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Georgoulia PS, Glykos NM. Folding Molecular Dynamics Simulation of a gp41-Derived Peptide Reconcile Divergent Structure Determinations. ACS OMEGA 2018; 3:14746-14754. [PMID: 31458149 PMCID: PMC6643504 DOI: 10.1021/acsomega.8b01579] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 10/23/2018] [Indexed: 06/10/2023]
Abstract
T-20 peptide is the first FDA-approved fusion inhibitor against AIDS/HIV-1 gp41 protein. Part of it, the gp41[659-671] peptide, that contains the complete epitope for the neutralizing 2F5 monoclonal antibody, has been found experimentally in a number of divergent structures. Herein, we attempt to reconcile them by using unbiased large-scale all-atom molecular dynamics folding simulations. We show that our approach can successfully capture the peptide's heterogeneity and reach each and every experimentally determined conformation in sub-angstrom accuracy, whilst preserving the peptide's disordered nature. Our analysis also unveils that the minor refinements within the AMBER99SB family of force fields can lead to appreciable differences in the predicted conformational stability arising from subtle differences in the helical- and β-region of the Ramachandran plot. Our work underlines the contribution of molecular dynamics simulation in structurally characterizing pharmacologically important peptides of ambiguous structure.
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Affiliation(s)
- Panagiota S Georgoulia
- Department of Molecular Biology and Genetics, Democritus University of Thrace, University Campus, Alexandroupolis 68100, Greece
| | - Nicholas M Glykos
- Department of Molecular Biology and Genetics, Democritus University of Thrace, University Campus, Alexandroupolis 68100, Greece
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2
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Tao Y, Wu Y, Zhang L. Advancements of two dimensional correlation spectroscopy in protein researches. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2018; 197:185-193. [PMID: 29409703 DOI: 10.1016/j.saa.2018.01.039] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Revised: 01/09/2018] [Accepted: 01/13/2018] [Indexed: 05/26/2023]
Abstract
The developments of two-dimensional correlation spectroscopy (2DCOS) applications in protein studies are discussed, especially for the past two decades. The powerful utilities of 2DCOS combined with various analytical techniques in protein studies are summarized. The emphasis is on the vibration spectroscopic techniques including IR, NIR, Raman and optical activity (ROA), as well as vibration circular dichroism (VCD) and fluorescence spectroscopy. In addition, some new developments, such as hetero-spectral 2DCOS, moving-window correlation, and model based correlation, are also reviewed for their utility in the investigation of the secondary structure, denaturation, folding and unfolding changes of protein. Finally, the new possibility and challenges of 2DCOS in protein research are highlighted as well.
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Affiliation(s)
- Yanchun Tao
- State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, No. 2699 Qianjin Street, Changchun 130012, China
| | - Yuqing Wu
- State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, No. 2699 Qianjin Street, Changchun 130012, China.
| | - Liping Zhang
- Department of Foundation, Jilin Business and Technology College, No. 1666 Kalunhu Street, Changchun 130507, China.
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Wu Y, Zhang L, Jung YM, Ozaki Y. Two-dimensional correlation spectroscopy in protein science, a summary for past 20years. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2018; 189:291-299. [PMID: 28823970 DOI: 10.1016/j.saa.2017.08.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 08/04/2017] [Indexed: 05/26/2023]
Abstract
Two-dimensional correlation spectroscopy (2DCOS) has been widely used to Infrared, Raman, Near IR, Optical Activity (ROA), Vibrational Circular Dichroism (VCD) and Fluorescence spectroscopy. In addition, several new developments, such as 2D hetero-correlation analysis, moving-window two-dimensional (MW2D) correlation, model based correlation (βν and kν correlation analyses) have also well incorporated into protein research. They have been used to investigate secondary structure, denaturation, folding and unfolding changes of protein, and have contributed greatly to the field of protein science. This review provides an overview of the applications of 2DCOS in the field of protein science for the past 20 year, especially to memory our old friend, Dr. Boguslawa Czarnik-Matusewicz, for her great contribution in this research field. The powerful utility of 2DCOS combined with various analytical techniques in protein studies is summarized. The noteworthy developments and perspective of 2DCOS in this field are highlighted finally.
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Affiliation(s)
- Yuqing Wu
- State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, No. 2699 Qianjin Street, Changchun 130012, China
| | - Liping Zhang
- Department of Foundation, Jilin Business and Technology College, No. 1666 Kalunhu Street, Changchun 130507, China.
| | - Young Mee Jung
- Department of Chemistry, Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon 24341, Republic of Korea
| | - Yukihiro Ozaki
- School of Science and Technology, Kwansei-Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
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4
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Ouyang Y, Yin Q, Li W, Li Z, Kong D, Wu Y, Hong K, Xing H, Shao Y, Jiang S, Ying T, Ma L. Escape from humoral immunity is associated with treatment failure in HIV-1-infected patients receiving long-term antiretroviral therapy. Sci Rep 2017; 7:6222. [PMID: 28740221 PMCID: PMC5524822 DOI: 10.1038/s41598-017-05594-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 05/31/2017] [Indexed: 01/22/2023] Open
Abstract
Interindividual heterogeneity in the disease progression of HIV-1-infected patients receiving long-term antiretroviral therapy suggests that some host-related factors may have limited treatment efficacy. To understand the nature of factors contributing to treatment failure, we performed a retrospective cohort study of 45 chronically HIV-1-infected individuals sharing a similar demographics and route of infection, compared the differences between virologically suppressed (VS) and treatment failure (TF) patients with respect to clinical, immunological and virological characteristics. We found that the baseline diversity of HIV-1 env quasispecies was the major difference between VS and TF group, and higher baseline diversity in TF patients. We further predicted TF-related env mutations using a selection pressure-based approach, followed by an analysis of these mutations based on the available three-dimensional structures of gp120/gp41 or their complexes with neutralizing antibodies. Notably, almost all of the identified residues could be mapped to the epitopes of known HIV-1 neutralizing antibodies, especially the epitopes of broadly neutralizing antibodies, and these mutations tended to compromise antibody-antigen interactions. These results indicate that the escape of HIV-1 from host humoral immunity may play a direct role in TF in long-term antiretroviral-experienced patients and that based on env gene sequence of the viruses in the patients.
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Affiliation(s)
- Yabo Ouyang
- State Key Laboratory of Infectious Disease Prevention and Control, National Center for AIDS/STD Control and Prevention (NCAIDS), Chinese Center for Disease Control and Prevention, Beijing, China and Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China.,Beijing You'an Hospital, Capital Medical University, Beijing, China and Beijing Institute of Hepatology, Beijing, China
| | - Qianqian Yin
- State Key Laboratory of Infectious Disease Prevention and Control, National Center for AIDS/STD Control and Prevention (NCAIDS), Chinese Center for Disease Control and Prevention, Beijing, China and Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China
| | - Wei Li
- Key Laboratory of Medical Molecular Virology of MOE/MOH, School of Basic Medical Sciences, Fudan University, Shanghai, China.,Protein Interactions Section, Cancer and Inflammation Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, Maryland, USA
| | - Zhenpeng Li
- State Key Laboratory of Infectious Disease Prevention and Control, National Center for AIDS/STD Control and Prevention (NCAIDS), Chinese Center for Disease Control and Prevention, Beijing, China and Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China
| | - Desheng Kong
- State Key Laboratory of Infectious Disease Prevention and Control, National Center for AIDS/STD Control and Prevention (NCAIDS), Chinese Center for Disease Control and Prevention, Beijing, China and Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China
| | - Yanling Wu
- Key Laboratory of Medical Molecular Virology of MOE/MOH, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Kunxue Hong
- State Key Laboratory of Infectious Disease Prevention and Control, National Center for AIDS/STD Control and Prevention (NCAIDS), Chinese Center for Disease Control and Prevention, Beijing, China and Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China
| | - Hui Xing
- State Key Laboratory of Infectious Disease Prevention and Control, National Center for AIDS/STD Control and Prevention (NCAIDS), Chinese Center for Disease Control and Prevention, Beijing, China and Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China
| | - Yiming Shao
- State Key Laboratory of Infectious Disease Prevention and Control, National Center for AIDS/STD Control and Prevention (NCAIDS), Chinese Center for Disease Control and Prevention, Beijing, China and Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China
| | - Shibo Jiang
- Key Laboratory of Medical Molecular Virology of MOE/MOH, School of Basic Medical Sciences, Fudan University, Shanghai, China. .,Lindsley F. Kimball Research Institute, New York Blood Center, New York, USA.
| | - Tianlei Ying
- Key Laboratory of Medical Molecular Virology of MOE/MOH, School of Basic Medical Sciences, Fudan University, Shanghai, China.
| | - Liying Ma
- State Key Laboratory of Infectious Disease Prevention and Control, National Center for AIDS/STD Control and Prevention (NCAIDS), Chinese Center for Disease Control and Prevention, Beijing, China and Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China.
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Apellániz B, Nieva JL. The Use of Liposomes to Shape Epitope Structure and Modulate Immunogenic Responses of Peptide Vaccines Against HIV MPER. PEPTIDE AND PROTEIN VACCINES 2015; 99:15-54. [DOI: 10.1016/bs.apcsb.2015.03.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Novel neutralising antibodies targeting the N-terminal helical region of the transmembrane envelope protein p15E of the porcine endogenous retrovirus (PERV). Immunol Res 2014; 58:9-19. [PMID: 23729215 DOI: 10.1007/s12026-013-8430-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Previously, immunising different species with the transmembrane envelope protein p15E of the porcine endogenous retrovirus (PERV), neutralising antibodies were induced which recognised epitopes in the fusion peptide proximal region (FPPR) and in the membrane-proximal external region (MPER). Only the MPER-specific antibodies were shown to neutralise and these antibodies targeted epitopes in the MPER similarly localised as the epitopes recognised by antibodies broadly neutralising HIV-1 such as 2F5 and 4E10. To study whether neutralising antibodies could be induced immunising with subunits of p15E, recombinant proteins corresponding to the N-terminal, the C-terminal helical region (NHR, CHR) and a p15E with a mutation in the Cys-Cys loop were produced. Whereas none of these antigens induced MPER-specific neutralising antibodies, the animals immunised with the FPPR/NHR subunit and the mutated p15E produced neutralising antibodies binding to the NHR. Therefore, for the first time, antibodies specific for the NHR and neutralising PERV were described.
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Frontiers of two-dimensional correlation spectroscopy. Part 2. Perturbation methods, fields of applications, and types of analytical probes. J Mol Struct 2014. [DOI: 10.1016/j.molstruc.2014.01.016] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Abstract
Virus-cell fusion is the primary means by which the human immunodeficiency virus-1 (HIV) delivers its genetic material into the human T-cell host. Fusion is mediated in large part by the viral glycoprotein 41 (gp41) which advances through four distinct conformational states: (i) native, (ii) pre-hairpin intermediate, (iii) fusion active (fusogenic), and (iv) post-fusion. The pre-hairpin intermediate is a particularly attractive step for therapeutic intervention given that gp41 N-terminal heptad repeat (NHR) and C-terminal heptad repeat (CHR) domains are transiently exposed prior to the formation of a six-helix bundle required for fusion. Most peptide-based inhibitors, including the FDA-approved drug T20, target the intermediate and there are significant efforts to develop small molecule alternatives. Here, we review current approaches to studying interactions of inhibitors with gp41 with an emphasis on atomic-level computer modeling methods including molecular dynamics, free energy analysis, and docking. Atomistic modeling yields a unique level of structural and energetic detail, complementary to experimental approaches, which will be important for the design of improved next generation anti-HIV drugs.
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Mühle M, Hoffmann K, Löchelt M, Denner J. Immunisation with foamy virus Bet fusion proteins as novel strategy for HIV-1 epitope delivery. Immunol Res 2013; 56:61-72. [PMID: 23440699 DOI: 10.1007/s12026-013-8387-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The induction of 2F5- and 4E10-like antibodies broadly neutralising HIV-1 and targeting the membrane external proximal region (MPER) of the transmembrane envelope protein gp41 would be a major advancement for the development of a preventive HIV-1 vaccine, but successful attempts remain rare. Recent studies demonstrated that broadly reactive antibodies develop relatively late during infection and after intensive affinity maturation. Therefore, a prolonged antigen delivery might be beneficial to induce them. Replicating foamy viruses which are characterised by apathogenic but persistent infection could represent suitable carrier viruses for this purpose. In order to develop such a system, we modified the accessory foamy virus Bet protein to contain the MPER of gp41, or the MPER linked to the stabilising fusion peptide proximal region of gp41 and analysed here the antigenic and immunogenic properties of such hybrid proteins. The antigens, expressed and purified to homogeneity, were recognised by the monoclonal antibodies 2F5 and 4E10 with nanomolar affinities and induced high levels of antibodies specific to gp41 after immunisation of rats. The antisera also bound to virus particles attached to infected cells, and peptide-based epitope mapping showed that they recognised the 2F5 epitope. Although no HIV-1 neutralising activity was observed, the presented data demonstrate that using the foamy virus Bet for HIV-1 epitope delivery is successfully applicable. Together with the attractive potential for sustained antigen expression after transfer to replicating virus, these results should therefore provide a first basis for the development of chimeric foamy viruses as novel HIV-1 vaccine vectors.
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Affiliation(s)
- Michael Mühle
- Center for HIV and Retrovirology, Robert Koch Institute, Berlin, Germany
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Mühle M, Hoffmann K, Löchelt M, Denner J. Construction and characterisation of replicating foamy viral vectors expressing HIV-1 epitopes recognised by broadly neutralising antibodies. Antiviral Res 2013; 100:314-20. [PMID: 24055836 DOI: 10.1016/j.antiviral.2013.09.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Revised: 08/26/2013] [Accepted: 09/10/2013] [Indexed: 10/26/2022]
Abstract
With the aim to develop a replicating vector system for the delivery of HIV-1 antigens on the basis of an apathogenic foamy virus we recently showed that immunisation with purified recombinant hybrid antigens composed of the feline foamy virus Bet protein and parts of the transmembrane envelope protein of HIV-1 induced antibodies with an epitope specificity identical to that of the broadly neutralising antibody 2F5 (Mühle et al., Immunol Res., 2013, 56:61-72). Here we set out to further improve the HIV-1 inserts consisting of the membrane proximal external region (MPER) and the fusion peptide proximal region (FPPR) by stepwise shortening distinct linker residues between both domains. In a subset of these antigens, enhanced recognition by 2F5 and 4E10 was observed, indicating that a specific positioning of FPPR and MPER domains is critical for improved antibody binding. Introduction of these optimised inserts as well as of the MPER domain alone into the feline foamy virus backbone was compatible with virus replication, giving viral titres similar to wild-type virus after extended passaging. Most importantly, expression of the HIV-1 transgenes in infected feline CRFK cells remained stable in three out of four constructs and was detectable after serial passages for several weeks. These data encourage further testing of these vectors in vivo, which may allow insights into the necessity of affinity maturation for the induction of broadly reactive HIV-1 antibodies.
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Affiliation(s)
- Michael Mühle
- Robert Koch Institute, Nordufer 20, 13353 Berlin, Germany
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Waechter A, Eschricht M, Denner J. Neutralization of porcine endogenous retrovirus by antibodies against the membrane-proximal external region of the transmembrane envelope protein. J Gen Virol 2013; 94:643-651. [DOI: 10.1099/vir.0.047399-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Immunization of different species including goats, rats, hamsters and guinea pigs with the recombinant ectodomain of the transmembrane envelope (TM) protein p15E of porcine endogenous retrovirus (PERV) has been shown to result in the production of virus-neutralizing antibodies. The sera recognize two groups of epitopes, one located in the fusion peptide-proximal region (FPPR) and the second in the membrane-proximal external region (MPER) of p15E. Most interestingly, the epitopes in the MPER are similar to epitopes in the TM protein gp41 of human immunodeficiency virus type 1 (HIV-1) recognized by mAbs 2F5 and 4E10, which broadly neutralize HIV-1. To study which epitope and which antibody population are involved in the process of neutralization of PERV, this study generated a new antiserum in a goat using an elongated ectodomain of p15E. The immune serum neutralized PERV at a higher titre and recognized broader epitopes in the FPPR and MPER of p15E. For the first time, antibody subpopulations were isolated from this serum using affinity chromatography with immobilized proteins and peptides corresponding to the FPPR and MPER of p15E. Only the affinity-purified antibodies specifically binding the MPER neutralized PERV, indicating that, as in the case of HIV-1, the MPER is an important target of neutralizing activity.
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Huarte N, Araujo A, Arranz R, Lorizate M, Quendler H, Kunert R, Valpuesta JM, Nieva JL. Recognition of membrane-bound fusion-peptide/MPER complexes by the HIV-1 neutralizing 2F5 antibody: implications for anti-2F5 immunogenicity. PLoS One 2012; 7:e52740. [PMID: 23285173 PMCID: PMC3528738 DOI: 10.1371/journal.pone.0052740] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Accepted: 11/21/2012] [Indexed: 11/19/2022] Open
Abstract
The membrane proximal external region (MPER) of the fusogenic HIV-1 glycoprotein-41 harbors the epitope sequence recognized by 2F5, a broadly neutralizing antibody isolated from an infected individual. Structural mimicry of the conserved MPER 2F5 epitope constitutes a pursued goal in the field of anti-HIV vaccine development. It has been proposed that 2F5 epitope folding into its native state is attained in the vicinity of the membrane interface and might involve interactions with other viral structures. Here we present results indicating that oligomeric complexes established between MPER and the conserved amino-terminal fusion peptide (FP) can partition into lipid vesicles and be specifically bound by the 2F5 antibody at their surfaces. Cryo-transmission electron microscopy of liposomes doped with MPER:FP peptide mixtures provided the structural grounds for complex recognition by antibody at lipid bilayer surfaces. Supporting the immunogenicity of the membrane-bound complex, these MPER:FP peptide-vesicle formulations could trigger cross-reactive anti-MPER antibodies in rabbits. Thus, our observations suggest that contacts with N-terminal regions of gp41 may stabilize the 2F5 epitope as a membrane-surface antigen.
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Affiliation(s)
- Nerea Huarte
- Biophysics Unit (CSIC-UPV/EHU) and Biochemistry and Molecular Biology Department, University of the Basque Country (UPV/EHU), Bilbao, Spain
| | - Aitziber Araujo
- Biophysics Unit (CSIC-UPV/EHU) and Biochemistry and Molecular Biology Department, University of the Basque Country (UPV/EHU), Bilbao, Spain
| | - Rocio Arranz
- Department of Macromolecular Structures, National Center for Biotechnology (CNB-CSIC), Madrid, Spain
| | - Maier Lorizate
- Biophysics Unit (CSIC-UPV/EHU) and Biochemistry and Molecular Biology Department, University of the Basque Country (UPV/EHU), Bilbao, Spain
| | - Heribert Quendler
- Institute of Applied Microbiology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Renate Kunert
- Institute of Applied Microbiology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - José M. Valpuesta
- Department of Macromolecular Structures, National Center for Biotechnology (CNB-CSIC), Madrid, Spain
| | - José L. Nieva
- Biophysics Unit (CSIC-UPV/EHU) and Biochemistry and Molecular Biology Department, University of the Basque Country (UPV/EHU), Bilbao, Spain
- * E-mail:
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Cerasoli E, Ravi J, Gregor C, Hussain R, Siligardi G, Martyna G, Crain J, Ryadnov MG. Membrane mediated regulation in free peptides of HIV-1 gp41: minimal modulation of the hemifusion phase. Phys Chem Chem Phys 2012; 14:1277-85. [DOI: 10.1039/c1cp23155c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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14
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Liu Y, Ke Z, Wu KY, Liu S, Chen WH, Jiang S, Jiang ZH. An Amphiphilic Conjugate Approach toward the Design and Synthesis of Betulinic Acid-Polyphenol Conjugates as Inhibitors of the HIV-1 gp41 Fusion Core Formation. ChemMedChem 2011; 6:1654-64. [DOI: 10.1002/cmdc.201100149] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2011] [Indexed: 11/07/2022]
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Ablation of the complementarity-determining region H3 apex of the anti-HIV-1 broadly neutralizing antibody 2F5 abrogates neutralizing capacity without affecting core epitope binding. J Virol 2010; 84:4136-47. [PMID: 20147404 DOI: 10.1128/jvi.02357-09] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The identification and characterization of broadly neutralizing antibodies (bnAbs) against HIV-1 has formed a major research focus, with the ultimate goal to help in the design of an effective AIDS vaccine. One of these bnAbs, 2F5, has been extensively characterized, and residues at the apex of its unusually long complementarity-determining region (CDR) H3 loop have been shown to be crucial for neutralization. Structural studies, however, have revealed that the (100)TLFGVPI(100F) apex residues of the CDR H3 loop do not interact directly with residues of its core gp41 epitope. In an attempt to gain better insight into the functional role of this element, we have recombinantly expressed native 2F5 Fab and two mutants in which either the apical Phe100B(H) residue was changed to an alanine or the CDR H3 residues (100)TLFGVPI(100F) were replaced by a Ser-Gly dipeptide linker. Isothermal titration calorimetry (ITC) and competitive-binding enzyme-linked immunosorbent assays (ELISAs) rendered strikingly similar affinity constants (K(d) [dissociation constant] of approximately 20 nM) for linear peptide epitope binding by 2F5 Fabs, independent of the presence or absence of the apex residues. Ablation of the CDR H3 apex residues, however, abolished the cell-cell fusion inhibition and pseudovirus neutralization capacities of 2F5 Fab. We report competitive ELISA data that suggest a role of 2F5 CDR H3 apex residues in mediating weak hydrophobic interactions with residues located at the C terminus of the gp41 membrane proximal external region and/or membrane components in the context of core epitope binding. The present data therefore imply an extended 2F5 paratope that includes weak secondary interactions that are crucial for neutralization of Env-mediated fusion.
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Relationship between antibody 2F5 neutralization of HIV-1 and hydrophobicity of its heavy chain third complementarity-determining region. J Virol 2009; 84:2955-62. [PMID: 20042512 DOI: 10.1128/jvi.02257-09] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The membrane-proximal external region (MPER) of the HIV-1 gp41 transmembrane glycoprotein is the target of the broadly neutralizing antibody 2F5. Prior studies have suggested a two-component mechanism for 2F5-mediated neutralization involving both structure-specific recognition of a gp41 protein epitope and nonspecific interaction with the viral lipid membrane. Here, we mutationally alter a hydrophobic patch on the third complementarity-determining region of the heavy chain (CDR H3) of the 2F5 antibody and assess the abilities of altered 2F5 variants to bind gp41 and to neutralize diverse strains of HIV-1. CDR H3 alterations had little effect on the affinity of 2F5 variants for a peptide corresponding to its gp41 epitope. In contrast, strong effects and a high degree of correlation (P < 0.0001) were found between virus neutralization and CDR H3 hydrophobicity, as defined by predicted free energies of transfer from water to a lipid bilayer interface or to octanol. The effect of CDR H3 hydrophobicity on neutralization was independent of isolate sensitivity to 2F5, and CDR H3 variants with tryptophan substitutions were able to neutralize HIV-1 approximately 10-fold more potently than unmodified 2F5. A threshold was observed for increased hydrophobicity of the 2F5 CDR H3 loop beyond which effects on 2F5-mediated neutralization leveled off. Together, the results provide a more complete understanding of the 2F5 mechanism of HIV-1 neutralization and indicate ways to enhance the potency of MPER-directed antibodies.
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