| evolution of the antibiotic resistance protein, fosa, is linked to a catalytically promiscuous progenitor. | the fosfomycin (1) resistance proteins fosa and fosx in pathogenic microorganisms are related to a catalytically promiscuous progenitor encoded in a phn operon in mesorhizobium loti. the mlr3345 gene product (fosx(ml)) from m. loti has a very low epoxide hydrolase activity and even lower glutathione transferase activity toward 1 and does not confer resistance to the antibiotic. in vitro homologous recombination of the mlr3345 and pa1129 genes (a fosa gene from pseudomonas aeruginosa that does co ... | 2009 | 19196010 |
| gene identification and characterization of 5-formyl-3-hydroxy-2-methylpyridine 4-carboxylic acid 5-dehydrogenase, an nad+-dependent dismutase. | a chromosomal gene, mlr6793, in mesorhizobium loti was identified as the gene encoding 5-formyl-3-hydroxy-2-methylpyridine 4-carboxylic acid (fhmpc) dehydrogenase (dismutase) involved in the degradation pathway for pyridoxine (vitamin b(6)). the homogenously purified recombinant enzyme has a molecular mass of 59.1 kda and is a homodimeric protein. fhmpc dehydrogenase catalyses practically irreversible oxidation (k(cat) = 204 s(-1)) of fhmpc (k(m) = 48.2 microm) by nad(+) (k(m) = 34.3 microm) to ... | 2009 | 19218190 |
| characterization of a mesorhizobium loti alpha-type carbonic anhydrase and its role in symbiotic nitrogen fixation. | carbonic anhydrase (ca) (ec 4.2.1.1) is a widespread enzyme catalyzing the reversible hydration of co(2) to bicarbonate, a reaction that participates in many biochemical and physiological processes. mesorhizobium loti, the microsymbiont of the model legume lotus japonicus, possesses on the symbiosis island a gene (msi040) encoding an alpha-type ca homologue, annotated as caa1. in the present work, the caa1 open reading frame from m. loti strain r7a was cloned, expressed, and biochemically charac ... | 2009 | 19218391 |
| genome sequences of three agrobacterium biovars help elucidate the evolution of multichromosome genomes in bacteria. | the family rhizobiaceae contains plant-associated bacteria with critical roles in ecology and agriculture. within this family, many rhizobium and sinorhizobium strains are nitrogen-fixing plant mutualists, while many strains designated as agrobacterium are plant pathogens. these contrasting lifestyles are primarily dependent on the transmissible plasmids each strain harbors. members of the rhizobiaceae also have diverse genome architectures that include single chromosomes, multiple chromosomes, ... | 2009 | 19251847 |
| identification of a novel udp-n-acetylglucosamine enolpyruvyl transferase (mura) from vibrio fischeri that confers high fosfomycin resistance in escherichia coli. | mura [udp-n-acetylglucosamine (udp-nag) enolpyruvyl transferase] is a key enzyme involved in bacterial cell wall peptidoglycan synthesis and a target for the antimicrobial agent fosfomycin, a structural analog of the mura substrate phosphoenol pyruvate. in this study, we identified, cloned and sequenced a novel mura gene from an environmental isolate of vibrio fischeri that is naturally resistant to fosfomycin. the fosfomycin resistance gene was isolated from a genomic dna library of v. fischeri ... | 2009 | 19277606 |
| localization of the attachment site of oligoglucans to mesorhizobium loti hambi 1148 murein. | the location and nature of the linkage between peptidoglycan and oligoglucans in the cell wall of mesorhizobium loti hambi 1148 have been defined by the analysis of nitrous acid deamination of peptidoglycan glucosaminyl residues. the murnh(2)-glc(n) fraction was obtained after converting deaminoacylated and n-deacetylated muramyl residues in the cell wall preparation to lactam forms which were stable during subsequent deamination, followed by reduction and opening of the lactams. gc/ms analysis ... | 2009 | 19294234 |
| functional analysis of three ahl autoinducer synthase genes in mesorhizobium loti reveals the important role of quorum sensing in symbiotic nodulation. | one of the most important signal transduction pathways in bacteria, quorum sensing, is involved in many regulatory circuits in rhizobia, especially in the control of communication between rhizobia and their plant hosts. in this study, we identified 3 autoinducer synthase genes - mrli1, mrli2, and mrli3 - in mesorhizobium loti nzp 2213. we found that mrli1 and mrli2 could synthesize distinct n-acyl homoserine lactone (ahl) autoinducers in rich medium cultures, and the expression of mrli1 was show ... | 2009 | 19295655 |
| the mnth gene encodes the major mn(2+) transporter in bradyrhizobium japonicum and is regulated by manganese via the fur protein. | the bacterial nramp family protein mnth is a divalent metal transporter, but mnth mutants have little or no phenotype in organisms where it has been studied. here, we identify the mnth homologue of bradyrhizobium japonicum, and demonstrate that it is essential for mn(2+) transport and for maintenance of cellular manganese homeostasis. transport activity was induced under manganese deficiency, and fe(2+) did not compete with (54)mn(2+) for uptake by cells. the steady-state level of mnth mrna was ... | 2009 | 19298371 |
| structure of the plp degradative enzyme 2-methyl-3-hydroxypyridine-5-carboxylic acid oxygenase from mesorhizobium loti maff303099 and its mechanistic implications. | a vitamin b(6) degradative pathway has recently been identified and characterized in mesorhizobium loti maff303099. one of the enzymes on this pathway, 2-methyl-3-hydroxypyridine-5-carboxylic acid oxygenase (mhpco), is a flavin-dependent enzyme and catalyzes the oxidative ring-opening of 2-methyl-3-hydroxypyridine-5-carboxylic acid to form e-2-(acetamino-methylene)succinate. the gene for this enzyme has been cloned, and the corresponding protein has been overexpressed in escherichia coli and pur ... | 2009 | 19317437 |
| developmental gene expression profiles of the human pathogen schistosoma japonicum. | the schistosome blood flukes are complex trematodes and cause a chronic parasitic disease of significant public health importance worldwide, schistosomiasis. their life cycle is characterised by distinct parasitic and free-living phases involving mammalian and snail hosts and freshwater. microarray analysis was used to profile developmental gene expression in the asian species, schistosoma japonicum. total rnas were isolated from the three distinct environmental phases of the lifecycle -- aquati ... | 2009 | 19320991 |
| analysis of ten brucella genomes reveals evidence for horizontal gene transfer despite a preferred intracellular lifestyle. | the facultative intracellular bacterial pathogen brucella infects a wide range of warm-blooded land and marine vertebrates and causes brucellosis. currently, there are nine recognized brucella species based on host preferences and phenotypic differences. the availability of 10 different genomes consisting of two chromosomes and representing six of the species allowed for a detailed comparison among themselves and relatives in the order rhizobiales. phylogenomic analysis of ortholog families show ... | 2009 | 19346311 |
| characterization of the mesorhizobium loti maff303099 type-three protein secretion system. | type iii secretion systems (t3ss) have been found in several species of rhizobia. proteins (termed effectors) secreted by this system are involved in host-range determination and influence nodulation efficiency. mesorhizobium loti maff303099 possesses a functional t3ss in its symbiotic island whose expression is induced by flavonoids. as in other rhizobia, conserved cis-elements (tts box) were found in the promoter regions of genes or operons encoding t3ss components. using a bioinformatics appr ... | 2009 | 19348570 |
| the structural role of the zinc ion can be dispensable in prokaryotic zinc-finger domains. | the recent characterization of the prokaryotic cys(2)his(2) zinc-finger domain, identified in ros protein from agrobacterium tumefaciens, has demonstrated that, although possessing a similar zinc coordination sphere, this domain is structurally very different from its eukaryotic counterpart. a search in the databases has identified approximately 300 homologues with a high sequence identity to the ros protein, including the amino acids that form the extensive hydrophobic core in ros. surprisingly ... | 2009 | 19369210 |
| transcriptomic analysis of rhizobium leguminosarum biovar viciae in symbiosis with host plants pisum sativum and vicia cracca. | rhizobium leguminosarum bv. viciae forms nitrogen-fixing nodules on several legumes, including pea (pisum sativum) and vetch (vicia cracca), and has been widely used as a model to study nodule biochemistry. to understand the complex biochemical and developmental changes undergone by r. leguminosarum bv. viciae during bacteroid development, microarray experiments were first performed with cultured bacteria grown on a variety of carbon substrates (glucose, pyruvate, succinate, inositol, acetate, a ... | 2009 | 19376875 |
| rhizobium sp. strain ngr234 possesses a remarkable number of secretion systems. | rhizobium sp. strain ngr234 is a unique alphaproteobacterium (order rhizobiales) that forms nitrogen-fixing nodules with more legumes than any other microsymbiont. we report here that the 3.93-mbp chromosome (cngr234) encodes most functions required for cellular growth. few essential functions are encoded on the 2.43-mbp megaplasmid (pngr234b), and none are present on the second 0.54-mbp symbiotic plasmid (pngr234a). among many striking features, the 6.9-mbp genome encodes more different secreti ... | 2009 | 19376903 |
| extensive genomic diversity of closely related wolbachia strains. | using microarray-based comparative genome hybridization (mcgh), the genomic content of wolbachia pipientis wmel from drosophila melanogaster was compared to the closely related wolbachia from d. innubila (winn), d. santomea (wsan), and three strains from d. simulans (wau, wri, wsim). a large number of auxiliary genes are identified in these five strains, with most absent/divergent genes being unique to a given strain. each strain caused an average of approximately 60 genes to be removed from the ... | 2009 | 19389774 |
| molecular and biochemical characterization of the parvulin-type ppiases in lotus japonicus. | the cis/trans isomerization of the peptide bond preceding proline is an intrinsically slow process, although important in many biological processes in both prokaryotes and eukaryotes. in vivo, this isomerization is catalyzed by peptidyl-prolyl cis/trans-isomerases (ppiases). here, we present the molecular and biochemical characterization of parvulin-type ppiase family members of the model legume lotus japonicus, annotated as ljpar1, ljpar2, and ljpar3. although ljpar1 and ljpar2 were found to be ... | 2009 | 19403733 |
| an acetyltransferase conferring tolerance to toxic aromatic amine chemicals: molecular and functional studies. | aromatic amines (aa) are a major class of environmental pollutants that have been shown to have genotoxic and cytotoxic potentials toward most living organisms. fungi are able to tolerate a diverse range of chemical compounds including certain aa and have long been used as models to understand general biological processes. deciphering the mechanisms underlying this tolerance may improve our understanding of the adaptation of organisms to stressful environments and pave the way for novel pharmace ... | 2009 | 19416981 |
| evolution in the amidohydrolase superfamily: substrate-assisted gain of function in the e183k mutant of a phosphotriesterase-like metal-carboxylesterase. | the recent specialization for utilization of pesticides reported for pseudomonas diminuta phosphotriesterase (ppte) strongly suggests that this activity evolved from an enzyme endowed with promiscuous phosphotriesterase activity. such a putative "generalist" enzyme was recently proposed to be a member of the new phoshotriesterase-like lactonase family (pll). the promiscuous carboxylesterase and phosphodiesterase activities detected in ppte and plls in turn paved the way for the prediction of the ... | 2009 | 19438255 |
| methylobacterium genome sequences: a reference blueprint to investigate microbial metabolism of c1 compounds from natural and industrial sources. | methylotrophy describes the ability of organisms to grow on reduced organic compounds without carbon-carbon bonds. the genomes of two pink-pigmented facultative methylotrophic bacteria of the alpha-proteobacterial genus methylobacterium, the reference species methylobacterium extorquens strain am1 and the dichloromethane-degrading strain dm4, were compared. | 2009 | 19440302 |
| nicotianamine synthase specifically expressed in root nodules of lotus japonicus. | in dicotyledonous plants, nicotianamine synthase (nas) is thought to play a role in the intercellular transport of iron (fe). fe is an essential metal for nitrogen-fixing root nodules of legumes, prompting us to characterize the role of the nas gene in detail. we previously compared gene-expression profiles in ineffective nodules formed on a lotus japonicus fix(-) mutant, sen1, with those in wild-type-effective nodules, and showed that expression of an expressed sequence tag (est) clone encoding ... | 2009 | 19455352 |
| solution structure of the mesorhizobium loti k1 channel cyclic nucleotide-binding domain in complex with camp. | cyclic nucleotide-sensitive ion channels, known as hcn and cng channels, are crucial in neuronal excitability and signal transduction of sensory cells. hcn and cng channels are activated by binding of cyclic nucleotides to their intracellular cyclic nucleotide-binding domain (cnbd). however, the mechanism by which the binding of cyclic nucleotides opens these channels is not well understood. here, we report the solution structure of the isolated cnbd of a cyclic nucleotide-sensitive k(+) channel ... | 2009 | 19465888 |
| a cytosolic invertase is required for normal growth and cell development in the model legume, lotus japonicus. | neutral/alkaline invertases are a subgroup, confined to plants and cyanobacteria, of a diverse family of enzymes. a family of seven closely-related genes, ljinv1-ljinv7, is described here and their expression in the model legume, lotus japonicus, is examined. ljinv1 previously identified as encoding a nodule-enhanced isoform is the predominant isoform present in all parts of the plant. mutants for two isoforms, ljinv1 and ljinv2, were isolated using tilling. a premature stop codon allele of ljin ... | 2009 | 19474088 |
| ensifer meliloti bv. lancerottense establishes nitrogen-fixing symbiosis with lotus endemic to the canary islands and shows distinctive symbiotic genotypes and host range. | eleven strains were isolated from root nodules of lotus endemic to the canary islands and they belonged to the genus ensifer, a genus never previously described as a symbiont of lotus. according to their 16s rrna and atpd gene sequences, two isolates represented minority genotypes that could belong to previously undescribed ensifer species, but most of the isolates were classified within the species ensifer meliloti. these isolates nodulated lotus lancerottensis, lotus corniculatus and lotus jap ... | 2009 | 19477097 |
| symbiotic competence in lotus japonicus is affected by plant nitrogen status: transcriptomic identification of genes affected by a new signalling pathway. | in leguminous plants, symbiotic nitrogen (n) fixation performances and n environmental conditions are linked because nodule initiation, development and functioning are greatly influenced by the amount of available n sources. we demonstrate here that n supply also controls, beforehand, the competence of leguminous plants to perform the nodulation program. lotus japonicus plants preincubated for 10 d in high-n conditions, and then transferred to low n before the mesorhizobium loti inoculation, had ... | 2009 | 19500268 |
| ethylene insensitivity conferred by a mutated arabidopsis ethylene receptor gene alters nodulation in transgenic lotus japonicus. | transgenics are used to demonstrate a causal relationship between ethylene insensitivity of a seedling legume plant, the level of ethylene receptor gene expression, lateral root growth and mesorhizobium loti-induced nodule initiation. | 2009 | 19505874 |
| cerberus, a novel u-box protein containing wd-40 repeats, is required for formation of the infection thread and nodule development in the legume-rhizobium symbiosis. | endosymbiotic infection of legume plants by rhizobium bacteria is initiated through infection threads (its) which are initiated within and penetrate from root hairs and deliver the endosymbionts into nodule cells. despite recent progress in understanding the mutual recognition and early symbiotic signaling cascades in host legumes, the molecular mechanisms underlying bacterial infection processes and successive nodule organogenesis are still poorly understood. we isolated a novel symbiotic mutan ... | 2009 | 19508425 |
| cytokinin induces expansin gene expression in melilotus alba desr. wild-type and the non-nodulating, non-mycorrhizal (nodmyc) mutant masym3. | we previously showed that applying 10(-6) m of the cytokinin 6-benzylaminopurine (bap) to uninoculated roots of masym3, a nod(-)myc(-)melilotus alba (desr.) mutant, resulted in the accumulation of maenod40 transcripts to levels similar to bap-treated wild-type roots. in contrast, inoculation with a nod(-)s. meliloti mutant expressing the trans-zeatin synthase gene of agrobacterium tumefaciens (nod(-)/ptzs(+)) did not induce maenod40 transcript accumulation in either wild-type or masym3 roots. ho ... | 2008 | 19513217 |
| the symbiosis interactome: a computational approach reveals novel components, functional interactions and modules in sinorhizobium meliloti. | rhizobium-legume symbiosis is an attractive biological process that has been studied for decades because of its importance in agriculture. however, this system has undergone extensive study and although many of the major factors underpinning the process have been discovered using traditional methods, much remains to be discovered. | 2009 | 19531251 |
| fine-structured multi-scaling long-range correlations in completely sequenced genomes--features, origin, and classification. | the sequential organization of genomes, i.e. the relations between distant base pairs and regions within sequences, and its connection to the three-dimensional organization of genomes is still a largely unresolved problem. long-range power-law correlations were found using correlation analysis on almost the entire observable scale of 132 completely sequenced chromosomes of 0.5 x 10(6) to 3.0 x 10(7) bp from archaea, bacteria, arabidopsis thaliana, saccharomyces cerevisiae, schizosaccharomyces po ... | 2009 | 19533117 |
| the complete genome of teredinibacter turnerae t7901: an intracellular endosymbiont of marine wood-boring bivalves (shipworms). | here we report the complete genome sequence of teredinibacter turnerae t7901. t. turnerae is a marine gamma proteobacterium that occurs as an intracellular endosymbiont in the gills of wood-boring marine bivalves of the family teredinidae (shipworms). this species is the sole cultivated member of an endosymbiotic consortium thought to provide the host with enzymes, including cellulases and nitrogenase, critical for digestion of wood and supplementation of the host's nitrogen-deficient diet. t. t ... | 2009 | 19568419 |
| 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 |
| persistent wolbachia and cultivable bacteria infection in the reproductive and somatic tissues of the mosquito vector aedes albopictus. | commensal and symbiotic microbes have a considerable impact on the behavior of many arthropod hosts, including hematophagous species that transmit pathogens causing infectious diseases to human and animals. little is known about the bacteria associated with mosquitoes other than the vectorized pathogens. this study investigated wolbachia and cultivable bacteria that persist through generations in ae. albopictus organs known to host transmitted arboviruses, such as dengue and chikungunya. | 2009 | 19633721 |
| resonance assignment of the cyclic nucleotide binding domain from a cyclic nucleotide-gated k(+) channel in complex with camp. | in order to determine the structure of the 15 kda cyclic nucleotide binding domain of a cyclic nucleotide-activated k(+) channel from mesorhizobium loti and its interaction with camp, nearly complete (1)h, (13)c, and (15)n chemical shifts were assigned. | 2007 | 19636859 |
| mesorhizobium shangrilense sp. nov., isolated from root nodules of caragana species. | five strains of bacteria isolated from nodules of caragana bicolor and caragana erinacea in yunnan province of china were classified within the genus mesorhizobium in the class alphaproteobacteria. the highest degree of 16s rrna gene sequence similarity was determined to be to mesorhizobium loti lmg 6125(t) (99.7 %) and mesorhizobium ciceri upm-ca7(t) (99.7 %). polyphasic taxonomic methods including sds-page of whole-cell soluble proteins, comparative housekeeping sequence analysis of atpd, glni ... | 2009 | 19643905 |
| crystallization and preliminary x-ray analysis of aams amidohydrolase, the final enzyme in degradation pathway i of pyridoxine. | alpha-(n-acetylaminomethylene)succinic acid (aams) amidohydrolase from mesorhizobium loti maff303099, which is involved in a degradation pathway of vitamin b(6) and catalyzes the degradation of aams to acetic acid, ammonia, carbon dioxide and succinic semialdehyde, has been overexpressed in escherichia coli. to elucidate the reaction mechanism based on the tertiary structure, the recombinant enzyme was purified and crystallized by the sitting-drop vapour-diffusion method using peg 8000 as precip ... | 2009 | 19652351 |
| dissection of symbiosis and organ development by integrated transcriptome analysis of lotus japonicus mutant and wild-type plants. | genetic analyses of plant symbiotic mutants has led to the identification of key genes involved in rhizobium-legume communication as well as in development and function of nitrogen fixing root nodules. however, the impact of these genes in coordinating the transcriptional programs of nodule development has only been studied in limited and isolated studies. here, we present an integrated genome-wide analysis of transcriptome landscapes in lotus japonicus wild-type and symbiotic mutant plants. enc ... | 2009 | 19662091 |
| chelativorans multitrophicus gen. nov., sp. nov. and chelativorans oligotrophicus sp. nov., aerobic edta-degrading bacteria. | two previously isolated strains (dsm 9103(t) and lpm-4(t)) able to grow with edta (facultatively and obligately, respectively) as the source of carbon, nitrogen and energy were investigated in order to clarify their taxonomic positions. the strains were strictly aerobic, gram-negative, asporogenous and non-motile rods that required biotin for growth. reproduction occurred by binary fission. the strains were mesophilic and neutrophilic. their major fatty acids were summed feature 7 (consisting of ... | 2010 | 19666787 |
| 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 |
| a luxri-family regulatory system controls excision and transfer of the mesorhizobium loti strain r7a symbiosis island by activating expression of two conserved hypothetical genes. | the symbiosis island icemlsym(r7a) of mesorhizobium loti r7a is an integrative and conjugative element (ice) that carries genes required for a nitrogen-fixing symbiosis with lotus species. icemlsym(r7a) encodes homologues (trar, trai1 and trai2) of proteins that regulate plasmid transfer by quorum sensing in rhizobia and agrobacteria. introduction of trar cloned on a plasmid induced excision of icemlsym(r7a) in all cells, a 1000-fold increase in the production of 3-oxo-c6-homoserine lactone (3-o ... | 2009 | 19682258 |
| prokaryotic homologs of argonaute proteins are predicted to function as key components of a novel system of defense against mobile genetic elements. | in eukaryotes, rna interference (rnai) is a major mechanism of defense against viruses and transposable elements as well of regulating translation of endogenous mrnas. the rnai systems recognize the target rna molecules via small guide rnas that are completely or partially complementary to a region of the target. key components of the rnai systems are proteins of the argonaute-piwi family some of which function as slicers, the nucleases that cleave the target rna that is base-paired to a guide r ... | 2009 | 19706170 |
| 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 |
| epigenetic modification of rhizobial genome is essential for efficient nodulation. | ccrm is one of the solitary bacterial dna methyltransferases which does not have corresponding restriction enzymes. we established a stable ccrm-overexpressing mutant of mesorhizobium loti, mlccrm-ox, and performed molecular and phenotypic characterization of this strain. in the m. loti mlccrm-ox infected plants, nodulation was apparently delayed at 7 days after inoculation (dai), however, the nodules that eventually formed on the mlccrm-ox roots showed nitrogen fixing ability by at least 21 dai ... | 2009 | 19720053 |
| a possible role of class 1 plant hemoglobin at the early stage of legume-rhizobium symbiosis. | | 2009 | 19721749 |
| crystallization and preliminary x-ray analysis of 4-pyridoxolactonase from mesorhizobium loti. | 4-pyridoxolactonase from mesorhizobium loti maff303099 has been overexpressed in escherichia coli. the recombinant enzyme was purified and was crystallized by the sitting-drop vapour-diffusion method using peg 4000 and ammonium sulfate as precipitants. crystals of the free enzyme (form i) and of the 5-pyridoxolactone-bound enzyme (form ii) grew under these conditions. crystals of form i diffracted to 2.0 a resolution and belonged to the monoclinic space group c2, with unit-cell parameters a = 77 ... | 2009 | 19724124 |
| the dif/xer recombination systems in proteobacteria. | in e. coli, 10 to 15% of growing bacteria produce dimeric chromosomes during dna replication. these dimers are resolved by xerc and xerd, two tyrosine recombinases that target the 28-nucleotide motif (dif) associated with the chromosome's replication terminus. in streptococci and lactococci, an alternative system is composed of a unique, xer-like recombinase (xers) genetically linked to a dif-like motif (dif(sl)) located at the replication terminus. preliminary observations have suggested that t ... | 2009 | 19727445 |
| 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 |
| 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 |
| 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 |
| evidence for calcium-mediated perception of plant symbiotic signals in aequorin-expressing mesorhizobium loti. | during the interaction between rhizobia and leguminous plants the two partners engage in a molecular conversation that leads to reciprocal recognition and ensures the beginning of a successful symbiotic integration. in host plants, intracellular ca(2+) changes are an integral part of the signalling mechanism. in rhizobia it is not yet known whether ca(2+) can act as a transducer of symbiotic signals. | 2009 | 19775463 |
| enhanced nodulation and nitrogen fixation in the abscisic acid low-sensitive mutant enhanced nitrogen fixation1 of lotus japonicus. | the phytohormone abscisic acid (aba) is known to be a negative regulator of legume root nodule formation. by screening lotus japonicus seedlings for survival on an agar medium containing 70 microm aba, we obtained mutants that not only showed increased root nodule number but also enhanced nitrogen fixation. the mutant was designated enhanced nitrogen fixation1 (enf1) and was confirmed to be monogenic and incompletely dominant. the low sensitivity to aba phenotype was thought to result from eithe ... | 2009 | 19776164 |
| horizontal gene transfer and recombination shape mesorhizobial populations in the gene center of the host plants astragalus luteolus and astragalus ernestii in sichuan, china. | thirty-three rhizobial strains isolated from the root nodules of astragalus luteolus and astragalus ernestii growing on the west plateau at two different altitudes in sichuan province, china, were characterized by amplified rdna restriction analysis (ardra), amplified fragment length polymorphism (aflp), and by sequencing of rrs, glna, glnii and nifh. the ardra analysis revealed considerable genomic diversity. in aflp analysis, 20 of 33 astragalus rhizobia formed three distinct clades, with othe ... | 2009 | 19796139 |
| chemoenzymatic synthesis of gdp-l-fucose and the lewis x glycan derivatives. | lewis x (le(x))-containing glycans play important roles in numerous cellular processes. however, the absence of robust, facile, and cost-effective methods for the synthesis of le(x) and its structurally related analogs has severely hampered the elucidation of the specific functions of these glycan epitopes. here we demonstrate that chemically defined guanidine 5'-diphosphate-beta-l-fucose (gdp-fucose), the universal fucosyl donor, the le(x) trisaccharide, and their c-5 substituted derivatives ca ... | 2009 | 19805264 |
| genetic analysis of ethylene regulation of legume nodulation. | the gaseous hormone ethylene has multiple roles in plant development and responses to external cues. among these is the regulation of "rhizobium"-induced nodulation in legumes. extensive descriptive literature exists, but has been expanded to allow more mechanistic analysis through the application of genetics. both mutants and transgenics displaying ethylene insensitivity have now been described, suggesting an intimate interplay of ethylene response, plant development and nodulation. | 2009 | 19847106 |
| structure of the o-polysaccharides of the lipopolysaccharides of mesorhizobium loti hambi 1148 and mesorhizobium amorphae atcc 19655 containing two o-methylated monosaccharides. | the o-polysaccharide of mesorhizobium loti hambi 1148 was obtained by mild acid degradation of the lipopolysaccharide and studied by sugar and methylation analyses, smith degradation, and (1)h and (13)c nmr spectroscopies, including 2d (1)h/(1)h cosy, tocsy, roesy, and h-detected (1)h/(13)c hsqc experiments. the o-polysaccharide was found to have a branched hexasaccharide-repeating unit of the following structure: [formula: see text] where 2-acetamido-2-deoxy-4-o-methyl-d-glucose (d-glcnac4me) a ... | 2009 | 19850286 |
| metabolic control of virulence genes in brucella abortus: hutc coordinates virb expression and the histidine utilization pathway by direct binding to both promoters. | type iv secretion systems (t4ss) are multicomponent machineries involved in the translocation of effector molecules across the bacterial cell envelope. the virb operon of brucella abortus codes for a t4ss that is essential for virulence and intracellular multiplication of the bacterium in the host. previous studies showed that the virb operon of b. abortus is tightly regulated within the host cells. in order to identify factors implicated in the control of virb expression, we searched for protei ... | 2010 | 19854911 |
| metabolic control of virulence genes in brucella abortus: hutc coordinates virb expression and the histidine utilization pathway by direct binding to both promoters. | type iv secretion systems (t4ss) are multicomponent machineries involved in the translocation of effector molecules across the bacterial cell envelope. the virb operon of brucella abortus codes for a t4ss that is essential for virulence and intracellular multiplication of the bacterium in the host. previous studies showed that the virb operon of b. abortus is tightly regulated within the host cells. in order to identify factors implicated in the control of virb expression, we searched for protei ... | 2010 | 19854911 |
| bradyrhizobia nodulating the acacia mangium x a. auriculiformis interspecific hybrid are specific and differ from those associated with both parental species. | in the context of an increasing utilization of the interspecific hybrid acacia mangium x a. auriculiformis as a plantation tree in the tropical humid zone, its symbiotic characterization was carried out in comparison with that of its two parental species. rhizobium strains of diverse geographical origins were isolated from root nodules of the hybrid and its parents. almost all acacia hybrid isolates were fast growing on yeast extract-mannitol medium, in contrast to those isolated from both paren ... | 2009 | 19854923 |
| topology of 4-pyridoxic acid dehydrogenase in transformed escherichia coli cells. | the topology of 4-pyridoxic acid dehydrogenase in the escherichia coli cell membrane was examined with transformed e. coli cells overexpressing the enzyme from mesorhizobium loti. the recombinant enzymes with a his(6)-tag either in the n-terminal region or at the c-terminus were localized on the e. coli cell membrane like the wild-type enzyme without a his(6)-tag. the his(6)-tags were labelled with ni-nta ap conjugate only when the e. coli protoplast cells were broken. the membrane-bound enzyme ... | 2010 | 19861399 |
| a type vi secretion system effector protein, vgrg1, from aeromonas hydrophila that induces host cell toxicity by adp ribosylation of actin. | we recently delineated the importance of a type vi secretion system (t6ss) gene cluster in the virulence of diarrheal isolate ssu of aeromonas hydrophila and showed that vash, a sigma(54) activator and t6ss component, was involved in the production of its associated effectors, e.g., hemolysin-coregulated protein. to identify additional t6ss effectors and/or secreted proteins, we subjected culture supernatants from deletion mutants of a. hydrophila, namely, a delta act mutant (a t2ss-associated c ... | 2010 | 19880608 |
| a type vi secretion system effector protein, vgrg1, from aeromonas hydrophila that induces host cell toxicity by adp ribosylation of actin. | we recently delineated the importance of a type vi secretion system (t6ss) gene cluster in the virulence of diarrheal isolate ssu of aeromonas hydrophila and showed that vash, a sigma(54) activator and t6ss component, was involved in the production of its associated effectors, e.g., hemolysin-coregulated protein. to identify additional t6ss effectors and/or secreted proteins, we subjected culture supernatants from deletion mutants of a. hydrophila, namely, a delta act mutant (a t2ss-associated c ... | 2010 | 19880608 |
| nodulation gene mutants of mesorhizobium loti r7a-nodz and noll mutants have host-specific phenotypes on lotus spp. | rhizobial nod factors induce plant responses and facilitate bacterial infection, leading to the development of nitrogen-fixing root nodules on host legumes. nodule initiation is highly dependent on nod-factor structure and, hence, on at least some of the nodulation genes that encode nod-factor production. here, we report the effects of mutations in mesorhizobium loti r7a nodulation genes on nodulation of four lotus spp. and on nod-factor structure. most mutants, including a deltanodsdeltanolo do ... | 2009 | 19888820 |
| analysis of lipid export in hydrocarbonoclastic bacteria of the genus alcanivorax: identification of lipid export-negative mutants of alcanivorax borkumensis sk2 and alcanivorax jadensis t9. | triacylglycerols (tags), wax esters (wes), and polyhydroxyalkanoates (phas) are the major hydrophobic compounds synthesized in bacteria and deposited as cytoplasmic inclusion bodies when cells are cultivated under imbalanced growth conditions. the intracellular occurrence of these compounds causes high costs for downstream processing. alcanivorax species are able to produce extracellular lipids when the cells are cultivated on hexadecane or pyruvate as the sole carbon source. in this study, we d ... | 2010 | 19933359 |
| analysis of lipid export in hydrocarbonoclastic bacteria of the genus alcanivorax: identification of lipid export-negative mutants of alcanivorax borkumensis sk2 and alcanivorax jadensis t9. | triacylglycerols (tags), wax esters (wes), and polyhydroxyalkanoates (phas) are the major hydrophobic compounds synthesized in bacteria and deposited as cytoplasmic inclusion bodies when cells are cultivated under imbalanced growth conditions. the intracellular occurrence of these compounds causes high costs for downstream processing. alcanivorax species are able to produce extracellular lipids when the cells are cultivated on hexadecane or pyruvate as the sole carbon source. in this study, we d ... | 2010 | 19933359 |
| host plant genome overcomes the lack of a bacterial gene for symbiotic nitrogen fixation. | homocitrate is a component of the iron-molybdenum cofactor in nitrogenase, where nitrogen fixation occurs. nifv, which encodes homocitrate synthase (hcs), has been identified from various diazotrophs but is not present in most rhizobial species that perform efficient nitrogen fixation only in symbiotic association with legumes. here we show that the fen1 gene of a model legume, lotus japonicus, overcomes the lack of nifv in rhizobia for symbiotic nitrogen fixation. a fix(-) (non-fixing) plant mu ... | 2009 | 19940927 |
| novel tn4371-ice like element in ralstonia pickettii and genome mining for comparative elements. | integrative conjugative elements (ices) are important factors in the plasticity of microbial genomes. an element related to the ice tn4371 was discovered during a bioinformatic search of the ralstonia pickettii 12j genome. this element was analysed and further searches carried out for additional elements.a pcr method was designed to detect and characterise new elements of this type based on this scaffold and a culture collection of fifty-eight ralstonia pickettii and ralstonia insidiosa strains ... | 2009 | 19941653 |
| autonomous plasmid-like replication of a conjugative transposon. | integrative and conjugative elements (ices), a.k.a. conjugative transposons, are mobile genetic elements involved in many biological processes, including pathogenesis, symbiosis and the spread of antibiotic resistance. unlike conjugative plasmids that are extra-chromosomal and replicate autonomously, ices are integrated in the chromosome and replicate passively during chromosomal replication. it is generally thought that ices do not replicate autonomously. we found that when induced, bacillus su ... | 2010 | 19943900 |
| autonomous plasmid-like replication of a conjugative transposon. | integrative and conjugative elements (ices), a.k.a. conjugative transposons, are mobile genetic elements involved in many biological processes, including pathogenesis, symbiosis and the spread of antibiotic resistance. unlike conjugative plasmids that are extra-chromosomal and replicate autonomously, ices are integrated in the chromosome and replicate passively during chromosomal replication. it is generally thought that ices do not replicate autonomously. we found that when induced, bacillus su ... | 2010 | 19943900 |
| identification of the mesorhizobium loti gene responsible for glycerophosphorylation of periplasmic cyclic beta-1,2-glucans. | periplasmic cyclic beta-1,2-glucans play a crucial role in symbiosis as well as in hypo-osmotic adaptation for rhizobia. these glucans are modified in many species by anionic substituents such as glycerophosphoryl and succinyl ones, but their role remains to be examined. in this work, the cgma homolog is shown to be responsible for glycerophosphorylation of cyclic beta-1,2-glucans in mesorhizobium loti. the mutation in cgma converted most anionic glucans into neutral ones, leaving a small amount ... | 2010 | 19951365 |
| improved characterization of nod factors and genetically based variation in lysm receptor domains identify amino acids expendable for nod factor recognition in lotus spp. | formation of functional nodules is a complex process depending on host-microsymbiont compatibility in all developmental stages. this report uses the contrasting symbiotic phenotypes of lotus japonicus and l. pedunculatus, inoculated with mesorhizobium loti or the bradyrhizobium sp. (lotus), to investigate the role of nod factor structure and nod factor receptors (nfr) for rhizobial recognition, infection thread progression, and bacterial persistence within nodule cells. a key contribution was th ... | 2010 | 19958139 |
| 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 |
| salicylic acid differentially affects suspension cell cultures of lotus japonicus and one of its non-symbiotic mutants. | salicylic acid (sa) is known to play an important role in the interaction between plant and micro-organisms, both symbiotic and pathogen. in particular, high levels of sa block nodule formation and mycorrhizal colonization in plants. a mutant of lotus japonicus, named ljsym4-2, was characterized as unable to establish positive interactions with rhizobium and fungi (nod(-), myc(-)); in particular, it does not recognize signal molecules released by symbiotic micro-organisms so that eventually, epi ... | 2010 | 20012170 |
| sinorhizobium meliloti phospholipase c required for lipid remodeling during phosphorus limitation. | rhizobia are gram-negative soil bacteria able to establish nitrogen-fixing root nodules with their respective legume host plants. besides phosphatidylglycerol, cardiolipin, and phosphatidylethanolamine, rhizobial membranes contain phosphatidylcholine (pc) as a major membrane lipid. under phosphate-limiting conditions of growth, some bacteria replace their membrane phospholipids with lipids lacking phosphorus. in sinorhizobium meliloti, these phosphorus-free lipids are sulfoquinovosyl diacylglyce ... | 2010 | 20018679 |
| sinorhizobium meliloti phospholipase c required for lipid remodeling during phosphorus limitation. | rhizobia are gram-negative soil bacteria able to establish nitrogen-fixing root nodules with their respective legume host plants. besides phosphatidylglycerol, cardiolipin, and phosphatidylethanolamine, rhizobial membranes contain phosphatidylcholine (pc) as a major membrane lipid. under phosphate-limiting conditions of growth, some bacteria replace their membrane phospholipids with lipids lacking phosphorus. in sinorhizobium meliloti, these phosphorus-free lipids are sulfoquinovosyl diacylglyce ... | 2010 | 20018679 |
| nmr assignments of the dna binding domain of ml4 protein from mesorhizobium loti. | ml4 protein from mesorhizobium loti has a 58% sequence identity with the ros protein from agrobacterium tumefaciens that contains a prokaryotic cys(2)his(2) zinc finger domain. interestingly, ml4 is a zinc-lacking protein that does not contain the cys(2)his(2) motif and is able to bind the ros dna target sequence with high affinity. here we report the (1)h, (15)n and (13)c nmr assignments of the ml4 protein dna binding domain (residue 52-151), as an important step toward elucidating at a molecul ... | 2010 | 20020226 |
| rhizobium leguminosarum hupe encodes a nickel transporter required for hydrogenase activity. | synthesis of the hydrogen uptake (hup) system in rhizobium leguminosarum bv. viciae requires the function of an 18-gene cluster (hupslcdefghijk-hypabfcdex). among them, the hupe gene encodes a protein showing six transmembrane domains for which a potential role as a nickel permease has been proposed. in this paper, we further characterize the nickel transport capacity of hupe and that of the translated product of hupe2, a hydrogenase-unlinked gene identified in the r. leguminosarum genome. hupe2 ... | 2010 | 20023036 |
| rhizobium leguminosarum hupe encodes a nickel transporter required for hydrogenase activity. | synthesis of the hydrogen uptake (hup) system in rhizobium leguminosarum bv. viciae requires the function of an 18-gene cluster (hupslcdefghijk-hypabfcdex). among them, the hupe gene encodes a protein showing six transmembrane domains for which a potential role as a nickel permease has been proposed. in this paper, we further characterize the nickel transport capacity of hupe and that of the translated product of hupe2, a hydrogenase-unlinked gene identified in the r. leguminosarum genome. hupe2 ... | 2010 | 20023036 |
| functional role of bradyrhizobium japonicum trehalose biosynthesis and metabolism genes during physiological stress and nodulation. | trehalose, a disaccharide accumulated by many microorganisms, acts as a protectant during periods of physiological stress, such as salinity and desiccation. previous studies reported that the trehalose biosynthetic genes (otsa, tres, and trey) in bradyrhizobium japonicum were induced by salinity and desiccation stresses. functional mutational analyses indicated that disruption of otsa decreased trehalose accumulation in cells and that an otsa trey double mutant accumulated an extremely low level ... | 2010 | 20023090 |
| functional role of bradyrhizobium japonicum trehalose biosynthesis and metabolism genes during physiological stress and nodulation. | trehalose, a disaccharide accumulated by many microorganisms, acts as a protectant during periods of physiological stress, such as salinity and desiccation. previous studies reported that the trehalose biosynthetic genes (otsa, tres, and trey) in bradyrhizobium japonicum were induced by salinity and desiccation stresses. functional mutational analyses indicated that disruption of otsa decreased trehalose accumulation in cells and that an otsa trey double mutant accumulated an extremely low level ... | 2010 | 20023090 |
| conserved symbiotic plasmid dna sequences in the multireplicon pangenomic structure of rhizobium etli. | strains of the same bacterial species often show considerable genomic variation. to examine the extent of such variation in rhizobium etli, the complete genome sequence of r. etli ciat652 and the partial genomic sequences of six additional r. etli strains having different geographical origins were determined. the sequences were compared with each other and with the previously reported genome sequence of r. etli cfn42. dna sequences common to all strains constituted the greater part of these geno ... | 2010 | 20048063 |
| structural determinants of substrate recognition in the had superfamily member d-glycero-d-manno-heptose-1,7-bisphosphate phosphatase (gmhb) . | the haloalkanoic acid dehalogenase (had) enzyme superfamily is the largest family of phosphohydrolases. in had members, the structural elements that provide the binding interactions that support substrate specificity are separated from those that orchestrate catalysis. for most had phosphatases, a cap domain functions in substrate recognition. however, for the had phosphatases that lack a cap domain, an alternate strategy for substrate selection must be operative. one such had phosphatase, gmhb ... | 2010 | 20050614 |
| divergence of biochemical function in the had superfamily: d-glycero-d-manno-heptose-1,7-bisphosphate phosphatase (gmhb). | d-glycero-d-manno-heptose-1,7-bisphosphate phosphatase (gmhb) is a member of the histidinol-phosphate phosphatase (hisb) subfamily of the haloalkanoic acid dehalogenase (had) enzyme superfamily. gmhb supports two divergent biochemical pathways in bacteria: the d-glycero-d-manno-heptose-1alpha-gdp pathway (in s-layer glycoprotein biosynthesis) and the l-glycero-d-manno-heptose-1beta-adp pathway (in lipid a biosynthesis). herein, we report the comparative analysis of substrate recognition in selec ... | 2010 | 20050615 |
| global transcriptional analysis of nitrogen fixation and ammonium repression in root-associated pseudomonas stutzeri a1501. | biological nitrogen fixation is highly controlled at the transcriptional level by regulatory networks that respond to the availability of fixed nitrogen. in many diazotrophs, addition of excess ammonium in the growth medium results in immediate repression of nif gene transcription. although the regulatory cascades that control the transcription of the nif genes in proteobacteria have been well investigated, there are limited data on the kinetics of ammonium-dependent repression of nitrogen fixat ... | 2010 | 20053297 |
| fimr and fims: biofilm formation and gene expression in porphyromonas gingivalis. | porphyromonas gingivalis is a late-colonizing bacterium of the subgingival dental plaque biofilm associated with periodontitis. two p. gingivalis genes, fimr and fims, are predicted to encode a two-component signal transduction system comprising a response regulator (fimr) and a sensor histidine kinase (fims). in this study, we show that fims and fimr, although contiguous on the genome, are not part of an operon. we inactivated fimr and fims in both the afimbriated strain w50 and the fimbriated ... | 2010 | 20061484 |
| identification and functional analysis of type iii effector proteins in mesorhizobium loti. | mesorhizobium loti maff303099, a microsymbiont of the model legume lotus japonicus, possesses a cluster of genes (tts) that encode a type iii secretion system (t3ss). in the presence of heterologous nodd from rhizobium leguminosarum and a flavonoid naringenin, we observed elevated expression of the tts genes and secretion of several proteins into the culture medium. inoculation experiments with wild-type and t3ss mutant strains revealed that the presence of the t3ss affected nodulation at a spec ... | 2010 | 20064065 |
| the sinorhizobium meliloti rna chaperone hfq mediates symbiosis of s. meliloti and alfalfa. | there exist commonalities between symbiotic sinorhizobium meliloti and pathogenic brucella bacteria in terms of extensive gene synteny and the requirements for intracellular survival in their respective hosts. the rna chaperone hfq is essential for virulence for several bacterial groups, including brucella; however, its role in s. meliloti has not been investigated. our studies of an s. meliloti loss-of-function hfq mutant have revealed that hfq plays a key role in the establishment of the symbi ... | 2010 | 20081033 |
| genome-wide detection of predicted non-coding rnas in rhizobium etli expressed during free-living and host-associated growth using a high-resolution tiling array. | non-coding rnas (ncrnas) play a crucial role in the intricate regulation of bacterial gene expression, allowing bacteria to quickly adapt to changing environments. in the past few years, a growing number of regulatory rna elements have been predicted by computational methods, mostly in well-studied gamma-proteobacteria but lately in several alpha-proteobacteria as well. here, we have compared an extensive compilation of these non-coding rna predictions to intergenic expression data of a whole-ge ... | 2010 | 20089193 |
| the systemic imprint of growth and its uses in ecological (meta)genomics. | microbial minimal generation times range from a few minutes to several weeks. they are evolutionarily determined by variables such as environment stability, nutrient availability, and community diversity. selection for fast growth adaptively imprints genomes, resulting in gene amplification, adapted chromosomal organization, and biased codon usage. we found that these growth-related traits in 214 species of bacteria and archaea are highly correlated, suggesting they all result from growth optimi ... | 2010 | 20090831 |
| structure determination and characterization of the vitamin b6 degradative enzyme (e)-2-(acetamidomethylene)succinate hydrolase. | the gene identification and kinetic characterization of (e)-2-(acetamidomethylene)succinate (e-2ams) hydrolase has recently been described. this enzyme catalyzes the final reaction in the degradation of vitamin b(6) and produces succinic semialdehyde, acetate, ammonia, and carbon dioxide from e-2ams. the structure of e-2ams hydrolase was determined to 2.3 a using sad phasing. e-2ams hydrolase is a member of the alpha/beta hydrolase superfamily and utilizes a serine/histidine/aspartic acid cataly ... | 2010 | 20099871 |
| computational prediction of type iii secreted proteins from gram-negative bacteria. | type iii secretion system (t3ss) is a specialized protein delivery system in gram-negative bacteria that injects proteins (called effectors) directly into the eukaryotic host cytosol and facilitates bacterial infection. for many plant and animal pathogens, t3ss is indispensable for disease development. recently, t3ss has also been found in rhizobia and plays a crucial role in the nodulation process. although a great deal of efforts have been done to understand type iii secretion, the precise mec ... | 2010 | 20122221 |
| altered lipid a structures and polymyxin hypersensitivity of rhizobium etli mutants lacking the lpxe and lpxf phosphatases. | the lipid a of rhizobium etli, a nitrogen-fixing plant endosymbiont, displays significant structural differences when compared to that of escherichia coli. an especially striking feature of r. etli lipid a is that it lacks both the 1- and 4'-phosphate groups. the 4'-phosphate moiety of the distal glucosamine unit is replaced with a galacturonic acid residue. the dephosphorylated proximal unit is present as a mixture of the glucosamine hemiacetal and an oxidized 2-aminogluconate derivative. disti ... | 2010 | 20153447 |
| a new small regulatory protein, hmup, modulates haemin acquisition in sinorhizobium meliloti. | sinorhizobium meliloti has multiple systems for iron acquisition, including the use of haem as an iron source. haem internalization involves the shmr haem outer membrane receptor and the hmutuv locus, which participates in haem transport across the cytoplasmic membrane. previous studies have demonstrated that expression of the shmr gene is negatively regulated by iron through rira. here, we identify hmup in a genetic screen for mutants that displayed aberrant control of shmr. the normal inductio ... | 2010 | 20167620 |
| thiosulfate-dependent chemolithoautotrophic growth of bradyrhizobium japonicum. | thiosulfate-oxidizing sox gene homologues were found at four loci (i, ii, iii, and iv) on the genome of bradyrhizobium japonicum usda110, a symbiotic nitrogen-fixing bacterium in soil. in fact, b. japonicum usda110 can oxidize thiosulfate and grow under a chemolithotrophic condition. the deletion mutation of the soxy(1) gene at the sox locus i, homologous to the sulfur-oxidizing (sox) system in alphaproteobacteria, left b. japonicum unable to oxidize thiosulfate and grow under chemolithotrophic ... | 2010 | 20173070 |
| phylogenomics reveals a diverse rickettsiales type iv secretion system. | with an obligate intracellular lifestyle, alphaproteobacteria of the order rickettsiales have inextricably coevolved with their various eukaryotic hosts, resulting in small, reductive genomes and strict dependency on host resources. unsurprisingly, large portions of rickettsiales genomes encode proteins involved in transport and secretion. one particular transporter that has garnered recent attention from researchers is the type iv secretion system (t4ss). homologous to the well-studied archetyp ... | 2010 | 20176788 |
| synthesis of 4-diphosphocytidyl-2-c-methyl-d-erythritol 2-phosphate and kinetic studies of mycobacterium tuberculosis ispf. | many pathogenic bacteria utilize the 2-c-methyl-d-erythritol 4-phosphate (mep) pathway for the biosynthesis of isopentenyl diphosphate and dimethylallyl diphosphate, two major building blocks of isoprenoid compounds. the fifth enzyme in the mep pathway, 2-c-methyl-d-erythritol 2,4-cyclodiphosphate (me-cpp) synthase (ispf), catalyzes the conversion of 4-diphosphocytidyl-2-c-methyl-d-erythritol 2-phosphate (cdp-me2p) to me-cpp with a corresponding release of cytidine 5-monophosphate (cmp). because ... | 2010 | 20189102 |
| evolution and regulation of the lotus japonicus lysm receptor gene family. | lysm receptor kinases were identified as receptors of acylated chitin (nod factors) or chitin produced by plant-interacting microbes. here, we present the identification and characterization of the lysm receptor kinase gene (lys) family (17 members) in lotus japonicus. comprehensive phylogenetic analysis revealed a correlation between lys gene structure and phylogeny. further mapping coupled with sequence-based anchoring on the genome showed that the family has probably expanded by a combination ... | 2010 | 20192837 |
| the sinorhizobium meliloti rna chaperone hfq influences central carbon metabolism and the symbiotic interaction with alfalfa. | the bacterial hfq protein is able to interact with diverse rna molecules, including regulatory small non-coding rnas (srnas), and thus it is recognized as a global post-transcriptional regulator of gene expression. loss of hfq has an extensive impact in bacterial physiology which in several animal pathogens influences virulence. sinorhizobium meliloti is a model soil bacterium known for its ability to establish a beneficial nitrogen-fixing intracellular symbiosis with alfalfa. despite the predic ... | 2010 | 20205931 |
| heme-responsive dna binding by the global iron regulator irr from rhizobium leguminosarum. | heme, a physiologically crucial form of iron, is a cofactor for a very wide range of proteins and enzymes. these include dna regulatory proteins in which heme is a sensor to which an analyte molecule binds, effecting a change in the dna binding affinity of the regulator. given that heme, and more generally iron, must be carefully regulated, it is surprising that there are no examples yet in bacteria in which heme itself is sensed directly by a reversibly binding dna regulatory protein. here we s ... | 2010 | 20233710 |
| a metaproteomic analysis of the human salivary microbiota by three-dimensional peptide fractionation and tandem mass spectrometry. | metagenomics uses gene expression patterns to understand the taxonomy and metabolic activities of microbial communities. metaproteomics applies the same approach to community proteomes. previously, we used a novel three-dimensional peptide separation method to identify over 2000 salivary proteins. this study used those data to carry out the first metaproteomic analysis of the human salivary microbiota. the metagenomic software megan generated a phylogenetic tree, which was checked against the hu ... | 2010 | 20331792 |
| loss of the response regulator ctra causes pleiotropic effects on gene expression but does not affect growth phase regulation in rhodobacter capsulatus. | the purple nonsulfur photosynthetic bacterium rhodobacter capsulatus has been extensively studied for its metabolic versatility as well as for production of a gene transfer agent called rcgta. production of rcgta is highest in the stationary phase of growth and requires the response regulator protein ctra. the ctra protein in caulobacter crescentus has been thoroughly studied for its role as an essential, master regulator of the cell cycle. although the ctra protein in r. capsulatus shares a hig ... | 2010 | 20363938 |