Characterization of AoAA11M: a new copper-dependent lytic polysaccharide monooxygenase for oxidative chitin...

Lytic polysaccharide monooxygenases (LPMOs), which are also known as the Auxiliary Activities (AA) family, have drawn a lot of interest because of their potential to help break down biomass. However, the AA11 family remains relatively understudied. In this study, we characterized a novel AA11 family protein, derived from Aspergillus oryzae RIB40, which we named AoAA11 M. Using isothermal titration calorimetry (ITC), electron paramagnetic resonance (EPR), and melting temperature (T_m) analysis, we confirmed that AoAA11 M could bind copper. MALDI-TOF-MS analysis showed that AoAA11 M could act on α-chitin at the C1 position, and also release some deacetylated chitooligosaccharides. When used together with chitinase, AoAA11 M boosted the degradation of α-chitin by 53.3%. Mutagenesis and activity assays pointed to His1, His69, and Tyr131 as key residues for catalytic activity. Our findings expand what we know about the AA11 family and highlight AoAA11 M as a promising biocatalyst for chitin valorization.