title: Conformational partitioning of the fusion peptide of HIV-1 gp41 and its structural analogs in bilayer membranes.
abstract: Experiments have shown that the ability of the HIV-1 virus to infect cells can be greatly diminished by deactivation of the N-terminal (fusion) peptide of its glycoprotein gp41. Deactivation can be achieved by the deletion of several amino acid residues, or replacement of a hydrophobic residue with a polar residue, to form mutant variants of the wild-type peptide. We report Monte Carlo simulation studies of a simplified peptide/membrane model, representing the interaction of an HIV-1 fusion peptide (FP) and four closely related mutagens with a lipid bilayer. In agreement with experimental results, we show that FP inserts deeply into the bilayer at approximately 40 degrees to the bilayer normal. We also show a previously unreported behavior of membrane peptides, namely their equilibrium partitioning between several distinct conformations within the bilayer. We quantify this partitioning behavior and characterize each conformation in terms of its geometry, energy, and entropy. The diminished ability of FP mutagens to hemolyse and aggregate red blood cells due to their partitioning into unfavorable conformations, is also discussed. Our analysis supports a negative curvature mechanism for red blood cell hemolysis by FP. We also suggest that the small repulsive forces between surface-adsorbed peptides in opposing membrane surfaces may block aggregation.
authors.affiliation: Department of Chemical Engineering and Materials Science, University of California-Davis, One Shields Avenue, Davis, CA 95616, USA.
authors.forename: Michael W
authors.initials: MW
authors.lastname: Maddox
authors.forename: Marjorie L
authors.initials: ML
authors.lastname: Longo
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry; D002462:Cell Membrane / Q000737:chemistry; D003198:Computer Simulation; D004735:Energy Transfer; D015700:HIV Envelope Protein gp41 / Q000737:chemistry*; D015497:HIV-1 / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D008051:Lipid Bilayers / Q000737:chemistry*; D046911:Macromolecular Substances; D008954:Models, Biological; D008956:Models, Chemical; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D011487:Protein Conformation; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D013499:Surface Properties; D014760:Viral Fusion Proteins / Q000737:chemistry
chemical_list: D000596:Amino Acids; D015700:HIV Envelope Protein gp41; D008051:Lipid Bilayers; D046911:Macromolecular Substances; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D014760:Viral Fusion Proteins