title: Osmoregulated periplasmic glucans synthesis gene family of Shigella  flexneri.
abstract: Osmoregulated periplasmic glucans (OPGs) of food- and water-borne enteropathogen Shigella flexneri were characterized. OPGs were composed of 100% glucose with 2-linked glucose as the most abundant residue with terminal glucose, 2-linked and 2,6-linked glucose also present in high quantities. Most dominant backbone polymer chain length was seven glucose residues. Individual genes from the opg gene family comprising of a bicistronic operon opgGH, opgB, opgC and opgD were mutagenized to study their effect on OPGs synthesis, growth in hypo-osmotic media and ability to invade HeLa cells. Mutation in opgG and opgH abolished OPGs biosynthesis, and mutants experienced longer lag time to initiate growth in hypo-osmotic media. Longer lag times to initiate growth in hypo-osmotic media were also observed for opgC and opgD mutants but not for opgB mutant. All opg mutants were able to infect HeLa cells, and abolition of OPGs synthesis did not affect actin polymerization or plaque formation. Ability to synthesize OPGs was beneficial to bacteria in order to initiate growth under low osmolarity conditions, in vitro mammalian cell invasion assays, however, could not discriminate whether OPGs were required for basic aspect of Shigella virulence.
  
  
  BACKGROUND
  The online version of this article (doi:10.1007/s00203-009-0538-z) contains supplementary material, which is available to authorized users.
authors.affiliation: College of Food Science and Technology, Northwest A&F University, 712100 Yangling, China.
authors.forename: Liu
authors.initials: L
authors.lastname: Liu
authors.forename: Mahesh
authors.initials: M
authors.lastname: Dharne
authors.forename: Porteen
authors.initials: P
authors.lastname: Kannan
authors.forename: Allen
authors.initials: A
authors.lastname: Smith
authors.forename: Jianghong
authors.initials: J
authors.lastname: Meng
authors.forename: Mingtao
authors.initials: M
authors.lastname: Fan
authors.forename: Tara L
authors.initials: TL
authors.lastname: Boren
authors.forename: Ryan T
authors.initials: RT
authors.lastname: Ranallo
authors.forename: Arvind A
authors.initials: AA
authors.lastname: Bhagwat
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D018938:Caco-2 Cells / Q000382:microbiology; D002460:Cell Line / Q000382:microbiology; D006224:Cricetinae; D005455:Fluorescent Antibody Technique; D005936:Glucans / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells / Q000382:microbiology; D006801:Humans; D008264:Macrophages / Q000382:microbiology; D051379:Mice; D008856:Microscopy, Fluorescence; D009154:Mutation; D009994:Osmolar Concentration; D019897:Periplasm / Q000235:genetics / Q000378:metabolism*; D012763:Shigella flexneri / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D005936:Glucans