Cryo-EM structure of a native, fully glycosylated, cleaved HIV-1 envelope trimer

Lee, Jeong Hyun; Ozorowski, Gabriel; Ward, Andrew B.

doi:10.1126/science.aad2450

Cited by 415 publications

(641 citation statements)

References 63 publications

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“…1 A and B). The BG505 Env in this complex adopts a conformation that is more open than the closed conformation in crystal and EM structures of Env trimers (8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19), but less open than the conformation in low-resolution sCD4-bound Env structures (4-7) (Figs. 2 A and B and 3A) and an ∼9-Å cryo-EM reconstruction of the KN1144 SOSIP.681 soluble trimer bound to 17b in the absence of sCD4 (7).…”

Section: Resultsmentioning

confidence: 98%

“…Single-particle electron microscopy (EM) structures of recombinant native-like soluble Env gp140 trimers (SOSIPs) confirmed that they can adopt the same closed and open architectures as virion-bound Env trimers (5-7), thus the SOSIP substitutions (introduction of a disulfide bond linking gp120 to gp41 and an Ile→Pro mutation in gp41; ref. The closed conformation of HIV-1 Env is stabilized by interactions at the trimer apex mediated by the gp120 V1V2 loop (8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19). In the closed state, the V1V2 region shields the binding site for the coreceptor on the V3 loop (11, 16), but V1V2 interactions with V3 cannot be maintained when the gp120 protomers rotate and separate to create the CD4-bound open conformation.…”

mentioning

confidence: 99%

“…6) do not appear to prevent transition to the open state. Despite the plethora of recent crystal and EM structures at atomic and nearatomic resolutions of closed Env trimers, most in complex with broadly neutralizing antibodies (bNAbs) (8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19), only low-resolution structures derived from cryo-electron tomography of HIV-1 virions have been available for sCD4-bound open Env trimers (4)(5)(6)(7).…”

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confidence: 99%

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Cryo-EM structure of a CD4-bound open HIV-1 envelope trimer reveals structural rearrangements of the gp120 V1V2 loop

Wang

Cohen

Galimidi

et al. 2016

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

143

200

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The HIV-1 envelope (Env) glycoprotein, a trimer of gp120-gp41 heterodimers, relies on conformational flexibility to function in fusing the viral and host membranes. Fusion is achieved after gp120 binds to CD4, the HIV-1 receptor, and a coreceptor, capturing an open conformational state in which the fusion machinery on gp41 gains access to the target cell membrane. In the well-characterized closed Env conformation, the gp120 V1V2 loops interact at the apex of the Env trimer. Less is known about the structure of the open CD4-bound state, in which the V1V2 loops must rearrange and separate to allow access to the coreceptor binding site. We identified two anti-HIV-1 antibodies, the coreceptor mimicking antibody 17b and the gp120-gp41 interface-spanning antibody 8ANC195, that can be added as Fabs to a soluble native-like Env trimer to stabilize it in a CD4-bound conformation. Here, we present an 8.9-Å cryo-electron microscopy structure of a BG505 Env-sCD4-17b-8ANC195 complex, which reveals large structural rearrangements in gp120, but small changes in gp41, compared with closed Env structures. The gp120 protomers are rotated and separated in the CD4-bound structure, and the three V1V2 loops are displaced by ∼40 Å from their positions at the trimer apex in closed Env to the sides of the trimer in positions adjacent to, and interacting with, the three bound CD4s. These results are relevant to understanding CD4-induced conformational changes leading to coreceptor binding and fusion, and HIV-1 Env conformational dynamics, and describe a target structure relevant to drug design and vaccine efforts.T he HIV-1 envelope (Env) glycoprotein, a trimer of gp120-gp41 heterodimers, mediates recognition of host receptors and fusion of the viral and target cell membranes (1). Structural flexibility of HIV-1 Env is required for its function in membrane fusion; thus, Env exists in multiple conformational states on the surface of virions (2). Fusion involves several steps: The gp120 portion of Env trimer first binds to the host receptor CD4 to capture a conformational state of Env that exposes the binding site for an HIV-1 coreceptor (CCR5 or CXCR4), which, in turn, leads to gp41-mediated fusion of the viral and host cell membranes. CD4-induced conformational changes within the Env trimer are incompletely understood. The binding of soluble CD4 (sCD4) produces little to no changes in the structures of gp120 cores (gp120 monomers with truncations in the N and C termini and variable V1V2 and V3 loops) (3), but results in rotation of the gp120 protomers within virion-bound Env trimers to create an open conformation distinct from the closed conformation of unliganded virion-bound trimers (4). Single-particle electron microscopy (EM) structures of recombinant native-like soluble Env gp140 trimers (SOSIPs) confirmed that they can adopt the same closed and open architectures as virion-bound Env trimers (5-7), thus the SOSIP substitutions (introduction of a disulfide bond linking gp120 to gp41 and an Ile→Pro mutation in gp41; ref. The closed co...

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Section: Resultsmentioning

confidence: 98%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Cryo-EM structure of a CD4-bound open HIV-1 envelope trimer reveals structural rearrangements of the gp120 V1V2 loop

Wang

Cohen

Galimidi

et al. 2016

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

143

200

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“…Structural studies of bNAbs bound to HIV Env trimers revealed mechanisms by which bNAbs targeting various epitopes penetrate the glycan shield to either accommodate or include N-glycans in their epitopes (Julien et al, 2013;Pancera et al, 2014;Scharf et al, 2015;Garces et al, 2015;Lee et al, 2015Lee et al, , 2016Stewart-Jones et al, 2016). However, because heterogeneous glycosylation generally prevents the formation of well ordered crystals, all HIV Env crystal structures had been solved using glycoproteins produced in exclusively high-mannose forms (Diskin et al, 2011(Diskin et al, , 2013Kwon et al, 2015;Garces et al, 2015;Julien et al, 2013;Pancera et al, 2014;Scharf et al, 2014Scharf et al, , 2015StewartJones et al, 2016;Zhou et al, 2010Zhou et al, , 2013Zhou et al, , 2015Kwong et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

X-ray and EM structures of a natively glycosylated HIV-1 envelope trimer

Gristick

Wang

Björkman

2017

Acta Crystallogr D Struct Biol

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The structural and biochemical characterization of broadly neutralizing anti-HIV-1 antibodies (bNAbs) has been essential in guiding the design of potential vaccines to prevent infection by HIV-1. While these studies have revealed critical mechanisms by which bNAbs recognize and/or accommodate N-glycans on the trimeric envelope glycoprotein (Env), they have been limited to the visualization of high-mannose glycan forms only, since heterogeneity introduced from the presence of complex glycans makes it difficult to obtain high-resolution structures. 3.5 and 3.9 Å resolution crystal structures of the HIV-1 Env trimer with fully processed and native glycosylation were solved, revealing a glycan shield of high-mannose and complex-type N-glycans that were used to define the complete epitopes of two bNAbs. Here, the refinement of the N-glycans in the crystal structures is discussed and comparisons are made with glycan densities in glycosylated Env structures derived by single-particle cryo-electron microscopy.

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“…Chu, Maltsev, Emwas, & Lorigan, 2010;Schnell & Chou, 2008). Very recently, cryo-EM is providing more structural information especially on huge membrane protein complexes (Byeon et al, 2009;Lee, Ozorowski, & Ward, 2016;X. Zhang, Jin, Fang, Hui, & Zhou, 2010).…”

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confidence: 99%

Druggability analysis of membrane proteins by DoGSiteScorer

Zhang

2017

Preprint

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Membrane proteins are the most medicinally important yet to be fully exploited pharmaceutical targets. Here druggability analyses are conducted on three different membrane proteins, namely, the human P2Y12 receptor, glycoprotein-41 that mediates the HIV-1 virus entry and membrane fusion, and phospholamban that regulates the Ca 2+ pump in cardiac muscle cells. DoGSiteScorer, a grid-based bioinfromatic technology, is able to identify the binding pockets of all three membrane proteins, and the results were in great agreements with the available crystal structure of P2Y12 receptorligand complex. This druggability analysis is especially helpful in cases where the crystal structures of membrane protein-ligand complexes are still difficult to obtain. Better understanding of the druggable pockets of membrane proteins also requires including the membrane environment.

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Cryo-EM structure of a native, fully glycosylated, cleaved HIV-1 envelope trimer

Cited by 415 publications

References 63 publications

Cryo-EM structure of a CD4-bound open HIV-1 envelope trimer reveals structural rearrangements of the gp120 V1V2 loop

Cryo-EM structure of a CD4-bound open HIV-1 envelope trimer reveals structural rearrangements of the gp120 V1V2 loop

X-ray and EM structures of a natively glycosylated HIV-1 envelope trimer

Druggability analysis of membrane proteins by DoGSiteScorer

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