Herbicide-Resistant Mutant Forms of Acetohydroxyacid Synthase

摘要

Acetohydroxyacid synthase (AHAS; EC 4.1.3.18) catalyses the first step in the biosynthesis of the branched-chain amino acids. The reaction involves the decarboxylation of pyruvate followed by condensation of the resulting hydroxyethyl group with either pyruvate or 2-ketobutyrate forming acetolactate or acetohydroxybutyrate, respectively. Essential cofactors for activity are thiamin diphosphate, Mg~(2+) and FAD. Several chemical classes of herbicide such as the sulfonylureas and imidazolinones act by inhibiting AHAS.