 These domoic acid biosynthesis genes, or ‘Dab’ enzymes were heterologously expressed, characterized, and annotated as "dabA" (terpene cyclase), "dabB" (hypothetical protein), "dabC" (α-ketoglutarate–dependent dioxygenase), and "dabD" (CYP450).Domoic acid biosynthesis begins with the DabA-catalyzed geranylation of L-glutamic acid (L-Glu) with geranyl pyrophosphate (GPP) to form "N-geranyl"-L-glutamic acid (L-NGG).DabD then performs three successive oxidation reactions at the 7′-methyl of L-NGG to produce 7′-carboxy-L-NGG, which is then cyclized by DabC to generate the naturally occurring isodomoic acid A.Finally, an uncharacterized isomerase could convert isodomoic acid A to domoic acid.