The charge distribution in the cytoplasmic loop of subunit C of the F 1F0 ATPase is a determinant for YidC targeting

Abstract

YidC is a member of the Oxa1 family of proteins that facilitates the membrane insertion of a subset of inner membrane proteins in Escherichia coli. YidC acts as an insertase for membrane insertion of subunit c of the F 1F0 ATP synthase (F0c), but the requirements for substrate recognition have remained unclear. Here, we have analyzed the role of the charged aminoacyl residues in F0c in YidC targeting and membrane insertion. Binding experiments demonstrate that F0c is targeted directly to YidC without the presence of a stable lipid surface-bound intermediate. Positive charges in the cytoplasmic loop of F0c are important determinants for YidC binding and subsequent membrane insertion. These data support a model in which F0c binds directly to YidC prior to its membrane insertion. © 2008 by The American Society for Biochemistry and Molecular Biology, Inc.