The yeast gene YJR025cencodes a 3‐hydroxyanthranilic acid dioxygenase and is involved in nicotinic acid biosynthesis

We have deleted the yeast gene YJR025cand shown that this leads to an auxotrophy for nicotinic acid. The deduced protein sequence of the gene product is homologous to the human 3‐hydroxyanthranilic acid dioxygenase (EC 1.13.11.6) which is part of the kynurenine pathway for the degradation of tryptophan and the biosynthesis of nicotinic acid. In cell‐free extracts the 3‐hydroxyanthranilic acid dioxygenase activity is proportional to the copy number of the YJR025cgene. As YJR025cencodes the yeast 3‐hydroxyanthranilic acid dioxygenase, we have named this gene BNA1for iosynthesis of icotinic cid.