Molecular architecture of the active mitochondrial protein gate.

Science (New York, N.Y.) 2015 Sep 25

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Mitochondria fulfill central functions in cellular energetics, metabolism, and signaling. The outer membrane translocator complex (the TOM complex) imports most mitochondrial proteins, but its architecture is unknown. Using a cross-linking approach, we mapped the active translocator down to single amino acid residues, revealing different transport paths for preproteins through the Tom40 channel. An N-terminal segment of Tom40 passes from the cytosol through the channel to recruit chaperones from the intermembrane space that guide the transfer of hydrophobic preproteins. The translocator contains three Tom40 β-barrel channels sandwiched between a central α-helical Tom22 receptor cluster and external regulatory Tom proteins. The preprotein-translocating trimeric complex exchanges with a dimeric isoform to assemble new TOM complexes. Dynamic coupling of α-helical receptors, β-barrel channels, and chaperones generates a versatile machinery that transports about 1000 different proteins. Copyright © 2015, American Association for the Advancement of Science.

Citation

Takuya Shiota, Kenichiro Imai, Jian Qiu, Victoria L Hewitt, Khershing Tan, Hsin-Hui Shen, Noriyuki Sakiyama, Yoshinori Fukasawa, Sikander Hayat, Megumi Kamiya, Arne Elofsson, Kentaro Tomii, Paul Horton, Nils Wiedemann, Nikolaus Pfanner, Trevor Lithgow, Toshiya Endo. Molecular architecture of the active mitochondrial protein gate. Science (New York, N.Y.). 2015 Sep 25;349(6255):1544-8