Publications

rescue of social motility lost during evolution of myxococcus xanthus in an asocial environment.	replicate populations of the social bacterium myxococcus xanthus underwent extensive evolutionary adaptation to an asocial selective environment (liquid batch culture). all 12 populations showed partial or complete loss of their social (s) motility function after 1,000 generations of evolution. mutations in the pil gene cluster (responsible for type iv pilus biogenesis and function) were found to be at least partially responsible for the loss of s motility in the majority of evolved lines. resto ...	2002	11976301
how myxobacteria glide.	many microorganisms, including myxobacteria, cyanobacteria, and flexibacteria, move by gliding. although gliding always describes a slow surface-associated translocation in the direction of the cell's long axis, it can result from two very different propulsion mechanisms: social (s) motility and adventurous (a) motility. the force for s motility is generated by retraction of type 4 pili. a motility may be associated with the extrusion of slime, but evidence has been lacking, and how force might ...	2002	11882287
role for vitamin b(12) in light induction of gene expression in the bacterium myxococcus xanthus.	a light-inducible promoter (p(b)) drives the carb operon (carotenoid genes) of the bacterium myxococcus xanthus. a gene encoding a regulator of carotenoid biosynthesis was identified by studying mutant strains carrying a transcriptional fusion to p(b) and deletions in three candidate genes. our results prove that the identified gene, named cara, codes for a repressor of the p(b) promoter in the dark. they also show that the cara gene product does not participate in the light activation of two ot ...	2002	11914353
mlpb, a gene encoding a new lipoprotein in myxococcus xanthus.	to search for and study the genes involved in the regulation of phosphate in the soil developmental bacterium myxococcus xanthus.	2002	11849337
the devt protein stimulates synthesis of frua, a signal transduction protein required for fruiting body morphogenesis in myxococcus xanthus.	fruiting body formation in myxococcus xanthus involves three morphologic stages---rippling, aggregation, and sporulation---all of which are induced by the cell surface-associated c-signal. we analyzed the function of the devt protein, a novel component in the c-signal response pathway. a mutant carrying an in-frame deletion in the devt gene displays delayed aggregation and a cell autonomous sporulation defect, whereas it remains rippling proficient. to further define the function of devt, the me ...	2002	11872704
classification of the caspase-hemoglobinase fold: detection of new families and implications for the origin of the eukaryotic separins.	a comprehensive sequence and structural comparative analysis of the caspase-hemoglobinase protein fold resulted in the delineation of the minimal structural core of the protease domain and the identification of numerous, previously undetected members, including a new protease family typified by the hetf protein from the cyanobacterium nostoc. the first bacterial homologs of legumains and hemoglobinases were also identified. most proteins containing this fold are known or predicted to be active p ...	2002	11835511
bypass of a- and b-signaling requirements for myxococcus xanthus development by mutations in spdr.	mutations in spdr, previously reported to bypass the developmental requirement for b-signaling in myxococcus xanthus, also bypass the requirement for a-signaling but not c-, d-, or e-signaling. mutations in spdr restored nearly wild-type levels of sporulation to representative a-signal-deficient mutants carrying asga476, asgb480, and asgc767 and improved the quality of fruiting body formation in the asgb480 mutant. the defect in a-factor production by the asgb480 mutant was not restored in the s ...	2002	11844778
act operon control of developmental gene expression in myxococcus xanthus.	cell-bound c-signal guides the building of a fruiting body and triggers the differentiation of myxospores. earlier work has shown that transcription of the csga gene, which encodes the c-signal, is directed by four genes of the act operon. to see how expression of the genes encoding components of the aggregation and sporulation processes depends on c-signaling, mutants with loss-of-function mutations in each of the act genes were investigated. these mutations were found to have no effect on gene ...	2002	11807078
activation of 6-phosphofructokinase via phosphorylation by pkn4, a protein ser/thr kinase of myxococcus xanthus.	myxococcus xanthus is a gram-negative bacterium that exhibits a communal lifestyle during vegetative growth and multicellular development, forming fruiting bodies filled with spores. it contains at least 13 eukaryotic-like protein ser/thr kinases (pstks from pkn1 to pkn13). in the present report, we demonstrate that pkn4, the gene located 18 bp downstream of the gene for 6-phosphofructokinase (pfk), is a pstk for m. xanthus pfk (mx-pfk), the key regulatory enzyme in glycolysis. both pkn4 and mx- ...	2002	12453221
mgla, a small gtpase, interacts with a tyrosine kinase to control type iv pili-mediated motility and development of myxococcus xanthus.	the mgla gene encodes a 22 kda gtpase that is critical for single-cell (a) gliding, type iv pili-mediated (s) gliding and development of myxococcus xanthus. to identify components that interact with mgla to control these processes, second-site mutations that restore movement to non-motile mgla mutants were sought. an allele-specific extragenic suppressor of mgla8, named mas815 (mgla8 suppressor 15), was obtained. mas815 does not bypass the requirement for mgla, yet it restores type iv pili-media ...	2002	12453225
analysis of dofa, a frua-dependent developmental gene, and its homologue, dofb, in myxococcus xanthus.	the developmentally regulated gene dofa, identified from pulse-labeling experiments by two-dimensional gel electrophoresis, and its homologue, dofb, were cloned and characterized in myxococcus xanthus. deletion of dofa and dofb did not affect the vegetative growth and development of m. xanthus. dofa was specifically expressed during development, while dofb expression was observed during vegetative growth and development. the dofa-lacz fusion was introduced into a frua mutant and a, b, c, d, and ...	2002	12446630
experimental social evolution with myxococcus xanthus.	genetically-based social behaviors are subject to evolutionary change in response to natural selection. numerous microbial systems provide not only the opportunity to understand the genetic mechanisms underlying specific social interactions, but also to observe evolutionary changes in sociality over short time periods. here we summarize experiments in which behaviors of the social bacterium myxococcus xanthus changed extensively during evolutionary adaptation to two relatively asocial laboratory ...	2002	12448714
development of a laser-induced cell lysis system.	a novel cell lysis system was developed that is based on laser-induced disruption of bacterial and yeast cells. it will find application as a rapid, efficient and clean sample preparation step in bioanalytical detection systems. using e. coli as our model analyte, we optimized cell lysis with respect to optimal laser wavelength, lowest energy input requirements, rna release from the cells, and potential protein damage. the optimized system was finally applied to the lysis of four additional micr ...	2002	12373389
identification of the omega4514 regulatory region, a developmental promoter of myxococcus xanthus that is transcribed in vitro by the major vegetative rna polymerase.	omega4514 is the site of a tn5 lac insertion in the myxococcus xanthus genome that fuses lacz expression to a developmentally regulated promoter. dna upstream of the insertion site was cloned, and the promoter was localized. the promoter resembles vegetative promoters in sequence, and sigma(a) rna polymerase, the major form of rna polymerase in growing m. xanthus, initiated transcription from this promoter in vitro. two complete open reading frames were identified downstream of the promoter and ...	2002	12029052
a novel biosynthetic pathway providing precursors for fatty acid biosynthesis and secondary metabolite formation in myxobacteria.	short chain carboxylic acids are well known as the precursors of fatty acid and polyketide biosynthesis. iso-fatty acids, which are important for the control of membrane fluidity, are formed from branched chain starter units (isovaleryl-coa and isobutyryl-coa), which in turn are derived from the degradation of leucine and valine, respectively. branched chain carboxylic acids are also employed as starter molecules for the biosynthesis of secondary metabolites, e.g. the therapeutically important a ...	2002	12084727
characterization of bcsa mutations that bypass two distinct signaling requirements for myxococcus xanthus development.	the bsga protease is required for starvation-induced development in myxococcus xanthus. bypass suppressors of a bsga mutant were isolated to identify genes that may encode additional components of bsga protease-dependent regulation of development. strain m951 was isolated following tn5 mutagenesis of a bsga mutant and was capable of forming fruiting bodies and viable spores in the absence of the bsga protease. the tn5omega951 insertion was localized to a gene, bcsa, that encodes a protein that h ...	2002	12193631
role of frua and csga genes in gene expression during development of myxococcus xanthus. analysis by two-dimensional gel electrophoresis.	two genes, frua and csga, encoding a putative transcription factor and c-factor, respectively, are essential for fruiting body formation of myxococcus xanthus. to investigate the role of frua and csga genes in developmental gene expression, developing cells as well as vegetative cells of m. xanthus wild-type, frua::tc, and csga731 strains were pulse-labeled with [(35)s]methionine, and the whole cell proteins were analyzed using two-dimensional immobilized ph gradient/sds-page. differences in pro ...	2002	11997385
control of secondary metabolite congener distributions via modulation of the dissolved oxygen tension.	many secondary metabolites, including various polyketides, require complex enzymatic pathways for modification into their final biologically active forms. limitation of the dissolved oxygen supplied during cultivation of various microbial strains can decrease the activity of cytochrome p-450 monooxygenases required for the processing of pathway intermediates into their final forms, resulting in the accumulation of these intermediates as the primary products. here, a generalized oxygen-limited cu ...	2002	12363340
modeling alignment and movement of animals and cells.	schools of fish and flocks of birds are examples for groups of individuals moving in a highly organized way. individuals adapt their orientation and speed to that of their (nearest) neighbors. adaptation of orientation can also be found on the cellular and subcellular level and is called alignment. a model for alignment and movement is derived on the basis of reaction transport equations in one space dimension. existence of solutions is shown and long time behavior of the system is described. th ...	2002	12373346
[isolation and disruption analysis of a developmental gene of myxococcus xanthus].	frub is an associated protein of frua, a transcription factor essential for the development of myxococcus xanthus. degenerate oligonucleotide primers were designed based on the n-terminal amino acid sequence of frub. using genomic dna as template, an approximate 110 bp fragment was generated and further served as a probe to screen a small genomic library of m. xanthus. a 4.5 kb saci fragment was isolated on the basis of its homology to the probe. disruption of frub delayed the morphogenesis of f ...	2002	12557372
[viability of lyophilized cells of myxococcus xanthus ukm 10041 and polyangium cellulosum ukm 10043 in presence of different antioxidants].	it has been established that addition of antioxidants: cystamine, ionol, alpha-tocopherol to protective media (saccharose-gelatin agar) does not affect considerably viability of lyophillized cells of cultures myxococcus xanthus ucm 10041 and polyangium cellulosum ucm 10043. experimentally obtained and predicted data on the survival of cells of m. xanthus ucm 10041 and p. cellulosum ucm 10043 are the values of the same order which evidences for the possibility of the use of quick test for predict ...	2002	12557487
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
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
chemosensory regulation of developmental gene expression in myxococcus xanthus.	the delta-proteobacterium myxococcus xanthus coordinates its motility during aggregation and fruiting body formation. while searching for chemotaxis genes in m. xanthus, we identified a third chemotaxis-like gene cluster, the che3 cluster, encoding homologs to two methyl-accepting chemotaxis proteins (mcps), a chew, a hybrid chea, a cheb, a cher, but no chey. mutations in mcp3a, mcp3b, and chea3 did not show obvious defects in motility or chemotaxis but did affect the timing of entry into develo ...	2003	12566562
the intp c-terminal segment is not required for excision of bacteriophage mx8 from the myxococcus xanthus chromosome.	during lysogenization of myxophage mx8, phage dna can be integrated into the attb site of the myxococcus xanthus chromosome through site-specific recombination. we previously demonstrated that the mx8 attp site is located within the coding sequence of the mx8 intp gene. hence, the integration of mx8 into the m. xanthus chromosome results in the conversion of the 112-amino-acid c-terminal segment of the intp protein into a 13-amino-acid c-terminal segment of a new protein, intr. to examine whethe ...	2003	12644488
coupling gene expression and multicellular morphogenesis during fruiting body formation in myxococcus xanthus.	a recurring theme in morphogenesis is the coupling of the expression of genes that drive morphogenesis and the morphogenetic process per se. this coupling ensures that gene expression and morphogenesis are carried out in synchrony. morphogenesis of the spore-filled fruiting bodies in myxococcus xanthus illustrates this coupling in the construction of a multicellular structure. fruiting body formation involves two stages: aggregation of cells into mounds and the position-specific sporulation of c ...	2003	12657040
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
light-induced carotenogenesis in myxococcus xanthus: functional characterization of the ecf sigma factor carq and antisigma factor carr.	illumination of dark-grown myxococcus xanthus with blue light leads to the induction of carotenoid synthesis. central to this response is the activation of the light-inducible promoter, pcarqrs, and the transcription of three downstream genes, carq, carr and cars. sequence analysis predicted that carq is a member of the ecf (extracytoplasmic function) subfamily of rna polymerase sigma factors, and that carr is an inner membrane protein. genetic analysis strongly implied that carr is an antisigma ...	2003	12657058
extracellular polysaccharides mediate pilus retraction during social motility of myxococcus xanthus.	myxococcus xanthus is a gram-negative bacterium with a complex life cycle that includes vegetative swarming and fruiting-body formation. social (s)-motility (coordinated movement of large cell groups) requires both type iv pili and fibrils (extracellular matrix material consisting of polysaccharides and protein). little is known about the role of this extracellular matrix, or fibril material, in pilus-dependent motility. in this study, mutants lacking fibril material and, therefore, s-motility w ...	2003	12704238
lanthanum fixation by myxococcus xanthus: cellular location and extracellular polysaccharide observation.	myxococcus xanthus is a soil bacterium of the myxobacteria group and is abundant in almost all soils. its role in soil ecology is considered significant. one noteworthy characteristic of the bacterium is that it produces large quantities of extracellular polymeric substances (eps). it is also known that its biomass has the capacity to fix heavy metals. here it is reported that m. xanthus was able to accumulate 0.6 mmol of la per g of wet biomass and/or 0.99 mmol per g of dry biomass. transmissio ...	2003	12729693
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
role of two novel two-component regulatory systems in development and phosphatase expression in myxococcus xanthus.	we have cloned a two-component regulatory system (phor2-phop2) of myxococcus xanthus while searching for genes that encode proteins with phosphatase activity, where phor2 encodes the histidine kinase and phop2 encodes the response regulator. a second system, phor3-phop3, was identified and isolated by using phop2 as a probe. these two systems are quite similar, sharing identities along the full-length proteins of 52% on the histidine kinases and 64% on the response regulators. the predicted stru ...	2003	12562808
cis elements necessary for developmental expression of a myxococcus xanthus gene that depends on c signaling.	cell contact-mediated c signaling coordinates morphogenesis and gene expression during development of myxococcus xanthus. one promoter that depends on c signaling for transcription lies upstream of omega4403, the site of a tn5 lac insertion in the genome. the omega4403 promoter has a c-box sequence centered at -49 bp that matches the consensus 5'-cayyccy-3', which is found in several c-signal-dependent promoters. mutational analysis of the omega4403 promoter region was performed to test the impo ...	2003	12562812
myxovirescin analogues via macrocyclic ring-closing metathesis.	a short, efficient route has been developed to analogues of myxovirescin using ring-closing metathesis whereby the antibacterial activity has been retained.	2003	12565921
a novel regulatory gene for light-induced carotenoid synthesis in the bacterium myxococcus xanthus.	myxococcus xanthus cells respond to blue light by producing carotenoids. light triggers a network of regulatory actions that lead to the transcriptional activation of the carotenoid genes. by screening the colour phenotype of a collection of tn5-lac insertion mutants, we have isolated a new mutant devoid of carotenoid synthesis. we map the transposon insertion, which co-segregates with the mutant phenotype, to a previously unknown gene designated here as carf. an in frame deletion within carf ca ...	2003	12519205
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
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
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
construction and evaluation of a plasmid vector for the expression of recombinant lipoproteins in escherichia coli.	outer membrane lipoproteins are emerging as key targets for protective immunity to many bacterial pathogens. heterologous expression of lipoproteins in escherichia coli does not always result in high level expression of acylated recombinant protein. thus, these proteins do not take up their correct membrane topology and are lacking the immunostimulatory properties endowed by the lipid. to this end, we have designed a lipoprotein expression vector (pdump) that results in the production of fusion ...	2003	12583997
cell shape, division and development: the 2002 american society for microbiology (asm) conference on prokaryotic development.	in the last decade, the use of cytological techniques, together with the analysis of complete genomes, has dramatically advanced our understanding of bacterial development. work on several well-developed model systems such as bacillus subtilis, caulobacter crescentus, myxococcus xanthus and streptomyces spp., has provided us with an in-depth understanding of processes such as sporulation, multicellular behaviour and the bacterial cell cycle. at the same time, these studies have revolutionized ou ...	2003	12603749
regulation of frua expression during vegetative growth and development of myxococcus xanthus.	expression of the frua gene, encoding a putative transcription factor essential for fruiting body formation of myxococcus xanthus, is specifically activated during development. in the present study, we have analyzed the mechanism of the transcriptional regulation of frua expression. from gel retardation and footprinting assays using various frua regulatory regions as probes and competitors, a protein designated factor x was found to specifically bind to a sequence (xbs) located downstream of the ...	2003	12736531
novel developmental genes, frucd, of myxococcus xanthus: involvement of a cell division protein in multicellular development.	myxococcus xanthus is a gram-negative soil bacterium that undergoes multicellular development upon nutrient starvation. in the present study, two novel developmental genes, fruc and frud, of m. xanthus were identified and characterized. the frud protein has significant amino acid sequence similarity to the diviva proteins of many bacteria including bacillus subtilis. vegetative cells of the frud mutant exhibited a filamentous phenotype. the fruc and frud mutants displayed similar delayed-develop ...	2003	12754229
conservation of ornamental stone by myxococcus xanthus-induced carbonate biomineralization.	increasing environmental pollution in urban areas has been endangering the survival of carbonate stones in monuments and statuary for many decades. numerous conservation treatments have been applied for the protection and consolidation of these works of art. most of them, however, either release dangerous gases during curing or show very little efficacy. bacterially induced carbonate mineralization has been proposed as a novel and environmentally friendly strategy for the conservation of deterio ...	2003	12676699
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
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
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
[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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
cloning, sequence analysis and disruption of the mgla gene involved in swarming motility of sorangium cellulosum so ce26, a producer of the antifungal polyketide antibiotic soraphen a.	the myxobacterium sorangium cellulosum so ce26, the producer of the agriculturally important fungicide antibiotic soraphen a, displays coordinated gliding motility (swarming) on agar surfaces. the consequent failure to form detached colonies represents a major obstacle for microbiological and genetic studies, since single cells representing discrete genetic events cannot be reliably separated and propagated as clones. the mgla protein, the product of the mgla gene, has been shown to be a central ...	2004	16233626
a novel bacterial signalling system with a combination of a ser/thr kinase cascade and a his/asp two-component system.	prokaryotes and eukaryotes have long been thought to use very different types of kinases (the his kinases of the 'bacterial' two-component systems versus the 'eukaryotic' ser/thr/tyr kinases) to carry out signal transduction. this paradigm no longer holds true, because both systems are now found together in an increasing number of prokaryotic organisms and 'two-component' his kinase are present in eukaryotes. pioneering work on bacterial protein serine threonine kinases (pstks) has been performe ...	2005	16194223
identification of a protein ser/thr kinase cascade that regulates essential transcriptional activators in myxococcus xanthus development.	pkn8 is a membrane-associated protein ser/thr kinase (pstk) of myxoccocus xanthus that was previously found to associate with a novel cytoplasmic kinase, pkn14. in the present study, mrpc, an essential transcription factor for frua expression during fruiting body development, was identified using a genomic yeast two-hybrid screen with pkn14 as bait. our biochemical studies demonstrated that purified pkn8 and pkn14 are active kinases and that pkn8 is able to phosphorylate pkn14 that forms a tetra ...	2005	16194226
factors that modulate the pkn4 kinase cascade in myxococcus xanthus.	myxococcus xanthus, a gram-negative developmental bacterium, contains a large number of protein ser/thr kinases (pstks). among these pstks, pkn4 is shown to be 6-phosphofructokinase (pfk) kinase. pfk associates with the regulatory domain of pkn4 (pkn4rd) and is activated 2.7-fold upon phosphorylation at thr-226 by pkn4. the activation of pfk is required to consume glycogen accumulated during early development and is essential for efficient sporulation. three new factors, mkapa, mkapb and mkapc h ...	2005	16415588
the dif chemosensory pathway is directly involved in phosphatidylethanolamine sensory transduction in myxococcus xanthus.	myxococcus xanthus cells glide on solid surfaces and are chemotactically stimulated by certain phosphatidylethanolamine species. the dif gene cluster consists of six genes, difabcdeg, five of which encode proteins homologous to known chemotaxis proteins. difa and dife are required for the biosynthesis of fibrils, an extracellular matrix comprised of polysaccharide and protein. chemotactic stimulation by 1,2-o-bis[11-(z)-hexadecenoyl]-sn-glycero-3-phosphatidylethanolamine (16:1 pe) and dilauroyl ...	2005	16102016
fermentation, purification, formulation, and pharmacological evaluation of a prolyl endopeptidase from myxococcus xanthus: implications for celiac sprue therapy.	celiac sprue is a multi-factorial disease characterized by an inflammatory response to ingested wheat gluten and similar proteins in rye and barley. proline-rich gluten peptides from wheat, rye, and barley are relatively resistant to gastrointestinal digestion, and therefore persist in the intestinal lumen to elicit immunopathology in genetically susceptible individuals. in this study, we characterize the in vitro gluten detoxifying properties of a therapeutically promising prolyl endopeptidase ...	2005	16136593
nitrate-dependent activation of the dif signaling pathway of myxococcus xanthus mediated by a narx-difa interspecies chimera.	myxococcus xanthus fibril exopolysaccharide (eps), essential for the social gliding motility and development of this bacterium, is regulated by the dif chemotaxis-like pathway. difa, an mcp homolog, is proposed to mediate signal input to the dif pathway. however, difa lacks a prominent periplasmic domain, which in classical chemoreceptors is responsible for signal perception and for initiating transmembrane signaling. to investigate the signaling properties of difa, we constructed a narx-difa (n ...	2005	16159775
dna replication during sporulation in myxococcus xanthus fruiting bodies.	during the developmental process of the gram-negative soil bacterium myxococcus xanthus, vegetatively growing rod cells differentiate to ultimately become metabolically quiescent and environmentally resistant myxospores encased within fruiting bodies. this program, initiated by nutrient deprivation, is propagated by both cell-autonomous and cell-nonautonomous signals. our goal was to determine whether m. xanthus, like many other developmental systems, uses cell-cycle cues to regulate and control ...	2005	16183740