Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| eukaryotic-like signaling and gene regulation in a prokaryote that undergoes multicellular development. | 2005 | 15710872 | |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| [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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| myxococcus xanthus twin-arginine translocation system is important for growth and development. | the twin-arginine translocation (tat) system serves to export fully folded proteins across the cytoplasmic membrane. in many bacteria, three major components, tata, tatb and tatc, are the functionally essential constituents of the tat system. a myxococcus xanthus tatb-tatc deletion mutant could aggregate and form mounds, but was unable to form fruiting bodies under nutritionally limiting conditions. when tatb-tatc mutant vegetative cells were cultured with 0.5 m glycerol, the cell morphology cha ... | 2006 | 16331440 |
| differential effects of chemoreceptor methylation-domain mutations on swarming and development in the social bacterium myxococcus xanthus. | the soil bacterium myxococcus xanthus is a model organism for the study of multicellular behaviour and development in bacteria. m. xanthus cells move on solid surfaces by gliding motility, periodically reversing their direction of movement. motility is co-ordinated to allow cells to effectively feed on macromolecules or prey bacteria when nutrients are plentiful and to form developmental fruiting bodies when nutrients are limiting. the frz signal transduction pathway regulates cellular movements ... | 2006 | 16359317 |
| accordion waves in myxococcus xanthus. | myxococcus xanthus are gram-negative bacteria that glide on solid surfaces, periodically reversing their direction of movement. when starved, m. xanthus cells organize their movements into waves of cell density that sweep over the colony surface. these waves are unique: although they appear to interpenetrate, they actually reflect off one another when they collide, so that each wave crest oscillates back and forth with no net displacement. because the waves reflect the coordinated back and forth ... | 2006 | 16432222 |
| nonribosomal peptide biosynthesis: point mutations and module skipping lead to chemical diversity. | 2006 | 16506259 | |
| mutational analysis of the myxococcus xanthus omega4406 promoter region reveals an upstream negative regulatory element that mediates c-signal dependence. | c signaling plays a key role in coordinating cell movement and differentiation during the multicellular developmental process of myxococcus xanthus. c signaling regulates expression of genes induced after about 6 h into development, when cells are forming mounds. one gene whose expression depends absolutely on c signaling was identified by insertion of a transposable element at site omega4406 which generated a transcriptional fusion between lacz and an upstream promoter. we have investigated reg ... | 2006 | 16385042 |
| the orphan response regulator digr is required for synthesis of extracellular matrix fibrils in myxococcus xanthus. | in myxococcus xanthus, two-component systems have crucial roles in regulating motility behavior and development. here we describe an orphan response regulator, consisting of an n-terminal receiver domain and a c-terminal dna binding domain, which is required for a and type iv pilus-dependent gliding motility. genetic evidence suggests that phosphorylation of the conserved, phosphorylatable aspartate residue in the receiver domain is required for digr activity. consistent with the defect in type ... | 2006 | 16740945 |
| cohesion-defective mutants of myxococcus xanthus. | cohesion of myxococcus xanthus cells involves interaction of a cell surface cohesin with a component of the extracellular matrix. in this work, two previously isolated cohesion-defective (fbd) mutants were characterized. the fbda and fbdb genes do not encode the cohesins but are necessary for their production. both mutants produce type iv pili, suggesting that pila is not a major cohesin. | 2006 | 16740967 |
| a novel regulation on developmental gene expression of fruiting body formation in myxobacteria. | myxobacteria are gram-negative soil microorganisms that prey on other microorganisms. myxobacteria have significant potential for applications in biotechnology because of their extraordinary ability to produce natural products such as secondary metabolites. myxobacteria also stand out as model organisms for the study of cell-cell interactions and multicellular development during their complex life cycle. cellular morphogenesis during multicellular development in myxobacteria is very similar to t ... | 2006 | 16791590 |
| contribution of the cyclic nucleotide phosphodiesterases pdea and pdeb to adaptation of myxococcus xanthus cells to osmotic or high-temperature stress. | a tblastn search of the myxococcus xanthus genome database at the institute for genomic research (tigr) identified three genes (pdea, pdeb, and pdec) that encode proteins homologous to 3',5'-cyclic nucleotide phosphodiesterase. pdea, pdeb, and pdec mutants, constructed by replacing a part of the gene with the kanamycin or tetracycline resistance gene, showed normal growth, development, and germination under nonstress conditions. however, the spores of mutants, especially the pdea and pdeb mutant ... | 2006 | 16385075 |
| distinguishing features of delta-proteobacterial genomes. | we analyzed several features of five currently available delta-proteobacterial genomes, including two aerobic bacteria exhibiting predatory behavior and three anaerobic sulfate-reducing bacteria. the delta genomes are distinguished from other bacteria by several properties: (i) the delta genomes contain two "giant" s1 ribosomal protein genes in contrast to all other bacterial types, which encode a single or no s1; (ii) in most delta-proteobacterial genomes the major ribosomal protein (rp) gene c ... | 2006 | 16844781 |
| a myxobacterial s-motility protein dances with poles. | coordinated movement of packs of s-motile myxococcus xanthus cells relies on extrusion and retraction of pili that are located at one cell pole. at regular intervals the pili switch their polar location and cells reverse direction. recently, the frzs s-motility protein was observed to localize predominantly to the piliated pole. in time, frzs was redeployed to the opposite pole and its sequestration at the new site coincided with cell reversal. the c-terminal region of frzs, a response regulator ... | 2006 | 16677816 |
| gliding motility: anticipating the next move with a molecular clock. | frzs protein is important for normal social motility in myxobacteria, which includes periodic reversals in the direction of cell motion. recent results show that cell reversal correlates with the migration of frzs from the old leading pole of the cell to the new leading pole. | 2006 | 16461268 |
| integration into the phage attachment site, attb, impairs multicellular differentiation in stigmatella aurantiaca. | stigmatella aurantiaca displays a complex developmental life cycle in response to starvation conditions that results in the formation of tree-like fruiting bodies capable of producing spores. the phage mx8, first isolated from the close relative myxococcus xanthus, is unable to infect s. aurantiaca cells and integrate into the genome. however, plasmids containing mx8 fragments encoding the integrase and attp are able to integrate at the attb locus in the s. aurantiaca genome by site-specific rec ... | 2006 | 16484181 |
| rippling is a predatory behavior in myxococcus xanthus. | cells of myxococcus xanthus will, at times, organize their movement such that macroscopic traveling waves, termed ripples, are formed as groups of cells glide together on a solid surface. the reason for this behavior has long been a mystery, but we demonstrate here that rippling is a feeding behavior which occurs when m. xanthus cells make direct contact with either prey or large macromolecules. rippling has been observed during two fundamentally distinct environmental conditions: (i) starvation ... | 2006 | 16885457 |
| nla18, a key regulatory protein required for normal growth and development of myxococcus xanthus. | ntrc-like activators regulate the transcription of a wide variety of adaptive genes in bacteria. previously, we demonstrated that a mutation in the ntrc-like activator gene nla18 causes defects in fruiting body development in myxococcus xanthus. in this report, we describe the effect that nla18 inactivation has on gene expression patterns during development and vegetative growth. gene expression in nla18 mutant cells is altered in the early stages of fruiting body development. furthermore, nla18 ... | 2006 | 16484184 |
| phospholipid directed motility of surface-motile bacteria. | myxococcus xanthus is a surface-motile bacterium that has adapted at least one chemosensory system to allow directed movement towards the slowly diffusible lipid phosphatidylethanolamine (pe). the dif chemosensory pathway is remarkable because it has at least three inputs coupled to outputs that control extracellular matrix (ecm) production and lipid chemotaxis. the methyl-accepting chemotaxis protein, difa, has two different sensor inputs that have been localized by mutagenesis. the dif chemose ... | 2006 | 16925549 |
| secretins take shape. | secretins are a unique class of bacterial multimeric outer membrane proteins that probably differ considerably from other, less complex outer membrane proteins in their overall structure and organization, and in their requirements for outer membrane targeting and assembly factors. in this microcommentary, we discuss these differences with respect to the role of a specific class of lipoproteins, often referred to as pilotins, in secretin complex assembly. we compare them with other lipoproteins t ... | 2006 | 16556215 |
| polar assembly of the type iv pilus secretin in myxococcus xanthus. | the type iv pilus filament of myxococcus xanthus penetrates the outer membrane through a gated channel--the pilq secretin. assembly of the channel and formation of pilq multimeric complexes that resist disassembly in heated detergent is correlated with the release of a 50 kda fragment of pilq. tgl lipoprotein is required for pilq assembly in m. xanthus, because pilq monomers but no heat and detergent-resistant complexes are present in a strain from which tgl has been deleted. pilq protein is oft ... | 2006 | 16556217 |
| a square archaeon, the smallest eukaryote and the largest bacteria. | 2006 | 16958749 | |
| 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 |
| cbga, a protein involved in cortex formation and stress resistance in myxococcus xanthus spores. | cbga plays a role in cortex formation and the acquisition of a subset of stress resistance properties in myxococcus xanthus spores. the cbga mutant produces spores with thin or no cortex layers, and these spores are more sensitive to heat and sodium dodecyl sulfate than their wild-type counterparts. | 2006 | 16997953 |
| reconstitution of the myxothiazol biosynthetic gene cluster by red/et recombination and heterologous expression in myxococcus xanthus. | although many secondary metabolites exhibiting important pharmaceutical and agrochemical activities have been isolated from myxobacteria, most of these microorganisms remain difficult to handle genetically. to utilize their metabolic potential, heterologous expression methodologies are currently being developed. here, the red/et recombination technology was used to perform all required gene cluster engineering steps in escherichia coli prior to the transfer into the chromosome of the heterologou ... | 2006 | 16997979 |
| rational design of combination enzyme therapy for celiac sprue. | celiac sprue (also known as celiac disease) is an inheritable, gluten-induced enteropathy of the upper small intestine with an estimated prevalence of 0.5%-1% in most parts of the world. the ubiquitous nature of food gluten, coupled with inadequate labeling regulations in most countries, constantly poses a threat of disease exacerbation and relapse for patients. here, we demonstrate that a two-enzyme cocktail comprised of a glutamine-specific cysteine protease (ep-b2) that functions under gastri ... | 2006 | 16793522 |
| a microbial genetic journey. | fortunately, i began research in 1950 when the basic concepts of microbial genetics could be explored experimentally. i began with bacteriophage lambda and tried to establish the colinearity of its linkage map with its dna molecule. my students and i worked out the regulation of lambda repressor synthesis for the establishment and maintenance of lysogeny. we also investigated the proteins responsible for assembly of the phage head. using cell extracts, we discovered how to package dna inside the ... | 2006 | 16824011 |
| [induction of bacillus anthracis hemolytic activity with the use of myxococcus xanthus]. | the development of a new method for the induction of the b. anthracis hemolytic activity with the use of m. xanthus and the differentiation of pure cultures of the causative agent of anthrax from those contaminated with myxobacteria is presented. to demonstrate the induction of the hemolytic acivity of b. anthracis with the use of m. xanthus, conditions for the symbiosis of b. anthracis cells sti, exhibiting no hemolytic activity, with m. xanthus non-hemolytic cells were created by mixing them a ... | 2006 | 16830581 |
| myxovirescin a biosynthesis is directed by hybrid polyketide synthases/nonribosomal peptide synthetase, 3-hydroxy-3-methylglutaryl-coa synthases, and trans-acting acyltransferases. | myxococcus xanthus dk1622 is shown to be a producer of myxovirescin (antibiotic ta) antibiotics. the myxovirescin biosynthetic gene cluster spans at least 21 open reading frames (orfs) and covers a chromosomal region of approximately 83 kb. in silico analysis of myxovirescin orfs in conjunction with genetic studies suggests the involvement of four type i polyketide synthases (pkss; tai, tal, tao, and tap), one major hybrid pks/nrps (ta-1), and a number of monofunctional enzymes similar to the on ... | 2006 | 16835859 |
| straight-chain fatty acids are dispensable in the myxobacterium myxococcus xanthus for vegetative growth and fruiting body formation. | inactivation of the mxan_0853 gene blocked the production in myxococcus xanthus of straight-chain fatty acids which otherwise represent 30% of total fatty acids. despite this drastic change in the fatty acid profile, no change in phenotype could be observed, which contrasts with previous interpretations of the role of straight-chain fatty acids in the organism's development. | 2006 | 16855254 |
| lysophosphatidylethanolamine is a substrate for the short-chain alcohol dehydrogenase soca from myxococcus xanthus. | short-chain alcohol dehydrogenases (scadhs) synthesize a variety of intercellular signals and other chemically diverse products. it is difficult to predict the substrate of a scadh on the basis of amino acid sequence homology, as the substrates are not known for most scadhs. in myxococcus xanthus, the scadh csga is responsible for c signaling during fruiting body development, although the mechanism is unclear. overexpression of the scadh soca compensates for the lack of csga and restores develop ... | 2006 | 17028273 |
| type iv pili function upstream of the dif chemotaxis pathway in myxococcus xanthus eps regulation. | the developmental bacterium myxococcus xanthus utilizes gliding motility to aggregate during the formation of multicellular fruiting bodies. the social (s) component of m. xanthus gliding motility requires at least two extracellular surface structures, type iv pili (tfp) and the fibril polysaccharide or exopolysaccharide (eps). retraction of tfp is proposed to power s motility and eps from neighbouring cells is suggested to provide an anchor and trigger for tfp retraction. the production of eps ... | 2006 | 16856943 |
| role of sigmad in regulating genes and signals during myxococcus xanthus development. | starvation-induced development of myxococcus xanthus is an excellent model for biofilm formation because it involves cell-cell signaling to coordinate formation of multicellular mounds, gene expression, and cellular differentiation into spores. the role of sigma(d), an alternative sigma factor important for viability in stationary phase and for stress responses, was investigated during development by measuring signal production, gene expression, and sporulation of a sigd null mutant alone and up ... | 2006 | 16621817 |
| the response regulator phop4 is required for late developmental events in myxococcus xanthus. | phosphate regulation is complex in the developmental prokaryote myxococcus xanthus, and requires at least four two-component systems (tcss). here, the identification and characterization of a member of one tcs, designated phop4, is reported. phop4 insertion and in-frame deletion strains caused spore viability to be decreased by nearly two orders of magnitude, and reduced all three development-specific phosphatase activities by 80-90 % under phosphate-limiting conditions. microarray and quantitat ... | 2006 | 16735725 |
| a protein ser/thr kinase cascade negatively regulates the dna-binding activity of mrpc, a smaller form of which may be necessary for the myxococcus xanthus development. | the developmental process of myxococcus xanthus is achieved by the expression of a specific set of genes under the influence of developmental signals. mrpc is a member of the crp family of transcription regulators, essential for frua expression during development. the pkn8-pkn14 protein kinase cascade negatively regulates mrpc expression (h. nariya and s. inouye, 2005. mol microbiol 58: 367-379). elevated levels of mrpc in pkn8 and pkn14 deletion strains (deltapkn8 and deltapkn14) induce untimel ... | 2006 | 16689796 |
| 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 |
| sociobiology: the phoenix effect. | 2006 | 16710402 | |
| two ser/thr protein kinases essential for efficient aggregation and spore morphogenesis in myxococcus xanthus. | myxococcus xanthus has a complex life cycle that involves vegetative growth and development. previously, we described the espab locus that is involved in timing events during the initial stages of fruiting body formation. deletion of espa caused early aggregation and sporulation, whereas deletion of espb caused delayed aggregation and sporulation resulting in reduced spore yields. in this study, we describe two genes, pkta5 and pktb8, that flank the espab locus and encode ser/thr protein kinase ... | 2006 | 16796678 |
| the unique dkxanthene secondary metabolite family from the myxobacterium myxococcus xanthus is required for developmental sporulation. | under starvation conditions myxobacteria form multicellular fruiting bodies in which vegetative cells differentiate into heat- and desiccation-resistant myxospores. myxobacteria in general are a rich source of secondary metabolites that often exhibit biological activities rarely found in nature. although the involvement of a yellow compound in sporulation and fruiting body formation of myxococcus xanthus was described almost 30 years ago, the chemical principle of the pigment remained elusive. t ... | 2006 | 17148609 |
| cyanobacterial response regulator pata contains a conserved n-terminal domain (patan) with an alpha-helical insertion. | the cyanobacterium anabaena (nostoc) pcc 7120 responds to starvation for nitrogen compounds by differentiating approximately every 10th cell in the filament into nitrogen-fixing cells called heterocysts. heterocyst formation is subject to complex regulation, which involves an unusual response regulator pata that contains a chey-like phosphoacceptor (receiver, rec) domain at its c-terminus. pata-like response regulators are widespread in cyanobacteria; one of them regulates phototaxis in synechoc ... | 2006 | 16543275 |
| a new class of [2fe-2s]-cluster-containing protoporphyrin (ix) ferrochelatases. | protoporphyrin (ix) ferrochelatase catalyses the insertion of ferrous iron into protoporphyrin ix to form haem. these ferrochelatases exist as monomers and dimers, both with and without [2fe-2s] clusters. the motifs for [2fe-2s] cluster co-ordination are varied, but in all cases previously reported, three of the four cysteine ligands are present in the 30 c-terminal residues and the fourth ligand is internal. in the present study, we demonstrate that a group of micro-organisms exist which posses ... | 2006 | 16548850 |
| 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 |
| genetic population structure of the soil bacterium myxococcus xanthus at the centimeter scale. | myxococcus xanthus is a gram-negative soil bacterium best known for its remarkable life history of social swarming, social predation, and multicellular fruiting body formation. very little is known about genetic diversity within this species or how social strategies might vary among neighboring strains at small spatial scales. to investigate the small-scale population structure of m. xanthus, 78 clones were isolated from a patch of soil (16 by 16 cm) in tübingen, germany. among these isolates, 2 ... | 2006 | 16672510 |
| transposon insertions of magellan-4 that impair social gliding motility in myxococcus xanthus. | myxococcus xanthus has two different mechanisms of motility, adventurous (a) motility, which permits individual cells to glide over solid surfaces, and social (s) motility, which permits groups of cells to glide. to identify the genes involved in s-gliding motility, we mutagenized a delta aglu (a-) strain with the defective transposon, magellan-4, and screened for s- mutants that form nonmotile colonies. sequence analysis of the sites of the magellan-4 insertions in these mutants and the alignme ... | 2006 | 16299386 |
| genetic control for light-induced carotenoid production in non-phototrophic bacteria. | carotenoids are naturally occurring yellow or orange pigments that serve as a protectant against photo-oxidative damages. among the wide variety of producers, the prokaryotes generate a broad spectrum of carotenoids with diverse chemical structures that are expected to have a high potential in biotechnological applications. bacterial carotenogenesis occurs in a constitutive or light-induced manner, which suggests the diversity of the regulatory mechanism. the mechanism for light-induced caroteno ... | 2006 | 16091943 |
| self-organized and highly ordered domain structures within swarms of myxococcus xanthus. | coordinated group movement (swarming) is a key aspect of myxococcus xanthus' social behavior. here we report observation of domain structures formed by multiple cells within large three-dimensional swarming groups grown on amorphous glass substrates, using the atomic force microscope (afm). novel analyses revealed that 90% of the wild type swarms displayed some form of preferential cell alignment. in contrast, cells with mutations in the social and adventurous motility systems displayed a distin ... | 2006 | 16421928 |
| regulation of the myxococcus xanthus c-signal-dependent omega4400 promoter by the essential developmental protein frua. | the bacterium myxococcus xanthus employs extracellular signals to coordinate aggregation and sporulation during multicellular development. extracellular, contact-dependent signaling that involves the csga protein (called c-signaling) activates frua, a putative response regulator that governs a branched signaling pathway inside cells. one branch regulates cell movement, leading to aggregation. the other branch regulates gene expression, leading to sporulation. c-signaling is required for full exp ... | 2006 | 16816188 |
| recruitment of a novel zinc-bound transcriptional factor by a bacterial hmga-type protein is required for regulating multiple processes in myxococcus xanthus. | enhanceosome assembly in eukaryotes often requires high mobility group a (hmga) proteins. in prokaryotes, the only known transcriptional regulator with hmga-like physical, structural and dna-binding properties is myxococcus xanthus card. here, we report that every card-regulated process analysed also requires the product of gene carg, located immediately downstream of and transcriptionally coupled to card. carg has the zinc-binding h/c-rich metallopeptidase motif found in archaemetzincins, but w ... | 2006 | 16879646 |
| two continuum models for the spreading of myxobacteria swarms. | we analyze the phenomenon of spreading of a myxococcus xanthus bacterial colony on plates coated with nutrient. the bacteria spread by gliding on the surface. in the first few hours, cell growth is irrelevant to colony spread. in this case, bacteria spread through peninsular protrusions from the edge of the initial colony. we analyze the diffusion through the narrowing reticulum of cells on the surface mathematically and derive formulae for the spreading rates. on the time scale of tens of hours ... | 2006 | 16802086 |