Type III Pyridoxal 5-phosphate (PLP)-Dependent Enzyme Carboxynorspermidine Decarboxylase
Carboxynorspermidine decarboxylase (CANSDC) catalyzes the decarboxylation of carboxynorspermidine, the last step in the biosynthesis of norspermidine. It is homologous to eukaryotic ornithine decarboxylase (ODC) and diaminopimelate decarboxylase (DapDC), which are fold type III PLP-dependent enzymes that contain an N-terminal PLP-binding TIM-barrel domain and a C-terminal beta-sandwich domain, similar to bacterial alanine racemases. Based on this similarity, CANSDC may require homodimer formation and the presence of the PLP cofactor for its catalytic activity.