Structural insight into mitochondrial β-barrel outer membrane protein biogenesis.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 32620929.
- Also identified by DOI 10.1038/s41467-020-17144-1 and PMC identifier 7335169.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
In mitochondria, β-barrel outer membrane proteins mediate protein import, metabolite transport, lipid transport, and biogenesis. The Sorting and Assembly Machinery (SAM) complex consists of three proteins that assemble as a 1:1:1 complex to fold β-barrel proteins and insert them into the mitochondrial outer membrane. We report cryoEM structures of the SAM complex from Myceliophthora thermophila, which show that Sam50 forms a 16-stranded transmembrane β-barrel with a single polypeptide-transport-associated (POTRA) domain extending into the intermembrane space. Sam35 and Sam37 are located on the cytosolic side of the outer membrane, with Sam35 capping Sam50, and Sam37 interacting extensively with Sam35. Sam35 and Sam37 each adopt a GST-like fold, with no functional, structural, or sequence similarity to their bacterial counterparts. Structural analysis shows how the Sam50 β-barrel opens a lateral gate to accommodate its substrates.
Medical subject headings
- Mitochondria
- Mitochondrial Membrane Transport Proteins
- Mitochondrial Membranes
- Protein Biosynthesis
- Saccharomyces cerevisiae