Activity of Spore-Specific Respiratory Nitrate Reductase 1 of Streptomyces coelicolor A3(2) Requires a Functional Cytochrome bcc-aa 3 Oxidase Supercomplex

Abstract

Streptomyces coelicolor forms spores that respire with either oxygen or nitrate, using only endogenous electron donors. This helps maintain a membrane potential and, thus, viability. Respiratory nitrate reductase (Nar) usually receives electrons directly from reduced quinone species; however, we show that nitrate respiration in spores requires a respiratory supercomplex comprising cytochrome bcc oxidoreductase and aa 3 oxidase. Our findings suggest that the Nar1 enzyme in the S. coelicolor spore functions together with the proton-translocating bcc-aa 3 supercomplex to help maintain the membrane potential more efficiently. Dissecting the mechanisms underlying this survival strategy is important for our general understanding of bacterial persistence during infection processes and of how bacteria might deal with nutrient limitation in the natural environment.