Lipoprotein lipase requires a flexible lid and stable C terminus maintained by ApoC-II peptide binding

Summary: Lipoprotein lipase (LPL) is the rate-limiting enzyme in lipoprotein metabolism, and its dysfunction contributes to cardiovascular and neurodegenerative disease. However, the conformational dynamics governing LPL activity and cofactor interactions remain poorly defined. Here, we perform comprehensive microscale molecular dynamics simulations of full-length LPL, incorporating a predicted lid domain and examining LPL alone and in complex with an apolipoprotein C-II mimetic peptide (ApoC-II-P). We show that the flexible lid adopts multiple orientations that regulate lipid pore accessibility, catalytic activity, and lipid binding. We also identify ∼180° flipping of the C-terminal domain (CTD). ApoC-II-P stabilizes LPL conformations by bridging the N-terminal domain (NTD) and CTD and maintaining lid flexibility. Biochemical and cellular assays corroborate these findings, demonstrating that ApoC-II-P markedly enhances LPL-mediated triglyceride hydrolysis and phagocytosis. Our findings reveal interdomain interactions governing LPL activity and support ApoC-II-P as a promising strategy to enhance LPL function and improve disease outcomes.