Control of Escherichia coli isocitrate dehydrogenase: an example of protein phosphorylation in a prokaryote

In micro-organisms growing on acetate, isocitrate can be metabolized either by the tricarboxylic acid cycle or by the glyoxylate bypass. In Escherichia coli this branch-point is controlled by reversible phosphorylation and inactivation of isocitrate dehydrogenase. Both phosphorylation and dephosphorylation are catalysed by a single bifunctional kinase/phosphatase. The properties of this enzyme suggest that phosphorylation of isocitrate dehydrogenase is controlled by the concentrations of several central metabolites, including isocitrate, the adenine nucleotides and phoenolpyruvate