1
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Zhou J, Wang L, Liu X, Gai Y, Dong M, Wang C, Ali MM, Ye M, Yu X, Hu L. Glycan-Imprinted Nanoparticle as Artificial Neutralizing Antibody for Efficient HIV-1 Recognition and Inhibition. NANO LETTERS 2024; 24:4423-4432. [PMID: 38568019 DOI: 10.1021/acs.nanolett.4c00142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/18/2024]
Abstract
The HIV-1 envelope is a heavily glycosylated class 1 trimeric fusion protein responsible for viral entry into CD4+ immune cells. Developing neutralizing antibodies against the specific envelope glycans is an alternative method for antiviral therapies. This work presents the first-ever development and characterization of artificial neutralizing antibodies using molecular imprinting technology to recognize and bind to the envelope protein of HIV-1. The prepared envelope glycan-imprinted nanoparticles (GINPs) can successfully prevent HIV-1 from infecting target cells by shielding the glycans on the envelope protein. In vitro experiments showed that GINPs have strong affinity toward HIV-1 (Kd = 36.7 ± 2.2 nM) and possess high anti-interference and specificity. GINPs demonstrate broad inhibition activity against both tier 1 and tier 2 HIV-1 strains with a pM-level IC50 and exhibit a significant inhibitory effect on long-term viral replication by more than 95%. The strategy provides a promising method for the inhibition and therapy of HIV-1 infection.
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Affiliation(s)
- Juntao Zhou
- Center for Supramolecular Chemical Biology, National Engineering Laboratory of AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, Jilin 130012, China
| | - Libian Wang
- Center for Supramolecular Chemical Biology, National Engineering Laboratory of AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, Jilin 130012, China
| | - Xiaoyan Liu
- CAS Key Laboratory of Separation Sciences for Analytical Chemistry, National Chromatographic R&A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences Dalian, Liaoning 116023, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yanxin Gai
- Center for Supramolecular Chemical Biology, National Engineering Laboratory of AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, Jilin 130012, China
| | - Mingming Dong
- CAS Key Laboratory of Separation Sciences for Analytical Chemistry, National Chromatographic R&A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences Dalian, Liaoning 116023, China
| | - Chu Wang
- Center for Supramolecular Chemical Biology, National Engineering Laboratory of AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, Jilin 130012, China
| | - Muhammad Mujahid Ali
- Center for Supramolecular Chemical Biology, National Engineering Laboratory of AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, Jilin 130012, China
| | - Mingliang Ye
- CAS Key Laboratory of Separation Sciences for Analytical Chemistry, National Chromatographic R&A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences Dalian, Liaoning 116023, China
| | - Xianghui Yu
- Center for Supramolecular Chemical Biology, National Engineering Laboratory of AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, Jilin 130012, China
| | - Lianghai Hu
- Center for Supramolecular Chemical Biology, National Engineering Laboratory of AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, Jilin 130012, China
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2
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Heindel DW, Figueroa Acosta DM, Goff M, Yengo CK, Jan M, Liu X, Wang XH, Petrova MI, Zhang M, Sagar M, Barnette P, Pandey S, Hessell AJ, Chan KW, Kong XP, Chen BK, Mahal LK, Bensing BA, Hioe CE. HIV-1 interaction with an O-glycan-specific bacterial lectin enhances virus infectivity and resistance to neutralization by antibodies. RESEARCH SQUARE 2024:rs.3.rs-2596269. [PMID: 36824869 PMCID: PMC9949255 DOI: 10.21203/rs.3.rs-2596269/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Bacteria dysbiosis has been associated with an increased risk of HIV-1 transmission and acquisition. The prevalent idea is that bacteria dysbiosis compromises mucosal integrity and promotes inflammatory conditions to cause recruitment and activation of immune cells that harbor or are targeted by HIV-1. However, it is also possible that HIV-1 directly binds bacteria or bacterial products to impact virus infectivity and transmissibility. This study evaluated HIV-1 interactions with bacteria through glycan-binding lectins. The Streptococcal Siglec-like lectin SLBR-N, which is part of the fimbriae shrouding the bacteria surface and recognizes α2,3 sialyated O-linked glycans, was noted for its ability to enhance HIV-1 infectivity in the context of cell-free infection and cell-to-cell transfer. Enhancing effects were recapitulated with O-glycan-binding plant lectins, signifying the importance of O-glycans. Conversely, N-glycan-binding bacterial lectins FimH and Msl had no effect. SLBR-N was demonstrated to capture and transfer infectious HIV-1 virions, bind to O-glycans on HIV-1 Env, and increase HIV-1 resistance to broadly neutralizing antibodies targeting different regions of Env. Hence, this study highlights the potential contribution of O-glycans in promoting HIV-1 infection through the exploitation of O-glycan-binding lectins from commensal bacteria at the mucosa.
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Affiliation(s)
- Daniel W Heindel
- Divison of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Dania M Figueroa Acosta
- Divison of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Marisa Goff
- Divison of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Clauvis Kunkeng Yengo
- Divison of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Muzafar Jan
- Divison of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Present address: Department of Biochemistry, Government Degree College Handwara, University of Kashmir, Jammu & Kashmir, India
| | - Xiaomei Liu
- Divison of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Xiao-Hong Wang
- VA New York Harbor Healthcare System-Manhattan, New York, New York, United States of America
| | - Mariya I Petrova
- Department of Bioscience Engineering, University of Antwerp, Antwerp, Belgium
- Present address: Microbiome Insights and Probiotics Consultancy, Karlovo, Bulgaria
| | - Mo Zhang
- Department of Medicine, Boston University Chobanian & Avedisian School of Medicine, Boston, MA, USA
| | - Manish Sagar
- Department of Medicine, Boston University Chobanian & Avedisian School of Medicine, Boston, MA, USA
- Department of Virology, Immunology and Microbiology, Boston University Chobanian & Avedisian School of Medicine, Boston, USA
| | - Phillip Barnette
- Division of Pathobiology and Immunology, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR, USA
| | - Shilpi Pandey
- Division of Pathobiology and Immunology, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR, USA
| | - Ann J Hessell
- Division of Pathobiology and Immunology, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR, USA
| | - Kun-Wei Chan
- Department of Biochemistry and Molecular Pharmacology New York University Grossman School of Medicine, New York, NY, USA
| | - Xiang-Peng Kong
- Department of Biochemistry and Molecular Pharmacology New York University Grossman School of Medicine, New York, NY, USA
| | - Benjamin K Chen
- Divison of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Lara K Mahal
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Barbara A Bensing
- Department of Medicine, San Francisco Veterans Affairs Medical Center and University of California, San Francisco, CA, USA
| | - Catarina E Hioe
- Divison of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- James J. Peters VA Medical Center, Bronx, USA
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3
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Heindel DW, Figueroa Acosta DM, Goff M, Yengo CK, Jan M, Liu X, Wang XH, Petrova MI, Zhang M, Sagar M, Barnette P, Pandey S, Hessell AJ, Chan KW, Kong XP, Chen BK, Mahal LK, Bensing BA, Hioe CE. HIV-1 interaction with an O-glycan-specific bacterial lectin enhances virus infectivity and resistance to neutralization by antibodies. RESEARCH SQUARE 2024:rs.3.rs-2596269. [PMID: 36824869 PMCID: PMC9949255 DOI: 10.21203/rs.3.rs-2596269/v2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 08/14/2024]
Abstract
Bacteria dysbiosis has been associated with an increased risk of HIV-1 transmission and acquisition. The prevalent idea is that bacteria dysbiosis compromises mucosal integrity and promotes inflammatory conditions to cause recruitment and activation of immune cells that harbor or are targeted by HIV-1. However, it is also possible that HIV-1 directly binds bacteria or bacterial products to impact virus infectivity and transmissibility. This study evaluated HIV-1 interactions with bacteria through glycan-binding lectins. The Streptococcal Siglec-like lectin SLBR-N, which is part of the fimbriae shrouding the bacteria surface and recognizes α2,3 sialyated O-linked glycans, was noted for its ability to enhance HIV-1 infectivity in the context of cell-free infection and cell-to-cell transfer. Enhancing effects were recapitulated with O-glycan-binding plant lectins, signifying the importance of O-glycans. Conversely, N-glycan-binding bacterial lectins FimH and Msl had no effect. SLBR-N was demonstrated to capture and transfer infectious HIV-1 virions, bind to O-glycans on HIV-1 Env, and increase HIV-1 resistance to broadly neutralizing antibodies targeting different regions of Env. Hence, this study highlights the potential contribution of O-glycans in promoting HIV-1 infection through the exploitation of O-glycan-binding lectins from commensal bacteria at the mucosa.
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Affiliation(s)
- Daniel W Heindel
- Divison of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Dania M Figueroa Acosta
- Divison of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Marisa Goff
- Divison of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Clauvis Kunkeng Yengo
- Divison of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Muzafar Jan
- Divison of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Present address: Department of Biochemistry, Government Degree College Handwara, University of Kashmir, Jammu & Kashmir, India
| | - Xiaomei Liu
- Divison of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Xiao-Hong Wang
- VA New York Harbor Healthcare System-Manhattan, New York, New York, United States of America
| | - Mariya I Petrova
- Department of Bioscience Engineering, University of Antwerp, Antwerp, Belgium
- Present address: Microbiome Insights and Probiotics Consultancy, Karlovo, Bulgaria
| | - Mo Zhang
- Department of Medicine, Boston University Chobanian & Avedisian School of Medicine, Boston, MA, USA
| | - Manish Sagar
- Department of Medicine, Boston University Chobanian & Avedisian School of Medicine, Boston, MA, USA
- Department of Virology, Immunology and Microbiology, Boston University Chobanian & Avedisian School of Medicine, Boston, USA
| | - Phillip Barnette
- Division of Pathobiology and Immunology, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR, USA
| | - Shilpi Pandey
- Division of Pathobiology and Immunology, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR, USA
| | - Ann J Hessell
- Division of Pathobiology and Immunology, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR, USA
| | - Kun-Wei Chan
- Department of Biochemistry and Molecular Pharmacology New York University Grossman School of Medicine, New York, NY, USA
| | - Xiang-Peng Kong
- Department of Biochemistry and Molecular Pharmacology New York University Grossman School of Medicine, New York, NY, USA
| | - Benjamin K Chen
- Divison of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Lara K Mahal
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Barbara A Bensing
- Department of Medicine, San Francisco Veterans Affairs Medical Center and University of California, San Francisco, CA, USA
| | - Catarina E Hioe
- Divison of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- James J. Peters VA Medical Center, Bronx, USA
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4
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Lennemann NJ, Corliss L, Maury W. Modification of N-Linked Glycan Sites in Viral Glycoproteins. Methods Mol Biol 2024; 2762:27-41. [PMID: 38315358 DOI: 10.1007/978-1-0716-3666-4_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2024]
Abstract
Post-translational modification of proteins by the addition of sugar chains, or glycans, is a functionally important hallmark of proteins trafficked through the secretory system. These proteins are termed glycoproteins. Glycans are known to be important for initiating signaling through binding of cell surface receptors, facilitating protein folding, and maintaining protein stability. For pathogens, glycans can also mask vulnerable protein regions from neutralizing antibodies. Thus, there is a need to develop methods to decipher the role of specific glycans attached to proteins in order to understand their biological role. Here, we describe established methods for identifying glycosylated residues and understanding their role in protein synthesis and function using viral glycoproteins as a model.
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Affiliation(s)
- Nicholas J Lennemann
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA.
| | - Lochlain Corliss
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Wendy Maury
- Department of Microbiology and Immunology, University of Iowa, Iowa City, IA, USA
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5
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Rocamora F, Peralta AG, Shin S, Sorrentino J, Wu MYM, Toth EA, Fuerst TR, Lewis NE. Glycosylation shapes the efficacy and safety of diverse protein, gene and cell therapies. Biotechnol Adv 2023; 67:108206. [PMID: 37354999 PMCID: PMC11168894 DOI: 10.1016/j.biotechadv.2023.108206] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 05/26/2023] [Accepted: 06/20/2023] [Indexed: 06/26/2023]
Abstract
Over recent decades, therapeutic proteins have had widespread success in treating a myriad of diseases. Glycosylation, a near universal feature of this class of drugs, is a critical quality attribute that significantly influences the physical properties, safety profile and biological activity of therapeutic proteins. Optimizing protein glycosylation, therefore, offers an important avenue to developing more efficacious therapies. In this review, we discuss specific examples of how variations in glycan structure and glycoengineering impacts the stability, safety, and clinical efficacy of protein-based drugs that are already in the market as well as those that are still in preclinical development. We also highlight the impact of glycosylation on next generation biologics such as T cell-based cancer therapy and gene therapy.
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Affiliation(s)
- Frances Rocamora
- Department of Pediatrics, University of California, San Diego, La Jolla, CA 92093, USA
| | - Angelo G Peralta
- Department of Pediatrics, University of California, San Diego, La Jolla, CA 92093, USA
| | - Seunghyeon Shin
- Department of Pediatrics, University of California, San Diego, La Jolla, CA 92093, USA
| | - James Sorrentino
- Department of Pediatrics, University of California, San Diego, La Jolla, CA 92093, USA
| | - Mina Ying Min Wu
- Department of Pediatrics, University of California, San Diego, La Jolla, CA 92093, USA; Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Eric A Toth
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850, USA
| | - Thomas R Fuerst
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850, USA; Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
| | - Nathan E Lewis
- Department of Pediatrics, University of California, San Diego, La Jolla, CA 92093, USA; Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA.
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6
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Ogharandukun E, Tewolde W, Damtae E, Wang S, Ivanov A, Kumari N, Nekhai S, Chandran PL. Establishing Rules for Self-Adhesion and Aggregation of N-Glycan Sugars Using Virus Glycan Shields. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:13769-13783. [PMID: 33186493 PMCID: PMC7798417 DOI: 10.1021/acs.langmuir.0c01953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The surfaces of cells and pathogens are covered with short polymers of sugars known as glycans. Complex N-glycans have a core of three mannose sugars with distal repeats of N-acetylglucosamine and galactose sugars terminating with sialic acid (SA). Long-range tough and short-range brittle self-adhesions were observed between SA and mannose residues, respectively, in ill-defined artificial monolayers. We investigated if and how these adhesions translate when the residues are presented in N-glycan architecture with SA at the surface and mannose at the core and with other glycan sugars. Two pseudotyped viruses with complex N-glycan shields were brought together in force spectroscopy (FS). At higher ramp rates, slime-like adhesions were observed between the shields, whereas Velcro-like adhesions were observed at lower rates. The higher approach rates compress the virus as a whole, and the self-adhesion between the surface SA is sampled. At the lower ramp rates, however, the complex glycan shield is penetrated and adhesion from the mannose core is accessed. The slime-like and Velcro-like adhesions were lost when SA and mannose were cleaved, respectively. While virus self-adhesion in forced contact was modulated by glycan penetrability, the self-aggregation of the freely diffusing virus was only determined by the surface sugar. Mannose-terminal viruses self-aggregated in solution, and SA-terminal ones required Ca2+ ions to self-aggregate. Viruses with galactose or N-acetylglucosamine surfaces did not self-aggregate, irrespective of whether or not a mannose core was present below the N-acetylglucosamine surface. Well-defined rules appear to govern the self-adhesion and -aggregation of N-glycosylated surfaces, regardless of whether the sugars are presented in an ill-defined monolayer, or N-glycan, or even polymer architecture.
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7
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Berndsen ZT, Chakraborty S, Wang X, Cottrell CA, Torres JL, Diedrich JK, López CA, Yates JR, van Gils MJ, Paulson JC, Gnanakaran S, Ward AB. Visualization of the HIV-1 Env glycan shield across scales. Proc Natl Acad Sci U S A 2020; 117:28014-28025. [PMID: 33093196 PMCID: PMC7668054 DOI: 10.1073/pnas.2000260117] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The dense array of N-linked glycans on the HIV-1 envelope glycoprotein (Env), known as the "glycan shield," is a key determinant of immunogenicity, yet intrinsic heterogeneity confounds typical structure-function analysis. Here, we present an integrated approach of single-particle electron cryomicroscopy (cryo-EM), computational modeling, and site-specific mass spectrometry (MS) to probe glycan shield structure and behavior at multiple levels. We found that dynamics lead to an extensive network of interglycan interactions that drive the formation of higher-order structure within the glycan shield. This structure defines diffuse boundaries between buried and exposed protein surface and creates a mapping of potentially immunogenic sites on Env. Analysis of Env expressed in different cell lines revealed how cryo-EM can detect subtle changes in glycan occupancy, composition, and dynamics that impact glycan shield structure and epitope accessibility. Importantly, this identified unforeseen changes in the glycan shield of Env obtained from expression in the same cell line used for vaccine production. Finally, by capturing the enzymatic deglycosylation of Env in a time-resolved manner, we found that highly connected glycan clusters are resistant to digestion and help stabilize the prefusion trimer, suggesting the glycan shield may function beyond immune evasion.
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Affiliation(s)
- Zachary T Berndsen
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037
- The International AIDS Vaccine Initiative Neutralizing Antibody Center, The Scripps Research Institute, La Jolla, CA 92037
- Scripps Consortium For HIV/AIDS Vaccine Development, The Scripps Research Institute, La Jolla, CA 92037
| | - Srirupa Chakraborty
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, NM 87545
- Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM 87545
| | - Xiaoning Wang
- The International AIDS Vaccine Initiative Neutralizing Antibody Center, The Scripps Research Institute, La Jolla, CA 92037
- Scripps Consortium For HIV/AIDS Vaccine Development, The Scripps Research Institute, La Jolla, CA 92037
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037
| | - Christopher A Cottrell
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037
- The International AIDS Vaccine Initiative Neutralizing Antibody Center, The Scripps Research Institute, La Jolla, CA 92037
- Scripps Consortium For HIV/AIDS Vaccine Development, The Scripps Research Institute, La Jolla, CA 92037
| | - Jonathan L Torres
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037
| | - Jolene K Diedrich
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037
| | - Cesar A López
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, NM 87545
| | - John R Yates
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037
| | - Marit J van Gils
- Department of Medical Microbiology, Amsterdam University Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
| | - James C Paulson
- The International AIDS Vaccine Initiative Neutralizing Antibody Center, The Scripps Research Institute, La Jolla, CA 92037
- Scripps Consortium For HIV/AIDS Vaccine Development, The Scripps Research Institute, La Jolla, CA 92037
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA 92037
| | | | - Andrew B Ward
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037;
- The International AIDS Vaccine Initiative Neutralizing Antibody Center, The Scripps Research Institute, La Jolla, CA 92037
- Scripps Consortium For HIV/AIDS Vaccine Development, The Scripps Research Institute, La Jolla, CA 92037
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8
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An Engineered Microvirin Variant with Identical Structural Domains Potently Inhibits Human Immunodeficiency Virus and Hepatitis C Virus Cellular Entry. Viruses 2020; 12:v12020199. [PMID: 32054060 PMCID: PMC7077325 DOI: 10.3390/v12020199] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 01/22/2020] [Indexed: 02/08/2023] Open
Abstract
Microvirin (MVN) is one of the human immunodeficiency virus (HIV-1) entry inhibitor lectins, which consists of two structural domains sharing 35% sequence identity and contrary to many other antiviral lectins, it exists as a monomer. In this study, we engineered an MVN variant, LUMS1, consisting of two domains with 100% sequence identity, thereby reducing the chemical heterogeneity, which is a major factor in eliciting immunogenicity. We determined carbohydrate binding of LUMS1 through NMR chemical shift perturbation and tested its anti-HIV activity in single-round infectivity assay and its anti-hepatitis C virus (HCV) activity in three different assays including HCVcc, HCVpp, and replicon assays. We further investigated the effect of LUMS1 on the activation of T helper (Th) and B cells through flow cytometry. LUMS1 showed binding to α(1-2)mannobiose, the minimum glycan epitope of MVN, potently inhibited HIV-1 and HCV with EC50 of 37.2 and 45.3 nM, respectively, and showed negligible cytotoxicity with CC50 > 10 µM against PBMCs, Huh-7.5 and HepG2 cells, and 4.9 µM against TZM-bl cells. LUMS1 did not activate Th cells, and its stimulatory effect on B cells was markedly less as compared to MVN. Together, with these effects, LUMS1 represents a potential candidate for the development of antiviral therapies.
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9
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Rathore U, Purwar M, Vignesh VS, Das R, Kumar AA, Bhattacharyya S, Arendt H, DeStefano J, Wilson A, Parks C, La Branche CC, Montefiori DC, Varadarajan R. Bacterially expressed HIV-1 gp120 outer-domain fragment immunogens with improved stability and affinity for CD4-binding site neutralizing antibodies. J Biol Chem 2018; 293:15002-15020. [PMID: 30093409 DOI: 10.1074/jbc.ra118.005006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Indexed: 12/20/2022] Open
Abstract
Protein minimization is an attractive approach for designing vaccines against rapidly evolving pathogens such as human immunodeficiency virus, type 1 (HIV-1), because it can help in focusing the immune response toward conserved conformational epitopes present on complex targets. The outer domain (OD) of HIV-1 gp120 contains epitopes for a large number of neutralizing antibodies and therefore is a primary target for structure-based vaccine design. We have previously designed a bacterially expressed outer-domain immunogen (ODEC) that bound CD4-binding site (CD4bs) ligands with 3-12 μm affinity and elicited a modest neutralizing antibody response in rabbits. In this study, we have optimized ODEC using consensus sequence design, cyclic permutation, and structure-guided mutations to generate a number of variants with improved yields, biophysical properties, stabilities, and affinities (KD of 10-50 nm) for various CD4bs targeting broadly neutralizing antibodies, including the germline-reverted version of the broadly neutralizing antibody VRC01. In contrast to ODEC, the optimized immunogens elicited high anti-gp120 titers in rabbits as early as 6 weeks post-immunization, before any gp120 boost was given. Following two gp120 boosts, sera collected at week 22 showed cross-clade neutralization of tier 1 HIV-1 viruses. Using a number of different prime/boost combinations, we have identified a cyclically permuted OD fragment as the best priming immunogen, and a trimeric, cyclically permuted gp120 as the most suitable boosting molecule among the tested immunogens. This study also provides insights into some of the biophysical correlates of improved immunogenicity.
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Affiliation(s)
- Ujjwal Rathore
- From the Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India 560012
| | - Mansi Purwar
- From the Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India 560012
| | | | - Raksha Das
- From the Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India 560012
| | - Aditya Arun Kumar
- From the Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India 560012
| | - Sanchari Bhattacharyya
- From the Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India 560012
| | - Heather Arendt
- the International AIDS Vaccine Initiative, Brooklyn, New York 11226, and
| | - Joanne DeStefano
- the International AIDS Vaccine Initiative, Brooklyn, New York 11226, and
| | - Aaron Wilson
- the International AIDS Vaccine Initiative, Brooklyn, New York 11226, and
| | - Christopher Parks
- the International AIDS Vaccine Initiative, Brooklyn, New York 11226, and
| | - Celia C La Branche
- the Department of Surgery, Duke University Medical Center, Durham, North Carolina 27707
| | - David C Montefiori
- the Department of Surgery, Duke University Medical Center, Durham, North Carolina 27707
| | - Raghavan Varadarajan
- From the Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India 560012,
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10
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Rathore U, Saha P, Kesavardhana S, Kumar AA, Datta R, Devanarayanan S, Das R, Mascola JR, Varadarajan R. Glycosylation of the core of the HIV-1 envelope subunit protein gp120 is not required for native trimer formation or viral infectivity. J Biol Chem 2017; 292:10197-10219. [PMID: 28446609 DOI: 10.1074/jbc.m117.788919] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 04/26/2017] [Indexed: 01/05/2023] Open
Abstract
The gp120 subunit of the HIV-1 envelope (Env) protein is heavily glycosylated at ∼25 glycosylation sites, of which ∼7-8 are located in the V1/V2 and V3 variable loops and the others in the remaining core gp120 region. Glycans partially shield Env from recognition by the host immune system and also are believed to be indispensable for proper folding of gp120 and for viral infectivity. Previous attempts to alter glycosylation sites in Env typically involved mutating the glycosylated asparagine residues to structurally similar glutamines or alanines. Here, we confirmed that such mutations at multiple glycosylation sites greatly diminish viral infectivity and result in significantly reduced binding to both neutralizing and non-neutralizing antibodies. Therefore, using an alternative approach, we combined evolutionary information with structure-guided design and yeast surface display to produce properly cleaved HIV-1 Env variants that lack all 15 core gp120 glycans, yet retain conformational integrity and multiple-cycle viral infectivity and bind to several broadly neutralizing antibodies (bNAbs), including trimer-specific antibodies and a germline-reverted version of the bNAb VRC01. Our observations demonstrate that core gp120 glycans are not essential for folding, and hence their likely primary role is enabling immune evasion. We also show that our glycan removal approach is not strain restricted. Glycan-deficient Env derivatives can be used as priming immunogens because they should engage and activate a more divergent set of germlines than fully glycosylated Env. In conclusion, these results clarify the role of core gp120 glycosylation and illustrate a general method for designing glycan-free folded protein derivatives.
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Affiliation(s)
- Ujjwal Rathore
- From the Molecular Biophysics Unit, Indian Institute of Science, 560012 Bangalore, India
| | - Piyali Saha
- From the Molecular Biophysics Unit, Indian Institute of Science, 560012 Bangalore, India
| | - Sannula Kesavardhana
- From the Molecular Biophysics Unit, Indian Institute of Science, 560012 Bangalore, India
| | - Aditya Arun Kumar
- From the Molecular Biophysics Unit, Indian Institute of Science, 560012 Bangalore, India
| | - Rohini Datta
- From the Molecular Biophysics Unit, Indian Institute of Science, 560012 Bangalore, India
| | | | - Raksha Das
- From the Molecular Biophysics Unit, Indian Institute of Science, 560012 Bangalore, India
| | - John R Mascola
- the Vaccine Research Center, NIAID, National Institutes of Health, Bethesda, Maryland 20814, and
| | - Raghavan Varadarajan
- From the Molecular Biophysics Unit, Indian Institute of Science, 560012 Bangalore, India, .,the Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, 560064 Bangalore, India
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11
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Goodsell DS. Illustrating the machinery of life: viruses. BIOCHEMISTRY AND MOLECULAR BIOLOGY EDUCATION : A BIMONTHLY PUBLICATION OF THE INTERNATIONAL UNION OF BIOCHEMISTRY AND MOLECULAR BIOLOGY 2012; 40:291-296. [PMID: 22987549 DOI: 10.1002/bmb.20636] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Data from electron microscopy, X-ray crystallography, and biophysical analysis are used to create illustrations of viruses in their cellular context. This report describes the scientific data and artistic methods used to create three illustrations: a depiction of the poliovirus lifecycle, budding of influenza virus from a cell surface, and a mature HIV particle in blood serum.
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Affiliation(s)
- David S Goodsell
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
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12
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Depetris RS, Julien JP, Khayat R, Lee JH, Pejchal R, Katpally U, Cocco N, Kachare M, Massi E, David KB, Cupo A, Marozsan AJ, Olson WC, Ward AB, Wilson IA, Sanders RW, Moore JP. Partial enzymatic deglycosylation preserves the structure of cleaved recombinant HIV-1 envelope glycoprotein trimers. J Biol Chem 2012; 287:24239-54. [PMID: 22645128 DOI: 10.1074/jbc.m112.371898] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The trimeric envelope glycoprotein complex (Env) is the focus of vaccine development programs aimed at generating protective humoral responses to human immunodeficiency virus type 1 (HIV-1). N-Linked glycans, which constitute almost half of the molecular mass of the external Env domains, produce considerable structural heterogeneity and are a major impediment to crystallization studies. Moreover, by shielding the peptide backbone, glycans can block attempts to generate neutralizing antibodies against a substantial subset of potential epitopes when Env proteins are used as immunogens. Here, we describe the partial deglycosylation of soluble, cleaved recombinant Env trimers by inhibition of the synthesis of complex N-glycans during Env production, followed by treatment with glycosidases under conditions that preserve Env trimer integrity. The partially deglycosylated trimers are stable, and neither abnormally sensitive to proteolytic digestion nor prone to aggregation. Moreover, the deglycosylated trimers retain or increase their ability to bind CD4 and antibodies that are directed to conformational epitopes, including the CD4-binding site and the V3 region. However, as expected, they do not react with glycan-dependent antibodies 2G12 and PGT123, or the C-type lectin receptor DC-SIGN. Electron microscopic analysis shows that partially deglycosylated trimers have a structure similar to fully glycosylated trimers, indicating that removal of glycans does not substantially perturb the structural integrity of the trimer. The glycan-depleted Env trimers should be useful for structural and immunogenicity studies.
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Affiliation(s)
- Rafael S Depetris
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York 10065, USA
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13
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Kanwal S, Mahmood T. Evolutionary pattern of Asian HIV-1 subtype B from 1990 to 2007: in silico analysis based on envelop protein. ScientificWorldJournal 2012; 2012:978917. [PMID: 22645495 PMCID: PMC3354753 DOI: 10.1100/2012/978917] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Accepted: 12/07/2011] [Indexed: 11/26/2022] Open
Abstract
HIV-1 envelop gene is a major target for vaccine development. Envelop protein and its V3 loop is shown to be important determinant of HIV-1 pathogenecity. Herein, the evolutionary pattern of most prevalent HIV-1 subtype B in Asia is determined by analyzing envelop protein and V3 domain based on the 40 randomly selected sequences of HIV-1 from database (Los Alamos), divided into four groups since 1990–2007. Construction of envelop protein phylogeny by using MEGA 5 exhibit the active mutation pattern, increase in potential N-glycosylation sites which were predicted by using online software SignalP-NN. An online available tool Drawgram was used for multiple sequence alignment (MSA) of HIV-1 subtype B envelop region and V3 loop while the alignment was rechecked by using CLUSTAL W and further was analyzed for GPGX motif and conserved region in V3 loop. Variation at fourth position of the GPGX motif and 60% conservation was found in V3 loop. Hence, this diversifying pattern of envelop protein in the Asia formulates the HIV-1 strains more pathogenic during the period of 17 years. These findings might help in understanding significant structural and functional constrains of the mutant viral strains and ultimately in vaccine development.
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Affiliation(s)
- Sobia Kanwal
- Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad 45320, Pakistan
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14
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Gold manno-Glyconanoparticles for Intervening in HIV gp120 Carbohydrate-Mediated Processes. Methods Enzymol 2012; 509:21-40. [DOI: 10.1016/b978-0-12-391858-1.00002-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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15
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Pashov A, Garimalla S, Monzavi-Karbassi B, Kieber-Emmons T. Carbohydrate targets in HIV vaccine research: lessons from failures. Immunotherapy 2011; 1:777-94. [PMID: 20636023 DOI: 10.2217/imt.09.44] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Learning from the successes of other vaccines that enhance natural and existing protective responses to pathogens, the current effort in HIV vaccine research is directed toward inducing cytotoxic responses. Nevertheless, antibodies are fundamental players in vaccine development and are still considered in the context of passive specific immunotherapy of HIV, especially since several broadly neutralizing monoclonals are available. Special interest is directed toward antibodies binding to the glycan array on gp120 since they have the potential of broader reactivity and cross-clade neutralizing capacity. Humoral responses to carbohydrate antigens have proven effective against other pathogens, why not HIV? The variability of the epitope targets on HIV may not be the only problem to developing active or passive immunotherapeutic strategies. The dynamics of the infected immune system leads to ambiguous effects of most of the effector mechanisms calling for new approaches; some may already be available, while others are in the making.
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Affiliation(s)
- Anastas Pashov
- Department of Pathology & Winthrop P Rockefeller Cancer Institute, University of Arkansas for Medical Sciences, 4301 West Markham St, #824 Little Rock, AR 72205, USA
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16
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Wang L, Qin Y, Ilchenko S, Bohon J, Shi W, Cho MW, Takamoto K, Chance MR. Structural analysis of a highly glycosylated and unliganded gp120-based antigen using mass spectrometry. Biochemistry 2010; 49:9032-45. [PMID: 20825246 DOI: 10.1021/bi1011332] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Structural characterization of the HIV-1 envelope protein gp120 is very important for providing an understanding of the protein's immunogenicity and its binding to cell receptors. So far, the crystallographic structure of gp120 with an intact V3 loop (in the absence of a CD4 coreceptor or antibody) has not been determined. The third variable region (V3) of the gp120 is immunodominant and contains glycosylation signatures that are essential for coreceptor binding and entry of the virus into T-cells. In this study, we characterized the structure of the outer domain of gp120 with an intact V3 loop (gp120-OD8) purified from Drosophila S2 cells utilizing mass spectrometry-based approaches. We mapped the glycosylation sites and calculated the glycosylation occupancy of gp120-OD8; 11 sites from 15 glycosylation motifs were determined as having high-mannose or hybrid glycosylation structures. The specific glycan moieties of nine glycosylation sites from eight unique glycopeptides were determined by a combination of ECD and CID MS approaches. Hydroxyl radical-mediated protein footprinting coupled with mass spectrometry analysis was employed to provide detailed information about protein structure of gp120-OD8 by directly identifying accessible and hydroxyl radical-reactive side chain residues. Comparison of gp120-OD8 experimental footprinting data with a homology model derived from the ligated CD4-gp120-OD8 crystal structure revealed a flexible V3 loop structure in which the V3 tip may provide contacts with the rest of the protein while residues in the V3 base remain solvent accessible. In addition, the data illustrate interactions between specific sugar moieties and amino acid side chains potentially important to the gp120-OD8 structure.
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Affiliation(s)
- Liwen Wang
- Center for Proteomics and Bioinformatics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA
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17
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Bhattacharyya S, Rajan RE, Swarupa Y, Rathore U, Verma A, Udaykumar R, Varadarajan R. Design of a non-glycosylated outer domain-derived HIV-1 gp120 immunogen that binds to CD4 and induces neutralizing antibodies. J Biol Chem 2010; 285:27100-27110. [PMID: 20558728 PMCID: PMC2930709 DOI: 10.1074/jbc.m110.152272] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Indexed: 11/06/2022] Open
Abstract
The outer domain (OD) of the HIV-1 envelope glycoprotein gp120 is an important target for vaccine design as it contains a number of conserved epitopes, including a large fraction of the CD4 binding site. Attempts to design OD-based immunogens in the past have met with little success. We report the design and characterization of an Escherichia coli-expressed OD-based immunogen (OD(EC)), based on the sequence of the HxBc2 strain. The OD(EC)-designed immunogen lacks the variable loops V1V2 and V3 and incorporates 11 designed mutations at the interface of the inner and the outer domains of gp120. Biophysical studies showed that OD(EC) is folded and protease-resistant, whereas OD(EC) lacking the designed mutations is highly aggregation-prone. In contrast to previously characterized OD constructs, OD(EC) bound CD4 and the broadly neutralizing antibody b12 but not the non-neutralizing antibodies b6 and F105. Upon immunization in rabbits, OD(EC) was highly immunogenic, and the sera showed measurable neutralization for four subtype B and one subtype C virus including two b12-resistant viruses. In contrast, sera from rabbits immunized with gp120 did not neutralize any of the viruses. OD(EC) is the first example of a gp120 fragment-based immunogen that yields significant neutralizing antibodies.
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Affiliation(s)
| | - Roshan Elizabeth Rajan
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P. O., Bangalore 560 064, India
| | - Yalla Swarupa
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P. O., Bangalore 560 064, India
| | - Ujjwal Rathore
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India
| | - Anjali Verma
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P. O., Bangalore 560 064, India
| | - Ranga Udaykumar
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P. O., Bangalore 560 064, India
| | - Raghavan Varadarajan
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India; Chemical Biology Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P. O., Bangalore 560 064, India.
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18
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Martínez-Avila O, Hijazi K, Marradi M, Clavel C, Campion C, Kelly C, Penadés S. Gold manno-glyconanoparticles: multivalent systems to block HIV-1 gp120 binding to the lectin DC-SIGN. Chemistry 2010; 15:9874-88. [PMID: 19681073 DOI: 10.1002/chem.200900923] [Citation(s) in RCA: 153] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The HIV envelope glycoprotein gp120 takes advantage of the high-mannose clusters on its surface to target the C-type lectin dendritic cell-specific intracellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) on dendritic cells. Mimicking the cluster presentation of oligomannosides on the virus surface is a strategy for designing carbohydrate-based antiviral agents. Bio-inspired by the cluster presentation of gp120, we have designed and prepared a small library of multivalent water-soluble gold glyconanoparticles (manno-GNPs) presenting truncated (oligo)mannosides of the high-mannose undecasaccharide Man(9)GlcNAc(2) and have tested them as inhibitors of DC-SIGN binding to gp120. These glyconanoparticles are ligands for DC-SIGN, which also interacts in the early steps of infection with a large number of pathogens through specific recognition of associated glycans. (Oligo)mannosides endowed with different spacers ending in thiol groups, which enable attachment of the glycoconjugates to the gold surface, have been prepared. manno-GNPs with different spacers and variable density of mannose (oligo)saccharides have been obtained and characterized. Surface plasmon resonance (SPR) experiments with selected manno-GNPs have been performed to study their inhibition potency towards DC-SIGN binding to gp120. The tested manno-GNPs completely inhibit the binding from the micro- to the nanomolar range, while the corresponding monovalent mannosides require millimolar concentrations. manno-GNPs containing the disaccharide Manalpha1-2Manalpha are the best inhibitors, showing more than 20 000-fold increased activity (100 % inhibition at 115 nM) compared to the corresponding monomeric disaccharide (100 % inhibition at 2.2 mM). Furthermore, increasing the density of dimannoside on the gold platform from 50 to 100 % does not improve the level of inhibition.
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Affiliation(s)
- Olga Martínez-Avila
- Laboratory of GlycoNanotechnology, Biofunctional Nanomaterial Unit, CIC biomaGUNE and CIBER-BBN, Parque Tecnológico, San Sebastián, Spain
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19
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Go EP, Chang Q, Liao HX, Sutherland LL, Alam SM, Haynes BF, Desaire H. Glycosylation site-specific analysis of clade C HIV-1 envelope proteins. J Proteome Res 2009; 8:4231-42. [PMID: 19610667 DOI: 10.1021/pr9002728] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The extensive glycosylation of HIV-1 envelope proteins (Envs), gp120/gp41, is known to play an important role in evasion of host immune response by masking key neutralization epitopes and presenting the Env glycosylation as "self" to the host immune system. The Env glycosylation is mostly conserved but continues to evolve to modulate viral infectivity. Thus, profiling Env glycosylation and distinguishing interclade and intraclade glycosylation variations are necessary components in unraveling the effects of glycosylation on Env's immunogenicity. Here, we describe a mass spectrometry-based approach to characterize the glycosylation profiles of two rVV-expressed clade C Envs by identifying the glycan motifs on each glycosylation site and determining the degree of glycosylation site occupancy. One Env is a wild-type Env, while the other is a synthetic "consensus" Env (C.CON). The observed differences in the glycosylation profiles between the two clade C Envs show that C.CON has more unutilized sites and high levels of high mannose glycans; these features mimic the glycosylation profile of a Group M consensus immunogen, CON-S. Our results also reveal a clade-specific glycosylation pattern. Discerning interclade and intraclade glycosylation variations could provide valuable information in understanding the molecular differences among the different HIV-1 clades and in designing new Env-based immunogens.
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Affiliation(s)
- Eden P Go
- Department of Chemistry, University of Kansas, Lawrence, KS 66045, USA
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20
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Reconstitution of the ancestral glycoprotein of human endogenous retrovirus k and modulation of its functional activity by truncation of the cytoplasmic domain. J Virol 2009; 83:12790-800. [PMID: 19812154 DOI: 10.1128/jvi.01368-09] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Endogenous retroviruses present in the human genome provide a rich record of ancient infections. All presently recognized elements, including the youngest and most intact proviruses of the human endogenous retrovirus K(HML-2) [HERV-K(HML-2)] family, have suffered postinsertional mutations during their time of chromosomal residence, and genes encoding the envelope glycoprotein (Env) have not been spared these mutations. In this study, we have, for the first time, reconstituted an authentic Env of a HERV-K(HML-2) provirus by back mutation of putative postinsertional amino acid changes of the protein encoded by HERV-K113. Aided by codon-optimized expression, we demonstrate that the reconstituted Env regained its ability to be incorporated into retroviral particles and to mediate entry. The original ancient HERV-K113 Env was synthesized as a moderately glycosylated gp95 precursor protein cleaved into surface and transmembrane (TM) subunits. Of the nine N-linked oligosaccharides, four are part of the TM subunit, contributing 15 kDa to its apparent molecular mass of 41 kDa. The carbohydrates, as well as the cytoplasmic tail, are critical for efficient intracellular trafficking, processing, stability, and particle incorporation. Whereas deletions of the carboxy-terminal 6 residues completely abrogated cleavage and virion association, more extensive truncations slightly enhanced incorporation but dramatically increased the ability to mediate entry of pseudotyped lentiviruses. Although the first HERV-K(HML-2) elements infected human ancestors about 30 million years ago, our findings indicate that their glycoproteins are in most respects remarkably similar to those of classical contemporary retroviruses and can still mediate efficient entry into mammalian cells.
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21
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Go EP, Irungu J, Zhang Y, Dalpathado DS, Liao HX, Sutherland LL, Alam SM, Haynes BF, Desaire H. Glycosylation site-specific analysis of HIV envelope proteins (JR-FL and CON-S) reveals major differences in glycosylation site occupancy, glycoform profiles, and antigenic epitopes' accessibility. J Proteome Res 2008; 7:1660-74. [PMID: 18330979 DOI: 10.1021/pr7006957] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The HIV-1 envelope (Env) is a key determinant in mediating viral entry and fusion to host cells and is a major target for HIV vaccine development. While Env is typically about 50% glycan by mass, glycosylation sites are known to evolve, with some glycosylation profiles presumably being more effective at facilitating neutralization escape than others. Thus, characterizing glycosylation patterns of Env and native virions and correlating glycosylation profiles with infectivity and Env immunogenicity are necessary first steps in designing effective immunogens. Herein, we describe a mass spectrometry-based strategy to determine HIV-1 Env glycosylation patterns and have compared two mammalian cell expressed recombinant Env immunogens, one a limited immunogen and one that induces cross-clade neutralizing antibodies. We have used a glycopeptide-based mass mapping approach to identify and characterize Env's glycosylation patterns by elucidating which sites are utilized and what type of glycan motif is present at each glycosylation site. Our results show that the immunogens displayed different degrees of glycosylation as well as a different characteristic set of glycan motifs. Thus, these techniques can be used to (1) define glycosylation profiles of recombinant Env proteins and Env on mature virions, (2) define specific carbohydrate moieties at each glycosylation site, and (3) determine the role of certain carbohydrates in HIV-1 infectivity and in modulation of Env immunogenicity.
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Affiliation(s)
- Eden P Go
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, USA
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22
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Fenouillet E, Barbouche R, Jones IM. Cell entry by enveloped viruses: redox considerations for HIV and SARS-coronavirus. Antioxid Redox Signal 2007; 9:1009-34. [PMID: 17567241 DOI: 10.1089/ars.2007.1639] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
For enveloped viruses, genome entry into the target cell involves two major steps: virion binding to the cell-surface receptor and fusion of the virion and cell membranes. Virus-cell membrane fusion is mediated by the virus envelope complex, and its fusogenicity is the result of an active virus-cell interaction process that induces conformation changes within the envelope. For some viruses, such as influenza, exposure to an acidic milieu within the cell during the early steps of infection triggers the necessary structural changes. However, for other pathogens which are not exposed to such environmental stress, activation of fusogenicity can result from precise thiol/disulfide rearrangements mediated by either an endogenous redox autocatalytic isomerase or a cell-associated oxidoreductase. Study of the activation of HIV envelope fusogenicity has revealed new knowledge about how redox changes within a viral envelope trigger fusion. We discuss these findings and their implication for anti-HIV therapy. In addition, to compare and contrast the situation outlined for HIV with an enveloped virus that can fuse with the cell plasma membrane independent of the redox status of its envelope protein, we review parallel data obtained on SARS coronavirus entry.
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Affiliation(s)
- Emmanuel Fenouillet
- CNRS FRE2738 and Université de la Méditerranée, Faculté de Médecine, Marseille, France.
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23
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Abstract
The glycoprotein (gp) 120 subunit is an important part of the envelope spikes that decorate the surface of HIV-1 and a major target for neutralizing antibodies. However, immunization with recombinant gp120 does not elicit neutralizing antibodies against multiple HIV-1 isolates (broadly neutralizing antibodies), and gp120 failed to demonstrate vaccine efficacy in recent clinical trials. Ongoing crystallographic studies of gp120 molecules from HIV-1 and SIV increasingly reveal how conserved regions, which are the targets of broadly neutralizing antibodies, are concealed from immune recognition. Based on this structural insight and that from studies of antibody structures, a number of strategies are being pursued to design immunogens that can elicit broadly neutralizing antibodies to gp120. These include (a) the construction of mimics of the viral envelope spike and (b) the design of antigens specifically tailored to induce broadly neutralizing antibodies.
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Affiliation(s)
- Ralph Pantophlet
- Department of Immunology, The Scripps Research Institute, La Jolla, California 92037, USA.
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24
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van Anken E, Braakman I. Versatility of the endoplasmic reticulum protein folding factory. Crit Rev Biochem Mol Biol 2005; 40:191-228. [PMID: 16126486 DOI: 10.1080/10409230591008161] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The endoplasmic reticulum (ER) is dedicated to import, folding and assembly of all proteins that travel along or reside in the secretory pathway of eukaryotic cells. Folding in the ER is special. For instance, newly synthesized proteins are N-glycosylated and by default form disulfide bonds in the ER, but not elsewhere in the cell. In this review, we discuss which features distinguish the ER as an efficient folding factory, how the ER monitors its output and how it disposes of folding failures.
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Affiliation(s)
- Eelco van Anken
- Department of Cellular Protein Chemistry, Bijvoet Center, Utrecht University, The Netherlands
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25
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Pikora C, Wittish C, Desrosiers RC. Identification of two N-linked glycosylation sites within the core of the simian immunodeficiency virus glycoprotein whose removal enhances sensitivity to soluble CD4. J Virol 2005; 79:12575-83. [PMID: 16160185 PMCID: PMC1211561 DOI: 10.1128/jvi.79.19.12575-12583.2005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Using PCR mutagenesis to disrupt the NXT/S N-linked glycosylation motif of the Env protein, we created 27 mutants lacking 1 to 5 of 14 N-linked glycosylation sites within regions of gp120 lying outside of variable loops 1 to 4 within simian immunodeficiency virus strain 239 (SIV239). Of 18 mutants missing N-linked glycosylation sites predicted to lie within 10 A of CD4 contact sites, the infectivity of 12 was sufficient to measure sensitivity to neutralization by soluble CD4 (sCD4), pooled immune sera from SIV239-infected rhesus macaques, and monoclonal antibodies known to neutralize certain derivatives of SIV239. Three of these 12 mutants (g3, lacking the 3rd glycan at position 79; g11, lacking the 11th glycan at position 212; and g3,11, lacking both the 3rd and 11th glycans) were approximately five times more sensitive to neutralization by sCD4 than wild-type (WT) SIV239. However, these same mutants were no more sensitive to neutralization than WT by pooled immune sera. The other 9 of 12 replication-competent mutants in this group were no more sensitive to neutralization than the WT by any of the neutralizing reagents. Six of the nine mutants that did not replicate appreciably had three or more glycosylation sites eliminated; the other three replication-deficient strains involved mutation of site 15. Our results suggest that elimination of glycan attachment sites 3 and 11 enhanced the exposure of contact residues for CD4. Thus, glycans at positions 3 and 11 of SIV239 gp120 may be particularly important for shielding the CD4-binding site from antibody recognition.
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Affiliation(s)
- Cheryl Pikora
- New England Primate Research Center, Harvard Medical School, One Pine Hill Drive, Southborough, MA 01722, USA
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26
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Lüftenegger D, Picard-Maureau M, Stanke N, Rethwilm A, Lindemann D. Analysis and function of prototype foamy virus envelope N glycosylation. J Virol 2005; 79:7664-72. [PMID: 15919919 PMCID: PMC1143653 DOI: 10.1128/jvi.79.12.7664-7672.2005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The prototype foamy virus (PFV) glycoprotein, which is essential for PFV particle release, displays a highly unusual biosynthesis, resulting in posttranslational cleavage of the precursor protein into three particle-associated subunits, i.e., leader peptide (LP), surface (SU), and transmembrane (TM). Glycosidase digestion of metabolically labeled PFV particles revealed the presence of N-linked carbohydrates on all subunits. The differential sensitivity to specific glycosidases indicated that all oligosaccharides on LP and TM are of the high-mannose or hybrid type, whereas most of those attached to SU, which contribute to about 50% of its molecular weight, are of the complex type. Individual inactivation of all 15 potential N-glycosylation sites in PFV Env demonstrated that 14 are used, i.e., 1 out of 2 in LP, 10 in SU, and 3 in TM. Analysis of the individual altered glycoproteins revealed defects in intracellular processing, support of particle release, and infectivity for three mutants, having the evolutionarily conserved glycosylation sites N8 in SU or N13 and N15 in the cysteine-rich central "sheets-and-loops" region of TM inactivated. Examination of alternative mutants with mutations affecting glycosylation or surrounding sequences at these sites indicated that inhibition of glycosylation at N8 and N13 most likely is responsible for the observed replication defects, whereas for N15 surrounding sequences seem to contribute to a temperature-sensitive phenotype. Taken together these data demonstrate that PFV Env and in particular the SU subunit are heavily N glycosylated and suggest that although most carbohydrates are dispensable individually, some evolutionarily conserved sites are important for normal Env function of FV isolates from different species.
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Affiliation(s)
- Daniel Lüftenegger
- Institut für Virologie, Medizinische Fakultät "Carl Gustav Carus," Technische Universität Dresden, Fetscherstr. 74, 01307 Dresden, Germany
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Reynard F, Fatmi A, Verrier B, Bedin F. HIV-1 acute infection env glycomutants designed from 3D model: effects on processing, antigenicity, and neutralization sensitivity. Virology 2004; 324:90-102. [PMID: 15183057 DOI: 10.1016/j.virol.2004.03.022] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2004] [Revised: 03/05/2004] [Accepted: 03/22/2004] [Indexed: 11/30/2022]
Abstract
The human immunodeficiency virus type 1 (HIV-1) envelope protein (Env) has evolved to limit its overall immunogenicity by extensive glycosylation. Only a few studies dealing with glycosylation sites have taken into account available 3D data in a global approach. We compared primary env sequences from patients with acute HIV-1 infection. Conserved N-glycosylation sites were placed on the gp120-3D model. Based on vicinity, we defined glycosylation clusters. According to these clusters, we engineered plasmids encoding deglycosylated gp160 mutants. We also constructed mutants corresponding to nonclustered glycans or to the full deglycosylation of the V1 or V2 loop. After in vitro expression, mutants were tested for functionality. We also compared the inhibition of pseudotyped particles infection by human-neutralizing sera. Generally, clustered and nonclustered mutants were affected similarly. Silencing of more than one glycan had deleterious effects, independently of the type of sugar removed. However, some mutants were moderately affected by glycans removal suggesting a distinct role for these N-glycans. Additionally, compared to the wild-type pseudovirus, two of these mutants were neutralized at higher sera dilutions strengthening the importance of the location of specific N-glycans in limiting the neutralizing response. These results could guide the selection of env mutants with the fewest antigenic and functional alterations but with enhanced neutralization sensitivity.
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Affiliation(s)
- Frédéric Reynard
- FRE 2736 CNRS-bioMérieux, IFR128 Biosciences, CERVI, Lyon, France
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Barbouche R, Miquelis R, Jones IM, Fenouillet E. Protein-disulfide isomerase-mediated reduction of two disulfide bonds of HIV envelope glycoprotein 120 occurs post-CXCR4 binding and is required for fusion. J Biol Chem 2003; 278:3131-6. [PMID: 12218052 DOI: 10.1074/jbc.m205467200] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The human immunodeficiency virus (HIV) envelope (Env) glycoprotein (gp) 120 is a highly disulfide-bonded molecule that attaches HIV to the lymphocyte surface receptors CD4 and CXCR4. Conformation changes within gp120 result from binding and trigger HIV/cell fusion. Inhibition of lymphocyte surface-associated protein-disulfide isomerase (PDI) blocks HIV/cell fusion, suggesting that redox changes within Env are required. Using a sensitive assay based on a thiol reagent, we show that (i) the thiol content of gp120, either secreted by mammalian cells or bound to a lymphocyte surface enabling CD4 but not CXCR4 binding, was 0.5-1 pmol SH/pmol gp120 (SH/gp120), whereas that of gp120 after its interaction with a surface enabling both CD4 and CXCR4 binding was raised to 4 SH/gp120; (ii) PDI inhibitors prevented this change; and (iii) gp120 displaying 2 SH/gp120 exhibited CD4 but not CXCR4 binding capacity. In addition, PDI inhibition did not impair gp120 binding to receptors. We conclude that on average two of the nine disulfides of gp120 are reduced during interaction with the lymphocyte surface after CXCR4 binding prior to fusion and that cell surface PDI catalyzes this process. Disulfide bond restructuring within Env may constitute the molecular basis of the post-receptor binding conformational changes that induce fusion competence.
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Affiliation(s)
- Rym Barbouche
- CNRS, Faculté de Médecine Nord, Boulevard Pierre Dramard, Marseille, 13015 France
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29
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Hart ML, Saifuddin M, Uemura K, Bremer EG, Hooker B, Kawasaki T, Spear GT. High mannose glycans and sialic acid on gp120 regulate binding of mannose-binding lectin (MBL) to HIV type 1. AIDS Res Hum Retroviruses 2002; 18:1311-7. [PMID: 12487819 DOI: 10.1089/088922202320886352] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mannose-binding lectin (MBL) is a C-type lectin of the innate immune system that binds to carbohydrates on the surface of certain microorganisms. Previous studies showed that MBL binds to gp120, the envelope glycoprotein of HIV-1. gp120 is extensively glycosylated, with N-linked complex and high mannose carbohydrates accounting for about half of the molecular weight. The objectives of this study were to determine the types of glycans on gp120 important for MBL binding and to determine if alteration of complex glycans with neuraminidase (NA) could enhance the interaction of MBL with virus. Lectin blot analyses revealed that MBL interacted with recombinant gp120 (rgp120) from both T cell-tropic and M-tropic virus strains. Treatment of rgp120 with endoglycosidase H (eH) or endoglycosidase F1 (eF1) abrogated binding of MBL, but did not decrease binding of wheat germ agglutinin indicating that high mannose and/or hybrid N-linked glycans were required for MBL binding. Removal of sialic acids from rgp120 with NA enhanced MBL binding. Treatment of intact virus from T cell lines or primary isolates with eF1 also significantly decreased HIV binding to MBL, while treatment with NA substantially increased binding. Treatment of virus with both eF1 and NA did not decrease binding compared to NA alone suggesting that NA treatment exposed binding sites on gp120 that are not high mannose glycans. These studies provide evidence that MBL binds to HIV via high mannose carbohydrates on gp120 and shows that the interaction of MBL with virus is regulated by sialylation.
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Affiliation(s)
- Melanie L Hart
- Rush-Presbyterian-St. Luke's Medical Center, Department of Immunology/Microbiology, Chicago, Illinois 60612, USA
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Farr SA, Banks WA, Uezu K, Freed EO, Kumar VB, Morley JE. Mechanisms of HIV type 1-induced cognitive impairment: evidence for hippocampal cholinergic involvement with overstimulation of the VIPergic system by the viral coat protein core. AIDS Res Hum Retroviruses 2002; 18:1189-95. [PMID: 12487825 DOI: 10.1089/08892220260387931] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
HIV-1 is associated with a neuroAIDS syndrome that includes cognitive impairment. Several components of HIV-1 are capable of affecting cognition, but which of these is the major mediator is unknown. We injected into the lateral cerebral ventricle of mice HIV-1 pseudoviruses expressing the full viral genome with or without the viral coat glycoproteins, gp120/gp41. Only virus possessing gp120/gp41 induced defects in memory as assessed in an active avoidance T-maze footshock paradigm. By itself, gp120 also induced impairments that were reversed by hippocampal cholinergic stimulation. Paradoxically, low doses of gp120 could improve memory. Such low-dose, paradoxic improvement is a characteristic of substances that impair memory by overstimulating pathways that normally sustain memory. Consistent with this, a low, but not a high, dose of gp120 reversed memory impairment induced by overstimulation of the VIPergic system, a memory-sustaining pathway. Further characterization showed that two strains of gp120 (SF and MN) were equally effective at improving memory and that, unlike other actions of gp120, glycation was not required. We conclude that (1) the predominant cognitive-impairing component of HIV-1 is its viral coat glycoproteins, (2) gp120 impairs memory by overstimulating pathways that normally sustain memory, (3) the cognitive effect of gp120 is mediated by its protein core, and (4) gp120 likely impairs memory by affecting the cholinergic/VIPergic system.
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Affiliation(s)
- Susan A Farr
- Geriatric Research Education and Clinical Center (GRECC), VA Medical Center, St. Louis, Missouri 63106, USA
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31
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Atemezem A, Mbemba E, Marfaing R, Vaysse J, Pontet M, Saffar L, Charnaux N, Gattegno L. Human alpha-fetoprotein binds to primary macrophages. Biochem Biophys Res Commun 2002; 296:507-14. [PMID: 12176010 DOI: 10.1016/s0006-291x(02)00909-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have previously reported that alpha-fetoprotein (AFP) inhibits infection of human monocyte-derived macrophages (MDM) by R5-HIV-1 strains and that a peptide mimicking the clade B HIV-1 gp120 consensus V3 domain (V3Cs) binds to CCR5. We demonstrate here that AFP binds high- and low-affinity binding sites of MDM, characterized, respectively, by 5.15 and 100nM K(d) values. Heat denaturation or neuraminidase treatment of AFP inhibits this binding, suggesting the involvement of protein-protein and lectin-carbohydrate interactions. Moreover, AFP displaces V3Cs binding to MDM. In addition, MIP-1beta, the most specific CCR5 ligand, displaces AFP binding to MDM (IC(50)=4.3nM). Finally, we demonstrate that AFP binds to a ligand of HIV-gp120 V3Cs domain, CCR5, expressed by MDM and by HeLa cells expressing CCR5. Such binding is not observed in the presence of HeLa cells lacking CCR5. The present results provide strong evidence that AFP directly binds to CCR5 expressed by human primary macrophages and by transfected CCR5+ HeLa cells.
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Affiliation(s)
- Aurélie Atemezem
- UPRES 3410, Biothérapies, Bénéfices et Risques, UFR-SMBH, Université Paris XIII, Bobigny et Hôpital Jean Verdier, Bondy 93017, France
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32
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Lopez S, Codina C, Bastida J, Viladomat F, Davidson E, Stewart D. Biodiversity of mannose-specific lectins within Narcissus species. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2002; 50:2507-2513. [PMID: 11958613 DOI: 10.1021/jf011459v] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Mannose-specific lectins (MSLs) were isolated from the bulbs of 27 species of wild Spanish Narcissi and compared to the commercially available MSL from daffodil (Narcissus pseudonarcissus, NPA). Molecular weight analysis showed the monomers of all the MSLs were at, or around, 12.5 kD. Haemagglutination assays showed that the MSLs exhibited activities at up to four times greater than that displayed by NPA and other MSLs derived from other species such as Galanthus nivalus (snowdrop) and Allium ursinum (ramson). Elution profiles from ion exchange chromatography exhibited similarities for species within the same taxonomic section suggesting that this method could aid in species classification. Further analysis by isoelectric focusing showed many isolectins are present in vivo and that even within a single peak from ion exchange chromatography there are numerous isolectins present. The basis of the isolectin heterogeneity is suggested to reside in the tetraploidy (sometime triploidy) nature of Narcissus genes.
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Affiliation(s)
- Susanna Lopez
- Department of Natural Products, Plant Biology and Edaphology, Faculty of Pharmacy, University of Barcelona, Avenida Diagonal 643, 08028 Barcelona, Catalonia, Spain
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Papandréou MJ, Barbouche R, Guieu R, Kieny MP, Fenouillet E. The alpha-glucosidase inhibitor 1-deoxynojirimycin blocks human immunodeficiency virus envelope glycoprotein-mediated membrane fusion at the CXCR4 binding step. Mol Pharmacol 2002; 61:186-93. [PMID: 11752220 DOI: 10.1124/mol.61.1.186] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
1-Deoxynojirimycin (DNM) is a saccharide decoy that inhibits cellular alpha-glucosidase I-II activity. Treatment by DNM of human immunodeficiency virus (HIV)-infected lymphocyte cultures inhibits virus spread. The functional properties of the membrane-associated Env glycoprotein (Env) modified in the presence of DNM remain unclear because previous reports on this subject have essentially used recombinant soluble Envs whose properties differ notably from those of Env anchored on the surface of the virus. To model virus-associated Env synthesized in the presence of DNM, native Env was expressed at the surface of mammalian cells treated with DNM. As expected, its glycosylation pattern was altered in the presence of the inhibitor. Env was found able to bind CD4, whereas its ability to induce membrane fusion was abolished. The immunoreactivity of regions involved in interactions of Env with CXCR4 (V1, V2, C2, and V3) was modified and Env displayed altered interaction with this coreceptor. These results are consistent with the inhibition by DNM of virus entry at the Env/coreceptor interaction step. Finally, preliminary data indicate that suboptimal concentrations of DNM and natural or synthetic CXCR4 ligands used in combination potently inhibit the Env-mediated membrane fusion process. Altogether, our results suggest that DNM and its analogs deserve further investigation as anti-HIV agents in combination with experimental compounds targeting CXCR4 to inhibit each partner of this crucial step of HIV entry.
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34
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Atemezem A, Mbemba E, Vassy R, Slimani H, Saffar L, Gattegno L. Human alpha1-acid glycoprotein binds to CCR5 expressed on the plasma membrane of human primary macrophages. Biochem J 2001; 356:121-8. [PMID: 11336643 PMCID: PMC1221819 DOI: 10.1042/0264-6021:3560121] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We have reported previously that human alpha(1)-acid glycoprotein (AGP) inhibits the infection of human monocyte-derived macrophages (MDM) by R5 HIV-1, and that a disulphide-bridged peptide mimicking the clade B HIV-1 gp120 consensus V3 domain (V3Cs) binds specifically to CCR5 (the major co-receptor of R5 HIV strains) on these cells [Seddiki, Rabehi, Benjouad, Saffar, Ferriere, Gluckman and Gattegno (1997) Glycobiology 7, 1229-1236]. The present study demonstrates that AGP binds specifically to MDM at high- and low-affinity binding sites with K(d) values of 16 nM and 4.9 microM respectively. The fact that heat denaturation of AGP only partly inhibited this binding (43%) suggests that protein-protein interactions are involved, as well as AGP glycans which are resistant to heat denaturation. Mannan, but not dextran, is a significant inhibitor (52%) of this binding, and sequential exoglycosidase treatment of AGP, which exposes penultimate mannose residues, has a strong stimulatory effect ( approximately 2.8-fold). Therefore AGP glycans (probably mannose residues) are involved, at least partly, in the binding of AGP to MDM. In addition, AGP inhibits the binding of V3Cs and macrophage inflammatory protein-1beta (MIP-1beta) to MDM. The anti-CCR5 monoclonal antibody 2D7, specific for the second extracellular loop of CCR5, also inhibited AGP binding (67%), whereas anti-CCR5 antibodies specific for the C-terminus of CCR5 region had no effect. Native AGP, like V3Cs (but not heat-denatured AGP), binds to 46 and 33-36 kDa electroblotted AGP-bound MDM membrane ligands, characterized as CCR5 by their interactions with anti-CCR5 antibodies and with MIP-1beta. Therefore both AGP glycans and MDM CCR5 are involved in the binding of AGP to MDM. This suggests that the inhibitory effect of AGP on the infection of human primary macrophages by R5 HIV-1 may be related to specific binding of AGP to a macrophage membrane lectin or lectin-like component and to CCR5.
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Affiliation(s)
- A Atemezem
- Laboratoire de Biologie Cellulaire, JE 2138, Faculté de Médecine Léonard de Vinci, Université Paris XIII, Bobigny 93017, France
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35
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Cho MW. Assessment of HIV vaccine development: past, present, and future. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2001; 49:263-314. [PMID: 11013767 DOI: 10.1016/s1054-3589(00)49030-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Affiliation(s)
- M W Cho
- AIDS Vaccine Research and Development Unit, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
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36
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Astoul CH, Peumans WJ, Van Damme EJ. Accessibility of the high-mannose glycans of glycoprotein gp120 from human immunodeficiency virus type 1 probed by in vitro interaction with mannose-binding lectins. Biochem Biophys Res Commun 2000; 274:455-60. [PMID: 10913359 DOI: 10.1006/bbrc.2000.3166] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The direct interaction of mannose-specific plant lectins with gp120 of HIV-1 was studied by surface plasmon resonance. Inhibition experiments indicated that exposed high mannose type glycans play a key role in the interaction. Most of the lectins specifically accommodate outer alpha1,2-, alpha1,3-, or alpha1,6-linked di- or trimannosides, and especially legume lectins, also interact with the trimannoside core of the complex type glycans. The unexpected affinity of some lectins towards gp120 presumably results from conformational differences in their binding sites. These results demonstrate that mannose-specific plant lectins are powerful tools to study the accessibility and elucidate the function of the gp120 glycans in the recognition and infection of the host cells by HIV-1.
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Affiliation(s)
- C H Astoul
- Institut de Pharmacologie et Biologie Structurale, UMR-CNRS 5089, 205 Route de Narbonne, Toulouse Cedex 4, 31077, France
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37
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Chan-Fook C, Jiang WR, Clarke BE, Zitzmann N, Maidens C, McKeating JA, Jones IM. Hepatitis C virus glycoprotein E2 binding to CD81: the role of E1E2 cleavage and protein glycosylation in bioactivity. Virology 2000; 273:60-6. [PMID: 10891408 DOI: 10.1006/viro.2000.0407] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The hepatitis C virus glycoproteins E1 and 2 have been expressed using recombinant baculoviruses following fusion to the carrier protein glutathione S-transferase (GST). Proteins were expressed singly and as an E1E2 polyprotein with and without an N-terminal affinity tag. Expression of the E1E2 polyprotein, even when preceded by GST, led to processing in insect cells and detection of an E1E2 complex that could be specifically purified by glutathione affinity chromatography. Baculovirus expressed E2 and a purified GST-E1E2 protein bound to the second extracellular loop of CD81 (EC2), a reported ligand for the molecule, but not to a truncated derivative of CD81 consisting of only the central domain of the loop. Purified GST-E2, however, failed to bind to CD81 suggesting a requirement for a free E2 amino terminus for biological activity. The binding to CD81 by baculovirus expressed E2 protein was comparable to that observed for E2 derived from mammalian cells when detected by a monoclonal antibody sensitive to protein conformation. Furthermore, E2 protein expressed in insect cells in the presence of N-butyldeoxynojirimycin, an inhibitor of terminal glucose residue processing, formed complexes with E1 and bound to CD81-EC2 similarly to untreated protein. Together these data suggest that although hyperglucosylation of E2 does not have a major effect on bioactivity, polyprotein processing to reveal the free amino terminus is required.
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Affiliation(s)
- C Chan-Fook
- NERC Institute of Virology and Environmental Microbiology, Mansfield Road, Oxford, OX1 3SR
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38
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Tran NT, Taverna M, Merry AH, Chevalier M, Morgant G, Valentin C, Ferrier D. A sensitive mapping strategy for monitoring the reproducibility of glycan processing in an HIV vaccine, RGP-160, expressed in a mammalian cell line. Glycoconj J 2000; 17:401-6. [PMID: 11294506 DOI: 10.1023/a:1007160115293] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The external envelope glycoprotein (gp160) of HIV-1 is a candidate for vaccines against AIDS. Most of the surface of the molecule is shielded by carbohydrate and the structures and locations of these glycans may be important in defining the immunogenicity of the viral coat. Here we report a sensitive mapping strategy for profiling and analysing the N-glycosylation of gp160, based on chemical release of glycans, fluorescent labelling and HPLC analysis. This approach has been validated in terms of establishing the reproducibility of all steps in the analytical procedure and on overall reproducibility on a run-to-run and day-to-day basis. The validated analysis technique was used to monitor the consistency of N-glycosylation of one rgp 160 vaccine candidate produced in baby hamster kidney (BHK) cell culture. It was demonstrated that the variation in the glycan profiles of 6 different lots was not statistically significant.
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Affiliation(s)
- N T Tran
- Department of Biochemistry, University of Oxford, United Kingdom
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39
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Saifuddin M, Hart ML, Gewurz H, Zhang Y, Spear GT. Interaction of mannose-binding lectin with primary isolates of human immunodeficiency virus type 1. J Gen Virol 2000; 81:949-55. [PMID: 10725420 DOI: 10.1099/0022-1317-81-4-949] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Mannose-binding lectin (MBL) is present in human serum and plays an important role in innate immunity by binding to carbohydrate on micro-organisms. Whereas the gp120/gp41 of human immunodeficiency virus type 1 (HIV-1) contains numerous N-linked glycosylation sites and many of these sites contain high-mannose glycans which could interact with MBL, the interaction between MBL and primary isolates (PI) of HIV-1 has not been studied. To determine if PI of HIV bind to MBL, a virus capture assay was developed in which virus was incubated in MBL-coated microtitre wells followed by detection of bound virus with an ELISA for p24 antigen. The X4 HIV-1(MN) T cell line-adapted strain and PI of HIV (R5 and X4) bound to MBL. Binding of virus to MBL was via the carbohydrate-recognition domain of MBL since binding did not occur in the absence of Ca(2+) and was blocked by preincubation of MBL-coated wells with soluble mannan. The interaction of virus with MBL-coated wells was also inhibited by preincubation of virus with soluble MBL, indicating that both immobilized and soluble forms of MBL bound to HIV. Although host cell glycoproteins are incorporated into the membrane of HIV, binding of virus to immobilized MBL required expression of gp120/gp41 on virus particles, suggesting the presence of either an unusually high carbohydrate density and/or a unique carbohydrate structure on gp120/gp41 that is the target of MBL. This study shows that PI of HIV bind to MBL and suggests that MBL can selectively interact with HIV in vivo via carbohydrate structures on gp120/gp41.
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Affiliation(s)
- M Saifuddin
- Department of Immunology/Microbiology, Rush University, 1653 West Congress Parkway, Chicago, IL 60612, USA.
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40
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Tran NT, Taverna M, Chevalier M, Ferrier D. One-step capillary isoelectric focusing for the separation of the recombinant human immunodeficiency virus envelope glycoprotein glycoforms. J Chromatogr A 2000; 866:121-35. [PMID: 10681015 DOI: 10.1016/s0021-9673(99)01045-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
One-step capillary isoelectric focusing was investigated as a rapid method to resolve the glycoforms of the heterogeneous recombinant human immunodeficiency virus (HIV) envelope glycoprotein (rgp 160sMN/LAI). The separation was performed in a poly(vinyl alcohol) (PVA) coated capillary using a mixture of ampholyte of narrow and wide pH range. A combination of saccaharose and 3-(cyclohexylamino)-1-propanesulfonic acid was shown to be the most efficient additive to avoid protein precipitation which occurs at a pH close to its pI. Although the calibration curve [isoelectric point (pI) vs. migration times] showed a non-linear relationship, an adequate linearity could be yielded for short pI ranges permitting to exhibit the acidic character of the different glycoforms of the rgp 160s MN/LAI (pI from 4.00 to 4.95). Reproducibility evaluated by comparing the performance of a polyacrylamide and a PVA coated capillary showed that low RSD values were obtained for intra-day (0.5 to 1.9%) and inter-day (1.6 to 7.6%) measurements using the PVA capillary. Moreover, the long term stability of the PVA capillary was demonstrated by measuring the variation of migration times of the protein markers for a long period of use. Finally, this method was able to differentiate the glycoform pattern of two close glycoproteins such as the rgp 160 of two sub-populations of the virus HIV-1.
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Affiliation(s)
- N T Tran
- Laboratoire de Chimie Analytique, Faculté de Pharmacie, Châtenay-Malabry, France
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41
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Quinkal I, Hernandez JF, Chevallier S, Arlaud GJ, Vernet T. Mapping of the interaction between the immunodominant loop of the ectodomain of HIV-1 gp41 and human complement protein C1q. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 265:656-63. [PMID: 10504397 DOI: 10.1046/j.1432-1327.1999.00757.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The human immunodeficiency virus type 1 transmembrane envelope glycoprotein gp41 has been previously shown to activate the C1 complex of human complement through direct interaction with its C1q subunit. The major interaction site has been located within the gp41 immunodominant region (residues 590-620), and a synthetic peptide overlapping residues 601-613 of gp41 (sequence GIWGCSGKLICTT) was shown to inhibit binding of gp41 to C1q in vitro (Thielens, N.M., Bally, I.M., Ebenbichler, C.F., Dierich, M.P. & Arlaud, G.J. (1993) J. Immunol. 151, 6583-6592). The ectodomain of gp41 (s-gp41) was secreted from the methylotrophic yeast Pichia pastoris and purified by immunoaffinity chromatography. Enzymatic deglycosylation of the recombinant s-gp41 was necessary to allow its in vitro interaction with C1q. A solid-phase competition assay was used to monitor the effect of mutant peptides derived from segment 601-613 of gp41 on the binding of deglycosylated s-gp41 to C1q. Whereas mutation of Ser606 had no effect, replacement of Ile602, Trp603, Lys608, Leu609 and Ile610 by Ala abolished the ability of the resulting peptides to inhibit binding of s-gp41 to C1q, suggesting that these residues participate in the interaction between gp41 and C1q. These findings are discussed in the light of a structural model of the immunodominant loop of gp41. It is proposed that the recognition of gp41 by C1q is driven by hydrophobic interactions, and that the sites of gp41 responsible for interaction with gp120 and C1q partly overlap.
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Affiliation(s)
- I Quinkal
- Laboratoire d'Ingénierie des Macromolécules, Institut de Biologie Structurale Jean-Pierre Ebel, Grenoble, France
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Abstract
The term 'receptor' is generally accepted as the cell-surface component that participates in virus binding and facilitates subsequent viral infection. Recent advances in technology have permitted the identification of several virus receptors, increasing our understanding of the significance of this initial virus-cell and virus-host interaction. Virus binding was previously considered to involve simple recognition and attachment to a single cell surface molecule by virus attachment proteins. The classical concept of these as single entities that participate in a lock-and-key-type process has been superseded by new data indicating that binding can be a multistep process, often involving different virus-attachment proteins and more than one host-cell receptor.
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Affiliation(s)
- L Jindrák
- Faculty of Biology, University of South Bohemia, Ceské Budĕjovice, Czech Republic
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Barbouche R, Fenouillet E, Papandréou MJ, Kiény MP, Sabatier JM. Properties of HIV envelope expressed in the presence of SPC3, an Env-derived peptide drug under phase II clinical trials. THE JOURNAL OF PEPTIDE RESEARCH : OFFICIAL JOURNAL OF THE AMERICAN PEPTIDE SOCIETY 1998; 52:283-8. [PMID: 9832306 DOI: 10.1111/j.1399-3011.1998.tb01242.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
A multibranched peptide construct (SPC3) derived from the conserved sequence of the third variable domain (V3) of the human immunodeficiency virus (HIV) envelope (Env) inhibits HIV infectivity. It is being tested in phase II clinical trials (FDA protocol 257A). Because some Env-derived peptides inhibit HIV infectivity through alteration of Env biosynthetic pathway, we studied whether SPC3 displays its activity through interference with Env biosynthesis or with its functions at the membrane. Syncytium formation was impaired when human CD4+ cells expressed recombinant HIV Env in the presence of SPC3. This inhibition was not due to an effect of SPC3 on the amount of Env expressed at the cell membrane. As assessed using antibodies, the conformation of the receptor binding site and of V3 presented on membrane Env was not affected by the presence of SPC3 during biosynthesis. Finally, despite the ability of SPC3 to bind to CD4+ cell membrane, SPC3 did not interfere with Env binding to CD4. These data suggest that SPC3 interferes with the infection process at a post-CD4 binding step, and not with the folding of Env.
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Affiliation(s)
- R Barbouche
- CNRS, Faculté de Médecine Nord, Marseille, France
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Perrin C, Fenouillet E, Jones IM. Role of gp41 glycosylation sites in the biological activity of human immunodeficiency virus type 1 envelope glycoprotein. Virology 1998; 242:338-45. [PMID: 9514971 DOI: 10.1006/viro.1997.9016] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The requirement for glycosylation in the transmembrane protein, gp41, of human immunodeficiency virus type 1 envelope protein for fusion activity has been studied. By using a mutant gene in which three conserved sites have been removed and which shows no fusion ability, genes were constructed which replace one, two, or three sites in all possible combinations. Following expression of the resultant proteins using the vaccinia T7 system, each Env variant was assessed by visual and quantitative syncytium assays. Our data indicate that two sites are sufficient for high levels of fusion and that the single site at position 621 is the most critical of all positions. We interpret our data in the light of previous contradictory reports on the role of gp41 glycosylation in bioactivity and the emerging structure of gp41.
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Affiliation(s)
- C Perrin
- NERC Institute of Virology, Oxford, United Kingdom
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45
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Binley JM, Wyatt R, Desjardins E, Kwong PD, Hendrickson W, Moore JP, Sodroski J. Analysis of the interaction of antibodies with a conserved enzymatically deglycosylated core of the HIV type 1 envelope glycoprotein 120. AIDS Res Hum Retroviruses 1998; 14:191-8. [PMID: 9491908 DOI: 10.1089/aid.1998.14.191] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The binding of a panel of monoclonal antibodies to V1, V2, and V3 loop-deleted HIV-1 gp120 was studied by competition analysis. Most of the previously defined relationships between gp120 epitopes were preserved on the variable loop-deleted protein, although interactions between some epitopes were dependent on the presence of the V1, V2, and V3 loops. Enzymatic deglycosylation of the variable loop-deleted protein only minimally altered the binding of most antibodies examined. Thus, a carbohydrate-deficient, conserved HIV-1 gp120 core can be produced that has a structure closely approximating that of the full-length, correctly folded gp120 monomer.
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Affiliation(s)
- J M Binley
- Aaron Diamond AIDS Research Center, The Rockefeller University, New York, New York 10016, USA
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46
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McInerney TL, El Ahmar W, Kemp BE, Poumbourios P. Mutation-directed chemical cross-linking of human immunodeficiency virus type 1 gp41 oligomers. J Virol 1998; 72:1523-33. [PMID: 9445056 PMCID: PMC124634 DOI: 10.1128/jvi.72.2.1523-1533.1998] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The human immunodeficiency virus type 1 transmembrane protein gp41 oligomer anchors the attachment protein, gp120, to the viral envelope and mediates viral envelope-cell membrane fusion following gp120-CD4 receptor-chemokine coreceptor binding. We have used mutation-directed chemical cross-linking with bis(sulfosuccinimidyl)suberate (BS3) to investigate the architecture of the gp41 oligomer. Treatment of gp41 with BS3 generates a ladder of four bands on sodium dodecyl sulfate-polyacrylamide gels, corresponding to monomers, dimers, trimers, and tetramers. By systematically replacing gp41 lysines with arginine and determining the mutant gp41 cross-linking pattern, we observed that gp41 N termini are cross-linked. Lysine 678, which is close to the transmembrane sequence, was readily cross-linked to Lys-678 on other monomers within the oligomeric structure. This arrangement appears to be facilitated by the close packing of membrane-anchoring sequences, since the efficiency of assembly of heterooligomers between wild-type and mutant Env proteins is improved more than twofold if the mutant contains the membrane-anchoring sequence. We also detected close contacts between Lys-596 and Lys-612 in the disulfide-bonded loop/glycan cluster of one monomer and lysines in the N-terminal amphipathic alpha-helical oligomerization domain (Lys-569 and Lys-583) and C-terminal alpha-helical sequence (Lys-650 and Lys-660) of adjacent monomers. Precursor-processing efficiency, gp120-gp41 association, soluble recombinant CD4-induced shedding of gp120 from cell surface gp41, and acquisition of gp41 ectodomain conformational antibody epitopes were unaffected by the substitutions. However, the syncytium-forming function was most dependent on the conserved Lys-569 in the N-terminal alpha-helix. These results indicate that gp160-derived gp41 expressed in mammalian cells is a tetramer and provide information about the juxtaposition of gp41 structural elements within the oligomer.
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Affiliation(s)
- T L McInerney
- St. Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia
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Papandreou MJ, Fenouillet E. Effect of changes in the glycosylation of the human immunodeficiency virus type 1 envelope on the immunoreactivity and sensitivity to thrombin of its third variable domain. Virology 1998; 241:163-7. [PMID: 9454727 DOI: 10.1006/viro.1997.8930] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The influence of HIV Env glycosylation on the conformation of the third variable domain (V3) of Env was studied by both deglycosylation of mature Env and the use of Env produced by recombinant systems in which alpha-glucosidase activity was inhibited by either deoxynojirimycin (DNM) or mutation. Selective deglycosylation affected anti-V3 antibody binding. The immunoreactivity and sensitivity to thrombin cleavage of V3 presented on Env produced in baby hamster kidney cells were changed by DNM treatment. In contrast, Env expressed in alpha-glucosidase I-deficient Chinese hamster ovary cells or in their parental cells treated by DNM fully retained these V3 properties. These results are discussed in relation to the inconsistent data obtained on V3 property changes resulting from Env glycosylation changes.
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48
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Ogawa S, Ashiura M, Uchida C. Synthesis of alpha-glucosidase inhibitors: kojibiose-type pseudo-disaccharides and a related pseudotrisaccharide. Carbohydr Res 1998; 307:83-95. [PMID: 9658566 DOI: 10.1016/s0008-6215(98)00045-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Two kojibiose-type pseudo-disaccharides and a trisaccharide, containing a 5-amino-1,2,3,4-cyclopentanetetrol derivative or valienamine, linked by way of nitrogen bridges to the sugar residues, have been designed and synthesized as processing alpha-glucosidase I inhibitors. Synthesis of the pseudo-disaccharides was carried out starting from the coupling products of the sugar isothiocyanates and an aminocyclitol, respectively, by cyclization with mercury(II) oxide to the cyclic isoureas and subsequent deprotection. Pseudokojibiose was prepared in a poor yield by reaction of a protected valienamine and a sugar epoxide, followed by deprotection. Although the pseudooligosaccharides are all strong inhibitors of alpha-glucosidase (baker's yeast), they did not have any inhibitory potency against either sucrase isomaltase (rat intestine) or processing alpha-glucosidase (rat liver microsomes).
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Affiliation(s)
- S Ogawa
- Department of Applied Chemistry, Faculty of Science and Technology, Keio Univeristy, Yokohama, Japan
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49
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Abstract
Neutral complex-type N-glycans of the envelope glycoprotein 120 of HIV-2, propagated in different host cells, display cell-type specific variations. In order to identify typical structural elements, glycans were analysed by gel filtration, by enzymic sequencing and, in part, by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The characteristic substituents of di- tri- and tetraantennary carbohydrate units thus observed include N-acetyllactosamine repeats, bisecting N-acetylglucosamine and fucose linked to the chitobiose core as well as to N-acetyllactosamine antennae. Each glycoprotein preparation displayed a characteristic set of glycoforms.
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Affiliation(s)
- S Liedtke
- Institute of Biochemistry, University of Giessen, Germany
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50
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Abstract
The various functions of human (HIV) and simian (SIV) immunodeficiency virus glycoproteins are similar, so it may be assumed that the overall structure of the folded proteins will be maintained. To preserve structure there must be constraints on sequence variation. The majority of mutations tolerated will be involved in immune escape but changes at some positions are known to have direct effects on glycoprotein expression and function. This allows the virus to change its phenotype and escape immune pressure. These properties will influence the fitness of the virus to infect and replicate in potential hosts. A better understanding of the structure-function relationships of HIV/SIV glycoproteins will assist in the development of vaccines and antivirals. Here, we identify similarities and differences between HIV-1 subtypes and HIV/SIV types that may be relevant to the phenotypes of the various groups. The results are discussed in relation to what is known of domain-function associations for HIV/SIV glycoproteins.
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Affiliation(s)
- N W Douglas
- Virology Division, National Institute for Medical Research, London, UK
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