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Emerging Roles of Viroporins Encoded by DNA Viruses: Novel Targets for Antivirals? Viruses 2015; 7:5375-87. [PMID: 26501313 PMCID: PMC4632388 DOI: 10.3390/v7102880] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Revised: 10/02/2015] [Accepted: 10/12/2015] [Indexed: 12/20/2022] Open
Abstract
Studies have highlighted the essential nature of a group of small, highly hydrophobic, membrane embedded, channel-forming proteins in the life cycles of a growing number of RNA viruses. These viroporins mediate the flow of ions and a range of solutes across cellular membranes and are necessary for manipulating a myriad of host processes. As such they contribute to all stages of the virus life cycle. Recent discoveries have identified proteins encoded by the small DNA tumor viruses that display a number of viroporin like properties. This review article summarizes the recent developments in our understanding of these novel viroporins; describes their roles in the virus life cycles and in pathogenesis and speculates on their potential as targets for anti-viral therapeutic intervention.
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102
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Structural and Functional Analysis of Murine Polyomavirus Capsid Proteins Establish the Determinants of Ligand Recognition and Pathogenicity. PLoS Pathog 2015; 11:e1005104. [PMID: 26474293 PMCID: PMC4608799 DOI: 10.1371/journal.ppat.1005104] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 07/22/2015] [Indexed: 11/29/2022] Open
Abstract
Murine polyomavirus (MuPyV) causes tumors of various origins in newborn mice and hamsters. Infection is initiated by attachment of the virus to ganglioside receptors at the cell surface. Single amino acid exchanges in the receptor-binding pocket of the major capsid protein VP1 are known to drastically alter tumorigenicity and spread in closely related MuPyV strains. The virus represents a rare example of differential receptor recognition directly influencing viral pathogenicity, although the factors underlying these differences remain unclear. We performed structural and functional analyses of three MuPyV strains with strikingly different pathogenicities: the low-tumorigenicity strain RA, the high-pathogenicity strain PTA, and the rapidly growing, lethal laboratory isolate strain LID. Using ganglioside deficient mouse embryo fibroblasts, we show that addition of specific gangliosides restores infectability for all strains, and we uncover a complex relationship between virus attachment and infection. We identify a new infectious ganglioside receptor that carries an additional linear [α-2,8]-linked sialic acid. Crystal structures of all three strains complexed with representative oligosaccharides from the three main pathways of ganglioside biosynthesis provide the molecular basis of receptor recognition. All strains bind to a range of sialylated glycans featuring the central [α-2,3]-linked sialic acid present in the established receptors GD1a and GT1b, but the presence of additional sialic acids modulates binding. An extra [α-2,8]-linked sialic acid engages a protein pocket that is conserved among the three strains, while another, [α-2,6]-linked branching sialic acid lies near the strain-defining amino acids but can be accommodated by all strains. By comparing electron density of the oligosaccharides within the binding pockets at various concentrations, we show that the [α-2,8]-linked sialic acid increases the strength of binding. Moreover, the amino acid exchanges have subtle effects on their affinity for the validated receptor GD1a. Our results indicate that both receptor specificity and affinity influence MuPyV pathogenesis. Viruses are obligate intracellular pathogens, and all of them share one crucial step in their life cycle—the attachment to their host cell via cellular receptors, which are usually proteins or carbohydrates. This step is decisive for the selection of target cells and virus entry. In this study, we investigated murine polyomavirus (MuPyV), which attaches to host gangliosides with its major capsid protein, VP1. We have solved the crystal structures of VP1 in complex with previously known interaction partners as well as with the ganglioside GT1a, which we have identified as a novel functional receptor for MuPyV. Earlier studies have shown that different strains with singular amino acid exchanges in the receptor binding pocket of VP1 display altered pathogenicity and viral spread. Our investigations show that, while these exchanges do not abolish binding or significantly alter interaction modes to our investigated carbohydrates, they have subtle effects on glycan affinity. The combination of receptor specificity, abundance, and affinity reveals a much more intricate regulation of pathogenicity than previously believed. Our results exemplify how delicate changes to the receptor binding pocket of MuPyV VP1 are able to drastically alter virus behavior. This system provides a unique example to study how the first step in the life cycle of a virus can dictate its biological properties.
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103
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Pleckaityte M, Bremer CM, Gedvilaite A, Kucinskaite-Kodze I, Glebe D, Zvirbliene A. Construction of polyomavirus-derived pseudotype virus-like particles displaying a functionally active neutralizing antibody against hepatitis B virus surface antigen. BMC Biotechnol 2015; 15:85. [PMID: 26370129 PMCID: PMC4570255 DOI: 10.1186/s12896-015-0203-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 09/04/2015] [Indexed: 11/18/2022] Open
Abstract
Background Virus-like particles (VLPs) can be efficiently produced by heterologous expression of viral structural proteins in yeast. Due to their repetitive structure, VLPs are extensively used for protein engineering and generation of chimeric VLPs with inserted foreign epitopes. Hamster polyomavirus VP1 represents a promising epitope carrier. However, insertion of large sized protein sequences may interfere with its self-assembly competence. The co-expression of polyomavirus capsid protein VP1 with minor capsid protein VP2 or its fusion protein may result in pseudotype VLPs where an intact VP1 protein mediates VLP formation. In the current study, the capacity of VP1 protein to self-assemble to VLPs and interact with the modified VP2 protein has been exploited to generate pseudotype VLPs displaying large-sized antibody molecules. Results Polyomavirus-derived pseudotype VLPs harbouring a surface-exposed functionally active neutralizing antibody specific to hepatitis B virus (HBV) surface antigen (HBsAg) have been generated. The pseudotype VLPs consisting of an intact hamster polyomavirus (HaPyV) major capsid protein VP1 and minor capsid protein VP2 fused with the anti-HBsAg molecule were efficiently produced in yeast Saccharomyces cerevisiae and purified by density-gradient centrifugation. Formation of VLPs was confirmed by electron microscopy. Two types of pseudotype VLPs were generated harbouring either the single-chain fragment variable (scFv) or Fc-engineered scFv on the VLP surface. The antigen-binding activity of the purified pseudotype VLPs was evaluated by ELISA and virus-neutralization assay on HBV-susceptible primary hepatocytes from Tupaia belangeri. Both types of the pseudotype VLPs were functionally active and showed a potent HBV-neutralizing activity comparable to that of the parental monoclonal antibody. The VP2-fused scFv molecules were incorporated into the VLPs with higher efficiency as compared to the VP2-fused Fc-scFv. However, the pseudotype VLPs with displayed VP2-fused Fc-scFv molecule showed higher antigen-binding activity and HBV-neutralizing capacity that might be explained by a better accessibility of the Fc-engineered scFv of the VLP surface. Conclusions Polyomavirus-derived pseudotype VLPs harbouring multiple functionally active antibody molecules with virus-neutralizing capability may represent a novel platform for developing therapeutic tools with a potential application for post-exposure or therapeutic treatment of viral infections.
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Affiliation(s)
- Milda Pleckaityte
- Department of Immunology and Cell Biology, Institute of Biotechnology, Vilnius University, Graciuno 8, LT-02241, Vilnius, Lithuania.
| | - Corinna M Bremer
- Institute of Medical Virology, National Reference Centre for Hepatitis B and D Viruses, German Centre for Infection Research, Justus-Liebig University of Giessen, Schubertstrasse 81, 35392, Giessen, Germany.
| | - Alma Gedvilaite
- Department of Immunology and Cell Biology, Institute of Biotechnology, Vilnius University, Graciuno 8, LT-02241, Vilnius, Lithuania.
| | - Indre Kucinskaite-Kodze
- Department of Immunology and Cell Biology, Institute of Biotechnology, Vilnius University, Graciuno 8, LT-02241, Vilnius, Lithuania.
| | - Dieter Glebe
- Institute of Medical Virology, National Reference Centre for Hepatitis B and D Viruses, German Centre for Infection Research, Justus-Liebig University of Giessen, Schubertstrasse 81, 35392, Giessen, Germany.
| | - Aurelija Zvirbliene
- Department of Immunology and Cell Biology, Institute of Biotechnology, Vilnius University, Graciuno 8, LT-02241, Vilnius, Lithuania.
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104
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Cheng S, Brooks CL. Protein-Protein Interfaces in Viral Capsids Are Structurally Unique. J Mol Biol 2015; 427:3613-3624. [PMID: 26375252 DOI: 10.1016/j.jmb.2015.09.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2015] [Revised: 08/08/2015] [Accepted: 09/04/2015] [Indexed: 01/20/2023]
Abstract
Viral capsids exhibit elaborate and symmetrical architectures of defined sizes and remarkable mechanical properties not seen with cellular macromolecular complexes. Given the uniqueness of the higher-order organization of viral capsid proteins in the virosphere, we explored the question of whether the patterns of protein-protein interactions within viral capsids are distinct from those in generic protein complexes. Our comparative analysis involving a non-redundant set of 551 inter-subunit interfaces in viral capsids from VIPERdb and 20,014 protein-protein interfaces in non-capsid protein complexes from the Protein Data Bank found 418 generic protein-protein interfaces that share similar physicochemical patterns with some protein-protein interfaces in the capsid set, using the program PCalign we developed for comparing protein-protein interfaces. This overlap in the structural space of protein-protein interfaces is significantly small, with a p-value <0.0001, based on a permutation test on the total set of protein-protein interfaces. Furthermore, the generic protein-protein interfaces that bear similarity in their spatial and chemical arrangement with capsid ones are mostly small in size with fewer than 20 interfacial residues, which results from the relatively limited choices of natural design for small interfaces rather than having significant biological implications in terms of functional relationships. We conclude based on this study that protein-protein interfaces in viral capsids are non-representative of patterns in the smaller, more compact cellular protein complexes. Our finding highlights the design principle of building large biological containers from repeated, self-assembling units and provides insights into specific targets for antiviral drug design for improved efficacy.
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Affiliation(s)
- Shanshan Cheng
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI 48109-2218, USA.
| | - Charles L Brooks
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI 48109-2218, USA; Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA; Biophysics Program, University of Michigan, Ann Arbor, MI 48109-1055, USA.
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105
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He K, Ravindran MS, Tsai B. A bacterial toxin and a nonenveloped virus hijack ER-to-cytosol membrane translocation pathways to cause disease. Crit Rev Biochem Mol Biol 2015; 50:477-88. [PMID: 26362261 DOI: 10.3109/10409238.2015.1085826] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A dedicated network of cellular factors ensures that proteins translocated into the endoplasmic reticulum (ER) are folded correctly before they exit this compartment en route to other cellular destinations or for secretion. When proteins misfold, selective ER-resident enzymes and chaperones are recruited to rectify the protein-misfolding problem in order to maintain cellular proteostasis. However, when a protein becomes terminally misfolded, it is ejected into the cytosol and degraded by the proteasome via a pathway called ER-associated degradation (ERAD). Strikingly, toxins and viruses can hijack elements of the ERAD pathway to access the host cytosol and cause infection. This review focuses on emerging data illuminating the molecular mechanisms by which these toxic agents co-opt the ER-to-cytosol translocation process to cause disease.
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Affiliation(s)
- Kaiyu He
- a Department of Cell and Developmental Biology , University of Michigan Medical School , Ann Arbor , MI , USA
| | - Madhu Sudhan Ravindran
- a Department of Cell and Developmental Biology , University of Michigan Medical School , Ann Arbor , MI , USA
| | - Billy Tsai
- a Department of Cell and Developmental Biology , University of Michigan Medical School , Ann Arbor , MI , USA
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106
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Ströh LJ, Gee GV, Blaum BS, Dugan AS, Feltkamp MCW, Atwood WJ, Stehle T. Trichodysplasia spinulosa-Associated Polyomavirus Uses a Displaced Binding Site on VP1 to Engage Sialylated Glycolipids. PLoS Pathog 2015; 11:e1005112. [PMID: 26302170 PMCID: PMC4547793 DOI: 10.1371/journal.ppat.1005112] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 07/27/2015] [Indexed: 12/22/2022] Open
Abstract
Trichodysplasia spinulosa-associated Polyomavirus (TSPyV) was isolated from a patient suffering from trichodysplasia spinulosa, a skin disease that can appear in severely immunocompromised patients. While TSPyV is one of the five members of the polyomavirus family that are directly linked to a human disease, details about molecular recognition events, the viral entry pathway, and intracellular trafficking events during TSPyV infection remain unknown. Here we have used a structure-function approach to shed light on the first steps of TSPyV infection. We established by cell binding and pseudovirus infection studies that TSPyV interacts with sialic acids during attachment and/or entry. Subsequently, we solved high-resolution X-ray structures of the major capsid protein VP1 of TSPyV in complex with three different glycans, the branched GM1 glycan, and the linear trisaccharides α2,3- and α2,6-sialyllactose. The terminal sialic acid of all three glycans is engaged in a unique binding site on TSPyV VP1, which is positioned about 18 Å from established sialic acid binding sites of other polyomaviruses. Structure-based mutagenesis of sialic acid-binding residues leads to reduction in cell attachment and pseudovirus infection, demonstrating the physiological relevance of the TSPyV VP1-glycan interaction. Furthermore, treatments of cells with inhibitors of N-, O-linked glycosylation, and glycosphingolipid synthesis suggest that glycolipids play an important role during TSPyV infection. Our findings elucidate the first molecular recognition events of cellular infection with TSPyV and demonstrate that receptor recognition by polyomaviruses is highly variable not only in interactions with sialic acid itself, but also in the location of the binding site. Viruses engage receptors on their host cell to initiate entry and infection. Members within a virus family are known to target different tissues and hosts and exploit different pathogenic mechanisms due to critical changes in receptor specificity. The human Trichodysplasia spinulosa-associated Polyomavirus (TSPyV) is known to cause a rare skin disease in immunocompromised individuals. The pathogenic mechanism includes hyperproliferation of inner root sheath cells, but molecular determinants underlying the infection and the associated disease remain unknown. Here we applied a structural and functional approach to investigate the recognition events during early infection steps of the virus. We found that TSPyV engages sialic acid receptors but employs a novel binding site on the capsid that is shifted in comparison to other structurally characterized polyomaviruses. Cell-based studies demonstrate the relevance of the observed interaction for attachment and infection and suggest that glycolipids, rather than N- and O-linked glycoproteins, are important for infection. Our findings demonstrate exemplarily that receptor recognition by (polyoma-) viruses is highly variable not only in interactions with sialic acids, but also in the location of the binding site on the capsid, providing insights about structural determinants of receptor and host specificity and evolution of these viruses.
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Affiliation(s)
- Luisa J. Ströh
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Gretchen V. Gee
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island, United States of America
| | - Bärbel S. Blaum
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Aisling S. Dugan
- Department of Natural Sciences, Assumption College, Worcester, Massachusetts, United States of America
| | - Mariet C. W. Feltkamp
- Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Walter J. Atwood
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island, United States of America
- * E-mail: (WJA); (TS)
| | - Thilo Stehle
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
- Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- * E-mail: (WJA); (TS)
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107
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A Non-enveloped Virus Hijacks Host Disaggregation Machinery to Translocate across the Endoplasmic Reticulum Membrane. PLoS Pathog 2015; 11:e1005086. [PMID: 26244546 PMCID: PMC4526233 DOI: 10.1371/journal.ppat.1005086] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Accepted: 07/15/2015] [Indexed: 02/02/2023] Open
Abstract
Mammalian cytosolic Hsp110 family, in concert with the Hsc70:J-protein complex, functions as a disaggregation machinery to rectify protein misfolding problems. Here we uncover a novel role of this machinery in driving membrane translocation during viral entry. The non-enveloped virus SV40 penetrates the endoplasmic reticulum (ER) membrane to reach the cytosol, a critical infection step. Combining biochemical, cell-based, and imaging approaches, we find that the Hsp110 family member Hsp105 associates with the ER membrane J-protein B14. Here Hsp105 cooperates with Hsc70 and extracts the membrane-penetrating SV40 into the cytosol, potentially by disassembling the membrane-embedded virus. Hence the energy provided by the Hsc70-dependent Hsp105 disaggregation machinery can be harnessed to catalyze a membrane translocation event. How non-enveloped viruses penetrate a host membrane to enter cells and cause disease remains an enigmatic step. To infect cells, the non-enveloped SV40 must transport across the ER membrane to reach the cytosol. In this study, we report that a cellular Hsp105-powered disaggregation machinery pulls SV40 into the cytosol, likely by uncoating the ER membrane-penetrating virus. Because this disaggregation machinery is thought to clarify cellular aggregated proteins, we propose that the force generated by this machinery can also be hijacked by a non-enveloped virus to propel its entry into the host.
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108
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Schubert T, Römer W. How synthetic membrane systems contribute to the understanding of lipid-driven endocytosis. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015. [PMID: 26211452 DOI: 10.1016/j.bbamcr.2015.07.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Synthetic membrane systems, such as giant unilamellar vesicles and solid supported lipid bilayers, have widened our understanding of biological processes occurring at or through membranes. Artificial systems are particularly suited to study the inherent properties of membranes with regard to their components and characteristics. This review critically reflects the emerging molecular mechanism of lipid-driven endocytosis and the impact of model membrane systems in elucidating the complex interplay of biomolecules within this process. Lipid receptor clustering induced by binding of several toxins, viruses and bacteria to the plasma membrane leads to local membrane bending and formation of tubular membrane invaginations. Here, lipid shape, and protein structure and valency are the essential parameters in membrane deformation. Combining observations of complex cellular processes and their reconstitution on minimal systems seems to be a promising future approach to resolve basic underlying mechanisms. This article is part of a Special Issue entitled: Mechanobiology.
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Affiliation(s)
- Thomas Schubert
- Faculty of Biology, Albert-Ludwigs-University Freiburg, Schänzlestraße 1, 79104 Freiburg, Germany; BIOSS - Centre for Biological Signalling Studies, Albert-Ludwigs-University Freiburg, Schänzlestraβe 18, 79104 Freiburg, Germany.
| | - Winfried Römer
- Faculty of Biology, Albert-Ludwigs-University Freiburg, Schänzlestraße 1, 79104 Freiburg, Germany; BIOSS - Centre for Biological Signalling Studies, Albert-Ludwigs-University Freiburg, Schänzlestraβe 18, 79104 Freiburg, Germany.
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109
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ERdj5 Reductase Cooperates with Protein Disulfide Isomerase To Promote Simian Virus 40 Endoplasmic Reticulum Membrane Translocation. J Virol 2015; 89:8897-908. [PMID: 26085143 DOI: 10.1128/jvi.00941-15] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 06/08/2015] [Indexed: 12/17/2022] Open
Abstract
UNLABELLED The nonenveloped polyomavirus (PyV) simian virus 40 (SV40) traffics from the cell surface to the endoplasmic reticulum (ER), where it penetrates the ER membrane to reach the cytosol before mobilizing into the nucleus to cause infection. Prior to ER membrane penetration, ER lumenal factors impart structural rearrangements to the virus, generating a translocation-competent virion capable of crossing the ER membrane. Here we identify ERdj5 as an ER enzyme that reduces SV40's disulfide bonds, a reaction important for its ER membrane transport and infection. ERdj5 also mediates human BK PyV infection. This enzyme cooperates with protein disulfide isomerase (PDI), a redox chaperone previously implicated in the unfolding of SV40, to fully stimulate membrane penetration. Negative-stain electron microscopy of ER-localized SV40 suggests that ERdj5 and PDI impart structural rearrangements to the virus. These conformational changes enable SV40 to engage BAP31, an ER membrane protein essential for supporting membrane penetration of the virus. Uncoupling of SV40 from BAP31 traps the virus in ER subdomains called foci, which likely serve as depots from where SV40 gains access to the cytosol. Our study thus pinpoints two ER lumenal factors that coordinately prime SV40 for ER membrane translocation and establishes a functional connection between lumenal and membrane events driving this process. IMPORTANCE PyVs are established etiologic agents of many debilitating human diseases, especially in immunocompromised individuals. To infect cells at the cellular level, this virus family must penetrate the host ER membrane to reach the cytosol, a critical entry step. In this report, we identify two ER lumenal factors that prepare the virus for ER membrane translocation and connect these lumenal events with events on the ER membrane. Pinpointing cellular components necessary for supporting PyV infection should lead to rational therapeutic strategies for preventing and treating PyV-related diseases.
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110
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Emerging structural insights into the function of ionotropic glutamate receptors. Trends Biochem Sci 2015; 40:328-37. [PMID: 25941168 DOI: 10.1016/j.tibs.2015.04.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 04/07/2015] [Accepted: 04/08/2015] [Indexed: 01/16/2023]
Abstract
Ionotropic glutamate receptors (iGluRs) are ligand-gated ion channels that mediate excitatory neurotransmission crucial for brain development and function, including learning and memory formation. Recently a wealth of structural studies on iGluRs including AMPA receptors (AMPARs), kainate receptors, and NMDA receptors (NMDARs) became available. These studies showed structures of non-NMDARs including AMPAR and kainate receptor in various functional states, thereby providing the first visual sense of how non-NMDAR iGluRs may function in the context of homotetramers. Furthermore, they provided the first view of heterotetrameric NMDAR ion channels, and this illuminated the similarities with and differences from non-NMDARs, thus raising a mechanistic distinction between the two groups of iGluRs. We review mechanistic insights into iGluR functions gained through structural studies of multiple groups.
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111
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Herrmann A, Sieben C. Single-virus force spectroscopy unravels molecular details of virus infection. Integr Biol (Camb) 2015; 7:620-32. [PMID: 25923471 DOI: 10.1039/c5ib00041f] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Virus infection is a multistep process that has significant effects on the structure and function of both the virus and the host cell. The first steps of virus replication include cell binding, entry and release of the viral genome. Single-virus force spectroscopy (SVFS) has become a promising tool to understand the molecular details of those steps. SVFS data complemented by biochemical and biophysical, including theoretical modeling approaches provide valuable insights into molecular events that accompany virus infection. Properties of virus-cell interaction as well as structural alterations of the virus essential for infection can be investigated on a quantitative level. Here we review applications of SVFS to virus binding, structure and mechanics. We demonstrate that SVFS offers unexpected new insights not accessible by other methods.
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Affiliation(s)
- Andreas Herrmann
- Humboldt-Universität zu Berlin, Institut für Biologie, Molekulare Biophysik, Invalidenstr. 42, D-10115 Berlin, Germany.
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112
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The Greater Affinity of JC Polyomavirus Capsid for α2,6-Linked Lactoseries Tetrasaccharide c than for Other Sialylated Glycans Is a Major Determinant of Infectivity. J Virol 2015; 89:6364-75. [PMID: 25855729 DOI: 10.1128/jvi.00489-15] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 03/30/2015] [Indexed: 01/04/2023] Open
Abstract
UNLABELLED The human JC polyomavirus (JCPyV) establishes an asymptomatic, persistent infection in the kidneys of the majority of the population and is the causative agent of the fatal demyelinating disease progressive multifocal leukoencephalopathy (PML) in immunosuppressed individuals. The Mad-1 strain of JCPyV, a brain isolate, was shown earlier to require α2,6-linked sialic acid on the lactoseries tetrasaccharide c (LSTc) glycan for attachment to host cells. In contrast, a JCPyV kidney isolate type 3 strain, WT3, has been reported to interact with sialic acid-containing gangliosides, but the role of these glycans in JCPyV infection has remained unclear. To help rationalize these findings and probe the effects of strain-specific differences on receptor binding, we performed a comprehensive analysis of the glycan receptor specificities of these two representative JCPyV strains using high-resolution X-ray crystallography and nuclear magnetic resonance (NMR) spectroscopy, and correlated these data with the results of infectivity assays. We show here that capsid proteins of Mad-1 and WT3 JCPyV can both engage LSTc as well as multiple sialylated gangliosides. However, the binding affinities exhibit subtle differences, with the highest affinity observed for LSTc. Engagement of LSTc is a prerequisite for functional receptor engagement, while the more weakly binding gangliosides are not required for productive infection. Our findings highlight the complexity of virus-carbohydrate interactions and demonstrate that subtle differences in binding affinities, rather than the binding event alone, help determine tissue tropism and viral pathogenesis. IMPORTANCE Viral infection is initiated by attachment to receptors on host cells, and this event plays an important role in viral disease. We investigated the receptor-binding properties of human JC polyomavirus (JCPyV), a virus that resides in the kidneys of the majority of the population and can cause the fatal demyelinating disease progressive multifocal leukoencephalopathy (PML) in the brains of immunosuppressed individuals. JCPyV has been reported to interact with multiple carbohydrate receptors, and we sought to clarify how the interactions between JCPyV and cellular carbohydrate receptors influenced infection. Here we demonstrate that JCPyV can engage numerous sialylated carbohydrate receptors. However, the virus displays preferential binding to LSTc, and only LSTc mediates a productive infection. Our findings demonstrate that subtle differences in binding affinity, rather than receptor engagement alone, are a key determinant of viral infection.
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113
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Fleury MJJ, Nicol JTJ, Samimi M, Arnold F, Cazal R, Ballaire R, Mercey O, Gonneville H, Combelas N, Vautherot JF, Moreau T, Lorette G, Coursaget P, Touzé A. Identification of the neutralizing epitopes of Merkel cell polyomavirus major capsid protein within the BC and EF surface loops. PLoS One 2015; 10:e0121751. [PMID: 25812141 PMCID: PMC4374900 DOI: 10.1371/journal.pone.0121751] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Accepted: 02/04/2015] [Indexed: 11/19/2022] Open
Abstract
Merkel cell polyomavirus (MCPyV) is the first polyomavirus clearly associated with a human cancer, i.e. the Merkel cell carcinoma (MCC). Polyomaviruses are small naked DNA viruses that induce a robust polyclonal antibody response against the major capsid protein (VP1). However, the polyomavirus VP1 capsid protein epitopes have not been identified to date. The aim of this study was to identify the neutralizing epitopes of the MCPyV capsid. For this goal, four VP1 mutants were generated by insertional mutagenesis in the BC, DE, EF and HI loops between amino acids 88-89, 150-151, 189-190, and 296-297, respectively. The reactivity of these mutants and wild-type VLPs was then investigated with anti-VP1 monoclonal antibodies and anti-MCPyV positive human sera. The findings together suggest that immunodominant conformational neutralizing epitopes are present at the surface of the MCPyV VLPs and are clustered within BC and EF loops.
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Affiliation(s)
- Maxime J J Fleury
- L'UNAM Université, Groupe d'Etude des Interactions Hôte-Pathogène, UPRES EA 3142, Université d'Angers, Angers, France
| | - Jérôme T J Nicol
- UMR INRA 1282, Virologie et Immunologie Moléculaire, Faculté des Sciences Pharmaceutiques, Université François Rabelais, PRES Centre-Val de Loire Université, Tours, France
| | - Mahtab Samimi
- UMR INRA 1282, Virologie et Immunologie Moléculaire, Faculté des Sciences Pharmaceutiques, Université François Rabelais, PRES Centre-Val de Loire Université, Tours, France; CHRU de Tours-Hôpital Trousseau, Service de Dermatologie, Tours, France
| | - Françoise Arnold
- UMR INRA 1282, Virologie et Immunologie Moléculaire, Faculté des Sciences Pharmaceutiques, Université François Rabelais, PRES Centre-Val de Loire Université, Tours, France
| | - Raphael Cazal
- UMR INRA 1282, Virologie et Immunologie Moléculaire, Faculté des Sciences Pharmaceutiques, Université François Rabelais, PRES Centre-Val de Loire Université, Tours, France
| | - Raphaelle Ballaire
- UMR INRA 1282, Virologie et Immunologie Moléculaire, Faculté des Sciences Pharmaceutiques, Université François Rabelais, PRES Centre-Val de Loire Université, Tours, France
| | - Olivier Mercey
- UMR INRA 1282, Virologie et Immunologie Moléculaire, Faculté des Sciences Pharmaceutiques, Université François Rabelais, PRES Centre-Val de Loire Université, Tours, France
| | - Hélène Gonneville
- UMR INRA 1282, Virologie et Immunologie Moléculaire, Faculté des Sciences Pharmaceutiques, Université François Rabelais, PRES Centre-Val de Loire Université, Tours, France
| | - Nicolas Combelas
- UMR INRA 1282, Virologie et Immunologie Moléculaire, Faculté des Sciences Pharmaceutiques, Université François Rabelais, PRES Centre-Val de Loire Université, Tours, France
| | | | - Thierry Moreau
- UMR INSERM 1100, Mécanismes Protéolytiques dans l'Inflammation, Faculté de Médecine, Université François Rabelais, PRES Centre-Val de Loire Université, Tours, France
| | - Gérard Lorette
- UMR INRA 1282, Virologie et Immunologie Moléculaire, Faculté des Sciences Pharmaceutiques, Université François Rabelais, PRES Centre-Val de Loire Université, Tours, France; CHRU de Tours-Hôpital Trousseau, Service de Dermatologie, Tours, France
| | - Pierre Coursaget
- Faculté des Sciences Pharmaceutiques, Université François Rabelais, PRES Centre-Val de Loire Université, Tours, France
| | - Antoine Touzé
- UMR INRA 1282, Virologie et Immunologie Moléculaire, Faculté des Sciences Pharmaceutiques, Université François Rabelais, PRES Centre-Val de Loire Université, Tours, France
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Li TC, Iwasaki K, Katano H, Kataoka M, Nagata N, Kobayashi K, Mizutani T, Takeda N, Wakita T, Suzuki T. Characterization of self-assembled virus-like particles of Merkel cell polyomavirus. PLoS One 2015; 10:e0115646. [PMID: 25671590 PMCID: PMC4324643 DOI: 10.1371/journal.pone.0115646] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 11/25/2014] [Indexed: 12/17/2022] Open
Abstract
In our recombinant baculovirus system, VP1 protein of merkel cell polyomavirus (MCPyV), which is implicated as a causative agent in Merkel cell carcinoma, was self-assembled into MCPyV-like particles (MCPyV-LP) with two different sizes in insect cells, followed by being released into the culture medium. DNA molecules of 1.5- to 5-kb, which were derived from host insect cells, were packaged in large, ~50-nm spherical particles but not in small, ~25-nm particles. Structure reconstruction using cryo-electron microscopy showed that large MCPyV-LPs are composed of 72 pentameric capsomeres arranged in a T = 7 icosahedral surface lattice and are 48 nm in diameter. The MCPyV-LPs did not share antigenic determinants with BK- and JC viruses (BKPyV and JCPyV). The VLP-based enzyme immunoassay was applied to investigate age-specific prevalence of MCPyV infection in the general Japanese population aged 1–70 years. While seroprevalence of MCPyV increased with age in children and young individuals, its seropositivity in each age group was lower compared with BKPyV and JCPyV.
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Affiliation(s)
- Tian-Cheng Li
- Department of Virology II, National Institute of Infectious Diseases, Tokyo, Japan
| | - Kenji Iwasaki
- Institute for Protein Research, Osaka University, Osaka, Japan
| | - Harutaka Katano
- Department of Pathology, National Institute of Infectious Diseases, Tokyo, Japan
| | - Michiyo Kataoka
- Department of Pathology, National Institute of Infectious Diseases, Tokyo, Japan
| | - Noriyo Nagata
- Department of Pathology, National Institute of Infectious Diseases, Tokyo, Japan
| | - Kazumi Kobayashi
- Cellular and Structural Physiology Institute, Nagoya University, Nagoya, Japan
| | - Tetsuya Mizutani
- Research and Education center for Prevention of Global Infectious Diseases of Animals, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Naokazu Takeda
- Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Takaji Wakita
- Department of Virology II, National Institute of Infectious Diseases, Tokyo, Japan
| | - Tetsuro Suzuki
- Department of Infectious Diseases, Hamamatsu University School of Medicine, Shizuoka, Japan
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115
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A nucleotide exchange factor promotes endoplasmic reticulum-to-cytosol membrane penetration of the nonenveloped virus simian virus 40. J Virol 2015; 89:4069-79. [PMID: 25653441 DOI: 10.1128/jvi.03552-14] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The nonenveloped simian polyomavirus (PyV) simian virus 40 (SV40) hijacks the endoplasmic reticulum (ER) quality control machinery to penetrate the ER membrane and reach the cytosol, a critical infection step. During entry, SV40 traffics to the ER, where host-induced conformational changes render the virus hydrophobic. The hydrophobic virus binds and integrates into the ER lipid bilayer to initiate membrane penetration. However, prior to membrane transport, the hydrophobic SV40 recruits the ER-resident Hsp70 BiP, which holds the virus in a transport-competent state until it is ready to cross the ER membrane. Here we probed how BiP disengages from SV40 to enable the virus to penetrate the ER membrane. We found that nucleotide exchange factor (NEF) Grp170 induces nucleotide exchange of BiP and releases SV40 from BiP. Importantly, this reaction promotes SV40 ER-to-cytosol transport and infection. The human BK PyV also relies on Grp170 for successful infection. Interestingly, SV40 mobilizes a pool of Grp170 into discrete puncta in the ER called foci. These foci, postulated to represent the ER membrane penetration site, harbor ER components, including BiP, known to facilitate viral ER-to-cytosol transport. Our results thus identify a nucleotide exchange activity essential for catalyzing the most proximal event before ER membrane penetration of PyVs. IMPORTANCE PyVs are known to cause debilitating human diseases. During entry, this virus family, including monkey SV40 and human BK PyV, hijacks ER protein quality control machinery to breach the ER membrane and access the cytosol, a decisive infection step. In this study, we pinpointed an ER-resident factor that executes a crucial role in promoting ER-to-cytosol membrane penetration of PyVs. Identifying a host factor that facilitates entry of the PyV family thus provides additional therapeutic targets to combat PyV-induced diseases.
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The endoplasmic reticulum membrane J protein C18 executes a distinct role in promoting simian virus 40 membrane penetration. J Virol 2015; 89:4058-68. [PMID: 25631089 DOI: 10.1128/jvi.03574-14] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
UNLABELLED The nonenveloped simian virus 40 (SV40) hijacks the three endoplasmic reticulum (ER) membrane-bound J proteins B12, B14, and C18 to escape from the ER into the cytosol en route to successful infection. How C18 controls SV40 ER-to-cytosol membrane penetration is the least understood of these processes. We previously found that SV40 triggers B12 and B14 to reorganize into discrete puncta in the ER membrane called foci, structures postulated to represent the cytosol entry site (C. P. Walczak, M. S. Ravindran, T. Inoue, and B. Tsai, PLoS Pathog 10: e1004007, 2014). We now find that SV40 also recruits C18 to the virus-induced B12/B14 foci. Importantly, the C18 foci harbor membrane penetration-competent SV40, further implicating this structure as the membrane penetration site. Consistent with this, a mutant SV40 that cannot penetrate the ER membrane and promote infection fails to induce C18 foci. C18 also regulates the recruitment of B12/B14 into the foci. In contrast to B14, C18's cytosolic Hsc70-binding J domain, but not the lumenal domain, is essential for its targeting to the foci; this J domain likewise is necessary to support SV40 infection. Knockdown-rescue experiments reveal that C18 executes a role that is not redundant with those of B12/B14 during SV40 infection. Collectively, our data illuminate C18's contribution to SV40 ER membrane penetration, strengthening the idea that SV40-triggered foci are critical for cytosol entry. IMPORTANCE Polyomaviruses (PyVs) cause devastating human diseases, particularly in immunocompromised patients. As this virus family continues to be a significant human pathogen, clarifying the molecular basis of their cellular entry pathway remains a high priority. To infect cells, PyV traffics from the cell surface to the ER, where it penetrates the ER membrane to reach the cytosol. In the cytosol, the virus moves to the nucleus to cause infection. ER-to-cytosol membrane penetration is a critical yet mysterious infection step. In this study, we clarify the role of an ER membrane protein called C18 in mobilizing the simian PyV SV40, a PyV archetype, from the ER into the cytosol. Our findings also support the hypothesis that SV40 induces the formation of punctate structures in the ER membrane, called foci, that serve as the portal for cytosol entry of the virus.
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117
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Modulation of a pore in the capsid of JC polyomavirus reduces infectivity and prevents exposure of the minor capsid proteins. J Virol 2015; 89:3910-21. [PMID: 25609820 DOI: 10.1128/jvi.00089-15] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED JC polyomavirus (JCPyV) infection of immunocompromised individuals results in the fatal demyelinating disease progressive multifocal leukoencephalopathy (PML). The viral capsid of JCPyV is composed primarily of the major capsid protein virus protein 1 (VP1), and pentameric arrangement of VP1 monomers results in the formation of a pore at the 5-fold axis of symmetry. While the presence of this pore is conserved among polyomaviruses, its functional role in infection or assembly is unknown. Here, we investigate the role of the 5-fold pore in assembly and infection of JCPyV by generating a panel of mutant viruses containing amino acid substitutions of the residues lining this pore. Multicycle growth assays demonstrated that the fitness of all mutants was reduced compared to that of the wild-type virus. Bacterial expression of VP1 pentamers containing substitutions to residues lining the 5-fold pore did not affect pentamer assembly or prevent association with the VP2 minor capsid protein. The X-ray crystal structures of selected pore mutants contained subtle changes to the 5-fold pore, and no other changes to VP1 were observed. Pore mutant pseudoviruses were not deficient in assembly, packaging of the minor capsid proteins, or binding to cells or in transport to the host cell endoplasmic reticulum. Instead, these mutant viruses were unable to expose VP2 upon arrival to the endoplasmic reticulum, a step that is critical for infection. This study demonstrated that the 5-fold pore is an important structural feature of JCPyV and that minor modifications to this structure have significant impacts on infectious entry. IMPORTANCE JCPyV is an important human pathogen that causes a severe neurological disease in immunocompromised individuals. While the high-resolution X-ray structure of the major capsid protein of JCPyV has been solved, the importance of a major structural feature of the capsid, the 5-fold pore, remains poorly understood. This pore is conserved across polyomaviruses and suggests either that these viruses have limited structural plasticity in this region or that this pore is important in infection or assembly. Using a structure-guided mutational approach, we showed that modulation of this pore severely inhibits JCPyV infection. These mutants do not appear deficient in assembly or early steps in infectious entry and are instead reduced in their ability to expose a minor capsid protein in the host cell endoplasmic reticulum. Our work demonstrates that the 5-fold pore is an important structural feature for JCPyV.
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118
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Kawano M, Doi K, Fukuda H, Kita Y, Imai K, Inoue T, Enomoto T, Matsui M, Hatakeyama M, Yamaguchi Y, Handa H. SV40 VP1 major capsid protein in its self-assembled form allows VP1 pentamers to coat various types of artificial beads in vitro regardless of their sizes and shapes. ACTA ACUST UNITED AC 2014; 5:105-111. [PMID: 28435806 PMCID: PMC5374266 DOI: 10.1016/j.btre.2014.12.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 11/28/2014] [Accepted: 12/17/2014] [Indexed: 01/17/2023]
Abstract
Monomeric VP1 pentamers of simian virus 40 coat artificial beads larger than natural capsids. Polystyrene beads (100, 200, and 500 nm in diameter) can be covered by VP1 pentamers. Silica beads can also be covered by VP1 pentamers. VP1 pentamers can also coat angular-shaped magnetite-particle and rough-shaped liposomes. The self-reassembly property of VP1 may allow it to coat various artificial beads, regardless of their sizes or shapes.
The icosahedral capsid structure of simian virus 40 (diameter, 45 nm) consists of 72 pentameric subunits, with each subunit formed by five VP1 molecules. Electron microscopy, immuno-gold labeling, and ζ-potential analysis showed that purified recombinant VP1 pentamers covered polystyrene beads measuring 100, 200, and 500 nm in diameter, as well as silica beads. In addition to covering spherical beads, VP1 pentamers covered cubic magnetite beads, as well as the distorted surface structures of liposomes. These findings indicate that VP1 pentamers could coat artificial beads of various shapes and sizes larger than the natural capsid. Technology based on VP1 pentamers may be useful in providing a capsid-like surface for enclosed materials, enhancing their stability and cellular uptake for drug delivery systems.
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Key Words
- Artificial beads
- CMNPs, citrate-coated magnetic nanoparticles
- DMSO, dimethyl sulfoxide
- DOPE, 1,2-dioleoyl-sn-glocero-3-phosphoethanolamine
- DOTAP, N-[1-(2,3-dioleoyloxy)propyl-N,N,N-trimethyl ammonium chloride
- DTT, dithiothreitol
- Drug delivery
- EGF, epidermal growth factor
- EGTA, ethylene glycol-bis(2-aminoethylether)-N,N,N′,N′-tetraacetic acid
- EM, electron microscopy
- NP-40, nonidet P-40
- PLGA, poly-lactic-co-glycolic-acid
- PVA, polyvinyl alcohol
- Polyomavirus
- RCNMV, red clover necrotic mosaic virus
- SV40, simian virus 40
- Simian virus 40
- TEM, transmission electron microscopy
- TEOS, tetraethyl orthosilicate
- VLPs, virus-like particles
- VP1
- VP1 coating
- W/O, water in oil
- W/O/W, water in oil in water
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Affiliation(s)
- Masaaki Kawano
- Department of Molecular Biology, Faculty of Medicine, Saitama Medical University, 38 Morohongo, Moroyama-cho, Iruma-gun, Saitama 350-0495, Japan
| | - Koji Doi
- Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8501, Japan
| | - Hajime Fukuda
- Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8501, Japan
| | - Yoshinori Kita
- Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8501, Japan
| | - Kensuke Imai
- Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8501, Japan
| | - Takamasa Inoue
- Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8501, Japan
| | - Teruya Enomoto
- Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8501, Japan
| | - Masanori Matsui
- Department of Microbiology, Faculty of Medicine, Saitama Medical University, 38 Morohongo, Moroyama-cho, Iruma-gun, Saitama 350-0495, Japan
| | - Mamoru Hatakeyama
- Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8501, Japan
| | - Yuki Yamaguchi
- Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8501, Japan
| | - Hiroshi Handa
- Department of Nanoparticle Translational Research, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, Tokyo 160-8402, Japan
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Abstract
When I entered graduate school in 1963, the golden age of molecular biology had just begun, and myoglobin was the only protein with a known high-resolution structure. The romance of working out the structure of a virus by X-ray crystallography nonetheless captured both my imagination and the ensuing 15 years of my scientific life, during which "protein crystallography" began to morph into "structural biology." The course of the research recounted here follows the broader, 50-year trajectory of structural biology, as I could rarely resist opportunities to capitalize on new technologies when they opened some interesting part of biology to three-dimensional rigor. That fascination shows no sign of subsiding.
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Affiliation(s)
- Stephen C Harrison
- Harvard Medical School, Boston Children's Hospital, and Howard Hughes Medical Institute, Boston, Massachusetts 02115;
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Kaplan R, Klobušický J, Pandey S, Gracias DH, Menon G. Building polyhedra by self-assembly: theory and experiment. ARTIFICIAL LIFE 2014; 20:409-439. [PMID: 25148546 DOI: 10.1162/artl_a_00144] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We investigate the utility of a mathematical framework based on discrete geometry to model biological and synthetic self-assembly. Our primary biological example is the self-assembly of icosahedral viruses; our synthetic example is surface-tension-driven self-folding polyhedra. In both instances, the process of self-assembly is modeled by decomposing the polyhedron into a set of partially formed intermediate states. The set of all intermediates is called the configuration space, pathways of assembly are modeled as paths in the configuration space, and the kinetics and yield of assembly are modeled by rate equations, Markov chains, or cost functions on the configuration space. We review an interesting interplay between biological function and mathematical structure in viruses in light of this framework. We discuss in particular: (i) tiling theory as a coarse-grained description of all-atom models; (ii) the building game-a growth model for the formation of polyhedra; and (iii) the application of these models to the self-assembly of the bacteriophage MS2. We then use a similar framework to model self-folding polyhedra. We use a discrete folding algorithm to compute a configuration space that idealizes surface-tension-driven self-folding and analyze pathways of assembly and dominant intermediates. These computations are then compared with experimental observations of a self-folding dodecahedron with side 300 μm. In both models, despite a combinatorial explosion in the size of the configuration space, a few pathways and intermediates dominate self-assembly. For self-folding polyhedra, the dominant intermediates have fewer degrees of freedom than comparable intermediates, and are thus more rigid. The concentration of assembly pathways on a few intermediates with distinguished geometric properties is biologically and physically important, and suggests deeper mathematical structure.
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121
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Genome analysis of non-human primate polyomaviruses. INFECTION GENETICS AND EVOLUTION 2014; 26:283-94. [DOI: 10.1016/j.meegid.2014.05.030] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Revised: 05/26/2014] [Accepted: 05/27/2014] [Indexed: 12/14/2022]
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122
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JC polyomavirus attachment, entry, and trafficking: unlocking the keys to a fatal infection. J Neurovirol 2014; 21:601-13. [PMID: 25078361 DOI: 10.1007/s13365-014-0272-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 06/05/2014] [Accepted: 06/30/2014] [Indexed: 10/25/2022]
Abstract
The human JC polyomavirus (JCPyV) causes a lifelong persistent infection in the reno-urinary tract in the majority of the adult population worldwide. In healthy individuals, infection is asymptomatic, while in immunocompromised individuals, the virus can spread to the central nervous system and cause a fatal demyelinating disease known as progressive multifocal leukoencephalopathy (PML). There are currently very few treatment options for this rapidly progressing and devastating disease. Understanding the basic biology of JCPyV-host cell interactions is critical for the development of therapeutic strategies to prevent or treat PML. Research in our laboratory has focused on gaining a detailed mechanistic understanding of the initial steps in the JCPyV life cycle in order to define how JCPyV selectively targets cells in the kidney and brain. JCPyV requires sialic acids to attach to host cells and initiate infection, and JCPyV demonstrates specificity for the oligosaccharide lactoseries tetrasaccharide c (LSTc) with an α2,6-linked sialic acid. Following viral attachment, JCPyV entry is facilitated by the 5-hydroxytryptamine (5-HT)2 family of serotonin receptors via clathrin-dependent endocytosis. JCPyV then undergoes retrograde transport to the endoplasmic reticulum (ER) where viral disassembly begins. A novel retrograde transport inhibitor termed Retro-2(cycl) prevents trafficking of JCPyV to the ER and inhibits both initial virus infection and infectious spread in cell culture. Understanding the molecular mechanisms by which JCPyV establishes infection will open up new avenues for the prevention or treatment of virus-induced disease.
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123
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Bilkova E, Forstova J, Abrahamyan L. Coat as a dagger: the use of capsid proteins to perforate membranes during non-enveloped DNA viruses trafficking. Viruses 2014; 6:2899-937. [PMID: 25055856 PMCID: PMC4113798 DOI: 10.3390/v6072899] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 07/09/2014] [Accepted: 07/14/2014] [Indexed: 01/24/2023] Open
Abstract
To get access to the replication site, small non-enveloped DNA viruses have to cross the cell membrane using a limited number of capsid proteins, which also protect the viral genome in the extracellular environment. Most of DNA viruses have to reach the nucleus to replicate. The capsid proteins involved in transmembrane penetration are exposed or released during endosomal trafficking of the virus. Subsequently, the conserved domains of capsid proteins interact with cellular membranes and ensure their efficient permeabilization. This review summarizes our current knowledge concerning the role of capsid proteins of small non-enveloped DNA viruses in intracellular membrane perturbation in the early stages of infection.
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Affiliation(s)
- Eva Bilkova
- Department of Genetics and Microbiology, Faculty of Science, Charles University in Prague, Vinicna 5, 12844, Prague 2, Czech Republic.
| | - Jitka Forstova
- Department of Genetics and Microbiology, Faculty of Science, Charles University in Prague, Vinicna 5, 12844, Prague 2, Czech Republic.
| | - Levon Abrahamyan
- Department of Genetics and Microbiology, Faculty of Science, Charles University in Prague, Vinicna 5, 12844, Prague 2, Czech Republic.
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124
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Structure analysis of the major capsid proteins of human polyomaviruses 6 and 7 reveals an obstructed sialic acid binding site. J Virol 2014; 88:10831-9. [PMID: 25008942 DOI: 10.1128/jvi.01084-14] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
UNLABELLED Human polyomavirus 6 (HPyV6) and HPyV7 are commonly found on human skin. We have determined the X-ray structures of their major capsid protein, VP1, at resolutions of 1.8 and 1.7 Å, respectively. In polyomaviruses, VP1 commonly determines antigenicity as well as cell-surface receptor specificity, and the protein is therefore linked to attachment, tropism, and ultimately, viral pathogenicity. The structures of HPyV6 and HPyV7 VP1 reveal uniquely elongated loops that cover the bulk of the outer virion surfaces, obstructing a groove that binds sialylated glycan receptors in many other polyomaviruses. In support of this structural observation, interactions of VP1 with α2,3- and α2,6-linked sialic acids could not be detected in solution by nuclear magnetic resonance spectroscopy. Single-cell binding studies indicate that sialylated glycans are likely not required for initial attachment to cultured human cells. Our findings establish distinct antigenic properties of HPyV6 and HPyV7 capsids and indicate that these two viruses engage nonsialylated receptors. IMPORTANCE Eleven new human polyomaviruses, including the skin viruses HPyV6 and HPyV7, have been identified during the last decade. In contrast to better-studied polyomaviruses, the routes of infection, cell tropism, and entry pathways of many of these new viruses remain largely mysterious. Our high-resolution X-ray structures of major capsid proteins VP1 from HPyV6 and from HPyV7 reveal critical differences in surface morphology from those of all other known polyomavirus structures. A groove that engages specific sialic acid-containing glycan receptors in related polyomaviruses is obstructed, and VP1 of HPyV6 and HPyV7 does not interact with sialylated compounds in solution or on cultured human cells. A comprehensive comparison with other structurally characterized polyomavirus VP1 proteins enhances our understanding of molecular determinants that underlie receptor specificity, antigenicity, and, ultimately, pathogenicity within the polyomavirus family and highlight the need for structure-based analysis to better define phylogenetic relationships within the growing polyomavirus family and perhaps also for other viruses.
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125
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Abstract
N-Methyl-D-aspartate (NMDA) receptors belong to the family of ionotropic glutamate receptors, which mediate most excitatory synaptic transmission in mammalian brains. Calcium permeation triggered by activation of NMDA receptors is the pivotal event for initiation of neuronal plasticity. Here, we show the crystal structure of the intact heterotetrameric GluN1-GluN2B NMDA receptor ion channel at 4 angstroms. The NMDA receptors are arranged as a dimer of GluN1-GluN2B heterodimers with the twofold symmetry axis running through the entire molecule composed of an amino terminal domain (ATD), a ligand-binding domain (LBD), and a transmembrane domain (TMD). The ATD and LBD are much more highly packed in the NMDA receptors than non-NMDA receptors, which may explain why ATD regulates ion channel activity in NMDA receptors but not in non-NMDA receptors.
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Affiliation(s)
- Erkan Karakas
- Cold Spring Harbor Laboratory, W. M. Keck Structural Biology Laboratory, One Bungtown Road, Cold Spring Harbor, NY 11724, USA
| | - Hiro Furukawa
- Cold Spring Harbor Laboratory, W. M. Keck Structural Biology Laboratory, One Bungtown Road, Cold Spring Harbor, NY 11724, USA.
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126
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Xue B, Blocquel D, Habchi J, Uversky AV, Kurgan L, Uversky VN, Longhi S. Structural disorder in viral proteins. Chem Rev 2014; 114:6880-911. [PMID: 24823319 DOI: 10.1021/cr4005692] [Citation(s) in RCA: 140] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Bin Xue
- Department of Cell Biology, Microbiology and Molecular Biology, College of Fine Arts and Sciences, and ‡Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida , Tampa, Florida 33620, United States
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Baron HR, Howe L, Varsani A, Doneley RJT. Disease screening of three breeding populations of adult exhibition budgerigars (Melopsittacus undulatus) in New Zealand reveals a high prevalence of a novel polyomavirus and avian malaria infection. Avian Dis 2014; 58:111-7. [PMID: 24758122 DOI: 10.1637/10604-063013-reg.1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Disease surveillance is vital to the management of New Zealand's endemic and threatened avian species. Three infectious agents that are potential threats to New Zealand's endemic birds include avian polyomavirus (APV), beak and feather disease virus (BFDV), and avian malaria. All three agents have been reported in New Zealand; however, possible reservoir populations have not been identified. In this communication, we report the first study of APV, BFDV, and avian malaria in introduced adult exhibition budgerigars (Melopsittacus undulatus) in New Zealand. Blood samples were collected from 90 living adult budgerigars from three breeding locations in the North Island of New Zealand. An overall APV prevalence of 22% was determined using a broad-spectrum nested PCR that amplified the major capsid protein VP1 gene of polyomavirus. Phylogenetic analysis of the VP1 gene revealed a unique isolate of APV, which had a sequence divergence of 32% to previously reported budgerigar fledgling disease strains and 33% to the recently reported New Zealand finch isolate. All of the budgerigars sampled were found to be PCR negative for BFDV, and an overall prevalence of 30% was detected by PCR for avian malaria. Sequencing revealed the presence of ubiquitous malarial strains and also the potentially destructive Plasmodium relictum strain. The results of this study suggest that both APV and avian malaria are present in New Zealand adult budgerigars, and our study highlights the need for further studies to determine whether these pathogens in captive bird populations may be a threat or spill over into New Zealand's endemic and threatened avifauna and whether prevention and control methods need to be implemented.
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128
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Walczak CP, Ravindran MS, Inoue T, Tsai B. A cytosolic chaperone complexes with dynamic membrane J-proteins and mobilizes a nonenveloped virus out of the endoplasmic reticulum. PLoS Pathog 2014; 10:e1004007. [PMID: 24675744 PMCID: PMC3968126 DOI: 10.1371/journal.ppat.1004007] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Accepted: 02/02/2014] [Indexed: 11/18/2022] Open
Abstract
Nonenveloped viruses undergo conformational changes that enable them to bind to, disrupt, and penetrate a biological membrane leading to successful infection. We assessed whether cytosolic factors play any role in the endoplasmic reticulum (ER) membrane penetration of the nonenveloped SV40. We find the cytosolic SGTA-Hsc70 complex interacts with the ER transmembrane J-proteins DnaJB14 (B14) and DnaJB12 (B12), two cellular factors previously implicated in SV40 infection. SGTA binds directly to SV40 and completes ER membrane penetration. During ER-to-cytosol transport of SV40, SGTA disengages from B14 and B12. Concomitant with this, SV40 triggers B14 and B12 to reorganize into discrete foci within the ER membrane. B14 must retain its ability to form foci and interact with SGTA-Hsc70 to promote SV40 infection. Our results identify a novel role for a cytosolic chaperone in the membrane penetration of a nonenveloped virus and raise the possibility that the SV40-induced foci represent cytosol entry sites.
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Affiliation(s)
- Christopher Paul Walczak
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- Cellular and Molecular Biology Graduate Program, Ann Arbor, Michigan, United States of America
| | - Madhu Sudhan Ravindran
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Takamasa Inoue
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Billy Tsai
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- * E-mail:
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129
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Crystallographic and glycan microarray analysis of human polyomavirus 9 VP1 identifies N-glycolyl neuraminic acid as a receptor candidate. J Virol 2014; 88:6100-11. [PMID: 24648448 DOI: 10.1128/jvi.03455-13] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
UNLABELLED Human polyomavirus 9 (HPyV9) is a closely related homologue of simian B-lymphotropic polyomavirus (LPyV). In order to define the architecture and receptor binding properties of HPyV9, we solved high-resolution crystal structures of its major capsid protein, VP1, in complex with three putative oligosaccharide receptors identified by glycan microarray screening. Comparison of the properties of HPyV9 VP1 with the known structure and glycan-binding properties of LPyV VP1 revealed that both viruses engage short sialylated oligosaccharides, but small yet important differences in specificity were detected. Surprisingly, HPyV9 VP1 preferentially binds sialyllactosamine compounds terminating in 5-N-glycolyl neuraminic acid (Neu5Gc) over those terminating in 5-N-acetyl neuraminic acid (Neu5Ac), whereas LPyV does not exhibit such a preference. The structural analysis demonstrated that HPyV9 makes specific contacts, via hydrogen bonds, with the extra hydroxyl group present in Neu5Gc. An equivalent hydrogen bond cannot be formed by LPyV VP1. IMPORTANCE The most common sialic acid in humans is 5-N-acetyl neuraminic acid (Neu5Ac), but various modifications give rise to more than 50 different sialic acid variants that decorate the cell surface. Unlike most mammals, humans cannot synthesize the sialic acid variant 5-N-glycolyl neuraminic acid (Neu5Gc) due to a gene defect. Humans can, however, still acquire this compound from dietary sources. The role of Neu5Gc in receptor engagement and in defining viral tropism is only beginning to emerge, and structural analyses defining the differences in specificity for Neu5Ac and Neu5Gc are still rare. Using glycan microarray screening and high-resolution protein crystallography, we have examined the receptor specificity of a recently discovered human polyomavirus, HPyV9, and compared it to that of the closely related simian polyomavirus LPyV. Our study highlights critical differences in the specificities of both viruses, contributing to an enhanced understanding of the principles that underlie pathogen selectivity for modified sialic acids.
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130
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Saccardo P, Rodríguez-Carmona E, Villaverde A, Ferrer-Miralles N. Effect of the DnaK chaperone on the conformational quality of JCV VP1 virus-like particles produced inEscherichia coli. Biotechnol Prog 2014; 30:744-8. [DOI: 10.1002/btpr.1879] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 02/20/2014] [Indexed: 12/17/2022]
Affiliation(s)
- Paolo Saccardo
- Inst. de Biotecnologia i de Biomedicina and Dept. de Genètica i de Microbiologia; Universitat Autònoma de Barcelona and CIBER en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN); Bellaterra Barcelona 08193 Spain
| | - Escarlata Rodríguez-Carmona
- Inst. de Biotecnologia i de Biomedicina and Dept. de Genètica i de Microbiologia; Universitat Autònoma de Barcelona and CIBER en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN); Bellaterra Barcelona 08193 Spain
| | - Antonio Villaverde
- Inst. de Biotecnologia i de Biomedicina and Dept. de Genètica i de Microbiologia; Universitat Autònoma de Barcelona and CIBER en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN); Bellaterra Barcelona 08193 Spain
| | - Neus Ferrer-Miralles
- Inst. de Biotecnologia i de Biomedicina and Dept. de Genètica i de Microbiologia; Universitat Autònoma de Barcelona and CIBER en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN); Bellaterra Barcelona 08193 Spain
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131
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Simon C, Klose T, Herbst S, Han BG, Sinz A, Glaeser RM, Stubbs MT, Lilie H. Disulfide linkage and structure of highly stable yeast-derived virus-like particles of murine polyomavirus. J Biol Chem 2014; 289:10411-10418. [PMID: 24567335 DOI: 10.1074/jbc.m113.484162] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
VP1 is the major coat protein of murine polyomavirus and forms virus-like particles (VLPs) in vitro. VLPs consist of 72 pentameric VP1 subunits held together by a terminal clamp structure that is further stabilized by disulfide bonds and chelation of calcium ions. Yeast-derived VLPs (yVLPs) assemble intracellularly in vivo during recombinant protein production. These in vivo assembled yVLPs differ in several properties from VLPs assembled in vitro from bacterially produced pentamers. We found several intermolecular disulfide linkages in yVLPs involving 5 of the 6 cysteines of VP1 (Cys(115)-Cys(20), Cys(12)-Cys(20), Cys(16)-Cys(16), Cys(12)/ Cys(16)-Cys(115), and Cys(274)-Cys(274)), indicating a highly coordinated disulfide network within the in vivo assembled particles involving the N-terminal region of VP1. Cryoelectron microscopy revealed structured termini not resolved in the published crystal structure of the bacterially expressed VLP that appear to clamp the pentameric subunits together. These structural features are probably the reason for the observed higher stability of in vivo assembled yVLPs compared with in vitro assembled bacterially expressed VLPs as monitored by increased thermal stability, higher resistance to trypsin cleavage, and a higher activation enthalpy of the disassembly reaction. This high stability is decreased following disassembly of yVLPs and subsequent in vitro reassembly, suggesting a role for cellular components in optimal assembly.
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Affiliation(s)
- Claudia Simon
- Institute of Biochemistry and Biotechnology, Martin-Luther-University Halle-Wittenberg, Kurt-Mothes Strasse 03, 06120 Halle, Germany
| | - Thomas Klose
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907
| | - Sabine Herbst
- Institute of Pharmacy, Martin-Luther-University Halle-Wittenberg, Wolfgang-Langenbeck Strasse 04, 06120 Halle, Germany
| | - Bong Gyoon Han
- Life Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720
| | - Andrea Sinz
- Institute of Pharmacy, Martin-Luther-University Halle-Wittenberg, Wolfgang-Langenbeck Strasse 04, 06120 Halle, Germany
| | - Robert M Glaeser
- Life Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720
| | - Milton T Stubbs
- Institute of Biochemistry and Biotechnology, Martin-Luther-University Halle-Wittenberg, Kurt-Mothes Strasse 03, 06120 Halle, Germany
| | - Hauke Lilie
- Institute of Biochemistry and Biotechnology, Martin-Luther-University Halle-Wittenberg, Kurt-Mothes Strasse 03, 06120 Halle, Germany.
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132
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Li F, Chen H, Ma L, Zhou K, Zhang ZP, Meng C, Zhang XE, Wang Q. Insights into stabilization of a viral protein cage in templating complex nanoarchitectures: roles of disulfide bonds. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2014; 10:536-543. [PMID: 24014233 DOI: 10.1002/smll.201300860] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Revised: 07/28/2013] [Indexed: 06/02/2023]
Abstract
As a typical protein nanostructure, virus-based nanoparticle (VNP) of simian virus 40 (SV40), which is composed of pentamers of the major capsid protein of SV40 (VP1), has been successfully employed in guiding the assembly of different nanoparticles (NPs) into predesigned nanostructures with considerable stability. However, the stabilization mechanism of SV40 VNP remains unclear. Here, the importance of inter-pentamer disulfide bonds between cysteines in the stabilization of quantum dot (QD)-containing VNPs (VNP-QDs) is comprehensively investigated by constructing a series of VP1 mutants of cysteine to serine. Although the presence of a QD core can greatly enhance the assembly and stability of SV40 VNPs, disulfide bonds are vital to stability of VNP-QDs. Cysteine at position 9 (C9) and C104 contribute most of the disulfide bonds and play essential roles in determining the stability of SV40 VNPs as templates to guide assembly of complex nanoarchitectures. These results provide insightful clues to understanding the robustness of SV40 VNPs in organizing suprastructures of inorganic NPs. It is expected that these findings will help guide the future design and construction of protein-based functional nanostructures.
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Affiliation(s)
- Feng Li
- Suzhou Key Laboratory of Nanomedical Characterization, Division of Nanobiomedicine and i-Lab, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, 215123, China
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133
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Dent KC, Thompson R, Barker AM, Hiscox JA, Barr JN, Stockley PG, Ranson NA. The asymmetric structure of an icosahedral virus bound to its receptor suggests a mechanism for genome release. Structure 2014; 21:1225-34. [PMID: 23810697 PMCID: PMC3701328 DOI: 10.1016/j.str.2013.05.012] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 04/23/2013] [Accepted: 05/07/2013] [Indexed: 11/23/2022]
Abstract
Simple, spherical RNA viruses have well-understood, symmetric protein capsids, but little structural information is available for their asymmetric components, such as minor proteins and their genomes, which are vital for infection. Here, we report an asymmetric structure of bacteriophage MS2, attached to its receptor, the F-pilus. Cryo-electron tomography and subtomographic averaging of such complexes result in a structure containing clear density for the packaged genome, implying that the conformation of the genome is the same in each virus particle. The data also suggest that the single-copy viral maturation protein breaks the symmetry of the capsid, occupying a position that would be filled by a coat protein dimer in an icosahedral shell. This capsomere can thus fulfill its known biological roles in receptor and genome binding and suggests an exit route for the genome during infection. The asymmetric structure of a virus receptor complex is described The density for ordered genomic RNA was observed in the structure Viral maturation protein was visualized
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Affiliation(s)
- Kyle C Dent
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
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134
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Li F, Wang Q. Fabrication of nanoarchitectures templated by virus-based nanoparticles: strategies and applications. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2014; 10:230-245. [PMID: 23996911 DOI: 10.1002/smll.201301393] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 07/05/2013] [Indexed: 06/02/2023]
Abstract
Biomolecular nanostructures in nature are drawing increasing interests in the field of materials sciences. As a typical group of them, virus-based nanoparticles (VNPs), which are nanocages or nanorods assembled from capsid proteins of viruses, have been widely exploited as templates to guide the fabrication of complex nanoarchitectures (NAs), because of their appropriate sizes (ca. 20-200 nm), homogeneity, addressable functionalization, facile modification via chemical and genetic routes, and convenient preparation. Foreign materials can be positioned in the inner cavity or on the outer surface of VNPs, through either direct synthesis or assembling preformed nanomaterials. Simultaneous use of the inner and outer space of VNPs facilitates integration of multiple functionalities in a single NA. This review briefly summarizes the strategies for fabrication of NAs templated by VNPs and wide applications of these NAs in fields of catalysis, energy, biomedicine, and nanophotonics, etc.
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Affiliation(s)
- Feng Li
- Suzhou Key Laboratory of Nanobiomedical Characterization, Division of Nanobiomedicine and i-Lab, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, 215123, China
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135
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Yamaguchi H, Kobayashi S, Maruyama J, Sasaki M, Takada A, Kimura T, Sawa H, Orba Y. Role of the C-terminal region of vervet monkey polyomavirus 1 VP1 in virion formation. J Vet Med Sci 2014; 76:637-44. [PMID: 24419975 PMCID: PMC4073331 DOI: 10.1292/jvms.13-0568] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Recently, we detected novel vervet monkey polyomavirus 1 (VmPyV) in a vervet monkey.
Among amino acid sequences of major capsid protein VP1s of other polyomaviruses, VmPyV VP1
is the longest with additional amino acid residues in the C-terminal region. To examine
the role of VmPyV VP1 in virion formation, we generated virus-like particles (VLPs) of
VmPyV VP1, because VLP is a useful tool for the investigation of the morphological
characters of polyomavirus virions. After the full-length VmPyV VP1 was subcloned into a
mammalian expression plasmid, the plasmid was transfected into human embryonic kidney 293T
(HEK293T) cells. Thereafter, VmPyV VLPs were purified from the cell lysates of the
transfected cells via sucrose gradient sedimentation. Electron microscopic analyses
revealed that VmPyV VP1 forms VLPs with a diameter of approximately 50 nm that are
exclusively localized in cell nuclei. Furthermore, we generated VLPs consisting of the
deletion mutant VmPyV VP1 (ΔC VP1) lacking the C-terminal 116 amino acid residues and
compared its VLP formation efficiency and morphology to those of VLPs from wild-type VmPyV
VP1 (WT VP1). WT and ΔC VP1 VLPs were similar in size, but the number of ΔC VP1 VLPs was
much lower than that of WT VP1 VLPs in VP1-expressing HEK293T cells. These results suggest
that the length of VP1 is unrelated to virion morphology; however, the C-terminal region
of VmPyV VP1 affects the efficiency of its VLP formation.
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Affiliation(s)
- Hiroki Yamaguchi
- Division of Molecular Pathobiology, Research Center for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido 001-0020, Japan
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136
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Kawano M, Matsui M, Handa H. SV40 virus-like particles as an effective delivery system and its application to a vaccine carrier. Expert Rev Vaccines 2014; 12:199-210. [DOI: 10.1586/erv.12.149] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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137
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Kler S, Wang JCY, Dhason M, Oppenheim A, Zlotnick A. Scaffold properties are a key determinant of the size and shape of self-assembled virus-derived particles. ACS Chem Biol 2013; 8:2753-61. [PMID: 24093474 DOI: 10.1021/cb4005518] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Controlling the geometry of self-assembly will enable a greater diversity of nanoparticles than now available. Viral capsid proteins, one starting point for investigating self-assembly, have evolved to form regular particles. The polyomavirus SV40 assembles from pentameric subunits and can encapsidate anionic cargos. On short ssRNA (≤814 nt), SV40 pentamers form 22 nm diameter capsids. On RNA too long to fit a T = 1 particle, pentamers forms strings of 22 nm particles and heterogeneous particles of 29-40 nm diameter. However, on dsDNA SV40 forms 50 nm particles composed of 72 pentamers. A 7.2-Å resolution cryo-EM image reconstruction of 22 nm particles shows that they are built of 12 pentamers arranged with T = 1 icosahedral symmetry. At 3-fold vertices, pentamers each contribute to a three-helix triangle. This geometry of interaction is not seen in crystal structures of T = 7 viruses and provides a structural basis for the smaller capsids. We propose that the heterogeneous particles are actually mosaics formed by combining different geometries of interaction from T = 1 capsids and virions. Assembly can be trapped in novel conformations because SV40 interpentamer contacts are relatively strong. The implication is that by virtue of their large catalog of interactions, SV40 pentamers have the ability to self-assemble on and conform to a broad range of shapes.
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Affiliation(s)
- Stanislav Kler
- Department
of Hematology, Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
| | - Joseph Che-Yen Wang
- Department
of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Mary Dhason
- Department
of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Ariella Oppenheim
- Department
of Hematology, Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
| | - Adam Zlotnick
- Department
of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana 47405, United States
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138
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Saribas AS, Mun S, Johnson J, El-Hajmoussa M, White MK, Safak M. Human polyoma JC virus minor capsid proteins, VP2 and VP3, enhance large T antigen binding to the origin of viral DNA replication: evidence for their involvement in regulation of the viral DNA replication. Virology 2013; 449:1-16. [PMID: 24418532 DOI: 10.1016/j.virol.2013.10.031] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2013] [Revised: 07/08/2013] [Accepted: 10/22/2013] [Indexed: 10/26/2022]
Abstract
JC virus (JCV) lytically infects the oligodendrocytes in the central nervous system in a subset of immunocompromized patients and causes the demyelinating disease, progressive multifocal leukoencephalopathy. JCV replicates and assembles into infectious virions in the nucleus. However, understanding the molecular mechanisms of its virion biogenesis remains elusive. In this report, we have attempted to shed more light on this process by investigating molecular interactions between large T antigen (LT-Ag), Hsp70 and minor capsid proteins, VP2/VP3. We demonstrated that Hsp70 interacts with VP2/VP3 and LT-Ag; and accumulates heavily in the nucleus of the infected cells. We also showed that VP2/VP3 associates with LT-Ag through their DNA binding domains resulting in enhancement in LT-Ag DNA binding to Ori and induction in viral DNA replication. Altogether, our results suggest that VP2/VP3 and Hsp70 actively participate in JCV DNA replication and may play critical roles in coupling of viral DNA replication to virion encapsidation.
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Affiliation(s)
- A Sami Saribas
- Department of Neuroscience, Laboratory of Molecular Neurovirology, MERB-757, Temple University School of Medicine, 3500 N. Broad Street, Philadelphia, PA 19140, United States
| | - Sarah Mun
- Department of Neuroscience, Laboratory of Molecular Neurovirology, MERB-757, Temple University School of Medicine, 3500 N. Broad Street, Philadelphia, PA 19140, United States
| | - Jaslyn Johnson
- Department of Neuroscience, Laboratory of Molecular Neurovirology, MERB-757, Temple University School of Medicine, 3500 N. Broad Street, Philadelphia, PA 19140, United States
| | - Mohammad El-Hajmoussa
- Department of Neuroscience, Laboratory of Molecular Neurovirology, MERB-757, Temple University School of Medicine, 3500 N. Broad Street, Philadelphia, PA 19140, United States
| | - Martyn K White
- Department of Neuroscience, Laboratory of Molecular Neurovirology, MERB-757, Temple University School of Medicine, 3500 N. Broad Street, Philadelphia, PA 19140, United States
| | - Mahmut Safak
- Department of Neuroscience, Laboratory of Molecular Neurovirology, MERB-757, Temple University School of Medicine, 3500 N. Broad Street, Philadelphia, PA 19140, United States.
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139
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Neu U, Khan ZM, Schuch B, Palma AS, Liu Y, Pawlita M, Feizi T, Stehle T. Structures of B-lymphotropic polyomavirus VP1 in complex with oligosaccharide ligands. PLoS Pathog 2013; 9:e1003714. [PMID: 24204265 PMCID: PMC3814675 DOI: 10.1371/journal.ppat.1003714] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Accepted: 09/03/2013] [Indexed: 12/04/2022] Open
Abstract
B-Lymphotropic Polyomavirus (LPyV) serves as a paradigm of virus receptor binding and tropism, and is the closest relative of the recently discovered Human Polyomavirus 9 (HPyV9). LPyV infection depends on sialic acid on host cells, but the molecular interactions underlying LPyV-receptor binding were unknown. We find by glycan array screening that LPyV specifically recognizes a linear carbohydrate motif that contains α2,3-linked sialic acid. High-resolution crystal structures of the LPyV capsid protein VP1 alone and in complex with the trisaccharide ligands 3′-sialyllactose and 3′-sialyl-N-acetyl-lactosamine (3SL and 3SLN, respectively) show essentially identical interactions. Most contacts are contributed by the sialic acid moiety, which is almost entirely buried in a narrow, preformed cleft at the outer surface of the capsid. The recessed nature of the binding site on VP1 and the nature of the observed glycan interactions differ from those of related polyomaviruses and most other sialic acid-binding viruses, which bind sialic acid in shallow, more exposed grooves. Despite their different modes for recognition, the sialic acid binding sites of LPyV and SV40 are half-conserved, hinting at an evolutionary strategy for diversification of binding sites. Our analysis provides a structural basis for the observed specificity of LPyV for linear glycan motifs terminating in α2,3-linked sialic acid, and links the different tropisms of known LPyV strains to the receptor binding site. It also serves as a useful template for understanding the ligand-binding properties and serological crossreactivity of HPyV9. Viruses must engage specific receptors on host cells in order to initiate infection. The type of receptor and its concentration on cells determine viral spread and tropism, but for many viruses, the receptor and the mode of recognition by the virus are not known. We have characterized the structural requirements for receptor binding of B-lymphotropic polyomavirus (LPyV). This virus was originally isolated from African Green Monkey lymph node cultures and attracted interest because of its narrow tropism for a human tumor cell line. LPyV is also the closest relative of the recently discovered Human Polyomavirus 9 (HPyV9). We screened the LPyV coat protein VP1 on an carbohydrate microarray and found that it specifically recognizes a linear sugar motif that terminates in α2,3-linked sialic acid. We then determined the structures LPyV VP1 bound to these carbohydrates. The protein has a preformed, deeply recessed binding site for sialic acid. The binding site differs in both architecture and mode of recognition from the binding sites of other viruses. LPyV only binds linear carbohydrates that are able to penetrate into the binding slot.
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Affiliation(s)
- Ursula Neu
- Interfaculty Institute of Biochemistry, University of Tuebingen, Tuebingen, Germany
| | - Zaigham Mahmood Khan
- Interfaculty Institute of Biochemistry, University of Tuebingen, Tuebingen, Germany
| | - Benjamin Schuch
- Interfaculty Institute of Biochemistry, University of Tuebingen, Tuebingen, Germany
| | - Angelina S. Palma
- Glycosciences Laboratory, Department of Medicine, Imperial College London, London, United Kingdom
| | - Yan Liu
- Glycosciences Laboratory, Department of Medicine, Imperial College London, London, United Kingdom
| | - Michael Pawlita
- Department of Genome Modificati and Carcinogenesis (F020), German Cancer Research Center, Heidelberg, Germany
| | - Ten Feizi
- Glycosciences Laboratory, Department of Medicine, Imperial College London, London, United Kingdom
| | - Thilo Stehle
- Interfaculty Institute of Biochemistry, University of Tuebingen, Tuebingen, Germany
- Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- * E-mail:
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140
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Neu U, Allen SAA, Blaum BS, Liu Y, Frank M, Palma AS, Ströh LJ, Feizi T, Peters T, Atwood WJ, Stehle T. A structure-guided mutation in the major capsid protein retargets BK polyomavirus. PLoS Pathog 2013; 9:e1003688. [PMID: 24130487 PMCID: PMC3795024 DOI: 10.1371/journal.ppat.1003688] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 08/21/2013] [Indexed: 11/19/2022] Open
Abstract
Viruses within a family often vary in their cellular tropism and pathogenicity. In many cases, these variations are due to viruses switching their specificity from one cell surface receptor to another. The structural requirements that underlie such receptor switching are not well understood especially for carbohydrate-binding viruses, as methods capable of structure-specificity studies are only relatively recently being developed for carbohydrates. We have characterized the receptor specificity, structure and infectivity of the human polyomavirus BKPyV, the causative agent of polyomavirus-associated nephropathy, and uncover a molecular switch for binding different carbohydrate receptors. We show that the b-series gangliosides GD3, GD2, GD1b and GT1b all can serve as receptors for BKPyV. The crystal structure of the BKPyV capsid protein VP1 in complex with GD3 reveals contacts with two sialic acid moieties in the receptor, providing a basis for the observed specificity. Comparison with the structure of simian virus 40 (SV40) VP1 bound to ganglioside GM1 identifies the amino acid at position 68 as a determinant of specificity. Mutation of this residue from lysine in BKPyV to serine in SV40 switches the receptor specificity of BKPyV from GD3 to GM1 both in vitro and in cell culture. Our findings highlight the plasticity of viral receptor binding sites and form a template to retarget viruses to different receptors and cell types. Viruses need to bind to receptors on host cells for viral entry and infection, and the type of receptor bound determines the range of hosts and tissues the virus can infect. Viruses within a family often vary in their tissue distribution and pathogenicity because changes in receptor specificity can produce a virus with different spread and infectivity. In fact, many transmissions between species are based on a virus acquiring binding capability for a new receptor. The structural changes that underlie such receptor switching are not well understood. We have analyzed the structural requirements for receptor binding and switching of the human BK polyomavirus (BKPyV), the causative agent of polyomavirus-associated nephropathy. We show that BKPyV uses specific gangliosides that all contain a common α2,8-disialic acid motif to infect cells, and have characterized the interaction in atomic detail. Our data explains the requirement for this disialic acid motif and in particular highlights a single amino acid that is central to determining specificity. Mutation of this residue switches the receptor specificity, enabling BKPyV to infect cells bearing a different class of gangliosides. Our findings highlight the plasticity of viral receptor binding sites and form a template to retarget viruses to different receptors and cell types.
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Affiliation(s)
- Ursula Neu
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Stacy-ann A. Allen
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island, United States of America
| | - Bärbel S. Blaum
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
- Department of Chemistry, University of Luebeck, Luebeck, Germany
| | - Yan Liu
- Glycosciences Laboratory, Faculty of Medicine, Imperial College London, London, United Kingdom
| | | | - Angelina S. Palma
- Glycosciences Laboratory, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Luisa J. Ströh
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Ten Feizi
- Glycosciences Laboratory, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Thomas Peters
- Department of Chemistry, University of Luebeck, Luebeck, Germany
| | - Walter J. Atwood
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island, United States of America
- * E-mail: (WJA); (TS)
| | - Thilo Stehle
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
- Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- * E-mail: (WJA); (TS)
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141
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Cysteine residues in the major capsid protein, Vp1, of the JC virus are important for protein stability and oligomer formation. PLoS One 2013; 8:e76668. [PMID: 24130786 PMCID: PMC3793911 DOI: 10.1371/journal.pone.0076668] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Accepted: 08/26/2013] [Indexed: 01/25/2023] Open
Abstract
The capsid of the human polyomavirus JC virus (JCV) consists of 72 pentameric capsomeres of a major structural protein, Vp1. The cysteine residues of the related Vp1 of SV40 are known to contribute to Vp1 folding, pentamer formation, pentamer-pentamer contacts, and capsid stabilization. In light of the presence of a slight structural difference between JCV Vp1 and SV40 counterpart, the way the former folds could be either different from or similar to the latter. We found a difference: an important contribution of Vp1 cysteines to the formation of infectious virions, unique in JCV and absent in SV40. Having introduced amino acid substitution at each of six cysteines (C42, C80, C97, C200, C247, and C260) in JCV Vp1, we found that, when expressed in HeLa cells, the Vp1 level was decreased in C80A and C247A mutants, and remained normal in the other mutants. Additionally, the C80A and C247A Vp1-expressing cell extracts did not show the hemagglutination activity characteristic of JCV particles. The C80A and C247A mutant Vp1s were found to be less stable than the wild-type Vp1 in HeLa cells. When produced in a reconstituted in vitro protein translation system, these two mutant proteins were stable, suggesting that some cellular factors were responsible for their degradation. As determined by their sucrose gradient sedimentation profiles, in vitro translated C247A Vp1 formed pentamers, but in vitro translated C80A Vp1 was entirely monomeric. When individually incorporated into the JCV genome, the C80A and C247A mutants, but not the other Vp1 cysteine residues mutants, interfered with JCV infectivity. Furthermore, the C80A, but not the C247A, mutation prevented the nuclear localization of Vp1 in JCV genome transfected cells. These findings suggest that C80 of JCV Vp1 is required for Vp1 stability and pentamer formation, and C247 is involved in capsid assembly in the nucleus.
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142
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Teunissen EA, de Raad M, Mastrobattista E. Production and biomedical applications of virus-like particles derived from polyomaviruses. J Control Release 2013; 172:305-321. [PMID: 23999392 DOI: 10.1016/j.jconrel.2013.08.026] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Revised: 08/18/2013] [Accepted: 08/20/2013] [Indexed: 10/26/2022]
Abstract
Virus-like particles (VLPs), aggregates of capsid proteins devoid of viral genetic material, show great promise in the fields of vaccine development and gene therapy. These particles spontaneously self-assemble after heterologous expression of viral structural proteins. This review will focus on the use of virus-like particles derived from polyomavirus capsid proteins. Since their first recombinant production 27 years ago these particles have been investigated for a myriad of biomedical applications. These virus-like particles are safe, easy to produce, can be loaded with a broad range of diverse cargoes and can be tailored for specific delivery or epitope presentation. We will highlight the structural characteristics of polyomavirus-derived VLPs and give an overview of their applications in diagnostics, vaccine development and gene delivery.
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Affiliation(s)
- Erik A Teunissen
- Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, University of Utrecht, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Markus de Raad
- Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, University of Utrecht, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Enrico Mastrobattista
- Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, University of Utrecht, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands.
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143
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Lagatie O, Tritsmans L, Stuyver LJ. The miRNA world of polyomaviruses. Virol J 2013; 10:268. [PMID: 23984639 PMCID: PMC3765807 DOI: 10.1186/1743-422x-10-268] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Accepted: 08/27/2013] [Indexed: 12/20/2022] Open
Abstract
Polyomaviruses are a family of non-enveloped DNA viruses infecting several species, including humans, primates, birds, rodents, bats, horse, cattle, raccoon and sea lion. They typically cause asymptomatic infection and establish latency but can be reactivated under certain conditions causing severe diseases. MicroRNAs (miRNAs) are small non-coding RNAs that play important roles in several cellular processes by binding to and inhibiting the translation of specific mRNA transcripts. In this review, we summarize the current knowledge of microRNAs involved in polyomavirus infection. We review in detail the different viral miRNAs that have been discovered and the role they play in controlling both host and viral protein expression. We also give an overview of the current understanding on how host miRNAs may function in controlling polyomavirus replication, immune evasion and pathogenesis.
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Affiliation(s)
- Ole Lagatie
- Janssen Diagnostics, Turnhoutseweg 30, Beerse 2340, Belgium.
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144
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Schowalter RM, Buck CB. The Merkel cell polyomavirus minor capsid protein. PLoS Pathog 2013; 9:e1003558. [PMID: 23990782 PMCID: PMC3749969 DOI: 10.1371/journal.ppat.1003558] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Accepted: 07/02/2013] [Indexed: 01/02/2023] Open
Abstract
The surface of polyomavirus virions is composed of pentameric knobs of the major capsid protein, VP1. In previously studied polyomavirus species, such as SV40, two interior capsid proteins, VP2 and VP3, emerge from the virion to play important roles during the infectious entry process. Translation of the VP3 protein initiates at a highly conserved Met-Ala-Leu motif within the VP2 open reading frame. Phylogenetic analyses indicate that Merkel cell polyomavirus (MCV or MCPyV) is a member of a divergent clade of polyomaviruses that lack the conserved VP3 N-terminal motif. Consistent with this observation, we show that VP3 is not detectable in MCV-infected cells, VP3 is not found in native MCV virions, and mutation of possible alternative VP3-initiating methionine codons did not significantly affect MCV infectivity in culture. In contrast, VP2 knockout resulted in a >100-fold decrease in native MCV infectivity, despite normal virion assembly, viral DNA packaging, and cell attachment. Although pseudovirus-based experiments confirmed that VP2 plays an essential role for infection of some cell lines, other cell lines were readily transduced by pseudovirions lacking VP2. In cell lines where VP2 was needed for efficient infectious entry, the presence of a conserved myristoyl modification on the N-terminus of VP2 was important for its function. The results show that a single minor capsid protein, VP2, facilitates a post-attachment stage of MCV infectious entry into some, but not all, cell types. Merkel cell polyomavirus (MCV or MCPyV) is a recently discovered member of the viral family Polyomaviridae. The virus plays a causal role in Merkel cell carcinoma, a highly lethal form of skin cancer. MCV encodes a major capsid protein, VP1, which forms the non-enveloped surface of the virion. Other polyomavirus species encode two minor capsid proteins, VP2 and VP3, which associate with the inner surface of the capsid and facilitate infectious entry. In this report we show that MCV does not have a VP3 minor capsid protein. Sequence analyses suggest that more than a quarter of known polyomavirus species share MCV's lack of a VP3 protein. In contrast to VP3, VP2-knockout MCV mutants displayed dramatically reduced infectivity. Consistent with native virion findings, MCV pseudovirions lacking VP2 or carrying mutations in the VP2 myristoylation motif displayed reduced infectivity on several cell lines. Puzzlingly, MCV pseudoviruses lacking VP2 successfully transduced other cell lines with high efficiency. Taken together, the data show that the lone MCV minor capsid protein, VP2, plays an important role during infectious entry into some cell types, but is dispensable for entry into other cell types.
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Affiliation(s)
- Rachel M. Schowalter
- Tumor Virus Molecular Biology Section, Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Christopher B. Buck
- Tumor Virus Molecular Biology Section, Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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145
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Enomoto T, Kawano M, Fukuda H, Sawada W, Inoue T, Haw KC, Kita Y, Sakamoto S, Yamaguchi Y, Imai T, Hatakeyama M, Saito S, Sandhu A, Matsui M, Aoki I, Handa H. Viral protein-coating of magnetic nanoparticles using simian virus 40 VP1. J Biotechnol 2013; 167:8-15. [DOI: 10.1016/j.jbiotec.2013.06.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Revised: 06/04/2013] [Accepted: 06/07/2013] [Indexed: 11/29/2022]
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146
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Abstract
Sialic acid linked to glycoproteins and gangliosides is used by many viruses as a receptor for cell entry. These viruses include important human and animal pathogens, such as influenza, parainfluenza, mumps, corona, noro, rota, and DNA tumor viruses. Attachment to sialic acid is mediated by receptor binding proteins that are constituents of viral envelopes or exposed at the surface of non-enveloped viruses. Some of these viruses are also equipped with a neuraminidase or a sialyl-O-acetyl-esterase. These receptor-destroying enzymes promote virus release from infected cells and neutralize sialic acid-containing soluble proteins interfering with cell surface binding of the virus. Variations in the receptor specificity are important determinants for host range, tissue tropism, pathogenicity, and transmissibility of these viruses.
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Affiliation(s)
| | - Philippe Delannoy
- Lille University of Science and Technology, Villeneuve d'Ascq Cedex, France
| | - Mark von Itzstein
- Institute for Glycomics, Griffith University, Southport, Queensland Australia
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147
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Gao D, Zhang ZP, Li F, Men D, Deng JY, Wei HP, Zhang XE, Cui ZQ. Quantum dot-induced viral capsid assembling in dissociation buffer. Int J Nanomedicine 2013; 8:2119-28. [PMID: 23776332 PMCID: PMC3681329 DOI: 10.2147/ijn.s44534] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Viruses encapsulating inorganic nanoparticles are a novel type of nanostructure with applications in biomedicine and biosensors. However, the encapsulation and assembly mechanisms of these hybridized virus-based nanoparticles (VNPs) are still unknown. In this article, it was found that quantum dots (QDs) can induce simian virus 40 (SV40) capsid assembly in dissociation buffer, where viral capsids should be disassembled. The analysis of the transmission electron microscope, dynamic light scattering, sucrose density gradient centrifugation, and cryo-electron microscopy single particle reconstruction experimental results showed that the SV40 major capsid protein 1 (VP1) can be assembled into ≈25 nm capsids in the dissociation buffer when QDs are present and that the QDs are encapsulated in the SV40 capsids. Moreover, it was determined that there is a strong affinity between QDs and the SV40 VP1 proteins (KD = 2.19E-10 M), which should play an important role in QD encapsulation in the SV40 viral capsids. This study provides a new understanding of the assembly mechanism of SV40 virus-based nanoparticles with QDs, which may help in the design and construction of other similar virus-based nanoparticles.
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Affiliation(s)
- Ding Gao
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
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148
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Heymann JB, Winkler DC, Yim YI, Eisenberg E, Greene LE, Steven AC. Clathrin-coated vesicles from brain have small payloads: a cryo-electron tomographic study. J Struct Biol 2013; 184:43-51. [PMID: 23688956 DOI: 10.1016/j.jsb.2013.05.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 04/25/2013] [Accepted: 05/09/2013] [Indexed: 02/02/2023]
Abstract
Clathrin coats, which stabilize membrane curvature during endocytosis and vesicular trafficking, form highly polymorphic fullerene lattices. We used cryo-electron tomography to visualize coated particles in isolates from bovine brain. The particles range from ∼66 to ∼134nm in diameter, and only 20% of them (all ⩾80nm) contain vesicles. The remaining 80% are clathrin "baskets", presumably artifactual assembly products. Polyhedral models were built for 54 distinct coat geometries. In true coated vesicles (CVs), most vesicles are offset to one side, leaving a crescent of interstitial space between the coat and the membrane for adaptor proteins and other components. The latter densities are fewer on the membrane-proximal side, which may represent the last part of the vesicle to bud off. A small number of densities - presumably cargo proteins - are associated with the interior surface of the vesicles. The clathrin coat, adaptor proteins, and vesicle membrane contribute almost all of the mass of a CV, with most cargoes accounting for only a few percent. The assembly of a CV therefore represents a massive biosynthetic effort to internalize a relatively diminutive payload. Such a high investment may be needed to overcome the resistance of membranes to high curvature.
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Affiliation(s)
- J Bernard Heymann
- Laboratory of Structural Biology Research, National Institute of Arthritis, Musculoskeletal and Skin Diseases, Bethesda, MD 20892, United States.
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149
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Moens U, Van Ghelue M, Song X, Ehlers B. Serological cross-reactivity between human polyomaviruses. Rev Med Virol 2013; 23:250-64. [DOI: 10.1002/rmv.1747] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Revised: 03/26/2013] [Accepted: 03/28/2013] [Indexed: 12/21/2022]
Affiliation(s)
- Ugo Moens
- University of Tromsø, Faculty of Health Sciences; Department of Medical Biology; Tromsø Norway
| | - Marijke Van Ghelue
- University Hospital of Northern-Norway; Department of Medical Genetics; Tromsø Norway
| | - Xiaobo Song
- University of Tromsø, Faculty of Health Sciences; Department of Medical Biology; Tromsø Norway
| | - Bernhard Ehlers
- Robert Koch Institute; Department of Infectious Diseases; Berlin Germany
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150
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Abstract
It has been known for many decades that cell surface, soluble-secreted, and extracellular matrix proteins are generally rich in disulfide bonds, but only more recently has the functional diversity of disulfide bonding in extracellular proteins been appreciated. In addition to the classic mechanisms by which disulfide bonds enhance protein thermodynamic stability, disulfides in certain configurations contribute particular mechanical properties to proteins that sense and respond to tensile forces. Disulfides may help warp protein folds for the evolution of new functions, or they may fasten aggregation-prone flaps of polypeptide to protein surfaces to prevent fibrilization or oligomerization. Disulfides can also be used to package and secure macromolecular cargo for intercellular transport. A series of case studies illustrating diverse biophysical roles of disulfide bonding are reviewed, with a focus on proteins functioning in the extracellular environment.
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Affiliation(s)
- Deborah Fass
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 76100, Israel.
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