title: Involvement of Clp protease activity in modulating the Bacillus subtilissigmaw stress response.
abstract: The induction of Bacillus subtilis genes controlled by the extracytoplasmic function alternative sigma factor sigmaW is strongly impaired in a strain deleted for the ClpP peptidase gene and in a double knockout of the ClpX and ClpE ATPase genes. Truncated soluble forms of the sigmaW anti-sigma factor RsiW are stabilized in a clpP minus strain as revealed by the green fluorescent reporter protein fused to the N-terminus of RsiW and by pulse-chase experiments. Conserved alanine residues are present in the transmembrane region of RsiW, and mutations in these positions abolish induction of sigmaW-controlled genes. Following alkaline shock, a truncated cytoplasmic form of RsiW is detectable in a strain expressing a triple alanine mutant allele of rsiW. These data point to a mechanism where the trans-membrane segment of RsiW contains a cryptic proteolytic tag that is uncovered as a result of intramembrane proteolysis of RsiW by RasP (YluC). After RasP-clipped RsiW is detached from the membrane, this proteolytic tag becomes crucial for the complete degradation of RsiW by cytoplasmic proteases and the release of sigmaW. ClpXP plays a major role in this third proteolytic step of stress-induced degradation of RsiW. Overexpression of SsrA-tagged green fluorescent protein as a ClpXP substrate protein reduces alkali induction of a sigmaW-controlled gene by a factor of about three, indicating that a titration mechanism is able to tune the sigmaW-mediated stress response to the cellular state.
authors.affiliation: Institute of Genetics, University of Bayreuth, D-95440 Bayreuth, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Zellmeier
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Schumann
authors.forename: Thomas
authors.initials: T
authors.lastname: Wiegert
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism; D000409:Alanine / Q000737:chemistry / Q000235:genetics; D000468:Alkalies / Q000494:pharmacology; D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D002462:Cell Membrane; D017124:Conserved Sequence; D049071:Endopeptidase Clp / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary / Q000235:genetics; D018085:Regulon / Q000235:genetics; D012808:Sigma Factor / Q000235:genetics* / Q000378:metabolism*
chemical_list: D000468:Alkalies; D001426:Bacterial Proteins; C413458:SigW protein, Bacillus subtilis; D012808:Sigma Factor; D049071:Endopeptidase Clp; D000251:Adenosine Triphosphatases; D000409:Alanine