title: SecA protein is exposed to the periplasmic surface of the E. coli inner membrane in its active state.
abstract: E. coli cells harboring pCG169 containing the secD secF locus possessed SecA protein almost entirely in an integral membrane form in which it displayed normal protein translocation activity. These results imply that integral membrane SecA is the catalytically active form of this enzyme and that products of the secD secF locus regulate SecA association with the inner membrane. Protease and biotinylation accessibility studies of right side-out and inside-out membrane vesicles derived from this strain revealed that SecA was exposed to the periplasmic surface of the inner membrane. These studies suggest a model of bacterial protein secretion, whereby insertion of SecA into the inner membrane and its association with SecY/E/G promotes assembly of active protein-conducting channels comprised in part of integral membrane SecA protein, and products of the secD secF locus regulate the channel assembly-disassembly reaction by modulating the SecA insertion-deinsertion step.
authors.affiliation: Department of Molecular Biology and Biochemistry, Wesleyan University, Middletown, Connecticut 06459.
authors.forename: Y J
authors.initials: YJ
authors.lastname: Kim
authors.forename: T
authors.initials: T
authors.lastname: Rajapandi
authors.forename: D
authors.initials: D
authors.lastname: Oliver
mesh_terms: D000251:Adenosine Triphosphatases / Q000187:drug effects / Q000378:metabolism*; D001426:Bacterial Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D001710:Biotin; D002451:Cell Compartmentation; D002462:Cell Membrane / Q000378:metabolism*; D016764:Cell Polarity; D010450:Endopeptidases / Q000494:pharmacology; D004926:Escherichia coli / Q000502:physiology*; D029968:Escherichia coli Proteins; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D026901:Membrane Transport Proteins; D015335:Molecular Probes; D000069816:SEC Translocation Channels; D000081416:SecA Proteins
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D015335:Molecular Probes; D000069816:SEC Translocation Channels; C499394:SecD protein, E coli; C489583:SecF protein, E coli; C075767:secD protein, Bacteria; C075768:secF protein, Bacteria; D001710:Biotin; D010450:Endopeptidases; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins