Molecular coevolution of the vertebrate cytochrome c(1) and Rieske iron sulphur protein in the cytochrome bc(1) complex.

Cytochrome c(1) (cyt-c(1)) and the Rieske Iron Sulphur Protein (ISP) are subunits of the cytochrome bc(1) complex located in the mitochondria functioning both as a proton pump and an electron transporter. Vertebrate model organism phylogenies were used in conjunction with existing 3D protein structures to evaluate the biochemical evolution of cyt-c(1) and ISP in terms of selection on amino acid properties. We found selection acting on the exterior surfaces of both proteins and specifically the core region of cyt-c(1). There is evidence supporting coevolution of these proteins relative to alpha helical tendencies, compressibility and equilibrium constant.