title: Membrane mediated regulation in free peptides of HIV-1 gp41: minimal modulation of the hemifusion phase.
abstract: Membrane-mediated structural modulation in two short fragments of the human HIV-1 envelope protein gp41 is demonstrated. Derived from the C-terminal membrane proximal external (MPE) and N-terminal fusion peptide proximal (FPP) regions, these peptides are widely separated in the primary sequence but form tertiary contacts during the intermediate (hemifusion) phase of HIV infection. The structural perturbations observed at the membrane interface offer evidence of rudimentary regulatory mechanisms operating in the free peptides which may be relevant in the biological system. No such regulatory phenomena were observed for the individual peptides in a membrane environment or between the peptides in aqueous solutions. Structure determination is made using a combination of circular and linear dichroism spectroscopy (supported by calorimetric measurements) and molecular dynamics simulations. Specifically, we show that these peptides interact locally without the conformational support of helical heptad repeat regions in native gp41 and that the modulation is not mutual with the FPP peptide operating as a primary regulator of the MPE-FPP interactions in the hemifusion phase.
authors.affiliation: National Physical Laboratory, Hampton Road, Teddington, TW11 0WL, UK.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Cerasoli
authors.forename: Jascindra
authors.initials: J
authors.lastname: Ravi
authors.forename: Craig
authors.initials: C
authors.lastname: Gregor
authors.forename: Rohanah
authors.initials: R
authors.lastname: Hussain
authors.forename: Giuliano
authors.initials: G
authors.lastname: Siligardi
authors.forename: Glenn
authors.initials: G
authors.lastname: Martyna
authors.forename: Jason
authors.initials: J
authors.lastname: Crain
authors.forename: Maxim G
authors.initials: MG
authors.lastname: Ryadnov
mesh_terms: D002942:Circular Dichroism; D015700:HIV Envelope Protein gp41 / Q000737:chemistry* / Q000378:metabolism; D015497:HIV-1 / Q000378:metabolism; D006801:Humans; D008567:Membranes, Artificial; D056004:Molecular Dynamics Simulation; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism; D017510:Protein Folding
chemical_list: D015700:HIV Envelope Protein gp41; D008567:Membranes, Artificial; D010455:Peptides; C514787:gp41 protein, Human immunodeficiency virus 1