Binding mode prediction of aplysiatoxin, a potent agonist of protein kinase C, through molecular simulation and structure-activity study on simplified analogs of the receptor-recognition domain.

Aplysiatoxin (ATX) is a naturally occurring tumor promoter isolated from a sea hare and cyanobacteria. ATX binds to, and activates, protein kinase C (PKC) isozymes and shows anti-proliferative activity against human cancer cell lines. Recently, ATX has attracted attention as a lead compound for the development of novel anticancer drugs. In order to predict the binding mode between ATX and protein kinase Cδ (PKCδ) C1B domain, we carried out molecular docking simulation, atomistic molecular dynamics simulation in phospholipid membrane environment, and structure-activity study on a simple acyclic analog of ATX. These studies provided the binding model where the carbonyl group at position 27, the hydroxyl group at position 30, and the phenolic hydroxyl group at position 20 of ATX were involved in intermolecular hydrogen bonding with the PKCδ C1B domain, which would be useful for the rational design of ATX derivatives as anticancer lead compounds.