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Principal Investigator: Bing Chen
Organization: BOSTON CHILDREN'S HOSPITAL
Fiscal Year: 2024
Award: $772,175
Funding agency: National Institute of Allergy and Infectious Diseases
Summary
Virus entry begins with the first encounter between the virus and the cell surface and ends with delivery of the
contents of the virus into the host cell. HIV-1 membrane fusion is the first key delivery step, mediated by the
virus-encoded envelope glycoprotein [Env; trimeric (gp160)3 cleaved to (gp120/gp41)3], which belongs to the
group of class I viral fusion proteins including influenza hemagglutinin, SARS-CoV-2 spike protein and Ebola
glycoprotein. A mature Env spike has three copies each of noncovalently-associated receptor-binding subunit
gp120 and fusion subunit gp41. Sequential binding of gp120 to the primary receptor CD4 and a coreceptor
(chemokine receptor CCR5 or CXCR4) leads to large, irreversible structural rearrangements in gp41, which drive
fusion. This picture, derived largely from structural studies of the soluble fragments and from cellular studies with
inhibitors and antibodies, is still incomplete because it lacks extension to a high-resolution picture of the complete
Env trimer in the context of a lipid-bilayer membrane, which is the substrate of the fusion reaction. We have
determined by NMR the structures of the HIV-1 Env transmembrane domain (TMD), membrane proximal external
region (MPER), and cytoplasmic tail (CT) in bicelles that mimic lipid bilayers. These regions all form well-ordered,
trimeric clusters in a lipid bilayer. Disruption of any of them can reduce membrane fusion efficiency and alter the
antigenic structure of the entire Env, suggesting that they have structural and functional roles in fusion and in
trimer conformational stabilization. Very recently, we have completed a high-resolution structure of the intact
SARS-CoV-2 postfusion spike in membrane, showing how the functionally critical membrane-interacting regions
interact with membrane and with each other. These findings are the basis of our overall hypothesis that that
structures of the HIV-1 fusion complex either alone or bound with fusion inhibitors in membrane will reveal new
structural features of the membrane-interacting regions and substantially advance our mechanistic
understanding of the viral fusion and its inhibition, thereby informing future development of intervention
strategies. We will apply advanced technologies in cryogenic electron microscopy (cryo-EM) and tomography
(cryo-ET) to study structural and functional properties of the HIV-1 fusion complex, as reconstituted in
membranes and on the surface of a virus particle. We will also investigate molecular mechanisms of HIV-1
inhibition by two distinct types of fusion inhibitors. Our goal is a "molecular movie" of HIV-1 fusion, to inform
development of new intervention strategies. We propose the following Specific Aims to address our hypothesis:
1) We will determine structure of the HIV-1 fusion complex containing intact Env, CD4 and CCR5 in the context
of a lipid bilayer. 2) We will investigate molecular mechanism of HIV-1 fusion inhibition by anti-CD4 antibody
ibalizumab. 3) We will dissect mechanism of action of small-molecule fusion inhibitors targeting the MPER of
HIV-1 Env.
Terms: <2019 novel corona virus><2019 novel coronavirus><2019-nCoV><2019-nCoV S protein><2019-nCoV spike glycoprotein><2019-nCoV spike protein><Address><Antibodies><Binding><Binding Sites><C-C CKR-5><C-C CKR-5 Gene><C-C Chemokine Receptor Type 5><C-C Chemokine Receptor Type 5 Gene><CC Chemokine Receptor 5><CC-CKR-5><CC-CKR-5 Gene><CC-CKR5><CCCKR5><CCCKR5 Gene><CCR-5><CCR-5 Gene><CCR5><CCR5 Protein><CCR5 Receptors><CCR5 gene><CD195 Antigen><CD195 Antigen Gene><CD4 Antigens><CD4 Molecule><CD4 Protein><CD4 Receptors><CHEMR13><CHEMR13 Gene><CKR-5><CKR-5 Gene><CKR5><CKR5 Gene><CKR5 Receptors><CMKBR5><CMKBR5 Gene><COVID-19 S protein><COVID-19 spike><COVID-19 spike glycoprotein><COVID-19 spike protein><COVID-19 virus><COVID19 virus><CXC-R4><CXCR-4><CXCR4><CXCR4 gene><Cell Body><Cell surface><Cells><Chemokine (C-C Motif) Receptor 5><Chemokine (C-C) Receptor 5><Chemokine (C-C) Receptor 5 Gene><Chemokine Receptor Gene><Clinical Treatment Moab><CoV-2><CoV2><Combining Site><Complex><Cryo-electron Microscopy><Cryo-electron tomography><Cryoelectron Microscopy><Cytoplasmic Domain><Cytoplasmic Tail><D2S201E><Detergents><Development><Ebola><Electron Cryomicroscopy><Electron Microscopy><Envelope Protein><FB22><FDA approved><Future><Glycoproteins><Goals><HIV Envelope Glycoprotein gp120><HIV Envelope Protein gp120><HIV env Protein gp120><HIV-1><HIV-1 Fusion Co-Receptor><HIV-1 Fusion Co-Receptor Gene><HIV-I><HIV1><HM89><HSY3RR><HTLV-III gp120><Human><Human Immunodeficiency Virus Type 1><Human immunodeficiency virus 1><Infection><Infection prevention><Influenza HA><Influenza Hemagglutinin><Intervention><Intervention Strategies><LAP3><LCR1><LESTR><Length><Lipid Bilayers><Lipids><Mediating><Membrane><Membrane Fusion><Metabolic Glycosylation><Micelles><Modern Man><Molecular><Molecular Configuration><Molecular Conformation><Molecular Interaction><Molecular Mechanisms of Action><Molecular Stereochemistry><Monoclonal Antibodies><NPY3R><NPYR><NPYRL><NPYY3R><OKT4 antigen><Pilot Projects><Prevent infection><Process><Property><Reaction><Reactive Site><Receptor Protein><Resolution><Role><SARS corona virus 2><SARS-CO-V2><SARS-COVID-2><SARS-CoV-2><SARS-CoV-2 S><SARS-CoV-2 S protein><SARS-CoV-2 spike><SARS-CoV-2 spike glycoprotein><SARS-CoV-2 spike protein><SARS-CoV2><SARS-associated corona virus 2><SARS-associated coronavirus 2><SARS-coronavirus-2><SARS-related corona virus 2><SARS-related coronavirus 2><SARSCoV2><Series><Severe Acute Respiratory Coronavirus 2><Severe Acute Respiratory Distress Syndrome CoV 2><Severe Acute Respiratory Distress Syndrome Corona Virus 2><Severe Acute Respiratory Distress Syndrome Coronavirus 2><Severe Acute Respiratory Syndrome CoV 2><Severe Acute Respiratory Syndrome-associated coronavirus 2><Severe Acute Respiratory Syndrome-related coronavirus 2><Severe acute respiratory syndrome associated corona virus 2><Severe acute respiratory syndrome coronavirus 2><Severe acute respiratory syndrome coronavirus 2 S protein><Severe acute respiratory syndrome coronavirus 2 spike glycoprotein><Severe acute respiratory syndrome coronavirus 2 spike protein><Severe acute respiratory syndrome related corona virus 2><Structure><Surface><Surface CD4 Receptors><System><T4 molecule><TM Domain><Technology><Therapeutic><Therapeutic Agents><Transmembrane Domain><Transmembrane Region><Viral><Viral Fusion Proteins><Viral Vaccines><Virion><Virus><Virus Inhibitors><Virus Particle><Visualization><Wuhan coronavirus><chemokine receptor><conformation><conformational><conformational state><conformationally><conformations><coronavirus disease 2019 S protein><coronavirus disease 2019 spike glycoprotein><coronavirus disease 2019 spike protein><coronavirus disease 2019 virus><coronavirus disease-19 virus><cryo-EM><cryo-EM tomography><cryoEM><cryoEM tomography><cryoelectron tomography><cryogenic electron microscopy><design><designing><develop a vaccine><develop therapy><develop vaccines><development of a vaccine><developmental><electron cryo-tomography><electron tomography><env Antigens><env Gene Products><env Polyproteins><env Protein><flu HA><flu hemagglutinin><glycosylation><gp120><gp120 ENV Glycoprotein><gp120(HIV)><gp160><hCoV19><helper T lymphocyte marker><improved><influenza viral HA><influenza viral hemagglutinin><influenza virus HA><influenza virus hemagglutinin><inhibitor><insight><intervention development><interventional strategy><lipid bilayer membrane><mAbs><membrane assembly><membrane structure><monoclonal Abs><movie><nCoV2><nanodisk><neutralizing antibody><novel><particle><pilot study><receptor><receptor binding><receptor bound><reconstitute><reconstitution><resolutions><small molecule><social role><spike proteins on SARS-CoV-2><structural biology><therapy development><treatment development><vaccine development><viral inhibitor>