HIV-1 gp41 Transmembrane Domain Interacts with the Fusion Peptide: Implication in Lipid Mixing and Inhibition of Virus–Cell Fusion

Reuven, Eliran Moshe; Dadon, Yakir; Viard, Mathias; Manukovsky, Nurit; Blumenthal, Robert; Shai, Yechiel

doi:10.1021/bi201721r

Cited by 55 publications

(80 citation statements)

References 90 publications

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“…Importantly, experiments performed with the intact virus demonstrated that a mutant in which the GxxxG motif within the TMD in the HXB2 envelope was altered, was defective in fusion (58). Furthermore, the FP and the TMD of HIV-1 heteroassemble in the membrane and synergize in inducing membrane fusion (55). A similar observation was previously demonstrated in the influenza virus, in which TMD-FP interactions were shown to play a key role in the fusion cascade (59).…”

Section: Discussionsupporting

confidence: 67%

“…gp41 TMD (FIMIVGGLVGLRIVFAVLSIV) is also highly conserved within different strains of HIV (53) and was suggested to play several roles during HIV-1 cell fusion, including anchoring the envelope glycoprotein to both viral and cellular membranes (54), assisting in the oligomerization of gp41 (55), inducing phospholipid vesicle fusion (55,56), promoting cell-cell fusion (57,58), and immunosuppressing T-cell activation (30). Importantly, experiments performed with the intact virus demonstrated that a mutant in which the GxxxG motif within the TMD in the HXB2 envelope was altered, was defective in fusion (58).…”

Section: Discussionmentioning

confidence: 99%

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A GxxxG-like Motif within HIV-1 Fusion Peptide Is Critical to Its Immunosuppressant Activity, Structure, and Interaction with the Transmembrane Domain of the T-cell Receptor

Faingold

Cohen

Shai

2012

Journal of Biological Chemistry

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Background: HIV utilizes its fusion peptide (FP) to both fuse and immunosuppress T-cells. Results: A conserved GxxxG-like motif within FP is critical for its function and structure. Conclusion: The GxxxG-like motif exerts its role via interaction with the transmembrane domain of TCR␣. Significance: We shed light on the molecular mechanism of FP immunosuppressant activity and on the molecular recognition within the membrane milieu.

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Section: Discussionsupporting

confidence: 67%

Section: Discussionmentioning

confidence: 99%

A GxxxG-like Motif within HIV-1 Fusion Peptide Is Critical to Its Immunosuppressant Activity, Structure, and Interaction with the Transmembrane Domain of the T-cell Receptor

Faingold

Cohen

Shai

2012

Journal of Biological Chemistry

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“…We speculate that formation of this trimeric state may be initiated by interactions between the polar segments of the NHR (S546-N554) and CHR (E647-K655) regions, which lack high membrane affinity but make tight and specific interhelical contacts in the 6HB. Specific interactions between the FP and TM (35), which are only accessible after formation of the fusogenic prebundle, may further stabilize formation of the postfusion state. Competition between intermolecular and membrane association may also be impacted by a shift in lipid composition after outer leaflet lipids of the viral and host cells can mix with one another by translational diffusion through the hemifusion stalk, which would be a slow and strongly temperature-dependent process.…”

Section: Discussionmentioning

confidence: 99%

Dissociation of the trimeric gp41 ectodomain at the lipid–water interface suggests an active role in HIV-1 Env-mediated membrane fusion

Roche

Louis

Grishaev

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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The envelope glycoprotein gp41 mediates the process of membrane fusion that enables entry of the HIV-1 virus into the host cell. The actual fusion process involves a switch from a homotrimeric prehairpin intermediate conformation, consisting of parallel coiled-coil helices, to a postfusion state where the ectodomains are arranged as a trimer of helical hairpins, adopting a six-helix bundle (6HB) state. Here, we show by solution NMR spectroscopy that a water-soluble 6HB gp41 ectodomain binds to zwitterionic detergents that contain phosphocholine or phosphatidylcholine head groups and phospholipid vesicles that mimic T-cell membrane composition. Binding results in the dissociation of the 6HB and the formation of a monomeric state, where its two α-helices, N-terminal heptad repeat (NHR) and C-terminal heptad repeat (CHR), become embedded in the lipid-water interface of the virus and host cell. The atomic structure of the gp41 ectodomain monomer, based on NOE distance restraints and residual dipolar couplings, shows that the NHR and CHR helices remain mostly intact, but they completely lose interhelical contacts. The high affinity of the ectodomain helices for phospholipid surfaces suggests that unzippering of the prehairpin intermediate leads to a state where the NHR and CHR helices become embedded in the host cell and viral membranes, respectively, thereby providing a physical force for bringing these membranes into close juxtaposition before actual fusion.T he first step of HIV infection involves fusion of the viral and target cell membranes, a process mediated by the viral envelope glycoprotein Env, consisting of subunits gp120 and gp41 (1). The envelope proteins form a noncovalent complex on the viral surface with the trimerized gp41 transmembrane subunit sequestered by three gp120 surface subunits (2-5). Binding of gp120 to the cell surface receptors CD4 and chemokine receptors CXCR4 or CCR5 triggers a cascade of conformational changes that disrupt the interactions between gp41 and gp120 and result in an extended gp41 conformation (1, 6). In this extended prefusion state, the highly hydrophobic N-terminal fusion peptide (FP) of gp41 anchors in the host cell membrane, while being spatially remote from its transmembrane domain (TM), which traverses the viral membrane (7,8). After the host cell and viral membranes have fused, the gp41 ectodomain, which links the FP and TM domains, has transitioned into a C3-symmetric six-helix bundle (6HB), with the FP in physical proximity to the TM domain (9). The refolding of gp41 trimers into the highly stable 6HB arrangement is believed to overcome the large free-energy barrier of membrane fusion. Several atomic resolution structures of the 6HB postfusion state have been solved by X-ray crystallography, confirming that the C-terminal heptad repeat (CHR) helices pack in an antiparallel manner into the conserved hydrophobic grooves formed at the surface of the central trimer of N-terminal heptad repeat (NHR) helices (10-12).Contrary to the postfusion state, structural features...

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“…For example, self-assembly of paramyxovirus (43,44), influenza virus (45,46), and HIV (47) F-protein transmembrane domains was demonstrated experimentally and is considered a determinant for proper protein folding and fusion activity (44,47). Studies with class I vFMGs have shown that insertion of synthetic, soluble fusion peptides into the membrane can deform the lipid bilayer (48) and induce membrane fusion (49).…”

Section: Discussionmentioning

confidence: 99%

Efficient replication of a paramyxovirus independent of full zippering of the fusion protein six-helix bundle domain

Brindley¹,

Plattet²,

Plemper³

2014

Proc. Natl. Acad. Sci. U.S.A.

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Enveloped viruses such as HIV and members of the paramyxovirus family use metastable, proteinaceous fusion machineries to merge the viral envelope with cellular membranes for infection. A hallmark of the fusogenic glycoproteins of these pathogens is refolding into a thermodynamically highly stable fusion core structure composed of six antiparallel α-helices, and this structure is considered instrumental for pore opening and/or enlargement. Using a paramyxovirus fusion (F) protein, we tested this paradigm by engineering covalently restricted F proteins that are predicted to be unable to close the six-helix bundle core structure fully. Several candidate bonds formed efficiently, resulting in F trimers and higher-order complexes containing covalently linked dimers. The engineered F complexes were incorporated into recombinant virions efficiently and were capable of refolding into a postfusion conformation without temporary or permanent disruption of the disulfide bonds. They efficiently formed fusion pores based on virus replication and quantitative cell-to-cell and virus-to-cell fusion assays. Complementation of these F mutants with a monomeric, fusion-inactive F variant enriched the F oligomers for heterotrimers containing a single disulfide bond, without affecting fusion complementation profiles compared with standard F protein. Our demonstration that complete closure of the fusion core does not drive paramyxovirus entry may aid the design of strategies for inhibiting virus entry. membrane fusion | measles virus M embrane fusion is an essential process in eukaryotic cell biology. Examples range from fusion of lipid vesicles to sustain intracellular transport along secretory and endocytotic pathways to cell fusion in fertilization and development and to the fusion of viral with cellular membranes resulting in viral infection. Because there are several high-energy barriers (1), lipid membranes do not merge spontaneously under physiological conditions and therefore require the aid of auxiliary proteins to induce membrane stress and lower the activation energy for lipid merger. For vesicular transport, for instance, soluble N-ethylmaleimide-sensitive factor-activating protein receptor (SNARE) proteins resident in both the target and donor membrane mediate the process (2). Two fundamental differences distinguish cellular fusion machineries from viral fusogenic membrane glycoproteins (vFMGs), which mediate the entry of enveloped viruses by the fusion of the envelope with cellular membranes: (i) vFMGs do not require adapter proteins but insert a fusion peptide domain into the target membrane; and (ii) vFMGs fold into metastable prefusion conformations, obviating the dependence on external energy sources. Three distinct types of viral fusion (F) proteins have been classified: class I vFMGs are found, among others, on influenza virus, retroviruses, and paramyxoviruses; class II proteins are present on alpha-and flaviviruses; and class III proteins mediate herpes-and rhabdovirus entry (reviewed in ref.3).Once the fusion p...

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HIV-1 gp41 Transmembrane Domain Interacts with the Fusion Peptide: Implication in Lipid Mixing and Inhibition of Virus–Cell Fusion

Cited by 55 publications

References 90 publications

A GxxxG-like Motif within HIV-1 Fusion Peptide Is Critical to Its Immunosuppressant Activity, Structure, and Interaction with the Transmembrane Domain of the T-cell Receptor

A GxxxG-like Motif within HIV-1 Fusion Peptide Is Critical to Its Immunosuppressant Activity, Structure, and Interaction with the Transmembrane Domain of the T-cell Receptor

Dissociation of the trimeric gp41 ectodomain at the lipid–water interface suggests an active role in HIV-1 Env-mediated membrane fusion

Efficient replication of a paramyxovirus independent of full zippering of the fusion protein six-helix bundle domain

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