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  • The EMBO Journal (2000) 19, 542 - 549
  • doi:10.1093/emboj/19.4.542

YidC, the Escherichia coli homologue of mitochondrial Oxa1p, is a component of the Sec translocase

Pier A. Scotti1,5, Malene L. Urbanus1,5, Josef Brunner2, Jan-Willem L. de Gier3, Gunnar von Heijne3, Chris van der Does4, Arnold J.M. Driessen4, Bauke Oudega1 and Joen Luirink1

  1. Department of Microbiology, Institute of Molecular Biological Sciences, Biocentrum Amsterdam, De Boelelaan 1087, 1081 HV Amsterdam, The Netherlands
  2. Institute of Biochemistry, Swiss Federal Institute of Technology (ETH) Zürich, ETH-Center, CH-8092 Zürich, Switzerland
  3. Department of Biochemistry, Stockholm University, S-106 91 Stockholm, Sweden
  4. Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands
  5. P.A.Scotti and M.L.Urbanus contributed equally to this work

Correspondence to:

Joen Luirink, E-mail: luirink@bio.vu.nl

Received 24 September 1999; Accepted 10 December 1999; Revised 30 November 1999

In Escherichia coli, both secretory and inner membrane proteins initially are targeted to the core SecYEG inner membrane translocase. Previous work has also identified the peripherally associated SecA protein as well as the SecD, SecF and YajC inner membrane proteins as components of the translocase. Here, we use a cross-linking approach to show that hydrophilic portions of a co-translationally targeted inner membrane protein (FtsQ) are close to SecA and SecY, suggesting that insertion takes place at the SecA/Y interface. The hydrophobic FtsQ signal anchor sequence contacts both lipids and a novel 60 kDa translocase-associated component that we identify as YidC. YidC is homologous to Saccharomyces cerevisiae Oxa1p, which has been shown to function in a novel export pathway at the mitochondrial inner membrane. We propose that YidC is involved in the insertion of hydrophobic sequences into the lipid bilayer after initial recognition by the SecAYEG translocase.

  • Keywords:

    • membrane protein,
    • Oxa1p,
    • SRP,
    • targeting,
    • translocase