Publications
| Title | Abstract | Year(sorted descending) Filter | PMID Filter |
|---|
| a three-dimensional model of myxobacterial fruiting-body formation. | myxobacterial cells are social; they swarm by gliding on surfaces as they feed cooperatively. when they sense starvation, tens of thousands of cells change their movement pattern from outward spreading to inward concentration and form aggregates that become fruiting bodies. cells inside fruiting bodies differentiate into round, nonmotile, environmentally resistant spores. traditionally, cell aggregation has been considered to imply chemotaxis, a long-range cell interaction that shares many featu ... | 2006 | 17088558 |
| dna replication during aggregation phase is essential for myxococcus xanthus development. | previous studies have demonstrated that fruiting body-derived myxococcus xanthus myxospores contain two fully replicated copies of its genome, implying developmental control of chromosome replication and septation. in this study, we employ dna replication inhibitors to determine if chromosome replication is essential to development and the exact time frame in which chromosome replication occurs within the developmental cycle. our results show that dna replication during the aggregation phase is ... | 2006 | 16585738 |
| four signalling domains in the hybrid histidine protein kinase rodk of myxococcus xanthus are required for activity. | in prokaryotes, the principal signal transduction systems operating at the level of protein phosphorylation are the two-component systems. a number of hybrid histidine protein kinases in these systems contain several receiver domains, however, the function of these receiver domains is unknown. the rodk kinase in myxococcus xanthus has an unconventional domain composition with a putative n-terminal sensor domain followed by a histidine kinase domain and three receiver domains. rodk is essential f ... | 2006 | 16573700 |
| the dif chemosensory pathway is directly involved in phosphatidylethanolamine sensory transduction in myxococcus xanthus. | myxococcus xanthus cells glide on solid surfaces and are chemotactically stimulated by certain phosphatidylethanolamine species. the dif gene cluster consists of six genes, difabcdeg, five of which encode proteins homologous to known chemotaxis proteins. difa and dife are required for the biosynthesis of fibrils, an extracellular matrix comprised of polysaccharide and protein. chemotactic stimulation by 1,2-o-bis[11-(z)-hexadecenoyl]-sn-glycero-3-phosphatidylethanolamine (16:1 pe) and dilauroyl ... | 2005 | 16102016 |
| fermentation, purification, formulation, and pharmacological evaluation of a prolyl endopeptidase from myxococcus xanthus: implications for celiac sprue therapy. | celiac sprue is a multi-factorial disease characterized by an inflammatory response to ingested wheat gluten and similar proteins in rye and barley. proline-rich gluten peptides from wheat, rye, and barley are relatively resistant to gastrointestinal digestion, and therefore persist in the intestinal lumen to elicit immunopathology in genetically susceptible individuals. in this study, we characterize the in vitro gluten detoxifying properties of a therapeutically promising prolyl endopeptidase ... | 2005 | 16136593 |
| exploring the diversity of myxobacteria in a soil niche by myxobacteria-specific primers and probes. | the diversity of myxobacteria in a soil niche was explored using culture-dependent and -independent methods. conventional cultivation for bacteriolytic myxobacteria produced six types of myxobacteria, which were identified as two myxococcus spp., two corallococcus spp., a cystobacter sp. and a nannocysts sp. hybridization analysis of the soil bacterial 16s rrna gene library with myxobacteria-specific probes revealed that myxobacteria accounted for less than 1% in the bacterial community. a cysto ... | 2005 | 16156733 |
| nitrate-dependent activation of the dif signaling pathway of myxococcus xanthus mediated by a narx-difa interspecies chimera. | myxococcus xanthus fibril exopolysaccharide (eps), essential for the social gliding motility and development of this bacterium, is regulated by the dif chemotaxis-like pathway. difa, an mcp homolog, is proposed to mediate signal input to the dif pathway. however, difa lacks a prominent periplasmic domain, which in classical chemoreceptors is responsible for signal perception and for initiating transmembrane signaling. to investigate the signaling properties of difa, we constructed a narx-difa (n ... | 2005 | 16159775 |
| rasa is required for myxococcus xanthus development and social motility. | an insertion in the rasa gene entirely blocked developmental aggregation and sporulation in myxococcus xanthus while also reducing swarm expansion on a 0.3% agar surface. data presented here demonstrate that rasa is required for extracellular fibril formation and social gliding motility. | 2005 | 16166548 |
| inorganic polyphosphate in the social life of myxococcus xanthus: motility, development, and predation. | inorganic polyphosphate (poly p), a polymer of tens or hundreds of phosphate residues linked by high-energy, atp-like bonds, is found in all organisms and performs a wide variety of functions. myxococcus xanthus, a social bacterium that feeds on other bacteria and forms fruiting bodies and spores, depends on poly p for motility, development, and nutritional predation. two poly p metabolizing enzymes were studied in m. xanthus: poly p kinase 1, which synthesizes poly p reversibly from atp, and po ... | 2005 | 16174737 |
| dna replication during sporulation in myxococcus xanthus fruiting bodies. | during the developmental process of the gram-negative soil bacterium myxococcus xanthus, vegetatively growing rod cells differentiate to ultimately become metabolically quiescent and environmentally resistant myxospores encased within fruiting bodies. this program, initiated by nutrient deprivation, is propagated by both cell-autonomous and cell-nonautonomous signals. our goal was to determine whether m. xanthus, like many other developmental systems, uses cell-cycle cues to regulate and control ... | 2005 | 16183740 |
| a novel bacterial signalling system with a combination of a ser/thr kinase cascade and a his/asp two-component system. | prokaryotes and eukaryotes have long been thought to use very different types of kinases (the his kinases of the 'bacterial' two-component systems versus the 'eukaryotic' ser/thr/tyr kinases) to carry out signal transduction. this paradigm no longer holds true, because both systems are now found together in an increasing number of prokaryotic organisms and 'two-component' his kinase are present in eukaryotes. pioneering work on bacterial protein serine threonine kinases (pstks) has been performe ... | 2005 | 16194223 |
| identification of a protein ser/thr kinase cascade that regulates essential transcriptional activators in myxococcus xanthus development. | pkn8 is a membrane-associated protein ser/thr kinase (pstk) of myxoccocus xanthus that was previously found to associate with a novel cytoplasmic kinase, pkn14. in the present study, mrpc, an essential transcription factor for frua expression during fruiting body development, was identified using a genomic yeast two-hybrid screen with pkn14 as bait. our biochemical studies demonstrated that purified pkn8 and pkn14 are active kinases and that pkn8 is able to phosphorylate pkn14 that forms a tetra ... | 2005 | 16194226 |
| [monitoring of microbial degraders in manned space stations]. | samples of microorganisms from the surface of constructions of mir space station (mir ss) were taken and examined after 13 years of operation. the following microorganisms were isolated and identified: 12 fungal species belonging to the genera penicillium, aspergillus, cladosporium, and aureobasidium; 3 yeast species belonging to the genera debaryomyces, candida, and rhodotorula; and 4 bacterial species belonging to the genera bacillus, myxococcus, and rhodococcus. the predominant species in all ... | 2005 | 16212041 |
| exopolysaccharide biosynthesis genes required for social motility in myxococcus xanthus. | social (s)-motility in myxococcus xanthus is a flagellum-independent gliding motility system that allows bacteria to move in groups on solid surfaces. s-motility has been shown to require type iv pili (tfp), exopolysaccharide (eps; a component of fibrils) and lipopolysaccharide (lps). previously, information concerning eps biogenesis in m. xanthus was lacking. in this study, we screened 5000 randomly mutagenized colonies for defects in s-motility and eps and identified two genetic regions essent ... | 2005 | 15612929 |
| biosynthesis of iso-fatty acids in myxobacteria: iso-even fatty acids are derived by alpha-oxidation from iso-odd fatty acids. | the biosynthesis of iso-fatty acids was investigated in the myxobacteria myxococcus xanthus and stigmatella aurantiaca by feeding labeled precursors of these fatty acids and by conducting detailed analysis of the fatty acid profiles and fatty acid ms and nmr spectra. these experiments revealed that in s. aurantiaca all iso-even fatty acids are formed via alpha-oxidation of iso-odd fatty acids and not by using valine-derived isobutyryl-coa. | 2005 | 15643871 |
| enhancer-binding proteins with a forkhead-associated domain and the sigma54 regulon in myxococcus xanthus fruiting body development. | in response to starvation, myxococcus xanthus initiates a developmental program that results in the formation of spore-filled, multicellular fruiting bodies. many developmentally regulated genes in m. xanthus are transcribed from sigma(54) promoters, and these genes require enhancer-binding proteins. here we report the finding of an unusual group of 12 genes encoding sigma(54)-dependent enhancer-binding proteins containing a forkhead-associated (fha) domain as their n-terminal sensory domain. fh ... | 2005 | 15668379 |
| analysis of type iv pilus and its associated motility in myxococcus xanthus using an antibody reactive with native pilin and pili. | myxococcus xanthus possesses a social gliding motility that requires type iv pili (tfp). according to the current model, m. xanthus pili attach to an external substrate and retract, pulling the cell body forward along their long axis. by analogy with the situation in other bacteria employing tfp-dependent motility, m. xanthus pili have been assumed to be composed of pilin (pila) subunits, but this has not previously been confirmed. the first 28 amino acids of the m. xanthus pila protein share ex ... | 2005 | 15699186 |
| eukaryotic-like signaling and gene regulation in a prokaryote that undergoes multicellular development. | 2005 | 15710872 | |
| characterization of developmental autolysis in myxobacterial fruiting body morphogenesis with profiling of amino acids using capillary electrophoresis method. | capillary electrophoresis equipped with laser-induced fluorescence (ce-lif), combining with micro-culture technique was employed to determine extracellular amino acids in single myxobacterial fruiting body morphogenesis. the result showed that in the early aggregation stage, there was a remarkable increase of extracellular amino acids, which was produced by developmentally induced autolysis. the amino acids were then consumed by the vegetative cells in aggregation stage. in the following develop ... | 2005 | 15711868 |
| divergent regulatory pathways control a and s motility in myxococcus xanthus through frze, a chea-chey fusion protein. | myxococcus xanthus moves on solid surfaces by using two gliding motility systems, a motility for individual-cell movement and s motility for coordinated group movements. the frz genes encode chemotaxis homologues that control the cellular reversal frequency of both motility systems. one of the components of the core frz signal transduction pathway, frze, is homologous to both chea and chey from the enteric bacteria and is therefore a novel chea-chey fusion protein. in this study, we investigated ... | 2005 | 15716443 |
| grouping myxococci (corallococcus) strains by matrix-assisted laser desorption ionization time-of-flight (maldi tof) mass spectrometry: comparison with gene sequence phylogenies. | nine corallococcus isolates and three type strains of corallococcus species were characterized by intact cell mass spectrometry using matrix assisted laser desorption ionization time-of-flight (maldi-tof) mass spectrometry. the resulting phenetic clustering was compared to the phylogenetic grouping based upon sequences of two housekeeping genes. the three dendrograms of relatedness resembled each other in that the isolates were highly similar to the type strains of corallococcus exiguus and cora ... | 2005 | 15717228 |
| a myxococcus xanthus cbpb containing two camp-binding domains is involved in temperature and osmotic tolerances. | our previous data indicated that a myxococcus xanthus sensor-type adenylyl cyclase (cyaa) functions in signal transduction during osmotic stress. however, the camp-mediated signal transduction pathway in this bacterium was unknown. here, we isolated a clone from a m. xanthus genomic dna library using oligonucleotide probes designed based on the conserved camp-binding domains of the camp-dependent protein kinase (pka) regulatory subunits. the clone contained two open-reading frames (orfs), cbpa a ... | 2005 | 15727824 |
| structural and mechanistic analysis of two prolyl endopeptidases: role of interdomain dynamics in catalysis and specificity. | prolyl endopeptidases (peps) are a unique class of serine proteases with considerable therapeutic potential for the treatment of celiac sprue. the crystal structures of two didomain peps have been solved in alternative configurations, thereby providing insights into the mode of action of these enzymes. the structure of the sphingomonas capsulata pep, solved and refined to 1.8-a resolution, revealed an open configuration of the active site. in contrast, the inhibitor-bound pep from myxococcus xan ... | 2005 | 15738423 |
| regulating pilin expression reveals a threshold for s motility in myxococcus xanthus. | an isopropyl-beta-d-thiogalactopyranoside (iptg)-inducible promoter was constructed in myxococcus xanthus. the single-copy pila gene encodes pilin, the monomer unit of m. xanthus type iv pili. to vary the level of pila expression, we cloned its promoter in front of the lac operator, and a plasmid containing the construct was inserted into the chromosome of a deltapila strain. induction of pilin expression increased smoothly as the dose of iptg added to the culture was increased. iptg-induced pil ... | 2005 | 15743959 |
| demonstration of interactions among myxococcus xanthus dif chemotaxis-like proteins by the yeast two-hybrid system. | the myxococcus xanthus dif locus encodes several bacterial chemotaxis homologues that are crucial for fibril exopolysaccharide (eps) production, social gliding motility, and fruiting body development. in primary sequence, difa is homologous to methyl-accepting chemotaxis protein, difc to chew, difd to chey, dife to chea, and difg to chec. in this study, the interactions among the dif chemotaxis-like proteins were investigated using the yeast two-hybrid (y2h) system. difc was found to interact wi ... | 2005 | 15770502 |
| an individual based model of rippling movement in a myxobacteria population. | migrating cells of myxococcus xanthus (mx) in the early stages of starvation-induced development exhibit elaborate patterns of propagating waves. these so-called rippling patterns are formed by two sets of waves travelling in opposite directions. it has been experimentally shown that formation of these waves is mediated by cell-cell contact signalling (c-signalling). here, we develop an individual-based model to study the formation of rippling patterns in mx populations. following the work of ig ... | 2005 | 15784269 |
| bioinformatics, genomics and evolution of non-flagellar type-iii secretion systems: a darwinian perspective. | we review the biology of non-flagellar type-iii secretion systems from a darwinian perspective, highlighting the themes of evolution, conservation, variation and decay. the presence of these systems in environmental organisms such as myxococcus, desulfovibrio and verrucomicrobium hints at roles beyond virulence. we review newly discovered sequence homologies (e.g., yopn/tyea and sepl). we discuss synapomorphies that might be useful in formulating a taxonomy of type-iii secretion. the problem of ... | 2005 | 15808742 |
| nanoscale visualization and characterization of myxococcus xanthus cells with atomic force microscopy. | multicellular microbial communities are the predominant form of existence for microorganisms in nature. as one of the most primitive social organisms, myxococcus xanthus has been an ideal model bacterium for studying intercellular interaction and multicellular organization. through previous genetic and em studies, various extracellular appendages and matrix components have been found to be involved in the social behavior of m. xanthus, but none of them was directly visualized and analyzed under ... | 2005 | 15840722 |
| an adenylyl cyclase, cyab, acts as an osmosensor in myxococcus xanthus. | we have previously reported that a receptor-type adenylyl cyclase (cyaa) of myxococcus xanthus undergoes an osmosensor mainly during spore germination (y. kimura et al., j. bacteriol. 184:3578-3585, 2002). in the present study, we cloned another receptor-type adenylyl cyclase gene (cyab) and characterized the function of the cyab-encoded protein. disruption of cyab generates a mutant that showed growth retardation at high ionic (nacl) or high nonionic (sucrose) osmolarity. when vegetative cells ... | 2005 | 15866951 |
| analysing protein-protein interactions of the myxococcus xanthus dif signalling pathway using the yeast two-hybrid system. | the dif operon is essential for fruiting body formation, fibril (exopolysaccharide) production and social motility of myxococcus xanthus. the dif locus contains a gene cluster homologous to chemotaxis genes such as mcp (difa), chew (difc), chey (difd), chea (dife) and chec (diff), as well as an unknown orf called difb. this study used yeast two-hybrid analysis to investigate possible interactions between dif proteins, and determined that difa, c, d and e interact in a similar fashion to chemotax ... | 2005 | 15870463 |
| copper induction of carotenoid synthesis in the bacterium myxococcus xanthus. | copper induces a red pigmentation in cells of the bacterium myxococcus xanthus when they are incubated in the dark, at suboptimal growth conditions. the colouration results from the accumulation of carotenoids, as demonstrated by chemical analysis, and by the lack of a copper effect on m. xanthus mutants affected in known structural genes for carotenoid synthesis. none of several other metals or oxidative agents can mimic the copper effect on carotenoid synthesis. until now, blue light was the o ... | 2005 | 15882411 |
| modulating factors for the pkn4 kinase cascade in regulating 6-phosphofructokinase in myxococcus xanthus. | myxococcus xanthus, a gram-negative developmental bacterium, contains a large number of protein ser/thr kinases (pstks). among these pstks, pkn4 has been shown to be 6-phosphofructokinase (pfk) kinase. pfk associates with the regulatory domain of pkn4 (pkn4rd) and is activated by pkn4-mediated phosphorylation. the activation of pfk is required to consume glycogen accumulated during early development and is essential for efficient sporulation. using the yeast two-hybrid screen, we identified thre ... | 2005 | 15882423 |
| coupling of multicellular morphogenesis and cellular differentiation by an unusual hybrid histidine protein kinase in myxococcus xanthus. | we describe an unusual hybrid histidine protein kinase, which is important for spatially coupling cell aggregation and sporulation during fruiting body formation in myxococcus xanthus. a rodk mutant makes abnormal fruiting bodies and spores develop outside the fruiting bodies. rodk is a soluble, cytoplasmic protein, which contains an n-terminal sensor domain, a histidine protein kinase domain and three receiver domains. in vitro phosphorylation assays showed that rodk possesses kinase activity. ... | 2005 | 15882426 |
| herbicidal and antioxidant responses of transgenic rice overexpressing myxococcus xanthus protoporphyrinogen oxidase. | we analyzed the herbicidal and antioxidant defense responses of transgenic rice plants that overexpressed the myxococcus xanthus protoporphyrinogen oxidase gene. leaf squares of the wild-type incubated with oxyfluorfen were characterized by necrotic leaf lesions and increases in conductivity and malonyldialdehyde levels, whereas transgenic lines m4 and m7 did not show any change with up to 100 microm oxyfluorfen. the wild-type had decreased f(v)/f(m) and produced a high level of h(2)o(2) at 18 h ... | 2005 | 15890521 |
| generation of new epothilones by genetic engineering of a polyketide synthase in myxococcus xanthus. | epothilones, potent cytotoxic agents and potential anticancer drugs, are complex polyketides produced by a modular polyketide synthase (pks). the epothilone pks genes were introduced and expressed in myxococcus xanthus and engineered to generate novel unnatural natural products which can be used as new scaffolds for chemical modification. inactivation of the kr domain in module 6 of the epo pks resulted in accumulation of 9-oxoepothilone d and its isomer 8-epi-9-oxoepothilone d as the major prod ... | 2005 | 15895525 |
| force and flexibility of flailing myxobacteria. | myxococcus xanthus is a common gram-negative bacterium that moves by a process called gliding motility. in myxobacteria, two distinct mechanisms for gliding have been discovered. s-type motility requires the extension, attachment, and retraction of type iv pili. the other mechanism, designated as a-type motility, may be driven by the secretion and swelling of slime; however, experiments to confirm or refute this model are still lacking and the force exerted by this mechanism has not been measure ... | 2005 | 15908584 |
| characteristics and living patterns of marine myxobacterial isolates. | the growth, morphology, and life cycle of two marine myxobacterial isolates, halotolerant myxococcus fulvus strain hw-1 and halophilic haliangium ochraceum strain smp-2, were studied as models to determine the living patterns of myxobacteria in the ocean. the growth, morphology, and development of halotolerant strain hw-1 shifted in response to salinity. the optimal seawater concentration for growth of hw-1 was 0 to 80% (salinity, 0.1 to 2.9%), and the strain grew poorly in media with a salinity ... | 2005 | 15933036 |
| genomic dna amplification from a single bacterium. | genomic dna was amplified about 5 billion-fold from single, flow-sorted bacterial cells by the multiple displacement amplification (mda) reaction, using phi 29 dna polymerase. a 662-bp segment of the 16s rrna gene could be accurately sequenced from the amplified dna. mda methods enable new strategies for studying non-culturable microorganisms. | 2005 | 15933038 |
| making waves: pattern formation by a cell-surface-associated signal. | starving myxococcus xanthus cells organize into two strikingly different spatio-temporal patterns, either rippling or aggregation of cells into fruiting bodies. formation of both patterns depends on a cell-surface-associated, non-diffusible signal, the c-signal. a key motility parameter modulated by the c-signal during pattern formation is the frequency at which cells reverse their gliding direction, with low and high levels of c-signalling causing an increase and a decrease in the reversal freq ... | 2005 | 15936654 |
| identification of the omega4406 regulatory region, a developmental promoter of myxococcus xanthus, and a dna segment responsible for chromosomal position-dependent inhibition of gene expression. | when starved, myxococcus xanthus cells send signals to each other that coordinate their movements, gene expression, and differentiation. c-signaling requires cell-cell contact, and increasing contact brought about by cell alignment in aggregates is thought to increase c-signaling, which induces expression of many genes, causing rod-shaped cells to differentiate into spherical spores. c-signaling involves the product of the csga gene. a csga mutant fails to express many genes that are normally in ... | 2005 | 15937177 |
| functional genome annotation through phylogenomic mapping. | accurate determination of functional interactions among proteins at the genome level remains a challenge for genomic research. here we introduce a genome-scale approach to functional protein annotation--phylogenomic mapping--that requires only sequence data, can be applied equally well to both finished and unfinished genomes, and can be extended beyond single genomes to annotate multiple genomes simultaneously. we have developed and applied it to more than 200 sequenced bacterial genomes. protei ... | 2005 | 15940241 |
| mutations affecting predation ability of the soil bacterium myxococcus xanthus. | myxococcus xanthus genetic mutants with characterized phenotypes were analysed for the ability to prey on susceptible bacteria. quantification of predatory ability was scored by a newly developed method under conditions in which prey bacteria provided the only source of nutrients. these results were corroborated by data derived using a previously published protocol that measures predation in the presence of limited external nutrients. first, early developmental regulatory mutants were examined, ... | 2005 | 15941994 |
| gene sequence heterogeneity of corallococcus coralloides strains isolated from geographically diverse locations. | thirty-three strains classified as corallococcus coralloides isolated from mostly soil samples in 14 countries of four continents, were subjected to phylogenetic analyses. based on 16s rdna analyses the strains form a highly related cluster, sharing above 98.7% sequence similarity. four groups were recognized within this cluster, only one of which, containing two strains from st. lucia, lower antilles, was exclusively defined by strains from the same sample. the other groups contained members fr ... | 2005 | 15946298 |
| a novel type of geosmin biosynthesis in myxobacteria. | the biosynthesis of geosmin (1) and (1(10)e,5e)-germacradien-11-ol (2), two volatile terpenoid compounds emitted by the myxobacteria myxococcus xanthus and stigmatella aurantiaca, was investigated in feeding experiments with different labeled precursors. in these experiments, the volatiles released by the cell cultures grown on agar plates were collected with a closed-loop stripping apparatus (clsa) and analyzed by gc-ms. [(2)h(10)]leucine and [4,4,4,5,5,5-(2)h(6)]dimethylacrylate were fed to wi ... | 2005 | 15960521 |
| sense and sensibility in bacteria. viiith international conference on bacterial locomotion and sensory transduction. | 2005 | 15976817 | |
| cell-to-cell transfer of bacterial outer membrane lipoproteins. | myxococcus xanthus cells can glide forward by retracting type iv pili. tgl, an outer membrane lipoprotein, is necessary to assemble pili. tgl mutants can be transiently "stimulated" if brought into end-to-end contact with tgl+ donor cells. by separating the stimulated recipient cells from donor cells, we found that tgl protein was transferred from the donors to the rescued recipient cells. mutants lacking cglb lipoprotein, which is part of a second gliding engine, could also be stimulated, and c ... | 2005 | 15994555 |
| phor1-phop1, a third two-component system of the family phorp from myxococcus xanthus: role in development. | the pair phor1-phop1 is the third two-component system of the family phorp reported in m. xanthus. phor1 is a histidine kinase anchored to the membrane through a transmembrane domain located in the amino-terminal portion of the protein. as a result, 93% of the protein is located in the cytoplasm. this topology is unusual in the phor-type histidine kinases. phop1 is a response regulator with a helix-loop-helix motif typical of the dna-binding proteins. although the operon phopr1 is expressed duri ... | 2005 | 15995213 |
| espc is involved in controlling the timing of development in myxococcus xanthus. | the espc null mutation caused accelerated aggregation and formation of tiny fruiting bodies surrounded by spores, which were also observed in the espa mutant and in csga-overproducing cells in myxococcus xanthus. in addition, the espc mutant appeared to produce larger amounts of the complementary c-signal than the wild-type strain. these findings suggest that espc is involved in controlling the timing of fruiting body development in m. xanthus. | 2005 | 15995222 |
| characterization of a small heat shock protein, mx hsp16.6, of myxococcus xanthus. | a number of heat shock proteins in myxococcus xanthus were previously identified by two-dimensional (2d) gel electrophoresis. one of these protein was termed mx hsp16.6, and the gene encoding mx hsp16.6 was isolated. mx hsp16.6 consists of 147 amino acid residues and has an estimated molecular weight of 16,642, in accordance with the apparent molecular mass in the 2d gel. an alpha-crystallin domain, typically conserved in small heat shock proteins, was found in mx hsp16.6. mx hsp16.6 was not det ... | 2005 | 16030217 |
| biosynthesis of iso-fatty acids in myxobacteria. | the fatty acid (fa) profiles of the myxobacteria stigmatella aurantiaca and myxococcus xanthus were investigated by acidic methanolysis of total cell extracts and gc or gc-ms analysis. the main components were 13-methyltetradecanoic acid (iso-15:0) and (z)-hexadec-11-enoic acid (16:1, omega-5 cis). the biosynthesis of iso-fas was investigated in several feeding experiments. feeding of isovaleric acid (iva) to a mutant impaired in the degradation of leucine to isovaleryl-coa (iv-coa)(bkd mutant) ... | 2005 | 16032360 |
| a continuous fluorimetric assay for protoporphyrinogen oxidase by monitoring porphyrin accumulation. | a continuous spectrofluorimetric assay for protoporphyrinogen oxidase (ppo, ec 1.3.3.4) activity has been developed using a 96-well plate reader. protoporphyrinogen ix, the tetrapyrrole substrate, is a colorless nonfluorescent compound. the evolution of the fluorescent tetrapyrrole product, protoporphyrin ix, was detected using a fluorescence plate reader. the apparent km (kapp) values for protoporphyrinogen ix were measured as 3.8+/-0.3, 3.6+/-0.5, and 1.0+/-0.1 microm for the enzymes from huma ... | 2005 | 16039600 |
| identification of a gene involved in polysaccharide export as a transcription target of frua, an essential factor for myxococcus xanthus development. | fruiting body development in myxococcus xanthus is a multicellular event that is coordinated by exchanging intercellular signals. frua is a transcription factor essential for fruiting body development and is thought to play a key role in the c-signal pathway. here we present the first identification of a gene regulated by frua. the gene was isolated from a genomic library via in vitro selection in a dna binding assay by using the dna-binding domain of frua tagged with his(8) at the c-terminal en ... | 2005 | 16040607 |
| brge is a regulator of myxococcus xanthus development. | we report here the identification and characterization of a member of the myxococcus xanthus sdek signal transduction pathway, brge. this protein was identified as an sdek-interacting component using a yeast two-hybrid screen, and we further confirmed this interaction by the glutathione s-transferase (gst) pulldown assay. additional yeast two-hybrid analyses revealed that brge preferentially interacts with the putative amino-terminal sensor domain of sdek, but not with the carboxy-terminal kinas ... | 2005 | 16045620 |
| resource level affects relative performance of the two motility systems of myxococcus xanthus. | the adventurous (a) and social (s) motility systems of the microbial predator myxococcus xanthus show differential swarming performance on distinct surface types. under standard laboratory conditions, a-motility performs well on hard agar but poorly on soft agar, whereas the inverse pattern is shown by s-motility. these properties may allow m. xanthus to swarm effectively across a greater diversity of natural surfaces than would be possible with one motility system alone. nonetheless, the range ... | 2005 | 16052373 |
| a three-dimensional model of myxobacterial aggregation by contact-mediated interactions. | myxobacteria provide one of the simplest models of cell-cell interaction and organized cell movement leading to cellular differentiation. when starved, tens of thousands of cells change their movement pattern from outward spreading to inward concentration; they form aggregates that become fruiting bodies. cells inside fruiting bodies differentiate into round, nonmotile, environmentally resistant spores. traditionally, cell aggregation has been considered to imply chemotaxis; a long-range cell in ... | 2005 | 16061806 |
| assessment of fed-batch, semicontinuous, and continuous epothilone d production processes. | epothilone d is a member of a class of potent antineoplastic natural products produced by myxobacteria. previously, we have described a fed-batch epothilone d production process in which an adsorber resin is incorporated into the bioreactor setup to capture and stabilize the product in situ, preventing its degradation within the bioreactor. the capture of epothilone d by these relatively large resin beads enables the development of continuous and semicontinuous culturing systems incorporating be ... | 2005 | 16080689 |
| factors that modulate the pkn4 kinase cascade in myxococcus xanthus. | myxococcus xanthus, a gram-negative developmental bacterium, contains a large number of protein ser/thr kinases (pstks). among these pstks, pkn4 is shown to be 6-phosphofructokinase (pfk) kinase. pfk associates with the regulatory domain of pkn4 (pkn4rd) and is activated 2.7-fold upon phosphorylation at thr-226 by pkn4. the activation of pfk is required to consume glycogen accumulated during early development and is essential for efficient sporulation. three new factors, mkapa, mkapb and mkapc h ... | 2005 | 16415588 |
| activation of a development-specific gene, dofa, by frua, an essential transcription factor for development of myxococcus xanthus. | frua is an essential transcription factor for myxococcus xanthus development. the expression of tps and dofa genes is frua dependent. in this study, we show by gel shift and footprint assays with the c-terminal dna-binding domain of frua and by a lacz fusion assay that frua may directly activate dofa expression during development. | 2005 | 16321956 |
| sigf, a new sigma factor required for a motility system of myxococcus xanthus. | a new sigma factor, sigf, was identified from the social and developmental bacterium myxococcus xanthus. sigf is required for fruiting body formation during development as well as social motility during vegetative growth. analysis of gene expression indicates that it is possible that the sigf gene is involved in regulation of an unidentified gene for social motility. | 2005 | 16321963 |
| the bcsa gene influences multiple aspects of development in myxococcus xanthus. | m. xanthus strains containing a mutation in the bcsa gene are able to bypass the b and c signaling requirements for development. the bcsa mutant was examined with regards to several aspects of development to better ascertain the function of the bcsa gene. the bcsa mutant developed on nutrient levels sufficient to support vegetative growth in wild-type cells, supporting previous evidence that the bcsa gene inhibits development. the earliest effect of the bcsa mutation on the development program w ... | 2005 | 16235021 |
| exploitative and hierarchical antagonism in a cooperative bacterium. | social organisms that cooperate with some members of their own species, such as close relatives, may fail to cooperate with other genotypes of the same species. such noncooperation may take the form of outright antagonism or social exploitation. myxococcus xanthus is a highly social prokaryote that cooperatively develops into spore-bearing, multicellular fruiting bodies in response to starvation. here we have characterized the nature of social interactions among nine developmentally proficient s ... | 2005 | 16248676 |
| regulated pole-to-pole oscillations of a bacterial gliding motility protein. | little is known about directed motility of bacteria that move by type iv pilus-mediated (twitching) motility. here, we found that during periodic cell reversals of myxoccocus xanthus, type iv pili were disassembled at one pole and reassembled at the other pole. accompanying these reversals, frzs, a protein required for directed motility, moved in an oscillatory pattern between the cell poles. the frequency of the oscillations was controlled by the frz chemosensory system, which is essential for ... | 2005 | 16272122 |
| four unusual two-component signal transduction homologs, redc to redf, are necessary for timely development in myxococcus xanthus. | we identified a cluster of four two-component signal transduction genes that are necessary for proper progression of myxococcus xanthus through development. redc to redf mutants developed and sporulated early, resulting in small, numerous, and disorganized fruiting bodies. yeast two-hybrid analyses suggest that redcdef act in a single signaling pathway. the previously identified espa gene displays a phenotype similar to that of redcdef. however, combined mutants defective in espa redcdef exhibit ... | 2005 | 16291693 |
| a guild of 45 crispr-associated (cas) protein families and multiple crispr/cas subtypes exist in prokaryotic genomes. | clustered regularly interspaced short palindromic repeats (crisprs) are a family of dna direct repeats found in many prokaryotic genomes. repeats of 21-37 bp typically show weak dyad symmetry and are separated by regularly sized, nonrepetitive spacer sequences. four crispr-associated (cas) protein families, designated cas1 to cas4, are strictly associated with crispr elements and always occur near a repeat cluster. some spacers originate from mobile genetic elements and are thought to confer "im ... | 2005 | 16292354 |
| cloning, sequence analysis and disruption of the mgla gene involved in swarming motility of sorangium cellulosum so ce26, a producer of the antifungal polyketide antibiotic soraphen a. | the myxobacterium sorangium cellulosum so ce26, the producer of the agriculturally important fungicide antibiotic soraphen a, displays coordinated gliding motility (swarming) on agar surfaces. the consequent failure to form detached colonies represents a major obstacle for microbiological and genetic studies, since single cells representing discrete genetic events cannot be reliably separated and propagated as clones. the mgla protein, the product of the mgla gene, has been shown to be a central ... | 2004 | 16233626 |
| comparative biochemical analysis of three bacterial prolyl endopeptidases: implications for coeliac sprue. | prolyl endopeptidases have potential for treating coeliac sprue, a disease of the intestine caused by proteolytically resistant peptides from proline-rich prolamins of wheat, barley and rye. we compared the properties of three similar bacterial prolyl endopeptidases, including the known enzymes from flavobacterium meningosepticum (fm) and sphingomonas capsulate (sc) and a novel enzyme from myxococcus xanthus (mx). these enzymes were interrogated with reference chromogenic substrates, as well as ... | 2004 | 15245330 |
| htha, a putative dna-binding protein, and hthb are important for fruiting body morphogenesis in myxococcus xanthus. | in response to starvation, myxococcus xanthus initiates a developmental programme that results in the formation of spore-filled multicellular fruiting bodies. fruiting body formation depends on the temporal and spatial coordination of aggregation and sporulation and involves temporally and spatially coordinated changes in gene expression. this paper reports the identification of two genes, htha and hthb, that are important for fruiting body formation. htha and hthb are co-transcribed, and transc ... | 2004 | 15256560 |
| mutational analysis of the frua promoter region demonstrates that c-box and 5-base-pair elements are important for expression of an essential developmental gene of myxococcus xanthus. | myxococcus xanthus uses extracellular signals during development to regulate gene expression. c-signaling regulates the expression of many genes induced after 6 h into development. frua is a protein that is necessary for cells to respond to c-signaling, but expression of the frua gene does not depend on c-signaling. yet the frua promoter region has a c box and a 5-bp element, similar to the promoter regions of several c-signal-dependent genes, where these sequences are crucial. here, we show tha ... | 2004 | 15317804 |
| a myxococcus xanthus rppa-mmra double mutant exhibits reduced uptake of amino acids and tolerance of some antimicrobials. | myxococcus xanthus rppa and mmra are homologous to methyl-accepting chemotaxis proteins (mcps) and to multidrug transporters, respectively. we reported previously that rppa-mmra double mutant exhibited reduced colony expansion, agglutination, and polysaccharide levels. we have demonstrated here that the rppa-mmra mutant also exhibited reduced amino acid uptake. furthermore, the double mutant appeared to be more susceptible to some antimicrobial agents, such as streptomycin, ethidium bromide and ... | 2004 | 15336415 |
| the high-mobility group a-type protein card of the bacterium myxococcus xanthus as a transcription factor for several distinct vegetative genes. | card is the only reported prokaryotic protein showing structural and functional features typical of eukaryotic high-mobility group a transcription factors. in prokaryotes, proteins similar to card appear to be confined primarily to myxobacteria. in myxococcus xanthus, card has been previously shown to act as a positive element in two different regulatory networks: one for light-induced synthesis of carotenoids and the other for starvation-induced fruiting body formation. we have now tested the e ... | 2004 | 15342500 |
| aglz is a filament-forming coiled-coil protein required for adventurous gliding motility of myxococcus xanthus. | the aglz gene of myxococcus xanthus was identified from a yeast two-hybrid assay in which mgla was used as bait. mgla is a 22-kda cytoplasmic gtpase required for both adventurous and social gliding motility and sporulation. genetic studies showed that aglz is part of the a motility system, because disruption or deletion of aglz abolished movement of isolated cells and aglz sglk double mutants were nonmotile. the aglz gene encodes a 153-kda protein that interacts with purified mgla in vitro. the ... | 2004 | 15342587 |
| analysis of the frz signal transduction system of myxococcus xanthus shows the importance of the conserved c-terminal region of the cytoplasmic chemoreceptor frzcd in sensing signals. | the frz chemosensory system controls directed motility in myxococcus xanthus by regulating cellular reversal frequency. m. xanthus requires the frz system for vegetative swarming on rich media and for cellular aggregation during fruiting body formation on starvation media. the frz signal transduction pathway is formed by proteins that share homology with chemotaxis proteins from enteric bacteria, which are encoded in the frza-f putative operon and the divergently transcribed frzz gene. frzcd, th ... | 2004 | 15387825 |
| cloning and expression of clt genes encoding milk-clotting proteases from myxococcus xanthus 422. | the screening of a gene library of the milk-clotting strain myxococcus xanthus 422 constructed in escherichia coli allowed the description of eight positive clones containing 26 open reading frames. only three of them (clta, cltb, and cltc) encoded proteins that exhibited intracellular milk-clotting ability in e. coli, saccharomyces cerevisiae, and pichia pastoris expression systems. | 2004 | 15466588 |
| signaling in myxobacteria. | myxobacteria use soluble and cell-contact signals during their starvation-induced formation of fruiting bodies. these signals coordinate developmental gene expression with the cell movements that build fruiting bodies. early in development, the quorum-sensing a-signal in myxococcus xanthus helps to assess starvation and induce the first stage of aggregation. later, the morphogenetic c-signal helps to pattern cell movement and shape the fruiting body. c-signal is a 17-kda cell surface protein tha ... | 2004 | 15487930 |
| structure and function of the shufflon in plasmid r64. | conservative site-specific recombination plays key roles in creating biological diversity in prokaryotes. most site-specific inversion systems consist of two recombination sites and a recombinase gene. in contrast, the shufflon multiple inversion system of plasmid r64 consists of seven sfx recombination sites, which separate four invertible dna segments, and the rci gene encoding a site-specific recombinase of the integrase family. the rci product mediates recombination between any two inverted ... | 2004 | 15493334 |
| a biochemical oscillator explains several aspects of myxococcus xanthus behavior during development. | during development, myxococcus xanthus cells produce a series of spatial patterns by coordinating their motion through a contact-dependent signal, the c-signal. c-signaling modulates the frequency at which cells reverse their gliding direction. it does this by interacting with the frz system (a homolog of the escherichia coli chemosensory system) via a cascade of covalent modifications. here we show that introducing a negative feedback into this cascade results in oscillatory behavior of the sig ... | 2004 | 15496464 |
| reconstruction of the evolutionary history of the lexa-binding sequence. | in recent years, the recognition sequence of the sos repressor lexa protein has been identified for several bacterial clades, such as the gram-positive, green non-sulfur bacteria and cyanobacteria phyla, or the 'alphaproteobacteria', 'deltaproteobacteria' and 'gammaproteobacteria' classes. nevertheless, the evolutionary relationship among these sequences and the proteins that recognize them has not been analysed. fibrobacter succinogenes is an anaerobic gram-negative bacterium that branched from ... | 2004 | 15528664 |
| genetic dissection of the light-inducible carqrs promoter region of myxococcus xanthus. | in myxococcus xanthus photoprotective carotenoids are produced in response to illumination due to regulated expression of carotenoid biosynthesis genes at two loci. induction of the carotenogenesis regulon is dependent on expression of the carqrs operon. the first gene product of the operon, carq, is a sigma factor belonging to the ecf family and is responsible for light-dependent initiation of transcription at the carqrs promoter. we defined the minimal carqrs promoter as a 145-bp fragment of d ... | 2004 | 15547254 |
| cell polarity, intercellular signalling and morphogenetic cell movements in myxococcus xanthus. | in myxococcus xanthus morphogenetic cell movements constitute the basis for the formation of spreading vegetative colonies and fruiting bodies in starving cells. m. xanthus cells move by gliding and gliding motility depends on two polarly localized engines, type iv pili pull cells forward, and slime extruding nozzle-like structures appear to push cells forward. the motility behaviour of cells provides evidence that the two engines are localized to opposite poles and that they undergo polarity sw ... | 2004 | 15556030 |
| characterization of a myxococcus xanthus mutant that is defective for adventurous motility and social motility. | myxococcus xanthus is a gliding bacterium that possesses two motility systems, the adventurous (a-motility) and social (s-motility) systems. a-motility is used for individual cell gliding, while s-motility is used for gliding in multicellular groups. video microscopy studies showed that nla24 cells are non-motile on agar surfaces, suggesting that the nla24 gene product is absolutely required for both a-motility and s-motility under these assay conditions. s-motility requires functional type iv p ... | 2004 | 15583161 |
| mutational analysis of the myxococcus xanthus omega4400 promoter region provides insight into developmental gene regulation by c signaling. | myxococcus xanthus utilizes extracellular signals during development to coordinate cell movement, differentiation, and changes in gene expression. one of these signals, the c signal, regulates the expression of many genes, including omega4400, a gene identified by an insertion of tn5 lac into the chromosome. expression of tn5 lac omega4400 is reduced in csga mutant cells, which fail to perform c signaling, and the promoter region has several sequences similar to sequences found in the regulatory ... | 2004 | 14729691 |
| evolution of cooperation: two for one? | how can cooperation thrive in a selfish world? recent evolution experiments show how bacteria themselves can generate conditions that make cooperation a winning strategy. at least in the short term. | 2004 | 14738754 |
| dynamics of fruiting body morphogenesis. | myxobacteria build their species-specific fruiting bodies by cell movement and then differentiate spores in specific places within that multicellular structure. new steps in the developmental aggregation of myxococcus xanthus were discovered through a frame-by-frame analysis of a motion picture. the formation and fate of 18 aggregates were captured in the time-lapse movie. still photographs of 600 other aggregates were also analyzed. m. xanthus has two engines that propel the gliding of its rod- ... | 2004 | 14761986 |
| myxococcus xanthus chemotaxis homologs difd and difg negatively regulate fibril polysaccharide production. | the extracellular matrix fibrils of myxococcus xanthus are essential for the social lifestyle of this unusual bacterium. these fibrils form networks linking or encasing cells and are tightly correlated with cellular cohesion, development, and social (s) gliding motility. previous studies identified a set of bacterial chemotaxis homologs encoded by the dif locus. it was determined that difa, difc, and dife, encoding respective homologs of a methyl-accepting chemotaxis protein, chew, and chea, are ... | 2004 | 14761994 |
| rippling of myxobacteria. | myxobacteria colonies during their aggregation phase propagate complex waves over their surface. these waves are fundamentally different from the analogous phenomenon in diffusion-reaction systems or in populations of dictyostelium discoideum where colliding waves annhilate. myxobacterial waves appear to pass through one another, analogous to solitons. moreover, individual bacteria oscillate back and forth, exhibiting no net mass transfer. a mathematical model can explain virtually all of the ex ... | 2004 | 14766104 |
| rppa, a transducer homologue, and mmra, a multidrug transporter homologue, are involved in the biogenesis and/or assembly of polysaccharide in myxococcus xanthus. | myxococcus xanthus cells move by gliding, and form multicellular fruiting bodies under conditions of starvation. the authors cloned a gene, designated rppa (for receptor for polysaccharide production), which encodes a methyl-accepting protein homologous to the chemotaxis transducers in eubacteria. the rppa gene was co-transcribed with mmra, a gene homologous to various multidrug transporter genes. the rppa or mmra single mutants showed almost identical phenotypes to the wild-type strain; however ... | 2004 | 14993312 |
| strategies of microbial cheater control. | the potential benefits of cooperation in microorganisms can be undermined by genetic conflict within social groups, which can take the form of 'cheating'. for cooperation to succeed as an evolutionary strategy, the negative effects of such conflict must somehow be either prevented or mitigated. to generate an interpretive framework for future research in microbial behavioural ecology, here we outline a wide range of hypothetical mechanisms by which cheaters might be constrained. | 2004 | 15036323 |
| [effect of uv-radiation and drying on bacterium diversity in soil]. | it has been shown that after dna-injuring factors (uv irradiation or drying) action on soil one could observe the decrease of the total quantity of bacteria and the number of species, i.e., the decrease of microbe diversity. at the same time not numerous species were found in soils after their action. thus the drying or uv-irradiation makes it possible to estimate more completely the microbe diversity in soils as well as to find resistant bacteria. it has been established that the strain methylo ... | 2004 | 15104058 |
| operator design and mechanism for cara repressor-mediated down-regulation of the photoinducible carb operon in myxococcus xanthus. | the carb operon encodes all except one of the enzymes involved in light-induced carotenogenesis in myxococcus xanthus. expression of its promoter (p(b)) is repressed in the dark by sequence-specific dna binding of cara to a palindrome (pi) located between positions -47 and -64 relative to the transcription start site. this promotes subsequent binding of cara to additional sites that remain to be defined. cars, produced in the light, interacts physically with cara, abrogates cara-dna binding, and ... | 2004 | 15123730 |
| nsd, a locus that affects the myxococcus xanthus cellular response to nutrient concentration. | expression of the previously reported tn5lac omega4469 insertion in myxococcus xanthus cells is regulated by the starvation response. interested in learning more about the starvation response, we cloned and sequenced the region containing the insertion. our analysis shows that the gene fusion is located in an open reading frame that we have designated nsd (nutrient sensing/utilizing defective) and that its expression is driven by a sigma70-like promoter. sequence analysis of the nsd gene product ... | 2004 | 15150233 |
| the n terminus of myxococcus xanthus cara repressor is an autonomously folding domain that mediates physical and functional interactions with both operator dna and antirepressor protein. | expression of the myxococcus xanthus carb operon, which encodes the majority of the enzymes involved in light-induced carotenogenesis, is down-regulated in the dark by the cara repressor binding to its bipartite operator. cars, produced on illumination, relieves repression of carb by physically interacting with cara to dis-mantle cara-dna complexes. here, we demonstrate that the n- and c-terminal portions of cara are organized as distinct structural and functional domains. specifically, we show ... | 2004 | 15163666 |
| biosynthesis of volatiles by the myxobacterium myxococcus xanthus. | the volatiles emitted from cell cultures of myxobacterium myxococcus xanthus were collected by use of a closed-loop stripping apparatus (clsa) and analyzed by gc-ms. two new natural products, (s)-9-methyldecan-3-ol ((s)-1) and 9-methyldecan-3-one (2), were identified and synthesized, together with other aliphatic ketones and alcohols, and terpenes. biosynthesis of the two main components (s)-1 and 2 was examined in feeding experiments carried out with the wild-type strain dk1622 and two mutant s ... | 2004 | 15174160 |
| mutational analysis of the myxococcus xanthus omicron4499 promoter region reveals shared and unique properties in comparison with other c-signal-dependent promoters. | the bacterium myxococcus xanthus undergoes multicellular development during times of nutritional stress and uses extracellular signals to coordinate cell behavior. c-signal affects gene expression late in development, including that of omega4499, an operon identified by insertion of tn5 lac into the m. xanthus chromosome. the omega4499 promoter region has several sequences in common with those found previously to be important for expression of other c-signal-dependent promoters. to determine if ... | 2004 | 15175290 |
| the che4 pathway of myxococcus xanthus regulates type iv pilus-mediated motility. | myxococcus xanthus co-ordinates cell movement during its complex life cycle using multiple chemotaxis-like signal transduction pathways. these pathways regulate both type iv pilus-mediated social (s) motility and adventurous (a) motility. during a search for new chemoreceptors, we identified the che4 operon, which encodes homologues to a mcp (methyl-accepting chemotaxis protein), two chews, a hybrid chea-chey, a response regulator and a cher. deletion of the che4 operon did not cause swarming or ... | 2004 | 15186426 |
| sigma54 enhancer binding proteins and myxococcus xanthus fruiting body development. | a search of the m1genome sequence, which includes 97% of the myxococcus xanthus genes, identified 53 sequence homologs of sigma54-dependent enhancer binding proteins (ebps). a dna microarray was constructed from the m1genome that includes those homologs and 318 other m. xanthus genes for comparison. to screen the developmental program with this array, an rna extract from growing cells was compared with one prepared from developing cells at 12 h. previous reporter studies had shown that m. xanthu ... | 2004 | 15205438 |
| analysis of frue, a novel developmental gene of myxococcus xanthus. | myxococcus xanthus is a gram-negative soil bacterium that undergoes multicellular development upon nutrient starvation. in the present study, a tnv insertion developmental mutation, omega773, of m. xanthus was analyzed. the tnv omega773 insertion was found to be located within a novel developmental gene, frue. the frue protein is composed of 140 amino acid residues and bears an n-terminal signal peptide. the amino acid sequence of frue shared no significant similarity with any other known protei ... | 2003 | 15153769 |
| coupling cell movement to multicellular development in myxobacteria. | the myxobacteria are gram-negative organisms that are capable of multicellular, social behaviour. in the presence of nutrients, swarms of myxobacteria feed cooperatively by sharing extracellular digestive enzymes, and can prey on other bacteria. when the food supply runs low, they initiate a complex developmental programme that culminates in the production of a fruiting body. myxobacteria move by gliding and have two, polarly positioned engines to control their motility. the two engines undergo ... | 2003 | 15040179 |
| a novel regulatory gene for light-induced carotenoid synthesis in the bacterium myxococcus xanthus. | myxococcus xanthus cells respond to blue light by producing carotenoids. light triggers a network of regulatory actions that lead to the transcriptional activation of the carotenoid genes. by screening the colour phenotype of a collection of tn5-lac insertion mutants, we have isolated a new mutant devoid of carotenoid synthesis. we map the transposon insertion, which co-segregates with the mutant phenotype, to a previously unknown gene designated here as carf. an in frame deletion within carf ca ... | 2003 | 12519205 |
| role of two novel two-component regulatory systems in development and phosphatase expression in myxococcus xanthus. | we have cloned a two-component regulatory system (phor2-phop2) of myxococcus xanthus while searching for genes that encode proteins with phosphatase activity, where phor2 encodes the histidine kinase and phop2 encodes the response regulator. a second system, phor3-phop3, was identified and isolated by using phop2 as a probe. these two systems are quite similar, sharing identities along the full-length proteins of 52% on the histidine kinases and 64% on the response regulators. the predicted stru ... | 2003 | 12562808 |
| cis elements necessary for developmental expression of a myxococcus xanthus gene that depends on c signaling. | cell contact-mediated c signaling coordinates morphogenesis and gene expression during development of myxococcus xanthus. one promoter that depends on c signaling for transcription lies upstream of omega4403, the site of a tn5 lac insertion in the genome. the omega4403 promoter has a c-box sequence centered at -49 bp that matches the consensus 5'-cayyccy-3', which is found in several c-signal-dependent promoters. mutational analysis of the omega4403 promoter region was performed to test the impo ... | 2003 | 12562812 |