The purified E. coli integral membrane protein SecY/E is sufficient for reconstitution of SecA-dependent precursor protein translocation.
We have previously reconstituted the soluble phase of precursor protein translocation in vitro using purified proteins (the precursor proOmpA, the chaperone SecB, and the ATPase SecA) in addition to isolated inner membrane vesicles. We now report the isolation of the SecY/E protein, the integral membrane protein component of the E. coli preprotein translocase. The SecY/E protein, reconstituted into proteoliposomes, acts together with SecA protein to support translocation of proOmpA, the precursor form of outer membrane protein A. This translocation requires ATP and is strongly stimulated by the protonmotive force. The initial rates and the extents of translocation into either native membrane vesicles or proteoliposomes with pure SecY/E are comparable. The SecY/E protein consists of SecY, SecE, and an additional polypeptide. Antiserum against SecY immunoprecipitates all three components of the SecY/E protein.
Brundage
L
L
Molecular Biology Institute, University of California, Los Angeles 90024-1570.
Hendrick
J P
JP
Schiebel
E
E
Driessen
A J
AJ
Wickner
W
W
D000251:Adenosine Triphosphatases / Q000378:metabolism; D001426:Bacterial Proteins / Q000302:isolation & purification / Q000378:metabolism*; D001693:Biological Transport, Active; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D006863:Hydrogen-Ion Concentration; D046911:Macromolecular Substances; D008564:Membrane Potentials; D008565:Membrane Proteins / Q000302:isolation & purification / Q000378:metabolism*; D008970:Molecular Weight; D011498:Protein Precursors / Q000378:metabolism*; D000069816:SEC Translocation Channels
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D046911:Macromolecular Substances; D008565:Membrane Proteins; D011498:Protein Precursors; D000069816:SEC Translocation Channels; C065493:SecE protein, E coli; C057841:SecY protein, E coli; D000251:Adenosine Triphosphatases