While it is established that the topology of lipid membranes plays an important role in biochemical processes, few direct observations exist with respect to how the membranes are actively restructured and its consequences on subsequent reactions. In this work, we investigated how the two major components of bee venom, melittin and secretory phospholipase A2 (PLA2), achieve activation by such membrane remodeling. Melittin is a 26-mer lytic peptide, and PLA2 is a lipid-cleaving enzyme, and their membrane-disrupting functions have been reported to improve when both are present. Despite the extensive use of bee venom in traditional medicine and interest as a potential therapeutic agent for cancer and other ailments, the mechanism by which this synergistic effect occurs had not been established. We used membrane reconstitution and single-molecule fluorescence microscopy to observe their molecular interactions in real time. We found that melittin causes major structural modifications in supported lipid bilayers, forming large-scale membrane deformities that display 25-fold higher PLA2 activity. Single-molecule tracking revealed that PLA2 displays altered interactions with phospholipids in these deformities, resulting in increased interaction with the membrane and likely enzymatic processivity. These results suggest that melittin primes the membrane for PLA2 by inducing changes in the membrane structure. More broadly, they demonstrate how the membrane structure may have a significant impact on cellular membrane-bound reactions.

Membrane phospholipid hydrolysis by phospholipase A2 is accelerated by melittin-induced bilayer deformations

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.