Functional characterization of a novel copper-dependent lytic polysaccharide monooxygenase TgAA11 from Trichoderma guizhouense NJAU 4742 in the oxidative degradation of chitin.

Lytic polysaccharide monooxygenases (LPMOs) are attracting much attention for their potential application in biodegradation. However, there are limited studies on the characterization of the AA11 family. Here, a novel AA11 family protein, TgAA11, from Trichoderma guizhouense NJAU 4742 was characterized, and the isothermal titration calorimetry (ITC) analysis results showed that it exhibited tight binding capacity for copper ions with a Kd value of 4.83 ± 0.79 μM. The MALDI-TOF-MS analysis results indicated that TgAA11 could act on β-chitin to form C1 oxidation products, and some deacetylated chitooligosaccharides. In addition, the degradation of α-chitin and β-chitin by a chitinolytic enzyme Sg-chi was substantially increased in the presence of TgAA11 by 39.9 % and 288.2 %, respectively. Furthermore, the active site residues predicted showed that His61 and Tyr142 might be critical for the active site residues of the TgAA11 protein. This study will contribute to the understanding of the function of AA11 LPMOs in the degradation of chitin.