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Apocytochrome c requires the TOM complex for translocation across the mitochondrial outer membrane
Author(s) -
Diekert Kerstin,
de Kroon Anton I.P.M.,
Ahting Uwe,
Niggemeyer Brigitte,
Neupert Walter,
de Kruijff Ben,
Lill Roland
Publication year - 2001
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/20.20.5626
Subject(s) - intermembrane space , biology , translocase , mitochondrial intermembrane space , translocase of the inner membrane , microbiology and biotechnology , translocase of the outer membrane , inner membrane , bacterial outer membrane , inner mitochondrial membrane , mitochondrion , biochemistry , chromosomal translocation , mitochondrial membrane transport protein , gene , escherichia coli
The import of proteins into the mitochondrial intermembrane space differs in various aspects from the classical import pathway into the matrix. Apocytochrome c defines one of several pathways known to reach the intermembrane space, yet the components and pathways involved in outer membrane translocation are poorly defined. Here, we report the reconstitution of the apocytochrome c import reaction using proteoliposomes harbouring purified components. Import specifically requires the protease‐resistant part of the TOM complex and is driven by interactions of the apoprotein with internal parts of the complex (involving Tom40) and the ‘ trans ‐side receptor’ cytochrome c haem lyase. Despite the necessity of TOM complex function, the translocation pathway of apocytochrome c does not overlap with that of presequence‐containing preproteins. We conclude that the TOM complex is a universal preprotein translocase that mediates membrane passage of apocytochrome c and other preproteins along distinct pathways. Apocytochrome c may provide a paradigm for the import of other small proteins into the intermembrane space such as factors used in apoptosis and protection from stress.