ACT domains located C-terminal to the catalytic domain of the lysine-sensitive aspartokinase isoenzyme AKIII
This CD includes the first of two ACT domains located C-terminal to the catalytic domain of the lysine-sensitive aspartokinase isoenzyme AKIII, a monofunctional class enzyme found in bacteria (Escherichia coli (EC) LysC) and plants, (Zea mays Ask1, Ask2, and Arabidopsis thaliana AK1). Aspartokinase is the first enzyme in the aspartate metabolic pathway and catalyzes the conversion of aspartate and ATP to aspartylphosphate and ADP. Like the A. thaliana AK1 (AK1-AT), the E. coli AKIII (LysC) has two bound feedback allosteric inhibitor lysine molecules at the dimer interface located between the ACT1 domain of two subunits. The lysine-sensitive plant isoenzyme is synergistically inhibited by S-adenosylmethionine. A homolog of this group appears to be the Saccharomyces cerevisiae AK (Hom3) which clusters with this group as well. Members of this CD belong to the superfamily of ACT regulatory domains.