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Nangarlia A, Hassen FF, Canziani G, Bandi P, Talukder C, Zhang F, Krauth D, Gary EN, Weiner DB, Bieniasz P, Navas-Martin S, O'Keefe BR, Ang CG, Chaiken I. Irreversible Inactivation of SARS-CoV-2 by Lectin Engagement with Two Glycan Clusters on the Spike Protein. Biochemistry 2023; 62:2115-2127. [PMID: 37341186 PMCID: PMC10663058 DOI: 10.1021/acs.biochem.3c00109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/22/2023]
Abstract
Host cell infection by SARS-CoV-2, similar to that by HIV-1, is driven by a conformationally metastable and highly glycosylated surface entry protein complex, and infection by these viruses has been shown to be inhibited by the mannose-specific lectins cyanovirin-N (CV-N) and griffithsin (GRFT). We discovered in this study that CV-N not only inhibits SARS-CoV-2 infection but also leads to irreversibly inactivated pseudovirus particles. The irreversibility effect was revealed by the observation that pseudoviruses first treated with CV-N and then washed to remove all soluble lectin did not recover infectivity. The infection inhibition of SARS-CoV-2 pseudovirus mutants with single-site glycan mutations in spike suggested that two glycan clusters in S1 are important for both CV-N and GRFT inhibition: one cluster associated with the RBD (receptor binding domain) and the second with the S1/S2 cleavage site. We observed lectin antiviral effects with several SARS-CoV-2 pseudovirus variants, including the recently emerged omicron, as well as a fully infectious coronavirus, therein reflecting the breadth of lectin antiviral function and the potential for pan-coronavirus inactivation. Mechanistically, observations made in this work indicate that multivalent lectin interaction with S1 glycans is likely a driver of the lectin infection inhibition and irreversible inactivation effect and suggest the possibility that lectin inactivation is caused by an irreversible conformational effect on spike. Overall, lectins' irreversible inactivation of SARS-CoV-2, taken with their breadth of function, reflects the therapeutic potential of multivalent lectins targeting the vulnerable metastable spike before host cell encounter.
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Affiliation(s)
- Aakansha Nangarlia
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, Pennsylvania 19102, United States
| | - Farah Fazloon Hassen
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
| | - Gabriela Canziani
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
| | - Praneeta Bandi
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
| | - Choya Talukder
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
| | - Fengwen Zhang
- Laboratory of Retrovirology, The Rockefeller University, New York, New York 10065, United States
- Howard Hughes Medical Institute, The Rockefeller University, New York, New York 10065, United States
| | - Douglas Krauth
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
| | - Ebony N Gary
- The Vaccine and Immunotherapy Center, Wistar Institute, Philadelphia, Pennsylvania 19104, United States
| | - David B Weiner
- The Vaccine and Immunotherapy Center, Wistar Institute, Philadelphia, Pennsylvania 19104, United States
| | - Paul Bieniasz
- Laboratory of Retrovirology, The Rockefeller University, New York, New York 10065, United States
- Howard Hughes Medical Institute, The Rockefeller University, New York, New York 10065, United States
| | - Sonia Navas-Martin
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
- Department of Microbiology and Immunology, Center for Molecular Virology & Translational Neuroscience, Institute for Molecular Medicine & Infectious Disease, Philadelphia, Pennsylvania 19102, United States
| | - Barry R O'Keefe
- Molecular Targets Program, Center for Cancer Research, National Cancer Institute, NIH, Frederick, Maryland 21702, United States
- Natural Products Branch, Developmental Therapeutics Program, Division of Cancer Treatment and Diagnosis, National Cancer Institute, Frederick, Maryland 21702, United States
| | - Charles G Ang
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
| | - Irwin Chaiken
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
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Recent research results have converted gp120 binders to a therapeutic option for the treatment of HIV-1 infection. A medicinal chemistry point of view. Eur J Med Chem 2021; 229:114078. [PMID: 34992041 DOI: 10.1016/j.ejmech.2021.114078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 12/16/2021] [Accepted: 12/22/2021] [Indexed: 11/21/2022]
Abstract
Current therapeutic armamentarium for treatment of HIV-1 infection is based on the use of highly active antiretroviral therapy that, unfortunately, does not act as a curative remedy. Moreover, duration of the therapy often results in lack of compliance with the consequent emergence of multidrug resistance. Finally, drug toxicity issues also arise during treatments. In the attempt to achieve a curative effect, in addition to invest substantial resources in finding new anti-HIV-1 agents and in optimizing antiviral lead compounds and drugs currently available, additional efforts should be done to deplete viral reservoir located within host CD4+ T cells. Gp120 binders represent a class of compounds able to affect the interactions between viral envelope proteins and host CD4, thus avoiding virus-to-cell attachment and fusion, and the consequent viral entry into host cells. This review summarizes the efforts done in the last five years to design new gp120 binders, that finally culminated in the approval of fostemsavir as an anti-HIV-1 drug.
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Zhang S, Holmes AP, Dick A, Rashad AA, Enríquez Rodríguez L, Canziani GA, Root MJ, Chaiken IM. Altered Env conformational dynamics as a mechanism of resistance to peptide-triazole HIV-1 inactivators. Retrovirology 2021; 18:31. [PMID: 34627310 PMCID: PMC8501640 DOI: 10.1186/s12977-021-00575-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 09/20/2021] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND We previously developed drug-like peptide triazoles (PTs) that target HIV-1 Envelope (Env) gp120, potently inhibit viral entry, and irreversibly inactivate virions. Here, we investigated potential mechanisms of viral escape from this promising class of HIV-1 entry inhibitors. RESULTS HIV-1 resistance to cyclic (AAR029b) and linear (KR13) PTs was obtained by dose escalation in viral passaging experiments. High-level resistance for both inhibitors developed slowly (relative to escape from gp41-targeted C-peptide inhibitor C37) by acquiring mutations in gp120 both within (Val255) and distant to (Ser143) the putative PT binding site. The similarity in the resistance profiles for AAR029b and KR13 suggests that the shared IXW pharmacophore provided the primary pressure for HIV-1 escape. In single-round infectivity studies employing recombinant virus, V255I/S143N double escape mutants reduced PT antiviral potency by 150- to 3900-fold. Curiously, the combined mutations had a much smaller impact on PT binding affinity for monomeric gp120 (four to ninefold). This binding disruption was entirely due to the V255I mutation, which generated few steric clashes with PT in molecular docking. However, this minor effect on PT affinity belied large, offsetting changes to association enthalpy and entropy. The escape mutations had negligible effect on CD4 binding and utilization during entry, but significantly altered both binding thermodynamics and inhibitory potency of the conformationally-specific, anti-CD4i antibody 17b. Moreover, the escape mutations substantially decreased gp120 shedding induced by either soluble CD4 or AAR029b. CONCLUSIONS Together, the data suggest that the escape mutations significantly modified the energetic landscape of Env's prefusogenic state, altering conformational dynamics to hinder PT-induced irreversible inactivation of Env. This work therein reveals a unique mode of virus escape for HIV-1, namely, resistance by altering the intrinsic conformational dynamics of the Env trimer.
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Affiliation(s)
- Shiyu Zhang
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA, USA
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, USA
| | - Andrew P Holmes
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA, USA
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Alexej Dick
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Adel A Rashad
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA, USA
| | | | - Gabriela A Canziani
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Michael J Root
- Department of Microbial Infection and Immunity, The Ohio State University College of Medicine, OH, Columbus, USA.
| | - Irwin M Chaiken
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA, USA.
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Ang CG, Carter E, Haftl A, Zhang S, Rashad AA, Kutzler M, Abrams CF, Chaiken IM. Peptide Triazole Thiol Irreversibly Inactivates Metastable HIV-1 Env by Accessing Conformational Triggers Intrinsic to Virus-Cell Entry. Microorganisms 2021; 9:1286. [PMID: 34204725 PMCID: PMC8231586 DOI: 10.3390/microorganisms9061286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 06/03/2021] [Accepted: 06/09/2021] [Indexed: 11/16/2022] Open
Abstract
KR13, a peptide triazole thiol previously established to inhibit HIV-1 infection and cause virus lysis, was evaluated by flow cytometry against JRFL Env-presenting cells to characterize induced Env and membrane transformations leading to irreversible inactivation. Transiently transfected HEK293T cells were preloaded with calcein dye, treated with KR13 or its thiol-blocked analogue KR13b, fixed, and stained for gp120 (35O22), MPER (10E8), 6-helix-bundle (NC-1), immunodominant loop (50-69), and fusion peptide (VRC34.01). KR13 induced dose-dependent transformations of Env and membrane characterized by transient poration, MPER exposure, and 6-helix-bundle formation (analogous to native fusion events), but also reduced immunodominant loop and fusion peptide exposure. Using a fusion peptide mutant (V504E), we found that KR13 transformation does not require functional fusion peptide for poration. In contrast, simultaneous treatment with fusion inhibitor T20 alongside KR13 prevented membrane poration and MPER exposure, showing that these events require 6-helix-bundle formation. Based on these results, we formulated a model for PTT-induced Env transformation portraying how, in the absence of CD4/co-receptor signaling, PTT may provide alternate means of perturbing the metastable Env-membrane complex, and inducing fusion-like transformation. In turn, the results show that such transformations are intrinsic to Env and can be diverted for irreversible inactivation of the protein complex.
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Affiliation(s)
- Charles Gotuaco Ang
- Department of Biochemistry and Molecular Biology, College of Medicine, Drexel University, Philadelphia, PA 19102, USA; (E.C.); (A.H.); (S.Z.); (A.A.R.)
- School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, PA 19102, USA
| | - Erik Carter
- Department of Biochemistry and Molecular Biology, College of Medicine, Drexel University, Philadelphia, PA 19102, USA; (E.C.); (A.H.); (S.Z.); (A.A.R.)
- Departments of Medicine and Microbiology and Immunology, College of Medicine, Drexel University, Philadelphia, PA 19102, USA;
| | - Ann Haftl
- Department of Biochemistry and Molecular Biology, College of Medicine, Drexel University, Philadelphia, PA 19102, USA; (E.C.); (A.H.); (S.Z.); (A.A.R.)
- Department of Chemistry, College of Arts and Sciences, Drexel University, Philadelphia, PA 19102, USA
| | - Shiyu Zhang
- Department of Biochemistry and Molecular Biology, College of Medicine, Drexel University, Philadelphia, PA 19102, USA; (E.C.); (A.H.); (S.Z.); (A.A.R.)
- School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, PA 19102, USA
| | - Adel A. Rashad
- Department of Biochemistry and Molecular Biology, College of Medicine, Drexel University, Philadelphia, PA 19102, USA; (E.C.); (A.H.); (S.Z.); (A.A.R.)
| | - Michele Kutzler
- Departments of Medicine and Microbiology and Immunology, College of Medicine, Drexel University, Philadelphia, PA 19102, USA;
| | - Cameron F. Abrams
- Department of Chemical and Biological Engineering, College of Engineering, Drexel University, Philadelphia, PA 19102, USA;
| | - Irwin M. Chaiken
- Department of Biochemistry and Molecular Biology, College of Medicine, Drexel University, Philadelphia, PA 19102, USA; (E.C.); (A.H.); (S.Z.); (A.A.R.)
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Nascimento da Silva LC, Mendonça JSP, de Oliveira WF, Batista KLR, Zagmignan A, Viana IFT, Dos Santos Correia MT. Exploring lectin-glycan interactions to combat COVID-19: Lessons acquired from other enveloped viruses. Glycobiology 2021; 31:358-371. [PMID: 33094324 PMCID: PMC7665446 DOI: 10.1093/glycob/cwaa099] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Revised: 08/30/2020] [Accepted: 09/26/2020] [Indexed: 01/08/2023] Open
Abstract
The emergence of a new human coronavirus (SARS-CoV-2) has imposed great pressure on the health system worldwide. The presence of glycoproteins on the viral envelope opens a wide range of possibilities for application of lectins to address some urgent problems involved in this pandemic. In this work, we discuss the potential contributions of lectins from non-mammalian sources in the development of several fields associated with viral infections, most notably COVID-19. We review the literature on the use of non-mammalian lectins as a therapeutic approach against members of the Coronaviridae family, including recent advances in strategies of protein engineering to improve their efficacy. The applications of lectins as adjuvants for antiviral vaccines are also discussed. Finally, we present some emerging strategies employing lectins for the development of biosensors, microarrays, immunoassays and tools for purification of viruses from whole blood. Altogether, the data compiled in this review highlights the importance of structural studies aiming to improve our knowledge about the basis of glycan recognition by lectins and its repercussions in several fields, providing potential solutions for complex aspects that are emerging from different health challenges.
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Affiliation(s)
- Luís Cláudio Nascimento da Silva
- Programa de Pós-graduação em Biologia Microbiana, Laboratório de Patogenicidade Bacteriana, Universidade CEUMA, São Luís 65075-120, Brazil.,Programa de Pós-graduação em Biodiversidade e Biotecnologia da Amazônia Legal, Laboratório de Patogenicidade Bacteriana, Universidade CEUMA, São Luís 65075-120, Brazil
| | - Juliana Silva Pereira Mendonça
- Programa de Pós-graduação em Biologia Microbiana, Laboratório de Patogenicidade Bacteriana, Universidade CEUMA, São Luís 65075-120, Brazil
| | - Weslley Felix de Oliveira
- Departamento de Bioquímica, Centro de Biociências, Universidade Federal de Pernambuco, Recife 50.670-901, Brazil
| | - Karla Lílian Rodrigues Batista
- Programa de Pós-graduação em Biodiversidade e Biotecnologia da Amazônia Legal, Laboratório de Patogenicidade Bacteriana, Universidade CEUMA, São Luís 65075-120, Brazil
| | - Adrielle Zagmignan
- Programa de Pós-graduação em Biodiversidade e Biotecnologia da Amazônia Legal, Laboratório de Patogenicidade Bacteriana, Universidade CEUMA, São Luís 65075-120, Brazil
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Gaffney A, Nangarlia A, Ang CG, Gossert S, Rashad Ahmed AA, Hossain MA, Abrams CF, Smith AB, Chaiken I. HIV-1 Env-Dependent Cell Killing by Bifunctional Small-Molecule/Peptide Conjugates. ACS Chem Biol 2021; 16:440-442. [PMID: 33535751 DOI: 10.1021/acschembio.1c00039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Althea Gaffney
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Aakansha Nangarlia
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Charles G. Ang
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
| | - Steven Gossert
- Department of Chemical and Biological Engineering, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Adel Ahmed Rashad Ahmed
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
| | - Md Alamgir Hossain
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
| | - Cameron F. Abrams
- Department of Chemical and Biological Engineering, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Amos B. Smith
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Irwin Chaiken
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
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Gaffney A, Nangarlia A, Ang CG, Gossert S, Rashad Ahmed AA, Hossain MA, Abrams CF, Smith AB, Chaiken I. HIV-1 Env-Dependent Cell Killing by Bifunctional Small-Molecule/Peptide Conjugates. ACS Chem Biol 2021; 16:193-204. [PMID: 33410670 DOI: 10.1021/acschembio.0c00888] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A strategy has been established for the synthesis of a family of bifunctional HIV-1 inhibitor covalent conjugates with the potential to bind simultaneously to both the gp120 and gp41 subunits of the HIV-1 envelope glycoprotein trimeric complex (Env). One component of the conjugates is derived from BNM-III-170, a small-molecule CD4 mimic that binds to gp120. The second component, comprised of the peptide DKWASLWNW ("Trp3"), was derived from the N-terminus of the HIV-1 gp41 Membrane Proximal External Region (MPER) and found previously to bind to the gp41 subunit of Env. The resulting bifunctional conjugates were shown to inhibit virus cell infection with low micromolar potency and to induce lysis of the HIV-1 virion. Crucially, virolysis was found to be dependent on the covalent linkage of the BNM-III-170 and Trp3 domains, as coadministration of a mixture of the un-cross-linked components proved to be nonlytic. However, a significant magnitude of lytic activity was observed in Env-negative and other control pseudoviruses, suggesting parallel mechanisms of action of the conjugates involving Env interaction and direct membrane disruption. Computational modeling suggested strong membrane-binding activity of BNM-III-170, which may underly the nonspecific virolytic effects of the conjugates. To investigate the scope of the membrane effect, cell-based cytotoxicity and membrane permeability assays were performed employing flow cytometry. Here, we observed a dose-dependent and specific cytotoxic effect on HIV-1 Env-expressing cells by the small-molecule bifunctional inhibitor. Most importantly, Env-negative cells were not susceptible to the cytotoxic effect upon exposure to this construct at concentrations where cell-killing effects were observed for Env-positive cells. Computational structural modeling supports a mechanism in which the bifunctional inhibitors bind to the gp120 and gp41 subunits in tandem in open-state Env trimers and induce relative motion of the gp120 subunits consistent with models of Env inactivation. This observation supports the idea that the cell-killing effect of the small-molecule bifunctional inhibitor is due to specific Env conformational triggering. This work lays important groundwork to advance a small-molecule bifunctional inhibitor approach for eliminating Env-expressing infected cells and the eradication of HIV-1.
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Affiliation(s)
- Althea Gaffney
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Aakansha Nangarlia
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Charles G. Ang
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
| | - Steven Gossert
- Department of Chemical and Biological Engineering, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Adel Ahmed Rashad Ahmed
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
| | - Md Alamgir Hossain
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
| | - Cameron F. Abrams
- Department of Chemical and Biological Engineering, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Amos B. Smith
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Irwin Chaiken
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, United States
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8
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Parajuli B, Acharya K, Nangarlia A, Zhang S, Parajuli B, Dick A, Ngo B, Abrams CF, Chaiken I. Identification of a glycan cluster in gp120 essential for irreversible HIV-1 lytic inactivation by a lectin-based recombinantly engineered protein conjugate. Biochem J 2020; 477:4263-4280. [PMID: 33057580 DOI: 10.1042/bcj20200495] [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: 06/23/2020] [Revised: 10/13/2020] [Accepted: 10/15/2020] [Indexed: 11/17/2022]
Abstract
We previously discovered a class of recombinant lectin conjugates, denoted lectin DLIs ('dual-acting lytic inhibitors') that bind to the HIV-1 envelope (Env) protein trimer and cause both lytic inactivation of HIV-1 virions and cytotoxicity of Env-expressing cells. To facilitate mechanistic investigation of DLI function, we derived the simplified prototype microvirin (MVN)-DLI, containing an MVN domain that binds high-mannose glycans in Env, connected to a DKWASLWNW sequence (denoted 'Trp3') derived from the membrane-associated region of gp41. The relatively much stronger affinity of the lectin component than Trp3 argues that the lectin functions to capture Env to enable Trp3 engagement and consequent Env membrane disruption and virolysis. The relatively simplified engagement pattern of MVN with Env opened up the opportunity, pursued here, to use recombinant glycan knockout gp120 variants to identify the precise Env binding site for MVN that drives DLI engagement and lysis. Using mutagenesis combined with a series of biophysical and virological experiments, we identified a restricted set of residues, N262, N332 and N448, all localized in a cluster on the outer domain of gp120, as the essential epitope for MVN binding. By generating these mutations in the corresponding HIV-1 virus, we established that the engagement of this glycan cluster with the lectin domain of MVN*-DLI is the trigger for DLI-derived virus and cell inactivation. Beyond defining the initial encounter step for lytic inactivation, this study provides a guide to further elucidate DLI mechanism, including the stoichiometry of Env trimer required for function, and downstream DLI optimization.
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Affiliation(s)
- Bibek Parajuli
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102, U.S.A
| | - Kriti Acharya
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102, U.S.A
| | - Aakansha Nangarlia
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102, U.S.A
| | - Shiyu Zhang
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102, U.S.A
| | - Bijay Parajuli
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102, U.S.A
| | - Alexej Dick
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102, U.S.A
| | - Brendon Ngo
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102, U.S.A
| | - Cameron F Abrams
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102, U.S.A
- Department of Chemical and Biological Engineering, Drexel University, Philadelphia, PA 19104, U.S.A
| | - Irwin Chaiken
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102, U.S.A
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