L-aspartate oxidase is the B protein, NadB, of the quinolinate synthetase complex. Quinolinate synthetase makes a precursor of the pyridine nucleotide portion of NAD. This model identifies proteins that cluster as L-aspartate oxidase (a flavoprotein difficult to separate from the set of closely related flavoprotein subunits of succinate dehydrogenase and fumarate reductase) by both UPGMA and neighbor-joining trees. The most distant protein accepted as an L-aspartate oxidase (NadB), that from Pyrococcus horikoshii, not only clusters with other NadB but is just one gene away from NadA. [Biosynthesis of cofactors, prosthetic groups, and carriers, Pyridine nucleotides]
Jiyao W et al.(2023). "The conserved domain database in 2023.",