| nutrient regulation of epothilone biosynthesis in heterologous and native production strains. | fermentation media with different initial concentrations of ammonium and phosphate salts were used to study the inhibitory effects of those ions on growth and production of epothilone in sorangium cellulosum and myxococcus xanthus. the native epothilone producer, s. cellulosum was more sensitive to ammonium and phosphate than the heterologous producer, m. xanthus. an ammonium concentration of 12 mm reduced epothilone titers by 90% in s. cellulosum but by only 40% in m. xanthus. when 5 mm phospha ... | 2003 | 12764559 |
| the stigmatella aurantiaca homolog of myxococcus xanthus high-mobility-group a-type transcription factor card: insights into the functional modules of card and their distribution in bacteria. | transcriptional factor card is the only reported prokaryotic analog of eukaryotic high-mobility-group a (hmga) proteins, in that it has contiguous acidic and at hook dna-binding segments and multifunctional roles in myxococcus xanthus carotenogenesis and fruiting body formation. hmga proteins are small, randomly structured, nonhistone, nuclear architectural factors that remodel dna and chromatin structure. here we report on a second at hook protein, card(sa), that is very similar to card and tha ... | 2003 | 12775690 |
| phor1, a gene encoding a new histidine protein kinase myxococcus xanthus. | a soil bacterium able to undergo multicellular development and a coordinated gliding in swarms, requires an accurate regulatory network of phosphorelay proteins. inorganic phosphate is a limiting nutrient in soil and its importance in regulation is critical. as a step towards studying phosphate regulation and its influence in the developmental process in this bacterium, we screened a myxococcus xanthus library for clones with phosphatase activity, and found four different ones. the deduced seque ... | 2003 | 12777072 |
| production of cellulose and curli fimbriae by members of the family enterobacteriaceae isolated from the human gastrointestinal tract. | citrobacter spp., enterobacter spp., and klebsiella spp. isolated from the human gut were investigated for the biosynthesis of cellulose and curli fimbriae (csg). while citrobacter spp. produced curli fimbriae and cellulose and enterobacter spp. produced cellulose with various temperature-regulatory programs, klebsiella spp. did not show pronounced expression of those extracellular matrix components. investigation of multicellular behavior in two citrobacter species and enterobacter sakazakii sh ... | 2003 | 12819107 |
| taxing questions in development. | bacteria use taxis-controlled movement to reach their optimum environment. chemotaxis is probably the best understood behavioural system in biology, biasing the normal random movement of bacteria using a phospho-relay pathway from receptors to the motility organelles. the pathways are typified by signal recognition and receptor adaptation, enabling bacteria to sense and respond to changing environments. models have been derived from the single chemosensory pathway of escherichia coli but the seq ... | 2003 | 12823935 |
| an effective sporulation of myxococcus xanthus requires glycogen consumption via pkn4-activated 6-phosphofructokinase. | 6-phosphofructokinase (pfk) is a key enzyme for glycolysis in both prokaryotes and eukaryotes. previously, it was found that the activity of myxococcus xanthus pfk increased 2.7-fold upon phosphorylation at thr-226 by the ser/thr kinase pkn4. the pkn4 gene is located 18 bp downstream of the pfk gene forming an operon, and both genes are expressed during vegetative growth and development. here, we show that glycogen, which accumulates during stationary phase and early in development, is consumed ... | 2003 | 12828646 |
| identification of genes required for adventurous gliding motility in myxococcus xanthus with the transposable element mariner. | myxococcus xanthus glides over solid surfaces without the use of flagella, dependent upon two large sets of adventurous (a) and social (s) genes, using two different mechanisms of gliding motility. myxococcus xanthus a-s- double mutants form non-motile colonies lacking migratory cells at their edges. we have isolated 115 independent mutants of m. xanthus with insertions of transposon magellan-4 in potential a genes by screening for insertions that reduce the motility of a mutant s- parental stra ... | 2003 | 12828649 |
| retron reverse transcriptase rrtt is ubiquitous in strains of salmonella enterica serovar typhimurium. | bacterial retron reverse transcriptases are unusual enzymes which utilise the same rna molecule as a template and also as a primer for initiation of the reverse transcription. except for their relatively frequent presence in myxococcus spp., they are considered as quite rare proteins. however, in this study we proved that retron reverse transcriptase is frequently found in certain serovars of salmonella enterica. using polymerase chain reaction (pcr), in strains of serovar typhimurium, the rrtt ... | 2003 | 12829299 |
| identification of an activator protein required for the induction of frua, a gene essential for fruiting body development in myxococcus xanthus. | myxococcus xanthus exhibits social behavior and multicellular development. frua is an essential transcription factor for fruiting body development in m. xanthus. in the present study, the upstream promoter region was found to be necessary for the induction of frua expression during development. a cis-acting element required for the induction was identified and was located between nucleotides -154 and -107 with respect to the transcription initiation site. in addition, it was found that two bindi ... | 2003 | 12851461 |
| lexa-independent dna damage-mediated induction of gene expression in myxococcus xanthus. | myxococcus xanthus, a member of the proteobacteria delta-class, has two independent reca genes, reca1 and reca2, but only reca2 is dna damage-inducible. the lexa gene has been isolated from m. xanthus by pcr amplification with oligonucleotides designed after sequence identification by tblastn analysis of its genome at the cereon microbial sequence database. the m. xanthus purified lexa protein is shown to bind specifically to the consensus sequence ctrhamrybygttcags present upstream of lexa and ... | 2003 | 12864858 |
| identification of the c-signal, a contact-dependent morphogen coordinating multiple developmental responses in myxococcus xanthus. | the regulated accumulation of the contact-dependent extracellular c-signal morphogen in the bacterium myxococcus xanthus ensures the temporal and spatial coordination of multicellular morphogenesis and cellular differentiation during fruiting body formation. synthesis of the c-signal depends on the csga gene. the csga protein exists in two forms, the full-length 25-kd protein (p25), which is homologous to short-chain alcohol dehydrogenases, and a 17-kd protein (p17). the molecular nature of the ... | 2003 | 12923062 |
| membrane localization of motility, signaling, and polyketide synthetase proteins in myxococcus xanthus. | myxococcus xanthus cells coordinate cellular motility, biofilm formation, and development through the use of cell signaling pathways. in an effort to understand the mechanisms underlying these processes, the inner membrane (im) and outer membrane (om) of strain dk1622 were fractionated to examine protein localization. membranes were enriched from spheroplasts of vegetative cells and then separated into three peaks on a three-step sucrose gradient. the high-density fraction corresponded to the pu ... | 2003 | 12923079 |
| todk, a putative histidine protein kinase, regulates timing of fruiting body morphogenesis in myxococcus xanthus. | in response to starvation, myxococcus xanthus initiates a developmental program that results in the formation of spore-filled multicellular fruiting bodies. fruiting body formation depends on the temporal and spatial coordination of aggregation and sporulation. these two processes are induced by the cell surface-associated c signal, with aggregation being induced after 6 h and sporulation being induced once cells have completed the aggregation process. we report the identification of todk, a put ... | 2003 | 12949097 |
| evolution of novel cooperative swarming in the bacterium myxococcus xanthus. | cooperation among individuals is necessary for evolutionary transitions to higher levels of biological organization. in such transitions, groups of individuals at one level (such as single cells) cooperate to form selective units at a higher level (such as multicellular organisms). though the evolution of cooperation is difficult to observe directly in higher eukaryotes, microorganisms do offer such an opportunity. here we report the evolution of novel cooperative behaviour in experimental linea ... | 2003 | 12955143 |
| precipitation of barite by myxococcus xanthus: possible implications for the biogeochemical cycle of barium. | bacterial precipitation of barite (baso(4)) under laboratory conditions is reported for the first time. the bacterium myxococcus xanthus was cultivated in a solid medium with a diluted solution of barium chloride. crystallization occurred as a result of the presence of live bacteria and the bacterial metabolic activity. a phosphorous-rich amorphous phase preceded the more crystalline barite formation. these experiments may indicate the involvement of bacteria in the barium biogeochemical cycle, ... | 2003 | 12957970 |
| competitive fates of bacterial social parasites: persistence and self-induced extinction of myxococcus xanthus cheaters. | cooperative biological systems are susceptible to disruption by cheating. using the social bacterium myxococcus xanthus, we have tested the short-term competitive fates of mixed cheater and wild-type strains over multiple cycles of cooperative development. cheater/wild-type mixes underwent several cycles of starvation-induced multicellular development followed by spore germination and vegetative population growth. the population sizes of cheater and wild-type strains in each pairwise mixture wer ... | 2003 | 12965020 |
| [studies on the nutrition of various myxobacteria]. | | 1953 | 13159244 |
| [further studies on myxobacteria]. | | 1953 | 13159251 |
| lysis of human pathogenic bacteria by myxobacteria. | | 1955 | 13235825 |
| substrates for myxococcus virescens with special reference to eubacterial fractions. | | 1956 | 13319634 |
| decomposition of xylan by sporocytophaga myxococcoides. | | 1956 | 13321979 |
| the nuclear cycle of myxococcus fulvus. | | 1957 | 13406220 |
| [studies on nutrition and fruit body formation in myxobacteria]. | | 1957 | 13522162 |
| the cell wall of myxococcus xanthus. | | 1958 | 13560439 |
| lysis of myxococcus xanthus. | | 1958 | 13575754 |
| microcyst of myxococcus xanthus. chemical composition of the wall. | | 1961 | 13681547 |
| association of a steroid and a pigment with a diffusible fruiting factor in myxococcus virescens. | | 1961 | 13789858 |
| the formation and germination of microcysts in myxococcus xanthus. | | 1962 | 13888809 |
| nutritional requirements for vegetative growth of myxococcus xanthus. | dworkin, martin (indiana university medical center, indianapolis, ind.). nutritional requirements for vegetative growth of myxococcus xanthus. j. bacteriol. 84:250-257. 1962.-this investigation was part of a program to clarify the environmental regulation of fruiting-body formation in a fruiting myxobacterium. by use of a dispersed-growing strain of myxococcus xanthus, the nutritional requirements for vegetative growth have been defined. exponential growth will take place on a medium containing ... | 1962 | 13888810 |
| developmental biology of myxococcus. | mcvittie, anne (cornell university, ithaca, n.y.), frances messik, and stanley a. zahler. developmental biology of myxococcus. j. bacteriol. 84:546-551. 1962.-methods for the growth and enumeration of strain fb of myxococcus xanthus were investigated. several mutants unable to form fruiting bodies were isolated. these fell into at least two classes. members of each class acted synergistically with members of other classes to form fruiting bodies; intraclass synergism did not occur. mechanisms fo ... | 1962 | 13932286 |
| [studies on myxococcus xanthus. ii. partial lysis of pullularia pullulans and some true yeasts by an extracellular enzyme system]. | | 1963 | 13967334 |
| fine structure of myxococcus xanthus during morphogenesis. | voelz, herbert (indiana university medical center, indianapolis) and martin dworkin. fine structure of myxococcus xanthus during morphogenesis. j. bacteriol. 84:943-952. 1962.-this investigation concerns the nature of the structural changes in myxococcus xanthus during cellular morphogenesis. these changes have been investigated by means of electromicrographs of thin sections of cells taken during various stages of the life cycle. the conversion of vegetative cells to microcysts involves the for ... | 1962 | 13997609 |
| nutritional regu.ation of morphogenesis in myxococcus xanthus. | dworkin, martin (university of minnesota, minneapolis). nutritional regulation of morphogenesis in myxococcus xanthus. j. bacteriol. 86:67-72. 1963.-fruiting-body formation by myxococcus xanthus can be induced by omitting phenylalanine and tryptophan from the chemically defined growth medium. this effect was specific for these two amino acids and was not attributable to a nonspecific lowering of the growth rate. a complex pool of amino acids is present in vegetative cells of m. xanthus. nutritio ... | 1963 | 14051824 |
| control of growth and morphogenesis in some myxococcus species. | | 1963 | 14098465 |
| electron transport system in vegetative cells and microcysts of myxococcus xanthus. | dworkin, martin (university of minnesota, minneapolis), and donald j. niederpruem. electron transport system in vegetative cells and microcysts of myxococcus xanthus. j. bacteriol. 87:316-322. 1964.-respiration by intact cells of the fruiting myxobacterium myxococcus xanthus is cyanide-sensitive and can be demonstrated in the vegetative cells but not in the microcysts. cell-free particles from both vegetative cells and microcysts have cyanide-sensitive reduced nicotinamide adenine dinucleotide ( ... | 1964 | 14151050 |
| a system for studying microbial morphogenesis: rapid formation of microcysts in myxococcus xanthus. | a method has been found for inducing the rapid, quantitative, and relatively synchronous conversion of vegetative rods of a fruiting myxobacterium to microcysts. the conversion is induced by the addition of 0.5m glycerol to a dispersed, growing, liquid culture of myxococcus xanthus. the vegetative rods are converted to microcysts in about 120 minutes. | 1964 | 14185314 |
| fruiting body populations of myxococcus fulvus (myxobacterales). | | 1965 | 14324921 |
| formation and structure of mesosomes in myxococcus xanthus. | | 1965 | 14347924 |
| [myxobacillus accepted as nitrifying bacteria]. | | 1955 | 14383367 |
| [studies on cellulose catabolism by myxobacteria]. | | 1959 | 14412492 |
| antibiotic activity of myxobacteria in relation to their bacteriolytic capacity. | norén, börge (university of wisconsin, madison) and kenneth b. raper. antibiotic activity of myxobacteria in relation to their bacteriolytic capacity. j. bacteriol. 84:157-162. 1962-myxococcus virescens, m. fulvus, m. stipitatus, m. lacteus, chondrococcus blasticus, and chondromyces crocatus were tested for antibacterial activity, and all were found to secrete products that inhibited the growth of gram-positive eubacteria. the amount of inhibition varied with the myxobacterium employed and with ... | 1962 | 14480333 |
| [isolation and purification of aerobic cellulolytic soil bacteria. ii. isolation and description of a new arthrobacter species associated with sporocytophaga myxococcoides]. | | 1961 | 14492583 |
| interplay of chemotaxis and chemokinesis mechanisms in bacterial dynamics. | motivated by observations of the dynamics of myxococcus xanthus, we present a self-interacting random walk model that describes the competition between chemokinesis and chemotaxis. cells are constrained to move in one dimension, but release a chemical chemoattractant at a steady state. the bacteria sense the chemical that they produce. the probability of direction reversals is modeled as a function of both the absolute level of chemoattractant sensed directly under each cell as well as the gradi ... | 2003 | 14525024 |
| global mutational analysis of ntrc-like activators in myxococcus xanthus: identifying activator mutants defective for motility and fruiting body development. | the multicellular developmental cycle of myxococcus xanthus requires large-scale changes in gene transcription, and recent findings indicate that ntrc-like activators play a prominent role in regulating these changes. in this study, we made insertions in 28 uncharacterized ntrc-like activator (nla) genes and found that eight of these insertions cause developmental defects. hence, these results are consistent with the idea that m. xanthus uses a series of different ntrc-like activators during fru ... | 2003 | 14526020 |
| characterization of the integrase gene and attachment site for the myxococcus xanthus bacteriophage mx9. | bacteriophage mx9 is a temperate phage that infects myxococcus xanthus. it lysogenizes the bacteria by integrating into the bacterial chromosome by site-specific recombination at one of two sites, attb1 or attb2. integration at attb1 results in deletion of dna between the two attb sites. the attb2 site lies within the 5' region of the m. xanthus trna(gly) gene. mx9 integration requires a single protein, int. analysis of integration revealed that the phage attachment site (attp) is contained in t ... | 2003 | 14563867 |
| isolation and characterization of new epothilone analogues from recombinant myxococcus xanthus fermentations. | nine new epothilone analogues (6-8, 10, 11a, 11b, 12, 13, and 15) were isolated from fermentations of myxococcus xanthus strains engineered with modified polyketide synthase genes. the epothilone structures were elucidated primarily through interpretation of 1d and 2d nmr data. 4-desmethyl-10,11-didehydroepothilone d (6) displayed activity against several tumor cell lines, including a multi-drug-resistant cell line. | 2003 | 14575429 |
| cell behavior and cell-cell communication during fruiting body morphogenesis in myxococcus xanthus. | formation of spatial patterns of cells from a mass of initially identical cells is a recurring theme in developmental biology. the dynamics that direct pattern formation in biological systems often involve morphogenetic cell movements. an example is fruiting body formation in the gliding bacterium myxococcus xanthus in which an unstructured population of identical cells rearranges into an asymmetric, stable pattern of multicellular fruiting bodies in response to starvation. fruiting body formati ... | 2003 | 14607429 |
| production and characterization of the milk-clotting protease of myxococcus xanthus strain 422. | the cheese industry is seeking novel sources of enzymes for cheese production. microbial rennets have several advantages over animal rennets. (1) they are easy to generate and purify and do not rely on the availability of animal material. (2) the production of microbial clotting enzymes may be improved by biotechnological techniques. in this work, the biochemical characterization of a novel milk-clotting extracellular enzyme from myxococcus xanthus strain 422 and a preliminary evaluation of its ... | 2003 | 14634834 |
| myxobacteria: proficient producers of novel natural products with various biological activities--past and future biotechnological aspects with the focus on the genus sorangium. | myxobacteria are gram-negative bacteria which are most noted for their ability to form fruiting bodies upon starvation. within the last two decades, they increasingly gained attention as producers of natural products with biological activity. here, recent and future biotechnological research on certain key myxobacteria and on their ability to produce natural products is reviewed with the focus on the production of myxovirescin, soraphen and epothilone. aspects of product improvement and yield as ... | 2003 | 14651865 |
| multicellular development and gliding motility in myxococcus xanthus. | a great deal of progress has been made in the studies of fruiting body development and social gliding in myxocococcus xanthus in the past few years. this includes identification of the bone fide c-signal and a receptor for type iv pili, and development of a model for the mechanism of adventurous gliding motility. it is anticipated that the next few years will see even more progress as the complete genome sequence is available and genomic and proteomic tools are applied to the study of m. xanthus ... | 2003 | 14662352 |
| mutational analysis of the myxococcus xanthus omega4400 promoter region provides insight into developmental gene regulation by c signaling. | myxococcus xanthus utilizes extracellular signals during development to coordinate cell movement, differentiation, and changes in gene expression. one of these signals, the c signal, regulates the expression of many genes, including omega4400, a gene identified by an insertion of tn5 lac into the chromosome. expression of tn5 lac omega4400 is reduced in csga mutant cells, which fail to perform c signaling, and the promoter region has several sequences similar to sequences found in the regulatory ... | 2004 | 14729691 |
| evolution of cooperation: two for one? | how can cooperation thrive in a selfish world? recent evolution experiments show how bacteria themselves can generate conditions that make cooperation a winning strategy. at least in the short term. | 2004 | 14738754 |
| dynamics of fruiting body morphogenesis. | myxobacteria build their species-specific fruiting bodies by cell movement and then differentiate spores in specific places within that multicellular structure. new steps in the developmental aggregation of myxococcus xanthus were discovered through a frame-by-frame analysis of a motion picture. the formation and fate of 18 aggregates were captured in the time-lapse movie. still photographs of 600 other aggregates were also analyzed. m. xanthus has two engines that propel the gliding of its rod- ... | 2004 | 14761986 |
| myxococcus xanthus chemotaxis homologs difd and difg negatively regulate fibril polysaccharide production. | the extracellular matrix fibrils of myxococcus xanthus are essential for the social lifestyle of this unusual bacterium. these fibrils form networks linking or encasing cells and are tightly correlated with cellular cohesion, development, and social (s) gliding motility. previous studies identified a set of bacterial chemotaxis homologs encoded by the dif locus. it was determined that difa, difc, and dife, encoding respective homologs of a methyl-accepting chemotaxis protein, chew, and chea, are ... | 2004 | 14761994 |
| rippling of myxobacteria. | myxobacteria colonies during their aggregation phase propagate complex waves over their surface. these waves are fundamentally different from the analogous phenomenon in diffusion-reaction systems or in populations of dictyostelium discoideum where colliding waves annhilate. myxobacterial waves appear to pass through one another, analogous to solitons. moreover, individual bacteria oscillate back and forth, exhibiting no net mass transfer. a mathematical model can explain virtually all of the ex ... | 2004 | 14766104 |
| rppa, a transducer homologue, and mmra, a multidrug transporter homologue, are involved in the biogenesis and/or assembly of polysaccharide in myxococcus xanthus. | myxococcus xanthus cells move by gliding, and form multicellular fruiting bodies under conditions of starvation. the authors cloned a gene, designated rppa (for receptor for polysaccharide production), which encodes a methyl-accepting protein homologous to the chemotaxis transducers in eubacteria. the rppa gene was co-transcribed with mmra, a gene homologous to various multidrug transporter genes. the rppa or mmra single mutants showed almost identical phenotypes to the wild-type strain; however ... | 2004 | 14993312 |
| strategies of microbial cheater control. | the potential benefits of cooperation in microorganisms can be undermined by genetic conflict within social groups, which can take the form of 'cheating'. for cooperation to succeed as an evolutionary strategy, the negative effects of such conflict must somehow be either prevented or mitigated. to generate an interpretive framework for future research in microbial behavioural ecology, here we outline a wide range of hypothetical mechanisms by which cheaters might be constrained. | 2004 | 15036323 |
| coupling cell movement to multicellular development in myxobacteria. | the myxobacteria are gram-negative organisms that are capable of multicellular, social behaviour. in the presence of nutrients, swarms of myxobacteria feed cooperatively by sharing extracellular digestive enzymes, and can prey on other bacteria. when the food supply runs low, they initiate a complex developmental programme that culminates in the production of a fruiting body. myxobacteria move by gliding and have two, polarly positioned engines to control their motility. the two engines undergo ... | 2003 | 15040179 |
| [effect of uv-radiation and drying on bacterium diversity in soil]. | it has been shown that after dna-injuring factors (uv irradiation or drying) action on soil one could observe the decrease of the total quantity of bacteria and the number of species, i.e., the decrease of microbe diversity. at the same time not numerous species were found in soils after their action. thus the drying or uv-irradiation makes it possible to estimate more completely the microbe diversity in soils as well as to find resistant bacteria. it has been established that the strain methylo ... | 2004 | 15104058 |
| operator design and mechanism for cara repressor-mediated down-regulation of the photoinducible carb operon in myxococcus xanthus. | the carb operon encodes all except one of the enzymes involved in light-induced carotenogenesis in myxococcus xanthus. expression of its promoter (p(b)) is repressed in the dark by sequence-specific dna binding of cara to a palindrome (pi) located between positions -47 and -64 relative to the transcription start site. this promotes subsequent binding of cara to additional sites that remain to be defined. cars, produced in the light, interacts physically with cara, abrogates cara-dna binding, and ... | 2004 | 15123730 |
| nsd, a locus that affects the myxococcus xanthus cellular response to nutrient concentration. | expression of the previously reported tn5lac omega4469 insertion in myxococcus xanthus cells is regulated by the starvation response. interested in learning more about the starvation response, we cloned and sequenced the region containing the insertion. our analysis shows that the gene fusion is located in an open reading frame that we have designated nsd (nutrient sensing/utilizing defective) and that its expression is driven by a sigma70-like promoter. sequence analysis of the nsd gene product ... | 2004 | 15150233 |
| analysis of frue, a novel developmental gene of myxococcus xanthus. | myxococcus xanthus is a gram-negative soil bacterium that undergoes multicellular development upon nutrient starvation. in the present study, a tnv insertion developmental mutation, omega773, of m. xanthus was analyzed. the tnv omega773 insertion was found to be located within a novel developmental gene, frue. the frue protein is composed of 140 amino acid residues and bears an n-terminal signal peptide. the amino acid sequence of frue shared no significant similarity with any other known protei ... | 2003 | 15153769 |
| the n terminus of myxococcus xanthus cara repressor is an autonomously folding domain that mediates physical and functional interactions with both operator dna and antirepressor protein. | expression of the myxococcus xanthus carb operon, which encodes the majority of the enzymes involved in light-induced carotenogenesis, is down-regulated in the dark by the cara repressor binding to its bipartite operator. cars, produced on illumination, relieves repression of carb by physically interacting with cara to dis-mantle cara-dna complexes. here, we demonstrate that the n- and c-terminal portions of cara are organized as distinct structural and functional domains. specifically, we show ... | 2004 | 15163666 |
| biosynthesis of volatiles by the myxobacterium myxococcus xanthus. | the volatiles emitted from cell cultures of myxobacterium myxococcus xanthus were collected by use of a closed-loop stripping apparatus (clsa) and analyzed by gc-ms. two new natural products, (s)-9-methyldecan-3-ol ((s)-1) and 9-methyldecan-3-one (2), were identified and synthesized, together with other aliphatic ketones and alcohols, and terpenes. biosynthesis of the two main components (s)-1 and 2 was examined in feeding experiments carried out with the wild-type strain dk1622 and two mutant s ... | 2004 | 15174160 |
| mutational analysis of the myxococcus xanthus omicron4499 promoter region reveals shared and unique properties in comparison with other c-signal-dependent promoters. | the bacterium myxococcus xanthus undergoes multicellular development during times of nutritional stress and uses extracellular signals to coordinate cell behavior. c-signal affects gene expression late in development, including that of omega4499, an operon identified by insertion of tn5 lac into the m. xanthus chromosome. the omega4499 promoter region has several sequences in common with those found previously to be important for expression of other c-signal-dependent promoters. to determine if ... | 2004 | 15175290 |
| the che4 pathway of myxococcus xanthus regulates type iv pilus-mediated motility. | myxococcus xanthus co-ordinates cell movement during its complex life cycle using multiple chemotaxis-like signal transduction pathways. these pathways regulate both type iv pilus-mediated social (s) motility and adventurous (a) motility. during a search for new chemoreceptors, we identified the che4 operon, which encodes homologues to a mcp (methyl-accepting chemotaxis protein), two chews, a hybrid chea-chey, a response regulator and a cher. deletion of the che4 operon did not cause swarming or ... | 2004 | 15186426 |
| sigma54 enhancer binding proteins and myxococcus xanthus fruiting body development. | a search of the m1genome sequence, which includes 97% of the myxococcus xanthus genes, identified 53 sequence homologs of sigma54-dependent enhancer binding proteins (ebps). a dna microarray was constructed from the m1genome that includes those homologs and 318 other m. xanthus genes for comparison. to screen the developmental program with this array, an rna extract from growing cells was compared with one prepared from developing cells at 12 h. previous reporter studies had shown that m. xanthu ... | 2004 | 15205438 |
| myxococcus xanthus biomass as biosorbent for lead. | this paper deals with lead biosorption by myxococcus xanthus biomass in which dry biomass, accumulating up to 1.28 mmol of lead g(-1), is demonstrated to be a more efficient biosorbent than wet biomass. dry biomass biosorption was found to be very rapid, reaching equilibrium after 5-10 min. culture age, the initial lead concentration and ph affected this process, but temperature did not. furthermore, by using sodium citrate as a desorbent agent, 92.17% of the biosorbed lead could be recovered. i ... | 1998 | 15244058 |
| comparative biochemical analysis of three bacterial prolyl endopeptidases: implications for coeliac sprue. | prolyl endopeptidases have potential for treating coeliac sprue, a disease of the intestine caused by proteolytically resistant peptides from proline-rich prolamins of wheat, barley and rye. we compared the properties of three similar bacterial prolyl endopeptidases, including the known enzymes from flavobacterium meningosepticum (fm) and sphingomonas capsulate (sc) and a novel enzyme from myxococcus xanthus (mx). these enzymes were interrogated with reference chromogenic substrates, as well as ... | 2004 | 15245330 |
| htha, a putative dna-binding protein, and hthb are important for fruiting body morphogenesis in myxococcus xanthus. | in response to starvation, myxococcus xanthus initiates a developmental programme that results in the formation of spore-filled multicellular fruiting bodies. fruiting body formation depends on the temporal and spatial coordination of aggregation and sporulation and involves temporally and spatially coordinated changes in gene expression. this paper reports the identification of two genes, htha and hthb, that are important for fruiting body formation. htha and hthb are co-transcribed, and transc ... | 2004 | 15256560 |
| mutational analysis of the frua promoter region demonstrates that c-box and 5-base-pair elements are important for expression of an essential developmental gene of myxococcus xanthus. | myxococcus xanthus uses extracellular signals during development to regulate gene expression. c-signaling regulates the expression of many genes induced after 6 h into development. frua is a protein that is necessary for cells to respond to c-signaling, but expression of the frua gene does not depend on c-signaling. yet the frua promoter region has a c box and a 5-bp element, similar to the promoter regions of several c-signal-dependent genes, where these sequences are crucial. here, we show tha ... | 2004 | 15317804 |
| a myxococcus xanthus rppa-mmra double mutant exhibits reduced uptake of amino acids and tolerance of some antimicrobials. | myxococcus xanthus rppa and mmra are homologous to methyl-accepting chemotaxis proteins (mcps) and to multidrug transporters, respectively. we reported previously that rppa-mmra double mutant exhibited reduced colony expansion, agglutination, and polysaccharide levels. we have demonstrated here that the rppa-mmra mutant also exhibited reduced amino acid uptake. furthermore, the double mutant appeared to be more susceptible to some antimicrobial agents, such as streptomycin, ethidium bromide and ... | 2004 | 15336415 |
| the high-mobility group a-type protein card of the bacterium myxococcus xanthus as a transcription factor for several distinct vegetative genes. | card is the only reported prokaryotic protein showing structural and functional features typical of eukaryotic high-mobility group a transcription factors. in prokaryotes, proteins similar to card appear to be confined primarily to myxobacteria. in myxococcus xanthus, card has been previously shown to act as a positive element in two different regulatory networks: one for light-induced synthesis of carotenoids and the other for starvation-induced fruiting body formation. we have now tested the e ... | 2004 | 15342500 |
| aglz is a filament-forming coiled-coil protein required for adventurous gliding motility of myxococcus xanthus. | the aglz gene of myxococcus xanthus was identified from a yeast two-hybrid assay in which mgla was used as bait. mgla is a 22-kda cytoplasmic gtpase required for both adventurous and social gliding motility and sporulation. genetic studies showed that aglz is part of the a motility system, because disruption or deletion of aglz abolished movement of isolated cells and aglz sglk double mutants were nonmotile. the aglz gene encodes a 153-kda protein that interacts with purified mgla in vitro. the ... | 2004 | 15342587 |
| analysis of the frz signal transduction system of myxococcus xanthus shows the importance of the conserved c-terminal region of the cytoplasmic chemoreceptor frzcd in sensing signals. | the frz chemosensory system controls directed motility in myxococcus xanthus by regulating cellular reversal frequency. m. xanthus requires the frz system for vegetative swarming on rich media and for cellular aggregation during fruiting body formation on starvation media. the frz signal transduction pathway is formed by proteins that share homology with chemotaxis proteins from enteric bacteria, which are encoded in the frza-f putative operon and the divergently transcribed frzz gene. frzcd, th ... | 2004 | 15387825 |
| cloning and expression of clt genes encoding milk-clotting proteases from myxococcus xanthus 422. | the screening of a gene library of the milk-clotting strain myxococcus xanthus 422 constructed in escherichia coli allowed the description of eight positive clones containing 26 open reading frames. only three of them (clta, cltb, and cltc) encoded proteins that exhibited intracellular milk-clotting ability in e. coli, saccharomyces cerevisiae, and pichia pastoris expression systems. | 2004 | 15466588 |
| signaling in myxobacteria. | myxobacteria use soluble and cell-contact signals during their starvation-induced formation of fruiting bodies. these signals coordinate developmental gene expression with the cell movements that build fruiting bodies. early in development, the quorum-sensing a-signal in myxococcus xanthus helps to assess starvation and induce the first stage of aggregation. later, the morphogenetic c-signal helps to pattern cell movement and shape the fruiting body. c-signal is a 17-kda cell surface protein tha ... | 2004 | 15487930 |
| structure and function of the shufflon in plasmid r64. | conservative site-specific recombination plays key roles in creating biological diversity in prokaryotes. most site-specific inversion systems consist of two recombination sites and a recombinase gene. in contrast, the shufflon multiple inversion system of plasmid r64 consists of seven sfx recombination sites, which separate four invertible dna segments, and the rci gene encoding a site-specific recombinase of the integrase family. the rci product mediates recombination between any two inverted ... | 2004 | 15493334 |
| a biochemical oscillator explains several aspects of myxococcus xanthus behavior during development. | during development, myxococcus xanthus cells produce a series of spatial patterns by coordinating their motion through a contact-dependent signal, the c-signal. c-signaling modulates the frequency at which cells reverse their gliding direction. it does this by interacting with the frz system (a homolog of the escherichia coli chemosensory system) via a cascade of covalent modifications. here we show that introducing a negative feedback into this cascade results in oscillatory behavior of the sig ... | 2004 | 15496464 |
| reconstruction of the evolutionary history of the lexa-binding sequence. | in recent years, the recognition sequence of the sos repressor lexa protein has been identified for several bacterial clades, such as the gram-positive, green non-sulfur bacteria and cyanobacteria phyla, or the 'alphaproteobacteria', 'deltaproteobacteria' and 'gammaproteobacteria' classes. nevertheless, the evolutionary relationship among these sequences and the proteins that recognize them has not been analysed. fibrobacter succinogenes is an anaerobic gram-negative bacterium that branched from ... | 2004 | 15528664 |
| genetic dissection of the light-inducible carqrs promoter region of myxococcus xanthus. | in myxococcus xanthus photoprotective carotenoids are produced in response to illumination due to regulated expression of carotenoid biosynthesis genes at two loci. induction of the carotenogenesis regulon is dependent on expression of the carqrs operon. the first gene product of the operon, carq, is a sigma factor belonging to the ecf family and is responsible for light-dependent initiation of transcription at the carqrs promoter. we defined the minimal carqrs promoter as a 145-bp fragment of d ... | 2004 | 15547254 |
| cell polarity, intercellular signalling and morphogenetic cell movements in myxococcus xanthus. | in myxococcus xanthus morphogenetic cell movements constitute the basis for the formation of spreading vegetative colonies and fruiting bodies in starving cells. m. xanthus cells move by gliding and gliding motility depends on two polarly localized engines, type iv pili pull cells forward, and slime extruding nozzle-like structures appear to push cells forward. the motility behaviour of cells provides evidence that the two engines are localized to opposite poles and that they undergo polarity sw ... | 2004 | 15556030 |
| characterization of a myxococcus xanthus mutant that is defective for adventurous motility and social motility. | myxococcus xanthus is a gliding bacterium that possesses two motility systems, the adventurous (a-motility) and social (s-motility) systems. a-motility is used for individual cell gliding, while s-motility is used for gliding in multicellular groups. video microscopy studies showed that nla24 cells are non-motile on agar surfaces, suggesting that the nla24 gene product is absolutely required for both a-motility and s-motility under these assay conditions. s-motility requires functional type iv p ... | 2004 | 15583161 |
| exopolysaccharide biosynthesis genes required for social motility in myxococcus xanthus. | social (s)-motility in myxococcus xanthus is a flagellum-independent gliding motility system that allows bacteria to move in groups on solid surfaces. s-motility has been shown to require type iv pili (tfp), exopolysaccharide (eps; a component of fibrils) and lipopolysaccharide (lps). previously, information concerning eps biogenesis in m. xanthus was lacking. in this study, we screened 5000 randomly mutagenized colonies for defects in s-motility and eps and identified two genetic regions essent ... | 2005 | 15612929 |
| biosynthesis of iso-fatty acids in myxobacteria: iso-even fatty acids are derived by alpha-oxidation from iso-odd fatty acids. | the biosynthesis of iso-fatty acids was investigated in the myxobacteria myxococcus xanthus and stigmatella aurantiaca by feeding labeled precursors of these fatty acids and by conducting detailed analysis of the fatty acid profiles and fatty acid ms and nmr spectra. these experiments revealed that in s. aurantiaca all iso-even fatty acids are formed via alpha-oxidation of iso-odd fatty acids and not by using valine-derived isobutyryl-coa. | 2005 | 15643871 |
| enhancer-binding proteins with a forkhead-associated domain and the sigma54 regulon in myxococcus xanthus fruiting body development. | in response to starvation, myxococcus xanthus initiates a developmental program that results in the formation of spore-filled, multicellular fruiting bodies. many developmentally regulated genes in m. xanthus are transcribed from sigma(54) promoters, and these genes require enhancer-binding proteins. here we report the finding of an unusual group of 12 genes encoding sigma(54)-dependent enhancer-binding proteins containing a forkhead-associated (fha) domain as their n-terminal sensory domain. fh ... | 2005 | 15668379 |
| analysis of type iv pilus and its associated motility in myxococcus xanthus using an antibody reactive with native pilin and pili. | myxococcus xanthus possesses a social gliding motility that requires type iv pili (tfp). according to the current model, m. xanthus pili attach to an external substrate and retract, pulling the cell body forward along their long axis. by analogy with the situation in other bacteria employing tfp-dependent motility, m. xanthus pili have been assumed to be composed of pilin (pila) subunits, but this has not previously been confirmed. the first 28 amino acids of the m. xanthus pila protein share ex ... | 2005 | 15699186 |
| eukaryotic-like signaling and gene regulation in a prokaryote that undergoes multicellular development. | | 2005 | 15710872 |
| characterization of developmental autolysis in myxobacterial fruiting body morphogenesis with profiling of amino acids using capillary electrophoresis method. | capillary electrophoresis equipped with laser-induced fluorescence (ce-lif), combining with micro-culture technique was employed to determine extracellular amino acids in single myxobacterial fruiting body morphogenesis. the result showed that in the early aggregation stage, there was a remarkable increase of extracellular amino acids, which was produced by developmentally induced autolysis. the amino acids were then consumed by the vegetative cells in aggregation stage. in the following develop ... | 2005 | 15711868 |
| divergent regulatory pathways control a and s motility in myxococcus xanthus through frze, a chea-chey fusion protein. | myxococcus xanthus moves on solid surfaces by using two gliding motility systems, a motility for individual-cell movement and s motility for coordinated group movements. the frz genes encode chemotaxis homologues that control the cellular reversal frequency of both motility systems. one of the components of the core frz signal transduction pathway, frze, is homologous to both chea and chey from the enteric bacteria and is therefore a novel chea-chey fusion protein. in this study, we investigated ... | 2005 | 15716443 |
| grouping myxococci (corallococcus) strains by matrix-assisted laser desorption ionization time-of-flight (maldi tof) mass spectrometry: comparison with gene sequence phylogenies. | nine corallococcus isolates and three type strains of corallococcus species were characterized by intact cell mass spectrometry using matrix assisted laser desorption ionization time-of-flight (maldi-tof) mass spectrometry. the resulting phenetic clustering was compared to the phylogenetic grouping based upon sequences of two housekeeping genes. the three dendrograms of relatedness resembled each other in that the isolates were highly similar to the type strains of corallococcus exiguus and cora ... | 2005 | 15717228 |
| a myxococcus xanthus cbpb containing two camp-binding domains is involved in temperature and osmotic tolerances. | our previous data indicated that a myxococcus xanthus sensor-type adenylyl cyclase (cyaa) functions in signal transduction during osmotic stress. however, the camp-mediated signal transduction pathway in this bacterium was unknown. here, we isolated a clone from a m. xanthus genomic dna library using oligonucleotide probes designed based on the conserved camp-binding domains of the camp-dependent protein kinase (pka) regulatory subunits. the clone contained two open-reading frames (orfs), cbpa a ... | 2005 | 15727824 |
| structural and mechanistic analysis of two prolyl endopeptidases: role of interdomain dynamics in catalysis and specificity. | prolyl endopeptidases (peps) are a unique class of serine proteases with considerable therapeutic potential for the treatment of celiac sprue. the crystal structures of two didomain peps have been solved in alternative configurations, thereby providing insights into the mode of action of these enzymes. the structure of the sphingomonas capsulata pep, solved and refined to 1.8-a resolution, revealed an open configuration of the active site. in contrast, the inhibitor-bound pep from myxococcus xan ... | 2005 | 15738423 |
| regulating pilin expression reveals a threshold for s motility in myxococcus xanthus. | an isopropyl-beta-d-thiogalactopyranoside (iptg)-inducible promoter was constructed in myxococcus xanthus. the single-copy pila gene encodes pilin, the monomer unit of m. xanthus type iv pili. to vary the level of pila expression, we cloned its promoter in front of the lac operator, and a plasmid containing the construct was inserted into the chromosome of a deltapila strain. induction of pilin expression increased smoothly as the dose of iptg added to the culture was increased. iptg-induced pil ... | 2005 | 15743959 |
| demonstration of interactions among myxococcus xanthus dif chemotaxis-like proteins by the yeast two-hybrid system. | the myxococcus xanthus dif locus encodes several bacterial chemotaxis homologues that are crucial for fibril exopolysaccharide (eps) production, social gliding motility, and fruiting body development. in primary sequence, difa is homologous to methyl-accepting chemotaxis protein, difc to chew, difd to chey, dife to chea, and difg to chec. in this study, the interactions among the dif chemotaxis-like proteins were investigated using the yeast two-hybrid (y2h) system. difc was found to interact wi ... | 2005 | 15770502 |
| an individual based model of rippling movement in a myxobacteria population. | migrating cells of myxococcus xanthus (mx) in the early stages of starvation-induced development exhibit elaborate patterns of propagating waves. these so-called rippling patterns are formed by two sets of waves travelling in opposite directions. it has been experimentally shown that formation of these waves is mediated by cell-cell contact signalling (c-signalling). here, we develop an individual-based model to study the formation of rippling patterns in mx populations. following the work of ig ... | 2005 | 15784269 |
| bioinformatics, genomics and evolution of non-flagellar type-iii secretion systems: a darwinian perspective. | we review the biology of non-flagellar type-iii secretion systems from a darwinian perspective, highlighting the themes of evolution, conservation, variation and decay. the presence of these systems in environmental organisms such as myxococcus, desulfovibrio and verrucomicrobium hints at roles beyond virulence. we review newly discovered sequence homologies (e.g., yopn/tyea and sepl). we discuss synapomorphies that might be useful in formulating a taxonomy of type-iii secretion. the problem of ... | 2005 | 15808742 |
| nanoscale visualization and characterization of myxococcus xanthus cells with atomic force microscopy. | multicellular microbial communities are the predominant form of existence for microorganisms in nature. as one of the most primitive social organisms, myxococcus xanthus has been an ideal model bacterium for studying intercellular interaction and multicellular organization. through previous genetic and em studies, various extracellular appendages and matrix components have been found to be involved in the social behavior of m. xanthus, but none of them was directly visualized and analyzed under ... | 2005 | 15840722 |
| an adenylyl cyclase, cyab, acts as an osmosensor in myxococcus xanthus. | we have previously reported that a receptor-type adenylyl cyclase (cyaa) of myxococcus xanthus undergoes an osmosensor mainly during spore germination (y. kimura et al., j. bacteriol. 184:3578-3585, 2002). in the present study, we cloned another receptor-type adenylyl cyclase gene (cyab) and characterized the function of the cyab-encoded protein. disruption of cyab generates a mutant that showed growth retardation at high ionic (nacl) or high nonionic (sucrose) osmolarity. when vegetative cells ... | 2005 | 15866951 |
| analysing protein-protein interactions of the myxococcus xanthus dif signalling pathway using the yeast two-hybrid system. | the dif operon is essential for fruiting body formation, fibril (exopolysaccharide) production and social motility of myxococcus xanthus. the dif locus contains a gene cluster homologous to chemotaxis genes such as mcp (difa), chew (difc), chey (difd), chea (dife) and chec (diff), as well as an unknown orf called difb. this study used yeast two-hybrid analysis to investigate possible interactions between dif proteins, and determined that difa, c, d and e interact in a similar fashion to chemotax ... | 2005 | 15870463 |