Lytic polysaccharide monooxygenases (LPMOs) are oxidative enzymes employed by fungi to depolymerize cellulose and thus of great academic and industrial (e.g. biorefinery) interest. The exact way or ways natural electron and H2O2 supply occurs to LPMOs during natural fungal LPMO action (and activation) remains unclear. Recent evidence suggests that LPMOs benefit from two oxidative enzymes (i.e. polyphenol oxidases (PPOs) and laccases) that are active on (poly)phenolic compounds. This gives rise to a new paradigm that places lignin as a protagonist in the activation of cellulose degradation, and not simply an obstacle to biomass decay. FuelingLPMO aims to investigate if and how a novel group of uncharacterized flavoenzymes, which I and other researchers have independenlty reported to be commonly co-secreted with AA9 LPMOs by ascomycetes during lignocellulose degradation, can regulate LPMO activity by modifying lignin-derived compounds, as well as deepen the current understanding on the mechanisms involved in LPMO activation by PPOs and laccases. We will use a combination of genome database mining, proteomics analysis and enzyme synergy characterization to investigate the co-occurence of genes encoding for AA9 LPMOs and these putative LPMO regulatory enzymes among Ascomycota, validate their co-secretion during lignocellulose degradation and test their hypothesized role in the regulation of cellulose degradation by AA9 LPMOs in vitro. The project will form a collaboration between the two research laboratories that made the ground-breaking discoveries of the PPO-mediated and laccase-mediated activation of LPMOs and exploit the multi-/interdisciplinary nature of their studies. Our findings will contribute to a more detailed understanding of the network of redox reactions involved in lignocellulose degradation by ascomycetes, building on the hypothesis that such understanding can be used to design powerful enzyme systems for efficient biomass conversion into bioproducts.
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