Enhanced Poly(ethylene terephthalate) Hydrolase Activity by Protein Engineering

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 hydrophobic sites, and has further illustrated the potential of biodegradable plastics.