Structural similarity of cytochrome c2 from Rhodopseudomonas viridis to mitochondrial cytochromes c revealed by its crystal structure at 2.7 Å resolution

Abstract

The crystal structure of cytochrome c 2 from Rhodopseudomonas viridis has been refined using molecular dynamics and restrained least-squares methods to a crystallographic R-factor of 0.216 at 2.7 Å resolution. A structural comparison between Rps. viridis cytochrome c 2 and the other bacterial cytochromes C 2 or mitochondrial cytochromes c indicates that the overall protein foldings are very similar to each other with the exception of the surface loop and terminal region of the polypeptide chain. However, the position and hydrogen-bond pattern of the evolutionarily conserved water molecule buried within the heme binding pocket in Rps. viridis cytochrome c 2 are common to those in the mitochondrial cytochromes c. This fact indicates that Rps. viridis cytochrome c 2 is structurally more similar to mitochondrial cytochromes c than to the other bacterial cytochromes c 2.