Isolation and characterization of the TIM10 homologue from the yeast Pichia sorbitophila: a putative component of the mitochondrial protein import system

Abstract

The Saccharomyces cerevisiae TIM10 gene encodes one of the few essential mitochondrial proteins that are required for the import of nuclear-encoded precursor proteins from the cytosol and their subsequent sorting into the different mitochondrial compartments. We have isolated and characterized a putative homologue of TIM10 from the halotolerant yeast Pichia sorbitophila. The Pichia TIM10 gene encodes a protein of 90 amino acids with 66% identity to S. cerevisiae Tim10p. It was capable of suppressing the temperature sensitivity of tim10-1 mutant in S. cerevisiae, suggesting that Pichia TIM10 is both a functional and structural homologue of S. cerevisiae TIM10. The putative Pichia TIM10 gene product contains all the four conserved cysteine residues and the two CX(3)C motifs typical of the Tim family proteins in the mitochondrial intermembrane space. Using anti-Tim10p serum, Western blots detected a protein of about 10 kDa, suggesting that the Pichia Tim10p is a mitochondrial protein. The results suggest that mitochondrial import and sorting systems might be also strongly conserved in other fungi. The coding sequence of the P. sorbitophila TIM10 has been deposited in the EMBL Nucleotide Sequence Database under Accession No. AJ243940.

Reconstituted TOM Core Complex and Tim9/Tim10 Complex of Mitochondria Are Sufficient for Translocation of the ADP/ATP Carrier across Membranes

“…The complex in yeast is a heterohexamer which contains three Tim9 and three Tim10 molecules (Luciano et al, 2001;Curran et al, 2002a;Vial et al, 2002). Although highly conserved homologues of Tim9 and Tim10 were found in the genome of many other eukaryotic organisms (Bauer et al, 1999;Kayingo et al, 2000), the Tim9/Tim10 complex has so far been analyzed only in S. cerevisiae. Two other small Tim components, Tim8 and Tim13, also form a heterohexameric complex in the intermembrane space (Koehler et al, 1999a;Kurz et al, 1999;Leuenberger et al, 1999).…”