Two Bacillus subtilis genes, designated resD and resE, encode proteins that are similar to those of twocomponent signal transduction systems and play a regulatory role in respiration. The overlapping resD-resE genes are transcribed during vegetative growth from a very weak promoter directly upstream of resD. They are also part of a larger operon that includes three upstream genes, resABC (formerly orfX14, -15, and -16), the expression of which is strongly induced postexponentially. ResD is required for the expression of the following genes: resA, ctaA (required for heme A synthesis), and the petCBD operon (encoding subunits of the cytochrome bf complex). The resABC genes are essential genes which encode products with similarity to cytochrome c biogenesis proteins. resD null mutations are more deleterious to the cell than those of resE. resD mutant phenotypes, directly related to respiratory function, include streptomycin resistance, lack of production of aa 3 or caa 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 here support an activation role for ResD, and to a lesser extent ResE, in global regulation of aerobic and anaerobic respiration in B. subtilis.

BaciUlus subtilis has an alkaline phosphatase (APase) gene

The Pho regulon of Bacillus subtilis is controlled by three two-component signal-transduction systems: PhoP/PhoR, ResD/ResE, and the phosphorelay leading to the phosphorylation of SpoOA. Two of these systems act as positive regulators, while the third is involved in negative regulation of the Pho regulon. Under phosphate-starvation-induction conditions, the response regulator (RR) PhoP, and the histidine protein kinase (HK) PhoR, are involved in the induction of Pho-regulon genes including the phoPR operon and genes encoding the major vegetative alkaline phosphatases, phoA and phoB. ResD (the RR) and ResE (the HK) are positive regulators of both aerobic and anaerobic respiration in B. subtilis. Current data suggest that they are also positive regulators of the Pho regulon, as is the transition-state regulatory protein AbrB. Data presented reveal that ResDE and AbrB are involved in activation of the Pho regulon through separate regulatory pathways. SpoOA approximately P (RR) exerts a negative effect on the Pho regulon through its repression of AbrB, and possibly through repression of ResDE. Both pathways converge to regulate transcription of the phoPR operon.

No abstract