title: The lonS gene regulates swarmer cell differentiation of Vibrio parahaemolyticus.
abstract: Vibrio parahaemolyticus differentiates from a polarly flagellated, short, rod-shaped cell known as the swimmer to the elongated, hyperflagellated, and multinucleated swarmer cell type when it is grown on a surface. The swarmer is adapted to movement over and colonization of surfaces. To understand the signal transduction mechanism by which the bacterium recognizes surfaces and reprograms gene expression, we isolated a new class of mutants defective in surface sensing. These mutants were constitutive for swarmer cell gene expression, inappropriately expressing high levels of a swarmer cell gene fusion product when grown in liquid. They showed no defect in the swimming motility system, unlike all previously isolated constitutive mutants which have defects in the alternate, polar motility system. The lesions in the majority of the newly isolated mutants were found to be in a gene, lonS, which encodes a polypeptide exhibiting 81% sequence identity to the Escherichia coli Lon protein, an ATP-dependent protease. Upstream sequences preceding the lonS coding region resemble a heat shock promoter, and the homology extends to sequences flanking lonS. The gene order appears to be clpX lonS hupB, like the organization of the E. coli locus. V. parahaemolyticus lonS complemented E. coli lon mutants to restore UV resistance and capsular polysaccharide regulation to that of the wild type. Vibrio lonS mutants were UV sensitive. In addition, when grown in liquid and examined in a light microscope, lonS mutant cells were extremely long and thus resembled swarmer cells harvested from a surface.
authors.affiliation: Department of Microbiology, The University of Iowa, Iowa City 52242, USA.
authors.forename: B J
authors.initials: BJ
authors.lastname: Stewart
authors.forename: J L
authors.initials: JL
authors.lastname: Enos-Berlage
authors.forename: L L
authors.initials: LL
authors.lastname: McCarter
mesh_terms: D049069:ATP-Dependent Proteases; D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D003470:Culture Media; D004926:Escherichia coli / Q000528:radiation effects; D029968:Escherichia coli Proteins; D005407:Flagella / Q000502:physiology; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D005798:Genes, Bacterial / Q000235:genetics*; D005816:Genetic Complementation Test; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000502:physiology; D008969:Molecular Sequence Data; D009154:Mutation; D049070:Protease La; D011836:Radiation Tolerance; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D017422:Sequence Analysis, DNA; D012697:Serine Endopeptidases / Q000235:genetics* / Q000502:physiology; D014466:Ultraviolet Rays; D014736:Vibrio parahaemolyticus / Q000235:genetics* / Q000502:physiology / Q000528:radiation effects
chemical_list: D003470:Culture Media; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; D011993:Recombinant Fusion Proteins; D049069:ATP-Dependent Proteases; D012697:Serine Endopeptidases; C483567:Lon protein, E coli; D049070:Protease La