Structure of a lytic polysaccharide monooxygenase from Aspergillus fumigatus and an engineered thermostable variant

Lytic polysaccharide monooxygenases (LPMOs) are industrial enzymes which are gaining use in second generation bioethanol production from lignocellulose by acting in synergy with glycoside hydrolases. Here we present the X-ray crystal structure of an AA9 fungal LPMO from Aspergillus fumigatus and a variant which has been shown to have better performance at elevated temperatures. Based on the structures, thermal denaturation data and theoretical calculations, we provide a suggestion for the structural basis of the improved stability. [Display omitted] •A fungal lytic polysaccharide monooxygenase (LPMO) was investigated (AfAA9_B).•The AfAA9_B structure was determined by crystallography in a copper –loaded state.•Guided by the TaAA9_A structure, variant L90V/D131S/M134L/A141W was designed.•This AfAA9_B variant has a Tm 7 °C higher than the native protein.•The local structure around mutations replicates well the design template.