Evidence for energy-dependent transposition of core lipopolysaccharide across the inner membrane of Salmonella typhimurium.

AUTOR(ES)

McGrath, B C

RESUMO

The uncoupler 2,4-dinitrophenol blocks the final step of lipopolysaccharide assembly--transfer of O antigen from undecaprenyl pyrophosphate to core lipopolysaccharide--in intact Salmonella typhimurium but not in isolated membrane fractions. The O-antigen ligase enzyme is not inhibited by dinitrophenol in vitro, and core lipopolysaccharide synthesized in the presence of uncoupler in vivo is functional as acceptor of O antigen in vitro. The evidence strongly suggests that maintenance of proton motive force is required for transmembrane transposition of core lipopolysaccharide to the active site of O-antigen ligase at the periplasmic face of the inner membrane.

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