Differential effects of glutamate-286 mutations in the aa3-type cytochrome c oxidase from Rhodobacter sphaeroides and the cytochrome bo3 ubiquinol oxidase from Escherichia coli

► We compare E286 mutations in the oxidases from R. sphaeroides and E. coli. ► E286C in E. coli cyt bo3 blocks proton flux through the D-channel. ► E286C/A/Q causes extensive conformational changes in the R. sphaeroides oxidase. ► Differences are ascribed to residues surrounding E286 in the two oxidases.