An iron-sulfur protein that requires a [4Fe-4S] cluster for activity . Quinolinate synthase catalyses the second step in the de novo biosynthesis of NAD+ from aspartate in some bacteria, with EC 126.96.36.199
(L-aspartate oxidase) catalysing the first step and EC 188.8.131.52
[nicotinate-nucleotide diphosphorylase (carboxylating)] the third step. In Escherichia coli, two of the residues that are involved in the [4Fe-4S] cluster binding appear to undergo reversible disulfide-bond formation that regulates the activity of the enzyme .