title: Molecular dynamics simulations of histidine-containing cod antimicrobial peptide paralogs in self-assembled bilayers.
abstract: Gaduscidin-1 and -2 (GAD-1 and GAD-2) are antimicrobial peptides (AMPs) that contain several histidine residues and are thus expected to exhibit pH-dependent activity. In order to help elucidate their mechanism of membrane disruption, we have performed molecular dynamics simulations with the peptides in both histidine-charged and histidine-neutral forms, along with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) lipid molecules. The simulations employed GROMACS software and an OPLS-AA force field. Initially, the peptide and lipids were placed randomly in the simulation box and then were allowed to self-assemble. The results demonstrated a marked preference for the regions of the peptides that contain sequential pairs of histidine residues to associate closely with bilayer pores. This preference is observed even when the histidines are in their uncharged form. It appears that the relative compactness and rigidity of histidine pairs require the more aqueous and disordered environment of the pores to satisfy hydrophilic interactions. The final peptide structures exhibited a wide variety of structures and topologies, with the most helical structures positioning most parallel to the bilayer surface and the less ordered structures interacting more closely with the pore. Thus, the results give atomistic insight into those models of AMP mechanism that promote the importance of structural heterogeneity and imperfect amphipathicity to AMP activity and selectivity.
authors: Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John's, NL A1B 3X7, Canada.
authors: Mohammad Hassan
authors: MH
authors: Khatami
authors: Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John's, NL A1B 3X7, Canada.
authors: Marek
authors: M
authors: Bromberek
authors: Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John's, NL A1B 3X7, Canada.
authors: Ivan
authors: I
authors: Saika-Voivod
authors: Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John's, NL A1B 3X7, Canada; Department of Biochemistry, Memorial University of Newfoundland, St. John's, NL A1B 3X9, Canada. Electronic address: vbooth@mun.ca.
authors: Valerie
authors: V
authors: Booth
keywords: Antimicrobial peptide; GROMACS; Histidine; Molecular dynamics; POPC; Simulation