Comparative studies of two AA10 family lytic polysaccharide monooxygenases from .

, known to be one of the most important biocontrol microorganisms, contains three AA10 family lytic polysaccharide monooxygenases (LPMOs) in its genome. In previous reports, two of them, LPMO10A and LPMO10B, have been preliminarily characterized. However, some important biochemical features and substrate preference, as well as their potential applications in chitin degradation, still deserve further investigation. Results from present study showed that both LPMO10A and LPMO10B exhibit similar catalytic domains as well as highly conserved substrate-binding planes. However, unlike LPMO10A, which has comparable binding ability to both crystalline and amorphous form of chitins, LPMO10B exhibited much stronger binding ability to colloidal chitin, which mainly attribute to its carbohydrate-binding module-5 (CBM5). Interestingly, the relative high binding ability of LPMO10B to colloidal chitin does not lead to high catalytic activity of the enzyme. In contrast, the enzyme exhibited higher activity on -chitin. Further experiments showed that the binding of LPMO10B to colloidal chitin was mainly non-productive, indicating a complicated role for CBM5 in LPMO activity. Furthermore, synergistic experiments demonstrated that both LPMOs boosted the activity of the chitinase, and the higher efficiency of LPMO10A can be overridden by LPMO10B.