Protein phosphorylation in bacteria has only recently been demonstrated. The first report was in E. coli, where an NADP- specific isocitrate dehydrogenase was identified as a substrate for the protein kinase. More recently, the phosphorylation of isocitrate lyase and enolase in E. coli has been reported. This project supports research to: 1) further characterize the phosphorylated forms of isocitrate lyase and enolase; 2) further purify and characterize protein kinases and phosphatases catlyzing the reversible phosphorylation of these two enzymes; 3) elucidate the regulation of cellular metabolism as it is affected by the post-translational modification of these two enzymes; 4) determine the factors which regulate the synthesis and expression of these activities; 5) investigate the unique regulation of isocitrate dehydrogenase activity in Acinetobacter calcoaceticus; and 6) investigate the role of prokaryotic protein kinases and other endogenous proteins in the regulation of eukaryotic metabolism. The reversible phosphorylation of regulatory enzymes and proteins is known to be an important mechanism for the metabolic control of a wide variety of cellular functions in many higher organisms, and in some viruses. Only recently has protein phosphorylation been demonstrated to occur in bacteria. It is now generally accepted that protein phosphorylation represents an important regulatory mechanism for a variety of physiological processes in many species of microorganisms. This research will examine the phosphorylation of bacterial enzymes, providing a better understanding of how bacterial metabolism is controlled. It will also provide insight into how this phosphorylation system interacts with that of higher organisms, and whether this might have any relationship to the process of infection.
