title: Role for membrane potential in the secretion of protein into the periplasm of Escherichia coli.
abstract: The leucine-specific binding protein of Escherichia coli is a periplasmic protein that is synthesized as a precursor and subsequently is processed during its secretion into the periplasmic space. The processing of both the leucine-specific binding protein and a plasmid-coded beta-lactamase is inhibited by phenethyl alcohol and by the proton ionophore, carbonylcyanide m-chlorophenylhydrazone (CCCP). The levels of CCCP that inhibit processing also produce significant decreases in the membrane potential. Valinomycin, a potassium ionophore, also inhibits processing of the leucine-specific binding protein in spheroplasts. Processing can be restored in CCCP-treated cells and in valinomycin-treated spheroplasts by dilution of the treated cells in fresh medium. These results suggest a role for membrane potential in the secretion of periplasmic proteins. A model is presented which suggests that membrane potential plays a primary role in the proper orientation of the precursor signal sequence within the membrane, thus promoting processing and secretion.
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D002352:Carrier Proteins / Q000378:metabolism; D004926:Escherichia coli / Q000502:physiology*; D029968:Escherichia coli Proteins; D008564:Membrane Potentials / Q000187:drug effects; D008954:Models, Biological; D033902:Periplasmic Binding Proteins; D011189:Potassium Chloride / Q000494:pharmacology; D011498:Protein Precursors / Q000378:metabolism; D014634:Valinomycin / Q000378:metabolism; D001618:beta-Lactamases / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; C024913:LivK protein, E coli; D033902:Periplasmic Binding Proteins; D011498:Protein Precursors; D014634:Valinomycin; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D011189:Potassium Chloride; D001618:beta-Lactamases