InterPro domain: IPR036094

Quinolinate synthetase catalyses the second step of the de novo biosynthetic pathway of pyridine nucleotide formation. In particular, quinolinate synthetase is involved in the condensation of dihydroxyacetone phosphate and iminoaspartate to form quinolinic acid [ 1 ]. This synthesis requires two enzymes, an FAD-containing "B protein" and an "A protein". B protein converts L-aspartate to iminoaspartate. The A protein, NadA, converts iminoaspartate to quinolate. NadA harbours a [4Fe-4S] cluster [ 2 ].

The structure of NadA is composed of three similar domains related by pseudo threefold symmetry. Each domain has three layers (alpha/beta/alpha) with parallel beta sheet.

1. Cloning, overexpression, and purification of Escherichia coli quinolinate synthetase. Protein Expr. Purif. 18, 64-70
2. Characterization of quinolinate synthases from Escherichia coli, Mycobacterium tuberculosis, and Pyrococcus horikoshii indicates that [4Fe-4S] clusters are common cofactors throughout this class of enzymes. Biochemistry 47, 10999-1012