title: SecA protein needs both acidic phospholipids and SecY/E protein for functional high-affinity binding to the Escherichia coli plasma membrane.
abstract: Translocation of preproteins across the Escherichia coli inner membrane requires acidic phospholipids. We have studied the translocation of the precursor protein proOmpA across inverted inner membrane vesicles prepared from cells depleted of phosphatidylglycerol and cardiolipin. These membranes support neither translocation nor the translocation ATPase activity of the SecA subunit of preprotein translocase. We now report that inner membrane vesicles which are depleted of acidic phospholipids are unable to bind SecA protein with high affinity. These membranes can be restored to translocation competence by fusion with liposomes containing phosphatidylglycerol, suggesting that the defect in SecA binding is a direct effect of phospholipid depletion rather than a general derangement of inner membrane structure. Reconstitution of SecY/E, the membrane-embedded domain of translocase, into proteoliposomes containing predominantly a single synthetic acidic lipid, dioleoylphosphatidylglycerol, allows efficient catalysis of preprotein translocation.
authors.affiliation: Molecular Biology Institute, University of California, Los Angeles 90024-1570.
authors.forename: J P
authors.initials: JP
authors.lastname: Hendrick
authors.forename: W
authors.initials: W
authors.lastname: Wickner
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism*; D001692:Biological Transport; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000201:enzymology / Q000378:metabolism*; D029968:Escherichia coli Proteins; D006863:Hydrogen-Ion Concentration; D008565:Membrane Proteins / Q000378:metabolism*; D026901:Membrane Transport Proteins; D010743:Phospholipids / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism; D011510:Proteolipids / Q000378:metabolism; D000069816:SEC Translocation Channels; D000081416:SecA Proteins
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D010743:Phospholipids; D011498:Protein Precursors; D011510:Proteolipids; D000069816:SEC Translocation Channels; C057184:outer membrane protein A precursor (E coli); C020485:proteoliposomes; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins