School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, 210009, People's Republic of China.
RWTH Aachen University, Templergraben 55, Aachen, 52062, Germany.
Nat Commun. 2023 Jul 13;14(1):4169. doi: 10.1038/s41467-023-39929-w.
Although considerable research achievements have been made to address the plastic crisis using enzymes, their applications are limited due to incomplete degradation and low efficiency. Herein, we report the identification and subsequent engineering of BHETases, which have the potential to improve the efficiency of PET recycling and upcycling. Two BHETases (ChryBHETase and BsEst) are identified from the environment via enzyme mining. Subsequently, mechanism-guided barrier engineering is employed to yield two robust and thermostable ΔBHETases with up to 3.5-fold enhanced k/K than wild-type, followed by atomic resolution understanding. Coupling ΔBHETase into a two-enzyme system overcomes the challenge of heterogeneous product formation and results in up to 7.0-fold improved TPA production than seven state-of-the-art PET hydrolases, under the conditions used here. Finally, we employ a ΔBHETase-joined tandem chemical-enzymatic approach to valorize 21 commercial post-consumed plastics into virgin PET and an example chemical (p-phthaloyl chloride) for achieving the closed-loop PET recycling and open-loop PET upcycling.
尽管使用酶来解决塑料危机已经取得了相当大的研究成果，但由于不完全降解和效率低下，它们的应用受到限制。在此，我们报告了 BHETases 的鉴定和后续工程，这有可能提高 PET 回收和升级利用的效率。通过酶挖掘从环境中鉴定出两种 BHETases（ChryBHETase 和 BsEst）。随后，采用机制导向的障碍工程，得到了两种具有更高热稳定性和更强活性的ΔBHETases，其 k/K 比野生型提高了 3.5 倍以上，并通过原子分辨率进行了理解。将 ΔBHETase 耦合到双酶系统中，克服了异质产物形成的挑战，在我们所采用的条件下，TPA 的产量比目前最先进的七种 PET 水解酶提高了 7.0 倍。最后，我们采用一种 ΔBHETase 连接的串联化学-酶方法，将 21 种商业消费后的塑料转化为原始 PET 和一种化学物质（对苯二甲酰氯），实现了闭环 PET 回收和开环 PET 升级利用。
