The c subunits of F0F1‐ATP synthase (F0c) assemble into a ring structure, following membrane insertion that is dependent on both glycolipid MPIase and protein YidC. We analyzed the insertion and assembly processes of Propionigenium modestum F0c (Pm‐F0c), of which the ring structure is resistant to SDS. Ring assembly of Pm‐F0c requires P. modestum UncI (Pm‐UncI). Ring assembly of in vitro synthesized Pm‐F0c was observed when both YidC and Pm‐UncI were reconstituted into liposomes of Escherichia coli phospholipids. Under the physiological conditions where spontaneous insertion had been blocked by diacylglycerol, MPIase was necessary for Pm‐F0c insertion allowing the subsequent YidC/Pm‐UncI‐dependent ring assembly. Thus, we have succeeded in the complete reconstitution of membrane insertion and subsequent ring assembly of Pm‐F0c.

From these results, we conclude that the biosynthetic genes for MPIase and ECA are independent.