| growth medium-dependent regulation of myxococcus xanthus fatty acid content is controlled by the esg locus. | we compared the cellular fatty acid profiles of myxococcus xanthus cells grown in either a casitone-based complex medium or a chemically defined medium. the cells grown in the complex medium had a much higher content of the abundant branched-chain fatty acid iso-15:0 and several other branched-chain species. the higher branched-chain fatty acid content of the cells grown in the complex medium was dependent on the esg locus, which encodes the e1alpha and e1beta components of a branched-chain keto ... | 1998 | 9748468 |
| chemotaxis in a gliding bacterium. | myxococcus xanthus cells exhibit directed motility up phosphatidylethanolamine (pe) gradients, and we suggest that pe behaves as a chemoattractant. computer-assisted stop-motion digital microscopy was used to record cell movements in slide culture. pe decreased cellular reversal frequency with molecular specificity that was correlated with the fatty acid composition. synthetic dilauroyl (di c12:0) pe and dioleoyl (di c18:1 omega9c) pe suppressed direction reversals and stimulated movement up the ... | 1998 | 9751772 |
| a chaperone in the hsp70 family controls production of extracellular fibrils in myxococcus xanthus. | three independent tn5-lac insertions in the s1 locus of myxococcus xanthus inactivate the sglk gene, which is nonessential for growth but required for social motility and multicellular development. the sequence of sglk reveals that it encodes a homologue of the chaperone hsp70 (dnak). the sglk gene is cotranscribed with the upstream grps gene, which encodes a grpe homologue. unlike sglk, grps is not required for social motility or development. wild-type m. xanthus is encased in extracellular pol ... | 1998 | 9765567 |
| regulation of the expression of a gene encoding beta-endoglucanase secreted by myxococcus xanthus during growth: role of genes involved in developmental regulation. | an endoglucanase, cela, is secreted by myxococcus xanthus only during exponential growth. the production of this enzyme is decreased by mutations in 5 different genes (exc +/- phenotype), three of which correspond to asg genes which regulate the production of an early cell-to-cell signal in development. transcription of cela is decreased in two of these exc +/- mutants, whereas a post-transcriptional step is affected in two other exc- mutants. thus, asg genes, in addition to regulating the onset ... | 1998 | 9766232 |
| crl stimulates rpos activity during stationary phase. | rpos, an alternative primary sigma factor, has been shown to be regulated at multiple levels, including transcription, translation and protein stability. here, we present evidence that suggests that rpos is regulated at yet another level by the product of the crl gene. the crl gene was first thought to encode the major curlin subunit of curli (curli are surface structures that are induced by growth into stationary phase under conditions of low osmolarity and low temperature). later, it was deter ... | 1998 | 9767590 |
| the pilh gene encodes an abc transporter homologue required for type iv pilus biogenesis and social gliding motility in myxococcus xanthus. | type iv pilus genes have been shown to be required for social gliding motility in myxococcus xanthus. we report the discovery of four additional pil genes: pild, a homologue of type iv prepilin leader peptidases; and pilg, pilh and pili, which have no known homologues in other type iv pilus systems. pilh encodes an atp-binding cassette (abc) transporter homologue, the first such homologue to be required for the biogenesis of any bacterial pilus type. pilg and pili are co-transcribed with pilh an ... | 1998 | 9767592 |
| loss of social behaviors by myxococcus xanthus during evolution in an unstructured habitat. | social behaviors are often targets of natural selection among higher organisms, but quantifying the effects of such selection is difficult. we have used the bacterium myxococcus xanthus as a model system for studying the evolution of social interactions. changes in the social behaviors of 12 m. xanthus populations were quantified after 1,000 generations of evolution in a liquid habitat, in which interactions among individuals were continually hindered by shaking and low cell densities. derived l ... | 1998 | 9770494 |
| purification of and kinetic studies on a cloned protoporphyrinogen oxidase from the aerobic bacterium bacillus subtilis. | the previously cloned and expressed protoporphyrinogen oxidase from bacillus subtilis has been purified to homogeneity by ni2+ affinity chromatography using a his6 tag and characterized. the enzyme has a molecular weight of approximately 56,000 daltons, a pi of 7.5, a ph optimum (protoporphyrinogen) of 8.7, and a noncovalently bound flavine adenine dinucleotide cofactor. the michaelis constants (km) for protoporphyrinogen-ix, coproporphyrinogen-iii, and mesoporphyrinogen-ix are 1.0, 5.29, and 4. ... | 1998 | 9784236 |
| protein w, a spore-specific protein in myxococcus xanthus, formation of a large electron-dense particle in a spore. | the gene for the major spore-specific protein, termed protein w, was cloned, and it was found that protein w is composed of 426 amino acid residues including 31% charged (133 residues) and 39% hydrophobic (166 residues) amino acids. in the protein, a motif consisting of five amino acid residues [(v/l/i)-r-e-r-(v/l/i)] is repeated 28 times, and another motif [m-m-(p/g)-q-g] five times. protein w is synthesized during a very late stage of development, forming a single, large electron-dense particl ... | 1998 | 9786185 |
| regulation of motility behavior in myxococcus xanthus may require an extracytoplasmic-function sigma factor. | using interaction trap technology, we identified a putative extracytoplasmic-function (ecf) sigma factor (rpoe1) in myxococcus xanthus, a bacterium which has a complex life cycle that includes fruiting body formation. the first domain of the response regulator protein frzz, a component of the frz signal transduction system, was used as bait. although the rpoe1 protein displayed no interactions with control proteins presented as bait, a weak interaction with a second m. xanthus response regulator ... | 1998 | 9791117 |
| an abc transporter plays a developmental aggregation role in myxococcus xanthus. | myxococcus xanthus is a gram-negative bacterium which has a complex life cycle. autochemotaxis, a process whereby cells release a self-generated signaling molecule, may be the principal mechanism facilitating directed motility in both the vegetative swarming and developmental aggregation stages of this life cycle. the process requires the frz signal transduction system, including frzz, a protein which is composed of two domains, both showing homology to the enteric chemotaxis response regulator ... | 1998 | 9791121 |
| methylation of frzcd defines a discrete step in the developmental program of myxococcus xanthus. | myxococcus xanthus is a gram-negative soil bacterium which undergoes fruiting body formation during starvation. the frz signal transduction system has been found to play an important role in this process. frzcd, a methyl-accepting taxis protein homologue, shows modulated methylation during cellular aggregation, which is thought to be part of an adaptation response to an aggregation signal. in this study, we assayed frzcd methylation in many known and newly isolated mutants defective in fruiting ... | 1998 | 9791131 |
| the myxococcus xanthus lipopolysaccharide o-antigen is required for social motility and multicellular development. | the gliding bacterium myxococcus xanthus aggregates to form spore-filled fruiting bodies when nutrients are limiting. defective fruiting-body formation and sporulation result from mutations in the sasa locus, which encodes the wzm wzt wbga (formerly rfbabc) lipopolysaccharide (lps) o-antigen biosynthesis genes. mutants carrying these same sasa mutations are defective in social motility and form small glossy colonies. we report here that the developmental and motility phenotypes of four mutants e ... | 1998 | 9791173 |
| targeted mutagenesis of sigma54 activator proteins in myxococcus xanthus. | myxococcus xanthus dna segments related to the highly conserved central sequence of sigma54 activator proteins have been investigated. a genetic technique designed to inactivate a gene that encodes such an activator by inserting a plasmid-borne internal fragment of the putative gene has been tested. when the internal fragment inserted by homologous recombination into the corresponding chromosomal locus, the expected duplication of the gene was observed by southern hybridization. the single restr ... | 1998 | 9811647 |
| kinetic stabilisation of a modular protein by domain interactions. | protein s, a two-domain spore coat protein from myxococcus xanthus, is structurally related to eye-lens pr crystallins. no natural monomeric one-domain member of this protein superfamily is known. to determine the stability of the single domains and to explain the ubiquitous domain duplication, the isolated domains of protein s were constructed. the n-domain is thermodynamically more stable than the c-domain. in intact protein s, domain interactions lead to an apparent decrease in stability of t ... | 1998 | 9821973 |
| myxococcus xanthus sasn encodes a regulator that prevents developmental gene expression during growth. | myxococcus xanthus multicellular fruiting body development is initiated by nutrient limitation at high cell density. five clustered point mutations (sasb5, -14, -15, -16, and -17) can bypass the starvation and high-cell-density requirements for expression of the 4521 developmental reporter gene. these mutants express 4521 at high levels during growth and development in an asgb background, which is defective in generation of the cell density signal, a signal. a 1.3-kb region of the sasb locus clo ... | 1998 | 9829930 |
| identification and characterization of the myxococcus xanthus arge gene. | the chromosomal acetylornithine deacetylase (arge) gene of myxococcus xanthus was identified via homology to acetylornithine deacetylases from other bacterial species. a mutant carrying a disruption in arge was unable to grow on minimal media lacking supplemental arginine and formed fruiting bodies and spores in response to arginine starvation at high cell density. | 1998 | 9829957 |
| the strategy of myxococcus xanthus for group cooperative behavior. | new evidence has been presented from our laboratory that the gliding bacterium, myxococcus xanthus, does not home by chemotaxis toward a nutrient source. our experiments, those of others, and the theory presented here combine to suggest a model, called the 'pied piper' model. it hypothesizes a gene that has a high mutation rate forward and back (say something in excess 10(-4) mutations per cell generation) which leads to switching between two motility states. occasionally rare organisms become g ... | 1998 | 9850416 |
| inhibition of development of myxococcus xanthus by eukaryotic protein kinase inhibitors. | myxococcus xanthus is a social bacterium that lives in the soil and undergoes spectacular development to form multicellular fruiting bodies. it contains a large family of eukaryote-like serine/threonine protein kinases. we found that a number of inhibitors for eukaryotic protein serine, threonine, and tyrosine kinases could inhibit the development and sporulation of m. xanthus to various degrees. these results suggest that serine/threonine and tyrosine phosphorylation may be involved in developm ... | 1998 | 9851997 |
| the aada gene of plasmid r100 confers resistance to spectinomycin and streptomycin in myxococcus xanthus. | plasmids with the aada gene from plasmid r100, which confers resistance to the aminoglycosides spectinomycin and streptomycin in escherchia coli, can be introduced into wild-type myxococcus xanthus, strain dk1622, by electroporation. recombinant m. xanthus strains with integrated plasmids carrying the aada gene acquire resistance to high levels of these antibiotics. selection for aada in m. xanthus can be carried out independently of, or simultaneously with, selection for resistance to kanamycin ... | 1998 | 9852026 |
| the myxococcus xanthus pilq (sgla) gene encodes a secretin homolog required for type iv pilus biogenesis, social motility, and development. | the myxococcus xanthus sgla1 spontaneous mutation was originally isolated because it allowed dispersed cell growth in liquid yet retained the ability to form fruiting bodies. consequently, most of today's laboratory strains either contain the sgla1 mutation or were derived from strains that carry it. subsequent work showed that sgla was a gene for social gliding motility, a process which is mediated by type iv pili. here sgla is shown to map to the major pil cluster and to encode a 901-amino-aci ... | 1999 | 9864308 |
| the anti-sigma factors. | a mechanism for regulating gene expression at the level of transcription utilizes an antagonist of the sigma transcription factor known as the anti-sigma (anti-sigma) factor. the cytoplasmic class of anti-sigma factors has been well characterized. the class includes asia form bacteriophage t4, which inhibits escherichia coli sigma 70; flgm, present in both gram-positive and gram-negative bacteria, which inhibits the flagella sigma factor sigma 28; spoiiab, which inhibits the sporulation-specific ... | 1998 | 9891799 |
| cooperative organization of bacterial colonies: from genotype to morphotype. | in nature, bacteria must often cope with difficult environmental conditions. to do so they have developed sophisticated cooperative behavior and intricate communication pathways. utilizing these elements, motile microbial colonies frequently develop complex patterns in response to adverse growth conditions on hard surfaces under conditions of energy limitation. we employ the term morphotype to refer to specific properties of colonial development. the morphologies we discuss include a tip-splitti ... | 1998 | 9891813 |
| a nusg-like transcription anti-terminator is involved in the biosynthesis of the polyketide antibiotic ta of myxococcus xanthus. | the antibiotic ta of myxococcus xanthus is synthesized through a type i polyketide synthase mechanism. previous studies have indicated that several genes essential for ta production are clustered within a 40-kb region and are transcriptionally co-regulated. in this study, we report the genetic analysis of the first gene in the ta gene cluster, identified as a nusg-like transcription anti-terminator. functional analysis of this nusg-like anti-terminator gene by specific gene disruption confirms t ... | 1999 | 9919671 |
| the first gene in the biosynthesis of the polyketide antibiotic ta of myxococcus xanthus codes for a unique pks module coupled to a peptide synthetase. | the polyketide antibiotic ta is synthesized by the gram negative bacterium myxococcus xanthus in a multi-step process in which a unique glycine-derived molecule is used as a starter unit and elongated through the condensation of 11 acetate molecules by polyketide synthases (pkss). analysis of a 7.2 kb dna fragment, encoding the protein that carries out the first condensation step, revealed that the fragment constitutes a single open reading frame, referred to as ta1, which lacks the 5' and 3' en ... | 1999 | 9973564 |
| a new set of chemotaxis homologues is essential for myxococcus xanthus social motility. | myxococcus xanthus cells aggregate and develop into multicellular fruiting bodies in response to starvation. a new m. xanthus locus, designated diffor defective in fruiting, was identified by the characterization of a mutant defective in fruiting body formation. molecular cloning, dna sequencing and sequence analysis indicate that the dif locus encodes a new set of chemotaxis homologues of the bacterial chemotaxis proteins mcps (methyl-accepting chemotaxis proteins), chew, chey and chea. the dif ... | 1998 | 9988486 |
| regulated exopolysaccharide production in myxococcus xanthus. | myxococcus xanthus fibrils are cell surface-associated structures composed of roughly equal amounts of polysaccharide and protein. the level of m. xanthus polysaccharide production under different conditions in the wild type and in several mutants known to have alterations in fibril production was investigated. wild-type exopolysaccharide increased significantly as cells entered the stationary phase of growth or upon addition of ca2+ to growing cells, and the polysaccharide-induced cells exhibit ... | 1999 | 10049381 |
| the domains of protein s from myxococcus xanthus: structure, stability and interactions. | protein s from myxococcus xanthus is a member of the beta gamma-crystallin superfamily. its n and c-terminal domains (nps and cps, respectively) show a high degree of structural similarity and possess the capacity to bind two calcium ions per domain. for nps, their positions were determined by x-ray diffraction at 1.8 a resolution, making use of molecular replacement with the nmr structure as search model. the overall topology of nps is found to be practically the same as in complete protein s. ... | 1999 | 10064714 |
| cloning and characterization of a myxococcus xanthus cytochrome p-450 hydroxylase required for biosynthesis of the polyketide antibiotic ta. | the antibiotic ta, a complex macrocyclic polyketide of myxococcus xanthus, is produced, like many other polyketides, through successive condensations of acetate by a type i polyketide synthase (pks) mechanism. the chemical structure of this antibiotic and the mechanism by which it is synthesized indicate the need for several post-modification steps, such as a specific hydroxylation at c-20. previous studies have shown that several genes, essential for ta biosynthesis, are clustered in a region o ... | 1999 | 10072767 |
| the frua signal transduction protein provides a checkpoint for the temporal co-ordination of intercellular signals in myxococcus xanthus development. | during fruiting body morphogenesis in myxococcus xanthus, the intercellular c-signal induces aggregation, sporulation and developmental gene expression. to understand how a single signal system may induce temporally separated processes, we have focused on the class ii gene, which codes for an essential component in the c-signal transduction pathway. we report that class ii is identical to frua and codes for a dna binding response regulator. transcription of frua is developmentally regulated and ... | 1998 | 10094629 |
| the structure of an ecf-sigma-dependent, light-inducible promoter from the bacterium myxococcus xanthus. | expression of the myxococcus xanthus gene crtl is controlled by a light-inducible promoter. the activity of this promoter depends on carq, a sigma factor of the extracytoplasmic function (ecf) subfamily. here, we show thatthe minimum dna stretch reproducing normal expression of crtl extends from a few bases upstream of the -35 position to a site well downstream of the transcriptional start. the downstream dna contains an enhancer-like element that remains active when displaced upstream of the pr ... | 1998 | 10094635 |
| mutations that confer resistance to 2-deoxyglucose reduce the specific activity of hexokinase from myxococcus xanthus. | the glucose analog 2-deoxyglucose (2dglc) inhibits the growth and multicellular development of myxococcus xanthus. mutants of m. xanthus resistant to 2dglc, designated hex mutants, arise at a low spontaneous frequency. expression of the escherichia coli glk (glucokinase) gene in m. xanthus hex mutants restores 2dglc sensitivity, suggesting that these mutants arise upon the loss of a soluble hexokinase function that phosphorylates 2dglc to form the toxic intermediate, 2-deoxyglucose-6-phosphate. ... | 1999 | 10094702 |
| an erythromycin resistance cassette and mini-transposon for constructing transcriptional fusions to cat. | a new cassette (er-cm cassette) and mini-transposon (mtn) (tnmaxercm) based on the previously described mtn, tnmax2 [haas et al., gene 130, 23-31.], have been constructed. the cassette and mtn make use of an erythromycin resistance (err) marker encoded by ermc'. both the er-cm cassette and tnmaxercm also carry a promoterless cat gene to allow the construction of transcriptional fusions and the measurement of transcriptional activity by assaying for chloramphenicol acetyltransferase. we show the ... | 1999 | 10095104 |
| kr025, a new cytotoxic compound from myxococcus fulvus. | a new bithiazole, kr-025 (1), was isolated from myxococcus fulvus. its structure was elucidated by spectroscopic analysis. in addition to 1, the strain produced relatively large quantities of a second, closely related antibiotic, myxothiazol. these compounds demonstrated potent cytotoxicity against human tumor cells. | 1999 | 10096868 |
| gliding mutants of myxococcus xanthus with high reversal frequencies and small displacements. | myxococcus xanthus cells move on a solid surface by gliding motility. several genes required for gliding motility have been identified, including those of the a- and s-motility systems as well as the mgl and frz genes. however, the cellular defects in gliding movement in many of these mutants were unknown. we conducted quantitative, high-resolution single-cell motility assays and found that mutants defective in mglab or in cglb, an a-motility gene, reversed the direction of gliding at frequencie ... | 1999 | 10198026 |
| secretion of atp-utilizing enzymes, nucleoside diphosphate kinase and atpase, by mycobacterium bovis bcg: sequestration of atp from macrophage p2z receptors? | mycobacterium bovis bcg secretes two atp-scavenging enzymes, nucleoside diphosphate kinase (ndk) and atpase, during growth in middlebrook 7h9 medium. in synthetic sauton medium without any protein supplements, there is less secretion of these two enzymes unless proteins such as bovine serum albumin (bsa), ovalbumin or extracts of macrophages are added to the medium. there is a gradient of activity among various proteins in triggering the induction of secretion of these two enzymes. other mycobac ... | 1999 | 10200955 |
| type iv pili and cell motility. | type iv pili (tfp) mediate the movement of bacteria over surfaces without the use of flagella. these movements are known as social gliding in myxococcus xanthus and twitching in organisms such as pseudomonas aeruginosa and neisseria gonorrhoeae. tfp are localized polarly. type iv pilins have a signature n-terminal domain, which forms a coiled-coil with other monomer units to polymerize a pilus fibre. at least 10 more proteins at the base of the fibre are conserved; they are related to the type i ... | 1999 | 10216854 |
| diffusion through agar blocks of finite dimensions: a theoretical analysis of three systems of practical significance in microbiology. | a number of experimental methods in biology depend on the kinetics of diffusion of a substance through a gel. this paper reviews the diffusion equations, gives the experimental limitations for some useful cases, and presents computer simulations for cases that cannot be treated analytically. while double diffusion is not considered, three single-diffusion situations are treated. (1) systems for the study of chemotaxis in the gliding bacterium myxococcus xanthus. experimental designs used for thi ... | 1999 | 10217498 |
| the cell surface-associated intercellular c-signal induces behavioral changes in individual myxococcus xanthus cells during fruiting body morphogenesis. | fruiting body formation in myxococcus xanthus depends on ordered changes in cell movements from swarming to aggregation in response to starvation. we show that appropriately starved individual cells change behavior during fruiting body formation. specifically, from the time of initiation of aggregation, individual wild-type cells began to move with increased gliding speeds, the duration of the mean gliding interval increased, and the stop frequency decreased whereas the duration of the mean stop ... | 1999 | 10220413 |
| site-specific recombination of temperate myxococcus xanthus phage mx8: genetic elements required for integration. | like most temperate bacteriophages, phage mx8 integrates into a preferred locus on the genome of its host, myxococcus xanthus, by a mechanism of site-specific recombination. the mx8 int-attp genes required for integration map within a 2.2-kilobase-pair (kb) fragment of the phage genome. when this fragment is subcloned into a plasmid vector, it facilitates the site-specific integration of the plasmid into the 3' ends of either of two tandem trnaasp genes, trnd1 and trnd2, located within the attb ... | 1999 | 10383974 |
| site-specific recombination of temperate myxococcus xanthus phage mx8: regulation of integrase activity by reversible, covalent modification. | temperate myxococcus xanthus phage mx8 integrates into the attb locus of the m. xanthus genome. the phage attachment site, attp, is required in cis for integration and lies within the int (integrase) coding sequence. site-specific integration of mx8 alters the 3' end of int to generate the modified intx gene, which encodes a less active form of integrase with a different c terminus. the phage-encoded (int) form of integrase promotes attp x attb recombination more efficiently than attr x attb, at ... | 1999 | 10383975 |
| scoc regulates peptide transport and sporulation initiation in bacillus subtilis. | oligopeptides are transported into bacillus subtilis by two abc transport systems, app and opp. transcription of the operon encoding the opp system was found to occur during exponential growth, whereas the app operon was induced at the onset of stationary phase. transcription of both operons was completely curtailed by overproduction of the scoc regulator from a multicopy plasmid and was enhanced in strains with the scoc locus deleted. scoc, a member of the marr family of transcription regulator ... | 1999 | 10383984 |
| cell fate and organogenesis in bacteria. | intercellular signaling through the notch receptor and its ligands leads to the spatial differentiation of cell fate in vertebrates and invertebrates. in myxococcus xanthus, fruiting-body development requires the transmission of a cell-bound intercellular signal by the protein called c-factor, which is functionally equivalent to the eukaryotic notch ligands. functional parallels between these two signaling systems include strong positive and negative feedback, and a consequent role in spatial di ... | 1999 | 10390626 |
| myxococcus cells respond to elastic forces in their substrate. | elasticotaxis describes the ability of myxococcus xanthus cells to sense and to respond to elastic forces within an agar gel on which they rest. within 5 min of the application of stress, each cell begins to reorient its long axis perpendicular to the stress force. the cells then glide in that direction, and the swarm becomes asymmetric. a quantifiable assay for the strength of elasticotaxis is based on the change in swarm shape from circular to elliptic. by using a collection of isogenic motili ... | 1999 | 10393946 |
| genetic and molecular analysis of cglb, a gene essential for single-cell gliding in myxococcus xanthus. | gliding movements of individual isolated myxococcus xanthus cells depend on the genes of the a-motility system (agl and cgl genes). mutants carrying defects in those genes are unable to translocate as isolated cells on solid surfaces. the motility defect of cgl mutants can be transiently restored to wild type by extracellular complementation upon mixing mutant cells with wild-type or other motility mutant cells. to develop a molecular understanding of the function of a cgl protein in gliding mot ... | 1999 | 10400597 |
| genetic suppression analysis of an asga missense mutation in myxococcus xanthus. | the asga gene is required for generation of extracellular a signal, which serves as a cell-density signal for fruiting body development in myxococcus xanthus. the asga protein is a histidine protein kinase and consists of a receiver domain that is conserved among response regulators of two-component signal transduction systems, followed by a histidine protein kinase domain that is conserved among sensor proteins of two-component systems. asga is thought to function in a signal transduction pathw ... | 1999 | 10411256 |
| molecular cloning, sequence analysis, and characterization of a penicillin-resistant dd-carboxypeptidase of myxococcus xanthus. | we have cloned a gene, pdca, from the genomic library of myxococcus xanthus with an oligonucleotide probe representing conserved regions of penicillin-resistant dd-carboxypeptidases. the amino- and carboxy-terminal halves of the predicted pdca gene product showed significant sequence similarity to n-acetylmuramoyl-l-alanine amidase and penicillin-resistant dd-carboxypeptidase, respectively. the pdca gene was expressed in escherichia coli, and the characteristics of the gene product were similar ... | 1999 | 10419975 |
| the correlation between morphological and phylogenetic classification of myxobacteria. | in order to determine whether morphological criteria are suitable to affiliate myxobacterial strains to species, a phylogenetic analysis of 16s rdnas was performed on 54 myxobacterial strains that represented morphologically 21 species of the genera angiococcus, archangium, chondromyces, cystobacter, melittangium, myxococcus, polyangium and stigmatella, five invalid species and three unclassified isolates. the analysis included 12 previously published sequences. the branching pattern confirmed t ... | 1999 | 10425789 |
| identification of the omega4499 regulatory region controlling developmental expression of a myxococcus xanthus cytochrome p-450 system. | omega4499 is the site of a tn5 lac insertion in the myxococcus xanthus chromosome that fuses lacz expression to a developmentally regulated promoter. cell-cell interactions that occur during development, including c signaling, are required for normal expression of tn5 lac omega4499. the dna upstream of the omega4499 insertion has been cloned, and the promoter has been localized. analysis of the dna sequence downstream of the promoter revealed one complete open reading frame and a second partial ... | 1999 | 10464222 |
| fibrils as extracellular appendages of bacteria: their role in contact-mediated cell-cell interactions in myxococcus xanthus. | social behavior in the myxobacterium myxococcus xanthus involves epicellular, peritrichous appendages called fibrils. these are polysaccharide organelles containing a set of tightly adhering proteins. it is proposed that cell-cell contact is perceived by the fibrils and is mediated by the action of a fibrillar adp-ribosyl transferase. fibrils or fibril-like organelles have also been found on a variety of other gram-negative bacteria and at least one archaeon, and may mediate cell-cell contact be ... | 1999 | 10472185 |
| gliding motility in bacteria: insights from studies of myxococcus xanthus. | gliding motility is observed in a large variety of phylogenetically unrelated bacteria. gliding provides a means for microbes to travel in environments with a low water content, such as might be found in biofilms, microbial mats, and soil. gliding is defined as the movement of a cell on a surface in the direction of the long axis of the cell. because this definition is operational and not mechanistic, the underlying molecular motor(s) may be quite different in diverse microbes. in fact, studies ... | 1999 | 10477310 |
| a nonessential signal peptidase ii (lsp) of myxococcus xanthus might be involved in biosynthesis of the polyketide antibiotic ta. | myxococcus xanthus is a gram-negative soil bacterium that produces the polyketide antibiotic ta. in this study, we describe the analysis of an m. xanthus gene which encodes a homologue of the prolipoprotein signal peptidase ii (spase ii; lsp). overexpression of the m. xanthus spase ii in escherichia coli confers high levels of globomycin resistance, confirming its function as an spase ii. the m. xanthus gene encoding the lsp homologue is nonessential for growth, as determined by specific gene di ... | 1999 | 10482504 |
| characterization of the chromosomal aac(6')-iz gene of stenotrophomonas maltophilia. | the aac(6')-iz gene of stenotrophomonas maltophilia bm2690 encoding an aminoglycoside 6'-n-acetyltransferase was characterized. the gene was identified as a coding sequence of 462 bp corresponding to a protein with a calculated mass of 16,506 da, a value in good agreement with that of ca. 16,000 found by in vitro coupled transcription-translation. analysis of the deduced amino acid sequence indicated that the protein was a member of the major subfamily of aminoglycoside 6'-n-acetyltransferases. ... | 1999 | 10508008 |
| calorimetric analysis of the ca(2+)-binding betagamma-crystallin homolog protein s from myxococcus xanthus: intrinsic stability and mutual stabilization of domains. | the betagamma-crystallin superfamily consists of a class of homologous two-domain proteins with greek-key fold. protein s, a ca(2+)-binding spore-coat protein from the soil bacterium myxococcus xanthus exhibits a high degree of sequential and structural homology with gammab-crystallin from the vertebrate eye lens. in contrast to gammab-crystallin, which undergoes irreversible aggregation upon thermal unfolding, protein s folds reversibly and may therefore serve as a model in the investigation of ... | 1999 | 10512720 |
| induction of beta-lactamase influences the course of development in myxococcus xanthus. | myxococcus xanthus is a gram-negative bacterium that develops in response to starvation on a solid surface. the cells assemble into multicellular aggregates in which they differentiate from rod-shaped cells into spherical, environmentally resistant spores. previously, we have shown that the induction of beta-lactamase is associated with starvation-independent sporulation in liquid culture (k. a. o'connor and d. r. zusman, mol. microbiol. 24:839-850, 1997). in this paper, we show that the chromos ... | 1999 | 10515921 |
| a re-examination of twitching motility in pseudomonas aeruginosa. | twitching motility is a form of solid surface translocation which occurs in a wide range of bacteria and which is dependent on the presence of functional type iv fimbriae or pili. a detailed examination of twitching motility in pseudomonas aeruginosa under optimal conditions in vitro was carried out. under these conditions (at the smooth surface formed between semi-solid growth media and plastic or glass surfaces) twitching motility is extremely rapid, leading to an overall radial rate of colony ... | 1999 | 10537208 |
| identification and characterization of five cspa homologous genes from myxococcus xanthus. | escherichia coli contains a large cspa family consisting of nine homologues, in which four are cold-shock inducible and one is stationary-phase inducible. here, we demonstrate that myxococcus xanthus possesses at least five cspa homologues, cspa to cspe. hydrophobic residues forming a hydrophobic core, and aromatic residues, which are included in functional motifs rnp-1 and rnp-2 involved in binding to rna and ssdna, are well conserved. these facts suggest that m. xanthus cspa homologues have a ... | 1999 | 10542339 |
| conservation of the pyrrolnitrin biosynthetic gene cluster among six pyrrolnitrin-producing strains. | the prnabcd gene cluster from pseudomonas fluorescens encodes the biosynthetic pathway for pyrrolnitrin, a secondary metabolite derived from tryptophan which has strong anti-fungal activity. we used the prn genes from p. fluorescens strain bl915 as a probe to clone and sequence homologous genes from three other pseudomonas strains, burkholderia cepacia and myxococcus fulvus. with the exception of the prna gene from m. fulvus59% similar among the strains, indicating that the biochemical pathway f ... | 1999 | 10547442 |
| intercellular signaling during fruiting-body development of myxococcus xanthus. | the myxobacterium myxococcus xanthus has a life cycle that is dominated by social behavior. during vegetative growth, cells prey on other bacteria in large groups that have been likened to wolf packs. when faced with starvation, cells form a macroscopic fruiting body containing thousands of spores. the social systems that guide fruiting body development have been examined through the isolation of conditional developmental mutants that can be stimulated to develop in the presence of wild-type cel ... | 1999 | 10547700 |
| asgd, a new two-component regulator required for a-signalling and nutrient sensing during early development of myxococcus xanthus. | myxococcus xanthus has a complex life cycle that includes fruiting body formation. one of the first stages in development has been called a-signalling. the asg (a-signalling) mutants have been proposed to be deficient in producing a-signal, resulting in development arresting at an early stage. in this paper, we report the identification of a new asg locus asgd. this locus appears to be involved in both environmental sensing and intercellular signalling. expression of asgd was undetected during v ... | 1999 | 10564471 |
| sporulation timing in myxococcus xanthus is controlled by the espab locus. | the fruiting body development of myxococcus xanthus consists of two separate but interacting pathways: one for aggregation of many cells to form raised mounds and the other for sporulation of individual cells into myxospores. sporulation of individual cells normally occurs after mound formation, and is delayed at least 30 h after starvation under our laboratory conditions. this suggests that m. xanthus has a mechanism that monitors progress towards aggregation prior to triggering sporulation. a ... | 1999 | 10564511 |
| melithiazols, new beta-methoxyacrylate inhibitors of the respiratory chain isolated from myxobacteria. production, isolation, physico-chemical and biological properties. | new antibiotic compounds, melithiazols, were isolated from the culture broth of strains of the myxobacteria melittangium lichenicola, archangium gephyra, and myxococcus stipitatus. the compounds belong to the group of beta-methoxyacrylate (moa) inhibitors and are related to the myxothiazols. the melithiazols show high antifungal activity, but are less toxic than myxothiazol a and its methyl ester in a growth inhibition assay with mouse cell cultures. the melithiazols inhibit nadh oxidation by su ... | 1999 | 10580385 |
| genetic and functional analysis of genes required for the post-modification of the polyketide antibiotic ta of myxococcus xanthus. | the antibiotic ta of myxococcus xanthus is a complex macrocyclic polyketide, produced through successive condensations of acetate by a type i pks (polyketide synthase) mechanism. the genes encoding ta biosynthesis are clustered on a 36 kb dna fragment, which has been cloned and analysed. the chemical structure of ta and the mechanism by which it is synthesized indicate the need for several post-modification steps, which are introduced into the carbon chain of the polyketide to form the final bio ... | 1999 | 10589713 |
| motility in myxococcus xanthus and its role in developmental aggregation. | the frz signal transduction system of myxococcus xanthus was originally thought to be a simple variation of the well-characterized che system of the enteric bacteria. recently, however, many additional frz proteins, along with alternative signal transduction systems, have been discovered. together these signal transduction pathways coordinate cell-cell behavior, permitting the complex interactions required for developmental aggregation and fruiting body formation. | 1999 | 10607622 |
| effect of cellular filamentation on adventurous and social gliding motility of myxococcus xanthus. | filamentous bacterial cells often provide biological information that is not readily evident in normal-size cells. in this study, the effect of cellular filamentation on gliding motility of myxococcus xanthus, a gram-negative social bacterium, was investigated. elongation of the cell body had different effects on adventurous and social motility of m. xanthus. the rate of a-motility was insensitive to cell-body elongation whereas the rate of s-motility was reduced dramatically as the cell body go ... | 1999 | 10611358 |
| sequences and evolutionary analyses of eukaryotic-type protein kinases from streptomyces coelicolor a3(2). | four eukaryotic-type protein serine/threonine kinases from streptomyces coelicolor a3(2) were cloned and sequenced. to explore evolutionary relationships between these and other protein kinases, the distribution of protein serine/threonine kinase genes in prokaryotes was examined with the tfasta program. genes of this type were detected in only a few species of prokaryotes and their distribution was uneven; streptomyces, mycobacterium, synechocystis and myxococcus each contained more than three ... | 1999 | 10627033 |
| disruption of alda influences the developmental process in myxococcus xanthus. | previously, we identified a gene (alda) from myxococcus xanthus, which we suggested encoded the enzyme alanine dehydrogenase on the basis of similarity to known ald protein sequences (m. j. ward, h. lew, a. treuner-lange, and d. r. zusman, j. bacteriol. 180:5668-5675, 1998). in this study, we have confirmed that alda does encode a functional alanine dehydrogenase, since it catalyzes the reversible conversion of alanine to pyruvate and ammonia. whereas an alda gene disruption mutation did not sig ... | 2000 | 10629210 |
| the stringent response in myxococcus xanthus is regulated by soce and the csga c-signaling protein. | myxococcus xanthus fruiting body development is induced by amino acid limitation. the decision to grow or develop is established by the rela-dependent stringent response and a-signaling. we identified two new members of this regulatory hierarchy, soce and the c-signaling gene csga. soce depletion arrests growth and induces sporulation under conditions that normally favor growth as well as curtailing dna and stable rna synthesis, inhibiting cell elongation, and inducing accumulations of the strin ... | 2000 | 10691740 |
| the asge locus is required for cell-cell signalling during myxococcus xanthus development. | in response to starvation, myxococcus xanthus undergoes a multicellular developmental process that produces a dome-shaped fruiting body structure filled with differentiated cells called myxospores. two insertion mutants that block the final stages of fruiting body morphogenesis and reduce sporulation efficiency were isolated and characterized. dna sequence analysis revealed that the chromosomal insertions are located in open reading frames orf2 and asge, which are separated by 68 bp. the sporula ... | 2000 | 10692158 |
| evolution of arginine biosynthesis in the bacterial domain: novel gene-enzyme relationships from psychrophilic moritella strains (vibrionaceae) and evolutionary significance of n-alpha-acetyl ornithinase. | in the arginine biosynthetic pathway of the vast majority of prokaryotes, the formation of ornithine is catalyzed by an enzyme transferring the acetyl group of n-alpha-acetylornithine to glutamate (ornithine acetyltransferase [oatase]) (argj encoded). only two exceptions had been reported-the enterobacteriaceae and myxococcus xanthus (members of the gamma and delta groups of the class proteobacteria, respectively)-in which ornithine is produced from n-alpha-acetylornithine by a deacylase, acetyl ... | 2000 | 10692366 |
| a sigma(54) activator protein necessary for spore differentiation within the fruiting body of myxococcus xanthus. | insertion of an internal dna fragment into the act1 gene, which encodes one of several sigma(54)-activator proteins in myxococcus xanthus, produced a mutant defective in fruiting body development. while fruiting-body aggregation appears normal in the mutant, it fails to sporulate (<10(-6) the wild-type number of viable spores). the a and c intercellular signals, which are required for sporulation, are produced by the mutant. but, while it produces a-factor at levels as high as that of the wild t ... | 2000 | 10762243 |
| bacterial cheaters. | | 2000 | 10766222 |
| developmental cheating in the social bacterium myxococcus xanthus. | cheating is a potential problem in any social system that depends on cooperation and in which actions that benefit a group are costly to individuals that perform them. genetic mutants that fail to perform a group-beneficial function but that reap the benefits of belonging to the group should have a within-group selective advantage, provided that the mutants are not too common. here we show that social cheating exists even among prokaryotes. the bacterium myxococcus xanthus exhibits several socia ... | 2000 | 10766241 |
| effect of culture conditions on the formation of struvite by myxococcus xanthus. | the amount of struvite (mgnh4po4 x 6h2o) produced by myxococcus xanthus as well as the culture parameter values (ph, total phosphorus, total kjeldahl nitrogen) were dependent on the culture medium used. struvite formation started during the exponential phase and the maximum concentration was observed at the beginning of stationary growth phase. the addition of each medium component to the liquid culture influenced the amount of crystal produced. this amount did not depend on the ph increase duri ... | 2000 | 10789967 |
| purification and characterization of a novel lectin from a freshwater cyanobacterium, oscillatoria agardhii. | in the survey of 14 species of laboratory-cultured cyanobacteria for hemagglutinins, we newly detected the activity in two species, oscillatoria agardhii, strain nies-204, and phormidium foveolarum, strain nies-503. from the extract of o. agardhii, which showed the highest activity with trypsin-treated erythrocytes of rabbit, a lectin was purified to homogeneity by the combination of precipitation with (nh4)2so4, gel filtration, hydrophobic chromatography and reverse phase chromatography. the pu ... | 2000 | 10817903 |
| aglu, a protein required for gliding motility and spore maturation of myxococcus xanthus, is related to wd-repeat proteins. | the aglu gene of myxococcus xanthus encodes a protein similar to het-e1 (vegetative incompatibility) from podospora anserina, acylaminoacyl-peptidase from bacillus subtilis, and tolb from escherichia coli. these proteins all have evenly spaced spdg repeats that are characteristic of a larger motif called the wd-repeat. the wd-repeat is predicted to form a beta-propeller structure that mediates the assembly of heteromeric protein complexes. aglu has a consensus lipoprotein attachment motif that i ... | 2000 | 10844655 |
| a common step for changing cell shape in fruiting body and starvation-independent sporulation of myxococcus xanthus. | myxococcus xanthus can sporulate in either of two ways: at the end of the program of fruiting body development or after exposure of growing cells to certain reagents such as concentrated glycerol. fruiting body sporulation requires starvation, while glycerol sporulation requires rapid growth, and since the two types of spores are structurally somewhat different, it has generally been assumed that the two processes are different. however, a tn5 lac insertion mutation, omega7536, has been isolated ... | 2000 | 10852889 |
| developmental cheating and the evolutionary biology of dictyostelium and myxococcus. | | 2000 | 10878115 |
| fructose utilization and pathogenicity of spiroplasma citri: characterization of the fructose operon. | transposon tn4001 mutagenesis of spiroplasma citri wild-type (wt) strain gii-3 led to the isolation and characterization of non-phytopathogenic mutant gmt 553. in this mutant, transposon tn4001 is inserted within the first gene of the fructose operon. this operon comprises three genes. the first gene (frur) codes for a putative transcriptional regulator protein belonging to the deoxyribonucleoside repressor (deor) family. sequence similarities and functional complementation of mutant gmt 553 wit ... | 2000 | 10903438 |
| identification and characterization of genes required for early myxococcus xanthus developmental gene expression. | starvation and cell density regulate the developmental expression of myxococcus xanthus gene 4521. three classes of mutants allow expression of this developmental gene during growth on nutrient agar, such that colonies of strains containing a tn5 lac omega4521 fusion are lac(+). one class of these mutants inactivates sasn, a negative regulator of 4521 expression; another class activates sass, a sensor kinase-positive regulator of 4521 expression; and a third class blocks lipopolysaccharide (lps) ... | 2000 | 10913090 |
| spatial control of cell differentiation in myxococcus xanthus. | myxococcus xanthus develops species-specific multicellular fruiting bodies. starting from a uniform mat of cells, some cells enter into nascent fruiting body aggregates, whereas other cells remain outside. the cells within the fruiting body differentiate from rods into spherical, heat-resistant spores, whereas the cells outside the aggregates, called peripheral cells, remain rod-shaped. early developmentally regulated genes are expressed in peripheral cells as well as by cells in the fruiting bo ... | 2000 | 10922065 |
| the myxococcus xanthus soce and csga genes are regulated by the stringent response. | disruption of the myxococcus xanthus soce gene bypasses the requirement for the cell contact-dependent c-signalling system mediated by csga and restores fruiting body morphogenesis and spore differentiation. the soce gene has been identified by genetic complementation, cloned and sequenced. soce is highly basic, unique and is predicted to be a soluble protein with a molecular size of 53. 6 kda. the soce and csga genes have opposite transcription patterns during the m. xanthus life cycle. soce ex ... | 2000 | 10972801 |
| fructose operon mutants of spiroplasma citri. | fructose-negative mutants of spiroplasma citri wild-type strain gii-3 were selected by two methods. the first method is based on the selection of spontaneous xylitol-resistant mutants, xylitol being a toxic fructose analogue. five such mutants were obtained, but only one, xyl3, was unable to use fructose and had no phosphoenolpuryvate:fructose phosphotransferase system (fructose-pts) activity. amplification and sequencing of the fructose permease gene of mutant xyl3 revealed the presence of an a ... | 2000 | 10974110 |
| programmed death in bacteria. | programmed cell death (pcd) in bacteria plays an important role in developmental processes, such as lysis of the mother cell during sporulation of bacillus subtilis and lysis of vegetative cells in fruiting body formation of myxococcus xanthus. the signal transduction pathway leading to autolysis of the mother cell includes the terminal sporulation sigma factor esigma(k), which induces the synthesis of autolysins cwlc and cwlh. an activator of autolysin in this and other pcd processes is yet to ... | 2000 | 10974124 |
| molecular cloning and characterization of two genes for the biotin carboxylase and carboxyltransferase subunits of acetyl coenzyme a carboxylase in myxococcus xanthus. | we have cloned a dna fragment from a genomic library of myxococcus xanthus using an oligonucleotide probe representing conserved regions of biotin carboxylase subunits of acetyl coenzyme a (acetyl-coa) carboxylases. the fragment contained two open reading frames (orf1 and orf2), designated the accb and acca genes, capable of encoding a 538-amino-acid protein of 58.1 kda and a 573-amino-acid protein of 61.5 kda, respectively. the protein (acca) encoded by the acca gene was strikingly similar to b ... | 2000 | 10986250 |
| type iv pilus of myxococcus xanthus is a motility apparatus controlled by the frz chemosensory system. | although flagella are the best-understood means of locomotion in bacteria [1], other bacterial motility mechanisms must exist as many diverse groups of bacteria move without the aid of flagella [2-4]. one unusual structure that may contribute to motility is the type iv pilus [5,6]. genetic evidence indicates that type iv pili are required for social gliding motility (s-motility) in myxococcus, and twitching motility in pseudomonas and neisseria [6,7]. it is thought that type iv pili may retract ... | 2000 | 10996798 |
| social motility in myxococcus xanthus requires frzs, a protein with an extensive coiled-coil domain. | gliding motility in the developmental bacterium myxococcus xanthus involves two genetically distinct motility systems, designated adventurous (a) and social (s). directed motility responses, which facilitate both vegetative swarming and developmental aggregation, additionally require the 'frizzy' (frz) signal transduction pathway. in this study, we have analysed a new gene (frzs), which is positioned upstream of the frza-f operon. insertion mutations in frzs caused both vegetative spreading and ... | 2000 | 10998168 |
| myxococcus xanthus dif genes are required for biogenesis of cell surface fibrils essential for social gliding motility. | myxococcus xanthus social (s) gliding motility has been previously reported by us to require the chemotaxis homologues encoded by the dif genes. in addition, two cell surface structures, type iv pili and extracellular matrix fibrils, are also critical to m. xanthus s motility. we have demonstrated here that m. xanthus dif genes are required for the biogenesis of fibrils but not for that of type iv pili. furthermore, the developmental defects of dif mutants can be partially rescued by the additio ... | 2000 | 11004179 |
| myxococcus xanthus fibril appendages are essential for excitation by a phospholipid attractant. | isolated (a-motile) myxococcus xanthus cells glide over solid surfaces and display excitation, a suppression of direction reversals, when presented with phosphatidylethanolamine (pe) purified from its own membranes or synthetic dilauroyl pe and dioleoyl pe. although the mechanism of pe signal transduction is unknown, we hypothesized that m. xanthus might use surface-associated factors to detect exogenous pe to prevent endogenous lipids from self-stimulating the sensory system. peritrichous prote ... | 2000 | 11016978 |
| evolution of viruses by acquisition of cellular rna or dna nucleotide sequences and genes: an introduction. | the origins of virus evolution may be traced to archeabacteria since inouye and inouye (6) discovered a retroelement with a gene for reverse transcriptase in the bacterial genome and in the satellite, multiple copy single stranded dna (msdna) in the soil bacterium myxococcus xanthus. it was possible (8) to define the evolution of retroelements in eukaryotic cells of plants, insects (gypsy retrovirus) and vertebrates. the replication of rna viruses in eukaryotic cells allowed for the viral rna ge ... | 2000 | 11022785 |
| cloning and expression of isocitrate lyase from human round worm strongyloides stercoralis. | a full length cdna (1463 bp) encoding isocitrate lyase (ec 4.1.3.1) of strongyloides stercoralis is described. the nucleotide sequence of this insert identified a cdna coding for the isocitrate lyase. the conceptually translated amino acid sequence of the open reading frame for s. stercoralis isocitrate lyase encodes a 450 amino acid residue protein with an apparent molecular weight of 50 kda and a predicted pl of 6.39. the sequence is 69% a/t, reflecting a characteristic a/t codon bias of s. st ... | 2000 | 11031761 |
| effect of the adhesive antibiotic ta on adhesion and initial growth of e. coli on silicone rubber. | catheter-associated urinary tract infection is the most common nosocomial infection, and contributes to patient morbidity and mortality. we investigated the effect that the ta adhesive antibiotic had on adhesion and initial growth in urine of escherichia coli on silicone rubber. the ta antibiotic had reduced adhesion, and inhibited initial growth of the bacteria on the surface. since adhesion and initial growth on the surface are an essential part of biofilm formation and subsequent infection, w ... | 2000 | 11040435 |
| [frua, a transcription factor in myxococus xamthus, regulates transcription of target genes in collaboration with the associated protein frub]. | many developmental genes are regulated by frua, a transcription factor essential for the development of myxococus xamthus. another protein, designated frub, was purified from myxobacteria by its affinity to frua. frub could be phosphorylated by protein kinase(s) located in cell membrane. gel shift assay showed that frua regulates transcription of target genes in collaboration with phosphorylated frub. this study may shed light on the molecular mechanisms of regulatory network involved in the dev ... | 2000 | 11057053 |
| phenotypic analyses of frz and dif double mutants of myxococcus xanthus. | myxococcus xanthus is a gram-negative gliding bacterium that aggregates and develops into multicellular fruiting bodies in response to starvation. two chemosensory systems (frz and dif), both of which are homologous to known chemotaxis proteins, were previously identified through characterization of various developmental mutants. this study aims to examine the interaction between these two systems since both of them are required for fruiting body formation of m. xanthus. through detailed phenoty ... | 2000 | 11064197 |
| mechanisms of apoptosis. | programmed cell death plays critical roles in a wide variety of physiological processes during fetal development and in adult tissues. in most cases, physiological cell death occurs by apoptosis as opposed to necrosis. defects in apoptotic cell death regulation contribute to many diseases, including disorders where cell accumulation occurs (cancer, restenosis) or where cell loss ensues (stroke, heart failure, neurodegeneration, aids). in recent years, the molecular machinery responsible for apop ... | 2000 | 11073801 |
| developmental aggregation of myxococcus xanthus requires frga, an frz-related gene. | myxococcus xanthus is a gram-negative bacterium which has a complex life cycle that includes multicellular fruiting body formation. frizzy mutants are characterized by the formation of tangled filaments instead of hemispherical fruiting bodies on fruiting agar. mutations in the frz genes have been shown to cause defects in directed motility, which is essential for both vegetative swarming and fruiting body formation. in this paper, we report the discovery of a new gene, called frga (for frz-rela ... | 2000 | 11073903 |
| control of asge expression during growth and development of myxococcus xanthus. | one of the earliest events in the myxococcus xanthus developmental cycle is production of an extracellular cell density signal called a-signal (or a-factor). previously, we showed that cells carrying an insertion in the asge gene fail to produce normal levels of this cell-cell signal. in this study we found that expression of asge is growth phase regulated and developmentally regulated. several lines of evidence indicate that asge is cotranscribed with an upstream gene during development. using ... | 2000 | 11073904 |
| identification of a substrate for pkn2, a protein ser/thr kinase from myxococcus xanthus by a novel method for substrate identification. | eukaryotic cells contain a large number of protein ser/ thr kinases, which play important roles in signal transduction required for cell proliferation, differentiation, and stress response and adaptation. it is also known that some prokaryotes contain a family of protein ser/thr kinases. a major challenge in the characterization of these kinases is how to identify their specific substrates. here we developed such a method using a protein ser/thr kinase, pkn2 from myxococcus xanthus, a gram-negat ... | 2000 | 11075932 |
| a large family of eukaryotic-like protein ser/thr kinases of myxococcus xanthus, a developmental bacterium. | myxococcus xanthus is a gram-negative bacterium that forms multicellular fruiting bodies upon starvation. here, we demonstrate that it contains at least 13 eukaryotic-like protein ser/thr kinases (pkn1 to pkn13) individually having unique features. all contain the kinase domain of approximately 280 residues near the n-terminal end, which share highly conserved features in eukaryotic ser/thr kinases. the kinase domain is followed by a putative regulatory domain consisting of 185 to 692 residues. ... | 2000 | 11087177 |
| inorganic polyphosphate kinase and adenylate kinase participate in the polyphosphate:amp phosphotransferase activity of escherichia coli. | polyphosphate kinase (ppk), responsible for the processive synthesis of inorganic polyphosphate (polyp) from atp in escherichia coli, can transfer in reverse the terminal phosphate residue of polyp to adp to yield atp. polyp also serves as a donor in a polyp:amp phosphotransferase (pap) activity observed in extracts of acinetobacter johnsonii and myxococcus xanthus. we have found that overexpression of the gene encoding ppk results in a large enhancement of pap activity in e. coli. the pap activ ... | 2000 | 11106368 |