FMN-dependent alpha-hydroxy acid dehydrogenase; part of the gene cluster that mediates the biosynthesis of quinolactacin A2 (QUL A2), a fungal alkaloid that features a quinolone-gamma-lactam hybrid, which is a potential pharmacophore for the treatment of cancer and Alzheimer's disease (PubMed:32663343). The quinolone-gamma-lactam hybrid scaffold is synthesized from the combination of L-isoleucine (L-Ile) and the nonproteinogenic amino acid L-kynurenine, followed by quinolone cyclization, oxidative decarboxylation, and lactam formation (PubMed:32663343). Additionally, the N-methyl group is derived from methionine, which might be catalyzed by an S-adenosylmethionine (SAM)-dependent methyltransferase (PubMed:32663343). Bioconversion of L-tryptophan to L-kynurenine could be catalyzed by the indoleamine-2,3-dioxygenase (IDO) qulI to produce an unstable product, N-formyl-L-kynurenine, followed by kynurenine formamidase catalyzed hydrolysis (PubMed:32663343). QulM then acts as a methyltransferase that methylates L-kynurenine at the N-4 position (PubMed:32663343). The FMN-dependent alpha-hydroxy acid dehydrogenase qulF than functions as an oxidative decarboxylase which converts N-methylkynurenine into 2-aminobenzoylacetamide via 2 tandem reactions, including dehydrogenation and decarboxylation (PubMed:32663343). An amidase located outside of the qul gene cluster further produces the unstable beta-keto acid precursor N-methyl-2-aminobenzoylacetate, which could be spontaneously dehydrated to form N-methyl-4-hydroxy-2-quinolone (PubMed:32663343). The NRPS qulB is able to incorporate N-methyl-2-aminobenzoylacetate and efficiently compete with the spontaneous reaction (PubMed:32663343). By further extending the beta-keto acid with L-Ile, qulA performs a Dieckmann condensation to form the gamma-lactam ring and release a 4-ketopyrrolidinone intermediate from the assembly line (PubMed:32663343). This intermediate could plausibly further undergo a spontaneous cyclization to yield the final quinolone-gamma-lactam hybrid structure (PubMed:32663343). Impairs the production of quinolactacin A2 and leads to the accumulatin of N-methylkynurenine. Belongs to the FMN-dependent alpha-hydroxy acid dehydrogenase family.