通过S-柠檬烯合酶突变体的动力学分析揭示萜烯合酶进化的机制

使用孔雀绿比色法分析了S-柠檬烯合酶(S-limonene synthase,S-LS)野生型和突变体的动力学特性.研究表明,萜烯合酶经过引入少数残基突变合成新型萜烯化合物仍然可以保持酶的催化活性.该特性可以解释植物中是如何进化出新的萜烯合酶,从而解释了自然界中萜烯化合物的多样性.本研究提出了萜烯合酶的进化模型.同时针对生物合成中萜烯化合物产量不高的难题,为定向改造萜烯合酶提供了解决方法.

Kinetics of S-limonene synthase mutants reveals a novel evolutionary mechanism of terpene synthases

Terpene synthases have high specificity through divergent evolution,but how specificity evolved is not clear.In the present work,kinetics features of wild type and mutant S-limonene synthases were analyzed by colorimetric assay with malachite green as substrate.Compared with wild type enzyme,mutant increase in Km and decrease in kcat were found to be small.Kinetics data indicated that mutant terpene synthases which produce new terpene products still retain much of their overall activities.This character provides a novel mechanism for new monoterpene synthase evolution from existing enzymes and for diversification of terpenoids.The present work provides a model for terpene synthase evolution in nature,and offers solution to remodel terpene synthase to improve productivity of terpene biosynthesis.