title: Neutron reflectometry study of the conformation of HIV Nef bound to lipid membranes.
abstract: Nef is an HIV-1 accessory protein that directly contributes to AIDS progression. Nef is myristoylated on the N-terminus, associates with membranes, and may undergo a transition from a solution conformation to a membrane-associated conformation. It has been hypothesized that conformational rearrangement enables membrane-associated Nef to interact with cellular proteins. Despite its medical relevance, to our knowledge there is no direct information about the conformation of membrane-bound Nef. In this work, we used neutron reflection to reveal what we believe are the first details of the conformation of membrane-bound Nef. The conformation of Nef was probed upon binding to Langmuir monolayers through the interaction of an N-terminal His tag with a synthetic metal-chelating lipid, which models one of the possible limiting cases for myr-Nef. The data indicate that residues are inserted into the lipid headgroups during interaction, and that the core domain lies directly against the lipid headgroups, with a thickness of ∼40 A. Binding of Nef through the N-terminal His tag apparently facilitates insertion of residues, as no insertion occurred upon binding of Nef through weak electrostatic interactions in the absence of the specific interaction through the His tag.
authors.affiliation: Sandia National Laboratories, Albuquerque, New Mexico, USA. mskent@sandia.gov
authors.forename: Michael S
authors.initials: MS
authors.lastname: Kent
authors.forename: Jaclyn K
authors.initials: JK
authors.lastname: Murton
authors.forename: Darryl Y
authors.initials: DY
authors.lastname: Sasaki
authors.forename: Sushil
authors.initials: S
authors.lastname: Satija
authors.forename: Bulent
authors.initials: B
authors.lastname: Akgun
authors.forename: Hirsh
authors.initials: H
authors.lastname: Nanda
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Curtis
authors.forename: Jaroslaw
authors.initials: J
authors.lastname: Majewski
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Morgan
authors.forename: John R
authors.initials: JR
authors.lastname: Engen
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry / Q000378:metabolism; D019342:Acetic Acid / Q000737:chemistry / Q000378:metabolism; D000327:Adsorption; D000595:Amino Acid Sequence; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism*; D003300:Copper / Q000737:chemistry; D003903:Deuterium / Q000737:chemistry; D015497:HIV-1; D050356:Lipid Metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D033363:Neutron Diffraction / Q000379:methods*; D011485:Protein Binding; D011487:Protein Conformation; D021381:Protein Transport; D014961:X-Ray Diffraction; D054311:nef Gene Products, Human Immunodeficiency Virus / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D054311:nef Gene Products, Human Immunodeficiency Virus; C514837:nef protein, Human immunodeficiency virus 1; D015060:1,2-Dipalmitoylphosphatidylcholine; D003300:Copper; D003903:Deuterium; D019342:Acetic Acid