Interaction between AA9 lytic polysaccharide monooxygenase and PQQ-dependent pyranose dehydrogenase in cellulose degradation

Wood-decaying fungi degrade cellulose, the primary polysaccharide in wood, as a nutrient source by utilising various hydrolytic and oxidative enzymes. Among these, lytic polysaccharide monooxygenase (LPMO9) has gained attention as a key enzyme that enhances the degradation efficiency of other cellulases. The activity of LPMO9 requires both electrons and hydrogen peroxide. It has been reported that electron supply can be provided by redox enzymes such as PQQ-dependent pyranose dehydrogenase (PDH). Hydrogen peroxide is thought to be either generated by LPMO9 itself or utilised from that produced by PDH. In other words, PDH is a crucial enzyme that supply both electrons and hydrogen peroxide to drive LPMO9 catalytic activity. These enzymes often contain cellulose-binding domains such as CBM1 or CBM104. CBM1 and CBM104 could control the role of the catalytic domain by localising it to different regions of the cellulose substrate. However, the effects of CBMs on LPMO9 and PDH have not yet been elucidated. This study aimed to clarify how the presence or absence of CBMs, as well as their different types, influence the ability of PDH to drive LPMO9 activity. As a result, it was shown that ability of LPMO9 from Gloeophyllum trabeum has more potential than other LOMO9 (LPMO9 from Neurospora crassa). Additionally, data showed there had different amount of degradation products by each PDH.