A YidC-like Protein in the Archaeal Plasma Membrane

• Published in: Structure (London) 2015-09, Vol.23 (9), p.1715-1724
• Main Authors: Borowska, Marta T., Dominik, Pawel K., Anghel, S. Andrei, Kossiakoff, Anthony A., Keenan, Robert J.
• Format: Article
• Language: English
• Subjects: Archaeal Proteins - chemistry; Archaeal Proteins - metabolism; Cell Membrane - metabolism; Membrane Transport Proteins - chemistry; Membrane Transport Proteins - metabolism; Methanocaldococcus - chemistry; Methanocaldococcus - metabolism; Models, Molecular; Phylogeny; Protein Structure, Secondary; Ribosomes - metabolism
• ISSN: 0969-2126; 1878-4186; 1878-4186
• DOI: 10.1016/j.str.2015.06.025

Cells possess specialized machinery to direct the insertion of membrane proteins into the lipid bilayer. In bacteria, the essential protein YidC inserts certain proteins into the plasma membrane, and eukaryotic orthologs are present in the mitochondrial inner membrane and the chloroplast thylakoid membrane. The existence of homologous insertases in archaea has been proposed based on phylogenetic analysis. However, limited sequence identity, distinct architecture, and the absence of experimental data have made this assignment ambiguous. Here we describe the 3.5-Å crystal structure of an archaeal DUF106 protein from Methanocaldococcus jannaschii (Mj0480), revealing a lipid-exposed hydrophilic surface presented by a conserved YidC-like fold. Functional analysis reveals selective binding of Mj0480 to ribosomes displaying a stalled YidC substrate, and a direct interaction between the buried hydrophilic surface of Mj0480 and the nascent chain. These data provide direct experimental evidence that the archaeal DUF106 proteins are YidC/Oxa1/Alb3-like insertases of the archaeal plasma membrane. [Display omitted] •An archaeal DUF106 protein from M. jannaschii (Mj0480) adopts a YidC-like fold•Mj0480 binds selectively to stalled ribosome-nascent chain complexes•The nascent chain directly contacts a lipid-exposed hydrophilic surface of Mj0480•This work establishes the universality of YidC proteins in all three domains of life YidC/Oxa1/Alb3 proteins are essential for the insertion of certain membrane proteins in bacteria and eukaryotes. Borowska et al. now describe an archaeal protein with structural and functional similarities to bacterial YidC. This work establishes the universality of the YidC/Oxa1/Alb3 family in the three domains of life.