Abstract

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 (Tm) 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.