Arrangement of the respiratory chain complexes in Saccharomyces cerevisiae supercomplex III2IV2 revealed by single particle cryo-electron microscopy

J Biol Chem. 2012 Jun 29;287(27):23095-103. doi: 10.1074/jbc.M112.367888. Epub 2012 May 9.

Abstract

Here we present for the first time a three-dimensional cryo-EM map of the Saccharomyces cerevisiae respiratory supercomplex composed of dimeric complex III flanked on each side by one monomeric complex IV. A precise fit of the existing atomic x-ray structures of complex III from yeast and complex IV from bovine heart into the cryo-EM map resulted in a pseudo-atomic model of the three-dimensional structure for the supercomplex. The distance between cytochrome c binding sites of complexes III and IV is about 6 nm, which supports proposed channeling of cytochrome c between the individual complexes. The opposing surfaces of complexes III and IV differ considerably from those reported for the bovine heart supercomplex as determined by cryo-EM. A closer association between the individual complex domains at the aqueous membrane interface and larger spaces between the membrane-embedded domains where lipid molecules may reside are also demonstrated. The supercomplex contains about 50 molecules of cardiolipin (CL) with a fatty acid composition identical to that of the inner membrane CL pool, consistent with CL-dependent stabilization of the supercomplex.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cryoelectron Microscopy / methods*
  • Crystallography, X-Ray
  • Electron Transport / physiology
  • Electron Transport Complex III / chemistry*
  • Electron Transport Complex III / isolation & purification
  • Electron Transport Complex III / metabolism
  • Electron Transport Complex IV / chemistry*
  • Electron Transport Complex IV / isolation & purification
  • Electron Transport Complex IV / metabolism
  • Lipids / chemistry
  • Mitochondria / enzymology*
  • Mitochondria / ultrastructure
  • Models, Chemical
  • Protein Structure, Quaternary
  • Protein Structure, Tertiary
  • Saccharomyces cerevisiae / enzymology*
  • Saccharomyces cerevisiae / ultrastructure
  • Saccharomyces cerevisiae Proteins / chemistry*
  • Saccharomyces cerevisiae Proteins / isolation & purification
  • Saccharomyces cerevisiae Proteins / metabolism
  • Species Specificity
  • Structure-Activity Relationship

Substances

  • Lipids
  • Saccharomyces cerevisiae Proteins
  • Electron Transport Complex IV
  • Electron Transport Complex III