Development of a highly active engineered PETase enzyme for polyester degradation

Abstract Polyethylene terephthalate (PET) accounts for ≈6% of global plastic production, contributing considerably to the global solid waste stream and environmental plastic pollution. Since the discovery of PET-depolymerizing enzymes, enzymatic PET recycling has been regarded as a promising method for plastic disposal, particularly in the context of a circular economy strategy. However, as the PET degrading enzymes developed so far suffer from relatively limited thermostability, low catalytic efficiency, as well as degradation intermediate-induced inhibition, their large scale industrial applications are still largely hampered. To overcome these limitations, we used in silico protein design methods to develop an engineered Leaf-branch Compost Cutinase (LCC), named DRK3, that features enhanced thermal stability and PETase activity relative to the current gold standard LCC enzyme (LCC-ICCG). DRK3 features a 4.1°C increase in melting temperature relative to the LCC-ICCG enzyme. Under optimal reaction conditions (68°C), the DRK3 enzyme hydrolyzes amorphous PET material into TPA with a 2-fold higher efficiency compared to LCC-ICCG. Owing to its enhanced properties, DRK3 may be a promising candidate for future applications in industrial PET recycling processes. Graphical abstract