title: Conformational changes in HIV-1 gp41 in the course of HIV-1 envelope glycoprotein-mediated fusion and inactivation.
abstract: HIV-1 envelope glycoprotein-mediated fusion is driven by the concerted coalescence of the HIV-1 gp41 N- and C-helical regions, which results in the formation of 6-helix bundles. These two regions are considered prime targets for peptides and antibodies that inhibit HIV-1 entry. However, the parameters that govern this inhibition have yet to be elucidated. We address this issue by monitoring the temporal sequence of conformational states of HIV-1 gp41 during the course of HIV-1-mediated cell-cell fusion by quantitative video microscopy using reagents that bind to N- and C-helical regions, respectively. Env-expressing cells were primed by incubation with target cells at different times at 37 degrees C followed by washing. The reactivity of triggered gp41 to the NC-1 monoclonal antibody, which we demonstrate here to bind to N-helical gp41 trimers, increased rapidly to a maximal level in the primed state but decreased once stable fusion junctions had formed. In contrast, reactivity with 5-helix, which binds to the C-helical region of gp41, increased continuously as a function of time following the priming. The peptide N36(Mut(e,g)) reduced NC-1 monoclonal antibody binding and enhanced 5-helix binding, consistent with the notion that this molecule promotes dissociation of gp41 trimers. This inactivation pathway may be important for the design of entry inhibitors and vaccine candidates.
authors.affiliation: Center for Cancer Research, Nanobiology Program, National Cancer Institute, National Institutes of Health, Frederick, Maryland 21702, USA.
authors.forename: Antony S
authors.initials: AS
authors.lastname: Dimitrov
authors.forename: John M
authors.initials: JM
authors.lastname: Louis
authors.forename: Carole A
authors.initials: CA
authors.lastname: Bewley
authors.forename: G Marius
authors.initials: GM
authors.lastname: Clore
authors.forename: Robert
authors.initials: R
authors.lastname: Blumenthal
mesh_terms: D016915:AIDS Vaccines; D015700:HIV Envelope Protein gp41 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015497:HIV-1 / Q000737:chemistry / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D008561:Membrane Fusion; D008958:Models, Molecular; D011487:Protein Conformation
chemical_list: D016915:AIDS Vaccines; D015700:HIV Envelope Protein gp41