Structural Basis of PET Depolymerase, Cut190, and Its Improved Function and Stability

Abstract

A cutinase-like enzyme from a thermophilic isolate, Saccharomonospora viridis AHK190, Cut190, has the ability to depolymerize polyethylene terephthalate (PET). The catalytic activity and thermal stability of Cut190 are increased by Ca²⁺ binding. The structural analysis of Cut190 mutants in complex with metal ions and substrates elucidated the reaction mechanism regulated by Ca²⁺. The metal ion-binding properties, analyzed using isothermal titration calorimetry were correlated with the effects on Cut190 activity and stability, which could be improved using protein engineering. The Cut190 mutant will be used for PET chemical recycling.