Type III Pyridoxal 5-phosphate (PLP)-Dependent Enzyme Bifunctional Aspartate Kinase/Diaminopimelate Decarboxylase
Bifunctional aspartate kinase/diaminopimelate decarboxylase (AspK/DapDC, EC 188.8.131.52/EC 184.108.40.206) typically exists in bacteria. These proteins contain an N-terminal AspK region and a C-terminal DapDC region, which contains a PLP-binding TIM-barrel domain followed by beta-sandwich domain, characteristic of fold type III PLP-dependent enzymes. Members of this subfamily have not been fully characterized. Based on their sequence, these proteins may catalyze both reactions catalyzed by AspK and DapDC. AspK catalyzes the phosphorylation of L-aspartate to produce 4-phospho-L-aspartate while DapDC participates in the last step of lysine biosynthesis, the conversion of meso-2,6-diaminoheptanedioate to L-lysine.