Type III Pyridoxal 5-phosphate (PLP)-Dependent Enzyme Y4yA
This subfamily is composed of the hypothetical Rhizobium sp. protein Y4yA and similar uncharacterized bacterial proteins. These proteins are homologous to eukaryotic ornithine decarboxylase (ODC) and diaminopimelate decarboxylase (DapDC). ODC and DapDC 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. ODC participates in the formation of putrescine by catalyzing the decarboxylation of ornithine, the first step in polyamine biosynthesis. DapDC participates in the last step of lysine biosynthesis, the conversion of meso-2,6-diaminoheptanedioate to L-lysine. Proteins in this subfamily may function as PLP-dependent decarboxylases.