title: The periplasmic chaperone Skp is required for successful Salmonella Typhimurium infection in a murine typhoid model.
abstract: The alternative sigma factor σ(E) (rpoE) is essential for survival in vivo of Salmonella Typhimurium but is dispensable during growth in the laboratory. We have been identifying σ(E)-regulated genes and studying their regulation and function to elucidate their potential role in the severe attenuation of S. Typhimurium rpoE mutants. In this study we identify five promoters that control the rseP, yaeT (bamA), skp region. A confirmed σ(E)-dependent promoter, yaeTp1, and a second downstream promoter, yaeTp2, are located within the upstream gene rseP and direct expression of the downstream genes. The only known function of RseP is σ(E) activation, and it is therefore not expected to be essential for S. Typhimurium in vitro. However, it proved impossible to delete the entire rseP gene due to the presence of internal promoters that regulate the essential gene yaeT. We could inactivate rseP by deleting the first third of the gene, leaving the yaeT promoters intact. Like the rpoE mutant, the rseP mutant exhibited severe attenuation in vivo. We were able to delete the entire coding sequence of skp, which encodes a periplasmic chaperone involved in targeting misfolded outer-membrane proteins to the β-barrel assembly machinery. The skp mutant was attenuated in mice after oral and parenteral infection. Virulence could be complemented by providing skp in trans but only by linking it to a heterologous σ(E)-regulated promoter. The reason the skp mutant is attenuated is currently enigmatic, but we know it is not through increased sensitivity to a variety of RpoE-activating host stresses, such as H(2)O(2), polymyxin B and high temperature, or through altered secretion of effector proteins by either the Salmonella pathogenicity island (SPI)-1 or the SPI-2 type III secretion system.
authors.affiliation: School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK.
authors.forename: Gary
authors.initials: G
authors.lastname: Rowley
authors.affiliation: Institute of Molecular Biology, Slovak Academy of Sciences, Dubravska cesta 21, 845 51 Bratislava, Slovak Republik.
authors.forename: Henrieta
authors.initials: H
authors.lastname: Skovierova
authors.affiliation: Institute of Comparative Medicine, Faculty of Veterinary Medicine, University of Glasgow, Bearsden Road, Glasgow G61 1QH, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Stevenson
authors.affiliation: Institute of Molecular Biology, Slovak Academy of Sciences, Dubravska cesta 21, 845 51 Bratislava, Slovak Republik.
authors.forename: Bronislava
authors.initials: B
authors.lastname: Rezuchova
authors.affiliation: Institute of Molecular Biology, Slovak Academy of Sciences, Dubravska cesta 21, 845 51 Bratislava, Slovak Republik.
authors.forename: Dagmar
authors.initials: D
authors.lastname: Homerova
authors.affiliation: Institute of Comparative Medicine, Faculty of Veterinary Medicine, University of Glasgow, Bearsden Road, Glasgow G61 1QH, UK.
authors.forename: Claire
authors.initials: C
authors.lastname: Lewis
authors.affiliation: Institute of Comparative Medicine, Faculty of Veterinary Medicine, University of Glasgow, Bearsden Road, Glasgow G61 1QH, UK.
authors.forename: Aileen
authors.initials: A
authors.lastname: Sherry
authors.affiliation: Institute of Molecular Biology, Slovak Academy of Sciences, Dubravska cesta 21, 845 51 Bratislava, Slovak Republik.
authors.forename: Jan
authors.initials: J
authors.lastname: Kormanec
authors.affiliation: Institute of Comparative Medicine, Faculty of Veterinary Medicine, University of Glasgow, Bearsden Road, Glasgow G61 1QH, UK.
authors.forename: Mark
authors.initials: M
authors.lastname: Roberts
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D005656:Fungal Proteins / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D018869:Heat-Shock Response; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D019897:Periplasm / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D018085:Regulon; D012486:Salmonella typhimurium / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism; D015719:Single-Strand Specific DNA and RNA Endonucleases / Q000378:metabolism; D014158:Transcription, Genetic; D014435:Typhoid Fever / Q000382:microbiology / Q000473:pathology*; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; D005656:Fungal Proteins; D018832:Molecular Chaperones; D012808:Sigma Factor; C063202:sporulation-specific sigma factors; C526098:Endonuclease S1, Aspergillus; D015719:Single-Strand Specific DNA and RNA Endonucleases