748-5 showed more rapid and elevated accumulation of luteolin than the susceptible cultivar btx623. on the other hand, apigenin was the major flavone detected in infected btx623 seedlings. luteolin was demonstrated to show stronger inhibition of spore germination of c. sublineolum than apigenin. because of their pathogen-inducible and antifungal nature, both flavone aglyc ... | 2010 | 20007684 |
| a variety of regulatory mechanisms are involved in the nitrogen-dependent modulation of the nodule organogenesis program in legume roots. | combined nitrogen (n) sources are known to strongly affect initiation, development and functioning of nitrogen-fixing-nodules whose formation is triggered by lipochitin-oligosaccharide signals secreted in the rhizospere by the rhizobium partner. the rapid effects of n supply on nodule initiation have been mainly described when n sources are present at the moment of rhizobium inoculation or purified nod factors addition. we recently reported that high ammonium nitrate growth conditions might also ... | 2009 | 20009551 |