Interplay of acidic residues in the proton channel of E. coli cytochrome bd-I oxidase to promote oxygen reduction and NO release.

The reduction of oxygen to water is crucial to life under aerobic conditions. Cytochrome bd oxidases perform this reaction with a very high oxygen affinity. Members of this protein family are solely found in prokaryotes and some archaea playing an important role in bacterial virulence and antibiotic resistance.