Reconstitution of Sec-dependent membrane protein insertion: nascent FtsQ interacts with YidC in a SecYEG-dependent manner

The inner membrane protein YidC is associated with the preprotein transloca se of Escherichia coli and contacts transmembrane segments of nascent inner membrane proteins during membrane insertion. YidC was purified to homogene ity and co-reconstituted with the SecYEG complex. YidC had no effect on the SecA/SecYEG-mediated translocation of the secretory protein proOmpA; howev er, using a crosslinking approach, the transmembrane segment of nascent Fts Q was found to gain access to YidC via SecY. These data indicate the functi onal reconstitution of the initial stages of YidC-dependent membrane protei n insertion via the SecYEG complex.