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Liu M, Xu C, Zhou Y, Xue M, Jiang N, Li Y, Huang Z, Meng Y, Liu W, Kong X, Fan Y. Biochemical profiling of the protein encoded by grass carp reovirus genotype II. iScience 2024; 27:110502. [PMID: 39220409 PMCID: PMC11363571 DOI: 10.1016/j.isci.2024.110502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 04/21/2024] [Accepted: 07/10/2024] [Indexed: 09/04/2024] Open
Abstract
In this study, we obtained the whole genome sequence of GCRV-DY197 and investigated the localization, post-translational modifications, and host interactions of the 11 viral proteins encoded by GCRV-DY197 in grass carp ovary (GCO) cells. The whole genome sequence is 24,704 kb and contains 11 segments (S1-S11). Subcellular localization showed that the VP1, VP2, VP3, VP5, VP56, and VP35 proteins were localized in both cytoplasm and nucleus, whereas the NS79, VP4, VP41, VP6, and NS38 proteins were localized in the cytoplasm. The NS79 and NS38 proteins were phosphorylated, and the ubiquitination modification sites were identified in VP41 and NS38. An interaction network containing 9 viral proteins and 140 host proteins was also constructed. These results offer a theoretical basis for an in-depth understanding of the biochemical characteristics and pathogenic mechanism of GCRV-II.
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Affiliation(s)
- Man Liu
- Engineering Lab of Henan Province for Aquatic Animal Disease Control, College of Fisheries, Henan Normal University, Xinxiang 453000, China
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Chen Xu
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Yong Zhou
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Mingyang Xue
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Nan Jiang
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Yiqun Li
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Zhenyu Huang
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Yan Meng
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Wenzhi Liu
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Xianghui Kong
- Engineering Lab of Henan Province for Aquatic Animal Disease Control, College of Fisheries, Henan Normal University, Xinxiang 453000, China
| | - Yuding Fan
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
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2
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Welsh OL, Roth AN, Sutherland DM, Dermody TS. Sequence polymorphisms in the reovirus σ1 attachment protein modulate encapsidation efficiency and replication in mice. J Virol 2024; 98:e0030524. [PMID: 38771042 PMCID: PMC11237452 DOI: 10.1128/jvi.00305-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Accepted: 04/23/2024] [Indexed: 05/22/2024] Open
Abstract
Many functions of viral attachment proteins are established, but less is known about the biological importance of viral attachment protein encapsidation efficiency. The mammalian orthoreovirus (reovirus) σ1 attachment protein forms filamentous trimers that incorporate into pentamers of the λ2 capsid protein. Reovirus strains vary in the efficiency of σ1 encapsidation onto progeny virions, which influences viral stability during entry into cells and the efficacy of tumor cell lysis. While the role of σ1 encapsidation has been evaluated in studies using cultured cells, the contribution of attachment protein encapsidation efficiency to viral infection in animals is less clear. Polymorphisms in reovirus σ1 at residues 22 and 249 have been implicated in viral dissemination in mice and susceptibility to proteolysis in the murine intestine, respectively. To determine whether these residues contribute to σ1 encapsidation efficiency, we engineered σ1 mutant viruses with single- and double-residue substitutions at sites 22 and 249. We found that substitutions at these sites alter the encapsidation of σ1 and that reoviruses encapsidating higher amounts of σ1 bind cells more avidly and have a modest replication advantage in a cell-type-specific manner relative to low σ1-encapsidating reoviruses. Furthermore, we found that a high σ1-encapsidating reovirus replicates and disseminates more efficiently in mice relative to a low σ1-encapsidating reovirus. These findings provide evidence of a relationship between viral attachment protein encapsidation efficiency and viral replication in cell culture and animal hosts. IMPORTANCE Viral attachment proteins can serve multiple functions during viral replication, including attachment to host cells, cell entry and disassembly, and modulation of host immune responses. The relationship between viral attachment protein encapsidation efficiency and viral replication in cells and animals is poorly understood. We engineered and characterized a panel of reoviruses that differ in the capacity to encapsidate the σ1 attachment protein. We found that strains encapsidating σ1 with higher efficiency bind cells more avidly and replicate and spread more efficiently in mice relative to those encapsidating σ1 with lower efficiency. These results highlight a function for σ1 attachment protein capsid abundance in viral replication in cells and animals, which may inform future use of reovirus as an oncolytic therapeutic.
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Affiliation(s)
- Olivia L. Welsh
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Institute of Infection, Inflammation, and Immunity, UPMC Children’s Hospital of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Alexa N. Roth
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Institute of Infection, Inflammation, and Immunity, UPMC Children’s Hospital of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Danica M. Sutherland
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Institute of Infection, Inflammation, and Immunity, UPMC Children’s Hospital of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Terence S. Dermody
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Institute of Infection, Inflammation, and Immunity, UPMC Children’s Hospital of Pittsburgh, Pittsburgh, Pennsylvania, USA
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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3
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Shang P, Dos Santos Natividade R, Taylor GM, Ray A, Welsh OL, Fiske KL, Sutherland DM, Alsteens D, Dermody TS. NRP1 is a receptor for mammalian orthoreovirus engaged by distinct capsid subunits. Cell Host Microbe 2024; 32:980-995.e9. [PMID: 38729153 PMCID: PMC11176008 DOI: 10.1016/j.chom.2024.04.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 03/27/2024] [Accepted: 04/17/2024] [Indexed: 05/12/2024]
Abstract
Mammalian orthoreovirus (reovirus) is a nonenveloped virus that establishes primary infection in the intestine and disseminates to sites of secondary infection, including the CNS. Reovirus entry involves multiple engagement factors, but how the virus disseminates systemically and targets neurons remains unclear. In this study, we identified murine neuropilin 1 (mNRP1) as a receptor for reovirus. mNRP1 binds reovirus with nanomolar affinity using a unique mechanism of virus-receptor interaction, which is coordinated by multiple interactions between distinct reovirus capsid subunits and multiple NRP1 extracellular domains. By exchanging essential capsid protein-encoding gene segments, we determined that the multivalent interaction is mediated by outer-capsid protein σ3 and capsid turret protein λ2. Using capsid mutants incapable of binding NRP1, we found that NRP1 contributes to reovirus dissemination and neurovirulence in mice. Collectively, our results demonstrate that NRP1 is an entry receptor for reovirus and uncover mechanisms by which NRPs promote viral entry and pathogenesis.
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Affiliation(s)
- Pengcheng Shang
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Institute of Infection, Inflammation, and Immunity, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, USA
| | - Rita Dos Santos Natividade
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Gwen M Taylor
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Institute of Infection, Inflammation, and Immunity, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, USA
| | - Ankita Ray
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Olivia L Welsh
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Institute of Infection, Inflammation, and Immunity, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, USA
| | - Kay L Fiske
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Institute of Infection, Inflammation, and Immunity, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, USA
| | - Danica M Sutherland
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Institute of Infection, Inflammation, and Immunity, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, USA
| | - David Alsteens
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain, Louvain-la-Neuve, Belgium; WELBIO department, WEL Research Institute, Wavre, Belgium
| | - Terence S Dermody
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Institute of Infection, Inflammation, and Immunity, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, USA; Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
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4
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Li Z, Xia H, Rao G, Fu Y, Chong T, Tian K, Yuan Z, Cao S. Cryo-EM structures of Banna virus in multiple states reveal stepwise detachment of viral spikes. Nat Commun 2024; 15:2284. [PMID: 38480794 PMCID: PMC10937716 DOI: 10.1038/s41467-024-46624-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Accepted: 02/28/2024] [Indexed: 03/17/2024] Open
Abstract
Banna virus (BAV) is the prototype Seadornavirus, a class of reoviruses for which there has been little structural study. Here, we report atomic cryo-EM structures of three states of BAV virions-surrounded by 120 spikes (full virions), 60 spikes (partial virions), or no spikes (cores). BAV cores are double-layered particles similar to the cores of other non-turreted reoviruses, except for an additional protein component in the outer capsid shell, VP10. VP10 was identified to be a cementing protein that plays a pivotal role in the assembly of BAV virions by directly interacting with VP2 (inner capsid), VP8 (outer capsid), and VP4 (spike). Viral spikes (VP4/VP9 heterohexamers) are situated on top of VP10 molecules in full or partial virions. Asymmetrical electrostatic interactions between VP10 monomers and VP4 trimers are disrupted by high pH treatment, which is thus a simple way to produce BAV cores. Low pH treatment of BAV virions removes only the flexible receptor binding protein VP9 and triggers significant conformational changes in the membrane penetration protein VP4. BAV virions adopt distinct spatial organization of their surface proteins compared with other well-studied reoviruses, suggesting that BAV may have a unique mechanism of penetration of cellular endomembranes.
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Affiliation(s)
- Zhiqiang Li
- CAS Key Laboratory of Special Pathogens, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, 430071, PR China
- University of Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Han Xia
- CAS Key Laboratory of Special Pathogens, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, 430071, PR China
| | - Guibo Rao
- CAS Key Laboratory of Special Pathogens, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, 430071, PR China
| | - Yan Fu
- CAS Key Laboratory of Special Pathogens, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, 430071, PR China
| | - Tingting Chong
- CAS Key Laboratory of Special Pathogens, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, 430071, PR China
- University of Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Kexing Tian
- CAS Key Laboratory of Special Pathogens, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, 430071, PR China
- University of Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Zhiming Yuan
- CAS Key Laboratory of Special Pathogens, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, 430071, PR China.
| | - Sheng Cao
- CAS Key Laboratory of Special Pathogens, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, 430071, PR China.
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5
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Dhar D, Mehanovic S, Moss W, Miller CL. Sequences at gene segment termini inclusive of untranslated regions and partial open reading frames play a critical role in mammalian orthoreovirus S gene packaging. PLoS Pathog 2024; 20:e1012037. [PMID: 38394338 PMCID: PMC10917250 DOI: 10.1371/journal.ppat.1012037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 03/06/2024] [Accepted: 02/08/2024] [Indexed: 02/25/2024] Open
Abstract
Mammalian orthoreovirus (MRV) is a prototypic member of the Spinareoviridae family and has ten double-stranded RNA segments. One copy of each segment must be faithfully packaged into the mature virion, and prior literature suggests that nucleotides (nts) at the terminal ends of each gene likely facilitate their packaging. However, little is known about the precise packaging sequences required or how the packaging process is coordinated. Using a novel approach, we have determined that 200 nts at each terminus, inclusive of untranslated regions (UTR) and parts of the open reading frame (ORF), are sufficient for packaging S gene segments (S1-S4) individually and together into replicating virus. Further, we mapped the minimal sequences required for packaging the S1 gene segment into a replicating virus to 25 5' nts and 50 3' nts. The S1 UTRs, while not sufficient, were necessary for efficient packaging, as mutations of the 5' or 3' UTRs led to a complete loss of virus recovery. Using a second novel assay, we determined that 50 5' nts and 50 3' nts of S1 are sufficient to package a non-viral gene segment into MRV. The 5' and 3' termini of the S1 gene are predicted to form a panhandle structure and specific mutations within the stem of the predicted panhandle region led to a significant decrease in viral recovery. Additionally, mutation of six nts that are conserved across the three major serotypes of MRV that are predicted to form an unpaired loop in the S1 3' UTR, led to a complete loss of viral recovery. Overall, our data provide strong experimental proof that MRV packaging signals lie at the terminal ends of the S gene segments and offer support that the sequence requirements for efficient packaging of the S1 segment include a predicted panhandle structure and specific sequences within an unpaired loop in the 3' UTR.
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Affiliation(s)
- Debarpan Dhar
- Interdepartmental Microbiology Graduate Program, Iowa State University, Ames, Iowa, United States of America
- Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa, United States of America
| | - Samir Mehanovic
- Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa, United States of America
| | - Walter Moss
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa, United States of America
| | - Cathy L. Miller
- Interdepartmental Microbiology Graduate Program, Iowa State University, Ames, Iowa, United States of America
- Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa, United States of America
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6
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Abad AT, McNamara AJ, Danthi P. Proteasome activity is required for reovirus entry into cells. J Virol 2023; 97:e0134823. [PMID: 37830819 PMCID: PMC10617490 DOI: 10.1128/jvi.01348-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 09/04/2023] [Indexed: 10/14/2023] Open
Abstract
IMPORTANCE Due to their limited genetic capacity, viruses are reliant on multiple host systems to replicate successfully. Mammalian orthoreovirus (reovirus) is commonly used as a model system for understanding host-virus interactions. In this study, we identify that the proteasome system, which is critical for cellular protein turnover, affects reovirus entry. Inhibition of the proteasome using a chemical inhibitor blocks reovirus uncoating. Blocking these events reduces subsequent replication of the virus. This work identifies that additional host factors control reovirus entry.
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Affiliation(s)
- Andrew T. Abad
- Department of Biology, Indiana University, Bloomington, Indiana, USA
| | | | - Pranav Danthi
- Department of Biology, Indiana University, Bloomington, Indiana, USA
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7
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Stevens A, Cui Y, Shivakoti S, Zhou ZH. Asymmetric reconstruction of the aquareovirus core at near-atomic resolution and mechanism of transcription initiation. Protein Cell 2023; 14:544-548. [PMID: 36856784 PMCID: PMC10305738 DOI: 10.1093/procel/pwad002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/30/2022] [Indexed: 02/05/2023] Open
Affiliation(s)
- Alexander Stevens
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles (UCLA), 609 Charles E Young Dr E, Los Angeles, CA 90095, USA
- California NanoSystems Institute, UCLA, 570 Westwood Plaza Building 114 | Mail Code: 722710, Los Angeles, CA 90095, USA
- Department of Chemistry and Biochemistry, UCLA, 607 Charles E. Young Drive East | Box 951569, Los Angeles, CA 90095-1569, USA
| | - Yanxiang Cui
- California NanoSystems Institute, UCLA, 570 Westwood Plaza Building 114 | Mail Code: 722710, Los Angeles, CA 90095, USA
| | - Sakar Shivakoti
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles (UCLA), 609 Charles E Young Dr E, Los Angeles, CA 90095, USA
| | - Z Hong Zhou
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles (UCLA), 609 Charles E Young Dr E, Los Angeles, CA 90095, USA
- California NanoSystems Institute, UCLA, 570 Westwood Plaza Building 114 | Mail Code: 722710, Los Angeles, CA 90095, USA
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8
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Sutherland DM, Strebl M, Koehler M, Welsh OL, Yu X, Hu L, dos Santos Natividade R, Knowlton JJ, Taylor GM, Moreno RA, Wörz P, Lonergan ZR, Aravamudhan P, Guzman-Cardozo C, Kour S, Pandey UB, Alsteens D, Wang Z, Prasad BVV, Stehle T, Dermody TS. NgR1 binding to reovirus reveals an unusual bivalent interaction and a new viral attachment protein. Proc Natl Acad Sci U S A 2023; 120:e2219404120. [PMID: 37276413 PMCID: PMC10268256 DOI: 10.1073/pnas.2219404120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 04/19/2023] [Indexed: 06/07/2023] Open
Abstract
Nogo-66 receptor 1 (NgR1) binds a variety of structurally dissimilar ligands in the adult central nervous system to inhibit axon extension. Disruption of ligand binding to NgR1 and subsequent signaling can improve neuron outgrowth, making NgR1 an important therapeutic target for diverse neurological conditions such as spinal crush injuries and Alzheimer's disease. Human NgR1 serves as a receptor for mammalian orthoreovirus (reovirus), but the mechanism of virus-receptor engagement is unknown. To elucidate how NgR1 mediates cell binding and entry of reovirus, we defined the affinity of interaction between virus and receptor, determined the structure of the virus-receptor complex, and identified residues in the receptor required for virus binding and infection. These studies revealed that central NgR1 surfaces form a bridge between two copies of viral capsid protein σ3, establishing that σ3 serves as a receptor ligand for reovirus. This unusual binding interface produces high-avidity interactions between virus and receptor to prime early entry steps. These studies refine models of reovirus cell-attachment and highlight the evolution of viruses to engage multiple receptors using distinct capsid components.
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Affiliation(s)
- Danica M. Sutherland
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA15224
- Institute of Infection, Inflammation, and Immunity, University of Pittsburgh Medical Center Children’s Hospital of Pittsburgh, Pittsburgh, PA15224
| | - Michael Strebl
- Interfaculty Institute of Biochemistry, University of Tübingen, D-72076Tübingen, Germany
| | - Melanie Koehler
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain, 1348Louvain-la-Neuve, Belgium
| | - Olivia L. Welsh
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA15224
- Institute of Infection, Inflammation, and Immunity, University of Pittsburgh Medical Center Children’s Hospital of Pittsburgh, Pittsburgh, PA15224
| | - Xinzhe Yu
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX77030
| | - Liya Hu
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX77030
| | - Rita dos Santos Natividade
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain, 1348Louvain-la-Neuve, Belgium
| | - Jonathan J. Knowlton
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA15224
- Cryo-Electron Microscopy and Tomography Core, Baylor College of Medicine, Houston, TX77030
| | - Gwen M. Taylor
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA15224
- Institute of Infection, Inflammation, and Immunity, University of Pittsburgh Medical Center Children’s Hospital of Pittsburgh, Pittsburgh, PA15224
| | - Rodolfo A. Moreno
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX77030
| | - Patrick Wörz
- Interfaculty Institute of Biochemistry, University of Tübingen, D-72076Tübingen, Germany
| | - Zachery R. Lonergan
- Cryo-Electron Microscopy and Tomography Core, Baylor College of Medicine, Houston, TX77030
| | - Pavithra Aravamudhan
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA15224
- Institute of Infection, Inflammation, and Immunity, University of Pittsburgh Medical Center Children’s Hospital of Pittsburgh, Pittsburgh, PA15224
| | - Camila Guzman-Cardozo
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA15224
- Institute of Infection, Inflammation, and Immunity, University of Pittsburgh Medical Center Children’s Hospital of Pittsburgh, Pittsburgh, PA15224
| | - Sukhleen Kour
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA15224
| | - Udai Bhan Pandey
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA15224
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN37232
- Department of Human Genetics, University of Pittsburgh School of Public Health, Pittsburgh, PA15261
| | - David Alsteens
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain, 1348Louvain-la-Neuve, Belgium
- Children’s Neuroscience Institute, University of Pittsburgh Medical Center Children’s Hospital of Pittsburgh, Pittsburgh, PA15224
| | - Zhao Wang
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX77030
- Walloon Excellence in Life Sciences and Biotechnology, 1300Wavre, Belgium
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX77030
| | - B. V. Venkataram Prasad
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX77030
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX77030
| | - Thilo Stehle
- Interfaculty Institute of Biochemistry, University of Tübingen, D-72076Tübingen, Germany
| | - Terence S. Dermody
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA15224
- Institute of Infection, Inflammation, and Immunity, University of Pittsburgh Medical Center Children’s Hospital of Pittsburgh, Pittsburgh, PA15224
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA15219
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9
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Dhar D, Mehanovic S, Moss W, Miller CL. Sequences at gene segment termini inclusive of untranslated regions and partial open reading frames play a critical role in mammalian orthoreovirus S gene packaging. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.25.542362. [PMID: 37292944 PMCID: PMC10245979 DOI: 10.1101/2023.05.25.542362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Mammalian orthoreovirus (MRV) is a prototypic member of the Spinareoviridae family and has ten double-stranded RNA segments. One copy of each segment must be faithfully packaged into the mature virion, and prior literature suggests that nucleotides (nts) at the terminal ends of each gene likely facilitate their packaging. However, little is known about the precise packaging sequences required or how the packaging process is coordinated. Using a novel approach, we have determined that 200 nts at each terminus, inclusive of untranslated regions (UTR) and parts of the open reading frame (ORF), are sufficient for packaging each S gene segment (S1-S4) individually and together into replicating virus. Further, we mapped the minimal sequences required for packaging the S1 gene segment to 25 5' nts and 50 3' nts. The S1 UTRs alone are not sufficient, but are necessary for packaging, as mutations of the 5' or 3' UTRs led to a complete loss of virus recovery. Using a second novel assay, we determined that 50 5'nts and 50 3' nts of S1 are sufficient to package a non-viral gene segment into MRV. The 5' and 3' termini of the S1 gene are predicted to form a panhandle structure and specific mutations within the predicted stem of the panhandle region led to a significant decrease in viral recovery. Additionally, mutation of six nts that are conserved in the three major serotypes of MRV and are predicted to form an unpaired loop in the S1 3'UTR, led to a complete loss of viral recovery. Overall, our data provide strong experimental proof that MRV packaging signals lie at the terminal ends of the S gene segments and offer support that the sequence requirements for efficient packaging of the S1 segment include a predicted panhandle structure and specific sequences within an unpaired loop in the 3' UTR.
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10
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Hagan MF, Mohajerani F. Self-assembly coupled to liquid-liquid phase separation. PLoS Comput Biol 2023; 19:e1010652. [PMID: 37186597 PMCID: PMC10212142 DOI: 10.1371/journal.pcbi.1010652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 05/25/2023] [Accepted: 04/26/2023] [Indexed: 05/17/2023] Open
Abstract
Liquid condensate droplets with distinct compositions of proteins and nucleic acids are widespread in biological cells. While it is known that such droplets, or compartments, can regulate irreversible protein aggregation, their effect on reversible self-assembly remains largely unexplored. In this article, we use kinetic theory and solution thermodynamics to investigate the effect of liquid-liquid phase separation on the reversible self-assembly of structures with well-defined sizes and architectures. We find that, when assembling subunits preferentially partition into liquid compartments, robustness against kinetic traps and maximum achievable assembly rates can be significantly increased. In particular, both the range of solution conditions leading to productive assembly and the corresponding assembly rates can increase by orders of magnitude. We analyze the rate equation predictions using simple scaling estimates to identify effects of liquid-liquid phase separation as a function of relevant control parameters. These results may elucidate self-assembly processes that underlie normal cellular functions or pathogenesis, and suggest strategies for designing efficient bottom-up assembly for nanomaterials applications.
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Affiliation(s)
- Michael F. Hagan
- Martin A. Fisher School of Physics, Brandeis University, Waltham, Massachusetts, United States of America
| | - Farzaneh Mohajerani
- Martin A. Fisher School of Physics, Brandeis University, Waltham, Massachusetts, United States of America
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11
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Zhang Q, Gao Y, Baker ML, Liu S, Jia X, Xu H, He J, Kaelber JT, Weng S, Jiang W. The structure of a 12-segmented dsRNA reovirus: New insights into capsid stabilization and organization. PLoS Pathog 2023; 19:e1011341. [PMID: 37083840 PMCID: PMC10155992 DOI: 10.1371/journal.ppat.1011341] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 05/03/2023] [Accepted: 04/02/2023] [Indexed: 04/22/2023] Open
Abstract
Infecting a wide range of hosts, members of Reovirales (formerly Reoviridae) consist of a genome with different numbers of segmented double stranded RNAs (dsRNA) encapsulated by a proteinaceous shell and carry out genome replication and transcription inside the virion. Several cryo-electron microscopy (cryo-EM) structures of reoviruses with 9, 10 or 11 segmented dsRNA genomes have revealed insights into genome arrangement and transcription. However, the structure and genome arrangement of 12-segmented Reovirales members remain poorly understood. Using cryo-EM, we determined the structure of mud crab reovirus (MCRV), a 12-segmented dsRNA virus that is a putative member of Reovirales in the non-turreted Sedoreoviridae family, to near-atomic resolutions with icosahedral symmetry (3.1 Å) and without imposing icosahedral symmetry (3.4 Å). These structures revealed the organization of the major capsid proteins in two layers: an outer T = 13 layer consisting of VP12 trimers and unique VP11 clamps, and an inner T = 1 layer consisting of VP3 dimers. Additionally, ten RNA dependent RNA polymerases (RdRp) were well resolved just below the VP3 layer but were offset from the 5-fold axes and arranged with D5 symmetry, which has not previously been seen in other members of Reovirales. The N-termini of VP3 were shown to adopt four unique conformations; two of which anchor the RdRps, while the other two conformations are likely involved in genome organization and capsid stability. Taken together, these structures provide a new level of understanding for capsid stabilization and genome organization of segmented dsRNA viruses.
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Affiliation(s)
- Qinfen Zhang
- State key lab for biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Yuanzhu Gao
- State key lab for biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Matthew L Baker
- Department of Biochemistry and Molecular Biology, Structural Biology Imaging Center, McGovern Medical School at the University of Texas Health Science Center, Houston, Texas, United States of America
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Shanshan Liu
- State key lab for biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Xudong Jia
- State key lab for biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Haidong Xu
- State key lab for biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Jianguo He
- State key lab for biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Jason T Kaelber
- Institute for Quantitative Biomedicine, Rutgers, The State University of New Jersey, Piscataway, New Jersey, United States of America
| | - Shaoping Weng
- State key lab for biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Wen Jiang
- Markey Center for Structural Biology, Department of Biological Sciences, Purdue University, West Lafayette, Indiana, United States of America
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12
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Williamson LE, Bandyopadhyay A, Bailey K, Sirohi D, Klose T, Julander JG, Kuhn RJ, Crowe JE. Structural constraints link differences in neutralization potency of human anti-Eastern equine encephalitis virus monoclonal antibodies. Proc Natl Acad Sci U S A 2023; 120:e2213690120. [PMID: 36961925 PMCID: PMC10068833 DOI: 10.1073/pnas.2213690120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 02/10/2023] [Indexed: 03/26/2023] Open
Abstract
Selection and development of monoclonal antibody (mAb) therapeutics against pathogenic viruses depends on certain functional characteristics. Neutralization potency, or the half-maximal inhibitory concentration (IC50) values, is an important characteristic of candidate therapeutic antibodies. Structural insights into the bases of neutralization potency differences between antiviral neutralizing mAbs are lacking. In this report, we present cryo-electron microscopy (EM) reconstructions of three anti-Eastern equine encephalitis virus (EEEV) neutralizing human mAbs targeting overlapping epitopes on the E2 protein, with greater than 20-fold differences in their respective IC50 values. From our structural and biophysical analyses, we identify several constraints that contribute to the observed differences in the neutralization potencies. Cryo-EM reconstructions of EEEV in complex with these Fab fragments reveal structural constraints that dictate intravirion or intervirion cross-linking of glycoprotein spikes by their IgG counterparts as a mechanism of neutralization. Additionally, we describe critical features for the recognition of EEEV by these mAbs including the epitope-paratope interaction surface, occupancy, and kinetic differences in on-rate for binding to the E2 protein. Each constraint contributes to the extent of EEEV inhibition for blockade of virus entry, fusion, and/or egress. These findings provide structural and biophysical insights into the differences in mechanism and neutralization potencies of these antibodies, which help inform rational design principles for candidate vaccines and therapeutic antibodies for all icosahedral viruses.
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Affiliation(s)
- Lauren E. Williamson
- The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN37232
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University, Nashville, TN37232
| | - Abhishek Bandyopadhyay
- Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN47907
| | - Kevin Bailey
- Institute for Antiviral Research, Utah State University, Logan, UT84335
| | - Devika Sirohi
- Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN47907
| | - Thomas Klose
- Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN47907
| | | | - Richard J. Kuhn
- Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN47907
| | - James E. Crowe
- The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN37232
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University, Nashville, TN37232
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN37232
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13
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In situ structures of polymerase complex of mammalian reovirus illuminate RdRp activation and transcription regulation. Proc Natl Acad Sci U S A 2022; 119:e2203054119. [PMID: 36469786 PMCID: PMC9897473 DOI: 10.1073/pnas.2203054119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2022] Open
Abstract
Mammalian reovirus (reovirus) is a multilayered, turreted member of Reoviridae characterized by transcription of dsRNA genome within the innermost capsid shell. Here, we present high-resolution in situ structures of reovirus transcriptase complex in an intact double-layered virion, and in the uncoated single-layered core particles in the unloaded, reloaded, pre-elongation, and elongation states, respectively, obtained by cryo-electron microscopy and sub-particle reconstructions. At the template entry of RNA-dependent RNA polymerase (RdRp), the RNA-loading region gets flexible after uncoating resulting in the unloading of terminal genomic RNA and inactivity of transcription. However, upon adding transcriptional substrates, the RNA-loading region is recovered leading the RNAs loaded again. The priming loop in RdRp was found to play a critical role in regulating transcription, which hinders the elongation of transcript in virion and triggers the rearrangement of RdRp C-terminal domain (CTD) during elongation, resulting in splitting of template-transcript hybrid and opening of transcript exit. With the integration of these structures, a transcriptional model of reovirus with five states is proposed. Our structures illuminate the RdRp activation and regulation of the multilayered turreted reovirus.
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14
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Després GD, Ngo K, Lemay G. The μ2 and λ1 Proteins of Mammalian Reovirus Modulate Early Events Leading to Induction of the Interferon Signaling Network. Viruses 2022; 14:v14122638. [PMID: 36560642 PMCID: PMC9780918 DOI: 10.3390/v14122638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 11/21/2022] [Accepted: 11/22/2022] [Indexed: 11/29/2022] Open
Abstract
It has been previously shown that amino acid polymorphisms in reovirus proteins μ2 and λ1 are associated with differing levels of interferon induction. In the present study, viruses carrying these polymorphisms in either or both proteins, were further studied. The two viral determinants exert a synergistic effect on the control of β-interferon induction at the protein and mRNA level, with a concomitant increase in RIG-I. In contrast, levels of phospho-Stat1 and interferon-stimulated genes are increased in singly substituted viruses but with no further increase when both substitutions were present. This suggests that the viral determinants are acting during initial events of viral recognition. Accordingly, difference between viruses was reduced when infection was performed with partially uncoated virions (ISVPs) and transfection of RNA recovered from early-infected cells recapitulates the differences between viruses harboring the different polymorphisms. Altogether, the data are consistent with a redundant or complementary role of μ2 and λ1, affecting either early disassembly or the nature of the viral RNA in the incoming viral particle. Proteins involved in viral RNA synthesis are thus involved in this likely critical aspect of the ability of different reovirus variants to infect various cell types, and to discriminate between parental and transformed/cancer cells.
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15
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Jenni S, Horwitz JA, Bloyet LM, Whelan SPJ, Harrison SC. Visualizing molecular interactions that determine assembly of a bullet-shaped vesicular stomatitis virus particle. Nat Commun 2022; 13:4802. [PMID: 35970826 PMCID: PMC9378655 DOI: 10.1038/s41467-022-32223-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Accepted: 07/18/2022] [Indexed: 11/09/2022] Open
Abstract
Vesicular stomatitis virus (VSV) is a negative-strand RNA virus with a non-segmented genome, closely related to rabies virus. Both have characteristic bullet-like shapes. We report the structure of intact, infectious VSV particles determined by cryogenic electron microscopy. By compensating for polymorphism among viral particles with computational classification, we obtained a reconstruction of the shaft ("trunk") at 3.5 Å resolution, with lower resolution for the rounded tip. The ribonucleoprotein (RNP), genomic RNA complexed with nucleoprotein (N), curls into a dome-like structure with about eight gradually expanding turns before transitioning into the regular helical trunk. Two layers of matrix (M) protein link the RNP with the membrane. Radial inter-layer subunit contacts are fixed within single RNA-N-M1-M2 modules, but flexible lateral and axial interactions allow assembly of polymorphic virions. Together with published structures of recombinant N in various states, our results suggest a mechanism for membrane-coupled self-assembly of VSV and its relatives.
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Affiliation(s)
- Simon Jenni
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA.
| | - Joshua A Horwitz
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA
- Department of Microbiology, Harvard Medical School, Boston, MA, 02115, USA
- Molecular Pharmacology and Virology Group, PureTech Health LLC, Boston, MA, 02210, USA
| | - Louis-Marie Bloyet
- Department of Microbiology, Harvard Medical School, Boston, MA, 02115, USA
- Department of Molecular Microbiology, Washington University in St. Louis, St. Louis, MO, 63110, USA
| | - Sean P J Whelan
- Department of Microbiology, Harvard Medical School, Boston, MA, 02115, USA
- Department of Molecular Microbiology, Washington University in St. Louis, St. Louis, MO, 63110, USA
| | - Stephen C Harrison
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA.
- Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, 02115, USA.
- Laboratory of Molecular Medicine, Boston Children's Hospital, Boston, MA, 02115, USA.
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16
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Hryc CF, Baker ML. AlphaFold2 and CryoEM: Revisiting CryoEM modeling in near-atomic resolution density maps. iScience 2022; 25:104496. [PMID: 35733789 PMCID: PMC9207676 DOI: 10.1016/j.isci.2022.104496] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 04/07/2022] [Accepted: 05/24/2022] [Indexed: 11/27/2022] Open
Abstract
With the advent of new artificial intelligence and machine learning algorithms, predictive modeling can, in some cases, produce structures on par with experimental methods. The combination of predictive modeling and experimental structure determination by electron cryomicroscopy (cryoEM) offers a tantalizing approach for producing robust atomic models of macromolecular assemblies. Here, we apply AlphaFold2 to a set of community standard data sets and compare the results with the corresponding reference maps and models. Moreover, we present three unique case studies from previously determined cryoEM density maps of viruses. Our results show that AlphaFold2 can not only produce reasonably accurate models for analysis and additional hypotheses testing, but can also potentially yield incorrect structures if not properly validated with experimental data. Whereas we outline numerous shortcomings and potential pitfalls of predictive modeling, the obvious synergy between predictive modeling and cryoEM will undoubtedly result in new computational modeling tools.
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Affiliation(s)
- Corey F. Hryc
- Department of Biochemistry and Molecular Biology, Structural Biology Imaging Center, McGovern Medical School at The University of Texas Health Science Center at Houston, 6431 Fannin Street, Houston, TX 77030, USA
| | - Matthew L. Baker
- Department of Biochemistry and Molecular Biology, Structural Biology Imaging Center, McGovern Medical School at The University of Texas Health Science Center at Houston, 6431 Fannin Street, Houston, TX 77030, USA
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17
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Boudreault S, Durand M, Martineau CA, Perreault JP, Lemay G, Bisaillon M. Reovirus μ2 protein modulates host cell alternative splicing by reducing protein levels of U5 snRNP core components. Nucleic Acids Res 2022; 50:5263-5281. [PMID: 35489070 PMCID: PMC9122528 DOI: 10.1093/nar/gkac272] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 03/25/2022] [Accepted: 04/26/2022] [Indexed: 11/13/2022] Open
Abstract
Mammalian orthoreovirus (MRV) is a double-stranded RNA virus from the Reoviridae family presenting a promising activity as an oncolytic virus. Recent studies have underlined MRV’s ability to alter cellular alternative splicing (AS) during infection, with a limited understanding of the mechanisms at play. In this study, we investigated how MRV modulates AS. Using a combination of cell biology and reverse genetics experiments, we demonstrated that the M1 gene segment, encoding the μ2 protein, is the primary determinant of MRV’s ability to alter AS, and that the amino acid at position 208 in μ2 is critical to induce these changes. Moreover, we showed that the expression of μ2 by itself is sufficient to trigger AS changes, and its ability to enter the nucleus is not required for all these changes. Moreover, we identified core components of the U5 snRNP (i.e. EFTUD2, PRPF8, and SNRNP200) as interactors of μ2 that are required for MRV modulation of AS. Finally, these U5 snRNP components are reduced at the protein level by both MRV infection and μ2 expression. Our findings identify the reduction of U5 snRNP components levels as a new mechanism by which viruses alter cellular AS.
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Affiliation(s)
- Simon Boudreault
- Département de biochimie et de génomique fonctionnelle, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, Québec J1E 4K8, Canada
| | - Mathieu Durand
- Plateforme de RNomique, Université de Sherbrooke, Sherbrooke, Québec J1E 4K8, Canada
| | - Carole-Anne Martineau
- Département de biochimie et de génomique fonctionnelle, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, Québec J1E 4K8, Canada
| | - Jean-Pierre Perreault
- Département de biochimie et de génomique fonctionnelle, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, Québec J1E 4K8, Canada
| | - Guy Lemay
- Département de microbiologie, infectiologie et immunologie, Faculté de médecine, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Martin Bisaillon
- Département de biochimie et de génomique fonctionnelle, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, Québec J1E 4K8, Canada
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18
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Abstract
Bluetongue virus (BTV), a member of Orbivirus genus, is transmitted by biting midges (gnats, Culicoides sp) and is one of the most widespread animal pathogens, causing serious outbreaks in domestic animals, particularly in sheep, with high economic impact. The non-enveloped BTV particle is a double-capsid structure of seven proteins and a genome of ten double-stranded RNA segments. Although the outermost spike-like VP2 acts as the attachment protein during BTV entry, no specific host receptor has been identified for BTV. Recent high-resolution cryo-electron (cryoEM) structures and biological data have suggested that VP2 may interact with sialic acids (SAs). To confirm this, we have generated protein-based nanoparticles displaying multivalent VP2 and used them to probe glycan arrays. The data show that VP2 binds α2,3-linked SA with high affinity but also binds α2,6-linked SA. Further, Maackia Amurensis Lectin II (MAL II) and Sambucus Nigra Lectin (SNA), which specifically bind α2,3-linked and α2,6-linked SAs respectively, inhibited BTV infection and virus growth in susceptible sheep cells while SNA alone inhibited virus growth in Culicoides-derived cells. A combination of hydrogen deuterium exchange mass spectrometry and site-directed mutagenesis allowed the identification of the specific SA binding residues of VP2. This study provides direct evidence that sialic acids act as key receptor for BTV and that the outer capsid protein VP2 specifically binds SA during BTV entry in both mammalian and insect cells. Importance To date no receptor has been assigned for non-enveloped bluetongue virus. To determine if the outermost spike-like VP2 protein is responsible for host cell attachment via interaction with sialic acids, we first generated a protein-based VP2-nanoparticle, for the multivalent presentation of recombinant VP2 protein. Using nanoparticles-displaying VP2 to probe a glycan array, we identified that VP2 binds both α2,3-linked and α2,6-linked sialic acids. Lectin inhibitors targeting both linkages of sialic acids showed strong inhibition to BTV infection and progeny virus production in mammalian cells, however the inhibition was only seen with the lectin targeting α2,6-linked sialic acid in insect vector cells. In addition, we identified the VP2 sialic acid binding sites in the exposed tip domain. Our data provides direct evidence that sialic acids act as key receptors for BTV attachment and entry in to both mammalian and insect cells.
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