YidC Is Strictly Required for Membrane Insertion of Subunits a and c of the F₁F₀ATP Synthase and SecE of the SecYEG Translocase

Abstract

YidC was previously discovered to play a critical role for the insertion of the Sec-independent M13 procoat and Pf3 coat phage proteins into the Escherichia coli inner membrane. To determine whether there is an absolute requirement of YidC for membrane protein insertion of any endogenous E. coli proteins, we investigated a few representative membrane proteins. We found that membrane subunits of the F(0) sector of the F(1)F(0)ATP synthase and the SecE protein of the SecYEG translocase are highly dependent on YidC for membrane insertion, based on protease mapping and immunoblot analysis. We found that the SecE dependency on YidC for membrane insertion does not contradict the observation that depletion of YidC does not block SecYEG-dependent protein export at 37 degrees C. YidC depletion does not decrease the SecE level low enough to block export at 37 degrees C. In contrast, we found that protein export of OmpA is severely blocked at 25 degrees C when YidC is depleted, which may be due to the decreased SecE level, as a 50% decrease in the SecE levels drastically affects protein export at the cold temperature [Schatz, P. J., Bieker, K. L., Ottemann, K. M., Silhavy, T. J., and Beckwith, J. (1991) EMBO J. 10, 1749-57]. These studies reported here establish that physiological substrates of YidC include subunits of the ATP synthase and the SecYEG translocase, demonstrating that YidC plays a vital role for insertion of endogenous membrane proteins in bacteria.

SecYEG Proteoliposomes Catalyze the Δϕ-Dependent Membrane Insertion of FtsQ

“…Various membrane proteins will differ in their YidC dependence and thus in the extent of their interaction with YidC. The recent observation that YidC is required for the biogenesis of F 1 F 0 ATPase and cytochrome o oxidase (30,45) suggests that an essential function of YidC is to mediate membrane insertion and/or assembly of energy-transducing membrane protein complexes.…”

Plastids Contain a Second Sec Translocase System with Essential Functions

“…The cpTat complex assembles in scy1 and alb3 mutants, and biochemical inhibitors of cpTat and SRP were without effect on cpTatC localization. In E. coli, TatC insertion is Sec dependent and likely occurs cotranslationally (Yi et al, 2003). If the mechanism and machinery are conserved in plastids, it is possible that SCY2 acting at the envelope could mediate a pseudo-cotranslational integration of cpTatC, wherein import across Toc and Tic and integration via SCY2 would be coupled.…”

Streptococcal viability and diminished stress tolerance in mutants lacking the signal recognition particle pathway or YidC2

“…The E. coli F 1 F 0 ATP synthase complex consists of a membrane-integral F 0 subunit (protein components a, b, and c) and a membrane-extrinsic F 1 subunit (protein components ␣, ␤, ␥, ␦, and ). The SRP and Sec translocase has been reported to mediate insertion of F 0 a and b components into the membrane (59), and biochemical evidence has indicated a role for YidC in membrane insertion of the F 0 subunit components a and c (60,61). ATP synthase activity is also drastically decreased in the absence of mitochondrial Oxa1 (32).…”