Exploit and elucidate chaperone assisted PET hydrolase for upcycling plastics

Polyethylene terephthalate (PET) is the most abundant plastic waste in the environment. Currently, a new biocatalyst PETase, was discovered in 2016 from Ideonella sakaiensis bacteria, owned the high ability to digest PET through a mild and sustainable process. However, the high-level production of PETase in the model Escherichia coli remains a challenge and limits its application. Therefore, we employed the native molecular chaperones from Ideonella sakaiensis to improve the quality and quantity of an outstanding PETase variant, FAST-PETase (FA) at the first time. We selected GroELS from E. coli (EcG) and I. sakaiensis (IsG) using three genetic designs while the co-expressing FA with IsG chaperone increased soluble FA and elevated its activity by 25%. On the other hand, through the genome mining of I. sakaiensis, we identified a lipase secretion chaperone (IsLsC) at the upstream of native PETase. When co-expressing IsLsC and FA, the degradation efficiency toward PET film was up to 51.7 % within one day at 50 °C. More LsC-like chaperones could be explored from the sequence similarity network (SSN) with corresponding function to IsLsC. Finally, molecular docking and dynamic simulation exploited a hydrogen bond formation between FA and IsLsC to stabilizing the overall structure. The discovery of a novel chaperone offers a promising strategy for attractive PETase engaging in PET waste valorization.