Catalyzes the condensation of iminoaspartate with dihydroxyacetone phosphate to form quinolinate. dihydroxyacetone phosphate + iminosuccinate = H(+) + 2 H2O + phosphate + quinolinate Binds 1 [4Fe-4S] cluster per subunit. Activity is greater under oxic conditions and is regulated by the formation of a reversible disulfide-bond between Cys-291 and Cys-294. Cofactor biosynthesis; NAD(+) biosynthesis; quinolinate from iminoaspartate: step 1/1. Monomer (PubMed:18674537). Homodimer (PubMed:15967443). Belongs to the quinolinate synthase family. Type 1 subfamily.