title: Recognition and blocking of HIV-1 gp41 pre-transmembrane sequence by monoclonal 4E10 antibody in a Raft-like membrane environment.
abstract: The conserved (664)DKWASLWNWFNITNWLWYIK(683) (preTM) sequence preceding the transmembrane anchor of human immunodeficiency virus (HIV-1) gp41 glycoprotein subunit is accessible to the broadly neutralizing 4E10 antibody and, therefore, constitutes a potential target for vaccine design. Recently reported structural data are compatible with preTM insertion into the viral external membrane monolayer in the gp41 pre-fusion state (Zhu, P., Liu, J., Bess, J., Chertova, E., Lifson, J. D., Grisé, H., Ofek, G. A., Taylor, K. A., and Roux, K. H. (2006) Nature 441, 847-852). Here we demonstrate that the broadly neutralizing 4E10 antibody is able to specifically block the membrane-restructuring activity of a peptide mimic inserted into membranes. Recognition and restructuring blocking occurred in the presence of cholesterol, whereas transmembrane versions as those promoted in 1-palmitoyl-2-oleoylphosphatidylcholine:sphingomyelin mixtures could not be effectively arrested. Spectrofluorimetric assays using rhodamine-labeled peptides revealed that recognition correlated better with pore-formation blocking than with membrane-fusion inhibition. The capacity of the antibody to recognize preTM peptides in a raft-like environment was further corroborated employing planar-supported lipid layers and fluorescence microscopy. These data support that membrane-bound epitope recognition by 4E10 results in clustering reorganization of preTM at the membrane interface. We propose that this process might interfere with the formation of fusion-competent complexes at the low spike densities existing in the HIV-1 membrane. This work comprises the first experimental report on a lipid-modulated antibody capacity to bind a membrane-bound epitope sequence and arrest its restructuring activity.
authors.affiliation: Biophysics Unit (Consejo Superior de Investigaciones Científicas-UPV/EHU) and Biochemistry Department, University of the Basque Country, P. O. Box 644, 48080 Bilbao, Spain.
authors.forename: Maier
authors.initials: M
authors.lastname: Lorizate
authors.forename: Antonio
authors.initials: A
authors.lastname: Cruz
authors.forename: Nerea
authors.initials: N
authors.lastname: Huarte
authors.forename: Renate
authors.initials: R
authors.lastname: Kunert
authors.forename: Jesús
authors.initials: J
authors.lastname: Pérez-Gil
authors.forename: José L
authors.initials: JL
authors.lastname: Nieva
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry*; D016466:CHO Cells; D002784:Cholesterol / Q000737:chemistry; D006224:Cricetinae; D000939:Epitopes / Q000737:chemistry; D015700:HIV Envelope Protein gp41 / Q000737:chemistry*; D006801:Humans; D007700:Kinetics; D008055:Lipids / Q000737:chemistry; D021962:Membrane Microdomains / Q000737:chemistry*; D008954:Models, Biological; D010455:Peptides / Q000737:chemistry; D011485:Protein Binding; D013050:Spectrometry, Fluorescence
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; D015700:HIV Envelope Protein gp41; D008055:Lipids; D010455:Peptides; D002784:Cholesterol