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Munt JE, Henein S, Adams C, Young E, Hou YJ, Conrad H, Zhu D, Dong S, Kose N, Yount B, Meganck RM, Tse LPV, Kuan G, Balmaseda A, Ricciardi MJ, Watkins DI, Crowe JE, Harris E, DeSilva AM, Baric RS. Homotypic antibodies target novel E glycoprotein domains after natural DENV 3 infection/vaccination. Cell Host Microbe 2023; 31:1850-1865.e5. [PMID: 37909048 PMCID: PMC11221912 DOI: 10.1016/j.chom.2023.10.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 07/31/2023] [Accepted: 10/04/2023] [Indexed: 11/02/2023]
Abstract
The envelope (E) glycoprotein is the primary target of type-specific (TS) neutralizing antibodies (nAbs) after infection with any of the four distinct dengue virus serotypes (DENV1-4). nAbs can be elicited to distinct structural E domains (EDs) I, II, or III. However, the relative contribution of these domain-specific antibodies is unclear. To identify the primary DENV3 nAb targets in sera after natural infection or vaccination, chimeric DENV1 recombinant encoding DENV3 EDI, EDII, or EDIII were generated. DENV3 EDII is the principal target of TS polyclonal nAb responses and encodes two or more neutralizing epitopes. In contrast, some were individuals vaccinated with a DENV3 monovalent vaccine-elicited serum TS nAbs targeting each ED in a subject-dependent fashion, with an emphasis on EDI and EDIII. Vaccine responses were also sensitive to DENV3 genotypic variation. This DENV1/3 panel allows the measurement of serum ED TS nAbs, revealing differences in TS nAb immunity after natural infection or vaccination.
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Affiliation(s)
- Jennifer E Munt
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, USA
| | - Sandra Henein
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC, USA
| | - Cameron Adams
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC, USA
| | - Ellen Young
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, USA
| | - Yixuan J Hou
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, USA
| | - Helen Conrad
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, USA
| | - Deanna Zhu
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, USA
| | - Stephanie Dong
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, USA
| | - Nurgun Kose
- Vanderbilt Vaccine Center, Nashville, TN, USA
| | - Boyd Yount
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, USA
| | - Rita M Meganck
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, USA
| | - Long Ping V Tse
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, USA
| | - Guillermina Kuan
- Health Center Socrates Flores Vivas, Ministry of Health, Managua, Nicaragua; Sustainable Sciences Institute, Managua, Nicaragua
| | - Angel Balmaseda
- Sustainable Sciences Institute, Managua, Nicaragua; National Virology Laboratory, National Center for Diagnosis and Reference, Ministry of Health, Managua, Nicaragua
| | | | - David I Watkins
- University of Massachusetts Medical School, Worcester, MA, USA
| | | | - Eva Harris
- Division of Infectious Diseases and Vaccinology, School of Public Health, University of California Berkeley, Berkeley, CA, USA
| | - Aravinda M DeSilva
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC, USA
| | - Ralph S Baric
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, USA; Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC, USA.
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2
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T. G. S, Siddiqui SA, Dubey KD. Unraveling key interactions and the mechanism of demethylation during hAGT-mediated DNA repair via simulations. Front Mol Biosci 2022; 9:975046. [PMID: 36188219 PMCID: PMC9515978 DOI: 10.3389/fmolb.2022.975046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 08/15/2022] [Indexed: 11/13/2022] Open
Abstract
Alkylating agents pose the biggest threat to the genomic integrity of cells by damaging DNA bases through regular alkylation. Such damages are repaired by several automated types of machinery inside the cell. O6-alkylguanine-DNA alkyltransferase (AGT) is an enzyme that performs the direct repair of an alkylated guanine base by transferring the alkyl group to a cysteine residue. In the present study, using extensive MD simulations and hybrid QM/MM calculations, we have investigated the key interactions between the DNA lesion and the hAGT enzyme and elucidated the mechanisms of the demethylation of the guanine base. Our simulation shows that the DNA lesion is electrostatically stabilized by the enzyme and the Arg135 of hAGT enzyme provides the main driving force to flip the damaged base into the enzyme. The QM/MM calculations show demethylation of the damaged base as a three-step process in a thermodynamically feasible and irreversible manner. Our calculations show that the final product forms via Tyr114 in a facile way in contrast to the previously proposed Lys-mediated route.
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Affiliation(s)
- Shruti T. G.
- Department of Life Sciences, School of Natural Sciences, Shiv Nadar Institution of Eminence Delhi-NCR, Uttar Pradesh, India
| | - Shakir Ali Siddiqui
- Department of Chemistry, School of Natural Sciences, Shiv Nadar Institution of Eminence Delhi-NCR, Uttar Pradesh, India
| | - Kshatresh Dutta Dubey
- Department of Chemistry, School of Natural Sciences, Shiv Nadar Institution of Eminence Delhi-NCR, Uttar Pradesh, India
- *Correspondence: Kshatresh Dutta Dubey,
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3
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Siddiqui SA, Dubey KD. Can the local electric field be a descriptor of catalytic activity? A case study on chorismate mutase. Phys Chem Chem Phys 2021; 24:1974-1981. [PMID: 34757367 DOI: 10.1039/d1cp03978d] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The current theoretical perception of enzymatic activity is highly reliant on the determination of the activation energy of the reactions, which is often calculated using computationally demanding quantum mechanical calculations. With the ever-increasing use of bioengineering techniques that produce too many variants of the same enzyme, a fast and accurate way to study the relative efficiency of enzymes is currently in high demand. Here, we propose the local electric field (LEF) of the enzyme along the reaction axis as a descriptor for the enzymatic activity using the example of chorismate mutase in its native form and several variants (R90A, R90G, and R90K/C88S). The study shows a direct correlation between the calculated enzymatic EF and the enzymatic activity for all the complexes. MD simulations of the Michaelis complex and the transition state analog (TSA) show a stabilizing force on the TSA due to the enzymatic EF. QM/MM and QM-only DFT calculations in the presence of an external electric field (EEF) oriented along the reaction axis show that the electric field can interact with the dipole moment of the TS, thereby stabilizing it and thus lowering the activation energy.
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Affiliation(s)
- Shakir Ali Siddiqui
- Department of Chemistry, School of Natural Sciences, Shiv Nadar University, Delhi-NCR, 201314, India.
| | - Kshatresh Dutta Dubey
- Department of Chemistry, School of Natural Sciences, Shiv Nadar University, Delhi-NCR, 201314, India. .,Center for Informatics, Department of Chemistry, School of Natural Sciences, Shiv Nadar University, Delhi-NCR, 201314, India
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4
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Dey D, Poudyal S, Rehman A, Hasan SS. Structural and biochemical insights into flavivirus proteins. Virus Res 2021; 296:198343. [PMID: 33607183 DOI: 10.1016/j.virusres.2021.198343] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 02/10/2021] [Accepted: 02/11/2021] [Indexed: 01/01/2023]
Abstract
Flaviviruses are the fastest spreading arthropod-borne viruses that cause severe symptoms such as hepatitis, hemorrhagic fever, encephalitis, and congenital deformities. Nearly 40 % of the entire human population is at risk of flavivirus epidemics. Yet, effective vaccination is restricted only to a few flaviviruses such as yellow fever and Japanese encephalitis viruses, and most recently for select cases of dengue virus infections. Despite the global spread of dengue virus, and emergence of new threats such as Zika virus and a new genotype of Japanese encephalitis virus, insights into flavivirus targets for potentially broad-spectrum vaccination are limited. In this review article, we highlight biochemical and structural differences in flavivirus proteins critical for virus assembly and host interactions. A comparative sequence analysis of pH-responsive properties of viral structural proteins identifies trends in conservation of complementary acidic-basic character between interacting viral structural proteins. This is highly relevant to the understanding of pH-sensitive differences in virus assembly in organelles such as neutral ER and acidic Golgi. Surface residues in viral interfaces identified by structural approaches are shown to demonstrate partial conservation, further reinforcing virus-specificity in assembly and interactions with host proteins. A comparative analysis of epitope conservation in emerging flaviviruses identifies therapeutic antibody candidates that have potential as broad spectrum anti-virals, thus providing a path towards development of vaccines.
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Affiliation(s)
- Debajit Dey
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 N. Greene Street, Baltimore MD 21201, USA
| | - Shishir Poudyal
- Department of Biological Sciences, Purdue University, 915 W. State Street, West Lafayette IN 47907, USA
| | - Asma Rehman
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 N. Greene Street, Baltimore MD 21201, USA
| | - S Saif Hasan
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 N. Greene Street, Baltimore MD 21201, USA; University of Maryland Marlene and Stewart Greenebaum Cancer Center, University of Maryland Medical Center, 22. S. Greene St. Baltimore MD 21201, USA; Center for Biomolecular Therapeutics, University of Maryland School of Medicine, 9600 Gudelsky Drive, Rockville MD 20850, USA.
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5
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Yadav S, Pandey V, Kumar Tiwari R, Ojha RP, Dubey KD. Does Antibody Stabilize the Ligand Binding in GP120 of HIV-1 Envelope Protein? Evidence from MD Simulation. Molecules 2021; 26:E239. [PMID: 33466381 PMCID: PMC7796314 DOI: 10.3390/molecules26010239] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 12/21/2020] [Accepted: 12/21/2020] [Indexed: 11/16/2022] Open
Abstract
CD4-mimetic HIV-1 entry inhibitors are small sized molecules which imitate similar conformational flexibility, in gp120, to the CD4 receptor. However, the mechanism of the conformational flexibility instigated by these small sized inhibitors is little known. Likewise, the effect of the antibody on the function of these inhibitors is also less studied. In this study, we present a thorough inspection of the mechanism of the conformational flexibility induced by a CD4-mimetic inhibitor, NBD-557, using Molecular Dynamics Simulations and free energy calculations. Our result shows the functional importance of Asn425 in substrate induced conformational dynamics in gp120. The MD simulations of Asn425Gly mutant provide a less dynamic gp120 in the presence of NBD-557 without incapacitating the binding enthalpy of NBD-557. The MD simulations of complexes with the antibody clearly show the enhanced affinity of NBD-557 due to the presence of the antibody, which is in good agreement with experimental Isothermal Titration Calorimetry results (Biochemistry2006, 45, 10973-10980).
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Affiliation(s)
- Shalini Yadav
- Center of Informatics and Department of Chemistry, School of Natural Sciences, Shiv Nadar University, Uttar Pradesh 201314, India;
| | - Vishnudatt Pandey
- Department of Physics, Deen Dayal Upadhyay Gorakhpur University, Uttar Pradesh 273009, India; (V.P.); (R.K.T.); (R.P.O.)
| | - Rakesh Kumar Tiwari
- Department of Physics, Deen Dayal Upadhyay Gorakhpur University, Uttar Pradesh 273009, India; (V.P.); (R.K.T.); (R.P.O.)
| | - Rajendra Prasad Ojha
- Department of Physics, Deen Dayal Upadhyay Gorakhpur University, Uttar Pradesh 273009, India; (V.P.); (R.K.T.); (R.P.O.)
| | - Kshatresh Dutta Dubey
- Center of Informatics and Department of Chemistry, School of Natural Sciences, Shiv Nadar University, Uttar Pradesh 201314, India;
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6
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Huber RG, Marzinek JK, Boon PLS, Yue W, Bond PJ. Computational modelling of flavivirus dynamics: The ins and outs. Methods 2021; 185:28-38. [PMID: 32526282 PMCID: PMC7278654 DOI: 10.1016/j.ymeth.2020.06.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 04/24/2020] [Accepted: 06/04/2020] [Indexed: 02/06/2023] Open
Abstract
Enveloped viruses such as the flaviviruses represent a significant burden to human health around the world, with hundreds of millions of people each year affected by dengue alone. In an effort to improve our understanding of the molecular basis for the infective mechanisms of these viruses, extensive computational modelling approaches have been applied to elucidate their conformational dynamics. Multiscale protocols have been developed to simulate flavivirus envelopes in close accordance with biophysical data, in particular derived from cryo-electron microscopy, enabling high-resolution refinement of their structures and elucidation of the conformational changes associated with adaptation both to host environments and to immunological factors such as antibodies. Likewise, integrative modelling efforts combining data from biophysical experiments and from genome sequencing with chemical modification are providing unparalleled insights into the architecture of the previously unresolved nucleocapsid complex. Collectively, this work provides the basis for the future rational design of new antiviral therapeutics and vaccine development strategies targeting enveloped viruses.
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Affiliation(s)
- Roland G Huber
- Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street, Matrix #07-01, 138671, Singapore
| | - Jan K Marzinek
- Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street, Matrix #07-01, 138671, Singapore
| | - Priscilla L S Boon
- Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street, Matrix #07-01, 138671, Singapore; NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore (NUS), University Hall, Tan Chin Tuan Wing #04-02, 119077, Singapore; Department of Biological Sciences (DBS), National University of Singapore (NUS), 16 Science Drive 4, Building S3, Singapore
| | - Wan Yue
- Genome Institute of Singapore (GIS), Agency for Science, Technology and Research (A*STAR), 60 Biopolis Street, Genome #02-01, 138672, Singapore
| | - Peter J Bond
- Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street, Matrix #07-01, 138671, Singapore; Department of Biological Sciences (DBS), National University of Singapore (NUS), 16 Science Drive 4, Building S3, Singapore.
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7
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Zhang H, Kai ELJ, Lu L. Investigating the stability of dengue virus envelope protein dimer using well-tempered metadynamics simulations. Proteins 2019; 88:643-653. [PMID: 31697409 DOI: 10.1002/prot.25844] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 10/24/2019] [Accepted: 11/03/2019] [Indexed: 12/21/2022]
Abstract
We explored the stability of the dengue virus envelope (E) protein dimer since it is widely assumed that the E protein dimer is stabilized by drug ligands or antibodies in an acidic environment, neutralizing the virus's ability to fuse with human cells. During this process, a large conformational change of the E protein dimer is required. We performed Molecular Dynamics simulations to mimic the conformational change and stability of the dimer in neutral and acidic conditions with the well-tempered metadynamics method. Furthermore, as a few neutralizing antibodies discovered from dengue patients were reported, we used the same simulation method to examine the influence of a selected antibody on the dimer stability in both neutral and acidic conditions. We also investigated the antibody's influence on a point-mutated E protein that had been reported to interrupt the protein-antibody interaction and result in more than 95% loss of the antibody's binding ability. Our simulation results are highly consistent with the experimental conclusion that binding of the antibody to the E protein dimer neutralizes the virus, especially in a low pH condition, while the mutation of W101A or N153A significantly reduces the antibody's ability in stabilizing the E protein dimer. We demonstrate that well-tempered metadynamics can be used to accurately explore the antibody's interaction on large protein complexes such as the E protein dimer, and the computational approach in this work is promising in future antibody development.
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Affiliation(s)
- Haiping Zhang
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore.,Joint Engineering Research Center for Health Big Data Intelligent Analysis Technology, Shenzhen Institutes of Advanced Technology, Shenzhen, Guangdong Province, People's Republic of China
| | - Eric L J Kai
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Lanyuan Lu
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
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8
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Sharma KK, Marzinek JK, Tantirimudalige SN, Bond PJ, Wohland T. Single-molecule studies of flavivirus envelope dynamics: Experiment and computation. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2018; 143:38-51. [PMID: 30223001 DOI: 10.1016/j.pbiomolbio.2018.09.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 09/06/2018] [Accepted: 09/11/2018] [Indexed: 12/11/2022]
Abstract
Flaviviruses are simple enveloped viruses exhibiting complex structural and functional heterogeneities. Decades of research have provided crucial basic insights, antiviral medication and moderately successful gene therapy trials. The most infectious particle is, however, not always the most abundant one in a population, questioning the utility of classic ensemble-averaging virology approaches. Indeed, viral replication is often not particularly efficient, prone to errors or containing parallel routes. Here, we review different single-molecule sensitive fluorescence methods that are employed to investigate flaviviruses. In particular, we review how (i) time-resolved Förster resonance energy transfer (trFRET) was applied to probe dengue envelope conformations; (ii) FRET-fluorescence correlation spectroscopy to investigate dengue envelope intrinsic dynamics and (iii) single particle tracking to follow the path of dengue viruses in cells. We also discuss how such methods may be supported by molecular dynamics (MD) simulations over a range of spatio-temporal scales, to provide complementary data on the structure and dynamics of flaviviral systems. We describe recent improvements in multiscale MD approaches that allowed the simulation of dengue particle envelopes in near-atomic resolution. We hope this review is an incentive for setting up and applying similar single-molecule studies and combine them with MD simulations to investigate structural dynamics of entire flavivirus particles over the nanosecond-to-millisecond time-scale and follow viruses during infection in cells over milliseconds to minutes.
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Affiliation(s)
- Kamal Kant Sharma
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore
| | - Jan K Marzinek
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore; Bioinformatics Institute (A*STAR), 30 Biopolis Street, #07-01 Matrix, Singapore 138671, Singapore
| | - Sarala Neomi Tantirimudalige
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore
| | - Peter J Bond
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore; Bioinformatics Institute (A*STAR), 30 Biopolis Street, #07-01 Matrix, Singapore 138671, Singapore.
| | - Thorsten Wohland
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore; Department of Chemistry, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore; Centre for Bioimaging Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117557, Singapore.
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9
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New insights into flavivirus biology: the influence of pH over interactions between prM and E proteins. J Comput Aided Mol Des 2017; 31:1009-1019. [DOI: 10.1007/s10822-017-0076-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 10/09/2017] [Indexed: 10/18/2022]
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10
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Dubey KD, Tiwari G, Ojha RP. Targeting domain-III hinging of dengue envelope (DENV-2) protein by MD simulations, docking and free energy calculations. J Mol Model 2017; 23:102. [PMID: 28255859 DOI: 10.1007/s00894-017-3259-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 01/30/2017] [Indexed: 10/20/2022]
Abstract
The entry of the dengue virus is mediated by the conformational change in the envelope protein due to change in the endosomal pH. The structural study reveals that domain-III of the dengue envelope protein (DENV) shows the largest shift in its position during the entry of the virus. Therefore, targeting the hinge region of the domain-III may block the conformational changes in the DENV. In the present work, we have targeted the domain I/III hinge region using four known ligands used for the dengue envelope protein (serotype-2) and have intended to explore the specificity of one ligand R1 (5-(3-chlorophenyl)-N-(2-phenyl-2H-benzo[d][1,2,3]triazol-6-yl)furan-2-carboxamide) that succeeded the dengue inhibition by the molecular dynamics (MD) simulations in conjunction of the molecular docking and the binding free energy calculations. The residue interactions map shows Lys 296 of domain-III of the DENV-2, which might be responsible for binding small molecules between domain I/III interface, as an important residue conserved in all the dengue serotypes.
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Affiliation(s)
- Kshatresh Dutta Dubey
- Biophysics Unit, Department of Physics, Deen Dayal Upadhyay Gorakhpur University, Gorakhpur, India.
| | - Gargi Tiwari
- Biophysics Unit, Department of Physics, Deen Dayal Upadhyay Gorakhpur University, Gorakhpur, India
| | - Rajendra Prasad Ojha
- Biophysics Unit, Department of Physics, Deen Dayal Upadhyay Gorakhpur University, Gorakhpur, India
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11
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Chaudhury S, Ripoll DR, Wallqvist A. Structure-based pKa prediction provides a thermodynamic basis for the role of histidines in pH-induced conformational transitions in dengue virus. Biochem Biophys Rep 2015; 4:375-385. [PMID: 29124227 PMCID: PMC5669449 DOI: 10.1016/j.bbrep.2015.10.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 10/28/2015] [Accepted: 10/29/2015] [Indexed: 11/21/2022] Open
Abstract
pH-induced conformational changes in dengue virus (DENV) are critical to its ability to infect host cells. The envelope protein heterodimers that make up the viral envelope shift from a dimer to a trimer conformation at low-pH during membrane fusion. Previous studies have suggested that the ionization of histidine residues at low-pH is central to this pH-induced conformational change. We sought out to use molecular modeling with structure-based pKa prediction to provide a quantitative basis for the role of histidines in pH-induced conformational changes and identify which histidine residues were primarily responsible for this transition. We combined existing crystallographic and cryo-electron microscopy data to construct templates of the dimer and trimer conformations for the mature and immature virus. We then generated homology models for the four DENV serotypes and carried out structure-based pKa prediction using Rosetta. Our results showed that the pKa values of a subset of conserved histidines in DENV successfully capture the thermodynamics necessary to drive pH-induced conformational changes during fusion. Here, we identified the structural determinants underlying these pKa values and compare our findings with previous experimental results. Structure-based pKa prediction for histidines in dengue virus was carried out. Conserved histidine residues drive pH-dependent conformation changes. The mature dimer form of the envelop protein is destabilized at low-pH.
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Affiliation(s)
- Sidhartha Chaudhury
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research and Materiel Command, Ft. Detrick, MD 21702, United States
| | - Daniel R Ripoll
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research and Materiel Command, Ft. Detrick, MD 21702, United States
| | - Anders Wallqvist
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research and Materiel Command, Ft. Detrick, MD 21702, United States
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12
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Rogers DM, Kent MS, Rempe SB. Molecular basis of endosomal-membrane association for the dengue virus envelope protein. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:1041-52. [DOI: 10.1016/j.bbamem.2014.12.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 12/05/2014] [Accepted: 12/19/2014] [Indexed: 11/15/2022]
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13
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Abstract
The final stages of dengue virus fusion are thought to occur when the membrane-proximal stem drives the transmembrane anchor of the viral envelope protein (E) toward the fusion loop, buried in the target cell membrane. Crystal structures of E have lacked this essential stem region. We expressed and crystallized soluble mutant forms of the dengue virus envelope protein (sE) that include portions of the juxtamembrane stem. Their structures represent late-stage fusion intermediates. The proximal part of the stem has both intra- and intermolecular interactions, so the chain "zips up" along the trimer seam. The penultimate interaction we detected involves the conserved residue F402, which has hydrophobic contacts with a conserved surface on domain II. These interactions do not require any larger-scale changes in trimer packing. The techniques for expression and crystallization of sE containing stem reported here may allow further characterization of the final stages of flavivirus fusion.
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