Subunit dynamics in Escherichia coli preprotein translocase

  1. J C Joly,
  2. M R Leonard, and
  3. W T Wickner
  1. Molecular Biology Institute, University of California, Los Angeles 90024-1570.

Abstract

SecY, SecE, and band 1 copurify as the SecY/E integral membrane domain of Escherichia coli preprotein translocase. To measure the in vivo association of these polypeptides and assay possible exchange, plasmid-borne secY and secE genes were placed under control of the ara regulon and fused to DNA encoding the influenza hemagglutinin epitope. Cells were incubated with [35S]methionine, grown for a "chase" period, and then induced with arabinose to express epitope-tagged, nonradioactive SecY and SecE. Both the wild-type and epitope-tagged polypeptides assembled into functional, heterotrimeric SecY/E complex. However, immunoprecipitation with antibody to the epitope tag did not cross-precipitate radiolabeled SecY or SecE. Thus, these subunits normally associate stably in vivo.

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  1. PNAS May 24, 1994 vol. 91 no. 11 4703-4707
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