A predicted structure of the cytochrome c oxidase from Burkholderia pseudomallei

Abstract

Cytochrome c oxidase, the terminal enzyme of the respiratory chains of mitochondria and aerobic bacteria, catalyzes electron transfer from cytochrome c to molecular oxygen. The enzyme belongs to the haem-copper-containing oxidases superfamily. A recombinant plasmid carrying a 2.0 kb insert from a Burkholderia pseudomallei genomic library was subjected to automated DNA sequencing utilizing a primer walking strategy. Analysis of the 2002 bp insert revealed a 1536 bp open reading frame predicted to encode a putative cytochrome c oxidase. Further analysis using sequence alignments and tertiary structure analysis tools demonstrated that the hypothetical B. pseudomallei cytochrome c oxidase is similar to cytochrome c oxidases from other organisms such as Thermus thermophilus (36% protein sequence identity), Paracoccus denitrificans and bovine heart mitochondrial, the latter two which crystal structures available. The deduced 512 residue protein sequence includes the six canonical histidine residues involved in binding the low spin heme B and the binuclear center CuB/hemeA. The predicted tertiary structure of the hypothetical protein is consistent with previous models of electron transfer for cytochrome c oxidase.