Recent Advance in Acetohydroxy Acid Synthase for the Production of Branched Chain Amino Acids

Acetohydroxy acid synthase (AHAS), a thiamine diphosphate (ThDP)-dependent enzyme, is the key enzyme that catalyzes the first step in the production of branched chain amino acids (BCAA), namely L-valine, L-leucine and L-isoleucine. AHAS is susceptible to feedback inhibition by the end product, BCAA, which inhibits the activity of the enzyme and affects carbon flux to BCAA. Therefore, AHAS is an important target for high-yield production of BCAA, and the modification of AHAS is of great significance. In this review, the structure, catalytic mechanism, and role of AHAS in the BCAA synthesis pathway are introduced. The current research status of the catalytic process of the enzyme and the current molecular modification strategies for AHAS are summarized. Finally, future research directions and modification strategies for the enzyme are proposed.