Dissection of the mitochondrial import and assembly pathway for human Tom40

Abstract

Tom40 is the channel-forming subunit of the translocase of the mitochondrial outer membrane (TOM complex), essential for protein import into mitochondria. Tom40 is synthesized in the cytosol and contains information for its mitochondrial targeting and assembly. A number of stable import intermediates have been identified for Tom40 precursors in fungi, the first being an association with the sorting and assembly machinery (SAM) of the outer membrane. By examining the import pathway of human Tom40, we have been able to elucidate additional features in its import. We identify that Hsp90 is involved in delivery of the Tom40 precursor to mitochondria in an ATP-dependent manner. The precursor then..