Characterization of an AA10 lytic polysaccharide monooxygenase from Micromonospora aurantiaca and its synergistic mechanism with chitinase in boosting chitin conversion

Lytic polysaccharide monooxygenases (LPMOs) are auxiliary redox enzymes crucial for the bioconversion of crystalline polysaccharides. This study presents the structural and functional characterization of a novel AA10 family LPMO, designated Ma LPMO10C, derived from Micromonospora aurantiaca . Recombinant Ma LPMO10C exhibited C1-specific oxidative cleavage activity against α -chitin and β -chitin. Notably, Ma LPMO10C displayed strong synergistic effects with its cognate chitinase Ma Chi1 through a sequential reaction, achieving 3.4– and 1.5–fold enhancements in the conversion efficiencies of α -chitin and β -chitin, respectively, compared with Ma Chi1 alone. Structural and physicochemical analyses revealed that Ma LPMO10C pretreatment enhances chitinase accessibility to the substrate by increasing amorphous regions, reducing crystallinity, and lowering the polymerization degree of chitin. When Ma LPMO10C pretreatment (1.50 U/mL, 24 h) was combined with Ma Chi1 hydrolysis (1.50 U/mL, 36 h), remarkable conversion yields of 67.5 % for α -chitin and 100 % for β -chitin to (GlcNAc) 2 and GlcNAc were achieved. The high catalytic efficiency and robust synergistic performance of Ma LPMO10C make it a promising biocatalyst for industrial-scale chitin processing.