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. 1991 May;173(10):3128-33.
doi: 10.1128/jb.173.10.3128-3133.1991.

Energy Dependence of O-antigen Synthesis in Salmonella Typhimurium

Free PMC article

Energy Dependence of O-antigen Synthesis in Salmonella Typhimurium

P A Marino et al. J Bacteriol. .
Free PMC article


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.

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