Publications

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mode of insertion of the broad-host-range plasmid rp4 and its derivatives into the chromosome of myxococcus xanthus.the mode of insertion of the broad-host-range plasmid rp4 into the chromosome of myxococcus xanthus strain dz1 has been analyzed. the plasmid integrated in numerous sites of the chromosome and generated insertional mutations. there is a hot spot of integration located between 31.5 and 34.5 kb clockwise from the ecori site of the plasmid. in the absence of this segment the insertion can, however, take place, but much less efficiently. the presence of transposable elements on the plasmid decreases ...19872829249
comparison of the phosphatases of lysobacter enzymogenes with those of related bacteria.lysobacter enzymogenes atcc 29487 (uasm 495) produces an outer-membrane-associated phosphatase and an excreted phosphatase. the cell-associated enzyme was compared to phosphatases of nine other gram-negative gliding bacteria and to that of escherichia coli. the other three species of the genus lysobacter also produce a particulate, cell-associated phosphatase. antiserum prepared against the phosphatase from the outer membrane of l. enzymogenes effectively precipitated the phosphatases of two oth ...19872833562
identification of the rna products of the ops gene of myxococcus xanthus and mapping of ops and tps rnas.the expression of the ops gene, like that of the highly homologous and closely linked tps gene, is induced during development of the fruiting bacterium myxococcus xanthus. the rna products of the ops gene have been identified and compared with tps rna. the ops rna was observed in developmental cells only after spore formation had commenced, and it was necessary to use a sporulation-defective mutant strain or to disrupt spores to isolate this rna. rna from the ops gene was not observed in vegetat ...19872435705
structure of msdna from myxococcus xanthus: evidence for a long, self-annealing rna precursor for the covalently linked, branched rna.the branched rna (msdrna) of m. xanthus consists of 77 bases. the 20th rg residue is linked to the 5' end of msdna, consisting of 162 bases, by a 2', 5' phosphodiester linkage. the msdrna coding region is located on the chromosome in the opposite orientation to the msdna coding region, with the 3' ends overlapping by eight bases. s1 nuclease mapping experiments indicate that the primary product of msdrna is much longer at both the 5' and 3' ends (approximately 375 bases). because of homologous s ...19872446773
a new species of multicopy single-stranded dna from myxococcus xanthus with conserved structural features.myxobacteria have been shown to contain a large number of branched rna-linked single-stranded dna (multicopy single-stranded dna (msdna] molecules. in addition, we found that myxococcus xanthus contains another smaller msdna-like molecule, designated mrdna, consisting of a 65-base single-stranded dna covalently linked by a 2',5'-phosphodiester linkage to a 49-base branched rna. in spite of their different primary sequences, the rna-linked mrdna is remarkably similar in secondary structure to msd ...19882454233
saframycin mx1, a new natural saframycin isolated from a myxobacterium.a new natural saframycin was discovered in the culture broth of the myxobacterium, myxococcus xanthus strain mx x48. the fermentation and isolation of the antibiotic are described. the name, saframycin mx1, is proposed. the compound appears to interact with cellular dna.19882459096
mutations that affect production of branched rna-linked msdna in myxococcus xanthus.a deletion mutation of the gene (msd-msr) for the branched rna-linked msdna of myxococcus xanthus was constructed by replacing the chromosomal 0.7-kilobase (kb) smai-xhoi fragment encompassing msd-msr with a 1.4-kb fragment carrying a gene for kanamycin resistance. it was found that this deletion strain (delta mssx) could not produce msdna, although it still contained another species of msdna, mrdna (msdna, reduced size). no apparent differences between delta mssx and the wild-type strain were o ...19882461359
tn5-mediated transposition of plasmid dna after transduction to myxococcus xanthus.after coliphage p1-mediated transfer of tn5-containing plasmid dna from escherichia coli to myxococcus xanthus, transductants were identified which contained plasmid sequences integrated at many sites on the bacterial chromosome. the unaltered plasmid dna sequences in these transductants were apparently flanked by intact tn5 or is50 sequences. these results suggest that tn5-mediated transposition has occurred and provide a method for integrating plasmid dna into the m. xanthus chromosome without ...19882844730
genetic identification and cloning of a gene required for developmental cell interactions in myxococcus xanthus.developmental mutants of myxococcus xanthus have been previously described which appear to be defective in required cell-cell interactions. these mutants fall into four phenotypic classes, asg, bsg, csg, and dsg, each of which is unable to differentiate into spores but can be rescued by extracellular complementation by wild-type cells or by mutants of a different class. we report the identification of one of the loci in which mutations result in a bsg phenotype. the cloned locus was contained on ...19882846514
identification and characterization of the myxococcus xanthus bsga gene product.the bsga mutants of myxococcus xanthus are blocked at a very early stage of the developmental program. they fail to produce fruiting bodies or to sporulate under normal conditions but can be rescued by extracellular complementation in mixtures with wild-type cells. a bsga-lacz gene fusion was constructed and expressed in escherichia coli. the resulting fusion protein, which has beta-galactosidase enzyme activity, was partially purified by affinity chromatography and preparative polyacrylamide ge ...19882846515
utilization of incp-1 plasmids as vectors for transposon mutagenesis in myxobacteria.no free plasmid has ever been found in the myxobacterium myxococcus xanthus, but incp-1 plasmids are able to integrate into the chromosome of this bacterium. the frequency of integration depends greatly upon the structure of the incp-1 plasmid used. this property has been used to devise new delivery systems for transposon mutagenesis in this species. plasmids with low integration efficiencies have proved to be efficient donors of tn5, while plasmids with very high frequencies of integration coul ...19882855525
use of recombination techniques to examine the structure of the csg locus of myxococcus xanthus.the myxobacteria are among the simplest organisms with a developmental cycle that is dependent on cell cooperation, and they provide an outstanding system with which to study genes involved in cell interactions. myxococcus xanthus cells which acquire a csg mutation (formerly known as spoc) lose three different traits, the ability to sporulate, the ability to stimulate adjacent csg cells to sporulate, and the ability to ripple. the boundaries of the csg locus were determined by transferring a rec ...19882830469
characterization of calcium-binding sites in development-specific protein s of myxococcus xanthus using site-specific mutagenesis.protein s, the most abundant protein synthesized during development of the gram-negative bacterium myxococcus xanthus, assembles on the surface of the spores. it can be dissociated from the spores using divalent metal chelators and will reassemble on the spores in the presence of calcium. the amino acid sequence of protein s contains regions which have homology to the calcium-binding sites of calmodulin. protein s was found to bind 2 mol of calcium/mol of protein with kd values of 27 and 76 micr ...19883121626
novel macrocyclic antibiotics: megovalicins a, b, c, d, g and h. i. screening of antibiotics-producing myxobacteria and production of megovalicins.new antibiotics belonging to macrocyclic were discovered and named megovalicins a, b, c, d, g and h. the antibiotics were accumulated endogeneously by a newly isolated myxobacterium identified as myxococcus flavescens. tank culture of the bacterium for 4 days gave 8.8 g cells/liter on a wet basis, and 4.8, 7.1, 20.0, 0.4, 3.75 and 15.0 micrograms of megovalicins a, b, c, d, g and h respectively were obtained from 1 g wet cells.19883131289
novel macrocyclic antibiotics: megovalicins a, b, c, d, g and h. ii. isolation and chemical structures of megovalicins.myxococcus flavescens aj12298 was found to produce the complex of macrocyclic antibiotics named megovalicins. the physico-chemical studies revealed that megovalicins c and b were identical to myxovirescin a1 and antibiotic m-230b, respectively, and that megovalicins a, d, g and h were closely related new antibiotics.19883131290
reexamination of the role of autolysis in the development of myxococcus xanthus.it has been widely reported that 80 to 90% of the cell population undergoes autolysis during sporulation in myxococcus xanthus. a re-evaluation of the techniques used to measure autolysis in m. xanthus showed that the methods previously used to draw this conclusion are subject to artifacts, which result in a substantial underestimation of the number of cells present during development. we found that at least 80% of the cells that enter development survive throughout fruiting body formation. the ...19883137213
localization of the cis-acting regulatory dna sequences of the myxococcus xanthus tps and ops genes.the cis-acting regulatory regions of the tps and ops genes of myxococcus xanthus were localized by analyzing the expression of fusions of these genes with the lacz gene. a 201-base-pair (bp) fragment of tps dna extending 95 bp upstream (-95) from the transcriptional start was sufficient to direct developmentally regulated expression of fusion gene activity. the segment of tps dna between -95 and -81 contained information necessary for developmental regulation. a segment of ops dna extending upst ...19883139640
acceleration of starvation- and glycerol-induced myxospore formation by prior heat shock in myxococcus xanthus.the effect of heat shock on myxococcus xanthus was investigated during both glycerol- and starvation-induced development. cells heat shocked at 40 degrees c for 1 h prior to a development-inducing signal displayed an accelerated rate of myxospore formation at 30 degrees c. additionally, m. xanthus cells heat shocked prior to glycerol induction formed a greater total number of myxospores when sporulation was complete than did control cells maintained at 30 degrees c. however, in starvation-induce ...19883141380
an extracellular blood-anticoagulant glycopeptide produced exclusively during vegetative growth by myxococcus xanthus and other myxobacteria is not co-regulated with other extracellular macromolecules.we have shown that the blood anticoagulant activity (baa) secreted by myxococcus xanthus (designated myxaline) is a heat-stable molecule; a high-molecular-mass extracellular fraction also with an apparent baa is a thermolabile protease. this property allowed us to assay the baa content in crude boiled culture supernatants and to study the conditions under which it is produced. heat-stable baa is strictly extracellular and its production is restricted to vegetative growth in m. xanthus. unlike th ...19883141577
site-specific integration and expression of a developmental promoter in myxococcus xanthus.a series of intercellular signals are involved in the regulation of gene expression during fruiting body formation of myxococcus xanthus. mutations which block cell interactions, such as csga (formerly known as spoc), also prevent expression of certain developmentally regulated promoters. csga+ cells containing tn5 lac omega dk4435, a developmentally regulated promoter fused to lacz, began synthesizing lacz mrna 12 to 18 h into the developmental cycle. beta-galactosidase specific activity increa ...19883142850
inhibition of cell-cell interactions in myxococcus xanthus by congo red.the function of molecules associated with the cell surface may be determined by examining the phenotype of cells treated with inhibitors specific to these cell surface molecules. this strategy was used to examine the function of the major congo red receptor of the myxobacterium myxococcus xanthus, which has a developmental cycle that involves social interactions among cells. a class of social motility mutations (a+ s-), known as dsp, may inhibit the same subcellular component as congo red becaus ...19883142856
cell surface properties correlated with cohesion in myxococcus xanthus.the gliding behavior of myxococcus xanthus cells is controlled by two multigene systems, a and s, which encode information for adventurous and social behaviors, respectively. the s system can be genetically disrupted through mutation, such as a dsp mutation, or phenotypically disrupted by treating cells with the diazo dye congo red (arnold and shimkets, j. bacteriol. 170:5765-5770, 1988). one of the functions controlled by the s system is cell agglutination. immediately after the induction of ag ...19883142857
isolation of additional monoclonal antibodies directed against cell surface antigens of myxococcus xanthus cells undergoing submerged development.thirteen additional monoclonal antibodies directed against cell surface antigens of myxococcus xanthus cells undergoing submerged development were isolated and partially characterized. as measured by quantitative enzyme-linked immunosorbent assay, 10 of these antibodies recognized antigens common to both vegetatively growing cells and cells undergoing submerged development; 3 antibodies recognized antigens specific to developing cells. five antigens were revealed as single bands on western blots ...19883142865
a link between cell movement and gene expression argues that motility is required for cell-cell signaling during fruiting body development.nonmotile mutants of myxococcus xanthus (myxobacterales) failed to execute the morphogenetic movements required to shape a fruiting body. in addition, nonmotile mutants produced very few spores when plated for fruiting body development at cell densities appropriate for wild-type cells. at higher initial cell densities, the proportion of nonmotile cells that sporulate increased, indicating that one important function of motility in fruiting body development is to increase the local cell density. ...19883145903
antibiotic ta--a new adherent agent for the treatment of periodontal disease. 19883271636
effect of adhesive antibiotic ta on plaque and gingivitis in man.the adhesive antibiotic ta was applied to the dento-gingival junction of 8 human volunteers, suffering from moderate to severe gingivitis. 2 diametrically opposed quadrants of the mouth received 4 applications of 0.1 mg ta, while the other 2 quadrants were treated with a placebo and served as controls. the plaque index, gingival index and bleeding index were scored periodically for 2 weeks and in 4 patients for up to 30 days. the ta-treated quadrants showed a rapid decrease in all 3 indices foll ...19892613931
interference reflection microscopic study of sites of association between gliding bacteria and glass substrata.sites of close contact between gliding cytophaga sp. strain u67 cells and glass were examined by interference reflection microscopy. site patterns changed during translocation and moved relative to the substratum, in contrast to previous interference reflection microscopy observations of fibroblast and amoeboid motility. sinistral rotation around the long axis of the cell was coupled with gliding, except when curved cells traversed curvilinear pathways. close contact was temporary, since cells f ...19892768185
gliding motility in myxococcus xanthus: mgl locus, rna, and predicted protein products.mutants of myxococcus xanthus that had lost the ability to glide were examined to elucidate the mechanism of gliding motility. nonmotile mutants resulting from a single mutational step were all defective at the same locus, mgl, which implied an important role for the mgl product(s) in gliding. deletion experiments, transposon insertion mutagenesis, and genetic rescue of mgl mutants mapped the locus to a 1.6-kilobase segment of myxococcus dna. two species of rna that hybridized with mgl dna were ...19892464581
reverse transcriptase with concomitant ribonuclease h activity in the cell-free synthesis of branched rna-linked msdna of myxococcus xanthus.msdna is a peculiar molecule consisting of a branched rna linked to single-stranded dna via a 2',5' phosphodiester bond. a cell-free system, utilizing cells permeabilized with phenethyl alcohol, was established to study the synthesis of msdna in m. xanthus. permeablized cells labeled with [alpha-32p]dctp in the presence of ddgtp, ddatp, or ddttp produce a band that migrates at the same position as the full-sized msdna in an polyacrylamide gel. however, when this band is treated with ribonuclease ...19892465091
reverse transcriptase associated with the biosynthesis of the branched rna-linked msdna in myxococcus xanthus.myxobacteria have been shown to produce a peculiar rna-dna complex called msdna, in which a single-stranded dna is branched out from a rna molecule (msdrna) by a 2',5' phosphodiester linkage. it has been predicted that reverse transcriptase is required for msdna biosynthesis. we identified a gene for reverse transcriptase in m. xanthus in the region that has been demonstrated to code for a cis- or transacting element for msdna synthesis. this gene is located immediately downstream of the msdrna ...19892465092
structural requirements of the rna precursor for the biosynthesis of the branched rna-linked multicopy single-stranded dna of myxococcus xanthus.a precursor rna molecule (pre-msdrna) of approximately 375 bases is considered to form a stable secondary structure which serves as a primer as well as a template to synthesize the branched rna-linked multicopy single-stranded dna (msdna) of myxococcus xanthus. when 3-base mismatches were introduced into the stem structure immediately upstream of the branched rg residue to which msdna is linked by a 2',5'-phosphodiester linkage, the production of msdna was almost completely blocked. however, if ...19892467910
purification and properties of myxococcus xanthus cell surface antigen 1604.a cell surface antigen complex from zwittergent-solubilized myxococcus xanthus has been purified by immunoaffinity chromatography with monoclonal antibody (mab) 1604 and by subsequent gel filtration. we propose that the cell surface antigen (csa) 1604 complex participates in intercellular interactions. the apparent total molecular mass of the csa 1604 complex is 200 kilodaltons (kda), as determined by gel filtration and by electrophoresis and western immunoblot probing with mab 1604. the antigen ...19892475480
"frizzy" aggregation genes of the gliding bacterium myxococcus xanthus show sequence similarities to the chemotaxis genes of enteric bacteria.the frz genes of myxococcus xanthus are necessary for proper aggregation of cells to form fruiting bodies. mutations in the frz genes affect the frequency with which individual cells reverse their direction of movement. we have subcloned and determined the nucleotide sequence of three of the frz genes. from the sequence we predict three open reading frames corresponding to frza, frzb, and frzcd. the putative frza protein (17,094 da) exhibits 28.1% amino acid identity with the chew protein of sal ...19892492105
autocide ami rescues development in dsg mutants of myxococcus xanthus.low concentrations of autocide ami rescued aggregation and sporulation in the dsg mutant class of myxococcus xanthus but were incapable of rescuing asg, bsg, or csg mutants. ami-induced spores of dsg mutants were resistant to heat and sonication and germinated when plated on nutrient-rich agar. ami accelerated aggregation and sporulation and increased the final spore number in submerged cultures of a wild-type strain of m. xanthus. development of m. xanthus was accompanied by release of a fluore ...19892493446
novel change in the carbohydrate portion of myxococcus xanthus lipopolysaccharide during development.we have examined the alterations in lipopolysaccharide during aggregation and early development in myxococcus xanthus. the lipopolysaccharide was isolated and characterized from cells developing on agar during glycerol induction and vegetative growth. a methylated amino sugar was identified as 6-o-methylgalactosamine by gas-liquid chromatography-mass spectrometry. this novel sugar was enriched in cells developing on agar.19892495265
characterization of lipopolysaccharide from myxococcus xanthus by use of monoclonal antibodies.lipopolysaccharide is a major constituent of the cell surface of the gram-negative procaryote myxococcus xanthus. we have purified lipopolysaccharide from m. xanthus and have shown by silver staining that the lipopolysaccharide contains a heterogeneous population of molecules which migrate as a broad low-molecular-mass band (approximately 5 kilodaltons) and as a stepladder of about 30 higher-molecular-mass bands (15- to 70-kilodalton range). the broad band consists of lipopolysaccharide molecule ...19892495269
defects in motility and development of myxococcus xanthus lipopolysaccharide mutants.five transposon tn5 mutants of the procaryote myxococcus xanthus had been shown previously to be defective in lipopolysaccharide biosynthesis (j. m. fink,-m. kalos, and j. f. zissler, j. bacteriol. 171:2033-2041, 1989). these mutants were studied for possible defects in gliding motility and multicellular development. wild-type m. xanthus cells glide both as single cells and as groups of cells. we found that the tn5 lipopolysaccharide o-antigen mutants were defective in single-cell motility but w ...19892495270
bactericidal and bacteriolytic action of peptide antibiotic as-48 against gram-positive and gram-negative bacteria and other organisms.a purified peptide antibiotic as-48 from streptococcus faecalis spp liquiefaciens s-48 exerted a bactericidal mode of action against most gram-positive and many gram-negative bacteria tested. in many gram-positive bacteria and the two myxococcus species assayed, a bacteriolytic effect, as a consequence of primary lesions, was also observed. in general, the gram-negative bacteria were more resistant to as-48. escherichia coli protoplasts showed increased sensitivity and those of a resistant yeast ...19892501837
sporulation of myxococcus xanthus in liquid shake flask cultures.when suspended in a liquid starvation medium, exponentially growing myxococcus xanthus sporulated within 3 days. these myxospores were similar to spores developed within fruiting bodies, as determined by electron microscopy and the production of spore-specific protein s. this liquid sporulation system may be useful as a means of preparing large quantities of myxospores and extracellular fluid for biochemical studies, including isolation of chemical signals produced during the sporulation process ...19892502539
myxococcus xanthus msdna.mx162 exists as a complex with proteins.myxococcus xanthus, a myxobacterium, contains a peculiar branched rna-linked dna called msdna. reverse transcriptase has been shown to be required for the production of msdna. existence of proteins that bind to one of the two msdnas in m. xanthus, msdna.mx162, was examined by gel retardation assays. total cell-free extract yielded two distinct retarded bands. both bands were sensitive to treatment with proteinase k, indicating that there is a protein(s) that is able to bind to msdna. further, th ...19892503505
role of myxococcus xanthus cell surface antigen 1604 in development.the inhibition of development of myxococcus xanthus by monoclonal antibody (mab) 1604 has been further investigated with two mabs produced against the affinity-purified cell surface antigen (csa) 1604. both of these second-generation mabs, 4070 and 4054, reacted with the same band at 150 kilodaltons (kda) on western immunoblots of lysed and reduced cells. this band was also identified by mab 1604. however, the affinity-purified csa was a complex of the two proteins (51 and 23 kda) and lipopolysa ...19892504693
cell-density-dependent lysis and sporulation of myxococcus xanthus in agarose microbeads.vegetative cells of myxococcus xanthus were immobilized in 25-microns-diameter agarose microbeads and incubated in either growth medium or sporulation buffer. in growth medium, the cells multiplied, glided to the periphery, and then filled the beads. in sporulation buffer, up to 90% of the cells lysed and ca. 50% of the surviving cells formed resistant spores. a strong correlation between sporulation and cell lysis was observed; both phenomena were cell density dependent. sporulation proficiency ...19892504696
production of acid and alkaline phosphatases by myxococcus coralloides.acid and alkaline phosphatase of myxococcus coralloides were examined during vegetative growth in a liquid medium. two extracellular phosphatases and two cell-bound phosphatases, acid and alkaline in both cases, were produced. the phosphatase production was unaltered by the presence of high concentrations of inorganic phosphate. both enzymes were produced constitutively. these two hydrolases were released into the growth medium during the exponential growth phase (approximately 10% of total acti ...19892509312
patterns of cellular interactions during fruiting-body formation in myxococcus xanthus.aggregation and mound formation during development of the myxobacterium myxococcus xanthus were examined by scanning electron microscopy and light microscopy. several complex patterns of multicellular associations were observed. these observations imply that complex, organized cell-cell interactions occur during the process of development. examination of sliced aggregates revealed that, contrary to common perception, the process of sporulation commenced during mound formation rather than after t ...19892509425
calcium requirement for gliding motility in myxobacteria.the ability to glide on a solid surface was inducible by calcium ion in stigmatella aurantiaca. the induction of motility but not motility itself was prevented by chloramphenicol and erythromycin. calcium ion was also required for cells to glide, even when they were previously induced. the ability of myxococcus xanthus to glide in groups using the s motility system but not as single cells (a system) was prevented by chloramphenicol and erythromycin.19892509428
trehalose accumulation in vegetative cells and spores of myxococcus xanthus.the disaccharide trehalose is found in the spores and cysts of a variety of organisms. we analyzed developing cells of myxococcus xanthus for trehalose accumulation. vegetative cells grown in media with low osmotic strengths contained less than 5 micrograms of trehalose per mg of protein. spores formed in fruiting bodies accumulated up to 1,100 micrograms of trehalose per mg of protein. spores formed in liquid culture following the addition of glycerol contained up to 300 micrograms of trehalose ...19892509436
physical mapping of the myxococcus xanthus genome by random cloning in yeast artificial chromosomes.random segments of myxococcus xanthus dna were cloned in yeast artificial chromosomes (yacs) to construct a physical map of the genome. ecori restriction maps of 409 yac clones with inserts averaging 111 kilobase pairs (kb) were determined. comparison to the map of a 300-kb region of m. xanthus obtained from clones in escherichia coli indicates that segments of dna cloned in yacs are stably maintained in yeast and that their sequences accurately reflect the structure of the myxococcus genome. th ...19892510171
isolation of cell surface antigen mutants of myxococcus xanthus by use of monoclonal antibodies.monoclonal antibodies (mabs) with affinities for molecules on the cell surface of the procaryote myxococcus xanthus were used in a screening strategy for the isolation of mutants lacking particular cell surface molecules. from a large library of independent mutants created by tn5 transposon mutagenesis, mutants were isolated which lacked reactivities with mab 1604 (a mab specific for a cell surface protein) and mabs 2600, 1733, 1514, 1412, and 783 (mabs specific for carbohydrate epitopes on the ...19892539357
movement of multiple dna units between myxococcus xanthus cells.myxococcus xanthus ys produces particles (mx alpha particles) that transmit genetic information between cells. mx alpha particles might be viruses, although no host able to sustain lytic growth of mx alpha has been discovered. the particles could be detected by their ability to transduce a tn5 transposon tag to recipient bacteria. dna from purified particles hybridized to a limited number of dna restriction fragments of strain ys, suggesting that mx alpha particles contain only specific dna sequ ...19892540147
genes required for developmental signalling in myxococcus xanthus: three asg loci.asg-carrying strains of myxococcus xanthus arose in a selection for mutants defective in cell-cell signalling during fruiting body development. all 15 asg mutations examined were found to lie in one of three genetic loci, asga, asgb, or asgc. the loci were defined by linkage to different insertions of transposon tn5 and molecular cloning of asga. asg mutants of all three types were deficient in the aggregation of cells into mounds of the sort that normally give rise to fruiting bodies. asg mutan ...19892540156
developmental bypass suppression of myxococcus xanthus csga mutations.the csga mutations of myxococcus xanthus (formerly known as spoc) inhibit sporulation as well as rippling, which involves ridges of cells moving in waves. sporulating revertants of csga cells were isolated by direct selection, since spores are much more resistant to heat and ultrasonic treatment than are vegetative cells. the revertants fell into seven groups on the basis of phenotype and the chromosomal location of the suppressor alleles. group 1 contained one allele that was a back mutation of ...19892542221
dsg, a gene required for cell-cell interaction early in myxococcus development.dsg mutants of myxococcus xanthus are conditionally defective in fruiting body development, including sporulation. unable to develop on their own, these mutants can assemble fruiting bodies with spores if they are mixed with wild-type cells. to elucidate the developmental defect in dsg mutants by close comparison with wild type, such mutants have been backcrossed by transduction, using a closely linked insertion of transposon tn5 for selection. backcrossed dsg mutants form aggregates that are la ...19892544552
dsg, a gene required for myxococcus development, is necessary for cell viability.previous work identified the dsg gene as necessary for cell-cell interaction in myxococcus xanthus. point mutations of this gene, such as dsg-439, are viable, but insertions of tn5 within the dsg gene (dsg::tn5) are lethal. partial diploids, dsg::tn5/dsg+ or dsg::tn5/dsg-429 or dsg::tn5/dsg-439, are also viable, showing that the lethal effect of the haploid insertions is due to loss of function. thus the evidence implies that the dsg gene is essential for viability as well as development, but it ...19892544553
evidence that the myxococcus xanthus frz genes are developmentally regulated.the frizzy (frz) mutants of myxococcus xanthus are unable to form fruiting bodies. instead of forming discrete mounds, these strains aggregate as filaments which have a circular and tangled appearance. mutations leading to this phenotype have been mapped to five complementation groups, frza, frzb, frzcd, frze, and frzf. all have been found to be involved in the control of directional movement of the bacteria and, except for frzb, to be homologous to the chemotaxis genes of enteric bacteria. in t ...19892553673
asgb, a gene required early for developmental signalling, aggregation, and sporulation of myxococcus xanthus.the asgb genetic locus of myxococcus xanthus specifies a function which is required early in the developmental pathway leading to aggregation and sporulation in fruiting bodies. the developmental defect of asgb mutants can be compensated by extracellular complementation using either intact wild-type cells or cell-free supernatants conditioned by developing wild-type cells. a tn5 insertion was isolated closely linked to asgb480 and facilitated the cloning of both the wild-type (asgb+) and the mut ...19892555667
genic and allelic interactions in the carotenogenic response of myxococcus xanthus to blue light.in the bacterium myxococcus xanthus, the synthesis of carotenoids requires illumination with blue light. this stimulates transcription of the carb locus, which is positively required for carotenogenesis. mutations at the carr locus and the only mutation known at cara cause constitutive expression of carb and thus remove the light requirement for carotenoid accumulation (car(c) phenotype). the carr locus is unlinked, and cara is linked, to carb. we have now identified a novel class of car mutatio ...198917246505
microfossils from silicified stromatolitic carbonates of the upper proterozoic limestone-dolomite 'series', central east greenland.silicified flake conglomerates and in situ stratiform stromatolites of the upper proterozoic (c. 700-800 ma) limestone-dolomite 'series', central east greenland, contain well preserved microfossils. five stratigraphic horizons within the 1200 m succession contain microbial mat assemblages, providing a broad palaeontological representation of late proterozoic peritidal mat communities. comparison of assemblages demonstrates that the taxonomy and diversity of mat builder, dweller, and allochthon ...198911538669
effect of phosphate on antibiotic and extracellular protein production by myxococcus coralloides d.the effect of inorganic phosphate concentrations on antibiotic and extracellular protein production by myxococcus coralloides d have been examined. antibiotic production by growing cells of this myxobacterium was maximal at phosphate concentrations of 10-20 mm, but was inhibited by concentrations higher than 20 mm. the total extracellular protein and the extracellular protein per cell ratio were independent of phosphate levels in the culture broth.19901367446
purification and properties of a new restriction endonuclease, mxai, from myxococcus xanthus f18e. 19901369313
two independent retrons with highly diverse reverse transcriptases in myxococcus xanthus.a reverse transcriptase (rt) was recently found in myxococcus xanthus, a gram-negative soil bacterium. this rt has been shown to be associated with a chromosomal region designated a retron responsible for the synthesis of a peculiar extrachromosomal dna called msdna (multicopy single-stranded dna). we demonstrate that m. xanthus contains two independent, unlinked retrons, one for the synthesis of msdna-mx162 and the other for msdna-mx65. the structural analysis of the retron for msdna-mx65 revea ...19901689062
a segment of myxococcus xanthus ops dna functions as an upstream activation site for tps gene transcription.a segment of dna located between 131 and 311 base pairs (bp) upstream from the transcriptional start of the myxococcus xanthus ops gene (-131 to -311) was shown to function as an upstream activation site (uas) for developmentally regulated transcription from the tps gene promoter region. the activation of early developmental transcription by the ops uas was independent of orientation and could be increased by the addition of a second copy of the uas. the ops uas segment continued to function whe ...19901693144
cloning and dna sequence of the gene coding for the major sigma factor from myxococcus xanthus.the gene for a sigma factor (rpod) was cloned from myxococcus xanthus, a soil bacterium which differentiates to form fruiting bodies upon starvation for nutrients. the dna sequence of the gene was determined, and an open reading frame encoding a polypeptide of 708 amino acid residues (mr = 80,391) was identified. except for the amino-terminal sequence consisting of 100 residues, the m. xanthus sigma factor (sigma-80) showed extensive similarity with escherichia coli sigma-70 as well as bacillus ...19902104614
evolution of a protein superfamily: relationships between vertebrate lens crystallins and microorganism dormancy proteins.a search of sequence databases shows that spherulin 3a, an encystment-specific protein of physarum polycephalum, is probably structurally related to the beta- and gamma-crystallins, vertebrate ocular lens proteins, and to protein s, a sporulation-specific protein of myxococcus xanthus. the beta- and gamma-crystallins have two similar domains thought to have arisen by two successive gene duplication and fusion events. molecular modeling confirms that spherulin 3a has all the characteristics requi ...19902107329
c-factor: a cell-cell signaling protein required for fruiting body morphogenesis of m. xanthus.during fruiting body development, the product of the csga gene is necessary for cellular aggregation, for spore differentiation, and for gene expression that is initiated after 6 hr of starvation. from nascent wild-type fruiting bodies we have purified a polypeptide of 17 kd called c-factor, which, at approximately 1 to 2 nm, restores normal development to csga mutant cells. c-factor activity is not recovered from extracts of unstarved, growing cells or csga mutant cells. the amino acid sequence ...19902107980
purification and properties of myxococcus xanthus c-factor, an intercellular signaling protein.c-factor, a myxococcus xanthus protein that restores the developmental defects of a class of nonautonomous mutants resulting from mutation of the csga gene, has been purified approximately 1000-fold from starved wild-type cells. the monomeric form of c-factor is a single polypeptide with a molecular mass of 17 kda that can be solubilized by detergent from membrane components. characterization by gel filtration and denaturing gel electrophoresis suggests that biologically active c-factor is a dim ...19902111012
cell motility is required for the transmission of c-factor, an intercellular signal that coordinates fruiting body morphogenesis of myxococcus xanthus.there are striking similarities between the developmental phenotypes of two different mutant classes of myxococcus xanthus. the first class, mgla mutants, are nonmotile under all conditions tested. the second class, csga mutants, are motile but belong to a class of signal-defective developmental mutants that cannot develop alone but will develop when mixed with intact wild-type cells. nevertheless, both csga and mgla mutants fail to aggregate properly or to sporulate when induced to form fruitin ...19902116988
cell alignment required in differentiation of myxococcus xanthus.during fruiting body morphogenesis of myxococcus xanthus, cell movement is required for transmission of c-factor, a short range intercellular signaling protein necessary for sporulation and developmental gene expression. nonmotile cells fail to sporulate and to express c-factor-dependent genes, but both defects were rescued by a simple manipulation of cell position that oriented the cells in aligned, parallel groups. a similar pattern of aligned cells normally results from coordinated recruitmen ...19902118274
csga, an extracellular protein essential for myxococcus xanthus development.csga mutants of myxococcus xanthus appear to be defective in producing an extracellular molecule essential for the developmental behaviors of this bacterium. the csga gene encodes a 17.7-kilodalton polypeptide whose function and cellular location were investigated with immunological probes. large quantities of the csga gene product were obtained from a lacz-csga translational gene fusion expressed in escherichia coli. the chimeric 21-kilodalton protein was purified by preparative sodium dodecyl ...19902118510
comparison of beta-galactosidase production by two inducible promoters in myxococcus xanthus.the inducibility of two promoter systems, one heterologous and one homologous, has been assessed in the gram-negative bacterium myxococcus xanthus. the heterologous system involved the hybrid tac promoter and the presence of laciq, the lac repressor from escherichia coli. this system is inducible in its natural host with isopropyl-beta-d-thiogalactopyranoside (iptg). the homologous promoter system involves the light-inducible carqrs promoter, which is normally involved in the expression of the r ...19902119047
mechanism of integration of the broad-host-range plasmid rp4 into the chromosome of myxococcus xanthus.the site-specific recombination mechanism through which the plasmid rp4 has been previously shown to integrate into the chromosome of myxococcus xanthus has been investigated further. once integrated in one of the numerous chromosomal sites from two different strains, through a precise site on the plasmid, the latter can be excised either precisely or after a definite 14.5-kb deletion. in some cases, the integration is followed by different dna rearrangements that yield a higher rate of excision ...19902120716
development-specific sigma-factor essential for late-stage differentiation of myxococcus xanthus.the gene for a developmentally expressed sigma-factor, sigb, has been isolated from myxococcus xanthus by use of the siga gene (formerly rpod) of the vegetative sigma-factor as a probe. the sequence of sigb has been determined, and an open reading frame of 193 amino acid residues (mr = 21,551) was identified. the amino-terminal region of sigb contains 69 residues, of which 35 are identical (50% identity) to the region of siga required for core rna polymerase binding and initiation of rna polymer ...19902121605
accumulation of carotenoids in structural and regulatory mutants of the bacterium myxococcus xanthus.accumulation of carotenoids in myxococcus xanthus is absolutely dependent on illumination with blue light. we report the analysis of the carotenoids of dark- and light-grown cultures of the wild type and several previously characterized mutants. a carr mutant produces the same carotenoids in the dark as the wild type grown in the light. this agrees with previous evidence indicating that the carr gene codes for a general negative regulator of the system. a cis-dominant mutation in the gene cara c ...19902123519
purification and characterization of the myxococcus xanthus frze protein shows that it has autophosphorylation activity.myxococcus xanthus exhibits multicellular interactions during vegetative growth and fruiting body formation. gliding motility is needed for these interactions. the frizzy (frz) genes are required to control directed motility. frze is homologous to both chea and chey from salmonella typhimurium. we used polyclonal antiserum raised against a fusion protein to detect frze in m. xanthus extracts by western immunoblot analysis. frze was clearly present during vegetative growth and at much lower level ...19902123853
5s rrna sequences of myxobacteria and radioresistant bacteria and implications for eubacterial evolution.5s rrna sequences were determined for the myxobacteria cystobacter fuscus, myxococcus coralloides, sorangium cellulosum, and nannocystis exedens and for the radioresistant bacteria deinococcus radiodurans and deinococcus radiophilus. a dendrogram was constructed by using weighted pairwise grouping based on these and all other previously known eubacterial 5s rrna sequences, and this dendrogram showed differences as well as similarities compared with results derived from 16s rrna analyses. in the ...19902125831
anticoagulant activity of a bacterial glycopeptide.the anticoagulant properties of myxalin, a glycopeptide secreted by a gram negative bacterium strain (myxococcus xanthus) are studied and compared to those of heparin. this soluble material exhibits an anticoagulant activity which implies the inhibition of some serine proteases, thrombin and factor xa. in the presence of normal and antithrombin iii-depleted plasma, myxalin inhibits the amidolytic activity of thrombin on synthetic chromogenic substrate as a function of its concentration, but fail ...19902126150
modification of immune response by coats of myxococcus xanthus myxospores.treatment with coats of m. xanthus myxospores produced a marked modificatory effect on humoral response, depending on the inoculation model. also we observed that the percentage of adherent phagocytes and phagocytic index were enhanced after treatment. these results were similar to the effect obtained by m. xanthus myxospores. data showed that the immune response modifier properties of m. xanthus myxospores are principally present in the coats.19902128333
nucleotide sequence and transcriptional products of the csg locus of myxococcus xanthus.the csg locus of myxococcus xanthus appears to control the production of an intercellular signal that is essential for development. the complete nucleotide sequence of a clone containing the csg locus was determined by the dideoxy-chain termination method. pattern recognition analyses of the dna sequence revealed the presence of two protein-coding regions that are convergently oriented and separated by only 8 nucleotides. tn5 lac insertions into this clone detected two transcriptional units that ...19902152896
the myxococcus xanthus fpra protein causes increased flavin biosynthesis in escherichia coli.the fpra gene is immediately adjacent to the csga gene (formerly known as spoc) of myxococcus xanthus. whereas the csga gene has an essential role in cell interactions during the developmental cycle, the function of the fpra gene is unknown. gene disruption was used to determine what affect a null mutation in this gene has on the phenotype of the cell. a csga-fpra deletion and an fpra frameshift mutation were constructed in vitro in a cloned copy of this locus and then inserted into the m. xanth ...19902152902
defects in fruiting body development caused by tn5 lac insertions in myxococcus xanthus.mutations caused by insertions of tn5 lac that block development are rare. at least six of the eight mutations examined appeared to be regulatory. three of these were found to disrupt social motility, suggesting a particular importance for this function. one other occurred in a known cell-cell interaction gene, bsga, and the remaining two were located in genes operative early in the developmental program.19902152913
nucleoside diphosphate kinase from myxococcus xanthus. i. cloning and sequencing of the gene.by photoaffinity labeling with a photolysable analog of gtp, 8-n3gtp, we were able to find at least five distinct gtp-binding proteins in myxococcus xanthus; two of them located in the membrane and the other three in the soluble fraction. the amino-terminal sequence of the 16-kda gtp-binding protein from the soluble fraction was determined, and the gene that encodes this protein was isolated and cloned using degenerate oligonucleotides as a probe. the dna sequence of the gene was determined, whi ...19902154455
nucleoside diphosphate kinase from myxococcus xanthus. ii. biochemical characterization.the gene that encodes the 16-kda gtp-binding protein from myxococcus xanthus has been cloned, and its dna sequence has been determined. the gene has been expressed in escherichia coli by using the lacz promoter, and its gene product was overproduced (muñoz-dorado, j., inouye, m., and inouye, s. (1990) j. biol. chem. 265, 2702-2706). the gene product thus overproduced in e. coli was purified to homogeneity by a simple four-step procedure and crystallized. gel filtration of the purified protein re ...19902154456
alkaline, acid, and neutral phosphatase activities are induced during development in myxococcus xanthus.one of the signals that has been reported to be important in stimulating fruiting body formation of myxococcus xanthus is starvation for phosphate. we therefore chose to study phosphatase activity during m. xanthus development. many phosphatases can cleave the substrate p-nitrophenol phosphate. using this substrate in buffers at various phs, we obtained a profile of phosphatase activities during development and germination of m. xanthus. these experiments indicated that there are five patterns o ...19902158968
cloning, disruption, and transcriptional analysis of three rna polymerase sigma factor genes of streptomyces coelicolor a3(2).the rpod gene of myxococcus xanthus was used as a probe to isolate three streptomyces coelicolor genes, hrdb, hrdc, and hrdd, which appear to encode rna polymerase sigma factors extremely similar to the sigma 70 polypeptide of escherichia coli. gene disruption experiments suggested that hrdb is essential in s. coelicolor a3(2) but showed that hrdc and hrdd mutants are viable and are apparently unaffected in differentiation, gross morphology, and antibiotic production. s1 nuclease mapping showed ...19902160942
genetic analysis of tag mutants of myxococcus xanthus provides evidence for two developmental aggregation systems.temperature-dependent aggregation mutants (tag) of the myxobacterium myxococcus xanthus aggregated into mounds and developed into fruiting bodies normally at 28 degrees c; however, they failed to form mounds at 34 degrees c. the timing of sporulation was unaffected by the mutations, and normal numbers of spores were produced at both permissive and restrictive temperatures. this class of mutations was originally identified through screening of ethyl methanesulfonate (ems)-generated mutations. sub ...19902163391
genome size of myxococcus xanthus determined by pulsed-field gel electrophoresis.genomic dna of the myxobacterium myxococcus xanthus was digested with the rare cutting restriction endonuclease asei or spei, and the restriction products were separated by pulsed-field gel electrophoresis. transposons tn5-132 and tn5 lac, which contain asei restriction sites, were used to determine the number of restriction fragments in each band. the size of the genome was determined by adding the molecular sizes of the restriction products. the genomes of strains dk101, md2, and dzf1 have ide ...19902165472
role of autocide ami in development of myxococcus xanthus.a new developmental mutant of myxococcus xanthus has been isolated by screening tnv insertion mutants for ami-dependent development in submerged culture. this mutant (er304) aggregated and sporulated on agar surfaces but required at least 3.8 micrograms of autocide ami per ml for development in submerged cultures. spore rescue of er304 was obtained with the saturated, monounsaturated, and diunsaturated fatty acid fractions of ami, with specific activities of 68, 115, and 700 u/mg, respectively. ...19902165474
frze of myxococcus xanthus is homologous to both chea and chey of salmonella typhimurium.myxococcus xanthus exhibits multicellular development. the "frizzy" (frz) mutants are unable to complete the developmental pathway. instead of forming fruiting bodies, these mutants form tangled filaments of cells. we have previously shown that four of the frz gene products are homologous to enteric chemotaxis proteins and have proposed that the frz genes constitute a signal-transduction pathway that controls the frequency at which cells reverse their gliding direction. we show here that frze en ...19902165608
developmental sensory transduction in myxococcus xanthus involves methylation and demethylation of frzcd.myxococcus xanthus is a bacterium that moves by gliding motility and exhibits multicellular development (fruiting body formation). the frizzy (frz) mutants aggregate aberrantly and therefore fail to form fruiting bodies. individual frz cells cannot control the frequency at which they reverse direction while gliding. previously, frzcd was shown to exhibit significant sequence similarity to the enteric methyl-accepting chemotaxis proteins. in this report, we show that frzcd is modified by methylat ...19902168368
defects in contact-stimulated gliding during aggregation by myxococcus xanthus.during development, myxococcus xanthus cells glide toward foci of aggregation and produce compact multicellular mounds. we studied development in strains with defects in contact-stimulated gliding. contact stimulation involves a mechanism influenced by contacts between neighboring cells which stimulates the gliding motility of single cells (hodgkin and kaiser, proc. natl. acad. sci. usa 74:2938-2942, 1977; hodgkin and kaiser, mol. gen. genet. 171:167-176, 1979). most mutants containing a mutatio ...19902172215
transposon tagging of genes for cell-cell interactions in myxococcus xanthus.the prokaryote myxococcus xanthus is a model for cell interactions important in multicellular behavior. we used the transposon tnphoa to specifically identify genes for cell-surface factors involved in cell interactions. from a library of 10,700 insertions of tnphoa, we isolated 36 that produced alkaline phosphatase activity. three tnphoa insertions tagged cell motility genes, called cgl, which control the adventurous movement of cells. the products of the tagged cgl genes could function in tran ...19902172982
primary structure of a fucose-specific lectin obtained from a mushroom, aleuria aurantia.aleuria aurantia lectin (aal) is a protein composed of two identical subunits having no carbohydrate chain and shows sugar-binding specificity for l-fucose. full-length cdna encoding for the lectin has been isolated from a lambda gt11 library, screened with an antiserum directed against aal. the cdna clone contained 1,370 nucleotides and an open reading frame of 939 nucleotides encoding 313 amino acids. the amino-terminal sequence (residues 1-30) of the lectin isolated from the mushroom coincide ...19902193930
suppressors that permit a-signal-independent developmental gene expression in myxococcus xanthus.progression through the early stages of myxococcus xanthus fruiting body development requires the cell-to-cell transmission of soluble material called a signal. during these early stages, expression from the gene identified by tn5 lac insertion omega 4521 increases. a dna probe of the omega 4521 gene was constructed. use of this probe showed that accumulation of mrna corresponding to the omega 4521 gene depends upon a signal. a-signal-deficient (asg) mutants fail to accumulate this rna, and the ...19911704885
early events in the synthesis of the multicopy single-stranded dna-rna branched copolymer of myxococcus xanthus.myxobacteria and a variety of strains of escherichia coli contain an unusual extrachromosomal element, a small single-stranded branched copolymer of dna and rna (msdna). interest in msdna stems from the presence of a 2'-5' linkage between its dna and rna moieties and the possible involvement of reverse transcriptase in its synthesis. two groups have proposed a model for the synthesis of msdna that involves the following sequence of events: 1) synthesis of an rna precursor; 2) addition of a dntp ...19911713583
survey of multicopy single-stranded dnas and reverse transcriptase genes among natural isolates of myxococcus xanthus.twenty different isolates of the soil bacterium myxococcus xanthus were examined for the presence of multicopy single-stranded dna (msdna)-producing retroelements, or retrons. each strain was analyzed by ethidium bromide staining for msdna, 32p labeling of the msdna molecule by the reverse transcriptase (rt) extension method, and dna hybridization experiments with probes derived from two retrons, mx162 and mx65, previously cloned from m. xanthus dzf1. these analyses revealed that all m. xanthus ...19911715854
a development-specific protein in myxococcus xanthus is associated with the extracellular fibrils.we have been using monoclonal antibodies (mabs) as probes to study developmentally relevant cell surface antigens (csa) that may be required for cellular interactions in myxococcus xanthus. three independently isolated mabs, g69, g357, and g645, isolated by gill and dworkin recognize a csa detectable only on developing cells (j. s. gill and m. dworkin, j. bacteriol. 168:505-511, 1986). the csa is made within the first 30 min of submerged development and increases until myxosporulation. the csa i ...19911718941
msdna and bacterial reverse transcriptase. 19911720608
a transposition of the reverse transcriptase gene reveals unexpected structural homology to e. coli dna polymerase i.the rational design of antiviral agents targeting the reverse transcriptase (rt) of the human immunodeficiency virus (hiv) would greatly benefit from a more intimate knowledge of the structure of rt. until now, the degree of sequence similarity between rt and e. coli dna polymerase i (pol i) has been thought to be confined to several small regions, suggesting little basis for homology molecular modeling. however, we have found that a region in the c terminal of the rt polymerase domain is homolo ...19911721884
crystallization and preliminary x-ray diffraction analysis of oucleoside diphosphate kinase from myxococcus xanthus.nucleoside diphosphate (ndp) kinase catalyzes the transfer of the gamma-phosphate from a nucleoside triphosphate to a nucleoside diphosphate. human and rodent forms of this enzyme have been shown to be suppressors of metastasis. crystals that diffract x-rays to high resolution have been obtained for the recombinant myxococcus xanthus ndp kinase expressed in and purified from escherichia coli. two crystal forms have been obtained. both forms are orthorhombic, space group i222 (or i2(1)2(1)2(1)) w ...19911648623
nucleoside diphosphate kinase from escherichia coli; its overproduction and sequence comparison with eukaryotic enzymes.the gene encoding nucleoside diphosphate (ndp) kinase of escherichia coli was identified by polymerase chain reaction using oligodeoxyribonucleotide primers synthesized on the basis of consensus sequences from myxococcus xanthus and various eukaryotic ndp kinases. the gene (ndk), mapped at 54.2 min on the e. coli chromosome, was cloned and sequenced. the e. coli ndp kinase was found to consist of 143 amino acid residues that are 57, 45, 45, 42, 43, and 43% identical to the m. xanthus, dictyostel ...19911657712
intercellular signaling in myxococcus development: the role of c factor.cell communication governs differentiation and morphogenesis in fruiting body formation by myxococcus xanthus. transmission of a small short-range intercellular signal by a protein called c factor directs multicellular pattern formation and coordinates the timing of major developmental events.19911668187
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