Catalyzes the condensation of iminoaspartate with dihydroxyacetone phosphate to form quinolinate. Can complement nadA-deficient E.coli mutant. Essential for the de novo synthesis of NAD. Participates also in cysteine desulfurization mediated by NFS2. Can activate the cysteine desulfurase activity of NFS2 in vitro. dihydroxyacetone phosphate + iminosuccinate = H(+) + 2 H2O + phosphate + quinolinate Binds 1 [4Fe-4S] cluster per subunit. Cofactor biosynthesis; NAD(+) biosynthesis; quinolinate from iminoaspartate: step 1/1. Homodimer (PubMed:17452319). Interacts in vitro with NFS2, CpNIFS3 and AO (PubMed:18978034). Part of a Cys defulfurase complex (Probable). Expressed in roots, leaves, stems and flowers. Embryonic lethality when homozygous. The highly oxygen-sensitive (4Fe-4S) cluster at its NadA domain, can be reconstituted by its own SufE domain in the presence of NFS2, cysteine and ferrous iron. Belongs to the quinolinate synthase family. Type 1 subfamily.