title: Role for HtrA in stress induction and virulence potential in Listeria monocytogenes.
abstract: In silico analysis of the Listeria monocytogenes genome revealed lmo0292, a gene predicted to encode a HtrA-like serine protease. A stable insertion mutant was constructed, revealing a requirement for htrA in the listerial response to heat, acid, and penicillin stress. Transcriptional analysis revealed that htrA is not induced in response to heat shock but is induced in response to low pH and penicillin G stress. Furthermore, htrA expression was shown to be dependent upon the LisRK two-component sensor-kinase, a system known to respond to changes in integrity of the cell envelope. In addition, we demonstrated that a second in-frame start codon, upstream of that previously annotated for L. monocytogenes htrA, incorporating a putative signal sequence appears to influence virulence potential. Finally, a significant virulence defect was observed for the htrA mutant, indicating that this gene is required for full virulence in mice. Our findings suggest that L. monocytogenes lmo0292 encodes an HtrA-like serine protease that is not part of the classical heat shock response but is involved in stress responses and virulence.
authors.affiliation: Department of Microbiology and Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland.
authors.forename: Helena M
authors.initials: HM
authors.lastname: Stack
authors.forename: Roy D
authors.initials: RD
authors.lastname: Sleator
authors.forename: Megan
authors.initials: M
authors.lastname: Bowers
authors.forename: Colin
authors.initials: C
authors.lastname: Hill
authors.forename: Cormac G M
authors.initials: CG
authors.lastname: Gahan
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018869:Heat-Shock Response; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008089:Listeria monocytogenes / Q000201:enzymology / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology*; D008088:Listeriosis / Q000382:microbiology; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D010400:Penicillin G / Q000494:pharmacology; D017422:Sequence Analysis, DNA; D012697:Serine Endopeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; D006360:Heat-Shock Proteins; D012697:Serine Endopeptidases; D010400:Penicillin G