Creation of biocatalyst capable of biosynthesizing lactate-based polymers with highly regulated chirality

目前，已开发出高性能乳酸(LA)聚合物的微生物生产系统。该体系的一个突破是发现了“LA聚合酶(LPE)”。LPE是通过对微生物聚合物PHA合成酶的工程研究而产生的。通过从葡萄糖中导入LPE基因，在大肠杆菌中以一锅法合成了包括R-LA在内的高度对映异构体聚合物。基于辅酶A-转移酶和乳清蛋白的进化工程，尝试建立了S-LA单体聚合物的合成体系。通过代谢工程和酶工程的结合，使聚合物中LA的含量从6%提高到47%。此外，以LA为基础的聚合物表现出与对应的均聚物--聚乳酸和聚羟基丁酸酯--不同的性质。

Currently microbial production system for lactate(LA) polymers with high performances has been developed. A break-through of this system was a discovery of "LA-Polymerizing Enzyme(LPE)". LPE was created through the study on the engineering of microbial polymer PHA synthase. LA-based polymer was synthesized by highly enatiomeric monomers including R-LA in an one-pot manner in Escherichia coli by introduction of the LPE gene from glucose. I tried to establish the system for synthesis of the polymer incorporating S-LA monomer based on the evolutionary engineering of CoA-transferase and LPE. As a resiult, LA fraction in the polymer has been enriched up to 47% from 6% by combination of metabolic and enzyme engineering. Furthermore, LA-based polymers exhibited distinguishable properties from the counterpart homopolymers, PLA and PHB.