高级检索

    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(可用于合成材料单体癸二酸及8-羟基辛酸)。为突破癸二酸生物合成中PaBVMO在高底物浓度下的催化效率低下与底物抑制显著的双重瓶颈,本研究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。基于该策略,本研究获得的最优突变体PaBVMOG398A的催化转化数达3.45×104,比母本提升了6.3倍,比活力提升了1.7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。采用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 to synthesize material monomers sebacic acid and 8-hydroxyoctanoic acid). In order to break through the dual bottleneck of low catalytic efficiency and significant substrate inhibition of PaBVMO at 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 obtained in this study gave a catalytic turnover number (TON) of 3.45×104, which is 6.3 times higher than that of the parent, and 1.7 times higher than that of the parental enzyme. Meanwhile, the inactivation half-life is prolonged from 1.87 h to 6.14 h, and the stability is significantly enhanced. Gaussian-accelerated molecular dynamics (GaMD) simulations were used to elucidate the synergistic mechanism of G398A mutation inducing the rearrangement of the active pocket of PaBVMOG398A, which in turn induced the decrease in the substrate inhibition of PaBVMOG398A by 10-carbonyl stearic acid, the increase in affinity for FAD and the increase in stability.

       

    /

    返回文章
    返回