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xanthusbase after five years expands to become openmods.xanthusbase (http://www.xanthusbase.org), a model organism database for the bacterium myxococcus xanthus, functions as a collaborative information repository based on wikipedia principles. it was created more than 5 years ago to serve as a cost-effective reference database for m. xanthus researchers, an education tool for undergraduate students to learn about genome annotation, and a means for the community of researchers to collaboratively improve their organism's annotation. we have achieved s ...201222116063
From individual cell motility to collective behaviors: insights from a prokaryote, Myxococcus xanthus.In bird flocks, fish schools, and many other living organisms, regrouping among individuals of the same kin is frequently an advantageous strategy to survive, forage, and face predators. However, these behaviors are costly because the community must develop regulatory mechanisms to coordinate and adapt its response to rapid environmental changes. In principle, these regulatory mechanisms, involving communication between individuals, may also apply to cellular systems which must respond collectiv ...201222091711
direct visualization of the interaction between pilin and exopolysaccharides of myxococcus xanthus with egfp-fused pila protein.type iv pili (tfp) and exopolysaccharides (eps) are important components for social behaviors in myxococcus xanthus, including gliding motility and fruiting body formation. although specific interactions between tfp and eps have been proposed, there have as yet been no direct observations of these interactions under native conditions. in this study, we found that a truncated pila protein (pilact) containing only the c-terminal domain (amino acids 32-208) is sufficient for eps binding in vitro. f ...201222092602
Myxococcus xanthus swarms are driven by growth and regulated by a pacemaker.The principal social activity of Myxococcus xanthus is to organize a dynamic multicellular structure, known as a swarm. Although its cell density is high, the swarm can grow and expand rapidly. Within the swarm, the individual rod-shaped cells are constantly moving, transiently interacting with one another, and independently reversing their gliding direction. Periodic reversal is, in fact, essential for creating a swarm, and the reversal frequency controls the rate of swarm expansion. Chemotaxis ...201121856842
gtpases in bacterial cell polarity and signalling.in bacteria, large g domain gtpases have well-established functions in translation, protein translocation, trna modification and ribosome assembly. in addition, bacteria also contain small ras-like gtpases consisting of stand-alone g domains. recent data have revealed that small ras-like gtpases as well as large g domain gtpases in bacteria function in the regulation of cell polarity, signal transduction and possibly also in cell division. the small ras-like gtpase mgla together with its cognate ...201121955886
Uncovering the mystery of gliding motility in the myxobacteria.Bacterial gliding motility is the smooth movement of cells on solid surfaces unaided by flagella or pili. Many diverse groups of bacteria exhibit gliding, but the mechanism of gliding motility has remained a mystery since it was first observed more than a century ago. Recent studies on the motility of Myxococcus xanthus, a soil myxobacterium, suggest a likely mechanism for gliding in this organism. About forty M. xanthus genes were shown to be involved in gliding motility, and some of their prot ...201121910630
Porphyrin Biosynthesis Control under Water Stress: Sustained Porphyrin Status Correlates with Drought Tolerance in Transgenic Rice.A controlled flow of porphyrin metabolites is critical for organisms, but little is known about the control of porphyrin biosynthesis under environmental stress. We monitored transgenic rice (Oryza sativa) plants expressing Myxococcus xanthus protoporphyrinogen oxidase (PPO) for their response to drought stress. Transgenic plants showed significantly improved drought tolerance, as indicated by a higher shoot water potential, less oxidative damage, and a more favorable redox balance compared with ...201122021420
protoporphyrinogen oxidase inhibitor: an ideal target for herbicide discovery.as the last common enzyme in the biosynthetic pathway leading to heme and chlorophyll, protoporphyrinogen oxidase (ppo; ec 1.3.3.4) is an ideal target for herbicide development. currently, about 30 ppo inhibitors have been developed as agricultural herbicides. ppo inhibitors have displayed environmentally benign, but advantageous characteristics, including low toxicity, low effective concentration, broad herbicidal spectrum (active against both monocotyledon and dicotyledon weeds), quick onset ...201122273380
myxoprincomide: a natural product from myxococcus xanthus discovered by comprehensive analysis of the secondary metabolome.come to the fore: the novel myxobacterial metabolite myxoprincomide is easy to overlook in the complex lc-ms data recorded for the metabolome of myxococcus xanthus dk1622, such that advanced analytical techniques were needed for its discovery. by enhancing genomics-based natural products research with powerful analytical tools for in-depth metabolome mining, two additional such "hidden" metabolites have been uncovered.201122162209
molecular monitoring of the microbial dynamics occurring on historical limestone buildings during and after the in situ application of different bio-consolidation treatments.microbially induced carbonate precipitation is proposed as an environmentally friendly method to protect decayed ornamental stone and introduced in the field of preservation of cultural heritage. recent conservation studies performed under laboratory conditions on non-sterile calcarenite stones have successfully reported on the application of a suitable nutritional solution, inoculated and non-inoculated with myxococcus xanthus, as a bioconsolidation treatment. furthermore, this procedure has be ...201121944202
emergence and modular evolution of a novel motility machinery in bacteria.bacteria glide across solid surfaces by mechanisms that have remained largely mysterious despite decades of research. in the deltaproteobacterium myxococcus xanthus, this locomotion allows the formation stress-resistant fruiting bodies where sporulation takes place. however, despite the large number of genes identified as important for gliding, no specific machinery has been identified so far, hampering in-depth investigations. based on the premise that components of the gliding machinery must h ...201121931562
FrzS regulates social motility in Myxococcus xanthus by controlling exopolysaccharide production.Myxococcus xanthus Social (S) motility occurs at high cell densities and is powered by the extension and retraction of Type IV pili which bind ligands normally found in matrix exopolysaccharides (EPS). Previous studies showed that FrzS, a protein required for S-motility, is organized in polar clusters that show pole-to-pole translocation as cells reverse their direction of movement. Since the leading cell pole is the site of both the major FrzS cluster and type IV pilus extension/retraction, it ...201121886839
Structural analysis of the Ras-like G protein MglA and its cognate GAP MglB and implications for bacterial polarity.The bacterium Myxococcus xanthus uses a G protein cycle to dynamically regulate the leading/lagging pole polarity axis. The G protein MglA is regulated by its GTPase-activating protein (GAP) MglB, thus resembling Ras family proteins. Here, we show structurally and biochemically that MglA undergoes a dramatic, GDP-GTP-dependent conformational change involving a screw-type forward movement of the central ß2-strand, never observed in any other G protein. This movement and complex formation with Mgl ...201121847100
Identification and Localization of Myxococcus xanthus Porins and Lipoproteins.Myxococcus xanthus DK1622 contains inner (IM) and outer membranes (OM) separated by a peptidoglycan layer. Integral membrane, ß-barrel proteins are found exclusively in the OM where they form pores allowing the passage of nutrients, waste products and signals. One porin, Oar, is required for intercellular communication of the C-signal. An oar mutant produces CsgA but is unable to ripple or stimulate csgA mutants to develop suggesting that it is the channel for C-signaling. Six prediction program ...201122132103
spore formation in myxococcus xanthus is tied to cytoskeleton functions and polysaccharide spore coat deposition.myxococcus xanthus is a gram-negative bacterium that differentiates into environmentally resistant spores. spore differentiation involves septation-independent remodelling of the rod-shaped vegetative cell into a spherical spore and deposition of a thick and compact spore coat outside of the outer membrane. our analyses suggest that spore coat polysaccharides are exported to the cell surface by the exo outer membrane polysaccharide export/polysaccharide co-polymerase 2a (opx/pcp-2a) machinery. c ...201122188356
exopolysaccharide-independent social motility of myxococcus xanthus.social motility (s motility), the coordinated movement of large cell groups on agar surfaces, of myxococcus xanthus requires type iv pili (tfp) and exopolysaccharides (eps). previous models proposed that this behavior, which only occurred within cell groups, requires cycles of tfp extension and retraction triggered by the close interaction of tfp with eps. however, the curious observation that m. xanthus can perform tfp-dependent motility at a single-cell level when placed onto polystyrene surfa ...201121245931
myxobacteria gliding motility requires cytoskeleton rotation powered by proton motive force.myxococcus xanthus is a gram-negative bacterium that glides over surfaces without the aid of flagella. two motility systems are used for locomotion: social-motility, powered by the retraction of type iv pili, and adventurous (a)-motility, powered by unknown mechanism(s). we have shown that agmu, an a-motility protein, is part of a multiprotein complex that spans the inner membrane and periplasm of m. xanthus. in this paper, we present evidence that periplasmic agmu decorates a looped continuous ...201121248229
combinatorial regulation of fmgd by mrpc2 and frua during myxococcus xanthus development.upon starvation, a dense population of rod-shaped myxococcus xanthus bacteria coordinate their movements to construct mounds in which some of the cells differentiate to spherical spores. during this process of fruiting body formation, short-range c-signaling between cells regulates their movements and the expression of genes important for sporulation. c-signaling activates frua, a transcription factor that binds cooperatively with another transcription factor, mrpc2, upstream of the fmga and fmg ...201121257775
structure-activity relationships of diphenyl-ether as protoporphyrinogen oxidase inhibitors: insights from computational simulations.protoporphyrinogen oxidase (ppo, ec 1.3.3.4), which has been identified as a significant target for a great family of herbicides with diverse chemical structures, is the last common enzyme responsible for the seventh step in the biosynthetic pathway to heme and chlorophyll. among the existing ppo inhibitors, diphenyl-ether is the first commercial family of ppo inhibitors and used as agriculture herbicides for decades. most importantly, diphenyl-ether inhibitors have been found recently to posses ...201121259066
enzymatic and mutational analyses of a class ii 3',5'-cyclic nucleotide phosphodiesterase, pdee, from myxococcus xanthus.myxococcus xanthus pdee, an enzyme homologous to class ii 3',5'-cyclic nucleotide phosphodiesterases, hydrolyzed cyclic amp (camp) and cgmp with k(m) values of 12 µm and 25 µm, respectively. a pdee mutant exhibited delays in fruiting body and spore formation compared with the wild type when cultured on starvation medium.201121317337
natural transformation of myxococcus xanthus.myxococcus xanthus belongs to the delta class of the proteobacteria and is notable for its complex life-style with social behaviors and relatively large genome. although previous observations have suggested the existence of horizontal gene transfer in m. xanthus, its ability to take up exogenous dna via natural transformation has not been experimentally demonstrated. in this study, we achieved natural transformation in m. xanthus using the autonomously replicating myxobacterial plasmid pzjy41 as ...201121378184
enzymatic and functional analysis of a protein phosphatase, pph3, from myxococcus xanthus.a protein phosphatase, designated pph3, from myxococcus xanthus showed the enzymatic characteristics of pp2c-type serine/threonine protein phosphatases, which are metal ion-dependent, okadaic acid-insensitive protein phosphatases. the pph3 mutant under starvation conditions formed immature fruiting bodies and reduced sporulation.201121398555
bacm, an n-terminally processed bactofilin of myxococcus xanthus, is crucial for proper cell shape.bactofilins are fibre-forming bacterial cytoskeletal proteins. here, we report the structural and biochemical characterization of mxan_7475 (bacm), one of the four bactofilins of myxococcus xanthus. absence of bacm leads to a characteristic 'crooked' cell morphology and an increased sensitivity to antibiotics targeting cell wall biosynthesis. the absence of the other three bactofilins mxan_4637-4635 (bacn-p) has no obvious phenotype. in m. xanthus, bacm exists as a 150-amino-acid full-length ver ...201121414039
statistical image analysis reveals features affecting fates of myxococcus xanthus developmental aggregates.starving myxococcus xanthus bacteria use their motility systems to self-organize into multicellular fruiting bodies, large mounds in which cells differentiate into metabolically inert spores. despite the identification of the genetic pathways required for aggregation and the use of microcinematography to observe aggregation dynamics in wt and mutant strains, a mechanistic understanding of aggregation is still incomplete. for example, it is not clear why some of the initial aggregates mature into ...201121436028
combinatorial regulation by mrpc2 and frua involves three sites in the fmge promoter region during myxococcus xanthus development.starvation causes cells in a dense population of myxococcus xanthus to change their gliding movements and construct mounds. short-range c-signaling between rod-shaped cells within mounds induces gene expression that promotes differentiation into spherical spores. several c-signal-dependent genes have been shown to be regulated by cooperative binding of two transcription factors to the promoter region. these frua- and mrpc2-regulated genes (designated fmg) each exhibit a different arrangement of ...201121441502
evidence that a chaperone-usher-like pathway of myxococcus xanthus functions in spore coat formation.many bacteria use the chaperone-usher (cu) secretion pathway to assemble on their surfaces typical or atypical fimbrial organelles. four consecutive genes of myxococcus xanthus dk1622, mxan3885-3882, were predicted to constitute an operon encoding a cu-like system involved in the assembly of the spore coat; however, experimental evidence supporting this hypothesis was lacking. in this study, co-transcription of mxan3885-3883 was verified, and we found that this operon was expressed 12-15 h after ...201121454366
study of elastic collisions of myxococcus xanthus in swarms.in very low density situations where a single myxobacterial cell is isolated from direct contact with other cells, the slime capsule interaction with the substrate or slime tracks on the substrate produce a viscous drag that results in a smooth gliding motion. viscoelastic interactions of myxobacteria cells in a low-density domain close to the edge of a swarm are studied using a combination of a cell-based three-dimensional computational model and cell-tracking experiments. the model takes into ...201121471636
from the cover: motor-driven intracellular transport powers bacterial gliding motility.protein-directed intracellular transport has not been observed in bacteria despite the existence of dynamic protein localization and a complex cytoskeleton. however, protein trafficking has clear potential uses for important cellular processes such as growth, development, chromosome segregation, and motility. conflicting models have been proposed to explain myxococcus xanthus motility on solid surfaces, some favoring secretion engines at the rear of cells and others evoking an unknown class of m ...201121482768
alanine 32 in pila is important for pila stability and type iv pili function in myxococcus xanthus.type iv pili (tfp) are membrane anchored filaments with a number of important biological functions. in the model organism myxococcus xanthus, tfp act as molecular engines that power social (s)-motility through cycles of extension and retraction. tfp filament consists of several thousand copies of a protein called either pila or pilin. pila contains an n-terminal α-helix essential for tfp assembly and a c-terminal globular domain important for its activity. the role of the pila sequence and its s ...201121493683
light-dependent gene regulation by a coenzyme b12-based photoreceptor.cobalamin (b(12)) typically functions as an enzyme cofactor but can also regulate gene expression via rna-based riboswitches. b(12)-directed gene regulatory mechanisms via protein factors have, however, remained elusive. recently, we reported down-regulation of a light-inducible promoter in the bacterium myxococcus xanthus by two paralogous transcriptional repressors, of which one, carh, but not the other, cara, absolutely requires b(12) for activity even though both have a canonical b(12)-bindi ...201121502508
directional intracellular trafficking in bacteria. 201121508322
small acid-soluble proteins with intrinsic disorder are required for uv resistance in myxococcus xanthus spores.bacterial sporulation in gram-positive bacteria results in small acid-soluble proteins called sasps that bind to dna and prevent the damaging effects of uv radiation. orthologs of bacillus subtilis genes encoding sasps can be found in many sporulating and nonsporulating bacteria, but they are noticeably absent from spore-forming, gram-negative myxococcus xanthus. this is despite the fact that m. xanthus can form uv-resistant spores. here we report evidence that m. xanthus produces its own unique ...201121515768
chemotactic predator-prey dynamics.a discrete chemotactic predator-prey model is proposed in which the prey secrets a diffusing chemical which is sensed by the predator and vice versa. two dynamical states corresponding to catching and escaping are identified and it is shown that steady hunting is unstable. for the escape process, the predator-prey distance is diffusive for short times but exhibits a transient subdiffusive behavior which scales as a power law t^{1/3} with time t and ultimately crosses over to diffusion again. thi ...201121517532
investigation of cytochromes p450 in myxobacteria: excavation of cytochromes p450 from the genome of sorangium cellulosum so ce56.the exploitation of cytochromes p450 for novel biotechnological application and for the investigation of their physiological function is of great scientific interest in this post genomic era, where an extraordinary biodiversity of p450 genes has been derived from all forms of life. the study of p450s in the myxobacterium sorangium cellulosum strain so ce56, the producer of novel secondary metabolites of pharmaceutical interest is the research topic, in which we were engaged since the beginning o ...201121521637
experimental evolution of selfish policing in social bacteria.cooperative organisms evolve within socially diverse populations. in populations harboring both cooperators and cheaters, cooperators might adapt by evolving novel interactions with either social type or both. diverse animal traits suppress selfish behaviors when cooperation is important for fitness, but the potential for prokaryotes to evolve such traits is unclear. we allowed a strain of the bacterium myxococcus xanthus that is proficient at cooperative fruiting body development to evolve whil ...201121531905
in vivo fluorescence imaging of exogenous enzyme activity in the gastrointestinal tract.exogenous enzymes are administered orally to treat several diseases, such as pancreatic insufficiency and lactose intolerance. due to the proteinaceous nature of enzymes, they are subject to inactivation and/or digestion in the gastrointestinal (gi) tract. here we describe a convenient fluorescence-based assay to monitor the activity of therapeutic enzymes in real time in vivo in the gi tract. to establish the proof of principle, the assay was applied to proline-specific endopeptidases (peps), a ...201121576491
identification and characterization of the althiomycin biosynthetic gene cluster in myxococcus xanthus dk897. 201121626639
heterologous protein transfer within structured myxobacteria biofilms.microbial biofilms represent heterogeneous populations of cells that form intimate contacts. within these populations cells communicate, cooperate and compete. myxobacteria are noted for their complex social interactions, including gliding motility and lipoprotein exchange. here, we investigated cis protein sequence and cellular behaviour requirements for lipoprotein transfer between myxococcus xanthus cells. specifically, an outer membrane (om) type ii signal sequence (ss) fused to the heterolo ...201121635581
discovery of a gene involved in a third bacterial protoporphyrinogen oxidase activity through comparative genomic analysis and functional complementation.tetrapyrroles are ubiquitous molecules in nearly all living organisms. heme, an iron containing tetrapyrrole, is widely distributed in nature including most characterized aerobic and facultative bacteria. a large majority of bacteria that contain heme possess the ability to synthesize it. despite this capability, and the fact that the biosynthetic pathway has been well studied, enzymes catalyzing at least three steps have remained "missing" in many bacteria. in the current work we have employed ...201121642412
close encounters: contact-dependent interactions in bacteria.bacterial cells interact extensively within and between species. these interactions can be divided into those that rely on diffusible factors and those that depend on direct cell-to-cell contacts. an example of a contact-dependent interaction is the transfer of lipoproteins between myxococcus xanthus cells that leads to transient stimulation of motility in certain motility mutants. in this issue of molecular microbiology, wei et al. (2011) provide mechanistic insights into this contact-dependent ...201121651624
core from myxococcus xanthus is a copper-dependent rna polymerase sigma factor.the dual toxicity/essentiality of copper forces cells to maintain a tightly regulated homeostasis for this metal in all living organisms, from bacteria to humans. consequently, many genes have previously been reported to participate in copper detoxification in bacteria. myxococcus xanthus, a prokaryote, encodes many proteins involved in copper homeostasis that are differentially regulated by this metal. a σ factor of the ecf (extracytoplasmic function) family, core, has been found to regulate th ...201121655090
a cascade of coregulating enhancer binding proteins initiates and propagates a multicellular developmental program.the signal transduction networks that initiate multicellular development in bacteria remain largely undefined. here, we report that myxococcus xanthus regulates entry into its multicellular developmental program using a novel strategy: a cascade of transcriptional activators known as enhancer binding proteins (ebps). the ebps in the cascade function in sequential stages of early development, and several lines of evidence indicate that the cascade is propagated when ebps that function at one stag ...201121670274
fatty acyl-amp ligase involvement in the production of alkylresorcylic acid by a myxococcus xanthus type iii polyketide synthase.fatty acyl-amp ligases (faals) activate fatty acids as acyladenylates, and subsequently catalyze their transfer onto the acyl carrier proteins (acps) of polyketide synthases (pkss) or nonribosomal peptide synthetases to produce lipidic metabolites. myxococcus xanthus contains a polyketide biosynthesis gene cluster in which putative faal (ftpd) and acp (ftpc) genes are located close to a type iii pks (ftpa) gene. here we describe the characterization of these three proteins in vitro. ftpd adenyla ...201121815236
experimentally guided computational model discovers important elements for social behavior in myxobacteria.identifying essential factors in cellular interactions and organized movement of cells is important in predicting behavioral phenotypes exhibited by many bacterial cells. we chose to study myxococcus xanthus, a soil bacterium whose individual cell behavior changes while in groups, leading to spontaneous formation of aggregation center during the early stage of fruiting body development. in this paper, we develop a cell-based computational model that solely relies on experimentally determined par ...201121811570
crds and crda comprise a two-component system that is cooperatively regulated by the che3 chemosensory system in myxococcus xanthus.abstract myxococcus xanthus serves as a model organism for development and complex signal transduction. regulation of developmental aggregation and sporulation is controlled, in part, by the che3 chemosensory system. the che3 pathway consists of homologs to two methyl-accepting chemotaxis proteins (mcps), chea, chew, cheb, and cher but not chey. instead, the output for che3 is the ntrc homolog crda, which functions to regulate developmental gene expression. in this paper we have identified an ad ...201121810965
myxobacterial vesicles death at a distance?outer membrane vesicles (omvs) are produced from the outer membrane (om) of myxobacterial cells and are found in large quantities within myxobacterial biofilms. it has been proposed that omvs are involved in several of the social behaviors exhibited by the myxobacteria, including motility and predation. proteomic data suggest that specific proteins are either selectively incorporated into or excluded from myxobacterial omvs, as observed for omvs of other organisms. hydrolases are found in large ...201121807244
quantifying aggregation dynamics during myxococcus xanthus development.under starvation conditions, a swarm of myxococcus xanthus cells will undergo development, a multicellular process culminating in the formation of many aggregates called fruiting bodies, each of which contains up to 100,000 spores. the mechanics of symmetry-breaking and the self-organization of cells into fruiting bodies is an active area of research. here we use microcinematography and automated image processing to quantify several transient features of developmental dynamics. an analysis of ex ...201121784940
antibiotic production by myxobacteria plays a role in predation.myxobacteria are predatory and are prolific producers of secondary metabolites. here, we tested a hypothesized role that secondary metabolite antibiotics function as weapons in predation. to test this, a myxococcus xanthus ?ta1 mutant, blocked in antibiotic ta (myxovirescin) production, was constructed. against escherichia coli this ta(-) mutant was defective in producing a zone of inhibition (zoi). this shows that ta is the major m. xanthus diffusible antibacterial agent against e. coli. corres ...201121764930
endemic social diversity within natural kin groups of a cooperative bacterium.the spatial structure of genetic diversity underlying social variation is a critical determinant of how cooperation and conflict evolve. here we investigated whether natural social groups of the cooperative soil bacterium myxococcus xanthus harbor internal genetic and phenotypic variation and thus the potential for social conflict between interacting cells. ten m. xanthus fruiting bodies isolated from soil were surveyed for variation in multiple social phenotypes and genetic loci, and patterns o ...201121690390
role of phase variation in the resistance of myxococcus xanthus fruiting bodies to caenorhabditis elegans predation.the phenomenon of phase variation between yellow and tan forms of myxococcus xanthus has been recognized for several decades, but it is not known what role this variation may play in the ecology of myxobacteria. we confirm an earlier report that tan variants are disproportionately more numerous in the resulting spore population of a m. xanthus fruiting body compared to the number of tan vegetative cells that contributed to fruiting body formation. however, we found that tan cells may not require ...201121821771
global analysis of phase variation in myxococcus xanthus.myxococcus xanthus can vary its phenotype or 'phase' to produce colonies that contain predominantly yellow or tan cells that differ greatly in their abilities to swarm, survive and develop. yellow variants are proficient at swarming (++) and tend to lyse in liquid during stationary phase. in contrast, tan variants are deficient in swarming (+) and persist beyond stationary phase. the phenotypes and transcriptomes of yellow and tan variants were compared with mutants affected in phase variation. ...201121722202
a myxococcus xanthus bacterial tyrosine kinase, btka, is required for the formation of mature spores.a myxococcus xanthus cytoplasmic bacterial tyrosine kinase, btka, showed phosphorylation activity in the presence of exo. phosphorylated btka was expressed late after starvation induction and early after glycerol induction. btka mutant was unable to complete maturation to heat- and sonication-resistant spores under both starvation- and glycerol-induced developmental conditions.201121840977
The Myxococcus xanthus Spore Cuticula Protein C Is a Fragment of FibA, an Extracellular Metalloprotease Produced Exclusively in Aggregated Cells.Myxococcus xanthus is a soil bacterium with a complex life cycle involving distinct cell fates, including production of environmentally resistant spores to withstand periods of nutrient limitation. Spores are surrounded by an apparently self-assembling cuticula containing at least Proteins S and C; the gene encoding Protein C is unknown. During analyses of cell heterogeneity in M. xanthus, we observed that Protein C accumulated exclusively in cells found in aggregates. Using mass spectrometry an ...201122174937
characterization of the partitioning system of myxococcus plasmid pmf1.pmf1 is the only autonomously replicating plasmid that has been recently identified in myxobacteria. this study characterized the partitioning (par) system of this plasmid. the fragment that significantly increased the retaining stability of plasmids in myxococcus cells in the absence of selective antibiotics contained three open reading frames (orfs) pmf1.21-pmf1.23 (parcab). the pmf1.22 orf (para) is homologous to members of the para atpase family, with the highest similarity (56%) to the sphi ...201122174771
genome sequence of the halotolerant marine bacterium myxococcus fulvus hw-1.myxococcus fulvus hw-1 (atcc baa-855) is a halotolerant marine myxobacterium. this strain exhibits complex social behaviors in the presence of low concentrations of seawater but adopts an asocial living pattern under oceanic conditions. the whole genome of m. fulvus hw-1 will enable us to further investigate the details of its evolution.201121868801
three-dimensional obstacles for bacterial surface motility.twitching motility enables bacteria to move over surfaces using type iv pili as grappling hooks. here it is shown that the motility of the round neisseria gonorrhoeae as well as of rod-shaped myxococcus xanthus is guided by elevations with dimension and depth corresponding to the size of the bacteria.201122183854
myxococcus xanthus induces actinorhodin overproduction and aerial mycelium formation by streptomyces coelicolor.interaction of the predatory myxobacterium myxococcus xanthus with the non-motile, antibiotic producer streptomyces coelicolor was examined using a variety of experimental approaches. myxococcus xanthus cells prey on s. coelicolor, forming streams of ordered cells that lyse the s. coelicolor hyphae in the contact area between the two colonies. the interaction increases actinorhodin production by s. coelicolor up to 20-fold and triggers aerial mycelium production. other bacteria are also able to ...201021342463
improving cellular properties for genetic manipulation by dispersed growing mutagenesis in myxococcus fulvus hw-1.one of the key limitations to genetic manipulation in myxobacteria is that the cells grow in clumps in liquid. a salt-tolerant strain hw-1 of myxococcus fulvus was treated with uv irradiation and produced a completely dispersedly growing mutant uv684. there were no significant differences between the parent hw-1 and the mutant uv684 in terms of salt-tolerant growth. the mutant uv684 and the parent strain had the similar abilities of the fruiting body formation and s motility. interestingly, the ...201019998037
glycine betaine biosynthesized from glycine provides an osmolyte for cell growth and spore germination during osmotic stress in myxococcus xanthus.glycine sarcosine methyltransferase (gsm) and sarcosine dimethylglycine methyltransferase (sdm) catalyze glycine betaine synthesis from glycine. disruption of the m. xanthus gsma (mxan 7068) or sdma (mxan 3190) gene, encoding gsm or sdm homologue proteins, respectively, generated mutants that exhibited a longer lag period of growth and delayed spore germination under osmostress.201020023011
extracellular biology of myxococcus xanthus.myxococcus xanthus has a lifecycle characterized by several social interactions. in the presence of prey, m. xanthus is a predator forming cooperatively feeding colonies, and in the absence of nutrients, m. xanthus cells interact to form multicellular, spore-filled fruiting bodies. formation of both cellular patterns depends on extracellular functions including the extracellular matrix and intercellular signals. interestingly, the formation of these patterns also depends on several activities th ...201019895646
identification of enhancer binding proteins important for myxococcus xanthus development.enhancer binding proteins (ebps) control the temporal expression of fruiting body development-associated genes in myxococcus xanthus. eleven previously uncharacterized ebp genes were inactivated. six ebp gene mutations produced minor but reproducible defects in fruiting body development. one ebp gene mutation that affected a-motility produced strong developmental defects.201019897655
estimation of protein and domain interactions in the switching motility system of myxococcus xanthus.the gram-negative myxobacterium myxococcus xanthus is equipped with an interesting motility system that allows it to reverse direction on average every 8 minutes by switching the construction of two motility engines at the ends of this rod-shaped bacterium. while the mechanisms responsible for timing and engine construction/deconstruction are relatively well understood, there are several competing hypotheses as to how they are coupled together. in this paper we examine the evidence for protein i ...201019908368
bacterial motility complexes require the actin-like protein, mreb and the ras homologue, mgla.gliding motility in the bacterium myxococcus xanthus uses two motility engines: s-motility powered by type-iv pili and a-motility powered by uncharacterized motor proteins and focal adhesion complexes. in this paper, we identified mreb, an actin-like protein, and mgla, a small gtpase of the ras superfamily, as essential for both motility systems. a22, an inhibitor of mreb cytoskeleton assembly, reversibly inhibited s- and a-motility, causing rapid dispersal of s- and a-motility protein clusters, ...201019959988
myxococcus xanthus viability depends on groel supplied by either of two genes, but the paralogs have different functions during heat shock, predation, and development.myxococcus xanthus dk1622 contains two paralogous groel gene loci that possess both different sequences and different organizations within the genome. deletion of either one of these two genes alone does not affect cell viability. however, deletion of both groel genes results in cell death unless a complemented groel1 or groel2 gene is present. the groel1 gene was determined to be essential for cell survival under heat shock conditions; a strain with mutant groel2 caused cells to be more sensiti ...201020139189
spatial simulations of myxobacterial development.many bacteria exhibit multicellular behaviour, with individuals within a colony coordinating their actions for communal benefit. one example of complex multicellular phenotypes is myxobacterial fruiting body formation, where thousands of cells aggregate into large three-dimensional structures, within which sporulation occurs. here we describe a novel theoretical model, which uses monte carlo dynamics to simulate and explain multicellular development. the model captures multiple behaviours observ ...201020195493
localization of mgla, an essential gliding motility protein in myxococcus xanthus.mgla, a 22-kda protein related to monomeric gtpases, is required for the normal operation of the a (adventurous) and s (social) motility and for multicellular development of myxococcus xanthus. to determine how mgla controls a- and s-motility, mgla was assayed biochemically and its cellular location was determined. his-tagged mgla hydrolyzed gtp slowly in vitro at a rate nearly identical to that of ras showing that mgla has gtpase activity. immunofluorescence microscopy of fixed cells from liqui ...201020196075
heterologous expression of the oxytetracycline biosynthetic pathway in myxococcus xanthus.new natural products for drug discovery may be accessed by heterologous expression of bacterial biosynthetic pathways in metagenomic dna libraries. however, a "universal" host is needed for this experiment. herein, we show that myxococcus xanthus is a potential "universal" host for heterologous expression of polyketide biosynthetic gene clusters.201020208031
[construction and application of plasmid pzcy11 for analyzing gene functions and expressions in myxococcus].to construct a plasmid for analyzing gene functions and expressions and to study the mxan1334 gene in myxococcus xanthus with the plasmid.201020344937
cdnl, a member of the large card-like family of bacterial proteins, is vital for myxococcus xanthus and differs functionally from the global transcriptional regulator card.card, a global transcriptional regulator in myxococcus xanthus, interacts with carg via cardnter, its n-terminal domain, and with dna via a eukaryotic hmga-type c-terminal domain. genomic analysis reveals a large number of standalone proteins resembling cardnter. these constitute, together with the rna polymerase (rnap) interacting domain, rid, of transcription-repair coupling factors, the card_trcf protein family. we show that one such cardnter-like protein, m. xanthus cdnl, cannot functionally ...201020371514
bioconservation of deteriorated monumental calcarenite stone and identification of bacteria with carbonatogenic activity.the deterioration of the stone built and sculptural heritage has prompted the search and development of novel consolidation/protection treatments that can overcome the limitations of traditional ones. attention has been drawn to bioconservation, particularly bacterial carbonatogenesis (i.e. bacterially induced calcium carbonate precipitation), as a new environmentally friendly effective conservation strategy, especially suitable for carbonate stones. here, we study the effects of an in situ bact ...201020386895
bacterial community dynamics during the application of a myxococcus xanthus-inoculated culture medium used for consolidation of ornamental limestone.in this study, we investigated under laboratory conditions the bacterial communities inhabiting quarry and decayed ornamental carbonate stones before and after the application of a myxococcus xanthus-inoculated culture medium used for consolidation of the stones. the dynamics of the community structure and the prevalence of the inoculated bacterium, m. xanthus, were monitored during the time course of the consolidation treatment (30 days). for this purpose, we selected a molecular strategy combi ...201020393845
a bacterial antirepressor with sh3 domain topology mimics operator dna in sequestering the repressor dna recognition helix.direct targeting of critical dna-binding elements of a repressor by its cognate antirepressor is an effective means to sequester the repressor and remove a transcription initiation block. structural descriptions for this, though often proposed for bacterial and phage repressor-antirepressor systems, are unavailable. here, we describe the structural and functional basis of how the myxococcus xanthus cars antirepressor recognizes and neutralizes its cognate repressors to turn on a photo-inducible ...201020410074
hdsp, a horizontally transferred gene required for social behavior and halotolerance in salt-tolerant myxococcus fulvus hw-1.myxococcus fulvus hw-1, a salt-tolerant bacterial strain, which was isolated from a coastal environment, changes its behavior with different salinities. to study the relationship between behavioral shifts and the adaption to oceanic conditions, the hw-1 strain was randomly mutagenized using transposon insertion, producing a dispersed-growing mutant, designated ylh0401. the mutant did not develop fruiting bodies and myxospores, was deficient in s-motility, produced less extracellular matrix and w ...201020410933
global transcriptome analysis of spore formation in myxococcus xanthus reveals a locus necessary for cell differentiation.myxococcus xanthus is a gram negative bacterium that can differentiate into metabolically quiescent, environmentally resistant spores. little is known about the mechanisms involved in differentiation in part because sporulation is normally initiated at the culmination of a complex starvation-induced developmental program and only inside multicellular fruiting bodies. to obtain a broad overview of the sporulation process and to identify novel genes necessary for differentiation, we instead perfor ...201020420673
pila localization affects extracellular polysaccharide production and fruiting body formation in myxococcus xanthus.myxococcus xanthus is a gram-negative bacterium capable of complex developmental processes involving vegetative swarming and fruiting body formation. social (s-) gliding motility, one of the two motility systems used by m. xanthus, requires at least two cell surface structures: type iv pili (tfp) and extracellular polysaccharides (eps). extended tfp that are composed of thousands of copies of pila retract upon binding to eps and thereby pull the cell forward. tfp also act as external sensor to r ...201020444090
a multi-protein complex from myxococcus xanthus required for bacterial gliding motility.myxococcus xanthus moves by gliding motility powered by type iv pili (s-motility) and a second motility system, a-motility, whose mechanism remains elusive despite the identification of approximately 40 a-motility genes. in this study, we used biochemistry and cell biology analyses to identify multi-protein complexes associated with a-motility. previously, we showed that the n-terminal domain of frzcd, the receptor for the frizzy chemosensory pathway, interacts with two a-motility proteins, aglz ...201020487265
developmental expression of dnaa is required for sporulation and timing of fruiting body formation in myxococcus xanthus.inhibition of dna replication within the first 6 h of development results in a block in the developmental programme in the social soil bacterium myxococcus xanthus. we have interpreted these data to imply that m. xanthus requires a new round of dna replication early in the developmental programme. to further understand the role of dna replication during development in m. xanthus we focused on the regulation of dnaa which encodes the initiator protein of dna replication. in this work, we demonstr ...201020487266
adaptive evolution of an srna that controls myxococcus development.small rna (srna) molecules regulate a vast array of processes in biology, but evidence for adaptive evolution of srna sequences has been indirect. here, we identify an srna, pxr, that negatively regulates fruiting body development in myxococcus xanthus. we further show that a spontaneous evolutionary mutation in pxr abolished its regulatory function and thereby adaptively restored developmental proficiency to a socially defective m. xanthus cheater. in wild-type m. xanthus, development is initia ...201020489016
natural variation in developmental life-history traits of the bacterium myxococcus xanthus.the soil bacterium myxococcus xanthus is a model for the study of cooperative microbial behaviours such as social motility and fruiting body formation. several m. xanthus developmental traits that are frequently quantified for laboratory strains are likely to be significant components of fitness in natural populations, yet little is known about the degree to which such traits vary in the wild and may therefore be subject to natural selection. here, we have tested whether several key m. xanthus d ...201020491924
gliding motility revisited: how do the myxobacteria move without flagella?in bacteria, motility is important for a wide variety of biological functions such as virulence, fruiting body formation, and biofilm formation. while most bacteria move by using specialized appendages, usually external or periplasmic flagella, some bacteria use other mechanisms for their movements that are less well characterized. these mechanisms do not always exhibit obvious motility structures. myxococcus xanthus is a motile bacterium that does not produce flagella but glides slowly over sol ...201020508248
phosphorylation and dephosphorylation among dif chemosensory proteins essential for exopolysaccharide regulation in myxococcus xanthus.myxococcus xanthus social gliding motility, which is powered by type iv pili, requires the presence of exopolysaccharides (eps) on the cell surface. the dif chemosensory system is essential for the regulation of eps production. it was demonstrated previously that difa (methyl-accepting chemotaxis protein [mcp]-like), difc (chew-like), and dife (chea-like) stimulate whereas difd (chey-like) and difg (chec-like) inhibit eps production. difd was found not to function downstream of dife in eps regul ...201020543066
regulation of dynamic polarity switching in bacteria by a ras-like g-protein and its cognate gap.the rod-shaped cells of the bacterium myxococcus xanthus move uni-directionally and occasionally undergo reversals during which the leading/lagging polarity axis is inverted. cellular reversals depend on pole-to-pole relocation of motility proteins that localize to the cell poles between reversals. we show that mgla is a ras-like g-protein and acts as a nucleotide-dependent molecular switch to regulate motility and that mglb represents a novel gtpase-activating protein (gap) family and is the co ...201020543819
the regulatory action of the myxobacterial card/carg complex: a bacterial enhanceosome?a global regulatory complex made up of two unconventional transcriptional factors, card and carg, is implicated in the control of various processes in myxococcus xanthus, a gram-negative bacterium that serves as a prokaryotic model system for multicellular development and the response to blue light. card has a unique two-domain architecture composed of: (1) a c-terminal dna-binding domain that resembles eukaryotic high mobility group a (hmga) proteins, which are relatively abundant, nonhistone c ...201020561058
differential regulation of six heavy metal efflux systems in the response of myxococcus xanthus to copper.myxococcus xanthus has to cope with changes in its environment during growth and development. among these factors, the concentration of copper is crucial due to the essential toxic effect of this metal, which forces the cells to maintain a tight homeostasis. the m. xanthus copper response is more complex than that in other bacteria, which is reflected by the different copper sensitivities of growing and developing cells. in the present study, the participation in copper homeostasis of six heavy ...201020562277
the phosphatomes of the multicellular myxobacteria myxococcus xanthus and sorangium cellulosum in comparison with other prokaryotic genomes.analysis of the complete genomes from the multicellular myxobacteria myxococcus xanthus and sorangium cellulosum identified the highest number of eukaryotic-like protein kinases (elks) compared to all other genomes analyzed. high numbers of protein phosphatases (pps) could therefore be anticipated, as reversible protein phosphorylation is a major regulation mechanism of fundamental biological processes.201020567509
a generalization of hamilton's rule for the evolution of microbial cooperation.hamilton's rule states that cooperation will evolve if the fitness cost to actors is less than the benefit to recipients multiplied by their genetic relatedness. this rule makes many simplifying assumptions, however, and does not accurately describe social evolution in organisms such as microbes where selection is both strong and nonadditive. we derived a generalization of hamilton's rule and measured its parameters in myxococcus xanthus bacteria. nonadditivity made cooperative sporulation remar ...201020576891
developments in defining dif. 201020601469
cell polarity/motility in bacteria: closer to eukaryotes than expected? 201020648047
3'-5' trnahis guanylyltransferase in bacteria.the identity of the histidine specific transfer rna (trna(his)) is largely determined by a unique guanosine residue at position -1. in eukaryotes and archaea, the trna(his) guanylyltransferase (thg1) catalyzes 3'-5' addition of g to the 5'-terminus of trna(his). here, we show that thg1 also occurs in bacteria. we demonstrate in vitro thg1 activity for recombinant enzymes from the two bacteria bacillus thuringiensis and myxococcus xanthus and provide a closer investigation of several archaeal thg ...201020650272
mglb fills a gap in bacterial polarity and motility. 201020652017
a bacterial ras-like small gtp-binding protein and its cognate gap establish a dynamic spatial polarity axis to control directed motility.regulated cell polarity is central to many cellular processes. we investigated the mechanisms that govern the rapid switching of cell polarity (reversals) during motility of the bacterium myxococcus xanthus. cellular reversals are mediated by pole-to-pole oscillations of motility proteins and the frequency of the oscillations is under the control of the frz chemosensory system. however, the molecular mechanism that creates dynamic polarity remained to be characterized. in this work, we establish ...201020652021
expression and physiological role of three myxococcus xanthus copper-dependent p1b-type atpases during bacterial growth and development.myxococcus xanthus is a soil-dwelling bacterium that exhibits a complex life cycle comprising social behavior, morphogenesis, and differentiation. in order to successfully complete this life cycle, cells have to cope with changes in their environment, among which the presence of copper is remarkable. copper is an essential transition metal for life, but an excess of copper provokes cellular damage by oxidative stress. this dual effect forces the cells to maintain a tight homeostasis. m. xanthus ...201020656859
profiling the outer membrane proteome during growth and development of the social bacterium myxococcus xanthus by selective biotinylation and analyses of outer membrane vesicles.social behavior in the bacterium myxococcus xanthus relies on contact-dependent activities involving cell-cell and cell-substratum interactions. to identify outer membrane proteins that have a role in these activities, we profiled the outer membrane proteome of growing and starving cells using two strategies. first, outer membrane proteins were enriched by biotinylation of intact cells using the reagent nhs (n-hydroxysuccinimide)-peo(12) (polyethylene oxide)-biotin with subsequent membrane solub ...201020687614
recording multicellular behavior in myxococcus xanthus biofilms using time-lapse microcinematography.a swarm of the delta-proteobacterium myxococcus xanthus contains millions of cells that act as a collective, coordinating movement through a series of signals to create complex, dynamic patterns as a response to environmental cues. these patterns are self-organizing and emergent; they cannot be predicted by observing the behavior of the individual cells. using a time-lapse microcinematography tracking assay, we identified a distinct emergent pattern in m. xanthus called chemotaxis, defined as th ...201020729807
comparative analysis of myxococcus predation on soil bacteria.predator-prey relationships among prokaryotes have received little attention but are likely to be important determinants of the composition, structure, and dynamics of microbial communities. many species of the soil-dwelling myxobacteria are predators of other microbes, but their predation range is poorly characterized. to better understand the predatory capabilities of myxobacteria in nature, we analyzed the predation performance of numerous myxococcus isolates across 12 diverse species of bact ...201020802074
kinetic and structural characterization of bacterial glutaminyl cyclases from zymomonas mobilis and myxococcus xanthus.although enzymes responsible for the cyclization of amino-terminal glutamine residues are present in both plant and mammal species, none have yet been characterized in bacteria. based on low sequence homologies to plant glutaminyl cyclases (qcs), we cloned the coding sequences of putative microbial qcs from zymomonas mobilis (zmqc) and myxococcus xanthus (mxqc). the two recombinant enzymes exhibited distinct qc activity, with specificity constants k(cat)/k(m) of 1.47±0.33 mm⁻¹ s⁻¹ (zmqc) and 142 ...201020868223
two-component systems and regulation of developmental progression in myxococcus xanthus.myxococcus xanthus is a prokaryotic model system for multicellular development and cell differentiation. two-component signal transduction genes are abundant in this organism and the majority is likely organized into complex signaling pathways. this chapter describes in vivo genetic and in vitro biochemical methods used to define signal transduction systems in m. xanthus. we also describe a series of phenotypic analyses utilized to define how a specific set of atypical histidine kinases (hks) in ...201020946852
comparative genomic analysis of fruiting body formation in myxococcales.genetic programs underlying multicellular morphogenesis and cellular differentiation are most often associated with eukaryotic organisms, but examples also exist in bacteria such as the formation of multicellular, spore-filled fruiting bodies in the order myxococcales. most members of the myxococcales undergo a multicellular developmental program culminating in the formation of spore-filled fruiting bodies in response to starvation. to gain insight into the evolutionary history of fruiting body ...201021037205
preparation, purification and characteristics of an aflatoxin degradation enzyme from myxococcus fulvus ansm068.to prepare, purify and characterize an extracellular enzyme from myxococcus fulvus ansm068, designated as myxobacteria aflatoxin degradation enzyme (made), which possesses degradation activity against aflatoxin b(1) (afb(1) ), g(1) (afg(1) ) and m(1) (afm(1) ) in solution.201021040271
impact of alternative electron acceptors on selenium(iv) reduction by anaeromyxobacter dehalogenans.the capability of anaeromyxobacter dehalogenans to reduce se(iv) to se(0) as a detoxification mechanism suggests a potential role of these ecologically important microorganisms in the biogeochemical cycling of selenium and the control of selenium contamination. however, the reduction of se(iv) by the energetically versatile a. dehalogenans could be hindered by its ability to use alternative electron acceptors, particularly fe(iii) and humic substances which are ubiquitous in the environment. ind ...201021041077
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