Escherichia coli YidC is a membrane insertase for Sec-independent proteins

Abstract

YidC is a recently discovered bacterial membrane protein that is related to the mitochondrial Oxa1p and the Alb3 protein of chloroplasts. These proteins are required in the membrane integration process of newly synthesized proteins that do not require the classical Sec machinery. Here we demonstrate that YidC is sufficient for the membrane integration of a Sec-independent protein. Microgram amounts of the purified single-spanning Pf3 coat protein were efficiently inserted into proteoliposomes containing the purified YidC. A mutant Pf3 coat protein with an extended hydrophobic region was inserted independently of YidC into the membrane both in vivo and in vitro, but its insertion was accelerated by YidC. These results show that YidC can function separately from the Sec translocase to integrate membrane proteins into the lipid bilayer.

Efficient Assembly of Photosystem II in Chlamydomonas reinhardtii Requires Alb3.1p, a Homolog of Arabidopsis ALBINO3

“…This protein is the homolog of mitochondrial Oxa1p and of bacterial YidC, which have been described as integrases involved in the translocation and/or integration of membrane proteins (Moore et al, 2000(Moore et al, , 2003Kuhn et al, 2003). Nevertheless, it was reported that the integral membrane Cox3p and Pf3 coat protein integrate into membranes independently from Oxa1p and YidC, respectively, although with a lower integration efficiency (Hell et al, 2001;Serek et al, 2004).…”

Lipoprotein biogenesis in Gram-positive bacteria: knowing when to hold ‘em, knowing when to fold ‘em

“…Several Gram-positive members of the membrane insertase YidC family [75] are putative lipoproteins and there are numerous peptidyl-prolyl isomerase (PPIase; also termed foldase or maturase) lipoproteins in Gram-positive bacteria including the essential PrsA in B. subtilis [76] and FkbA in Streptomyces anulatus (formerly Streptomyces chrysomallus) [77] that most likely accelerate protein folding …”

Altered Escherichia coli membrane protein assembly machinery allows proper membrane assembly of eukaryotic protein vitamin K epoxide reductase

“…Although the majority of inner membrane proteins tested require SecYEG for assembly, fewer are dependent on YidC for integration into the membrane (8). Nevertheless, both integration machineries are essential for E. coli viability.…”