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[Viability of lyophilized cells of Myxococcus xanthus UKM 10041 and Polyangium cellulosum UKM 10043 in presence of different antioxidants].

It has been established that addition of antioxidants: cystamine, ionol, alpha-tocopherol to protective media (saccharose-gelatin agar) does not affect considerably viability of lyophillized cells of cultures Myxococcus xanthus UCM 10041 and Polyangium cellulosum UCM 10043. Experimentally obtained and predicted data on the survival of cells of M. xanthus UCM 10041 and P. cellulosum UCM 10043 are the values of the same order which evidences for the possibility of the use of quick test for prediction of myxobacteria cells survivability under long-term storage.

Antioxidants↗
PubMed1992

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 these four regions and one region contains a tight cluster of 5 conserved residues, certain of which may be catalytically active residues. A second open reading frame was found upstream of uraA and oriented in the same direction as uraA. A stretch of 21 consecutive pyrimidine (C or T) residues were found in the intercistronic region between the potential ribosome-binding site of uraA and the UGA stop codon of the upstream open reading frame. RNA directly upstream of the pyrimidine run, including the UGA stop codon of the upstream open reading frame, could be folded into a stable hairpin structure resembling Rho-independent terminators of Escherichia coli. Expression of the uraA gene may be regulated by an intercistronic transcription termination mechanism.

Amino Acid Sequence↗
PubMed1994

Autolytic effect of the antibiotic produced by Myxococcus coralloides D.

Myxococcus coralloides D secretes an antibiotic, named corallolysin, when grown on a rich medium. When a critical concentration is reached, this antibiotic lyses the producer bacterium either during vegetative growth or during morphogenesis. Corallolysin has not effect on resting cells nor on myxospores. The autolytic effect is caused by the early inhibition of RNA synthesis.

Anti-Bacterial Agents↗
PubMed1994

Elastolytic activity of MAP1, a protease from Myxococcus xanthus.

MAP1, a protease isolated from Myxococcus xanthus, is demonstrated to be an elastase. Although its elastolytic activity is lower than that of other well-known elastases, the size distribution of solubilized elastin peptides is similar. MAP1 as pancreatic elastase releases peptides with molecular weights higher than 10,000. However, the specificity of MAP1 is different since this enzyme cannot hydrolyze alanine oligomers as do pancreatic and Pseudomonas aeruginosa elastases.

Animals↗
PubMed1994

Increases in the intracellular concentration of glycerol during development in Myxococcus xanthus.

The role of glycerol as a natural morphogen of myxospore formation in Myxococcus xanthus was examined. Glycerol was extracted from cells undergoing development and analyzed by gas chromatography. Glycerol is present in cells, and the intracellular level undergoes a series of transient increases during development. The data suggest a role for glycerol in myxosporulation and fruiting body morphogenesis, supporting the notion that this chemical induction of sporulation may represent a physiological pathway in development.

Chromatography, Gas↗
PubMed1995

Monoclonal antibodies against antigens exposed on the surface of vegetative forms and spores of Myxococcus virescens.

Twelve monoclonal antibodies (mAbs) directed against cell-surface antigens of Myxococcus virescens cells were developed and partially characterized. All of them recognized multiple, diffuse proteic bands in Western blot and four were also reactive to living bacteria, as assessed by flow cytometry. The four latter mAbs recognized antigens common to a number of vegetative forms and spores. The selective expression of proteins recognized by mAbs on the microorganisms and the possible applications of mAbs to the study of myxobacterial cell interaction are discussed.

Antibodies, Bacterial↗
PubMed1999

The first gene in the biosynthesis of the polyketide antibiotic TA of Myxococcus xanthus codes for a unique PKS module coupled to a peptide synthetase.

The polyketide antibiotic TA is synthesized by the Gram negative bacterium Myxococcus xanthus in a multi-step process in which a unique glycine-derived molecule is used as a starter unit and elongated through the condensation of 11 acetate molecules by polyketide synthases (PKSs). Analysis of a 7.2 kb DNA fragment, encoding the protein that carries out the first condensation step, revealed that the fragment constitutes a single open reading frame, referred to as Ta1, which lacks the 5' and 3' ends and displays two regions of similarity to other proteins. The first 1020 amino acid residues at the N terminus of the polypeptide are similar to sequences of the large family of enzymes encoding peptide synthetases. They are followed by a second region displaying a high degree of similarity to type I PKS genes. The genetic analysis of this open reading frame is compatible with the proposed chemical structure of TA. The data indicate that the genes encoding TA have a modular gene organization, typical of a type I PKS system. The unusual feature of Ta1 is that the first PKS module of TA resides on the same polypeptide as the peptide synthetase functional unit.

Acetates↗
PubMed1990

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.

Anti-Bacterial Agents↗
PubMed1990

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 causes constitutive expression of the light-inducible gene carB, which is linked to carA. In the dark, the carA mutant produces high levels of phytoene, the first C40 colourless carotenoid precursor; in the light, it produces the same carotenoids as the wild type. Since a mutation in carB blocks accumulation of phytoene, we propose that carB, and probably other linked genes also controlled by carA, code for enzymes involved in the synthesis of phytoene. This is virtually the only carotene accumulated by strains mutated in the gene carC, which is unlinked to the others. Thus carC codes for phytoene dehydrogenase, the enzyme that converts phytoene into coloured carotenoids. The results presented here also provide evidence for control of carotenogenesis by an endproduct that is independent of the blue light effect.

Carotenoids↗
PubMed1981

Misrepair mutagenesis in Myxococcus xanthus: induction of rifampicin-resistant mutants by N-methyl-N'-nitro-N-nitrosoguanidine and ultraviolet-irradiation.

In the ultraviolet (UV)-mutable bacterium, Myxococcus xanthus, dose response curves for the induction of rifampicin-resistant (Rifr) mutants were compared with dose response curves for Weigle(W)-reactivation of the UV-irradiated phage Mx4 at a phage survival of 5 X 10(-6). In most strains examined, including a uvr mutant, these curves are largely similar. Unexpectedly the UV-sensitive strain M. xanthus Bt, which is unable to perform W-reactivation, is nevertheless UV-mutable. This result may indicate that the repair pathway involved in phage reactivation is only partly responsible for UV-mutagenesis or alternatively is not able to act on phage DNA in M. xanthus Bt cells. N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) treatment of M. xanthus cells also results in marked W-reactivation of the UV-irradiated phage Mx4 at the same survival of 5 X 10(-6). The MNNG-stimulated phage reactivation is of the same order of magnitude as the UV-stimulated phage reactivation. Also the dose response curves for the induction of Rifr mutants by MNNG and the MNNG-stimulated phage reactivation are quite similar. This coincidence may indicate that misrepair mutagenesis is involved in both UV and MNNG-mutagenesis. It is suggested that M. xanthus is a useful organism with which to study misrepair mutagenesis in bacteria.

Bacteriophages↗
PubMed1985

Physical characterization of the genome of the Myxococcus xanthus bacteriophage MX-8.

We have constructed a restriction map for the genome of bacteriophage MX-8 from Myxococcus xanthus using the enzymes PvuII, MboI, and EcoRI. The phage genome size, as determined by restriction analysis, is 51.7 +/- 0.6 Kb. Double digestions, redigestions of isolated fragments, and crossed-contact hybridization of partial digestion products show that the restriction map is circular. Restriction analysis and Southern hybridization show that the phage DNA molecules are packaged sequentially from a concatemer starting from a specific site which we have mapped. The DNA molecules have an average terminal redundancy of approximately 8% and are circularly permuted over at least 40% of the genome.

Bacteriophages↗
PubMed1985

Functional complementation between the two homologous genes, ops and tps, during differentiation of Myxococcus xanthus.

Protein S is a development-specific protein of Myxococcus xanthus encoded by the tps gene. It has been shown that there are two extensively homologous genes (ops and tps) tandemly repeated in the same direction with a 1.4 kb spacer fragment between them (Inouye et al. 1983). Seven deletion mutants were constructed by removing the ops gene, the tps gene, segments of the spacer sequence or combinations of these regions. The deleted regions were replaced with DNA fragments carrying the Tn5 gene for kanamycin resistance. The effects of deleting different regions on morphological changes and on patterns of protein synthesis during fruiting body formation were examined. The process of fruiting body formation was severely delayed when both the ops and the tps genes were deleted. However, this delay could be suppressed by either the ops gene or the tps gene, individually, although in the latter case, a slight delay was still observed. These results indicate that the ops gene is expressed during fruiting body formation and plays a role in the normal program of M. xanthus differentiation. Furthermore, the role of the ops gene can be complemented by the tps gene. The deletion of the ops and/or tps genes had no effect on glycerol-spore formation.

Bacterial Proteins↗
PubMed1989

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 mutant (asgB480) alleles in Escherichia coli plasmid. Tandem duplications of the asgB locus were constructed in M. xanthus; the completely wild-type phenotype of asgB+/asgB480 partial diploids implies that the asgB480 allele is recessive. This finding, along with extracellular complementation by wild-type cells, is consistent with the hypothesis that the asgB+ locus is required to produce a substance with an intercellular signalling function. At least part of the asgB gene was found to lie within a 1.2 kb SmaI DNA fragment. This 1.2 kb fragment, as well as smaller fragments derived from it, were used as DNA probes in RNA/DNA hybrid analyses of transcription in the asgB region. Two small mRNA species were detected, one about 650 bp long, and the other about 500 bp; the two species of mRNAs apparently overlap. Both mRNAs are present in low, but approximately equal amounts, in vegetatively growing cells. This is consistent with the observation that asg mutants display a mutant vegetative phenotype (a change in colony color and spreading behavior) as well as defective development.

Blotting, Northern↗
PubMed1988

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 recombinant DNA molecule containing all or part of the locus to Csg mutants and examining the sporulation and rippling phenotypes of the transductants. Three methods were used to integrate the csg locus into the chromosome. First, the entire molecule was integrated into the chromosome by a single homologous crossover. Second, a portion of the molecule was integrated into the chromosome by two flanking homologous crossovers. Third, the entire molecule was integrated into the chromosome by site-specific recombination at a bacteriophage attachment site. Together, these techniques suggested that all of the functions of the csg locus are carried on a DNA fragment of 1.9 kbp or less. The locus appears to contain two smaller units of function. Transposon insertions or deletions in the right end of the locus disrupted sporulation and intercellular complementation of Csg mutants for sporulation, but did not disrupt rippling. The intercellular complementation of Csg mutants may reflect a natural and necessary step in the sporulation of wild-type cells, since the ability to sporulate and the ability to stimulate Csg mutants to sporulate were inseparable by any of these methods.

DNA Transposable Elements↗
PubMed1985

Cloning and complementation analysis of the "Frizzy" genes of Myxococcus xanthus.

Fruiting-body formation in Myxococcus xanthus involves the aggregation of cells into raised mounds, where they sporulate. "Frizzy" mutants fail to aggregate into mounds, but rather aggregate into "frizzy" filaments (D.R. Zusman 1982). The frizzy mutations (frz) were found to be genetically linked. The region of DNA carrying the frz genes was cloned in Escherichia coli by selecting for the kanamycin resistance element present on a transposon Tn5 insertion linked to the frz genes. Phage P1 mediated transduction of the cloned DNA into M. xanthus frizzy mutants showed that the cloned DNA could complement the frz mutations. The cloned DNA was analyzed by isolating and characterizing new Tn5 insertions at short intervals within the M. xanthus DNA and by constructing in vitro deletions. The mutated DNA was then transduced into M. xanthus where the cloned DNA became integrated into the bacterial chromosome as gene replacements or as merodiploids. The gene replacement strains allowed us to define the limits of the frz region, since Tn5 insertions in the frz genes resulted in the frizzy phenotype. The merodiploid strains allowed us to perform complementation analyses. Using appropriate crosses, we were able to identify 5-6 frz complementation groups on 7.5 kb of cloned DNA. One of the complementation groups was separated from the others by 1.4 kb of DNA, whereas the others were contiguous. The different frz loci behave as separate transcriptional groups although interactions between some of the gene products are indicated.

Bacteria↗
PubMed1978

Purification and effects of fulvocin C, a bacteriocin from Myxococcus fulvus Mx f16.

Fulvocin C is a bacteriocin from Myxococcus fulvus Mx f16. It has a molecular weight of 4672 and is one of the smallest bacteriocins known. Four disulfide bonds give the molecule a tight structure, so that its native form was not attacked by chymotrypsin or pronase. Fulvocin C was stable in various organic solvents and could tolerate 80 degrees C in aqueous solution without loss of activity. The killing effect of fulvocin C was observed only at concentrations higher than 0.25 mumol/1. Macromolecular synthesis (DNA, RNA, protein) was affected very gradually. Viability in growing cultures decreased slowly from 100 to 25% during one generation (8 h). Cell division was affected early. After one generation v-shaped cell pairs had accumulated in the culture. Electron microscopic pictures revealed extended membrane systems connected with the inner membrane. The most striking effect was that often the outer membranes of neighbouring cells seemed to have fused laterally. With further incubation many cells lost their rod shape and empty bags became predominant.

Bacterial Proteins↗
PubMed1981

beta-Lactamase activity and resistance to penicillins in Myxococcus xanthus.

Several mutants and other variants of Myxococcus xanthus HP100 were obtained with differences in their sensitivity to carbenicillin and other penicillin derivatives. The specific activities of beta-lactamase in different resistant organisms varied from strain to strain but were consistently higher than in HP100. The relative molecular mass (Mr) of the enzyme in M. xanthus HP100 was found to be 22,300. In certain carbenicillin resistant strains a second fraction of beta-lactamase activity of molecular weight 186,000 presumed to be an octamer of the other form was present. The enzyme was found in cell free extracts and also in culture supernatants of all carbenicillin resistant mutants but not in culture supernatants of strain HP100. In all the carbenicillin resistant mutants a part of the intracellular enzyme activity was released by osmotic shock and this activity may be periplasmic. The forms of the enzyme present in the culture supernatants and released by osmotic shock were monomeric. Carbenicillin resistance was not transferable between strains by conjugation. One resistance allele inhibited the transfer of the R factor Sa between myxococci.

Carbenicillin↗
PubMed1981

Plasmid-mediated UV-protection in Myxococcus xanthus.

Plasmid R46 was successfully transferred from Escherichia coli K=12 into myxococcus xanthus strain MD-1 but not into M. xanthus strain XK. Plasmid R68.45 was transferred from E. coli K-12 into both strains of M. xanthus. The effects of these plasmids on survival of M. xanthus after ultraviolet (UV)-244 nm irradiation, the ability of M. xanthus to reactivate irradiated myxophages, and weigle reactivation of UV-irradiated effect on UV survival of M. xanthus, but increased the host's ability to reactivation irradiated myxophages. Plasmid R68.45 protected M. xanthus strains MD-1 and XK against the lethal effects of UV irradiation and also increased the host's ability to reactivate irradiated myxophages.

Bacteriophages↗