title: Regulation of expression of the pilA gene in Myxococcus xanthus.
abstract: Type IV pili are required for social gliding motility in Myxococcus xanthus. In this work, the expression of pilin (the pilA gene product) during vegetative growth and fruiting-body development was examined. A polyclonal antibody against the pilA gene product (prepilin) was prepared, along with a pilA-lacZ fusion, and was used to assay expression of pilA in M. xanthus in different mutant backgrounds. pilA expression required the response regulator pilR but was negatively regulated by the putative sensor kinase pilS. pilA expression did not require pilB, pilC, or pilT. pilA was also autoregulated; a mutation which altered an invariant glutamate five residues from the presumed prepilin processing site eliminated this autoregulation, as did a deletion of the pilA gene. Primer extension and S1 nuclease analysis identified a sigma54 promoter upstream of pilA, consistent with the homology of pilR to the NtrC family of response regulators. Expression of pilA was found to be developmentally regulated; however, the timing of this expression pattern was not entirely dependent on pilS or pilR. Finally, pilA expression was induced by high nutrient concentrations, an effect that was also not dependent on pilS or pilR.
authors.affiliation: Department of Biochemistry, Stanford University School of Medicine, California 94305, USA.
authors.forename: S S
authors.initials: SS
authors.lastname: Wu
authors.forename: D
authors.initials: D
authors.lastname: Kaiser
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D003470:Culture Media; D004268:DNA-Binding Proteins; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D036781:Fimbriae Proteins; D010861:Fimbriae, Bacterial / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D009024:Morphogenesis; D016941:Myxococcus xanthus / Q000235:genetics* / Q000254:growth & development; D011401:Promoter Regions, Genetic; D051877:RNA Polymerase Sigma 54; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D017384:Sequence Deletion; D012808:Sigma Factor / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D004268:DNA-Binding Proteins; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; D012808:Sigma Factor; D014157:Transcription Factors; C080687:pilS protein, Bacteria; C074774:pilR protein, Pseudomonas aeruginosa; D036781:Fimbriae Proteins; D012321:DNA-Directed RNA Polymerases; D051877:RNA Polymerase Sigma 54