REGULATORS OF AEROBIC AND ANAEROBIC RESPIRATION IN BACILLUS-SUBTILIS

Two Bacillus subtilis genes, designated resD and resE, encode proteins that are similar to those of two-component signal transduction system s and play a regulatory role in respiration, The overlapping resD-resE genes are transcribed during vegetative growth from a very weak promo ter directly upstream of resD. They are also part of a larger operon t hat includes three upstream genes, resABC (formerly orfX14, -15, and - 16), the expression of which is strongly induced postexponentially, Re sD is required for the expression of the following genes: resA, ctaA ( required for heme A synthesis), and the petCBD operon (encoding subuni ts of the cytochrome bf complex), The resABC genes are essential genes which encode products with similarity to cytochrome c biogenesis prot eins. resD null mutations are more deleterious to the cell than those of resE, resD mutant phenotypes, directly related to respiratory funct ion, include streptomycin resistance, lack of production of aa(3) or c aa(3) terminal oxidases, acid accumulation when grown with glucose as a carbon source, and loss of ability to grow anaerobically on a medium containing nitrate. A resD mutation also affected sporulation, carbon source utilization, and Pho regulon regulation. The data presented he re support an activation role for ResD, and to a lesser extent ResE, i n global regulation of aerobic and anaerobic respiration in B. subtili s.