Structure-Guided Rational Design of a Mono- and Diacylglycerol Lipase from Aspergillus oryzae: A Single Residue Mutant Increases the Hydrolysis Ability

Engineering of enzymes on the basis of protein structures are rational and efficient approaches to acquire biocatalysts of desired performances. In this study, we focused on a special mono- and diacylglycerol lipase (MDGL) isolated from the lipolytic enzyme-enriched fungus Aspergillus oryzae and discovered improved variants based on its crystal structure. We first solved the crystal structure of Aspergillus oryzae lipase (AOL) at 1.7 Å resolution. Structure analysis and sequence alignment of AOL and other MDGLs revealed that the residue V269 is of vital importance for catalysis. Replacement of the V269 in AOL with the corresponding residues in other MDGLs has led to noticeable changes in hydrolysis without sacrificing the thermostability and substrate specificity. Among the investigated variants, V269D exhibited about a six-fold higher hydrolysis activity compared to the wild type. Molecular dynamics simulations and protein-ligand interaction frequency analyses revealed that the Asp substitution enhanced the substrate affinity of AOL. Our work sheds light on understanding the catalytic process of AOL and helps tailoring MDGLs with desired catalytic performance to fulfill the demand for biotechnological applications.