Publications

temperate myxococcus xanthus phage mx8 encodes a dna adenine methylase, mox.	temperate bacteriophage mx8 of myxococcus xanthus encapsidates terminally repetitious dna, packaged as circular permutations of its 49-kbp genome. during both lytic and lysogenic development, mx8 expresses a nonessential dna methylase, mox, which modifies adenine residues in occurrences of xhoi and psti recognition sites, ctcgag and ctgcag, respectively, on both phage dna and the host chromosome. the mox gene is necessary for methylase activity in vivo, because an amber mutation in the mox gene ...	1997	9209041
the tgl gene: social motility and stimulation in myxococcus xanthus.	mutations in the tgl locus inactivate social gliding motility in myxococcus xanthus and block production of pili. the tgl locus is distinctive among the genes for social motility because social gliding and pili can be restored transiently to tgl mutant cells by mixing them with tgl+ cells, a process known as stimulation. the tgl locus was cloned with a linked insertion of transposon tn5 by using the kanamycin resistance encoded by that transposon. a 16-kb segment of chromosomal dna complemented ...	1997	9209055
identification and localization of the tgl protein, which is required for myxococcus xanthus social motility.	tgl protein is required for the production of the type iv pili found at a pole of the myxococcus xanthus cell. these pili are essential for social motility. evidence is presented that tgl is a membrane protein, based on experiments with polyclonal antibody specific for tgl that was raised against the fusion proteins beta-galactosidase-tgl and trpe-tgl. immunoaffiity-purified antibody reacted with a protein in m. xanthus having an apparent molecular mass of 27.5 kda as measured by sodium dodecyl ...	1997	9209056
regulation of directed motility in myxococcus xanthus.	myxococcus xanthus is a gram-negative bacterium that exhibits a complex life cycle. during vegetative growth, cells move as large swarms. however, when starved, cells aggregate into fruiting bodies and sporulate. both vegetative swarming and developmental aggregation require gliding motility, which involves the slow movement of cells on a solid surface in the absence of flagella. the frequency of cell reversals controls the direction of movement and is regulated by the frz genes, which encode th ...	1997	9219997
molecular genetic analysis of type-4 pilus biogenesis and twitching motility using pseudomonas aeruginosa as a model system--a review.	genetic analysis of pseudomonas aeruginosa pilus biogenesis and twitching motility has revealed the requirement for several pil loci which have been localized to different regions of the chromosome. one pil locus, designated pile, resides at approx. 71 min on the pao genetic map, a region of the chromosome previously shown to harbor a number of genes required for pilus assembly (i.e., pila, -b, -c, -d, -r and -s). the pile protein shows significant sequence identity to the n-terminal domain of p ...	1997	9224880
complementation of sporulation and motility defects in a prokaryote by a eukaryotic gtpase.	the complex prokaryote, myxococcus xanthus, undergoes a program of multicellular development when starved for nutrients, culminating in sporulation. m. xanthus makes mgla, a 22-kda, soluble protein that is required for both multicellular development and gliding motility. mgla is similar in sequence to the saccharomyces cerevisiae sar1 protein, a member of the ras/rab/rho superfamily of small eukaryotic gtpases. the sar1 gene, when integrated into the m. xanthus genome, complements the sporulatio ...	1997	9275220
a crtb homolog essential for photochromogenicity in mycobacterium marinum: isolation, characterization, and gene disruption via homologous recombination.	a gene essential for light-induced pigment production was isolated from the photochromogen mycobacterium marinum by heterologous complementation of an m. marinum cosmid library in the nonchromogen mycobacterium smegmatis. this gene is part of an operon and homologous to the streptomyces griseus and myxococcus xanthus crtb genes encoding phytoene synthase. gene replacement at this locus was achieved via homologous recombination, demonstrating that its expression is essential for photochromogenici ...	1997	9294446
in vitro transcription of myxococcus xanthus genes with rna polymerase containing sigmaa, the major sigma factor in growing cells.	myxococcus xanthus is a gram-negative bacterium that undergoes multicellular development upon starvation. we have developed a simple and rapid procedure for partial purification of rna polymerase from growing m. xanthus cells, using heparin-agarose and dna-cellulose chromatographies. in addition to core subunits, the enzyme contains one fairly abundant polypeptide of approximately 105 kda. we have shown by western blot analysis and protein sequencing that the 105-kda polypeptide is sigmaa, the p ...	1997	9302009
picture story. an eye on crystallins.		1997	9302991
sequence of the bacillus subtilis genome region in the vicinity of the lev operon reveals two new extracytoplasmic function rna polymerase sigma factors sigv and sigz.	two regions with sizes 18,900 and 25,400 bp, which join previously known contigs containing levrdefg, aadk and blt genes near 235 degrees of the bacillus subtilis chromosome, were sequenced. among others, two genes, which encode proteins homologous to rna polymerase sigma-factors, were identified within this region. the gene products designated sigv and sigz, show the highest homology with sigma-factors encoded by the gene carq of myxococcus xanthus and sigx (formerly orfx20) of b. subtilis, cor ...	1997	9308178
trans-acting regulation of antibiotic ta genes in myxococcus xanthus.	two regulatory mutations of myxococcus xanthus, which cause an increase in the transcription of genes required for antibiotic ta synthesis, were mapped by transduction and their effect on transcription of four ta genes examined. the two regulatory mutations were closely linked and located within the 40-kb ta gene cluster on the m. xanthus chromosome. recombinants were constructed which contained one of the regulatory mutations and promoter probes in the four different ta genes. both regulatory m ...	1997	9351195
cloning and sequencing of two genes, prta and prtb, from myxococcus xanthus, encoding prta and prtb proteases, both of which are required for the protease activity.	the sequence of a 1955-bp taqi dna fragment from myxococcus xanthus was determined. this fragment contains two complete genes, designated prta and prtb. the prta and prtb orfs extend over 828 and 798 bp, respectively. they are separated only by 3 nt and appear to be present in a polycistronic transcriptional unit. a typical lipoprotein signal sequence is present at the n terminus of the two deduced polypeptides. the aa sequence of prta shows a high degree of identity to the region adjacent to th ...	1997	9370274
propionyl coenzyme a carboxylase is required for development of myxococcus xanthus.	a dcm-1 mutant, obtained by transposon mutagenesis of myxococcus xanthus, could aggregate and form mounds but was unable to sporulate under nutrient starvation. a sequence analysis of the site of insertion of the transposon showed that the insertion lies within the 3' end of a 1,572-bp open reading frame (orf) designated the m. xanthus pccb orf. the wild-type form of the m. xanthus pccb gene, obtained from a lambdaembl library of m. xanthus, shows extensive similarity to a beta subunit of propio ...	1997	9371458
comparative heavy metal biosorption study of brewery yeast and myxococcus xanthus biomass.	the biosorption for la2+, co2+, mn2+, uo2(2+), pb2+, ag+, zn2+, cd2+ and cr2+ by wet and dry biomass form myxococcus xanthus obtained from laboratory cultures and saccharomyces cerevisiae from the brewing industry has been studied. m. xanthus biomass was found to be the most efficient biosorbent for all of the metals assayed. however, due to the fact that s. cerevisiae is a low cost residual by-product from the brewing industry, and at the same time yields good levels of biosorption, it is consi ...	1997	9375355
rapid purification and characterization of nucleoside diphosphate kinase isoforms using atp-sepharose affinity column chromatography.	nucleoside diphosphate kinases (ndp kinases), products of the nm23 gene, catalyze the transfer of the terminal phosphate group of the nucleoside triphosphate to the corresponding diphosphate and may be involved in tumor metastasis suppression, development, and signal transduction. ndp kinase from various sources including human erythrocytes, rat brain tissue and e. coli strain bl21 transformed with pet3c expression plasmids containing nm23-h1 or nm23-h2, were purified in one step to homogeneity ...	1997	9387150
a regulatory locus, pehsr, controls polygalacturonase production and other virulence functions in ralstonia solanacearum.	we previously identified a locus that regulates production of polygalacturonase (pg), an extracellular plant cell wall-degrading enzyme important in bacterial wilt of plants caused by ralstonia (pseudomonas) solanacearum. the dna sequence of this locus, called pehsr, was determined and two consecutive open reading frames (orfs) of 1,905 and 1,680 bp were identified. the amino acid sequences predicted to be encoded by these orfs are similar to those of regulators of pilin synthesis in pseudomonas ...	1997	9390420
regulation of expression of the pila gene in myxococcus xanthus.	type iv pili are required for social gliding motility in myxococcus xanthus. in this work, the expression of pilin (the pila gene product) during vegetative growth and fruiting-body development was examined. a polyclonal antibody against the pila gene product (prepilin) was prepared, along with a pila-lacz fusion, and was used to assay expression of pila in m. xanthus in different mutant backgrounds. pila expression required the response regulator pilr but was negatively regulated by the putativ ...	1997	9401034
myxococcus xanthus sass encodes a sensor histidine kinase required for early developmental gene expression.	initiation of myxococcus xanthus multicellular development requires integration of information concerning the cells' nutrient status and density. a gain-of-function mutation, sasb7, that bypasses both the starvation and high cell density requirements for developmental expression of the 4521 reporter gene, maps to the sass gene. the wild-type sass gene was cloned and sequenced. this gene is predicted to encode a sensor histidine protein kinase that appears to be a key element in the transduction ...	1997	9401035
a mutation that affects fibril protein, development, cohesion and gene expression in myxococcus xanthus.	extracellular matrix fibrils are involved in the cell-cell interactions of the social prokaryote, myxococcus xanthus. the fibrils are composed of a carbohydrate backbone and a set of five integral fibrillar proteins (ifps) ranging from 14 to 66 kda. as part of an attempt to understand the function(s) of the ifps, a mutant (ifp-1:20) was generated that lacks ifp-1:20, one of the fibril proteins, as shown by western blot analysis of both whole cells and isolated fibrils. unlike those of the parent ...	1997	9421894
a dnak homolog in myxococcus xanthus is involved in social motility and fruiting body formation.	myxococcus xanthus is a gram-negative soil bacterium which exhibits a complex life cycle and social behavior. in this study, two developmental mutants of m. xanthus were isolated through tn5 transposon mutagenesis. the mutants were found to be defective in cellular aggregation as well as in sporulation. further phenotypic characterization indicated that the mutants were defective in social motility but normal in directed cell movements. both mutations were cloned by a transposon-tagging method. ...	1998	9440508
myxococcus xanthus displays frz-dependent chemokinetic behavior during vegetative swarming.	myxococcus xanthus has been shown to utilize both directed (tactic) and undirected (kinetic) movements during different stages of its complex life cycle. we have used time-lapse video microscopic analysis to separate tactic and kinetic behaviors associated specifically with vegetatively swarming cells. isolated individual cells separated by a thin agar barrier from mature swarms showed significant increases in gliding velocity compared to that of similar cells some distance from the swarm. this ...	1998	9440539
genetic determinants of immunity and integration of temperate myxococcus xanthus phage mx8.	an 8.1-kb fragment of the temperate myxococcus xanthus phage mx8 genome, when cloned into a plasmid vector, permits site-specific integration of the plasmid and confers superinfection immunity. sequence analysis of a 9.5-kb region of mx8 dna containing this fragment reveals 19 densely packed open reading frames, four of which have predicted products with known or suspected activities. the mx8 imm gene, required for superinfection immunity, has a sequence similar to that of arabidopsis thaliana g ...	1998	9457865
contact stimulation of tgl and type iv pili in myxococcus xanthus.	myxococcus xanthus tgl mutants lack social motility and type iv pili but can be transiently stimulated to swarm and to make pili by contacting tgl+ cells. the absence of pili in tgl mutants is shown not to be due to the absence of pilin. the rate of pilus elongation after tgl stimulation is shown to be similar to the rate of pilus elongation in wild-type cells, using a new more rapid assay for stimulation.	1998	9457887
alignment enhances the cell-to-cell transfer of pilus phenotype.	social gliding motility of myxococcus xanthus requires polar type iv pili. tgl mutants lack pili and lack social motility. however, both defects can be rescued phenotypically, but not genotypically, when tgl+ donor and tgl- recipient cells make physical contact with each other. what is the cellular and molecular basis of this transfer of phenotype, which is called stimulation? stimulation does not occur in liquid nor in soft (0.5%) agar; however, on a more firm surface (1.0% agar) cells stimulat ...	1998	9501214
the guanosine nucleotide (p)ppgpp initiates development and a-factor production in myxococcus xanthus.	guanosine 3'-di-5'-(tri)di-phosphate nucleotides [(p)ppgpp], synthesized in response to amino acid limitation, induce early gene expression leading to multicellular fruiting body formation in myxococcus xanthus. a mutant (dk527) that fails to accumulate (p)ppgpp in response to starvation was found to be blocked in development prior to aggregation. by use of a series of developmentally regulated tn5lac transcriptional fusion reporters, the time of developmental arrest in dk527 was narrowed to wit ...	1998	9531539
identification of the omega4400 regulatory region, a developmental promoter of myxococcus xanthus.	omega4400 is the site of a tn5 lac insertion in the myxococcus xanthus genome 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 omega4400. the dna upstream of the omega4400 insertion has been cloned, the promoter has been localized, and a partial open reading frame has been identified. from the deduced amino acid sequence of the partial open reading frame, ...	1998	9555878
identification of an fad superfamily containing protoporphyrinogen oxidases, monoamine oxidases, and phytoene desaturase. expression and characterization of phytoene desaturase of myxococcus xanthus.	a large number of fad-containing proteins have previously been shown to contain a signature sequence that is referred to as the dinucleotide binding motif. protoporphyrinogen oxidase (ppo), the penultimate enzyme of the heme biosynthetic pathway, is an fad-containing protein that catalyzes the six electron oxidation of protoporphyrinogen ix. sequence analysis demonstrates the presence of the dinucleotide binding motif at the amino-terminal end of the protein. analysis of the current data base re ...	1998	9593705
bacterial motility: secretory secrets of gliding bacteria.	many bacteria glide over surfaces without the aid of flagella. gliding is still somewhat mysterious, but recent studies show that it involves specialized secretory systems that assemble membrane-associated filaments, and the recognition of extracellular components that trigger movement via transmembrane transducers.	1998	9637910
molecular analysis of the dna gyrb gene from myxococcus xanthus.	dna gyrase, an essential type ii topoisomerase, mediates negative supercoiling of the bacterial chromosome, thereby affecting the processes of dna replication, transcription, recombination and repair. the gyrb gene from the gram-negative soil bacterium myxococcus xanthus was sequenced. the sequence predicts a protein of 815 amino acid residues displaying significant homology to all known gyrb proteins. a 6-his-gyrb fusion protein was overexpressed in escherichia coli and purified to near homogen ...	1998	9639935
the extracytoplasmic function sigma factors: role and regulation.	alternative sigma factors provide a means of regulating gene expression in response to various extracellular changes. one such class of sigma factors appears to control a variety of functions, including expression of heat-shock genes in escherichia coli, biosynthesis of alginates and carotenoids in pseudomonas aeruginosa and myxococcus xanthus, respectively, iron uptake in e. coli and pseudomonas spp., nickel and cobalt efflux in alcaligenes europhus, plant pathogenicity in pseudomonas syringae ...	1998	9680198
propionyl-coa carboxylase of myxococcus xanthus: catalytic properties and function in developing cells.	an acyl-coenzyme a carboxylase that carboxylates acetyl-coa, butyryl-coa, propionyl-coa, and succinyl-coa was purified from myxococcus xanthus. since the enzyme showed maximal rates of carboxylation with propionyl-coa, the enzyme is thought to be propionyl-coa carboxylase. the apparent km values for acetyl-coa, butyryl-coa, propionyl-coa, and succinyl-coa were found to be 0.2, 0. 2, 0.03, and 1.0 mm, respectively. the native enzyme has a molecular mass of 605-615 kda and is composed of nonidenti ...	1998	9683657
mgla and mglb are required for the intramacrophage growth of francisella novicida.	francisella novicida is a facultative intracellular pathogen capable of growing in macrophages. a spontaneous mutant of f. novicida defective for growth in macrophages was isolated on lb media containing the chromogenic phosphatase substrate 5-bromo-4-chloro-3-indolyl phosphate (x-p) and designated gb2. using an in cis complementation strategy, four strains were isolated that are restored for growth in macrophages. a locus isolated from one of these strains complements gb2 for both the intracell ...	1998	9701818
pilt mutations lead to simultaneous defects in competence for natural transformation and twitching motility in piliated neisseria gonorrhoeae.	neisseria gonorrhoeae, the gram-negative aetiological agent of gonorrhoeae, is one of many mucosal pathogens of man that expresses competence for natural transformation. expression of this phenotype by gonococci appears to rely on the expression of type iv pili (tfp), but the mechanistic basis for this relationship remains unknown. during studies of gonococcal pilus biogenesis, a homologue of the pilt family of proteins, required for tfp-dependent twitching motility in pseudomonas aeruginosa and ...	1998	9701824
sdek is required for early fruiting body development in myxococcus xanthus.	myxococcus xanthus cells carrying the omega4408 tn5lac insertion at the sde locus show defects in fruiting body development and sporulation. our analysis of sde expression patterns showed that this locus is induced early in the developmental program (0 to 2 h) and that expression increases approximately fivefold after 12 h of development. further studies showed that expression of sde is induced as growing cells enter stationary phase, suggesting that activation of the sde locus is not limited to ...	1998	9721305
a new sigma factor, sigd, essential for stationary phase is also required for multicellular differentiation in myxococcus xanthus.	myxococcus xanthus is a gram-negative bacterium that undergoes spectacular development to form multicellular fruiting bodies under nutrient deprivation. inside a fruiting body, vegetative cells differentiate into spores. a number of sigma factors have been shown to play roles in the regulation of gene expression in the m. xanthus life cycle. additional sigma factors were searched to further explore the m. xanthus life cycle.	1998	9734783
myxococcus xanthus spore coat protein s, a stress-induced member of the betagamma-crystallin superfamily, gains stability from binding of calcium ions.	protein s, a calcium-binding spore coat protein from the soil bacterium myxococcus xanthus, belongs to a group of structurally related proteins, the betagamma-crystallin superfamily. common features of this protein family are the greek-key structural motif or crystallin fold, and the fact that all members are extremely stable long term. to investigate the correlation between the stability and greek-key topology, protein s was cloned, expressed in escherichia coli and purified to homogeneity. ca2 ...	1998	9738899
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 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
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 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
myxococcus xanthus biomass as biosorbent for lead.	this paper deals with lead biosorption by myxococcus xanthus biomass in which dry biomass, accumulating up to 1.28 mmol of lead g(-1), is demonstrated to be a more efficient biosorbent than wet biomass. dry biomass biosorption was found to be very rapid, reaching equilibrium after 5-10 min. culture age, the initial lead concentration and ph affected this process, but temperature did not. furthermore, by using sodium citrate as a desorbent agent, 92.17% of the biosorbed lead could be recovered. i ...	1998	15244058
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
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
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