Insights from Micro-second Atomistic Simulations of Melittin in Thin Lipid Bilayers.

The membrane disruption and pore-forming mechanism of melittin has been widely explored by experiments and computational studies. However, the precise mechanism is still enigmatic, and further study is required to turn antimicrobial peptides into future promising drugs against microbes. In this study, unbiased microsecond (µs) time scale (total 17 µs) atomistic molecular dynamics simulation were performed on multiple melittin systems in 1,2-dimyristoyl-sn-glycero-3-phosphocholine membrane to capture the various events during the membrane disorder produced by melittin. We observed bent U-shaped conformations of melittin, penetrated deeply into the membrane in all simulations, and a special double U-shaped structure. However, no peptide transmembrane insertion, nor pore formation was seen, indicating that these processes occur on much longer timescales, and suggesting that many prior computational studies of melittin were not sufficiently unbiased.