Glycosylation of DsbA in Francisella tularensis subsp. tularensis

• Published in: Journal of Bacteriology 2011-10, Vol.193 (19), p.5498-5509
• Main Authors: Thomas, Rebecca M, Twine, Susan M, Fulton, Kelly M, Tessier, Luc, Kilmury, Sara L. N, Ding, Wen, Harmer, Nicholas, Michell, Stephen L, Oyston, Petra C. F, Titball, Richard W, Prior, Joann L
• Format: Article
• Language: English
• Subjects: animal models; Animals; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacteriology; Biological and medical sciences; biosynthesis; Electrophoresis, Gel, Two-Dimensional; Female; Francisella tularensis - genetics; Francisella tularensis - metabolism; Francisella tularensis - pathogenicity; Francisella tularensis subsp. tularensis; Fundamental and applied biological sciences. Psychology; gels; genes; Glycosylation; hexoses; loci; Mass spectrometry; Mice; Mice, Inbred BALB C; Microbiology; Miscellaneous; Molecular Biology of Pathogens; Multigene Family - genetics; Multigene Family - physiology; mutants; Mutation; Reverse Transcriptase Polymerase Chain Reaction; tularemia; Tularemia - genetics; Tularemia - microbiology; two-dimensional gel electrophoresis; Virology; virulence; Virulence - genetics; Virulence - physiology; Virulence Factors - genetics; Virulence Factors - metabolism
• ISSN: 0021-9193; 1098-5530; 1067-8832
• DOI: 10.1128/JB.00438-11

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.