title: Role of anionic charges of osmoregulated periplasmic glucans of Salmonella                      enterica serovar Typhimurium SL1344 in mice virulence.
abstract: opgB gene of Salmonella                         enterica serovar Typhimurium was identified earlier in a genome-wide screen for mice virulence (Valentine et al. in Infect Immun 66:3378-3383, 1998). Although mutation in opgB resulted in avirulent Salmonella strain, how this gene contributes to pathogenesis remains unclear. Based on DNA homology, opgB is predicted to be responsible for adding phosphoglycerate residues to osmoregulated periplasmic glucans (OPGs) giving them anionic characteristics. In Escherichia                         coli, yet another gene, opgC, is also reported to contribute to anionic characteristics of OPGs by adding succinic acid residues. We constructed opgB, opgC, and opgBC double mutants of S. enterica serovar Typhimurium strain SL1344. As predicted opgBC mutant synthesized neutral OPGs that were devoid of any anionic substituents. However, opgB, opgC, and opgBC mutations had no significant impact on mice virulence as well as on competitive organ colonization. In low osmotic conditions, opgB, opgC, and opgBC mutants exhibited delay in growth initiation in the presence of sodium deoxycholate. Anionic substituents of OPGs from Salmonella although appear to be needed to overcome resistance of deoxycholate in hypoosmotic growth media, no evidence was found for their role in mice virulence.
authors.affiliation: Environmental Microbial and Food Safety Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Agricultural Research Service, USDA, 10300 Baltimore Avenue, Bldg. 173, BARC-E, Beltsville, MD 20705-2350, USA. arvind.bhagwat@ars.usda.gov
authors.forename: Arvind A
authors.initials: AA
authors.lastname: Bhagwat
authors.forename: Porteen
authors.initials: P
authors.lastname: Kannan
authors.forename: Yi Ning
authors.initials: YN
authors.lastname: Leow
authors.forename: Mahesh
authors.initials: M
authors.lastname: Dharne
authors.forename: Allen
authors.initials: A
authors.lastname: Smith
mesh_terms: D000818:Animals; D000838:Anions / Q000737:chemistry; D003840:Deoxycholic Acid / Q000737:chemistry; D005798:Genes, Bacterial; D005936:Glucans / Q000737:chemistry*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009154:Mutation; D009997:Osmotic Pressure; D019897:Periplasm / Q000737:chemistry*; D012486:Salmonella typhimurium / Q000737:chemistry / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity*; D019802:Succinic Acid / Q000737:chemistry; D014774:Virulence
chemical_list: D000838:Anions; D005936:Glucans; D003840:Deoxycholic Acid; D019802:Succinic Acid