Extended cardiolipin anchorage to cytochrome c: a model for protein-mitochondrial membrane binding

J Biol Inorg Chem. 2010 Jun;15(5):689-700. doi: 10.1007/s00775-010-0636-z. Epub 2010 Mar 18.

Abstract

Two models have been proposed to explain the interaction of cytochrome c with cardiolipin (CL) vesicles. In one case, an acyl chain of the phospholipid accommodates into a hydrophobic channel of the protein located close the Asn52 residue, whereas the alternative model considers the insertion of the acyl chain in the region of the Met80-containing loop. In an attempt to clarify which proposal offers a more appropriate explanation of cytochrome c-CL binding, we have undertaken a spectroscopic and kinetic study of the wild type and the Asn52Ile mutant of iso-1-cytochrome c from yeast to investigate the interaction of cytochrome c with CL vesicles, considered here a model for the CL-containing mitochondrial membrane. Replacement of Asn52, an invariant residue located in a small helix segment of the protein, may provide data useful to gain novel information on which region of cytochrome c is involved in the binding reaction with CL vesicles. In agreement with our recent results revealing that two distinct transitions take place in the cytochrome c-CL binding reaction, data obtained here support a model in which two (instead of one, as considered so far) adjacent acyl chains of the liposome are inserted, one at each of the hydrophobic sites, into the same cytochrome c molecule to form the cytochrome c-CL complex.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding Sites
  • Cardiolipins / chemistry*
  • Cytochromes c / biosynthesis
  • Cytochromes c / chemistry*
  • Cytochromes c / isolation & purification
  • Kinetics
  • Mitochondrial Membranes / chemistry*
  • Models, Molecular

Substances

  • Cardiolipins
  • Cytochromes c