Function of YidC for the Insertion of M13 Procoat Protein inEscherichia coli

Abstract

The membrane insertion of the Sec-independent M13 Procoat protein in bacteria requires the membrane electrochemical potential and the integral membrane protein YidC. We show here that YidC is involved in the translocation but not in the targeting of the Procoat protein, because we found the protein was partitioned into the membrane in the absence of YidC. YidC can function also to promote membrane insertion of Procoat mutants that insert independently of the membrane potential, proving that the effect of YidC depletion is not due to a dissipation of the membrane potential. We also found that YidC is absolutely required for Sec-dependent translocation of a long periplasmic loop of a mutant Procoat in which the periplasmic region has been extended from 20 to 194 residues. Furthermore, when Secdependent membrane proteins with large periplasmic domains were overproduced under YidC-limited conditions, we found that the exported proteins pro-OmpA and pre-peptidoglycan-associated lipoprotein accumulated in the cytoplasm. This suggests for Sec-dependent proteins that YidC functions at a late stage in membrane insertion, after the Sec translocase interacts with the translocating membrane protein. These studies are consistent with the understanding that YidC cooperates with the Sec translocase for membrane translocation and that YidC is required for clearing the protein-conducting channel.

SecYEG Proteoliposomes Catalyze the Δϕ-Dependent Membrane Insertion of FtsQ

“…On the basis of cross-linking studies, it has been suggested that YidC interacts with nascent TMS, whereas a YidC defect in vivo seems to cause a pleiotropic effect on protein translocation, probably because of jamming of the translocase (14,42,43). It has been postulated that YidC catalyzes the lateral transfer of TMS from the translocase into the lipid bilayer.…”

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

“…These proteins are believed to serve as membrane-localized chaperones involved in translocation and assembly of a large number of membrane proteins (23,24) and function in concert with the Sec translocon (23,25,26), as well as independently (27,28). Recently, Oxa2 was identified in mitochondria of Neurospora crassa and functionally complemented the related yeast protein Cox18 (29).…”

Role of the Cytosolic Loop C2 and the C Terminus of YidC in Ribosome Binding and Insertion Activity

“…Escherichia coli YidC is an abundant membrane protein, with ϳ2500 copies per cell (1) and it is involved in the insertion, folding and/or assembly of membrane proteins into the cytoplasmic membrane independently or in concert with the SecYEG translocon (4). E. coli YidC is essential for cell viability (5) and has been shown to function as an insertase in the membrane insertion of the filamentous phage Pf3 coat and M13 pro-coat proteins (5,6) and the endogenous substrates F 0 c (7), MscL (8,9), and TssL (10). In cooperation with the Sec translocase, YidC assists in the membrane insertion of CyoA (11,12), NuoK (13), and F 0 a and F 0 b subunits of F 1 F 0 ATPase (14), and the translocation of the periplasmic loop 1 and loop 2 of TatC (15).…”