The TOM complex is the main entry point for precursor proteins into mitochondria. This manuscript describes the structure of the TOM core complex from Neurospora crassa determined by single-particle cryoEM at 3.3 Angstrom resolution, the interaction with a bound presequence at 4 Angstrom resolution, and the structure of the TOM holo complex including the Tom20 receptor at 6-7 Angstrom resolution. We propose that Tom20 acts as a dynamic gatekeeper, guiding precursor proteins into the pores of the TOM complex. The interactions of Tom20 with other TOM subunits present insights into the structure of the TOM holo complex, and suggest a translocation mechanism.
For reference, see Two conformations of the Tom20 preprotein receptor in the TOM holo complex. Ornelas, P., Bausewein, T., Martin, J., Morgner, N., Nussberger, S. & Kühlbrandt, W. bioRxiv, doi: 10.1101/2023.01.26.525638 preprint (2023)