title: Fusion-competent state induced by a C-terminal HIV-1 fusion peptide in cholesterol-rich membranes.
abstract: The replicative cycle of the human immunodeficiency virus type-1 begins after fusion of the viral and target-cell membranes. The envelope glycoprotein gp41 transmembrane subunit contains conserved hydrophobic domains that engage and perturb the merging lipid bilayers. In this work, we have characterized the fusion-committed state generated in vesicles by CpreTM, a synthetic peptide derived from the sequence connecting the membrane-proximal external region (MPER) and the transmembrane domain (TMD) of gp41. Pre-loading cholesterol-rich vesicles with CpreTM rendered them competent for subsequent lipid-mixing with fluorescently-labeled target vesicles. Highlighting the physiological relevance of the lasting fusion-competent state, the broadly neutralizing antibody 4E10 bound to the CpreTM-primed vesicles and inhibited lipid-mixing. Heterotypic fusion assays disclosed dependence on the lipid composition of the vesicles that acted either as virus or cell membrane surrogates. Lipid-mixing exhibited above all a critical dependence on the cholesterol content in those experiments. We infer that the fusion-competent state described herein resembles bona-fide perturbations generated by the pre-hairpin MPER-TMD connection within the viral membrane.
authors.affiliation: Biophysics Unit (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080 Bilbao, Spain. Electronic address: beatriz.apellaniz@ehu.es.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Apellániz
authors.affiliation: Biophysics Unit (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080 Bilbao, Spain. Electronic address: joseluis.nieva@ehu.es.
authors.forename: José L
authors.initials: JL
authors.lastname: Nieva
mesh_terms: D002462:Cell Membrane / Q000737:chemistry* / Q000378:metabolism; D002784:Cholesterol / Q000737:chemistry* / Q000378:metabolism; D015700:HIV Envelope Protein gp41 / Q000737:chemistry* / Q000378:metabolism; D015497:HIV-1 / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D008561:Membrane Fusion / Q000502:physiology*; D008563:Membrane Lipids / Q000737:chemistry* / Q000378:metabolism; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism; D013109:Sphingomyelins
chemical_list: D015700:HIV Envelope Protein gp41; D008563:Membrane Lipids; D010446:Peptide Fragments; D013109:Sphingomyelins; D002784:Cholesterol
keywords: 4E10 antibody; Cholesterol; HIV MPER; HIV fusion; HIV gp41; Membrane fusion assay