title: Reduced amounts of LPS affect both stress tolerance and virulence of Salmonella enterica serovar Dublin.
abstract: Signature-tagged mutagenesis (STM) is a widely used technique for identification of virulence genes in bacterial pathogens. While this approach often generates a large number of mutants with a potential reduction in virulence a major task is subsequently to determine the mechanism by which the mutations influence virulence. Presently, we have characterised a Salmonella enterica serovar Dublin STM mutant that, in addition to having reduced virulence, was also impaired when growing under various stress conditions. The mutation mapped to the manC (rfbM) gene of the O-antigen gene cluster involved in O-antigen synthesis. The O-antigen is a component of the lipopolysaccharide (LPS) forming a unique constituent of the outer membrane of Gram-negative bacteria. While mutations in the O-antigen genes usually eliminate the entire O-antigen side chain we found that the transposon mutant produced intact O-antigen, however, the mutation reduced the amount of LPS.
authors.affiliation: Department of Veterinary Microbiology, Stigboejlen 4, The Royal Veterinary and Agricultural University, DK-1870 Frederiksberg C, Denmark.
authors.forename: Line E
authors.initials: LE
authors.lastname: Thomsen
authors.forename: Mark S
authors.initials: MS
authors.lastname: Chadfield
authors.forename: Jennifer
authors.initials: J
authors.lastname: Bispham
authors.forename: Timothy S
authors.initials: TS
authors.lastname: Wallis
authors.forename: John E
authors.initials: JE
authors.lastname: Olsen
authors.forename: Hanne
authors.initials: H
authors.lastname: Ingmer
mesh_terms: D000818:Animals; D018441:Biofilms / Q000254:growth & development; D002460:Cell Line; D002874:Chromosome Mapping; D005798:Genes, Bacterial; D008070:Lipopolysaccharides / Q000378:metabolism*; D051379:Mice; D009068:Movement; D016254:Mutagenesis, Insertional / Q000379:methods; D009154:Mutation; D009713:Nucleotidyltransferases / Q000235:genetics / Q000378:metabolism; D019081:O Antigens / Q000096:biosynthesis / Q000235:genetics; D016897:Respiratory Burst; D019779:Salmonella enterica / Q000737:chemistry* / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity*; D013696:Temperature; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D008070:Lipopolysaccharides; D019081:O Antigens; D037521:Virulence Factors; D009713:Nucleotidyltransferases; C026917:mannose 1-phosphate guanylyltransferase