SecYEG proteoliposomes catalyze the Deltaphi-dependent membrane insertion of FtsQ
Martin van der Laan1, Nico Nouwen, Arnold J M Driessen
1Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands.
Abstract:
In Escherichia coli, the insertion of most inner membrane proteins is mediated by the Sec translocase. Ribosome-bound nascent chains of Sec-dependent inner membrane proteins are targeted to the SecYEG complex via the signal recognition particle pathway. We now demonstrate that the signal recognition particle-dependent co-translational membrane targeting and membrane insertion of FtsQ can be reconstituted with proteoliposomes containing purified SecYEG. SecA and a transmembrane electrical potential are essential for the translocation of the large periplasmic domain of FtsQ, whereas co-reconstituted YidC has an inhibitory effect. These data demonstrate that membrane protein insertion can be reconstituted with a minimal set of purified Sec components.
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