Conformational changes in HIV-1 gp41 in the course of HIV-1 envelope glycoprotein-mediated fusion and inactivation.
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.
Dimitrov
Antony S
AS
Center for Cancer Research, Nanobiology Program, National Cancer Institute, National Institutes of Health, Frederick, Maryland 21702, USA.
Louis
John M
JM
Bewley
Carole A
CA
Clore
G Marius
GM
Blumenthal
Robert
R
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
D016915:AIDS Vaccines; D015700:HIV Envelope Protein gp41