The mitochondrial intermembrane space contains a family of small Tim proteins that function as essential chaperones for protein import. The soluble Tim9-Tim10 complex transfers hydrophobic precursor proteins through the aqueous intermembrane space to the carrier translocase of the inner membrane (TIM22 complex). Tim12, a peripheral membrane subunit of the TIM22 complex, is thought to recruit a portion of Tim9-Tim10 to the inner membrane. It is not known, however, how Tim12 is assembled. We have identified a new intermediate in the biogenesis pathway of Tim12. A soluble form of Tim12 first assembles with Tim9 and Tim10 to form a Tim12-core complex. Tim12-core then docks onto the membrane-integrated subunits of the TIM22 complex to form the holo-translocase. Thus, the function of Tim12 in linking soluble and membrane-integrated subunits of the import machinery involves a sequential assembly mechanism of the translocase through a soluble intermediate complex of the three essential small Tim proteins.

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Reference Type

Journal Article | Research Support, Non-U.S. Gov't

Authors

Gebert N, Chacinska A, Wagner K, Guiard B, Koehler CM, Rehling P, Pfanner N, Wiedemann N

Primary Lit For

Additional Lit For

TIM12 | TIM22 | TIM54 | TIM9 | TIM10 | TIM18 | MIA40 | TIM9-TIM10 mitochondrial intermembrane space protein transporter complex | TIM9-TIM10-TIM12 mitochondrial intermembrane space protein transporter complex

Review For