title: Order parameters of a transmembrane helix in a fluid bilayer: case study of a WALP peptide.
abstract: A new solid-state NMR-based strategy is established for the precise and efficient analysis of orientation and dynamics of transmembrane peptides in fluid bilayers. For this purpose, several dynamically averaged anisotropic constraints, including (13)C and (15)N chemical shift anisotropies and (13)C-(15)N dipolar couplings, were determined from two different triple-isotope-labeled WALP23 peptides ((2)H, (13)C, and (15)N) and combined with previously published quadrupolar splittings of the same peptide. Chemical shift anisotropy tensor orientations were determined with quantum chemistry. The complete set of experimental constraints was analyzed using a generalized, four-parameter dynamic model of the peptide motion, including tilt and rotation angle and two associated order parameters. A tilt angle of 21 degrees was determined for WALP23 in dimyristoylphosphatidylcholine, which is much larger than the tilt angle of 5.5 degrees previously determined from (2)H NMR experiments. This approach provided a realistic value for the tilt angle of WALP23 peptide in the presence of hydrophobic mismatch, and can be applied to any transmembrane helical peptide. The influence of the experimental data set on the solution space is discussed, as are potential sources of error.
authors.affiliation: Utrecht University, Biochemistry of Membranes, Bijvoet Center for Biomolecular Research, Utrecht, The Netherlands.
authors.forename: Andrea
authors.initials: A
authors.lastname: Holt
authors.forename: Léa
authors.initials: L
authors.lastname: Rougier
authors.forename: Valérie
authors.initials: V
authors.lastname: Réat
authors.forename: Franck
authors.initials: F
authors.lastname: Jolibois
authors.forename: Olivier
authors.initials: O
authors.lastname: Saurel
authors.forename: Jerzy
authors.initials: J
authors.lastname: Czaplicki
authors.forename: J Antoinette
authors.initials: JA
authors.lastname: Killian
authors.forename: Alain
authors.initials: A
authors.lastname: Milon
mesh_terms: D016880:Anisotropy; D002462:Cell Membrane / Q000737:chemistry* / Q000378:metabolism*; D008051:Lipid Bilayers / Q000737:chemistry* / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism*; D017433:Protein Structure, Secondary; D011789:Quantum Theory
chemical_list: D008051:Lipid Bilayers; D010455:Peptides