Preprotein translocation creates a halide anion permeability in the Escherichia coli plasma membrane.
The electrochemical potential drives the translocation of the precursor form of outer membrane protein A (proOmpA) and other proteins across the plasma membrane of Escherichia coli. We have measured the electrical potential, delta psi, across inverted membrane vesicles during proOmpA translocation. delta psi, generated by the electron transport chain, is substantially dissipated by proOmpA translocation. delta psi dissipation requires SecA, ATP, and proOmpA. proOmpA which, due to the covalent addition of a folded protein to a cysteinyl side chain, is arrested during its translocation, can nevertheless cause the loss of delta psi. Thus the movement of charged amino acyl residues is not dissipating the potential. This translocation-specific reduction in delta psi is only seen in the presence of halide anions, although halide anions are not needed for proOmpA translocation per se. We therefore propose that translocation intermediates directly increase the membrane permeability to halide anions.
Schiebel
E
E
Molecular Biology Institute, University of California, Los Angeles 90024-1570.
Wickner
W
W
D000838:Anions; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism*; D001692:Biological Transport; D002463:Cell Membrane Permeability; D004563:Electrochemistry; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D006219:Halogens / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D009097:Multienzyme Complexes / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D011498:Protein Precursors / Q000378:metabolism*; D021382:Protein Sorting Signals / Q000378:metabolism
D000838:Anions; D001425:Bacterial Outer Membrane Proteins; D029968:Escherichia coli Proteins; D006219:Halogens; D009097:Multienzyme Complexes; D011498:Protein Precursors; D021382:Protein Sorting Signals; C057184:outer membrane protein A precursor (E coli); C023107:NADH oxidase; D009247:NADH, NADPH Oxidoreductases