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 IsPETase(EHA) 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 IsPETase(EHA)-mediated hydrolytic efficiency by up to 1.3-fold. Notably, the stimulatory effects of PcAA14A on IsPETase(EHA)-catalyzed PET hydrolysis were found to be independent of monooxygenase activity. Dose-effects of IsPETase(EHA) and PcAA14A on PET hydrolysis were observed, with the optimal concentrations being determined to 25 mu g/mL and 0.25 mu g/mL, respectively. In the 5-day PET hydrolysis experiment, 1097 mu M hydrolysis products were produced by adding the optimized concentrations of IsPETase(EHA) and PcAA14A, which was 27.7% higher than those were produced by IsPETase(EHA) alone. Our study reports the first time that PcAA14A could stimulate the IsPETase(EHA)-mediated PET hydrolysis through a monooxygenase activity independent manner.

Automated summary

This study demonstrated the synergistic effects of combining PET-degrading enzyme IsPETase(EHA) and lytic polysaccharide monooxygenase PcAA14A in PET degradation. PcAA14A alone did not hydrolyze PET, but it enhanced the hydrolytic efficiency of IsPETase(EHA) by 1.3-fold. The stimulatory effects of PcAA14A on IsPETase(EHA) are independent of monooxygenase activity, and the optimal concentrations for PET hydrolysis were determined to be 25 μg/mL of IsPETase(EHA) and 0.25 μg/mL of PcAA14A. The presence of PcAA14A increased the hydrolysis products by 27.7% compared to IsPETase(EHA) alone.