title: Transmembrane helix tilting: insights from calculating the potential of mean force.
abstract: To explore the microscopic forces governing the helix tilting in membranes, we have calculated the potential of mean force (PMF) as a function of tilt angle (tau) of WALP19, a transmembrane model peptide, in a dimyristoylphosphatidylcholine membrane. The PMF shows a wide range of thermally accessible tilt angles (5 degrees to 22 degrees ) with a minimum at tau=12.5 degrees . The free energy decomposition reveals that the helix tilting up to tau=12.5 degrees is mostly driven by the entropy contribution arising from the helix precession around the membrane normal, whereas the PMF increase after tau=12.5 degrees results from helical deformation due to the sequence-specific helix-lipid interactions.
authors.affiliation: Department of Molecular Biosciences and Center for Bioinformatics, The University of Kansas, 2030 Becker Drive, Lawrence, KS 66047, USA.
authors.forename: Jinhyuk
authors.initials: J
authors.lastname: Lee
authors.forename: Wonpil
authors.initials: W
authors.lastname: Im
mesh_terms: D008051:Lipid Bilayers / Q000737:chemistry; D008565:Membrane Proteins / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular; D017433:Protein Structure, Secondary; D013816:Thermodynamics
chemical_list: D008051:Lipid Bilayers; D008565:Membrane Proteins