An iron-sulfur protein that requires a [4Fe-4S] cluster for activity [1]. Quinolinate synthase catalyses the second step in the de novo biosynthesis of NAD+ from aspartate in some bacteria, with EC 1.4.3.16 (L-aspartate oxidase) catalysing the first step and EC 2.4.2.19 [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 [5].
