C-terminal ACT domain of the bifunctional chorismate mutase-prephenate dehydratase (CM-PDT) enzyme and the prephenate dehydratase (PDT) enzyme
The C-terminal ACT domain of the bifunctional chorismate mutase-prephenate dehydratase (CM-PDT) enzyme and the prephenate dehydratase (PDT) enzyme, found in plants, fungi, bacteria, and archaea. The P-protein of E. coli (CM-PDT, PheA) catalyzes the conversion of chorismate to prephenate and then the decarboxylation and dehydration to form phenylpyruvate. These are the first two steps in the biosynthesis of L-Phe and L-Tyr via the shikimate pathway in microorganisms and plants. The E. coli P-protein (CM-PDT) has three domains with an N-terminal domain with chorismate mutase activity, a middle domain with prephenate dehydratase activity, and an ACT regulatory C-terminal domain. The prephenate dehydratase enzyme has a PDT and ACT domain. The ACT domain is essential to bring about the negative allosteric regulation by L-Phe binding. L-Phe binds with positive cooperativity; with this binding, there is a shift in the protein to less active tetrameric and higher oligomeric forms from a more active dimeric form. Members of this CD belong to the superfamily of ACT regulatory domains.