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Wang K, Zhang S, Go EP, Ding H, Wang WL, Nguyen HT, Kappes JC, Desaire H, Sodroski J, Mao Y. Asymmetric conformations of cleaved HIV-1 envelope glycoprotein trimers in styrene-maleic acid lipid nanoparticles. Commun Biol 2023; 6:535. [PMID: 37202420 PMCID: PMC10195785 DOI: 10.1038/s42003-023-04916-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 05/04/2023] [Indexed: 05/20/2023] Open
Abstract
During virus entry, the pretriggered human immunodeficiency virus (HIV-1) envelope glycoprotein (Env) trimer initially transits into a default intermediate state (DIS) that remains structurally uncharacterized. Here, we present cryo-EM structures at near-atomic resolution of two cleaved full-length HIV-1 Env trimers purified from cell membranes in styrene-maleic acid lipid nanoparticles without antibodies or receptors. The cleaved Env trimers exhibited tighter subunit packing than uncleaved trimers. Cleaved and uncleaved Env trimers assumed remarkably consistent yet distinct asymmetric conformations, with one smaller and two larger opening angles. Breaking conformational symmetry is allosterically coupled with dynamic helical transformations of the gp41 N-terminal heptad repeat (HR1N) regions in two protomers and with trimer tilting in the membrane. The broken symmetry of the DIS potentially assists Env binding to two CD4 receptors-while resisting antibody binding-and promotes extension of the gp41 HR1 helical coiled-coil, which relocates the fusion peptide closer to the target cell membrane.
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Affiliation(s)
- Kunyu Wang
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing, China
- Peking-Tsinghua Joint Center for Life Science, Peking University, Beijing, China
| | - Shijian Zhang
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA, USA
- Department of Microbiology, Harvard Medical School, Boston, MA, USA
| | - Eden P Go
- Department of Chemistry, University of Kansas, Lawrence, KS, USA
| | - Haitao Ding
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Wei Li Wang
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing, China
| | - Hanh T Nguyen
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA, USA
- Department of Microbiology, Harvard Medical School, Boston, MA, USA
| | - John C Kappes
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
- Birmingham Veterans Affairs Medical Center, Research Service, Birmingham, AL, USA
| | - Heather Desaire
- Department of Chemistry, University of Kansas, Lawrence, KS, USA
| | - Joseph Sodroski
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA, USA.
- Department of Microbiology, Harvard Medical School, Boston, MA, USA.
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
| | - Youdong Mao
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing, China.
- Peking-Tsinghua Joint Center for Life Science, Peking University, Beijing, China.
- Center for Quantitative Biology, Academy of Advanced Interdisciplinary Studies, Peking University, Beijing, China.
- National Biomedical Imaging Center, Peking University, Beijing, China.
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Chandra S, Manjunath K, Asok A, Varadarajan R. Mutational scan inferred binding energetics and structure in intrinsically disordered protein CcdA. Protein Sci 2023; 32:e4580. [PMID: 36714997 PMCID: PMC9951195 DOI: 10.1002/pro.4580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 01/02/2023] [Accepted: 01/25/2023] [Indexed: 01/31/2023]
Abstract
Unlike globular proteins, mutational effects on the function of Intrinsically Disordered Proteins (IDPs) are not well-studied. Deep Mutational Scanning of a yeast surface displayed mutant library yields insights into sequence-function relationships in the CcdA IDP. The approach enables facile prediction of interface residues and local structural signatures of the bound conformation. In contrast to previous titration-based approaches which use a number of ligand concentrations, we show that use of a single rationally chosen ligand concentration can provide quantitative estimates of relative binding constants for large numbers of protein variants. This is because the extended interface of IDP ensures that energetic effects of point mutations are spread over a much smaller range than for globular proteins. Our data also provides insights into the much-debated role of helicity and disorder in partner binding of IDPs. Based on this exhaustive mutational sensitivity dataset, a rudimentary model was developed in an attempt to predict mutational effects on binding affinity of IDPs that form alpha-helical structures upon binding.
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Affiliation(s)
| | | | - Aparna Asok
- Molecular Biophysics Unit, Indian Institute of ScienceBangaloreIndia
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A facile method of mapping HIV-1 neutralizing epitopes using chemically masked cysteines and deep sequencing. Proc Natl Acad Sci U S A 2020; 117:29584-29594. [PMID: 33168755 DOI: 10.1073/pnas.2010256117] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Identification of specific epitopes targeted by neutralizing antibodies is essential to advance epitope-based vaccine design strategies. We report a facile methodology for rapid epitope mapping of neutralizing antibodies (NAbs) against HIV-1 Envelope (Env) at single-residue resolution, using Cys labeling, viral neutralization assays, and deep sequencing. This was achieved by the generation of a library of Cys mutations in Env glycoprotein on the viral surface, covalent labeling of the Cys residues using a Cys-reactive label that masks epitope residues, followed by infection of the labeled mutant virions in mammalian cells in the presence of NAbs. Env gene sequencing from NAb-resistant viruses was used to accurately delineate epitopes for the NAbs VRC01, PGT128, and PGT151. These agreed well with corresponding experimentally determined structural epitopes previously inferred from NAb:Env structures. HIV-1 infection is associated with complex and polyclonal antibody responses, typically composed of multiple antibody specificities. Deconvoluting the epitope specificities in a polyclonal response is a challenging task. We therefore extended our methodology to map multiple specificities of epitopes targeted in polyclonal sera, elicited in immunized animals as well as in an HIV-1-infected elite neutralizer capable of neutralizing tier 3 pseudoviruses with high titers. The method can be readily extended to other viruses for which convenient reverse genetics or lentiviral surface display systems are available.
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