Insights into buforin II membrane translocation from molecular dynamics simulations.

Buforin II is a histone-derived antimicrobial peptide that readily translocates across lipid membranes without causing significant membrane permeabilization. Previous studies showed that mutating the sole proline of buforin II dramatically decreases its translocation. As well, researchers have proposed that the peptide crosses membranes in a cooperative manner by forming transient toroidal pores. This paper reports molecular dynamics simulations designed to investigate the structure of buforin II upon membrane entry and evaluate whether the peptide is able to form toroidal pore structures. These simulations showed a relationship between protein-lipid interactions and increased structural deformations of the buforin N-terminal region promoted by proline. Moreover, simulations with multiple peptides show how buforin II can embed deeply into membranes and potentially form toroidal pores. Together, these simulations provide structural insight into the translocation process for buforin II in addition to providing more general insight into the role proline can play in antimicrobial peptides.