101
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Ao D, Guo HC, Sun SQ, Sun DH, Fung TS, Wei YQ, Han SC, Yao XP, Cao SZ, Liu DX, Liu XT. Viroporin Activity of the Foot-and-Mouth Disease Virus Non-Structural 2B Protein. PLoS One 2015; 10:e0125828. [PMID: 25946195 PMCID: PMC4422707 DOI: 10.1371/journal.pone.0125828] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 03/26/2015] [Indexed: 01/15/2023] Open
Abstract
Viroporins are a family of low-molecular-weight hydrophobic transmembrane proteins that are encoded by various animal viruses. Viroporins form transmembrane pores in host cells via oligomerization, thereby destroying cellular homeostasis and inducing cytopathy for virus replication and virion release. Among the Picornaviridae family of viruses, the 2B protein encoded by enteroviruses is well understood, whereas the viroporin activity of the 2B protein encoded by the foot-and-mouth disease virus (FMDV) has not yet been described. An analysis of the FMDV 2B protein domains by computer-aided programs conducted in this study revealed that this protein may contain two transmembrane regions. Further biochemical, biophysical and functional studies revealed that the protein possesses a number of features typical of a viroporin when it is overexpressed in bacterial and mammalian cells as well as in FMDV-infected cells. The protein was found to be mainly localized in the endoplasmic reticulum (ER), with both the N- and C-terminal domains stretched into the cytosol. It exhibited cytotoxicity in Escherichia coli, which attenuated 2B protein expression. The release of virions from cells infected with FMDV was inhibited by amantadine, a viroporin inhibitor. The 2B protein monomers interacted with each other to form both intracellular and extracellular oligomers. The Ca(2+) concentration in the cells increased, and the integrity of the cytoplasmic membrane was disrupted in cells that expressed the 2B protein. Moreover, the 2B protein induced intense autophagy in host cells. All of the results of this study demonstrate that the FMDV 2B protein has properties that are also found in other viroporins and may be involved in the infection mechanism of FMDV.
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Affiliation(s)
- Da Ao
- State Key Laboratory of Veterinary Etiological Biology and OIE/National Foot and Mouth Disease Reference Laboratory, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, China
- College of Veterinary Medicine, Sichuan Agricultural University, Ya’an, Sichuan, China
| | - Hui-Chen Guo
- State Key Laboratory of Veterinary Etiological Biology and OIE/National Foot and Mouth Disease Reference Laboratory, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, China
| | - Shi-Qi Sun
- State Key Laboratory of Veterinary Etiological Biology and OIE/National Foot and Mouth Disease Reference Laboratory, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, China
- * E-mail:
| | - De-Hui Sun
- State Key Laboratory of Veterinary Etiological Biology and OIE/National Foot and Mouth Disease Reference Laboratory, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, China
| | - To Sing Fung
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Yan-Quan Wei
- State Key Laboratory of Veterinary Etiological Biology and OIE/National Foot and Mouth Disease Reference Laboratory, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, China
| | - Shi-Chong Han
- State Key Laboratory of Veterinary Etiological Biology and OIE/National Foot and Mouth Disease Reference Laboratory, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, China
| | - Xue-Ping Yao
- College of Veterinary Medicine, Sichuan Agricultural University, Ya’an, Sichuan, China
| | - Sui-Zhong Cao
- College of Veterinary Medicine, Sichuan Agricultural University, Ya’an, Sichuan, China
| | - Ding Xiang Liu
- State Key Laboratory of Veterinary Etiological Biology and OIE/National Foot and Mouth Disease Reference Laboratory, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, China
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Xiang-Tao Liu
- State Key Laboratory of Veterinary Etiological Biology and OIE/National Foot and Mouth Disease Reference Laboratory, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, China
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102
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Yusibov V, Kushnir N, Streatfield SJ. Advances and challenges in the development and production of effective plant-based influenza vaccines. Expert Rev Vaccines 2014; 14:519-35. [PMID: 25487788 DOI: 10.1586/14760584.2015.989988] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Influenza infections continue to present a major threat to public health. Traditional modes of influenza vaccine manufacturing are failing to satisfy the global demand because of limited scalability and long production timelines. In contrast, subunit vaccines (SUVs) can be produced in heterologous expression systems in shorter times and at higher quantities. Plants are emerging as a promising platform for SUV production due to time efficiency, scalability, lack of harbored mammalian pathogens and possession of the machinery for eukaryotic post-translational protein modifications. So far, several organizations have utilized plant-based transient expression systems to produce SUVs against influenza, including vaccines based on virus-like particles. Plant-produced influenza SUV candidates have been extensively evaluated in animal models and some have shown safety and immunogenicity in clinical trials. Here, the authors review ongoing efforts and challenges to producing influenza SUV candidates in plants and discuss the likelihood of bringing these products to the market.
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Affiliation(s)
- Vidadi Yusibov
- Fraunhofer USA Center for Molecular Biotechnology, 9 Innovation Way, Suite 200, Newark, DE 19711, USA
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103
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Veit M, Matczuk AK, Sinhadri BC, Krause E, Thaa B. Membrane proteins of arterivirus particles: structure, topology, processing and function. Virus Res 2014; 194:16-36. [PMID: 25278143 PMCID: PMC7172906 DOI: 10.1016/j.virusres.2014.09.010] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 09/20/2014] [Accepted: 09/23/2014] [Indexed: 01/01/2023]
Abstract
Arteriviruses are important pathogens in veterinary medicine. We review the structure and processing of their membrane proteins. Some features are unique from a cell biological point of view. New data on this topic are also presented. We speculate on the role of the membrane proteins during virus entry and budding.
Arteriviruses, such as equine arteritis virus (EAV) and porcine reproductive and respiratory syndrome virus (PRRSV), are important pathogens in veterinary medicine. Despite their limited genome size, arterivirus particles contain a multitude of membrane proteins, the Gp5/M and the Gp2/3/4 complex, the small and hydrophobic E protein and the ORF5a protein. Their function during virus entry and budding is understood only incompletely. We summarize current knowledge of their primary structure, membrane topology, (co-translational) processing and intracellular targeting to membranes of the exocytic pathway, which are the budding site. We profoundly describe experimental data that led to widely believed conceptions about the function of these proteins and also report new results about processing steps for each glycoprotein. Further, we depict the location and characteristics of epitopes in the membrane proteins since the late appearance of neutralizing antibodies may lead to persistence, a characteristic hallmark of arterivirus infection. Some molecular features of the arteriviral proteins are rare or even unique from a cell biological point of view, particularly the prevention of signal peptide cleavage by co-translational glycosylation, discovered in EAV-Gp3, and the efficient use of overlapping sequons for glycosylation. This article reviews the molecular mechanisms of these cellular processes. Based on this, we present hypotheses on the structure and variability of arteriviral membrane proteins and their role during virus entry and budding.
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Affiliation(s)
- Michael Veit
- Institut für Virologie, Veterinärmedizin, Freie Universität Berlin, Germany.
| | | | | | - Eberhard Krause
- Leibniz Institute of Molecular Pharmacology (FMP), Berlin, Germany
| | - Bastian Thaa
- Institut für Virologie, Veterinärmedizin, Freie Universität Berlin, Germany
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104
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Colvin MT, Andreas LB, Chou JJ, Griffin RG. Proton association constants of His 37 in the Influenza-A M218-60 dimer-of-dimers. Biochemistry 2014; 53:5987-94. [PMID: 25184631 PMCID: PMC4179598 DOI: 10.1021/bi5005393] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
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The membrane protein M2 from influenza-A
forms a single-pass transmembrane
helix that assembles in lipid membrane as homotetramers whose primary
function is to act as a proton transporter for viral acidification.
A single residue, histidine 37 (His 37), is known to be responsible
for selectivity and plays an integral role in the protein’s
function. We report pH-dependent 15N MAS NMR spectra of
His 37 within the influenza-A proton conduction domain of M2, M218–60, which has been previously shown to be a fully
functional construct and was recently determined to adopt a dimer-of-dimers
structure in lipids. By extracting the ratio of [His]/[HisH+] as a function of pH, we obtained two doubly degenerate proton disassociation
constants, 7.63 ± 0.15 and 4.52 ± 0.15, despite a possible
maximum of four. We also report the 1HNε chemical shifts at pH 6.5 recorded at 60 kHz MAS in a CP-based 1H–15N spectrum. We were unable to detect
resonances indicative of direct proton sharing among His 37 side chains
when the tetramer is in the +2 state. In the neutral state, His 37
is exclusively in the τ tautomer, indicating that the δ
nitrogen is protonated solely as a function of pH. We also found that
the plot of [HisH+]/[His] as a function of pH is qualitatively
similar to previously reported proton conduction rates, indicating
that proton conduction rate is proportional to the level of histidine
protonation within the channel. Two-dimensional 13C–13C and 13C–15N correlations suggest
that at low pH multiple conformations are populated as the spectra
broaden and eventually disappear as the acidity is increased. A second
highly resolved state at low pH was not observed.
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Affiliation(s)
- Michael T Colvin
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
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105
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Ghosh A, Wang J, Moroz YS, Korendovych IV, Zanni M, DeGrado WF, Gai F, Hochstrasser RM. 2D IR spectroscopy reveals the role of water in the binding of channel-blocking drugs to the influenza M2 channel. J Chem Phys 2014; 140:235105. [PMID: 24952572 PMCID: PMC4098053 DOI: 10.1063/1.4881188] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 05/21/2014] [Indexed: 12/21/2022] Open
Abstract
Water is an integral part of the homotetrameric M2 proton channel of the influenza A virus, which not only assists proton conduction but could also play an important role in stabilizing channel-blocking drugs. Herein, we employ two dimensional infrared (2D IR) spectroscopy and site-specific IR probes, i.e., the amide I bands arising from isotopically labeled Ala30 and Gly34 residues, to probe how binding of either rimantadine or 7,7-spiran amine affects the water dynamics inside the M2 channel. Our results show, at neutral pH where the channel is non-conducting, that drug binding leads to a significant increase in the mobility of the channel water. A similar trend is also observed at pH 5.0 although the difference becomes smaller. Taken together, these results indicate that the channel water facilitates drug binding by increasing its entropy. Furthermore, the 2D IR spectral signatures obtained for both probes under different conditions collectively support a binding mechanism whereby amantadine-like drugs dock in the channel with their ammonium moiety pointing toward the histidine residues and interacting with a nearby water cluster, as predicted by molecular dynamics simulations. We believe these findings have important implications for designing new anti-influenza drugs.
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Affiliation(s)
- Ayanjeet Ghosh
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Jun Wang
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California 94143, USA
| | - Yurii S Moroz
- Department of Chemistry, Syracuse University, Syracuse, New York 13244, USA
| | - Ivan V Korendovych
- Department of Chemistry, Syracuse University, Syracuse, New York 13244, USA
| | - Martin Zanni
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
| | - William F DeGrado
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California 94143, USA
| | - Feng Gai
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Robin M Hochstrasser
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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106
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Perot BP, Ingersoll MA, Albert ML. The impact of macroautophagy on CD8(+) T-cell-mediated antiviral immunity. Immunol Rev 2014; 255:40-56. [PMID: 23947346 DOI: 10.1111/imr.12096] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Macroautophagy is a catabolic recycling pathway, which can be induced by various stress stimuli. Viruses are able to manipulate autophagy in the cells that they infect. The impact of autophagy on the innate immune response to viruses and its stimulatory role in antigen presentation to CD4(+) T cells are well documented. Herein, we present the impact of autophagy on the activation of cytotoxic T lymphocyte (CTL)-mediated antiviral immune responses, which are required for the eradication or control of multiple viruses. We first discuss the general mechanisms by which viruses can either induce or block autophagy in cells. We then explore the cross-talk between autophagy and innate immune processes, which are both first line defenses against viruses; and constitute crucial steps for the initiation of potent adaptive immune responses. We describe the impact of autophagy on the presentation of viral peptide antigens on class I major histocompatibility complex (MHC I), a prerequisite for the priming of CTL responses. In sum, our review highlights the interplay between viruses and three integrated host response pathways - autophagy, innate and adaptive immunity - providing a framework for future mechanistic and pathogenesis-based research.
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Affiliation(s)
- Brieuc P Perot
- Unité d'immunobiologie des cellules dendritiques, Institut Pasteur, Paris, France
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107
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OuYang B, Chou JJ. The minimalist architectures of viroporins and their therapeutic implications. BIOCHIMICA ET BIOPHYSICA ACTA 2014; 1838:1058-67. [PMID: 24055819 PMCID: PMC3943691 DOI: 10.1016/j.bbamem.2013.09.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Revised: 09/03/2013] [Accepted: 09/08/2013] [Indexed: 11/23/2022]
Abstract
Many viral genomes encode small, integral membrane proteins that form homo-oligomeric channels in membrane, and they transport protons, cations, and other molecules across the membrane barrier to aid various steps of viral entry and maturation. These viral proteins, collectively named viroporins, are crucial for viral pathogenicity. In the past five years, structures obtained by nuclear magnetic resonance (NMR), X-ray crystallography, and electron microscopy (EM) showed that viroporins often adopt minimalist architectures to achieve their functions. A number of small molecules have been identified to interfere with their channel activities and thereby inhibit viral infection, making viroporins potential drug targets for therapeutic intervention. The known architectures and inhibition mechanisms of viroporins differ significantly from each other, but some common principles are shared between them. This review article summarizes the recent developments in the structural investigation of viroporins and their inhibition by antiviral compounds. This article is part of a Special Issue entitled: Viral Membrane Proteins-Channels for Cellular Networking.
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Affiliation(s)
- Bo OuYang
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China; National Center for Protein Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China
| | - James J Chou
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China; National Center for Protein Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
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108
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Rouse SL, Marcoux J, Robinson CV, Sansom MSP. Dodecyl maltoside protects membrane proteins in vacuo. Biophys J 2014; 105:648-56. [PMID: 23931313 DOI: 10.1016/j.bpj.2013.06.025] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Revised: 05/14/2013] [Accepted: 06/17/2013] [Indexed: 11/26/2022] Open
Abstract
Molecular dynamics simulations have been used to characterize the effects of transfer from aqueous solution to a vacuum to inform our understanding of mass spectrometry of membrane-protein-detergent complexes. We compared two membrane protein architectures (an α-helical bundle versus a β-barrel) and two different detergent types (phosphocholines versus an alkyl sugar) with respect to protein stability and detergent packing. The β-barrel membrane protein remained stable as a protein-detergent complex in vacuum. Zwitterionic detergents formed conformationally destabilizing interactions with an α-helical membrane protein after detergent micelle inversion driven by dehydration in vacuum. In contrast, a nonionic alkyl sugar detergent resisted micelle inversion, maintaining the solution-phase conformation of the protein. This helps to explain the relative stability of membrane proteins in the presence of alkyl sugar detergents such as dodecyl maltoside.
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Affiliation(s)
- Sarah L Rouse
- Department of Biochemistry, University of Oxford, United Kingdom
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109
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Fan YN, Xiao X, Min JL, Chou KC. iNR-Drug: predicting the interaction of drugs with nuclear receptors in cellular networking. Int J Mol Sci 2014; 15:4915-37. [PMID: 24651462 PMCID: PMC3975431 DOI: 10.3390/ijms15034915] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Revised: 02/12/2014] [Accepted: 02/16/2014] [Indexed: 12/20/2022] Open
Abstract
Nuclear receptors (NRs) are closely associated with various major diseases such as cancer, diabetes, inflammatory disease, and osteoporosis. Therefore, NRs have become a frequent target for drug development. During the process of developing drugs against these diseases by targeting NRs, we are often facing a problem: Given a NR and chemical compound, can we identify whether they are really in interaction with each other in a cell? To address this problem, a predictor called “iNR-Drug” was developed. In the predictor, the drug compound concerned was formulated by a 256-D (dimensional) vector derived from its molecular fingerprint, and the NR by a 500-D vector formed by incorporating its sequential evolution information and physicochemical features into the general form of pseudo amino acid composition, and the prediction engine was operated by the SVM (support vector machine) algorithm. Compared with the existing prediction methods in this area, iNR-Drug not only can yield a higher success rate, but is also featured by a user-friendly web-server established at http://www.jci-bioinfo.cn/iNR-Drug/, which is particularly useful for most experimental scientists to obtain their desired data in a timely manner. It is anticipated that the iNR-Drug server may become a useful high throughput tool for both basic research and drug development, and that the current approach may be easily extended to study the interactions of drug with other targets as well.
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Affiliation(s)
- Yue-Nong Fan
- Computer Department, Jing-De-Zhen Ceramic Institute, Jingdezhen 333046, Jiangxi, China.
| | - Xuan Xiao
- Computer Department, Jing-De-Zhen Ceramic Institute, Jingdezhen 333046, Jiangxi, China.
| | - Jian-Liang Min
- Computer Department, Jing-De-Zhen Ceramic Institute, Jingdezhen 333046, Jiangxi, China.
| | - Kuo-Chen Chou
- Center of Excellence in Genomic Medicine Research (CEGMR), King Abdulaziz University, Jeddah 21589, Saudi Arabia.
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110
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He L, De Groot AS, Gutierrez AH, Martin WD, Moise L, Bailey-Kellogg C. Integrated assessment of predicted MHC binding and cross-conservation with self reveals patterns of viral camouflage. BMC Bioinformatics 2014; 15 Suppl 4:S1. [PMID: 25104221 PMCID: PMC4094998 DOI: 10.1186/1471-2105-15-s4-s1] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Background Immune recognition of foreign proteins by T cells hinges on the formation of a ternary complex sandwiching a constituent peptide of the protein between a major histocompatibility complex (MHC) molecule and a T cell receptor (TCR). Viruses have evolved means of "camouflaging" themselves, avoiding immune recognition by reducing the MHC and/or TCR binding of their constituent peptides. Computer-driven T cell epitope mapping tools have been used to evaluate the degree to which particular viruses have used this means of avoiding immune response, but most such analyses focus on MHC-facing 'agretopes'. Here we set out a new means of evaluating the TCR faces of viral peptides in addition to their agretopes, integrating evaluations of both sides of the ternary complex in a single analysis. Methods This paper develops what we call the Janus Immunogenicity Score (JIS), bringing together a well-established method for predicting MHC binding, with a novel assessment of the potential for TCR binding based on similarity with self. Intuitively, both good MHC binding and poor self-similarity are required for high immunogenicity (i.e., a robust T effector response). Results Focusing on the class II antigen-processing pathway, we show that the JIS of T effector epitopes and null or regulatory epitopes deposited in a large database of epitopes (Immune Epitope Database) are significantly different. We then show that different types of viruses display significantly different patterns of scores over their constituent peptides, with viruses causing chronic infection (Epstein-Barr and cytomegalovirus) strongly shifted to lower scores relative to those causing acute infection (Ebola and Marburg). Similarly we find distinct patterns among influenza proteins in H1N1 (a strain against which human populations rapidly developed immunity) and H5N1 and H7N9 (highly pathogenic avian flu strains, with significantly greater case mortality rates). Conclusion The Janus Immunogenicity Score, which integrates MHC binding and TCR cross-reactivity, provides a new tool for studying immunogenicity of pathogens and may improve the selection and optimization of antigenic elements for vaccine design.
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111
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Recent progress and challenges in the computer-aided design of inhibitors for influenza A M2 channel proteins. Med Chem Res 2014. [DOI: 10.1007/s00044-014-0964-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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112
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Insight into highly conserved H1 subtype-specific epitopes in influenza virus hemagglutinin. PLoS One 2014; 9:e89803. [PMID: 24587046 PMCID: PMC3935945 DOI: 10.1371/journal.pone.0089803] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Accepted: 01/27/2014] [Indexed: 01/14/2023] Open
Abstract
Influenza viruses continuously undergo antigenic changes with gradual accumulation of mutations in hemagglutinin (HA) that is a major determinant in subtype specificity. The identification of conserved epitopes within specific HA subtypes gives an important clue for developing new vaccines and diagnostics. We produced and characterized nine monoclonal antibodies that showed significant neutralizing activities against H1 subtype influenza viruses, and determined the complex structure of HA derived from a 2009 pandemic virus A/Korea/01/2009 (KR01) and the Fab fragment from H1-specific monoclonal antibody GC0587. The overall structure of the complex was essentially identical to the previously determined KR01 HA-Fab0757 complex structure. Both Fab0587 and Fab0757 recognize readily accessible head regions of HA, revealing broadly shared and conserved antigenic determinants among H1 subtypes. The β-strands constituted by Ser110-Glu115 and Lys169-Lys170 form H1 epitopes with distinct conformations from those of H1 and H3 HA sites. In particular, Glu112, Glu115, Lys169, and Lys171 that are highly conserved among H1 subtype HAs have close contacts with HCDR3 and LCDR3. The differences between Fab0587 and Fab0757 complexes reside mainly in HCDR3 and LCDR3, providing distinct antigenic determinants specific for 1918 pdm influenza strain. Our results demonstrate a potential key neutralizing epitope important for H1 subtype specificity in influenza virus.
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113
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Pooled RNAi screen identifies ubiquitin ligase Itch as crucial for influenza A virus release from the endosome during virus entry. Proc Natl Acad Sci U S A 2013; 110:17516-21. [PMID: 24101521 DOI: 10.1073/pnas.1312374110] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Influenza viruses, like other viruses, rely on host factors to support their life cycle as viral proteins usually "hijack," or collaborate with, cellular proteins to execute their functions. Identification and understanding of these factors can increase the knowledge of molecular mechanisms manipulated by the viruses and facilitate development of antiviral drugs. To this end, we developed a unique genome-wide pooled shRNA screen to search for cellular factors important for influenza A virus (IAV) replication. We identified an E3 ubiquitin ligase, Itch, as an essential factor for an early step in the viral life cycle. In Itch knockdown cells, the incorporation of viral ribonucleoprotein complex into endosomes was normal, but its subsequent release from endosomes and transport to the nucleus was retarded. In addition, upon virus infection, Itch was phosphorylated and recruited to the endosomes, where virus particles were located. Furthermore, Itch interacted with viral M1 protein and ubiquitinated M1 protein. Collectively, our findings unravel a critical role of Itch in mediating IAV release from the endosome and offer insights into the mechanism for IAV uncoating during virus entry. These findings also highlight the feasibility of pooled RNAi screening for exploring the cellular cofactors of lytic viruses.
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114
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Giorda KM, Hebert DN. Viroporins customize host cells for efficient viral propagation. DNA Cell Biol 2013; 32:557-64. [PMID: 23945006 DOI: 10.1089/dna.2013.2159] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Viruses are intracellular parasites that must access the host cell machinery to propagate. Viruses hijack the host cell machinery to help with entry, replication, packaging, and release of progeny to infect new cells. To carry out these diverse functions, viruses often transform the cellular environment using viroporins, a growing class of viral-encoded membrane proteins that promote viral proliferation. Viroporins modify the integrity of host membranes, thereby stimulating the maturation of viral infection, and are critical for virus production and dissemination. Significant advances in molecular and cell biological approaches have helped to uncover some of the roles that viroporins serve in the various stages of the viral life cycle. In this study, the ability of viroporins to modify the cellular environment will be discussed, with particular emphasis on their role in the stepwise progression of the viral life cycle.
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Affiliation(s)
- Kristina M Giorda
- Program in Molecular and Cellular Biology, Department of Biochemistry and Molecular Biology, University of Massachusetts , Amherst, Massachusetts
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115
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Beyleveld G, White KM, Ayllon J, Shaw ML. New-generation screening assays for the detection of anti-influenza compounds targeting viral and host functions. Antiviral Res 2013; 100:120-32. [PMID: 23933115 DOI: 10.1016/j.antiviral.2013.07.018] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2013] [Revised: 07/23/2013] [Accepted: 07/26/2013] [Indexed: 01/08/2023]
Abstract
Current options for influenza antiviral therapy are limited to the neuraminidase inhibitors, and knowledge that high levels of oseltamivir resistance have been seen among previously circulating H1N1 viruses increases the urgency to find new influenza therapeutics. To feed this pipeline, assays that are appropriate for use in high-throughput screens are being developed and are discussed in this review. Particular emphasis is placed on cell-based assays that capture both inhibitors of viral functions as well as the host functions that facilitate optimal influenza virus replication. Success in this area has been fueled by a greater understanding of the genome structure of influenza viruses and the ability to generate replication-competent recombinant viruses that carry a reporter gene, allowing for easy monitoring of viral infection in a high-throughput setting. This article forms part of a symposium in Antiviral Research on "Treatment of influenza: targeting the virus or the host."
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Affiliation(s)
- Grant Beyleveld
- Department of Microbiology and Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
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116
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Raghava S, Giorda KM, Romano FB, Heuck AP, Hebert DN. SV40 late protein VP4 forms toroidal pores to disrupt membranes for viral release. Biochemistry 2013; 52:3939-48. [PMID: 23651212 DOI: 10.1021/bi400036z] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Nonenveloped viruses are generally released from the cell by the timely lysis of host cell membranes. SV40 has been used as a model virus for the study of the lytic nonenveloped virus life cycle. The expression of SV40 VP4 at later times during infection is concomitant with cell lysis. To investigate the role of VP4 in viral release and its mechanism of action, VP4 was expressed and purified from bacteria as a fusion protein for use in membrane disruption assays. Purified VP4 perforated membranes as demonstrated by the release of fluorescent markers encapsulated within large unilamellar vesicles or liposomes. Dynamic light scattering results revealed that VP4 treatment did not cause membrane lysis or change the size of the liposomes. Liposomes encapsulated with 4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-3-indacene-labeled streptavidin were used to show that VP4 formed stable pores in membranes. These VP4 pores had an inner diameter of 1-5 nm. Asymmetrical liposomes containing pyrene-labeled lipids in the outer monolayer were employed to monitor transbilayer lipid diffusion. Consistent with VP4 forming toroidal pore structures in membranes, VP4 induced transbilayer lipid diffusion or lipid flip-flop. Altogether, these studies support a central role for VP4 acting as a viroporin in the disruption of cellular membranes to trigger SV40 viral release by forming toroidal pores that unite the outer and inner leaflets of membrane bilayers.
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Affiliation(s)
- Smita Raghava
- Department of Biochemistry and Molecular Biology, University of Massachusetts , 710 North Pleasant Street, Amherst, Massachusetts 01003, United States
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117
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Yan S, Wu G. Association of combined features of amino acid and protein withcrystallization propensity of proteins fromCytophaga Hutchinsonii. Z KRIST-CRYST MATER 2013. [DOI: 10.1524/zkri.2013.1570] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
AbstractVarious features of amino acids have been so far associated with crystallization propensity of proteins. The majority of features generally represents a certain aspect of individual amino acid, for example, molecular weight of an amino acid. Meanwhile, a small portion of features, which represents a certain aspect of a whole protein, is also associated with crystallization propensity of proteins, such as protein length. Clearly, the features of individual amino acids distinguish themselves from the features of a whole protein. Therefore it would be more rationale to use the features, which combine both features of individual amino acids and a whole protein, to associate crystallization propensity of proteins, because the features of individual amino acids are not subject to amino acids‘ positions in a protein, for instance. In this study, each of three combined features of individual amino acids and a whole protein are associated with crystallization propensity of proteins fromCytophaga Hutchinsoniithrough logistic regression and neural network, and each of 535 features of individual amino acids is also associated with crystallization propensity of the proteins to serve as benchmark. The results show that the combined features have a good relationship with crystallization propensity of proteins fromCytophaga Hutchinsonii. This study provides the information that the combined features can be used for predicting crystallization propensity of protein.
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118
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Gu RX, Liu LA, Wang YH, Xu Q, Wei DQ. Structural Comparison of the Wild-Type and Drug-Resistant Mutants of the Influenza A M2 Proton Channel by Molecular Dynamics Simulations. J Phys Chem B 2013; 117:6042-51. [DOI: 10.1021/jp312396q] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Ruo-Xu Gu
- State Key Laboratory of Microbial
Metabolism and Shanghai Jiao Tong University, Shanghai Minhang District,
200240, China
| | - Limin Angela Liu
- Fred Hutchinson
Cancer Research
Center, Seattle Washington 98109, United States
| | - Yong-Hua Wang
- College of Light Industry and
Food Sciences, South China University of Technology, Guangzhou, 510640,
China
| | - Qin Xu
- State Key Laboratory of Microbial
Metabolism and Shanghai Jiao Tong University, Shanghai Minhang District,
200240, China
| | - Dong-Qing Wei
- State Key Laboratory of Microbial
Metabolism and Shanghai Jiao Tong University, Shanghai Minhang District,
200240, China
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119
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Wanka L, Iqbal K, Schreiner PR. The lipophilic bullet hits the targets: medicinal chemistry of adamantane derivatives. Chem Rev 2013; 113:3516-604. [PMID: 23432396 PMCID: PMC3650105 DOI: 10.1021/cr100264t] [Citation(s) in RCA: 441] [Impact Index Per Article: 40.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Lukas Wanka
- Institute of Organic Chemistry, Justus-Liebig University Giessen, Heinrich-Buff-Ring 58, 35392 Giessen, Germany; Fax +49(641)9934309
- Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, 1050 Forest Hill Road, Staten Island, NY 10314-6399, USA
| | - Khalid Iqbal
- Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, 1050 Forest Hill Road, Staten Island, NY 10314-6399, USA
| | - Peter R. Schreiner
- Institute of Organic Chemistry, Justus-Liebig University Giessen, Heinrich-Buff-Ring 58, 35392 Giessen, Germany; Fax +49(641)9934309
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120
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Tran N, Tran L, Le L. Strategy in structure-based drug design for influenza A virus targeting M2 channel proteins. Med Chem Res 2013. [DOI: 10.1007/s00044-013-0599-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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121
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Tønnessen R, Hauge AG, Hansen EF, Rimstad E, Jonassen CM. Host restrictions of avian influenza viruses: in silico analysis of H13 and H16 specific signatures in the internal proteins. PLoS One 2013; 8:e63270. [PMID: 23646204 PMCID: PMC3639990 DOI: 10.1371/journal.pone.0063270] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2012] [Accepted: 04/02/2013] [Indexed: 12/01/2022] Open
Abstract
Gulls are the primary hosts of H13 and H16 avian influenza viruses (AIVs). The molecular basis for this host restriction is only partially understood. In this study, amino acid sequences from Eurasian gull H13 and H16 AIVs and Eurasian AIVs (non H13 and H16) were compared to determine if specific signatures are present only in the internal proteins of H13 and H16 AIVs, using a bioinformatics approach. Amino acids identified in an initial analysis performed on 15 selected sequences were checked against a comprehensive set of AIV sequences retrieved from Genbank to verify them as H13 and H16 specific signatures. Analysis of protein similarities and prediction of subcellular localization signals were performed to search for possible functions associated with the confirmed signatures. H13 and H16 AIV specific signatures were found in all the internal proteins examined, but most were found in the non-structural protein 1 (NS1) and in the nucleoprotein. A putative functional signature was predicted to be present in the nuclear export protein. Moreover, it was predicted that the NS1 of H13 and H16 AIVs lack one of the nuclear localization signals present in NS1 of other AIV subtypes. These findings suggest that the signatures found in the internal proteins of H13 and H16 viruses are possibly related to host restriction.
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Affiliation(s)
- Ragnhild Tønnessen
- Department of Food Safety and Infection Biology, Norwegian School of Veterinary Science, Oslo, Norway.
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122
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Mutations in Escherichia coli ExbB transmembrane domains identify scaffolding and signal transduction functions and exclude participation in a proton pathway. J Bacteriol 2013; 195:2898-911. [PMID: 23603742 DOI: 10.1128/jb.00017-13] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The TonB system couples cytoplasmic membrane proton motive force (pmf) to active transport of diverse nutrients across the outer membrane. Current data suggest that cytoplasmic membrane proteins ExbB and ExbD harness pmf energy. Transmembrane domain (TMD) interactions between TonB and ExbD allow the ExbD C terminus to modulate conformational rearrangements of the periplasmic TonB C terminus in vivo. These conformational changes somehow allow energization of high-affinity TonB-gated transporters by direct interaction with TonB. While ExbB is essential for energy transduction, its role is not well understood. ExbB has N-terminus-out, C-terminus-in topology with three TMDs. TMDs 1 and 2 are punctuated by a cytoplasmic loop, with the C-terminal tail also occupying the cytoplasm. We tested the hypothesis that ExbB TMD residues play roles in proton translocation. Reassessment of TMD boundaries based on hydrophobic character and residue conservation among distantly related ExbB proteins brought earlier widely divergent predictions into congruence. All TMD residues with potentially function-specific side chains (Lys, Cys, Ser, Thr, Tyr, Glu, and Asn) and residues with probable structure-specific side chains (Trp, Gly, and Pro) were substituted with Ala and evaluated in multiple assays. While all three TMDs were essential, they had different roles: TMD1 was a region through which ExbB interacted with the TonB TMD. TMD2 and TMD3, the most conserved among the ExbB/TolQ/MotA/PomA family, played roles in signal transduction between cytoplasm and periplasm and the transition from ExbB homodimers to homotetramers. Consideration of combined data excludes ExbB TMD residues from direct participation in a proton pathway.
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123
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Zhang Y, Shen H, Zhang M, Li G. Exploring the proton conductance and drug resistance of BM2 channel through molecular dynamics simulations and free energy calculations at different pH conditions. J Phys Chem B 2013; 117:982-8. [PMID: 23286443 DOI: 10.1021/jp309682t] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BM2 channel plays an important role in the replication of influenza virus B. However, few studies attempt to investigate the mechanism of the proton conductance in BM2 channel, as well as the drug resistance of the BM2 channel. The first experimental structure of the BM2 protein channel has recently been solved, enabling us to theoretically study BM2 systems with different protonation states of histidine. By performing molecular dynamics simulations on the BM2 systems with different protonation states of four His19 residues, we provided our understanding of the structure, dynamics, and drug resistance of the BM2 channel. In general, the results of our study and other investigations both have demonstrated that whether the BM2 channel adopts an open or a closed form depends on the protonation state of His19. Meanwhile, we discovered that a drug (amantadine) was unable to enter into the center of the BM2 channel even at a low pH condition probably due to the number of hydrophilic residues of the BM2 channel. Finally, potentials of mean force (PMF) calculations were performed for the drug binding BM2 channel, energetically explaining why the BM2 channel exhibited drug resistance to two inhibitors of the AM2 channel, amantadine and rimantadine.
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Affiliation(s)
- Yuxin Zhang
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China 116023
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124
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Robertson JWF, Kasianowicz JJ, Banerjee S. Analytical Approaches for Studying Transporters, Channels and Porins. Chem Rev 2012; 112:6227-49. [DOI: 10.1021/cr300317z] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Joseph W. F. Robertson
- Physical Measurement Laboratory,
National Institute of Standards and Technology, Gaithersburg, Maryland
20899, United States
| | - John J. Kasianowicz
- Physical Measurement Laboratory,
National Institute of Standards and Technology, Gaithersburg, Maryland
20899, United States
| | - Soojay Banerjee
- National
Institute of Neurological
Disorders and Stroke, Bethesda, Maryland 20824, United States
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125
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Wise HM, Hutchinson EC, Jagger BW, Stuart AD, Kang ZH, Robb N, Schwartzman LM, Kash JC, Fodor E, Firth AE, Gog JR, Taubenberger JK, Digard P. Identification of a novel splice variant form of the influenza A virus M2 ion channel with an antigenically distinct ectodomain. PLoS Pathog 2012; 8:e1002998. [PMID: 23133386 PMCID: PMC3486900 DOI: 10.1371/journal.ppat.1002998] [Citation(s) in RCA: 165] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Accepted: 09/13/2012] [Indexed: 01/25/2023] Open
Abstract
Segment 7 of influenza A virus produces up to four mRNAs. Unspliced transcripts encode M1, spliced mRNA2 encodes the M2 ion channel, while protein products from spliced mRNAs 3 and 4 have not previously been identified. The M2 protein plays important roles in virus entry and assembly, and is a target for antiviral drugs and vaccination. Surprisingly, M2 is not essential for virus replication in a laboratory setting, although its loss attenuates the virus. To better understand how IAV might replicate without M2, we studied the reversion mechanism of an M2-null virus. Serial passage of a virus lacking the mRNA2 splice donor site identified a single nucleotide pseudoreverting mutation, which restored growth in cell culture and virulence in mice by upregulating mRNA4 synthesis rather than by reinstating mRNA2 production. We show that mRNA4 encodes a novel M2-related protein (designated M42) with an antigenically distinct ectodomain that can functionally replace M2 despite showing clear differences in intracellular localisation, being largely retained in the Golgi compartment. We also show that the expression of two distinct ion channel proteins is not unique to laboratory-adapted viruses but, most notably, was also a feature of the 1983 North American outbreak of H5N2 highly pathogenic avian influenza virus. In identifying a 14th influenza A polypeptide, our data reinforce the unexpectedly high coding capacity of the viral genome and have implications for virus evolution, as well as for understanding the role of M2 in the virus life cycle. Influenza A virus is a pathogen capable of infecting a wide range of avian and mammalian hosts, causing seasonal epidemics and pandemics in humans. In recent years, the unexpected coding capacity of the virus has begun to be unravelled, with the identification of three more protein products (PB1-F2, PB1-N40 and PA-X) on top of the 10 viral proteins originally identified 30 years ago. Here, we identify a 14th primary translation product, made from segment 7. Previously established protein products from segment 7 include the matrix (M1) and ion channel (M2) proteins. M2, made from a spliced transcript, has multiple roles in the virus lifecycle including in entry and budding. In a laboratory setting, it is possible to generate M2 deficient viruses, but these are highly attenuated. However, upon serial passage a virus lacking the M2 splice donor site quickly recovered wild type growth properties, without reverting the original mutation. Instead we found a compensatory single nucleotide mutation had upregulated another segment 7 mRNA. This mRNA encoded a novel M2-like protein with a variant extracellular domain, which we called M42. M42 compensated for loss of M2 in tissue culture cells and animals, although it displayed some differences in subcellular localisation. Our study therefore identifies a further novel influenza protein and gives insights into the evolution of the virus.
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MESH Headings
- Alternative Splicing
- Animals
- Birds
- Cell Line, Tumor
- Disease Outbreaks
- Dogs
- Humans
- Influenza A Virus, H5N2 Subtype/genetics
- Influenza A Virus, H5N2 Subtype/metabolism
- Influenza in Birds/epidemiology
- Influenza in Birds/genetics
- Influenza in Birds/metabolism
- Influenza, Human/epidemiology
- Influenza, Human/genetics
- Influenza, Human/metabolism
- Mice
- Mice, Inbred BALB C
- North America/epidemiology
- RNA, Messenger/biosynthesis
- RNA, Messenger/genetics
- RNA, Viral/biosynthesis
- RNA, Viral/genetics
- Viral Matrix Proteins/biosynthesis
- Viral Matrix Proteins/genetics
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Affiliation(s)
- Helen M. Wise
- Division of Virology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom
- The Roslin Institute, University of Edinburgh, Easter Bush, Midlothian, United Kingdom
| | - Edward C. Hutchinson
- Division of Virology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Brett W. Jagger
- Division of Virology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom
- Viral Pathogenesis and Evolution Section, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Amanda D. Stuart
- Division of Virology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Zi H. Kang
- Division of Virology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Nicole Robb
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Louis M. Schwartzman
- Viral Pathogenesis and Evolution Section, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - John C. Kash
- Viral Pathogenesis and Evolution Section, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Ervin Fodor
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Andrew E. Firth
- Division of Virology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Julia R. Gog
- DAMTP, Centre for Mathematical Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Jeffery K. Taubenberger
- Viral Pathogenesis and Evolution Section, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Paul Digard
- Division of Virology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom
- The Roslin Institute, University of Edinburgh, Easter Bush, Midlothian, United Kingdom
- * E-mail:
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126
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Abstract
Viroporins are small virally encoded hydrophobic proteins that oligomerize in the membrane of host cells, leading to the formation of hydrophilic pores. This activity modifies several cellular functions, including membrane permeability, Ca2+ homeostasis, membrane remodelling and glycoprotein trafficking. A classification scheme for viroporins is proposed on the basis of their structure and membrane topology. Thus, class I and class II viroporins are defined according to the number of transmembrane domains in the protein (one and two, respectively), and subclasses are defined according to their orientation in the membrane. The main function of viroporins during viral replication is to participate in virion morphogenesis and release from host cells. In addition, some viroporins are involved in viral entry and genome replication. The structure and activity of several viroporins, such as picornavirus protein 2B (P2B), influenza A virus matrix protein 2 (M2), hepatitis C virus p7 and HIV-1 viral protein U (Vpu), have been analysed in detail. New members of this expanding family of viral proteins have been described, from both RNA and DNA viruses. In addition to having a common general structure, all of these new viroporins have the ability to increase membrane permeability. Viroporins represent ideal targets to block viral replication and the spread of infection. Although a number of selective inhibitors of viroporin ion channels have been analysed in detail, optimized screening systems promise to provide new and more potent antiviral compounds in the near future.
Viroporins belong to a growing family of virally encoded proteins that form aqueous channels in the membranes of host cells. Here, Carrasco and colleagues review the structure and diverse biological functions of these proteins during the viral life cycle, as well as their potential as antiviral therapeutic targets. Viroporins are small, hydrophobic proteins that are encoded by a wide range of clinically relevant animal viruses. When these proteins oligomerize in host cell membranes, they form hydrophilic pores that disrupt a number of physiological properties of the cell. Viroporins are crucial for viral pathogenicity owing to their involvement in several diverse steps of the viral life cycle. Thus, these viral proteins, which include influenza A virus matrix protein 2 (M2), HIV-1 viral protein U (Vpu) and hepatitis C virus p7, represent ideal targets for therapeutic intervention, and several compounds that block their pore-forming activity have been identified. Here, we review recent studies in the field that have advanced our knowledge of the structure and function of this expanding family of viral proteins.
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127
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Jahandideh S, Mahdavi A. RFCRYS: sequence-based protein crystallization propensity prediction by means of random forest. J Theor Biol 2012; 306:115-9. [PMID: 22726810 DOI: 10.1016/j.jtbi.2012.04.028] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Revised: 01/27/2012] [Accepted: 04/24/2012] [Indexed: 01/01/2023]
Abstract
Production of high-quality diffracting crystals is a critical step in determining the 3D structure of a protein by X-ray crystallography. Only 2%-10% of crystallization projects result in high-resolution protein structures. Previously, several computational methods for prediction of protein crystallizability were developed. In this work, we introduce RFCRYS, a Random Forest based method to predict crystallizability of proteins. RFCRYS utilizes mono-, di-, and tri-peptides amino acid compositions, frequencies of amino acids in different physicochemical groups, isoelectric point, molecular weight, and length of protein sequences, from the primary sequences to predict crystallizabillity by using two different databases. RFCRYS was compared with previous methods and the results obtained show that our proposed method using this set of features outperforms existing predictors with higher accuracy, MCC, and Specificity. Especially, our method is characterized by high Specificity of 0.95, which means RFCRYS rarely mispredicts a protein chain to be crystallizable which consequently would be useful for saving time and resources. In conclusion RFCRYS provides accurate crystallizability prediction for a protein chain that can be applied to support crystallization projects getting higher success rate towards obtaining diffraction-quality crystals.
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Affiliation(s)
- Samad Jahandideh
- Department of Biostatistics, Section on Statistical Genetics, University of Alabama at Birmingham, Birmingham, AL, USA.
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128
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Yan S, Wu G. Small Variations Between Species/Subtypes Attributed to Reassortment Evidenced from Polymerase Basic Protein 1 with Other Seven Proteins from Influenza A Virus. Transbound Emerg Dis 2012; 60:110-9. [DOI: 10.1111/j.1865-1682.2012.01323.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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129
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Chang SS, Huang HJ, Chen CYC. Two birds with one stone? Possible dual-targeting H1N1 inhibitors from traditional Chinese medicine. PLoS Comput Biol 2011; 7:e1002315. [PMID: 22215997 PMCID: PMC3245300 DOI: 10.1371/journal.pcbi.1002315] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Accepted: 11/03/2011] [Indexed: 12/20/2022] Open
Abstract
The H1N1 influenza pandemic of 2009 has claimed over 18,000 lives. During this pandemic, development of drug resistance further complicated efforts to control and treat the widespread illness. This research utilizes traditional Chinese medicine Database@Taiwan (TCM Database@Taiwan) to screen for compounds that simultaneously target H1 and N1 to overcome current difficulties with virus mutations. The top three candidates were de novo derivatives of xylopine and rosmaricine. Bioactivity of the de novo derivatives against N1 were validated by multiple machine learning prediction models. Ability of the de novo compounds to maintain CoMFA/CoMSIA contour and form key interactions implied bioactivity within H1 as well. Addition of a pyridinium fragment was critical to form stable interactions in H1 and N1 as supported by molecular dynamics (MD) simulation. Results from MD, hydrophobic interactions, and torsion angles are consistent and support the findings of docking. Multiple anchors and lack of binding to residues prone to mutation suggest that the TCM de novo derivatives may be resistant to drug resistance and are advantageous over conventional H1N1 treatments such as oseltamivir. These results suggest that the TCM de novo derivatives may be suitable candidates of dual-targeting drugs for influenza.
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Affiliation(s)
- Su-Sen Chang
- Laboratory of Computational and Systems Biology, China Medical University, Taichung, Taiwan
| | - Hung-Jin Huang
- Sciences and Chinese Medicine Resources, China Medical University, Taichung, Taiwan
| | - Calvin Yu-Chian Chen
- Laboratory of Computational and Systems Biology, China Medical University, Taichung, Taiwan
- Department of Bioinformatics, Asia University, Taichung, Taiwan
- China Medical University Beigang Hospital, Yunlin, Taiwan
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
- Computational and Systems Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- * E-mail:
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130
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Zhang J, Gao DY, Yearwood J. A novel canonical dual computational approach for prion AGAAAAGA amyloid fibril molecular modeling. J Theor Biol 2011; 284:149-57. [PMID: 21723301 DOI: 10.1016/j.jtbi.2011.06.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Revised: 06/15/2011] [Accepted: 06/17/2011] [Indexed: 12/22/2022]
Abstract
Many experimental studies have shown that the prion AGAAAAGA palindrome hydrophobic region (113-120) has amyloid fibril forming properties and plays an important role in prion diseases. However, due to the unstable, noncrystalline and insoluble nature of the amyloid fibril, to date structural information on AGAAAAGA region (113-120) has been very limited. This region falls just within the N-terminal unstructured region PrP (1-123) of prion proteins. Traditional X-ray crystallography and nuclear magnetic resonance (NMR) spectroscopy experimental methods cannot be used to get its structural information. Under this background, this paper introduces a novel approach of the canonical dual theory to address the 3D atomic-resolution structure of prion AGAAAAGA amyloid fibrils. The novel and powerful canonical dual computational approach introduced in this paper is for the molecular modeling of prion AGAAAAGA amyloid fibrils, and that the optimal atomic-resolution structures of prion AGAAAAGA amyloid fibils presented in this paper are useful for the drive to find treatments for prion diseases in the field of medicinal chemistry. Overall, this paper presents an important method and provides useful information for treatments of prion diseases.
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Affiliation(s)
- Jiapu Zhang
- Centre in Informatics and Applied Optimization, Graduate School of Sciences, Informatics Technology and Engineering, University of Ballarat, Mount Helen, VIC 3353, Australia.
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131
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Optimal atomic-resolution structures of prion AGAAAAGA amyloid fibrils. J Theor Biol 2011; 279:17-28. [DOI: 10.1016/j.jtbi.2011.02.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2010] [Revised: 02/05/2011] [Accepted: 02/16/2011] [Indexed: 11/20/2022]
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132
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Resistance characteristics of influenza to amino-adamantyls. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:547-53. [DOI: 10.1016/j.bbamem.2010.06.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2010] [Revised: 06/14/2010] [Accepted: 06/18/2010] [Indexed: 12/17/2022]
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133
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Teissier E, Penin F, Pécheur EI. Targeting cell entry of enveloped viruses as an antiviral strategy. Molecules 2010; 16:221-50. [PMID: 21193846 PMCID: PMC6259279 DOI: 10.3390/molecules16010221] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Revised: 12/16/2010] [Accepted: 12/24/2010] [Indexed: 12/16/2022] Open
Abstract
The entry of enveloped viruses into their host cells involves several successive steps, each one being amenable to therapeutic intervention. Entry inhibitors act by targeting viral and/or cellular components, through either the inhibition of protein-protein interactions within the viral envelope proteins or between viral proteins and host cell receptors, or through the inhibition of protein-lipid interactions. Interestingly, inhibitors that concentrate into/onto the membrane in order to target a protein involved in the entry process, such as arbidol or peptide inhibitors of the human immunodeficiency virus (HIV), could allow the use of doses compatible with therapeutic requirements. The efficacy of these drugs validates entry as a point of intervention in viral life cycles. Strategies based upon small molecule antiviral agents, peptides, proteins or nucleic acids, would most likely prove efficient in multidrug combinations, in order to inhibit several steps of virus life cycle and prevent disease progression.
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Affiliation(s)
| | | | - Eve-Isabelle Pécheur
- Institut de Biologie et Chimie des Protéines, UMR 5086, Université de Lyon, IFR 128 BioSciences Gerland-Lyon Sud, 69367 Lyon, France; E-Mails: (E.T.); (F.P.)
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Rotavirus disrupts calcium homeostasis by NSP4 viroporin activity. mBio 2010; 1. [PMID: 21151776 PMCID: PMC2999940 DOI: 10.1128/mbio.00265-10] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2010] [Accepted: 10/27/2010] [Indexed: 12/22/2022] Open
Abstract
Many viruses alter intracellular calcium homeostasis. The rotavirus nonstructural protein 4 (NSP4), an endoplasmic reticulum (ER) transmembrane glycoprotein, increases intracellular levels of cytoplasmic Ca2+ ([Ca2+]cyto) through a phospholipase C-independent pathway, which is required for virus replication and morphogenesis. However, the NSP4 domain and mechanism that increases [Ca2+]cyto are unknown. We identified an NSP4 domain (amino acids [aa] 47 to 90) that inserts into membranes and has structural characteristics of viroporins, a class of small hydrophobic viral proteins that disrupt membrane integrity and ion homeostasis to facilitate virus entry, assembly, or release. Mutational analysis showed that NSP4 viroporin activity was mediated by an amphipathic α-helical domain downstream of a conserved lysine cluster. The lysine cluster directed integral membrane insertion of the viroporin domain and was critical for viroporin activity. In epithelial cells, expression of wild-type NSP4 increased the levels of free cytoplasmic Ca2+ by 3.7-fold, but NSP4 viroporin mutants maintained low levels of [Ca2+]cyto, were retained in the ER, and failed to form cytoplasmic vesicular structures, called puncta, which surround viral replication and assembly sites in rotavirus-infected cells. When [Ca2+]cyto was increased pharmacologically with thapsigargin, viroporin mutants formed puncta, showing that elevation of calcium levels and puncta formation are distinct functions of NSP4 and indicating that NSP4 directly or indirectly responds to elevated cytoplasmic calcium levels. NSP4 viroporin activity establishes the mechanism for NSP4-mediated elevation of [Ca2+]cyto, a critical event that regulates rotavirus replication and virion assembly. Rotavirus is the leading cause of viral gastroenteritis in children and young animals. Rotavirus infection and expression of nonstructural protein 4 (NSP4) alone dramatically increase cytosolic calcium, which is essential for replication and assembly of infectious virions. This work identifies the intracellular mechanism by which NSP4 disrupts calcium homeostasis by showing that NSP4 is a viroporin, a class of virus-encoded transmembrane pores. Mutational analyses identified residues critical for viroporin activity. Viroporin mutants did not elevate the levels of cytoplasmic calcium in mammalian cells and were maintained in the endoplasmic reticulum rather than forming punctate vesicular structures that are critical for virus replication and morphogenesis. Pharmacological elevation of cytoplasmic calcium levels rescued puncta formation in viroporin mutants, demonstrating that elevation of calcium levels and puncta formation are distinct NSP4 functions. While viroporins typically function in virus entry or release, elevation of calcium levels by NSP4 viroporin activity may serve as a regulatory function to facilitate virus replication and assembly.
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Pielak RM, Chou JJ. Solution NMR structure of the V27A drug resistant mutant of influenza A M2 channel. Biochem Biophys Res Commun 2010; 401:58-63. [PMID: 20833142 PMCID: PMC3215091 DOI: 10.1016/j.bbrc.2010.09.008] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Accepted: 09/04/2010] [Indexed: 10/19/2022]
Abstract
The M2 protein of influenza A virus forms a proton-selective channel that is required for viral replication. It is the target of the anti-influenza drugs, amantadine and rimantadine. Widespread drug resistant mutants, however, has greatly compromised the effectiveness of these drugs. Here, we report the solution NMR structure of the highly pathogenic, drug resistant mutant V27A. The structure reveals subtle structural differences from wildtype that maybe linked to drug resistance. The V27A mutation significantly decreases hydrophobic packing between the N-terminal ends of the transmembrane helices, which explains the looser, more dynamic tetrameric assembly. The weakened channel assembly can resist drug binding either by destabilizing the rimantadine-binding pocket at Asp44, in the case of the allosteric inhibition model, or by reducing hydrophobic contacts with amantadine in the pore, in the case of the pore-blocking model. Moreover, the V27A structure shows a substantially increased channel opening at the N-terminal end, which may explain the faster proton conduction observed for this mutant. Furthermore, due to the high quality NMR data recorded for the V27A mutant, we were able to determine the structured region connecting the channel domain to the C-terminal amphipathic helices that was not determined in the wildtype structure. The new structural data show that the amphipathic helices are packed much more closely to the channel domain and provide new insights into the proton transfer pathway.
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Affiliation(s)
- Rafal M. Pielak
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
- Program in Biological and Biomedical Sciences, Harvard Medical School, Boston, MA 02115, USA
| | - James J. Chou
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
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