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Assembly of the three small Tim proteins precedes docking to the mitochondrial carrier translocase
Author(s) -
Gebert Natalia,
Chacinska Agnieszka,
Wagner Karina,
Guiard Bernard,
Koehler Carla M,
Rehling Peter,
Pfanner Nikolaus,
Wiedemann Nils
Publication year - 2008
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.1038/embor.2008.49
Subject(s) - translocase , atp–adp translocase , mitochondrial carrier , docking (animal) , mitochondrion , biophysics , microbiology and biotechnology , biology , chemistry , inner mitochondrial membrane , genetics , chromosomal translocation , bacterial outer membrane , gene , medicine , escherichia coli , nursing
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.