Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| antifungal activity of myxococcus species 1 production, physicochemical and biological properties of antibiotics from myxococcus fulvus s110 (myxobacterales). | chloroform extracts of the culture supernatant of a strain of myxococcus fulvus isolated from soil were fungistatic and prevented germination of spores of botrytis cinerea. the antibiotics were produced during the exponential phase of growth and the effects of altering medium composition are described. the activity was fractionated into neutral, acidic and basic fractions. the neutral fraction had a molecular weight of 244 and was tentatively identified as 11-phenyl-undecadiene-2-ol. the acidic ... | 1993 | 8469176 |
| the two motility systems of myxococcus xanthus show different selective advantages on various surfaces. | myxococcus xanthus, a bacterium that forms fruiting bodies, moves by gliding motility utilizing dual motility systems that differ both genetically and morphologically [system a, having at least 21 genetic loci and moving mainly single cells, and system s, having at least 10 genetic loci and moving groups (rafts) of cells] [hodgkin, j. & kaiser, d. (1979) mol. gen. genet. 172, 177-191]. in this study, we found that a- and s-gliding-motility systems have different selective advantages on surfaces ... | 1993 | 8475084 |
| two cell-density domains within the myxococcus xanthus fruiting body. | myxococcus xanthus, one of the simplest of multicellular organisms, develops into an organized, multicellular aggregate, called a fruiting body. examination of the internal structure of the nascent fruiting body showed it to consist of a hemispherical outer domain of densely packed and ordered cells. inside this dense shell is an inner domain of less ordered cells at 3-fold lower cell density. single cells move in a bidirectional stream in the outer domain, orbiting the fruiting body throughout ... | 1993 | 8475116 |
| how and why bacteria talk to each other. | 1993 | 8500179 | |
| a new putative sigma factor of myxococcus xanthus. | a third putative sigma factor gene, sigc, has been isolated from myxococcus xanthus by using the siga gene (formerly rpod of m. xanthus) as a probe. the nucleotide sequence of sigc has been determined, and an open reading frame of 295 residues (m(r) = 33,430) has been identified. the deduced amino acid sequence of sigc exhibits the features which are characteristic of other bacterial sigma factors. the characterization of a sigc-lacz strain has demonstrated that sigc expression is induced immedi ... | 1993 | 8501037 |
| regulation of cohesion-dependent cell interactions in myxococcus xanthus. | myxococcus xanthus has two nearly independent genetic systems, a and s, which appear to mediate adventurous (single-cell) movement and social (group) movement, respectively. in addition to a notable reduction in group movement, social motility mutants exhibit decreased biofilm formation, cell cohesion, dye binding, fibril production, and fruiting body formation. the stk-1907 allele, containing transposon tn5 insertion omega dk1907, was introduced into wild-type cells and many social motility mut ... | 1993 | 8501067 |
| effect of dsp mutations on the cell-to-cell transmission of csga in myxococcus xanthus. | the dsp locus contains genes involved in the subunit synthesis and/or assembly of fibrils that radiate outward from the myxococcus xanthus cell surface and attach to other cells. the csga gene encodes an extracellular protein morphogen which is essential for fruiting body development. the question of whether fibrils are involved in the transmission of csga to adjacent cells was investigated in three ways. first, the dsp and csga mutants were mixed in a ratio of 1:1 and allowed to develop; fruiti ... | 1993 | 8501068 |
| rhizopodin, a new compound from myxococcus stipitatus (myxobacteria) causes formation of rhizopodia-like structures in animal cell cultures. production, isolation, physico-chemical and biological properties. | a new cytostatic compound, rhizopodin, was isolated from the culture broth of the myxobacterium, myxococcus stipitatus. the compound inhibited growth of various animal cell cultures without killing the cells. the id50, measured by an mtt assay, was 12 approximately 30 ng/ml, depending on the cell line. especially cells growing fibroblast-like showed typical morphological changes. they became larger and within hour formed long branching and reticular runners. these morphological changes were irre ... | 1993 | 8514628 |
| mlpa, a lipoprotein required for normal development of myxococcus xanthus. | the mlpa gene encoding a 236-residue polypeptide has been identified immediately downstream of the oar gene of myxococcus xanthus (m. martinez-canamero, j. munoz-dorado, e. farez-vidal, m. inouye, and s. inouye, j. bacteriol. 175:4756-4763, 1993). the amino-terminal 21 residues of mlpa encode a typical prokaryotic signal sequence with a putative lipoprotein cleavage site. when expressed in escherichia coli in the presence of [2-3h]glycerol, 3h-labeled mlpa had a molecular mass of 33 kda and was ... | 1995 | 8522522 |
| stimulation of endothelial cell growth by myxalin. | 1995 | 8528508 | |
| purification and in vitro phosphorylation of myxococcus xanthus asga protein. | the deduced amino acid sequence of the myxococcus xanthus asga protein contains an n-terminal domain that is homologous to the receiver of response regulators and a c-terminal domain that is homologous to the transmitter of histidine protein kinases. we overexpressed affinity-tagged asga in escherichia coli, purified the recombinant protein, and showed that asga has autokinase activity in vitro. the results of chemical-stability assays suggest that asga is phosphorylated on a histidine and provi ... | 1996 | 8550431 |
| mutants of myxococcus xanthus dsp defective in fibril binding. | the dsp mutant of myxococcus xanthus lacks extracellular fibrils and as a result is unable to undergo cohesion, group motility, or development (j. w. arnold and l. j. shimkets, j. bacteriol. 170:5765-5770, 1983; j. w. arnold and l. j. shimkets, j. bacteriol. 170:5771-5777, 1983; r. m. behmlander and m. dworkin, j. bacteriol. 173:7810-7821, 1991; l. j. shimkets, j. bacteriol. 166:837-841, 1986; l. j. shimkets, j. bacteriol. 166:842-848, 1986). however, cohesion and development can be phenotypical ... | 1996 | 8550502 |
| genetics of gliding motility and development in myxococcus xanthus. | successful development in multicellular eukaryotes requires cell-cell communication and the coordinated spatial and temporal movements of cells. the complex array of networks required to bring eukaryotic development to fruition can be modeled by the development of the simpler prokaryote myxococcus xanthus. as part of its life cycle, m. xanthus forms multicellular fruiting bodies containing differentiated cells. analysis of the genes essential for m. xanthus development is possible because strain ... | 1995 | 8572884 |
| starvation yields a drastic decrease in outer-membrane permeability to a periplasmic foreign protein in myxococcus xanthus. | a recombinant myxococcus xanthus strain was constructed that constitutively produces two proteins from escherichia coli, the cytoplasmic beta-galactosidase and the periplasmic ph 2.5 acid phosphatase (appa protein). we have previously shown that during vegetative growth, appa protein is partly accumulated in the periplasm of m. xanthus and partly released into the medium. we demonstrate here that during starvation-induced development, release of periplasmic appa protein to the medium did not occ ... | 1995 | 8574405 |
| suppression of a signaling defect during myxococcus xanthus development. | the csga gene encodes an extracellular protein that is essential for cell-cell communication (c-signaling) during fruiting body development of myxococcus xanthus. two transposon insertions in the socabc operon, soc-560 and socc559, restore development to csga null mutants. mixing soc-560 csga cells or socc559 csga cells with csga cells at a ratio of 1:1 stimulated the development of csga cells, suggesting that soc mutations allow cells to produce the c-signal or a similar molecule via a csga-ind ... | 1996 | 8576071 |
| the social behavior of myxobacteria. | myxobacteria are social microorganisms that undergo a spectacular cell cycle. under starvation conditions, cells aggregate to certain points originating macroscopic fruiting bodies, inside which cells differentiate into myxospores. to accomplish this developmental cycle, cells must communicate. the signals that cells exchange during development as well as the signal transduction systems used by myxobacteria have been intensively studied during the last years. a family of eukaryotic-like protein ... | 1995 | 8588838 |
| 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 o ... | 1995 | 8590393 |
| intercellular c-signaling in myxococcus xanthus involves a branched signal transduction pathway. | c-factor, the product of the csga gene, is a cell-surface associated short-range intercellular signaling protein in myxococcus xanthus. c-factor is required for at least four responses during starvation-induced fruiting body morphogenesis: rippling, aggregation, sporulation, and full expression of the csga gene, all of which fail in a csga mutant. to analyze the c-factor signaling pathway, eight tn5 lac insertion mutants that began but failed to complete fruiting body aggregation were characteri ... | 1996 | 8598300 |
| c factor, a cell-surface-associated intercellular signaling protein, stimulates the cytoplasmic frz signal transduction system in myxococcus xanthus. | c factor, an intercellular signaling protein, is required for aggregation and sporulation of the social bacterium, myxococcus xanthus. we report that c factor, which normally is associated with the cell surface, provides input to the frz signal transduction cascade. elements of this cascade have sequence homology to bacterial chemotaxis systems and are known to control the frequency of gliding reversal. exposure of developing cells of a c-factor-less mutant (csga) to purified c factor increases ... | 1996 | 8610100 |
| protoporphyrinogen oxidase of myxococcus xanthus. expression, purification, and characterization of the cloned enzyme. | protoporphyrinogen oxidase (ec 1.3.3.4) catalyzes the six electron oxidation of protoporphyrinogen ix to protoporphyrin ix. the enzyme from the bacterium myxococcus xanthus has been cloned, expressed, purified, and characterized. the protein has been expressed in escherichia coli using a tac promoter-driven expression plasmid and purified to apparent homogeneity in a rapid procedure that yields approximately 10 mg of purified protein per liter of culture. based upon the deduced amino acid sequen ... | 1996 | 8621504 |
| the myxococcus xanthus rfbabc operon encodes an atp-binding cassette transporter homolog required for o-antigen biosynthesis and multicellular development. | a wild-type sasa locus is critical for myxococcus xanthus multicellular development. mutations in the sasa locus cause defective fruiting body formation, reduce sporulation, and restore developmental expression of the early a-signal-dependent gene 4521 in the absence of a signal. the wild-type sasa locus has been located on a 14-kb cloned fragment of the m. xanthus chromosome. the nucleotide sequence of a 7-kb region containing the complete sasa locus was determined. three open reading frames en ... | 1996 | 8626291 |
| characterization of the regulatory region of a cell interaction-dependent gene in myxococcus xanthus. | omega 4403 is the site of a tn5 lac insertion in the myxococcus xanthus genome that fuses lacz expression to a developmentally regulated promoter. cell-cell interactions that occur during development, including c-signaling, are required for expression of tn5 lac omega 4403. we have cloned dna upstream of the omega 4403 insertion site, localized the promoter, and identified a potential open reading frame. from the deduced amino acid sequence, the gene disrupted by tn5 lac omega 4403 appears to en ... | 1996 | 8626320 |
| photolyase of myxococcus xanthus, a gram-negative eubacterium, is more similar to photolyases found in archaea and "higher" eukaryotes than to photolyases of other eubacteria. | we report the identification of the gene encoding a dna photolyase (phra) from the gram-negative eubacterium myxococcus xanthus. the deduced amino acid sequence of m. xanthus photolyase indicates that the protein contains 401 amino acids (mr 45,071). by comparison of the amino acid and dna sequences with those of other known photolyases, it has been found that it is more similar to the deduced amino acid sequences of the photolyases of "higher" eukaryotes than to the photolyases of other eubacte ... | 1996 | 8626418 |
| cell density regulates cellular reversal frequency in myxococcus xanthus. | myxococcus xanthus is a gram-negative bacterium that aggregates to form fruiting bodies when nutrients are limiting. previous studies showed that the frz mutants that are defective in chemotaxis exhibited irregular and infrequent patterns of cellular reversal. in contrast, wild-type cells, when examined individually, reverse relatively frequently, about once every 6 min. it is not known how the change of reversal frequency effects cellular aggregation during fruiting body formation in m. xanthus ... | 1996 | 8633030 |
| a method for the selective isolation of myxococcus directly from soil. | a new method is described for the selective isolation of species of myxococcus directly from soil by dilution plating. the method involves suppression of competing microorganisms with antibiotics combined with air drying and wet heat treatment of soils. fungi were eliminated by supplementing the plating medium with cycloheximide and nystatin. non-sporulating bacteria were controlled by air drying soils and then heating aqueous soil dilutions for 10 min at 56 degrees c. the predominant sporulatin ... | 1996 | 8652116 |
| gliding motility in slide cultures of myxococcus xanthus in stable and steep chemical gradients. | a method was devised to construct stable and steep chemical gradients in slide cultures to study the movements of gliding cells. the movement of myxococcus xanthus individual cells and small swarms was studied in these gradients. there was no response to gradients of casitone and yeast extract that were previously reported to stimulate a positive chemotactic response with m. xanthus. | 1996 | 8655544 |
| molecular cloning and characterization of ddcad-1, a ca2+-dependent cell-cell adhesion molecule, in dictyostelium discoideum. | dictyostelium discoideum expresses edta-sensitive cell-cell adhesion sites soon after the initiation of development, and a ca2+-binding protein of mr 24,000 (designated ddcad-1) has been implicated in this type of adhesiveness. we have previously purified ddcad-1 to homogeneity and characterized its cell binding activity (brar, s. k., and siu, c.-h. (1993) j. biol. chem. 268, 24902-24909). in this report, we describe the cloning of ddcad-1 cdnas. dna sequencing revealed a single open reading fra ... | 1996 | 8663243 |
| a r59w mutation in human protoporphyrinogen oxidase results in decreased enzyme activity and is prevalent in south africans with variegate porphyria. | variegate porphyria (vp), a low-penetrant autosomal dominant inherited disorder of haem metabolism, is characterised by photosensitivity (fig. 1) and a propensity to develop acute neuropsychiatric attacks with abdominal pain, vomiting, constipation, tachycardia, hypertension, psychiatric symptoms and, in the worst cases, quadriplegia. acute attacks, often precipitated by inappropriate drug therapy, are potentially fatal. while earlier workers thought the distal haem biosynthetic enzyme ferrochel ... | 1996 | 8673113 |
| a myxococcus xanthus cell density-sensing system required for multicellular development. | progression through early myxococcus xanthus multicellular fruiting body development requires the generation of and response to extracellular a signal. extracellular a signal is a specific set of amino acids at an extracellular concentration greater than 10 mum. it functions as a cell density signal during starvation that allows the cells to sense that a minimal cell density has been reached and development can proceed. the generation of extracellular a signal requires the products of three asg ... | 1996 | 8674994 |
| sequences of the salmonella typhimurium mgla and mglc genes. | the nucleotide sequences of the mgla and mglc genes of salmonella typhimurium (st) lt2 have been determined. the deduced amino acid (aa) sequences of mgla and mglc are 506 and 302 aa long with predicted molecular masses of 56,484 and 31,551 da, respectively. the aa sequences of st mgla and mglc are homologous to the corresponding mgl proteins of escherichia coli, haemophilus influenzae, treponema pallidum and mycoplasma genitalium. the order of the st mgl operon is mglbac. | 1996 | 8675022 |
| use of pcr to isolate genes encoding sigma54-dependent activators from diverse bacteria. | degenerate pcr probes were used to amplify gene fragments encoding the catalytic domain of sigma54-dependent transcription activators. the procedure should be widely applicable, as it recovered both known and novel gene fragments: 5 from rhizobium meliloti, 13 from myxococcus xanthus, and 3 from bacillus subtilis. no fragments were obtained from synechococcus sp. strain pcc 7002 or saccharomyces cerevisiae. | 1996 | 8682806 |
| high mobility group i(y)-like dna-binding domains on a bacterial transcription factor. | the bacterium myxococcus xanthus responds to blue light by producing carotenoids. it also responds to starvation conditions by developing fruiting bodies, where the cells differentiate into myxospores. each response entails the transcriptional activation of a separate set of genes. however, a single gene, card, is required for the activation of both light- and starvation-inducible genes. gene card has now been sequenced. its predicted amino acid sequence includes four repeats of a dna-binding do ... | 1996 | 8692912 |
| reciprocal regulation of the differentiation of myxococcus xanthus by pkn5 and pkn6, eukaryotic-like ser/thr protein kinases. | myxococcus xanthus contains a large family of genes encoding eukaryotic-like serine/threonine kinases. among them, two genes, pkn5 and pkn6, are divergently located on the chromosome and share a 46 bp promoter region between their transcription initiation sites, as determined by rna protection. pkn5, consisting of 380 amino acid residues, is a soluble protein in the cytoplasm, while pkn6, consisting of 710 amino acid residues, is a transmembrane protein. its membrane topology was determined usin ... | 1996 | 8733241 |
| identification and characterization of frzz, a novel response regulator necessary for swarming and fruiting-body formation in myxococcus xanthus. | the frz genes of myxococcus xanthus constitute a signal-transduction pathway that processes chemotactic information in a manner analogous to that found in enteric bacteria. ultimately, these genes regulate the frequency of individual cell reversal. we report here the identification of a novel component of this signal-transduction pathway, designated frzz, which was discovered as an open reading frame located 5' to the frz operon but transcribed in the opposite orientation. the translational star ... | 1996 | 8736543 |
| genetic and functional evidence that type iv pili are required for social gliding motility in myxococcus xanthus. | the social gliding behaviour of myxococcus xanthus has previously been associated with the presence of polar pili. a tn5 transposon insertion was isolated which introduces a defect in social gliding and is genetically linked to a known sgl locus; this insertion was found also to cause a piliation defect. a 2.7 kb section of dna was isolated from either side of this transposon and sequenced, revealing three genes which encode amino acid sequences with substantial similarity to components of the t ... | 1995 | 8748037 |
| secretion kinetics of endo-n-acetyl-beta-d-glucosaminidase during vegetative growth of myxococcus xanthus. | it was recently demonstrated that endo-n-acetyl-beta-d-glucosaminidases (engase) acting on n-glycosylproteins are produced by myxobacteria. in this study, it was shown that the secretion of engase during vegetative growth of myxococcus xanthus was cell-density-dependent. the activity produced per cell increased up to 6 x 10(8) cells/ml and stabilized thereafter (maximum level). two of the developmental mutants used in this study (bsga and csga) were locked for engase secretion into the maximum l ... | 1996 | 8763609 |
| integration of bacteriophage mx8 into the myxococcus xanthus chromosome causes a structural alteration at the c-terminal region of the intp protein. | mx8 is a generalized transducing phage that infects myxococcus xanthus cells. this phage is lysogenized in m. xanthus cells by the integration of its dna into the host chromosome through site-specific recombination. here, we characterize the mechanism of mx8 integration into the m. xanthus chromosome. the mx8 attachment site, attp, the m. xanthus chromosome attachment site, attb, and two phage-host junctions, attl and attr, were cloned and sequenced. sequence alignments of attp, attb, attl, and ... | 1996 | 8763924 |
| tyrosine phosphorylation in myxococcus xanthus, a multicellular prokaryote. | tyrosine phosphorylation is an extremely rare event in prokaryotes, occurring almost exclusively in multicellular eukaryotes. we have identified, for the first time, by the use of antiphosphotyrosine monoclonal antibody and western blot (immunoblot) analysis, two tyrosine-phosphorylated membrane proteins in the multicellular prokaryote myxococcus xanthus. the pattern of tyrosine phosphorylation was shown to change during development, indicating a possible role for this regulatory modification du ... | 1996 | 8763935 |
| light-induced carotenogenesis in myxococcus xanthus: light-dependent membrane sequestration of ecf sigma factor carq by anti-sigma factor carr. | light-induced carotenogenesis in myxococcus xanthus is under the control of the carqrs operon. carq, a proposed extracytoplasmic (ecf) rna polymerase sigma factor, is required for expression of the operon and the carc gene that encodes phytoene dehydrogenase. carr, an inner membrane protein in escherichia coli, is essential for carqrs promoter inactivation in the dark. cars is required for the light-dependent expression of the promoter of the carb gene cluster that encodes the rest of the struct ... | 1996 | 8821946 |
| propagation of traveling waves in excitable media. | 1996 | 8824584 | |
| markerless deletions of pil genes in myxococcus xanthus generated by counterselection with the bacillus subtilis sacb gene. | in-frame deletions of pila and pils were constructed in myxococcus xanthus with a plasmid integration-excision strategy facilitated by sacb. sacb conferred sucrose sensitivity upon its m. xanthus host only when it lay in the same orientation as adjacent m. xanthus genes. gene orientation also affected the efficiency of sucrose counterselection in the sucrose-sensitive strains. the deltapila mutant lacked pili and social motility, while the deltapils mutant showed no defect in either phenotype. | 1996 | 8824635 |
| a missense mutation in rpod results in an a-signalling defect in myxococcus xanthus. | the myxococcus xanthus asg genes (asga, asgb, and asgc) are necessary for production of extracellular a-signal, which is thought to function as a cell-density signal. previous analyses of the asga and asgb genes suggest that they perform regulatory functions. in this work, we localized asgc to a region that contains genes homologous to rpsu, dnag, and rpod of the escherichia coli macromolecular synthesis (mms) operon. surprisingly, asgc767 was found to be a mutant allele of rpod, the gene encodi ... | 1995 | 8825098 |
| defect in export and synthesis of the periplasmic galactose receptor mglb in dnak mutants of escherichia coli, and decreased stability of the mglb mrna. | the high-affinity galactose permease, which comprises the periplasmic galactose receptor mglb, the membrane translocator mglc and the membrane-associated atpase mgla, displayed a reduced activity in a dnak temperature-sensitive mutant of escherichia coli. this reduced transport activity correlated with a reduction in the quantity of mglb. at 42 degrees c, an accumulation of pre-mglb in the dnak temperature-sensitive mutant reflected a defect in mglb export. in addition, an accumulation of pre-mg ... | 1996 | 8828228 |
| sequence and analysis of a 33 kb fragment from the right arm of chromosome xv of the yeast saccharomyces cerevisiae. | we have determined the nucleotide sequence of a cosmid (peoa423) from chromosome xv of saccharomyces cerevisiae. analysis of the 33,173 bp sequence reveals the presence of 20 putative open reading frames (orfs). five of them correspond to previously known genes (mgm1, ste4, cdc44, ste13, rpb8). the previously published nucleotide sequences are in perfect agreement with our sequence except for ste4 and mgm1. in the latter case, 59 amino acids were truncated from the published protein at its n-ter ... | 1996 | 8840505 |
| bacterial signalling involving eukaryotic-type protein kinases. | protein ser, thr and tyr kinases play essential roles in signal transduction in organisms ranging from yeast to mammals, where they regulate a variety of cellular activities. during the last few years, a number of genes that encode eukaryotic-type protein kinases have also been identified in four different bacterial species, suggesting that such enzymes are also widespread in prokaryotes. although many of them have yet to be fully characterized, several studies indicate that eukaryotic-type prot ... | 1996 | 8861199 |
| a mgl-like operon in treponema pallidum, the syphilis spirochete. | a 38-kda lipoprotein of treponema pallidum subsp. pallidum (t. pallidum), the syphilis spirochete, previously was identified as a putative homolog of e. coli mglb [becker et al. (1994) infect. immun. 62, 1381-1391]. in the present study, genome walking in regions adjacent to the t. pallidum 38-kda lipoprotein gene has identified three contiguous genes (tp-mglb [formerly tpp38], tp-mgla, and tp-mglc) which appear to comprise a mgl-like operon in t. pallidum. a prominent transcript corresponding t ... | 1996 | 8921855 |
| the myxococcus xanthus developmentally expressed asgb-dependent genes can be targets of the a signal-generating or a signal-responding pathway. | functional myxococcus xanthus a signal-generating and a signal-responding pathways are required for the progression through early multicellular development. to identify genes responsive to these pathways, the expression of eight early developmental genes was analyzed. this examination identified one gene as a target of the a signal-generating pathway and four genes as targets of the a signal-responding pathway. | 1996 | 8932321 |
| effects of overexpression of pkn2, a transmembrane protein serine/threonine kinase, on development of myxococcus xanthus. | pkn2 is a putative transmembrane protein serine/threonine kinase required for normal development of myxococcus xanthus. the effect of pkn2 overexpression on development of m. xanthus was examined by expressing pkn2 under the control of a kanamycin promoter. pkn2 was clearly detected by western blot (immunoblot) analysis in the overexpression strain (the pkm/pkn2 strain) but could not be detected in the wild-type strain. overexpressed pkn2 was located almost exclusively in the membrane fraction, ... | 1996 | 8932326 |
| two multifunctional peptide synthetases and an o-methyltransferase are involved in the biosynthesis of the dna-binding antibiotic and antitumour agent saframycin mx1 from myxococcus xanthus. | saframycin mx1 is a dna-binding antibiotic and antitumour agent produced by myxococcus xanthus. it is a heterocyclic quinone, thought to be synthesized via the linear peptide intermediate alaglytyrtyr. analysis of 14.1 kb dna sequence involved in saframycin production revealed genes for two large multifunctional peptide synthetases of 1770 and 2605 amino acids, respectively, and a putative o-methyltransferase of 220 amino acids. the three orfs read in the same direction and are separated by shor ... | 1996 | 8936303 |
| frua, a putative transcription factor essential for the development of myxococcus xanthus. | a new developmental gene, frua, of myxococcus xanthus was cloned using a one-step cloning vector, tnv. dna sequencing of the wild-type allele of the frua gene indicated that the frua gene encodes a protein of 229 amino acid residues with a calculated molecular weight of 24672. the deduced amino acid sequence of frua protein showed similarity to those of many bacterial regulatory proteins carrying a dna-binding helix-turn-helix motif. the transcription-initiation site of the frua gene was determi ... | 1996 | 8951822 |
| identification and sequences of the treponema pallidum mgla and mglc genes. | treponema pallidum, the agent of syphilis, cannot be continuously cultivated in vitro. to identify treponemal genes encoding exported proteins, we performed tnphoa mutagenesis of a t. pallidum genomic dna library in escherichia coli. clone 6d2 was chosen for further study based on partial nucleotide sequence obtained from p6d2 containing a tnphoa insertion. a complete open reading frame (orf1) and a truncated orf (orf2) were identified in the treponemal dna of p6d2. orf1 encodes a hydrophobic pr ... | 1996 | 8988365 |
| positive-negative kg cassettes for construction of multi-gene deletions using a single drug marker. | positive-negative kg cassettes were developed in order to create a number of independent deletion mutations on the bacterial chromosome using a single drug marker. these cassettes consist of a kanamycin-resistant (kmr) gene for positive screening and a galactokinase gene (galk) for negative screening. both genes are in an operon driven by the native kmr promoter and are flanked by identical fragments of yeast chromosomal dna approximately one kb in size. an internal region of a cloned target gen ... | 1996 | 8996101 |
| behavioral analysis of single cells of myxococcus xanthus in response to prey cells of escherichia coli. | myxococcus xanthus cells move over surfaces by gliding motility. the frz signal transduction system is used to control the reversal frequency, and thus the overall direction of movement of m. xanthus cells. we analyzed the behavior of wild-type and frz mutant cells in response to prey bacteria (escherichia coli). wild-type cells of m. xanthus did not respond to microcolonies of e. coli until they made physical contact. cells which penetrated a colony remained in the colony until all of the prey ... | 1996 | 8998990 |
| why and how bacteria communicate. | 1997 | 9000763 | |
| biochemical characterization of pkn2, a protein ser/thr kinase from myxococcus xanthus, a gram-negative developmental bacterium. | pkn2, a protein ser/thr kinase, from the developmental bacterium myxococcus xanthus was expressed under a t7 promoter in escherichia coli and purified. purified pkn2 retained the autophosphorylation activity with the km value of 177 microm for atp and 73 nmol/min/mg for vmax. the optimum ph and temperature were determined to be 7.5 and 35 degrees c, respectively. the autophosphorylation activity was inhibited by staurosporine with the ic50 value of 400 nm while h-7 and genistein had little effec ... | 1997 | 9001395 |
| the myxococcus xanthus pilt locus is required for social gliding motility although pili are still produced. | social gliding motility in myxococcus xanthus depends on the presence of type iv pili. to begin to examine the role of pili in social motility, 17 mutants were identified which had lost social motility, but still expressed pili. four of these mutants carry point mutations which mapped to a locus upstream of the recently identified pils, pilr, and pila genes. sequencing of this locus revealed a gene with homology to pilt from pseudomonas aeruginosa. sequencing of the four point mutations revealed ... | 1997 | 9004225 |
| characterization of csga, a new member of the forespore-expressed sigmag-regulon from bacillus subtilis. | a new locus, csga, has been identified in a search for developmental genes transcribed by e sigmag in bacillus subtilis. csga has the potential to encode three small proteins, csgaa, csgab and csgac. the latter two would be encoded by overlapping orfs. csga is expressed in the spore chamber of the differentiating cell and is under the control of sigmag and the transcriptional regulatory protein spovt. mutation of csga did not affect spore formation but produced a subtle defect in the ability of ... | 1997 | 9016963 |
| further characterization and in situ localization of chain-like aggregates of the gliding bacteria myxococcus fulvus and myxococcus xanthus. | for the first time, chain-like aggregates, called "strands," have been enriched from crude cell wall preparations of liquid-grown vegetative cells of two strains of myxococcus xanthus. these strands are highly isomorphic to macromolecular structures, previously described for myxococcus fulvus (lünsdorf and reichenbach, j. gen. microbiol. 135:1633-1641, 1989). the strands are morphologically composed of ring elements, consisting of six or more peripheral protein masses and possibly three small ce ... | 1997 | 9023208 |
| adp-ribosylation by the extracellular fibrils of myxococcus xanthus. | the isolated, extracellular fibrils of the myxobacterium, myxococcus xanthus, are capable of carrying out adp-ribosylation. the substrate for the adp-ribosylation is reactive with monoclonal antibody 2105, which has been shown to be directed specifically against the integral fibril proteins. the extracellular fibrils thus contain both the adp-ribosyl transferase and the substrate for the ribosylation. this process may play a role in the contact-mediated cell-cell interactions that are an importa ... | 1997 | 9044257 |
| pkn9, a ser/thr protein kinase involved in the development of myxococcus xanthus. | the myxococcus xanthus gene, pkn9, encodes a protein that contains significant homology with eukaryotic ser/thr protein kinases. the pkn9 gene was singled out of a previously identified family of kinase genes by amplification techniques that displayed differences in kinase gene expression during selected periods of the m. xanthus life cycle. pkn9 was constitutively expressed during vegetative growth and upregulated during the aggregation stage of early development. it consists of 589 amino acids ... | 1997 | 9044280 |
| sigma54, a vital protein for myxococcus xanthus. | the rpon gene encoding the transcription factor sigma54 in myxococcus xanthus has been cloned using a heterologous rpon probe. the sequence of the cross-hybridizing dna confirmed the existence of an orf 1518 bp long that encodes a well conserved member of the sigma54 family of sigma factors. low- as well as high-stringency hybridizations detected only a single rpon gene in the m. xanthus chromosome. in other bacteria, sigma54 is an alternative sigma, and null mutants are viable. however, all att ... | 1997 | 9050890 |
| a gene involved in both protein secretion during growth and starvation-induced development encodes a subunit of the nadh:ubiquinone oxidoreductase in myxococcus xanthus. | the secretion of numerous proteins during vegetative growth of myxococcus xanthus, and the multicellular development cycle induced upon starvation of these bacteria, are partially interrelated in so far as mutants impaired in extracellular protein production are unable to undergo development. we have cloned and sequenced a gene in which a tn5 insertion leads to a decrease in the production of most, if not all, extracellular proteins, and prevents development and sporulation. the deduced protein ... | 1997 | 9076740 |
| identification and characterization of myxococcus xanthus mutants deficient in calcofluor white binding. | calcofluor white is a fluorescent dye that binds to glycans and can be used to detect extracellular polysaccharide in myxococcus xanthus and many other bacteria. we observed that an esg mutant showed less binding to calcofluor white than wild-type cells. unlike s-motility mutants that share this phenotypic characteristic, the esg mutant exhibited s motility. this led us to identify a collection of nine new transposon insertion mutants, designated cds (for calcofluor white binding deficient and s ... | 1997 | 9139901 |
| starvation-independent sporulation in myxococcus xanthus involves the pathway for beta-lactamase induction and provides a mechanism for competitive cell survival. | myxococcus xanthus is a gram-negative, soil-dwelling bacterium with a complex life cycle which includes fruiting body formation and sporulation in response to starvation. this developmental process is slow, requiring a minimum of 24-48 h, and requires cells to be at high cell density on a solid surface. it is known that, in the absence of starvation, vegetatively growing cell suspensions can form 'glycerol spores' when exposed to high levels of glycerol, usually 0.5 m. the cells differentiate fr ... | 1997 | 9194710 |
| temperate myxococcus xanthus phage mx8 encodes a dna adenine methylase, mox. | temperate bacteriophage mx8 of myxococcus xanthus encapsidates terminally repetitious dna, packaged as circular permutations of its 49-kbp genome. during both lytic and lysogenic development, mx8 expresses a nonessential dna methylase, mox, which modifies adenine residues in occurrences of xhoi and psti recognition sites, ctcgag and ctgcag, respectively, on both phage dna and the host chromosome. the mox gene is necessary for methylase activity in vivo, because an amber mutation in the mox gene ... | 1997 | 9209041 |
| the tgl gene: social motility and stimulation in myxococcus xanthus. | mutations in the tgl locus inactivate social gliding motility in myxococcus xanthus and block production of pili. the tgl locus is distinctive among the genes for social motility because social gliding and pili can be restored transiently to tgl mutant cells by mixing them with tgl+ cells, a process known as stimulation. the tgl locus was cloned with a linked insertion of transposon tn5 by using the kanamycin resistance encoded by that transposon. a 16-kb segment of chromosomal dna complemented ... | 1997 | 9209055 |
| identification and localization of the tgl protein, which is required for myxococcus xanthus social motility. | tgl protein is required for the production of the type iv pili found at a pole of the myxococcus xanthus cell. these pili are essential for social motility. evidence is presented that tgl is a membrane protein, based on experiments with polyclonal antibody specific for tgl that was raised against the fusion proteins beta-galactosidase-tgl and trpe-tgl. immunoaffiity-purified antibody reacted with a protein in m. xanthus having an apparent molecular mass of 27.5 kda as measured by sodium dodecyl ... | 1997 | 9209056 |
| regulation of directed motility in myxococcus xanthus. | myxococcus xanthus is a gram-negative bacterium that exhibits a complex life cycle. during vegetative growth, cells move as large swarms. however, when starved, cells aggregate into fruiting bodies and sporulate. both vegetative swarming and developmental aggregation require gliding motility, which involves the slow movement of cells on a solid surface in the absence of flagella. the frequency of cell reversals controls the direction of movement and is regulated by the frz genes, which encode th ... | 1997 | 9219997 |
| molecular genetic analysis of type-4 pilus biogenesis and twitching motility using pseudomonas aeruginosa as a model system--a review. | genetic analysis of pseudomonas aeruginosa pilus biogenesis and twitching motility has revealed the requirement for several pil loci which have been localized to different regions of the chromosome. one pil locus, designated pile, resides at approx. 71 min on the pao genetic map, a region of the chromosome previously shown to harbor a number of genes required for pilus assembly (i.e., pila, -b, -c, -d, -r and -s). the pile protein shows significant sequence identity to the n-terminal domain of p ... | 1997 | 9224880 |
| complementation of sporulation and motility defects in a prokaryote by a eukaryotic gtpase. | the complex prokaryote, myxococcus xanthus, undergoes a program of multicellular development when starved for nutrients, culminating in sporulation. m. xanthus makes mgla, a 22-kda, soluble protein that is required for both multicellular development and gliding motility. mgla is similar in sequence to the saccharomyces cerevisiae sar1 protein, a member of the ras/rab/rho superfamily of small eukaryotic gtpases. the sar1 gene, when integrated into the m. xanthus genome, complements the sporulatio ... | 1997 | 9275220 |
| a crtb homolog essential for photochromogenicity in mycobacterium marinum: isolation, characterization, and gene disruption via homologous recombination. | a gene essential for light-induced pigment production was isolated from the photochromogen mycobacterium marinum by heterologous complementation of an m. marinum cosmid library in the nonchromogen mycobacterium smegmatis. this gene is part of an operon and homologous to the streptomyces griseus and myxococcus xanthus crtb genes encoding phytoene synthase. gene replacement at this locus was achieved via homologous recombination, demonstrating that its expression is essential for photochromogenici ... | 1997 | 9294446 |
| in vitro transcription of myxococcus xanthus genes with rna polymerase containing sigmaa, the major sigma factor in growing cells. | myxococcus xanthus is a gram-negative bacterium that undergoes multicellular development upon starvation. we have developed a simple and rapid procedure for partial purification of rna polymerase from growing m. xanthus cells, using heparin-agarose and dna-cellulose chromatographies. in addition to core subunits, the enzyme contains one fairly abundant polypeptide of approximately 105 kda. we have shown by western blot analysis and protein sequencing that the 105-kda polypeptide is sigmaa, the p ... | 1997 | 9302009 |
| picture story. an eye on crystallins. | 1997 | 9302991 | |
| sequence of the bacillus subtilis genome region in the vicinity of the lev operon reveals two new extracytoplasmic function rna polymerase sigma factors sigv and sigz. | two regions with sizes 18,900 and 25,400 bp, which join previously known contigs containing levrdefg, aadk and blt genes near 235 degrees of the bacillus subtilis chromosome, were sequenced. among others, two genes, which encode proteins homologous to rna polymerase sigma-factors, were identified within this region. the gene products designated sigv and sigz, show the highest homology with sigma-factors encoded by the gene carq of myxococcus xanthus and sigx (formerly orfx20) of b. subtilis, cor ... | 1997 | 9308178 |
| trans-acting regulation of antibiotic ta genes in myxococcus xanthus. | two regulatory mutations of myxococcus xanthus, which cause an increase in the transcription of genes required for antibiotic ta synthesis, were mapped by transduction and their effect on transcription of four ta genes examined. the two regulatory mutations were closely linked and located within the 40-kb ta gene cluster on the m. xanthus chromosome. recombinants were constructed which contained one of the regulatory mutations and promoter probes in the four different ta genes. both regulatory m ... | 1997 | 9351195 |
| cloning and sequencing of two genes, prta and prtb, from myxococcus xanthus, encoding prta and prtb proteases, both of which are required for the protease activity. | the sequence of a 1955-bp taqi dna fragment from myxococcus xanthus was determined. this fragment contains two complete genes, designated prta and prtb. the prta and prtb orfs extend over 828 and 798 bp, respectively. they are separated only by 3 nt and appear to be present in a polycistronic transcriptional unit. a typical lipoprotein signal sequence is present at the n terminus of the two deduced polypeptides. the aa sequence of prta shows a high degree of identity to the region adjacent to th ... | 1997 | 9370274 |
| propionyl coenzyme a carboxylase is required for development of myxococcus xanthus. | a dcm-1 mutant, obtained by transposon mutagenesis of myxococcus xanthus, could aggregate and form mounds but was unable to sporulate under nutrient starvation. a sequence analysis of the site of insertion of the transposon showed that the insertion lies within the 3' end of a 1,572-bp open reading frame (orf) designated the m. xanthus pccb orf. the wild-type form of the m. xanthus pccb gene, obtained from a lambdaembl library of m. xanthus, shows extensive similarity to a beta subunit of propio ... | 1997 | 9371458 |
| comparative heavy metal biosorption study of brewery yeast and myxococcus xanthus biomass. | the biosorption for la2+, co2+, mn2+, uo2(2+), pb2+, ag+, zn2+, cd2+ and cr2+ by wet and dry biomass form myxococcus xanthus obtained from laboratory cultures and saccharomyces cerevisiae from the brewing industry has been studied. m. xanthus biomass was found to be the most efficient biosorbent for all of the metals assayed. however, due to the fact that s. cerevisiae is a low cost residual by-product from the brewing industry, and at the same time yields good levels of biosorption, it is consi ... | 1997 | 9375355 |
| rapid purification and characterization of nucleoside diphosphate kinase isoforms using atp-sepharose affinity column chromatography. | nucleoside diphosphate kinases (ndp kinases), products of the nm23 gene, catalyze the transfer of the terminal phosphate group of the nucleoside triphosphate to the corresponding diphosphate and may be involved in tumor metastasis suppression, development, and signal transduction. ndp kinase from various sources including human erythrocytes, rat brain tissue and e. coli strain bl21 transformed with pet3c expression plasmids containing nm23-h1 or nm23-h2, were purified in one step to homogeneity ... | 1997 | 9387150 |
| a regulatory locus, pehsr, controls polygalacturonase production and other virulence functions in ralstonia solanacearum. | we previously identified a locus that regulates production of polygalacturonase (pg), an extracellular plant cell wall-degrading enzyme important in bacterial wilt of plants caused by ralstonia (pseudomonas) solanacearum. the dna sequence of this locus, called pehsr, was determined and two consecutive open reading frames (orfs) of 1,905 and 1,680 bp were identified. the amino acid sequences predicted to be encoded by these orfs are similar to those of regulators of pilin synthesis in pseudomonas ... | 1997 | 9390420 |
| regulation of expression of the pila gene in myxococcus xanthus. | type iv pili are required for social gliding motility in myxococcus xanthus. in this work, the expression of pilin (the pila gene product) during vegetative growth and fruiting-body development was examined. a polyclonal antibody against the pila gene product (prepilin) was prepared, along with a pila-lacz fusion, and was used to assay expression of pila in m. xanthus in different mutant backgrounds. pila expression required the response regulator pilr but was negatively regulated by the putativ ... | 1997 | 9401034 |
| myxococcus xanthus sass encodes a sensor histidine kinase required for early developmental gene expression. | initiation of myxococcus xanthus multicellular development requires integration of information concerning the cells' nutrient status and density. a gain-of-function mutation, sasb7, that bypasses both the starvation and high cell density requirements for developmental expression of the 4521 reporter gene, maps to the sass gene. the wild-type sass gene was cloned and sequenced. this gene is predicted to encode a sensor histidine protein kinase that appears to be a key element in the transduction ... | 1997 | 9401035 |
| a mutation that affects fibril protein, development, cohesion and gene expression in myxococcus xanthus. | extracellular matrix fibrils are involved in the cell-cell interactions of the social prokaryote, myxococcus xanthus. the fibrils are composed of a carbohydrate backbone and a set of five integral fibrillar proteins (ifps) ranging from 14 to 66 kda. as part of an attempt to understand the function(s) of the ifps, a mutant (ifp-1:20) was generated that lacks ifp-1:20, one of the fibril proteins, as shown by western blot analysis of both whole cells and isolated fibrils. unlike those of the parent ... | 1997 | 9421894 |
| a dnak homolog in myxococcus xanthus is involved in social motility and fruiting body formation. | myxococcus xanthus is a gram-negative soil bacterium which exhibits a complex life cycle and social behavior. in this study, two developmental mutants of m. xanthus were isolated through tn5 transposon mutagenesis. the mutants were found to be defective in cellular aggregation as well as in sporulation. further phenotypic characterization indicated that the mutants were defective in social motility but normal in directed cell movements. both mutations were cloned by a transposon-tagging method. ... | 1998 | 9440508 |
| myxococcus xanthus displays frz-dependent chemokinetic behavior during vegetative swarming. | myxococcus xanthus has been shown to utilize both directed (tactic) and undirected (kinetic) movements during different stages of its complex life cycle. we have used time-lapse video microscopic analysis to separate tactic and kinetic behaviors associated specifically with vegetatively swarming cells. isolated individual cells separated by a thin agar barrier from mature swarms showed significant increases in gliding velocity compared to that of similar cells some distance from the swarm. this ... | 1998 | 9440539 |
| genetic determinants of immunity and integration of temperate myxococcus xanthus phage mx8. | an 8.1-kb fragment of the temperate myxococcus xanthus phage mx8 genome, when cloned into a plasmid vector, permits site-specific integration of the plasmid and confers superinfection immunity. sequence analysis of a 9.5-kb region of mx8 dna containing this fragment reveals 19 densely packed open reading frames, four of which have predicted products with known or suspected activities. the mx8 imm gene, required for superinfection immunity, has a sequence similar to that of arabidopsis thaliana g ... | 1998 | 9457865 |
| contact stimulation of tgl and type iv pili in myxococcus xanthus. | myxococcus xanthus tgl mutants lack social motility and type iv pili but can be transiently stimulated to swarm and to make pili by contacting tgl+ cells. the absence of pili in tgl mutants is shown not to be due to the absence of pilin. the rate of pilus elongation after tgl stimulation is shown to be similar to the rate of pilus elongation in wild-type cells, using a new more rapid assay for stimulation. | 1998 | 9457887 |
| alignment enhances the cell-to-cell transfer of pilus phenotype. | social gliding motility of myxococcus xanthus requires polar type iv pili. tgl mutants lack pili and lack social motility. however, both defects can be rescued phenotypically, but not genotypically, when tgl+ donor and tgl- recipient cells make physical contact with each other. what is the cellular and molecular basis of this transfer of phenotype, which is called stimulation? stimulation does not occur in liquid nor in soft (0.5%) agar; however, on a more firm surface (1.0% agar) cells stimulat ... | 1998 | 9501214 |
| the guanosine nucleotide (p)ppgpp initiates development and a-factor production in myxococcus xanthus. | guanosine 3'-di-5'-(tri)di-phosphate nucleotides [(p)ppgpp], synthesized in response to amino acid limitation, induce early gene expression leading to multicellular fruiting body formation in myxococcus xanthus. a mutant (dk527) that fails to accumulate (p)ppgpp in response to starvation was found to be blocked in development prior to aggregation. by use of a series of developmentally regulated tn5lac transcriptional fusion reporters, the time of developmental arrest in dk527 was narrowed to wit ... | 1998 | 9531539 |
| identification of the omega4400 regulatory region, a developmental promoter of myxococcus xanthus. | omega4400 is the site of a tn5 lac insertion in the myxococcus xanthus genome that fuses lacz expression to a developmentally regulated promoter. cell-cell interactions that occur during development, including c signaling, are required for normal expression of tn5 lac omega4400. the dna upstream of the omega4400 insertion has been cloned, the promoter has been localized, and a partial open reading frame has been identified. from the deduced amino acid sequence of the partial open reading frame, ... | 1998 | 9555878 |
| identification of an fad superfamily containing protoporphyrinogen oxidases, monoamine oxidases, and phytoene desaturase. expression and characterization of phytoene desaturase of myxococcus xanthus. | a large number of fad-containing proteins have previously been shown to contain a signature sequence that is referred to as the dinucleotide binding motif. protoporphyrinogen oxidase (ppo), the penultimate enzyme of the heme biosynthetic pathway, is an fad-containing protein that catalyzes the six electron oxidation of protoporphyrinogen ix. sequence analysis demonstrates the presence of the dinucleotide binding motif at the amino-terminal end of the protein. analysis of the current data base re ... | 1998 | 9593705 |
| bacterial motility: secretory secrets of gliding bacteria. | many bacteria glide over surfaces without the aid of flagella. gliding is still somewhat mysterious, but recent studies show that it involves specialized secretory systems that assemble membrane-associated filaments, and the recognition of extracellular components that trigger movement via transmembrane transducers. | 1998 | 9637910 |
| molecular analysis of the dna gyrb gene from myxococcus xanthus. | dna gyrase, an essential type ii topoisomerase, mediates negative supercoiling of the bacterial chromosome, thereby affecting the processes of dna replication, transcription, recombination and repair. the gyrb gene from the gram-negative soil bacterium myxococcus xanthus was sequenced. the sequence predicts a protein of 815 amino acid residues displaying significant homology to all known gyrb proteins. a 6-his-gyrb fusion protein was overexpressed in escherichia coli and purified to near homogen ... | 1998 | 9639935 |
| the extracytoplasmic function sigma factors: role and regulation. | alternative sigma factors provide a means of regulating gene expression in response to various extracellular changes. one such class of sigma factors appears to control a variety of functions, including expression of heat-shock genes in escherichia coli, biosynthesis of alginates and carotenoids in pseudomonas aeruginosa and myxococcus xanthus, respectively, iron uptake in e. coli and pseudomonas spp., nickel and cobalt efflux in alcaligenes europhus, plant pathogenicity in pseudomonas syringae ... | 1998 | 9680198 |
| propionyl-coa carboxylase of myxococcus xanthus: catalytic properties and function in developing cells. | an acyl-coenzyme a carboxylase that carboxylates acetyl-coa, butyryl-coa, propionyl-coa, and succinyl-coa was purified from myxococcus xanthus. since the enzyme showed maximal rates of carboxylation with propionyl-coa, the enzyme is thought to be propionyl-coa carboxylase. the apparent km values for acetyl-coa, butyryl-coa, propionyl-coa, and succinyl-coa were found to be 0.2, 0. 2, 0.03, and 1.0 mm, respectively. the native enzyme has a molecular mass of 605-615 kda and is composed of nonidenti ... | 1998 | 9683657 |
| mgla and mglb are required for the intramacrophage growth of francisella novicida. | francisella novicida is a facultative intracellular pathogen capable of growing in macrophages. a spontaneous mutant of f. novicida defective for growth in macrophages was isolated on lb media containing the chromogenic phosphatase substrate 5-bromo-4-chloro-3-indolyl phosphate (x-p) and designated gb2. using an in cis complementation strategy, four strains were isolated that are restored for growth in macrophages. a locus isolated from one of these strains complements gb2 for both the intracell ... | 1998 | 9701818 |
| pilt mutations lead to simultaneous defects in competence for natural transformation and twitching motility in piliated neisseria gonorrhoeae. | neisseria gonorrhoeae, the gram-negative aetiological agent of gonorrhoeae, is one of many mucosal pathogens of man that expresses competence for natural transformation. expression of this phenotype by gonococci appears to rely on the expression of type iv pili (tfp), but the mechanistic basis for this relationship remains unknown. during studies of gonococcal pilus biogenesis, a homologue of the pilt family of proteins, required for tfp-dependent twitching motility in pseudomonas aeruginosa and ... | 1998 | 9701824 |
| sdek is required for early fruiting body development in myxococcus xanthus. | myxococcus xanthus cells carrying the omega4408 tn5lac insertion at the sde locus show defects in fruiting body development and sporulation. our analysis of sde expression patterns showed that this locus is induced early in the developmental program (0 to 2 h) and that expression increases approximately fivefold after 12 h of development. further studies showed that expression of sde is induced as growing cells enter stationary phase, suggesting that activation of the sde locus is not limited to ... | 1998 | 9721305 |
| a new sigma factor, sigd, essential for stationary phase is also required for multicellular differentiation in myxococcus xanthus. | myxococcus xanthus is a gram-negative bacterium that undergoes spectacular development to form multicellular fruiting bodies under nutrient deprivation. inside a fruiting body, vegetative cells differentiate into spores. a number of sigma factors have been shown to play roles in the regulation of gene expression in the m. xanthus life cycle. additional sigma factors were searched to further explore the m. xanthus life cycle. | 1998 | 9734783 |
| myxococcus xanthus spore coat protein s, a stress-induced member of the betagamma-crystallin superfamily, gains stability from binding of calcium ions. | protein s, a calcium-binding spore coat protein from the soil bacterium myxococcus xanthus, belongs to a group of structurally related proteins, the betagamma-crystallin superfamily. common features of this protein family are the greek-key structural motif or crystallin fold, and the fact that all members are extremely stable long term. to investigate the correlation between the stability and greek-key topology, protein s was cloned, expressed in escherichia coli and purified to homogeneity. ca2 ... | 1998 | 9738899 |