抄録
Lytic Polysaccharide Monooxigenases (LPMOs) classified into Auxiliary Activity (AA) family 9 of Carbohydrate Active enZymes (CAZy) database degrade insoluble cellulose and release oxidized cello-oligosaccharides as reaction products. PcLPMO9D is a LPMO secreted by the basidiomycete Phanerochaete chrysosporium. As other LPMOs from wood-rotting fungi, the enzyme has catalytic activity that degrades insoluble cellulose and release C1-oxidized cello-oligosaccharides. LPMOs are generally known to show synergy effect with other hydrolytic cellulases and "boost" the cellulose degradation. However, the mechanism of this synergism between LPMO and cellulases has been unclear. In this study, High speed Atomic Force Microscopy (HsAFM) observation was conducted to visualize the effect of PcLPMO9D on the motion of a hydrolytic cellulase PcCe17D on the crystalline cellulose. When PcLPMO9D was added to the reaction solution, the number of PcCe17D observed on the crystalline cellulose significantly increased, indicating PcLPMO9D creates the chain end of cellulose molecules where PcCe17D can bind and start the reaction. Moreover, PcCe17D found on extended area of cellulose crystal after addition of PcLPMO9D, suggesting that PcLPMO9D may act on the crystalline surface which is not accessible for PcCe17D without LPMO activity.
