title: Glycosylation of DsbA in Francisella tularensis subsp. tularensis.
abstract: In Francisella tularensis subsp. tularensis, DsbA has been shown to be an essential virulence factor and has been observed to migrate to multiple protein spots on two-dimensional electrophoresis gels. In this work, we show that the protein is modified with a 1,156-Da glycan moiety in O-linkage. The results of mass spectrometry studies suggest that the glycan is a hexasaccharide, comprised of N-acetylhexosamines, hexoses, and an unknown monosaccharide. Disruption of two genes within the FTT0789-FTT0800 putative polysaccharide locus, including a galE homologue (FTT0791) and a putative glycosyltransferase (FTT0798), resulted in loss of glycan modification of DsbA. The F. tularensis subsp. tularensis ΔFTT0798 and ΔFTT0791::Cm mutants remained virulent in the murine model of subcutaneous tularemia. This indicates that glycosylation of DsbA does not play a major role in virulence under these conditions. This is the first report of the detailed characterization of the DsbA glycan and putative role of the FTT0789-FTT0800 gene cluster in glycan biosynthesis.
authors.affiliation: Defence Science and Technology Laboratory, Porton Down, Wiltshire, UK.
authors.forename: Rebecca M
authors.initials: RM
authors.lastname: Thomas
authors.forename: Susan M
authors.initials: SM
authors.lastname: Twine
authors.forename: Kelly M
authors.initials: KM
authors.lastname: Fulton
authors.forename: Luc
authors.initials: L
authors.lastname: Tessier
authors.forename: Sara L N
authors.initials: SL
authors.lastname: Kilmury
authors.forename: Wen
authors.initials: W
authors.lastname: Ding
authors.forename: Nicholas
authors.initials: N
authors.lastname: Harmer
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Michell
authors.forename: Petra C F
authors.initials: PC
authors.lastname: Oyston
authors.forename: Richard W
authors.initials: RW
authors.lastname: Titball
authors.forename: Joann L
authors.initials: JL
authors.lastname: Prior
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D005260:Female; D005604:Francisella tularensis / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity*; D006031:Glycosylation; D051379:Mice; D008807:Mice, Inbred BALB C; D005810:Multigene Family / Q000235:genetics / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014406:Tularemia / Q000235:genetics / Q000382:microbiology*; D014774:Virulence / Q000235:genetics / Q000502:physiology; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D037521:Virulence Factors