Solid-state NMR analysis of the PGLa peptide orientation in DMPC bilayers: structural fidelity of 2H-labels versus high sensitivity of 19F-NMR.
The structure and alignment of the amphipathic alpha-helical antimicrobial peptide PGLa in a lipid membrane is determined with high accuracy by solid-state 2H-NMR. Orientational constraints are derived from a series of eight alanine-3,3,3-d3-labeled peptides, in which either a native alanine is nonperturbingly labeled (4x), or a glycine (2x) or isoleucine (2x) is selectively replaced. The concentration dependent realignment of the alpha-helix from the surface-bound "S-state" to a tilted "T-state" by 30 degrees is precisely calculated using the quadrupole splittings of the four nonperturbing labels as constraints. The remaining, potentially perturbing alanine-3,3,3-d3 labels show only minor deviations from the unperturbed peptide structure and help to single out the unique solution. Comparison with previous 19F-NMR constraints from 4-CF3-phenylglycine labels shows that the structure and orientation of the PGLa peptide is not much disturbed even by these bulky nonnatural side chains, which contain CF3 groups that offer a 20-fold better NMR sensitivity than CD3 groups.
Strandberg
Erik
E
Institute for Biological Interfaces, Forschungszentrum Karlsruhe, 76344 Eggenstein-Leopoldshafen, Germany.
Wadhwani
Parvesh
P
Tremouilhac
Pierre
P
Dürr
Ulrich H N
UH
Ulrich
Anne S
AS
D023181:Antimicrobial Cationic Peptides / Q000737:chemistry*; D003903:Deuterium / Q000737:chemistry*; D004134:Dimyristoylphosphatidylcholine / Q000032:analysis / Q000737:chemistry*; D005461:Fluorine / Q000737:chemistry*; D008051:Lipid Bilayers / Q000032:analysis / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008560:Membrane Fluidity; D008565:Membrane Proteins / Q000737:chemistry; D011487:Protein Conformation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D023181:Antimicrobial Cationic Peptides; D008051:Lipid Bilayers; D008565:Membrane Proteins; C045866:peptide-Gly-Leu-amide; D005461:Fluorine; D003903:Deuterium; D004134:Dimyristoylphosphatidylcholine