title: Single, double and triple mutants of Salmonella enterica serovar Typhimurium degP (htrA), degQ (hhoA) and degS (hhoB) have diverse phenotypes on exposure to elevated temperature and their growth in vivo is attenuated to different extents.
abstract: DegP (HtrA) is a well-studied protease involved in survival of bacteria under stress conditions in vitro and in vivo. There are two paralogues of DegP in the Salmonella enterica serovar Typhimurium genome, DegQ and DegS. In order to understand more about the biological significance of this gene family, a series of deg-deletion mutants was generated in S. Typhimurium strain SL3261 by allelic replacement. At elevated temperature in vitro, the viability of degP and degS mutants was reduced when compared with the parent strain whereas the viability of a degQ mutant was not significantly affected. The viability of a double degP-degS mutant at elevated temperature was severely decreased when compared with the respective single mutants or, interestingly, with a triple degP-degQ-degS mutant. All the deg deletions were transduced into the mouse-virulent strain SL1344 and the resultant mutants were injected intravenously into BALB/c mice to test virulence. degP and degS single mutants and all combinations of double and triple mutants were attenuated to different degrees, whereas the single degQ mutant was as virulent as the wild-type strain. Thus, within this gene family, degP and degS appear important for survival at elevated temperature and are necessary for full virulence, whereas a single degQ deletion appears to have no clear role in survival and growth at elevated temperature or in mice.
authors.affiliation: Wolfson Institute for Biomedical Research, University College London, Cruciform Building, Gower Street, London WC1E 6BT, UK. elaine_mo@msn.com
authors.forename: Elaine
authors.initials: E
authors.lastname: Mo
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Peters
authors.forename: Chrissie
authors.initials: C
authors.lastname: Willers
authors.forename: Duncan J
authors.initials: DJ
authors.lastname: Maskell
authors.forename: Ian G
authors.initials: IG
authors.lastname: Charles
mesh_terms: D000818:Animals; D001681:Biological Assay; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D006360:Heat-Shock Proteins / Q000235:genetics / Q000502:physiology*; D018869:Heat-Shock Response / Q000502:physiology; D008099:Liver / Q000382:microbiology; D051379:Mice; D008807:Mice, Inbred BALB C; D016254:Mutagenesis, Insertional; D033903:Periplasmic Proteins / Q000235:genetics / Q000502:physiology*; D010641:Phenotype; D016133:Polymerase Chain Reaction; D012480:Salmonella Infections / Q000382:microbiology* / Q000473:pathology; D012486:Salmonella typhimurium / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development* / Q000472:pathogenicity; D012697:Serine Endopeptidases / Q000235:genetics / Q000502:physiology*; D013154:Spleen / Q000382:microbiology; D014774:Virulence
chemical_list: D004269:DNA, Bacterial; D006360:Heat-Shock Proteins; D033903:Periplasmic Proteins; C061682:DegP protease; D012697:Serine Endopeptidases