title: Autoinducer-2-producing protein LuxS, a novel salt- and chloride-induced protein in the moderately halophilic bacterium Halobacillus halophilus.
abstract: The moderately halophilic bacterium Halobacillus halophilus carries a homologue of LuxS, a protein involved in the activated methyl cycle and the production of autoinducer-2, which mediates quorum sensing between certain species. luxS of H. halophilus is part of an operon that encodes an S-adenosylmethionine-dependent methyltransferase, a cysteine synthase, and a beta-cystathionine lyase. Expression of luxS was growth phase dependent, with maximal expression in the mid-exponential growth phase. In addition, transcription of luxS was strictly salt dependent; maximal mRNA concentrations were observed with 2.0 M NaCl in the growth medium. Chloride ions stimulated luxS transcription by a factor of three. Western blot analyses demonstrated a growth phase- and salinity-dependent production of LuxS. Moreover, cellular LuxS levels were strictly chloride dependent. Maximal accumulation of LuxS was observed at 0.5 to 1.0 M Cl(-) and depended on the salinity.
authors.affiliation: Section Microbiology, Department Biology I, Ludwig Maximilians University, Munich, Germany.
authors.forename: Xaver
authors.initials: X
authors.lastname: Sewald
authors.forename: Stephan H
authors.initials: SH
authors.lastname: Saum
authors.forename: Peter
authors.initials: P
authors.lastname: Palm
authors.forename: Friedhelm
authors.initials: F
authors.lastname: Pfeiffer
authors.forename: Dieter
authors.initials: D
authors.lastname: Oesterhelt
authors.forename: Volker
authors.initials: V
authors.lastname: Müller
mesh_terms: D000595:Amino Acid Sequence; D001406:Bacillaceae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013437:Carbon-Sulfur Lyases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002712:Chlorides / Q000494:pharmacology*; D015964:Gene Expression Regulation, Bacterial; D006714:Homoserine / Q000031:analogs & derivatives* / Q000096:biosynthesis; D007783:Lactones; D008969:Molecular Sequence Data; D012965:Sodium Chloride / Q000494:pharmacology*; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D002712:Chlorides; D007783:Lactones; C091088:N-octanoylhomoserine lactone; D012965:Sodium Chloride; D006714:Homoserine; D013437:Carbon-Sulfur Lyases; C117753:LuxS protein, Bacteria