title: Dynamical and Phase Behavior of a Phospholipid Membrane Altered by an Antimicrobial Peptide at Low Concentration.
abstract: The mechanism of action of antimicrobial peptides is traditionally attributed to the formation of pores in the lipid cell membranes of pathogens, which requires a substantial peptide to lipid ratio. However, using incoherent neutron scattering, we show that even at a concentration too low for pore formation, an archetypal antimicrobial peptide, melittin, disrupts the regular phase behavior of the microscopic dynamics in a phospholipid membrane, dimyristoylphosphatidylcholine (DMPC). At the same time, another antimicrobial peptide, alamethicin, does not exert a similar effect on the DMPC microscopic dynamics. The melittin-altered lateral motion of DMPC at physiological temperature no longer resembles the fluid-phase behavior characteristic of functional membranes of the living cells. The disruptive effect demonstrated by melittin even at low concentrations reveals a new mechanism of antimicrobial action relevant in more realistic scenarios, when peptide concentration is not as high as would be required for pore formation, which may facilitate treatment with antimicrobial peptides.
authors.affiliation: Biology and Soft Matter Division, Neutron Sciences Directorate, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.|Solid State Physics Division, Bhabha Atomic Research Centre , Mumbai 400085, India.
authors.forename: V K
authors.initials: VK
authors.lastname: Sharma
authors.affiliation: Chemical and Engineering Materials Division, Neutron Sciences Directorate, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors.forename: E
authors.initials: E
authors.lastname: Mamontov
authors.affiliation: National Institute of Standards and Technology Center for Neutron Research , Gaithersburg, Maryland 20899, United States.|Department of Materials Science and Engineering, University of Maryland , College Park, Maryland 20742, United States.
authors.forename: M
authors.initials: M
authors.lastname: Tyagi
authors.affiliation: Biology and Soft Matter Division, Neutron Sciences Directorate, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors.forename: S
authors.initials: S
authors.lastname: Qian
authors.affiliation: Biology and Soft Matter Division, Neutron Sciences Directorate, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors.forename: D K
authors.initials: DK
authors.lastname: Rai
authors.affiliation: Biology and Soft Matter Division, Neutron Sciences Directorate, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors.forename: V S
authors.initials: VS
authors.lastname: Urban