Biogenesis of yeast mitochondrial cytochrome c: a unique relationship to the TOM machinery

J Mol Biol. 2003 Mar 21;327(2):465-74. doi: 10.1016/s0022-2836(03)00118-9.

Abstract

The import of cytochrome c into the mitochondrial intermembrane space is not understood at a mechanistic level. While the precursor apocytochrome c can insert into protein-free lipid bilayers, the purified translocase of the outer membrane (TOM) complex supports the translocation of apocytochrome c into proteoliposomes. We report an in organello analysis of cytochrome c import into yeast mitochondria from wild-type cells and different mutants cells, each defective in one of the seven Tom proteins. The import of cytochrome c is not affected by removal of the receptor Tom20 or Tom70. Moreover, neither the transfer protein Tom5 nor the assembly factors Tom6 and Tom7 are needed for import of cytochrome c. When the general import pore (GIP)-protein Tom40 is blocked, the import of cytochrome c is moderately affected. Mitochondria lacking the central receptor and organizing protein Tom22 contain greatly reduced levels of cytochrome c. We conclude that up to two components of the TOM complex, Tom22 and possibly the GIP, are involved in the biogenesis of cytochrome c.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cytochrome c Group / metabolism*
  • Membrane Transport Proteins / genetics
  • Membrane Transport Proteins / physiology*
  • Mitochondria / enzymology*
  • Organelle Biogenesis
  • Protein Transport
  • Saccharomyces cerevisiae / enzymology*
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / physiology*

Substances

  • Cytochrome c Group
  • Membrane Transport Proteins
  • Saccharomyces cerevisiae Proteins