Pseudomonas cytochrome c551 at 2.0 A resolution: enlargement of the cytochrome c family.

Abstract

The structure of respiratory cytochrome c551 of P. aeruginosa, with 82 amino acids, was solved by X-ray analysis and refined to a crystallographic R factor of 16.2%. It has the same basic folding pattern and hydrophobic heme environment as cytochromes c, c2 and c550, except for a large deletion at the bottom of the heme crevice. This same cytochrome fold appears to be present in photosynthetic cytochromes c of green and purple sulfur bacteria, and algal cytochromes f, suggesting a common evolutionary origin for electron transport chains in photosynthesis and respiration.