Structure-based discovery of a non-canonical prototype long-chain monoacylglycerol lipase through an endogenous catalysis intermediate complex

Abstract

ABSTRACTThe identification and characterization of enzyme function is lacking behind the rapidly increasing availability of large numbers of sequences and associated high-resolution structures. This often hampered by lack of knowledge on in vivo relevant substrates. Here, we present a case study where the high-resolution structure of an unusual orphan lipase in complex with an endogenous C18 monoacyl catalysis intermediate allowed its functional characterization as long-chain monacylglycerol lipase. Different from most other lipases, this enzyme uses a minimal helix–β-hairpin–helix lid domain that positions the substrate through a hydrophobic tunnel directly to the enzyme’s active site. Knowledge about the molecular details of the substrate binding site and hydrolysis allowed us to boost the enzymatic activity by adjusting protein/substrate interactions. This enzyme serves as a prototype for non-conventional esterases and lipases that share similar helix–β-hairpin–helix lid domains of variable size. Taken together, our data provide crucial insight to advance our knowledge of unusual esterases and lipases, facilitating future biotechnology applications.