| 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 ... | 1990 | 1693144 |
| the isolation and characterization of gliding motility mutants of myxococcus xanthus. | nonmotile and motility-altered mutants of myxococcus xanthus have been obtained by the use of chemical mutagens, ultraviolet irradiation, and a procedure for selective spontaneous mutants. as judged by their behaviour on a variety of growth media, in both plate and slide culture, the mutants were divided into four groups. one group contains mutants which are truly nonmotile. myxococcus xanthus nm, previously described as a nonmotile mutant, may be similar to type 3 mutants (described in text). | 1976 | 824040 |
| [myxobacteria of the myxococcus family as indirect indicators of fecal matter in surface water. 1. communication (author's transl)]. | the fruiting-body-forming myxobacteria of the myxococcus order are coprophilic, i.e., they accumulate in biotopes that contain faecal substances. therefore, a special detection of myxococcus in water, based on the membrane-filter method, has been worked-out. field studies, undertaken in the region of a mechanico-biological clarifying plant, above a certain stretch of a stream (the regnitz) laden with waste-water, and on the bodensee (=lake constance) have revealed a clear correlation between the ... | 1975 | 808923 |
| the function of fimbriae in myxococcus xanthus. ii. the role of fimbriae in cell-cell interactions. | anti-fimbriae antiserum specifically inhibited swarming but no gliding motility per se in myxococcus xanthus. however, formation of motile aggregates on agar and clumps in liquid media correlated with the presence of fimbriae. ethylenediaminetetraacetic acid which inhibited swarming also inhibited fimbriae formation. direct electron-microscopic observations revealed that fimbriae establish contact with apposing cell surfaces. intact but not depolymerized fimbriae exhibited hemagglutination activ ... | 1979 | 43768 |
| aspartokinase isoenzymes of the fruiting myxobacterium myxoccus xanthus. | two isoenzymes of aspartokinase can be found in extracts of the differentiating bacterium myxococcus xanthus. aspartokinase i is repressed by l-lysine and feedback is inhibited by meso-diaminopimelate and by low concentrations of l-lysine. however, the inhibition by l-lysine is no longer observed at high concentration of this amino acid. aspartokinase ii is repressed and feedback inhibited specifically by l-threonine. both enzymes are stimulated significantly by l-methionine and l-isoleucine; th ... | 1975 | 170969 |
| 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 ... | 1991 | 1704885 |
| 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 ... | 1991 | 1713583 |
| 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 ... | 1991 | 1715854 |
| 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 ... | 1991 | 1718941 |
| msdna and bacterial reverse transcriptase. | | 1991 | 1720608 |
| 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 ... | 1991 | 1721884 |
| the orotidine-5'-monophosphate decarboxylase gene of myxococcus xanthus. comparison to the omp decarboxylase gene family. | the nucleotide sequence of the myxococcus xanthus orotidine-5'-monophosphate decarboxylase (omp dcase) gene was determined. the derived protein sequence is not closely related to other prokaryotic omp dcase sequences; nor is it closely related to any eukaryotic omp dcase sequences. progressive multiple alignment of the m. xanthus omp dcase protein sequence with 19 other omp dcase sequences revealed four conserved regions present in all 20 sequences. ten entirely conserved residues were found in ... | 1992 | 1730672 |
| extracellular fibrils and contact-mediated cell interactions in myxococcus xanthus. | contact-mediated cell-cell interactions play an important role in the social life-style of myxococcus xanthus. previous investigations have demonstrated that fimbriae (also referred to as pili) and extracellular fibrils are involved in these social interactions (l. j. shimkets, microbiol. rev. 54:473-501, 1990). we have used the relatively new technique of low-voltage scanning electron microscopy (an ultra-high-resolution scanning technique that allows for the nanometer resolution of biological ... | 1991 | 1744036 |
| release of a cell surface protein during development of myxococcus xanthus. | vgp is a major cell-surface glycoprotein present in vegetative cells of myxococcus xanthus. serological assays indicated that this protein was released from cells and accumulated in the medium during development, i.e., aggregation, fruiting body formation, and myxosporulation. cells induced to form spores in the absence of aggregation retained vgp, indicating that loss of vgp was associated with developmental aggregation rather than myxosporulation. anti-vgp antibodies inhibited vegetative cell ... | 1991 | 1744056 |
| sensory transduction in the gliding bacterium myxococcus xanthus. | sensory transduction in the gliding bacterium myxococcus xanthus is mediated by the frz genes. these genes are homologous to the chemotaxis genes of enteric bacteria and control the rate of cell reversal during gliding. sensory transduction is hypothesized to involve the recognition of substances present in the medium at the cell surface and the subsequent stimulation of a cytoplasmic methyl-accepting protein, frzcd. phosphorylation of frze is also involved in the sensory transduction pathway. d ... | 1991 | 1791749 |
| a gene encoding a protein serine/threonine kinase is required for normal development of m. xanthus, a gram-negative bacterium. | pcr reactions were carried out on the genomic dna of m. xanthus, a soil bacterium capable of differentiation to form fruiting bodies, using oligonucleotides representing highly conserved regions of eukaryotic protein serine/threonine kinases. a gene (pkn1) thus cloned contains an orf of 693 amino acid residues whose amino-terminal domain shows significant sequence similarity with the catalytic domain of eukaryotic protein serine/threonine kinases. the pkn1 gene was overexpressed in e. coli, and ... | 1991 | 1835671 |
| sequence of hrdb, an essential gene encoding sigma-like transcription factor of streptomyces coelicolor a3(2): homology to principal sigma factors. | the complete nucleotide sequence of the hrdb gene, an essential gene of streptomyces coelicolor a3(2), indicates the presence of an open reading frame encoding a putative polypeptide of 442 amino acid (aa) residues with an mr of 48,412. the principal sigma-like transcriptional factor of s. coelicolor (hrdb) protein showed an extensive aa sequence homology with the known principal sigma factors of escherichia coli, bacillus subtilis, pseudomonas aeruginosa and myxococcus xanthus. the degree of se ... | 1991 | 1840545 |
| cell-cell interactions that direct fruiting body development in myxococcus xanthus. | the soil bacterium, myxococcus xanthus initiates a developmental program when nutrients are limited. this results in the formation of a multicellular fruiting body structure filled with differentiated, environmentally resistant spores. at least four cell-cell signals, cell motility, and aggregation functions are required for the completion of fruiting body formation. | 1991 | 1840894 |
| c-factor has distinct aggregation and sporulation thresholds during myxococcus development. | c-factor, the protein product of the csga gene, acts as a short-range morphogenetic signal. it is required for fruiting body development of the gram-negative bacterium myxococcus xanthus. aggregation, sporulation, and expression of a set of genes that are c-factor dependent, all of which fail in csga mutant cells, are completely restored by addition of purified c-factor. we report here that, depending on its concentration, c-factor can elicit two distinct morphogenetic and transcriptional respon ... | 1991 | 1847908 |
| physical map of the myxococcus xanthus chromosome. | the genome of myxococcus xanthus, which is 9,454 kbp, is one of the largest bacterial genomes. the organization of the dna and the distribution of genes encoding social and developmental behaviors were examined by using pulsed field gel electrophoresis. intact genomic dna was digested with asei into 16 restriction fragments, which were separated by contour-clamped homogeneous electric field electrophoresis, purified, and radiolabeled. each asei fragment was hybridized to spei-digested dna and to ... | 1991 | 1848221 |
| transcription of the myxobacterial hemagglutinin gene is mediated by a sigma 54-like promoter and a cis-acting upstream regulatory region of dna. | myxobacterial hemagglutinin (mbha) is a major developmentally induced protein that accumulates during the period of cellular aggregation of the fruiting bacterium myxococcus xanthus. in this study, dna sequences mediating the transcriptional regulation of mbha have been identified. examination of nucleotide sequences upstream of the start site for mbha transcription has indicated a region of dna that bears strong homology to the consensus sequence for promoters recognized by the sigma 54 holoenz ... | 1991 | 1850403 |
| a unique repetitive dna sequence in the myxococcus xanthus genome. | we found a novel type of repetitive dna sequence in the myxococcus xanthus genome. the first repetitive sequence is located in the spacer region between the ops and tps genes. we cloned five other repetitive sequences using the first repetitive sequence as a probe and determined their nucleotide sequences. comparison of these sequences revealed that the repetitive sequences consist of a 87-bp core sequence and that some clones share additional homology on their flanking regions. | 1991 | 1900509 |
| myxococcus xanthus protein c is a major spore surface protein. | fruiting body formation in myxococcus xanthus involves the aggregation of cells to form mounds and the differentiation of rod-shaped cells into spherical myxospores. the surface of the myxospore is composed of several sodium dodecyl sulfate (sds)-soluble proteins, the best characterized of which is protein s (mr, 19,000). we have identified a new major spore surface protein called protein c (mr, 30,000). protein c is not present in extracts of vegetative cells but appears in extracts of developi ... | 1991 | 1900510 |
| low-temperature induction of myxococcus xanthus developmental gene expression in wild-type and csga suppressor cells. | the csga gene encodes an extracellular protein that plays an essential role in the regulation of fruiting-body formation and sporulation of myxococcus xanthus. the csga suppressor allele soc-500 (formerly referred to as csp-500) was selected based on its ability to restore sporulation to csga cells under developmental conditions at 32 degrees c. the soc-500 allele was subsequently found to induce sporulation of csga+ or csga cells simply by shifting the temperature of vegetatively growing cells ... | 1991 | 1901052 |
| development in myxococcus xanthus involves differentiation into two cell types, peripheral rods and spores. | myxococcus xanthus, a gram-negative bacterium, has a complex life cycle. in response to starvation, most cells in a population participate in the formation of multicellular aggregates (i.e., fruiting bodies) in which cells differentiate into spores. however, some cells do not enter aggregates. in this and the two accompanying reports, the biology and physiology of these nonaggregated cells is examined. a technique to separate aggregated cells from nonaggregated cells was developed; then differen ... | 1991 | 1904430 |
| analysis of myxococcus xanthus cell types by two-dimensional polyacrylamide gel electrophoresis. | myxococcus xanthus is a gram-negative, soil-dwelling bacterium that undergoes development in response to depletion of nutrients. whereas most cells aggregate into multicellular mounds in which they differentiate into spores, 10 to 20% of the developing cells remain outside fruiting bodies as peripheral rods. we used two-dimensional polyacrylamide gel electrophoresis to analyze the global expression of polypeptides in cells taken from six stages in the life cycle: vegetatively growing cells, cell ... | 1991 | 1904431 |
| behavior of peripheral rods and their role in the life cycle of myxococcus xanthus. | myxococcus xanthus is a gram-negative bacterium with a complex life cycle including a developmental phase in which cells aggregate and sporulate in response to starvation. in previous papers, we have described a heretofore unsuspected layer of complexity in the development of m. xanthus: vegetatively growing cells differentiate into two cell types during development. in addition to the differentiation of spores within fruiting bodies, a second cell type, peripheral rods, arises outside fruiting ... | 1991 | 1904432 |
| protein u, a late-developmental spore coat protein of myxococcus xanthus, is a secretory protein. | protein u is a spore coat protein produced at the late stage of development of myxococcus xanthus. this protein was isolated from developmental cells, and its amino-terminal sequence was determined. on the basis of this sequence, the gene for protein u (pru) was cloned and its dna sequence was determined, revealing an open reading frame of 179 codons. the product from this open reading frame has a typical signal peptide of 25 amino acid residues at the amino terminal end, followed by protein u o ... | 1991 | 1904442 |
| deoxyribonuclease activities in myxococcus coralloides d. | myxococcus coralloides d produced cell-bound deoxyribonucleases (dnases) during the exponential phase of growth in liquid medium. dnase activity was much higher than that detected in other myxobacterial strains and was fractionated into three different peaks by filtration through sephadex g-200. the dnases were named g, m and p. the optimum temperatures were 37 degrees c, 33 degrees c and 25 degrees c respectively, although high activities were recorded over the temperature range 20-45 degrees c ... | 1991 | 1917725 |
| targeted disruption of the myxococcus xanthus orotidine 5'-monophosphate decarboxylase gene: effects on growth and fruiting-body development. | the myxococcus xanthus gene coding for orotidine 5'-monophosphate (omp) decarboxylase (ec 4.1.1.23) was cloned. the m. xanthus uraa gene efficiently complemented an escherichia coli omp decarboxylase mutant, permitting it to grow in the absence of uracil. electroporation of m. xanthus with a circular plasmid carrying a selectable uraa::kan gene disruption resulted in homologous recombination at the chromosomal uraa locus. chromosomal integration of the gene disruption plasmid created heterozygou ... | 1991 | 1938885 |
| effects of glucosamine on lysis, glycerol formation, and sporulation in myxococcus xanthus. | glucosamine (glcn), which has previously been shown to rescue fruiting body formation, lysis, and sporulation in a developmental mutant (g. janssen and m. dworkin, dev. biol. 112:194-202, 1985), induced lysis in vegetative and developing wild-type cells and inhibited fruiting body formation. it also resulted in a transient, intracellular increase in the concentration of glycerol, a known sporulation inducer, and sporulation of the surviving cells. phospholipase activity, which was shown to be no ... | 1991 | 1938915 |
| bacillus subtilis chen, a homolog of chea, the central regulator of chemotaxis in escherichia coli. | the bacillus subtilis chen gene was isolated, sequenced, and expressed. it encodes a large negatively charged protein with a molecular weight of approximately 74,000. the predicted protein sequence has 33 to 34% identity with the escherichia coli and salmonella typhimurium chea and myxococcus xanthus frze sequences. these proteins are found to autophosphorylate and are members of the same histidine kinase signal modulating family. chen has several conserved regions (including the histidine that ... | 1991 | 1938941 |
| function of mgla, a 22-kilodalton protein essential for gliding in myxococcus xanthus. | single mutations in the mgla gene in myxococcus xanthus render cells incapable of gliding. the mgla strains are unique in that all other nonmotile strains of m. xanthus isolated are the result of at least two independent mutations in separate motility system genes. translational fusions of trpe, or of lacz, to mgla were constructed, and the resulting fusion polypeptides were used to generate antibodies. antibodies specific to mgla protein were purified. antibody-tagged mgla was found localized t ... | 1991 | 1938957 |
| upstream gene of the mgl operon controls the level of mgla protein in myxococcus xanthus. | the mgl operon contains two open reading frames (orfs) which are transcribed together. a collection of nonmotile mutants helped to define the downstream orf as the mgla gene. single mutations at the mgla locus completely abolish motility. a series of deletion mutations was constructed to determine the role of the upstream orf (now called mglb). a strain carrying a deletion in mglb and with an intact mgla produces small colonies. the cells are motile, but their rate of swarm spreading is reduced. ... | 1991 | 1938958 |
| 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 ... | 1990 | 2104614 |
| 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 ... | 1990 | 2107329 |
| 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 ... | 1990 | 2107980 |
| 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 ... | 1990 | 2111012 |
| 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 ... | 1990 | 2116988 |
| 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 ... | 1990 | 2118274 |
| 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 ... | 1990 | 2118510 |
| 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 ... | 1990 | 2119047 |
| 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 ... | 1990 | 2120716 |
| 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 ... | 1990 | 2121605 |
| 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 ... | 1990 | 2123519 |
| 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 ... | 1990 | 2123853 |
| 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 ... | 1990 | 2125831 |
| 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 ... | 1990 | 2126150 |
| 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. | 1990 | 2128333 |
| 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 ... | 1990 | 2152896 |
| 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 ... | 1990 | 2152902 |
| 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. | 1990 | 2152913 |
| 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 ... | 1990 | 2154455 |
| 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 ... | 1990 | 2154456 |
| 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 ... | 1990 | 2158968 |
| 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 ... | 1990 | 2160942 |
| 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 ... | 1990 | 2163391 |
| 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 ... | 1990 | 2165472 |
| 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. ... | 1990 | 2165474 |
| 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 ... | 1990 | 2165608 |
| 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 ... | 1990 | 2168368 |
| 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 ... | 1990 | 2172215 |
| 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 ... | 1990 | 2172982 |
| 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 ... | 1990 | 2193930 |
| the mechanism of action of myxovalargin a, a peptide antibiotic from myxococcus fulvus. | myxovalargin a has two modes of action. at low concentrations (below 1 microgram/ml) it inhibits bacterial protein synthesis specifically and instantaneously. in vitro experiments suggest that it interferes with the binding of aminoacyl trna to the a site of the ribosome. at higher concentrations (above 5 micrograms/ml), or upon prolonged incubation, the antibiotic damages cell membranes. this leads to secondary effects, like decreased o2 consumption or instant break down of rna synthesis, and m ... | 1985 | 2415501 |
| 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 ... | 1987 | 2435705 |
| 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 ... | 1987 | 2446773 |
| 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 ... | 1988 | 2454233 |
| 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. | 1988 | 2459096 |
| 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 ... | 1988 | 2461359 |
| 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 ... | 1989 | 2464581 |
| 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 ... | 1989 | 2465091 |
| 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 ... | 1989 | 2465092 |
| 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 ... | 1989 | 2467910 |
| 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 ... | 1989 | 2475480 |
| "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 ... | 1989 | 2492105 |
| 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 ... | 1989 | 2493446 |
| 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. | 1989 | 2495265 |
| 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 ... | 1989 | 2495269 |
| 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 ... | 1989 | 2495270 |
| 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 ... | 1989 | 2501837 |
| 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 ... | 1989 | 2502539 |
| 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 ... | 1989 | 2503505 |
| 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 ... | 1989 | 2504693 |
| 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 ... | 1989 | 2504696 |
| 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 ... | 1989 | 2509312 |
| 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 ... | 1989 | 2509425 |
| 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. | 1989 | 2509428 |
| 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 ... | 1989 | 2509436 |
| 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 ... | 1989 | 2510171 |
| 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 ... | 1989 | 2539357 |
| 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 ... | 1989 | 2540147 |
| 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 ... | 1989 | 2540156 |
| 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 ... | 1989 | 2542221 |
| 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 ... | 1989 | 2544552 |
| 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 ... | 1989 | 2544553 |
| 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 ... | 1989 | 2553673 |
| 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 ... | 1989 | 2555667 |
| the corallopyronins, new inhibitors of bacterial rna synthesis from myxobacteria. | from the culture broth of the myxobacterium, corallococcus (myxococcus) coralloides, three new antibiotics have been isolated: corallopyronin a, b and c. the compounds, which are chemically related to the recently discovered myxopyronins, act mainly on gram-positive bacteria, with mic values between 0.1 and 10 micrograms/ml, and only exceptionally or at much higher concentrations (mic values; 100 and more micrograms/ml) on gram-negatives. they do not inhibit eukaryotic organisms and show no toxi ... | 1985 | 2581926 |
| 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 ... | 1989 | 2613931 |