title: SecE-depleted membranes of Escherichia coli are active. SecE is not obligatorily required for the in vitro translocation of certain protein precursors.
abstract: Membrane vesicles were prepared from Escherichia coli cells in which SecE was depleted to 2% of wild-type membranes. SecE depletion had pleiotropic effects; SecD, SecF, SecG, and SecY were decreased 4-6-fold, whereas SecA was increased about 16-fold over that of wild-type membranes. These membranes were substantially active in the in vitro translocation of proOmpA, which was mediated by the SecA pathway since it was inhibited by azide. Similar substantial translocation activities were observed for proLamB and proLpp in the SecE-depleted membranes. However, the translocation of proPhoA was more severely impaired. These data indicate that SecE may enhance but is not obligatorily required for the translocation of at least certain precursors, and suggest that the effects of the SecE depletion on protein translocation may be precursor-dependent.
authors.affiliation: Department of Biology, Georgia State University, Atlanta, Georgia 30303, USA.
authors.forename: Y B
authors.initials: YB
authors.lastname: Yang
authors.forename: N
authors.initials: N
authors.lastname: Yu
authors.forename: P C
authors.initials: PC
authors.lastname: Tai
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism*; D001692:Biological Transport; D002352:Carrier Proteins; D002462:Cell Membrane / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D066298:In Vitro Techniques; D007700:Kinetics; D008074:Lipoproteins; D008565:Membrane Proteins / Q000378:metabolism*; D026901:Membrane Transport Proteins; D011498:Protein Precursors / Q000378:metabolism*; D021382:Protein Sorting Signals; D000069816:SEC Translocation Channels; D000081416:SecA Proteins
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; C085044:LamB signal peptide, E coli; D008074:Lipoproteins; C099932:Lpp protein, E coli; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D011498:Protein Precursors; D021382:Protein Sorting Signals; D000069816:SEC Translocation Channels; C065493:SecE protein, E coli; C057184:outer membrane protein A precursor (E coli); D000251:Adenosine Triphosphatases; D000081416:SecA Proteins