Cryo-EM structure of full-length HIV-1 Env bound with the Fab of antibody PG16

Pan, Junhua; Peng, Hanqin; Chen, Bing

doi:10.1101/730333

Cited by 7 publications

(9 citation statements)

References 59 publications

(95 reference statements)

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“…Indeed, the structure of a PGT151-bound full-length Env trimer that was purified by detergent solubilization of cell surface expressed gp160 demonstrated contacts between the topological layers of gp120 and the gp41 three-helix bundle consistent with the conclusion that the mutations were targeting an allosteric network common to both the native Env and engineered SOSIPs 47 . Recent structures of the full length, detergent-solubilized gp160 SOSIP trimers in complex with PGT145 or PG16 showed a similar overall structure of the SOSIP Env, and also showed similar gp120 topological layer contacts with the gp41 3-helix bundle 48,49 , lending further support for the generality of these contacts and the proposed mechanism of Env allostery. Based on these results, we propose a mechanism by which the HIV-1 Env transitions from the prefusion closed state to a fully open, fusion-competent state through a series of sequential steps (Fig.…”

Section: -Rearrangementmentioning

confidence: 75%

Disruption of the HIV-1 Envelope allosteric network blocks CD4-induced rearrangements

Henderson

Zhou

et al. 2020

Nat Commun

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The trimeric HIV-1 Envelope protein (Env) mediates viral-host cell fusion via a network of conformational transitions, with allosteric elements in each protomer orchestrating host receptor-induced exposure of the co-receptor binding site and fusion elements. To understand the molecular details of this allostery, here, we introduce Env mutations aimed to prevent CD4-induced rearrangements in the HIV-1 BG505 Env trimer. Binding analysis and single−molecule Förster Resonance Energy Transfer confirm that these mutations prevent CD4-induced transitions of the HIV-1 Env. Structural analysis by single−particle cryoelectron microscopy performed on the BG505 SOSIP mutant Env proteins shows rearrangements in the gp120 topological layer contacts with gp41. Displacement of a conserved tryptophan (W571) from its typical pocket in these Env mutants renders the Env insensitive to CD4 binding. These results reveal the critical function of W571 as a conformational switch in Env allostery and receptor-mediated viral entry and provide insights on Env conformation that are relevant for vaccine design.

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Section: -Rearrangementmentioning

confidence: 75%

Disruption of the HIV-1 Envelope allosteric network blocks CD4-induced rearrangements

Henderson

Zhou

et al. 2020

Nat Commun

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“…45 Indeed, the structure of a PGT151-bound full length Env trimer that was purified by detergent solubilization of cell surface expressed gp160 demonstrated contacts between the topological layers of gp120 and the gp41 three-helix bundle consistent with the conclusion that the mutations were targeting an allosteric network common to both the native Env and engineered SOSIPs. 46 Recent structures of the full length, detergent-solubilized gp160 SOSIP trimers in complex with PGT145 or PG16 showed a similar overall structure of the SOSIP Env, and also showed similar gp120 topological layer contacts with the gp41 3-helix bundle 47,48 , lending further support for the generality of these contacts and the proposed mechanism of Env allostery. Based on these results, we propose a sequential mechanism by which the HIV-1 Env transitions from the prefusion closed state to a fully open, fusion-competent state through a series of sequential steps (figure 7D).…”

Section: Discussionmentioning

confidence: 67%

Disruption of the HIV-1 Envelope allosteric network blocks CD4-induced rearrangements

Henderson

Zhou

et al. 2019

Preprint

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30The trimeric HIV-1 Envelope protein (Env) mediates viral-host cell fusion via a network of 31 conformational transitions, with allosteric elements in each protomer orchestrating host 32 receptor-induced exposure of the co-receptor binding site and fusion elements. To 33 understand the molecular details of this allostery, we introduced Env mutations aimed to 34 prevent CD4-induced rearrangements in the HIV-1 BG505 Env trimer. Binding analysis 35 performed on the soluble ectodomain BG505 SOSIP Env trimers, cell-surface expressed 36 BG505 full-length trimers and single-molecule Förster Resonance Energy Transfer 37 (smFRET) performed on the full-length virion-bound Env confirmed that these mutations 38 prevented CD4-induced transitions of the HIV-1 Env. Structural analysis by single-39 particle cryo-electron microscopy performed on the BG505 SOSIP mutant Env proteins 40 revealed rearrangements in the gp120 topological layer contacts with gp41. Specifically, 41 a conserved tryptophan at position 571 (W571) was displaced from its typical pocket at 42 the interface of gp120 topological layers 1 and 2 by lysine 567, disrupting key gp120-43 gp41 contacts and rendering the Env insensitive to CD4 binding. Vector based analysis 44 of closed Env SOSIP structures revealed the newly designed trimers exhibited a 45 quaternary structure distinct from that typical of SOSIPs and residing near a cluster of 46 Env trimers bound to vaccine-induced fusion peptide-directed antibodies (vFP Mabs). 47These results reveal the critical function of W571 as a conformational switch in Env 48 allostery and receptor-mediated viral entry and provide insights on Env conformation that 49 are relevant for vaccine design.50 51 52 53 54Host cell entry of HIV-1 is accomplished by the envelope glycoprotein (Env) spike. HIV-1 55Env is a trimer of heterodimers comprised of gp120 and gp41 protomers, and exists in a 56 metastable conformation capable of transitioning from a prefusion closed configuration to a 57 fusion-competent open state upon triggering by CD4. 1,2 The C-terminal gp41 domain contains a 58 single transmembrane helix and the membrane fusion elements of the trimer. 3-5 The gp12059 segment binds the primary receptor CD4, triggering conformational changes leading to the 60 binding of co-receptor CCR5/CXCR4 that causes global rearrangements in the trimer structure 61 leading to viral and cell membrane fusion and gp120 shedding. 6-8 While many studies have 62 sought to understand the nature of the communication between the CD4 binding site, the 63 coreceptor binding site and the fusogenic elements of the HIV-1 Env, a complete understanding 64 of the allosteric mechanism and metastability in HIV-1 Env remains lacking. 65The design of a soluble, stabilized ectodomain Env (SOSIP), containing an engineered 66 gp120 to gp41 disulfide (SOS) and an HR1 helix breaking I to P mutation, has revealed 67 structural details regarding broadly neutralizing antibody (bnAb) epitopes and as an immunogen 68 has induced autologous neutralizing antibodies. 2,9 The...

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“…Focused refinement of this internal third layer revealed a distinct structure that clearly resembles a lattice formed by the capsid domain (CA) of immature Gag polyprotein (Figure 2B and Figure S4D) (Schur, Hagen et al 2015). Thus, structures of trimeric Env ectodomain (Pan, Peng et al 2020) and hexameric Gag-CA (Schur, Hagen et al 2015) were fitted as rigid bodies into corresponding densities in the averaged map (Figure 2C). No clear density for the Env TMD-CTD was observed in the averaged structure, even though the TMD is seen in individual raw tomograms (Figure 2C), suggesting that the TMD is not strictly aligned with the ectodomain or Gag-CA.…”

Section: Env Structure From Immature Particles Reveal Interactions With Gagmentioning

confidence: 96%

“…Apart from hVLP-Env, this bend in HR2 helix has only been observed in the full-length, detergentsolubilized Env structure derived from strain 92UG037.8 (Pan, Peng et al 2020). In the presence of membrane, we observe that the thin stalks, corresponding to Env residues 654-664, form a tripod that elevates the ectodomain ~10 Å above the membrane (Figure 3B).…”

Section: Differences In Gp41's Terminal Hr2 Helix and Stalk Influence Mper Surface Exposurementioning

confidence: 97%

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Cryo-ET of HIV reveals Env positioning on Gag lattice and structural variation among Env trimers

Prasad

Leaman

Lovendahl

et al. 2021

Preprint

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HIV-1 Env mediates viral entry into host cells and is the sole target for neutralizing antibodies. However, Env structure and organization in its native virion context has eluded detailed characterization. Here we used cryo-electron tomography to analyze Env in mature and immature HIV-1 particles. Immature particles showed distinct Env positioning relative to the underlying Gag lattice, providing insights into long-standing questions about Env incorporation. A 9.1A sub-tomogram averaged reconstruction of virion-bound Env in conjunction with structural mass spectrometry revealed unexpected features, including a variable central core of the gp41 subunit, heterogeneous glycosylation between protomers plus a flexible stalk that allows Env tilting and variable exposure of neutralizing epitopes. Together, our results provide an integrative understanding of HIV assembly and structural variation in Env antigen presentation.

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Cryo-EM structure of full-length HIV-1 Env bound with the Fab of antibody PG16

Cited by 7 publications

References 59 publications

Disruption of the HIV-1 Envelope allosteric network blocks CD4-induced rearrangements

Disruption of the HIV-1 Envelope allosteric network blocks CD4-induced rearrangements

Disruption of the HIV-1 Envelope allosteric network blocks CD4-induced rearrangements

Cryo-ET of HIV reveals Env positioning on Gag lattice and structural variation among Env trimers

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