The long-term goal of this project is to understand at the molecular level the mechanisms that control synthesis and activity of the enzymes that convert acetyl CoA and oxaloacetate to glutamate in Bacillus subtilis. This pathway, which is critical for generation of energy, reducing power, and biosynthetic building blocks, is also the junction between carbon and nitrogen metabolism and plays a key regulatory role in bacterial differentiation. Previous work on this project has led to the discovery or identification of seven proteins (CcpC, CcpA, CodY, GltC, GltR, TnrA, and RocR) that participate in regulation of the genes that encode these enzymes. The specific aims of the present proposal are to uncover the molecular mechanisms by which several of these regulatory proteins control transcription of the citrate synthase, aconitase, isocitrate dehydrogenase, glutamate synthase, and glutamate dehydrogenase genes and to discover the effector molecules that control the activities of some of the regulatory proteins. The B. subtilis system is the primary paradigm for studies of Gram-positive bacteria and of prokaryotic differentiation. Fundamental studies of B. subtilis gene expression, regulation of metabolism and response to the environment are highly informative about the biology of related pathogenic bacteria and provide a means of studying issues of universal biological importance in an organism that is easily manipulated physiologically and genetically.