title: Energy dependence of O-antigen synthesis in Salmonella typhimurium.
abstract: The uncoupler 2,4-dinitrophenol prevents in vivo synthesis of O antigen in Salmonella typhimurium by inhibiting the first reaction of the pathway, formation of galactosyl-pyrophosphoryl-undecaprenol. Inhibition was observed only in intact cells; dinitrophenol had no effect on activity of the synthase enzyme in isolated membrane fractions. In vivo inhibition could not be explained by changes in intracellular nucleotide pools or a shift in the equilibrium of the reaction and appeared to be specific for the first step in the pathway. Neither the subsequent mannosyl transferase, which catalyzes formation of the trisaccharide-lipid intermediate, mannosyl-rhamnosyl-galactosyl-pyrophosphoryl-undecaprenol, nor O-antigen polymerase was inhibited. In addition, incorporation of galactose into core lipopolysaccharide was only modestly inhibited under conditions in which O-antigen synthesis was abolished. The results suggest that maintenance of proton motive force is required for access of substrate, UDP-galactose and/or undecaprenyl phosphate, to the active site of the galactosyl-pyrophosphoryl-undecaprenol synthase enzyme.
authors.affiliation: Department of Microbiology, University of Connecticut Health Center, Farmington 06030.
authors.forename: P A
authors.initials: PA
authors.lastname: Marino
authors.forename: B C
authors.initials: BC
authors.lastname: McGrath
authors.forename: M J
authors.initials: MJ
authors.lastname: Osborn
mesh_terms: D000942:Antigens, Bacterial / Q000096:biosynthesis*; D001693:Biological Transport, Active; D004140:Dinitrophenols / Q000494:pharmacology; D004734:Energy Metabolism; D005690:Galactose / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008070:Lipopolysaccharides / Q000378:metabolism; D008358:Mannose / Q000378:metabolism; D008564:Membrane Potentials; D019081:O Antigens; D009844:Oligosaccharides / Q000378:metabolism; D010766:Phosphorylation; D012486:Salmonella typhimurium / Q000276:immunology / Q000378:metabolism*; D013729:Terpenes / Q000378:metabolism; D014542:Uridine Monophosphate / Q000378:metabolism
chemical_list: D000942:Antigens, Bacterial; D004140:Dinitrophenols; D008070:Lipopolysaccharides; D019081:O Antigens; D009844:Oligosaccharides; D013729:Terpenes; C017788:undecaprenol; D014542:Uridine Monophosphate; D008358:Mannose; D005690:Galactose