title: Two states of cyclic antimicrobial peptide RTD-1 in lipid bilayers.
abstract: RTD-1 is a recently discovered cyclic peptide that, like other well-studied antimicrobial peptides, appears to bind to the lipid matrix of cell membrane in the initial stage of activity. We studied the states of RTD-1 bound to lipid bilayers by two methods: oriented circular dichroism and X-ray diffraction. RTD-1 shows two physically distinct bound states in lipid bilayers like magainins, protegrins, alamethicin, and melittin that were previously studied. However, the nature of transition between the two states is different for RTD-1 as compared with the aforementioned peptides. In one of the two states, RTD-1 is oriented with its backbone ring parallel to the plane of the bilayer. Only in this state RTD-1 induces membrane thinning. But the effect of membrane thinning is much weaker than all other peptides, suggesting that the mechanism of RTD-1 may be different from the other peptides.
authors.affiliation: Department of Physics & Astronomy, Rice University, Houston, TX 77251, USA.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Weiss
authors.forename: Lin
authors.initials: L
authors.lastname: Yang
authors.forename: Lai
authors.initials: L
authors.lastname: Ding
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Waring
authors.forename: Robert I
authors.initials: RI
authors.lastname: Lehrer
authors.forename: Huey W
authors.initials: HW
authors.lastname: Huang
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry*; D002942:Circular Dichroism; D008051:Lipid Bilayers; D010456:Peptides, Cyclic / Q000737:chemistry*; D014961:X-Ray Diffraction; D023084:alpha-Defensins / Q000737:chemistry*
chemical_list: D000900:Anti-Bacterial Agents; C429483:DEFA1A3 protein, human; D008051:Lipid Bilayers; D010456:Peptides, Cyclic; D023084:alpha-Defensins