Capture of an early fusion-active conformation of HIV-1 gp41

Furuta, Rie; Wild, Carl; Weng, Yongkai; Weiss, Carol D.

doi:10.1038/871

Cited by 126 publications

(197 citation statements)

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“…Because previous studies indicate that the prehairpin can be triggered by CD4 alone (6,12,22), we examined the time course of conformational changes induced by cells expressing CD4.…”

Section: Resultsmentioning

confidence: 99%

“…Because previous studies indicate that the prehairpin can be triggered by CD4 alone (6,12,22), we examined the time course of conformational changes induced by cells expressing CD4. For these experiments, we used NIH3T3 cells that have been engineered to express equal levels of cell surface CD4 as NIH3T3 cells, which express both CD4 and CXCR4.…”

Section: Resultsmentioning

confidence: 99%

“…Binding of the NC-1 MAb reached a maximum value after 15 min and then declined to the background after about 30 min when fusion started to take off. The fact that the NC-1 MAb binds trimeric N35 CCG -N13 (see Figure 1) indicates the appearance by immunostaining (Figures 3 and 4) of an N-terminal trimeric gp41 prehairpin intermediate, which occurs significantly prior to 6-helix bundle formation.Because previous studies indicate that the prehairpin can be triggered by CD4 alone (6,12,22), we examined the time course of conformational changes induced by cells expressing CD4.For these experiments, we used NIH3T3 cells that have been engineered to express equal levels of cell surface CD4 as NIH3T3 cells, which express both CD4 and CXCR4. As shown in Figure 5, the kinetics of NC-1 MAb binding to HIV-1 LAI Env-expressing cells following incubation with NIH3T3CD4 exhibits a pattern similar to that following incubation with NIH3T3CD4CXCR4.…”

mentioning

confidence: 99%

“…The increased reactivity has been observed in the absence of gp120 dissociation (25), indicating that subunit dissociation is not absolutely required for these CD4-induced conformational changes to occur. The sensitivity of HIV-1 Env primed by sCD4 or cell-surface-bound CD4 (6,12,22,26) to N-or C-helical region peptides leads to the hypothesis that the immunoreactive gp41 antigen is reflecting exposure of the gp41 prehairpin fusion intermediate. While there seems to be general concurrence on the CD4-triggered conformational changes in gp41 that lead to the appearance of prehairpin conformations prior to the fusion event, there is disagreement regarding the formation of the 6-helix bundle relative to fusion.…”

mentioning

confidence: 99%

“…If CD4 is sufficient to trigger 6-helix bundle formation, the question arises as to why coreceptors are required for the fusion event. It has been suggested that the coreceptors function by facilitating other events in the fusion process (6). Golding and co-workers (29) proposed that the 6-helix bundles help bring the cellular and viral membranes in close proximity and that subsequent higher order clustering of the 6-helix bundles facilitates membrane fusion.…”

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Conformational Changes in HIV-1 gp41 in the Course of HIV-1 Envelope Glycoprotein-Mediated Fusion and Inactivation

et al. 2005

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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 °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.Membrane fusion mediated by human immunodeficiency virus (HIV)-1 1 envelope glycoproteins (gp120-gp41) is a critical step in the entry of the virus into susceptible cells (1). The current model of HIV viral entry involves the binding of the trimeric viral envelope glycoprotein gp120/gp41 to cell-surface receptor CD4 and chemokine coreceptor CXCR4 or CCR5 (2, 3), which triggers conformational changes in the envelope proteins (4). gp120 then disengages from gp41, allowing for the fusion peptide to be inserted into the target membrane and the prehairpin configuration of the ectodomain to form (5-7). The C-terminal heptad repeat region (C-helical region) and the leucine/isoleucine zipper region (N-helical region) 2 1 Abbreviations: HIV, human immunodeficiency virus; DMEM, Dulbecco's modified Eagle medium; CHO, Chinese hamster ovary; Cy5, N,; PBS, phosphate-buffered saline; D-PBS, Dulbecco's PBS; CMAC, Tricine,glycine. 2 For convenience, we use the notation N-and C-helical regions or peptides, although they only become α-helical when associated as homo-or heterotrimers. NIH Public Access NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript the thermostable 6-helix bundle (8-11), which drives the membrane merger and eventual fusion (12). In addition to structural information, a wealth of HIV Env-mediated fusion data, which includes inhibition by peptides that mimic the sequences of the N-and C-helical regions (13-21) and fusion kinetics (22), has lent credence to this model. In the absence of complete structural information, some of the details of the HIV-1 Env-mediated fusion reaction have been inferred from immunochemi...

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“…Because previous studies indicate that the prehairpin can be triggered by CD4 alone (6,12,22), we examined the time course of conformational changes induced by cells expressing CD4.…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Conformational Changes in HIV-1 gp41 in the Course of HIV-1 Envelope Glycoprotein-Mediated Fusion and Inactivation

et al. 2005

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HIV fusion and its inhibition in antiretroviral therapy

Greenberg¹,

Cammack

Salgo

et al. 2004

Reviews in Medical Virology

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The end of the twentieth century saw dramatic improvements in the prognosis of HIV infection brought about by the introduction of new agents (the protease inhibitors and the non-nucleoside reverse transcriptase inhibitors) and their use in highly active combinations. However, the durability of these combination treatments is limited by a number of factors including adverse effects and extensive intra-class cross-resistance so that new antiretrovirals acting on alternative targets and having improved systemic tolerability profiles are required. The HIV binding and entry process offers several potential targets for antiviral interaction. These include gp120 binding to CD4 and to chemokine co-receptor molecules as well as the fusion process itself, which involves interactions between two leucine zipper-like 4-3 repeat regions within gp41 known as heptad repeat (HR)1 and HR2. Peptides such as enfuvirtide (formerly DP178 or T-20), that mimic the HR2 region of gp41, inhibit HIV-1 by a mechanism that is thought to involve competitive binding to HR1. This review summarises the clinical development of enfuvirtide, providing an overview of the pharmacokinetic, efficacy and safety data in various patient populations, and also considers the evidence for the key role of genotypic changes in the HR1 region (amino acids 36-45) in determining viral susceptibility to inhibition by enfuvirtide.

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Structure and Function of Viral Glycoproteins in Membrane Fusion

Weissenhorn

Structure-Function Relationships of Human Pathogenic Viruses

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Capture of an early fusion-active conformation of HIV-1 gp41

Cited by 126 publications

References 0 publications

Conformational Changes in HIV-1 gp41 in the Course of HIV-1 Envelope Glycoprotein-Mediated Fusion and Inactivation

Conformational Changes in HIV-1 gp41 in the Course of HIV-1 Envelope Glycoprotein-Mediated Fusion and Inactivation

HIV fusion and its inhibition in antiretroviral therapy

Structure and Function of Viral Glycoproteins in Membrane Fusion

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