The enzyme α-isopropylmalate synthase (α-IPMS) catalyzes the first step of L-leucine biosynthesis and is regulated via feedback inhibition by L-leucine. The gene of α-IPMS variant from strain ARTP-L04 was cloned and sequenced. Interestingly, amino acid mutations of Gly92Asp, Ile162Val, Arg494His and Gly526Asp occurred in the α-IPMS variant. The enzyme of α-IPMS variant was characterized, and exhibited higher resistance to feedback inhibition by L-leucine. In the presence of 20 mM L-leucine, the activity of the α-IPMS variant was still retained at over 50%. The α-IPMS variant almost removed feedback inhibition by L-leucine, while there was no significant difference in specific activities of the α-IPMS variant and wild-type α-IPMS. For the α-IPMS variant, the capacity to overproduce L-leucine was evaluated by recombinant Corynebacterium glutamicum strains. Interestingly, expression of the α-IPMS variant could significantly enhance L-leucine production, especially co-expressed with acetohydroxyacid synthase (accumulating 7.79 g/L L-leucine). Collectively, our findings provided valuable insights into further development in genetic engineering for L-leucine production.

α-异丙基苹果酸合酶 (α-IPMS) 催化 L-亮氨酸生物合成的第一步，并通过 L-亮氨酸的反馈抑制进行调节。对菌株 ARTP-L04 的 α-IPMS 变体基因进行了克隆和测序。有趣的是，Gly92Asp、Ile162Val、Arg494His 和 Gly526Asp 的氨基酸突变发生在 α-IPMS 变体中。对 α-IPMS 变体的酶进行了表征，并对 L-亮氨酸的反馈抑制表现出更高的抵抗力。在 20 mM L-亮氨酸存在下，α-IPMS 变体的活性仍保持在 50% 以上。α-IPMS 变体几乎消除了 L-亮氨酸的反馈抑制，而 α-IPMS 变体和野生型 α-IPMS 的比活性没有显着差异。对于 α-IPMS 变体，通过重组评估了过量生产 L-亮氨酸的能力谷氨酸棒杆菌菌株。有趣的是，α-IPMS 变体的表达可以显着增强 L-亮氨酸的产生，尤其是与乙酰羟酸合酶共表达（积累 7.79 g/L L-亮氨酸）。总的来说，我们的研究结果为 L-亮氨酸生产的基因工程的进一步发展提供了宝贵的见解。