9J9B

Substrate-engaged TIM23 complex from yeast

Summary for 9J9B

• Entry DOI: 10.2210/pdb9j9b/pdb
• EMDB information: 61257
• Descriptor: Mitochondrial import inner membrane translocase subunit TIM17, Mitochondrial import inner membrane translocase subunit TIM23, Mitochondrial import inner membrane translocase subunit TIM44,L-lactate dehydrogenase (cytochrome),sfGFP, ... (8 entities in total)
• Functional Keywords: mitochondrial protein import, tom / tim23 protein translocation, protein transport
• Biological source: Saccharomyces cerevisiae S288C (Baker's yeast); More
• Total number of polymer chains: 7
• Total formula weight: 191118.69

Authors

Yang, Y.Q.,Wang, G.P. (deposition date: 2024-08-22, release date: 2025-09-10, Last modification date: 2026-03-25)

Primary citation

Yang, Y.,Wang, S.,Wang, G.,Lian, Y.,Xue, L.,Jiang, W.,Guo, Q.,Song, C.,Li, L.
Dynamic TOM-TIM23 supercomplex directs mitochondrial protein translocation and sorting.
Nat.Struct.Mol.Biol., 32:2231-2241, 2025

PubMed Abstract: The mitochondrial translocase of the outer membrane (TOM) and translocase of the inner membrane 23 (TIM23) complexes are coupled to control protein import across the outer and inner membranes, respectively. However, the mechanisms of protein recognition and sorting in the TOM-TIM23 pathway remain unclear. Here we report cryo-electron microscopy structures of a translocating polypeptide substrate captured in the active TOM-TIM23 supercomplex from Saccharomyces cerevisiae. In the TOM complex, the polypeptide substrate adopts multiple conformations stabilized by hydrophilic residues from distinct regions of the Tom40 channel. In the TIM23 complex, the Tim17 and Mgr2 subunits create the translocation pathway, with a central restriction formed by four highly conserved hydrophobic residues. The substrate primarily interacts with hydrophobic residues along the Tim17-Mgr2 pathway. Substrate hydrophobicity modulates the association of Mgr2 with Tim17, enabling dynamic regulation of protein sorting toward either the matrix or membrane. These findings reveal a sophisticated translocation mechanism of the TOM-TIM23 supercomplex that ensures the efficient import of diverse mitochondrial proteins.

PubMed: 40877479
DOI: 10.1038/s41594-025-01662-x

Experimental method

ELECTRON MICROSCOPY (3.83 Å)