Enhanced Poly(ethylene terephthalate) Hydrolase Activity by Protein Engineering

摘要

Poly(ethylene terephthalate) hydrolase (PETase) from Ideonella sakaiensis exhibits a strong ability to degrade poly(ethylene terephthalate) (PET) at room temperature,and is thus regarded as a potential tool to solve the issue of polyester plastic pollution.Therefore,we explored the interaction between PETase and the substrate (a dimer of the PET monomer ethylene terephthalate,2PET),using a model of PETase and its substrate.In this study,we focused on six key residues around the substrate-binding groove in order to create novel high-efficiency PETase mutants through protein engineering.These PETase mutants were designed and tested.The enzymatic activities of the R61A,L88F,and I179F mutants,which were obtained with a rapid cell-free screening system,exhibited 1.4 fold,2.1 fold,and 2.5 fold increases,respectively,in comparison with wild-type PETase.The I179F mutant showed the highest activity,with the degradation rate of a PET film reaching 22.5 mg per μmol·L-1 PETase per day.Thus,this study has created enhanced artificial PETase enzymes through the rational protein engineering of key hvdrophobic sites,and has further illustrated the potential of biodegradable plastics.