title: N-glycosylation of Campylobacter jejuni surface proteins promotes bacterial fitness.
abstract: Campylobacter jejuni is the etiologic agent of human bacterial gastroenteritis worldwide. In contrast, despite heavy colonization, C. jejuni maintains a commensal mode of existence in chickens. The consumption of contaminated chicken products is thought to be the principal mode of C. jejuni transmission to the human population. C. jejuni harbors a system for N-linked protein glycosylation that has been well characterized and modifies more than 60 periplasmic and membrane-bound proteins. However, the precise role of this modification in the biology of C. jejuni remains unexplored. We hypothesized that the N-glycans protect C. jejuni surface proteins from the action of gut proteases. The C. jejuni pglB mutant, deficient in the expression of the oligosaccharyltransferase, exhibited reduced growth in medium supplemented with chicken cecal contents (CCC) compared with that of wild-type (WT) cells. Inactivation of the cecal proteases by heat treatment or with protease inhibitors completely restored bacterial viability and partially rescued bacterial growth. Physiological concentrations of trypsin, but not chymotrypsin, also reduced C. jejuni pglB mutant CFU. Live or dead staining indicated that CCC preferentially influenced C. jejuni growth as opposed to bacterial viability. We identified multiple chicken cecal proteases by mass fingerprinting. The use of protease inhibitors that target specific classes indicated that both metalloproteases and serine proteases were involved in the attenuated growth of the oligosaccharyltransferase mutant. In conclusion, protein N-linked glycosylation of surface proteins may enhance C. jejuni fitness by protecting bacterial proteins from cleavage due to gut proteases.
authors: Alberta Glycomics Centre and Department of Biological Sciences, University of Alberta, Edmonton, Canada. abofu.alemka@innovotech.ca
authors: Abofu
authors: A
authors: Alemka
authors: Harald
authors: H
authors: Nothaft
authors: Jing
authors: J
authors: Zheng
authors: Christine M
authors: CM
authors: Szymanski
mesh_terms: D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000502:physiology*; D002169:Campylobacter Infections / Q000378:metabolism / Q000382:microbiology; D016123:Campylobacter jejuni / Q000502:physiology*; D002432:Cecum / Q000382:microbiology; D002645:Chickens / Q000382:microbiology; D015169:Colony Count, Microbial; D006031:Glycosylation; D006602:Hexosyltransferases / Q000172:deficiency / Q000378:metabolism; D008565:Membrane Proteins / Q000172:deficiency / Q000378:metabolism; D010447:Peptide Hydrolases / Q000378:metabolism; D011135:Polysaccharides, Bacterial / Q000502:physiology*; D011201:Poultry Diseases / Q000382:microbiology
chemical_list: D001425:Bacterial Outer Membrane Proteins; D008565:Membrane Proteins; D011135:Polysaccharides, Bacterial; D006602:Hexosyltransferases; C025620:dolichyl-diphosphooligosaccharide - protein glycotransferase; D010447:Peptide Hydrolases