Abstract
In the past three decades, significant advances have been made in providing the biochemical background of TOM (translocase of the outer mitochondrial membrane)-mediated protein translocation into mitochondria. In the light of recent cryoelectron microscopy-derived structures of TOM isolated from Neurospora crassa and Saccharomyces cerevisiae, the interpretation of biochemical and biophysical studies of TOM-mediated protein transport into mitochondria now rests on a solid basis. In this review, we compare the subnanometer structure of N. crassa TOM core complex with that of yeast. Both structures reveal remarkably well-conserved symmetrical dimers of 10 membrane protein subunits. The structural data also validate predictions of weakly stable regions in the transmembrane β-barrel domains of the protein-conducting subunit Tom40, which signal the existence of β-strands located in interfaces of protein-protein interactions.
Acknowledgements
This article is dedicated to Walter Neupert who had been the director of the TOM project at Munich University and had always inspired those working with him by his ideas and passionate attitude. The authors of this review thank the colleagues who contributed to the research and shared their experience in the journey toward the elucidation of the TOM structure with them, in particular Werner Kühlbrandt (Max-Planck-Institute of Biophysics, Frankfurt). S.N. also wants to thank Robin Gosh (University of Stuttgart) for many helpful discussions. This work was supported by the Max Planck Society (T.B.) and the University of Stuttgart (S.N.).
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Supplementary Material
The online version of this article offers supplementary material (https://doi.org/10.1515/hsz-2020-0104).
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