Mechanistic insights into fungal mitochondrial outer membrane protein biogenesis

• Published in: Current opinion in structural biology 2022-06, Vol.74, p.102383-102383, Article 102383
• Main Authors: Diederichs, Kathryn A., Pitt, Ashley S., Varughese, Joyce T., Hackel, Taylor N., Buchanan, Susan K., Shaw, Porsha L.
• Format: Article
• Language: English
• Subjects: Mitochondria - metabolism; Mitochondrial Membranes - metabolism; Mitochondrial Precursor Protein Import Complex Proteins; Mitochondrial Proteins; Protein Transport; Saccharomyces cerevisiae Proteins - metabolism
• ISSN: 0959-440X; 1879-033X
• DOI: 10.1016/j.sbi.2022.102383

The majority of mitochondrial proteins are nuclear-encoded and need to be transported into the mitochondria, including the proteins in the outer mitochondrial membrane. For β-barrel proteins, the preproteins are initially recognized and imported by the TOM complex, then shuttled to the SAM complex via small Tim proteins. For ⍺-helical proteins, some preproteins are recognized by the TOM complex and imported into the membrane by the MIM complex. In recent years multiple structures of the TOM complex and the SAM complex have been reported, increasing our understanding of the mechanism of protein biogenesis in the outer mitochondrial membrane. [Display omitted] •Differences in fungal TOM complex structures provide insight on mitochondrial import selection mechanisms.•Fungal SAM complex structures share a similar topology and suggest a β-barrel switching mechanism.•Discussion of MIM complex function and expected structure based on biochemical data to date.•Perspectives on next research steps that will inform mechanistic understanding of outer mitochondrial membrane biogenesis.