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    基于底物通道的半理性设计实现PaBVMO催化效率-底物抑制-稳定性的三重协同

    Semi-Rational Design of Substrate Channels for PaBVMO to Achieve Triple Synergy of Catalytic Efficiency-Substrate Inhibition-Stability

    • 摘要: 来自Pseudomonas aeruginosa的Baeyer-Villiger 单加氧酶(PaBVMO)能选择性地在10-氧代硬脂酸上羰基的非常规一侧插入氧原子,生成癸二酸辛酯。为突破癸二酸生物合成中PaBVMO在高底物浓度下催化效率低与底物抑制显著的双重瓶颈,本文提出酶的底物通道半理性重塑策略。通过酶-底物的结合自由能与底物受力分析,解析出底物通道关键门控性环结构。结果表明,获得的最优突变体PaBVMOG398A的催化转化数达到3.45×104,比母本提升了5.3倍,比活力提升了0.7倍,同时失活半衰期从1.87 h延长至6.14 h,稳定性显著增强。通过高斯加速分子动力学(GaMD)模拟,解析了G398A突变诱导PaBVMOG398A的活性口袋发生重排,进而促发PaBVMOG398A对10-氧代硬脂酸催化的底物抑制程度降低、对辅因子FAD的亲和力增强、同时稳定性提高的协同机制。

       

      Abstract: Baeyer-Villiger monooxygenase from Pseudomonas aeruginosa (PaBVMO) selectively inserts an oxygen atom into the unconventional side of the carbonyl group of 10-carbonyl stearic acid to produce octyl sebacate, which can be used for synthesizing material monomers sebacic acid and 8-hydroxyoctanoic acid. To break through the dual bottleneck of low catalytic efficiency and significant substrate inhibition of PaBVMO under high substrate concentrations in sebacic acid biosynthesis, this study proposed a semi-rational remodeling strategy for the enzyme's substrate channel. Through the analysis of enzyme-substrate binding free energy and substrate force, the key gating loop structure of the substrate channel was resolved. Based on this strategy, the optimal mutant PaBVMOG398A was obtained. It exhibited a catalytic turnover number (TON) of 3.45×104, which was 5.3 times higher than that of the parent, and 0.7 times higher than that of the parental enzyme. Meanwhile, the inactivation half-life was prolonged from 1.87 h to 6.14 h, and the stability is significantly enhanced. Gaussian-accelerated molecular dynamics (GaMD) simulations further revealed the synergistic mechanism of G398A mutation inducing the rearrangement of the active pocket of PaBVMOG398A. This rearrangement effectively alleviated substrate inhibition by 10-carbonyl stearic acid, enhanced affinity for FAD and improved.

       

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