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

Abstract 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.