Click here to close Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly. We suggest using a current version of Chrome, FireFox, or Safari.
XB-ART-45875
Biophys J August 8, 2012; 103 (3): 472-482.

Reorientation and dimerization of the membrane-bound antimicrobial peptide PGLa from microsecond all-atom MD simulations.

Ulmschneider JP , Smith JC , Ulmschneider MB , Ulrich AS , Strandberg E .


Abstract
The membrane-active antimicrobial peptide PGLa from Xenopus laevis is known from solid-state (2)H-, (15)N-, and (19)F-NMR spectroscopy to occupy two distinct α-helical surface adsorbed states in membranes: a surface-bound S-state with a tilt angle of ~95° at low peptide/lipid molar ratio (P/L = 1:200), and an obliquely tilted T-state with a tilt angle of 127° at higher peptide concentration (P/L = 1:50). Using a rapid molecular-dynamics insertion protocol in combination with microsecond-scale simulation, we have characterized the structure of both states in detail. As expected, the amphiphilic peptide resides horizontally on the membrane surface in a monomeric form at a low P/L, whereas the T-state is seen in the simulations to be a symmetric antiparallel dimer, with close contacts between small glycine and alanine residues at the interface. The computed tilt angles and azimuthal rotations, as well as the quadrupolar splittings predicted from the simulations agree with the experimental NMR data. The simulations reveal many structural details previously inaccessible, such as the immersion depth of the peptide in the membrane and the packing of the dimerization interface. The study highlights the ability and limitations of current state-of-the-art multimicrosecond all-atom simulations of membrane-active peptides to complement experimental data from solid-state NMR.

PubMed ID: 22947863
PMC ID: PMC3414899
Article link: Biophys J


Species referenced: Xenopus laevis
Genes referenced: pgla

References [+] :
Afonin, Evaluating the amino acid CF3-bicyclopentylglycine as a new label for solid-state 19 F-NMR structure analysis of membrane-bound peptides. 2007, Pubmed