Catalytically inactive lytic polysaccharide monooxygenase PcAA14A enhances the enzyme-mediated hydrolysis of polyethylene terephthalate.

The massive accumulation of polyethylene terephthalate (PET) in the global ecosystem is a growing environmental crisis. Development of environmental friendly strategies to achieve enzyme-catalyzed PET degradation has attracted tremendous attention. In this study, we demonstrated the synergistic effects of combining a specific PET-degrading enzyme IsPETaseEHA variant from PET-assimilating bacterium Ideonella sakaiensis and a lytic polysaccharide monooxygenase from a white-rot fungus Pycnoporus coccineus (PcAA14A) in PET degradation. We found that the presence of PcAA14A alone did not result in PET hydrolysis, but its presence could stimulate IsPETaseEHA-mediated hydrolytic efficiency by up to 1.3-fold. Notably, the stimulatory effects of PcAA14A on IsPETaseEHA-catalyzed PET hydrolysis were found to be independent of monooxygenase activity. Dose-effects of IsPETaseEHA and PcAA14A on PET hydrolysis were observed, with the optimal concentrations being determined to 25 μg/mL and 0.25 μg/mL, respectively. In the 5-day PET hydrolysis experiment, 1097 μM hydrolysis products were produced by adding the optimized concentrations of IsPETaseEHA and PcAA14A, which was 27.7% higher than those were produced by IsPETaseEHA alone. Our study reports the first time that PcAA14A could stimulate the IsPETaseEHA-mediated PET hydrolysis through a monooxygenase activity independent manner.