YidC-mediated membrane insertion of assembly mutants of subunit C of the F1F0 ATPase

YidC is a member of the OxaI family of membrane proteins that has been implicated in the membrane insertion of inner membrane proteins in Escherichia coli. We have recently demonstrated that proteoliposomes containing only YidC support both the stable membrane insertion and the oligomerization of the c subunit of the F1F0 ATP synthase (F(0)c). Here we have shown that two mutants of F(0)c unable to form a functional F1F0 ATPase interact with YidC, require YidC for membrane insertion, but fail to oligomerize. These data show that oligomerization is not essential for the stable YidC- dependent membrane insertion of F(0)c consistent with a function of YidC as a membrane protein insertase.