Structural Basis for Protein Translocation by the Translocase of the Outer Mitochondrial Membrane

Abstract

The TOM complex is the main entry gate for mitochondrial proteins. Recently we determined the Cryo-EM structure of the yeast TOM complex at 3.8 Å resolution. The structure shows the dimeric form consisting of two Tom40 β-barrel channels and α-helical transmembrane subunits. The structure-based biochemical analysis revealed that presequence-containing preproteins pass through the Tom40 channel in the middle of the dimer and are transferred to the TIM23 complex. On the other hand, presequence-less preproteins leave the channel at the periphery of the TOM complex and are relayed to the chaperone proteins. Our results demonstrate the efficient transfer mechanism of preproteins.