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Shalamova L, Barth P, Pickin MJ, Kouti K, Ott B, Humpert K, Janssen S, Lorenzo G, Brun A, Goesmann A, Hain T, Hartmann RK, Rossbach O, Weber F. Nucleocapsids of the Rift Valley fever virus ambisense S segment contain an exposed RNA element in the center that overlaps with the intergenic region. Nat Commun 2024; 15:7602. [PMID: 39217162 PMCID: PMC11365940 DOI: 10.1038/s41467-024-52058-2] [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: 10/16/2023] [Accepted: 08/21/2024] [Indexed: 09/04/2024] Open
Abstract
Rift Valley fever virus (RVFV) is a mosquito-borne zoonotic pathogen. Its RNA genome consists of two negative-sense segments (L and M) with one gene each, and one ambisense segment (S) with two opposing genes separated by the noncoding "intergenic region" (IGR). These vRNAs and the complementary cRNAs are encapsidated by nucleoprotein (N). Using iCLIP2 (individual-nucleotide resolution UV crosslinking and immunoprecipitation) to map all N-vRNA and N-cRNA interactions, we detect N coverage along the L and M segments. However, the S segment vRNA and cRNA each contain approximately 100 non-encapsidated nucleotides stretching from the IGR into the 5'-adjacent reading frame. These exposed regions are RNase-sensitive and predicted to form stem-loop structures with the mRNA transcription termination motif positioned near the top. Moreover, optimal S segment transcription and replication requires the entire exposed region rather than only the IGR. Thus, the RVFV S segment contains a central, non-encapsidated RNA region with a functional role.
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Affiliation(s)
- Lyudmila Shalamova
- Institute for Virology, FB10-Veterinary Medicine, Justus-Liebig University, Giessen, Germany
| | - Patrick Barth
- Bioinformatics & Systems Biology, Justus-Liebig University, Giessen, Germany
- Cell Biology and Plant Biochemistry, University of Regensburg, Regensburg, Germany
| | - Matthew J Pickin
- Institute for Virology, FB10-Veterinary Medicine, Justus-Liebig University, Giessen, Germany
| | - Kiriaki Kouti
- Institute for Virology, FB10-Veterinary Medicine, Justus-Liebig University, Giessen, Germany
| | - Benjamin Ott
- Institute for Medical Microbiology, FB11-Medicine, Justus-Liebig University, Giessen, Germany
| | - Katharina Humpert
- Institute for Medical Microbiology, FB11-Medicine, Justus-Liebig University, Giessen, Germany
- Institute of Molecular Oncology, Genomics Core Facility, Philipps-University, Marburg, Germany
| | - Stefan Janssen
- Algorithmic Bioinformatics, Justus-Liebig University, Giessen, Germany
| | - Gema Lorenzo
- Centro de Investigación en Sanidad Animal (CISA-INIA/CSIC), Valdeolmos, Madrid, Spain
| | - Alejandro Brun
- Centro de Investigación en Sanidad Animal (CISA-INIA/CSIC), Valdeolmos, Madrid, Spain
| | - Alexander Goesmann
- Bioinformatics & Systems Biology, Justus-Liebig University, Giessen, Germany
| | - Torsten Hain
- Institute for Medical Microbiology, FB11-Medicine, Justus-Liebig University, Giessen, Germany
| | - Roland K Hartmann
- Institute of Pharmaceutical Chemistry, Philipps-University Marburg, Marburg, Germany
| | - Oliver Rossbach
- Institute for Biochemistry, FB 08-Biology and Chemistry, Justus-Liebig University, Giessen, Germany
| | - Friedemann Weber
- Institute for Virology, FB10-Veterinary Medicine, Justus-Liebig University, Giessen, Germany.
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2
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Hover S, Barr JN, Fontana J. Insights into the structure of RNPs from segmented negative-sense RNA viruses. Structure 2024; 32:1027-1028. [PMID: 39121836 DOI: 10.1016/j.str.2024.07.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2024] [Revised: 07/10/2024] [Accepted: 07/10/2024] [Indexed: 08/12/2024]
Abstract
The genome of segmented negative-sense single-stranded RNA viruses, such as influenza virus and bunyaviruses, is coated by viral nucleoproteins (NPs), forming a ribonucleoprotein (RNP). In this issue of Structure, Dick et al.1 expand our knowledge on the RNPs of these viruses by solving the structures of Thogoto virus NP and RNP.
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Affiliation(s)
- Samantha Hover
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK; Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK.
| | - John N Barr
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK; Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK.
| | - Juan Fontana
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK; Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK.
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3
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Sabsay KR, te Velthuis AJW. Negative and ambisense RNA virus ribonucleocapsids: more than protective armor. Microbiol Mol Biol Rev 2023; 87:e0008223. [PMID: 37750733 PMCID: PMC10732063 DOI: 10.1128/mmbr.00082-23] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/27/2023] Open
Abstract
SUMMARYNegative and ambisense RNA viruses are the causative agents of important human diseases such as influenza, measles, Lassa fever, and Ebola hemorrhagic fever. The viral genome of these RNA viruses consists of one or more single-stranded RNA molecules that are encapsidated by viral nucleocapsid proteins to form a ribonucleoprotein complex (RNP). This RNP acts as protection, as a scaffold for RNA folding, and as the context for viral replication and transcription by a viral RNA polymerase. However, the roles of the viral nucleoproteins extend beyond these functions during the viral infection cycle. Recent advances in structural biology techniques and analysis methods have provided new insights into the formation, function, dynamics, and evolution of negative sense virus nucleocapsid proteins, as well as the role that they play in host innate immune responses against viral infection. In this review, we discuss the various roles of nucleocapsid proteins, both in the context of RNPs and in RNA-free states, as well as the open questions that remain.
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Affiliation(s)
- Kimberly R. Sabsay
- Lewis Thomas Laboratory, Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, USA
| | - Aartjan J. W. te Velthuis
- Lewis Thomas Laboratory, Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
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4
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Chenavier F, Estrozi LF, Teulon JM, Zarkadas E, Freslon LL, Pellequer JL, Ruigrok RW, Schoehn G, Ballandras-Colas A, Crépin T. Cryo-EM structure of influenza helical nucleocapsid reveals NP-NP and NP-RNA interactions as a model for the genome encapsidation. SCIENCE ADVANCES 2023; 9:eadj9974. [PMID: 38100595 PMCID: PMC10848707 DOI: 10.1126/sciadv.adj9974] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 11/16/2023] [Indexed: 12/17/2023]
Abstract
Influenza virus genome encapsidation is essential for the formation of a helical viral ribonucleoprotein (vRNP) complex composed of nucleoproteins (NP), the trimeric polymerase, and the viral genome. Although low-resolution vRNP structures are available, it remains unclear how the viral RNA is encapsidated and how NPs assemble into the helical filament specific of influenza vRNPs. In this study, we established a biological tool, the RNP-like particles assembled from recombinant influenza A virus NP and synthetic RNA, and we present the first subnanometric cryo-electron microscopy structure of the helical NP-RNA complex (8.7 to 5.3 Å). The helical RNP-like structure reveals a parallel double-stranded conformation, allowing the visualization of NP-NP and NP-RNA interactions. The RNA, located at the interface of neighboring NP protomers, interacts with conserved residues previously described as essential for the NP-RNA interaction. The NP undergoes conformational changes to enable RNA binding and helix formation. Together, our findings provide relevant insights for understanding the mechanism for influenza genome encapsidation.
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Affiliation(s)
| | | | | | | | | | | | | | - Guy Schoehn
- Univ. Grenoble Alpes, CNRS, CEA, IBS, F-38000, Grenoble, France
| | | | - Thibaut Crépin
- Univ. Grenoble Alpes, CNRS, CEA, IBS, F-38000, Grenoble, France
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5
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Yvon M, German TL, Ullman DE, Dasgupta R, Parker MH, Ben-Mahmoud S, Verdin E, Gognalons P, Ancelin A, Laï Kee Him J, Girard J, Vernerey MS, Fernandez E, Filloux D, Roumagnac P, Bron P, Michalakis Y, Blanc S. The genome of a bunyavirus cannot be defined at the level of the viral particle but only at the scale of the viral population. Proc Natl Acad Sci U S A 2023; 120:e2309412120. [PMID: 37983500 PMCID: PMC10691328 DOI: 10.1073/pnas.2309412120] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Accepted: 10/21/2023] [Indexed: 11/22/2023] Open
Abstract
Bunyaviruses are enveloped negative or ambisense single-stranded RNA viruses with a genome divided into several segments. The canonical view depicts each viral particle packaging one copy of each genomic segment in one polarity named the viral strand. Several opposing observations revealed nonequal ratios of the segments, uneven number of segments per virion, and even packaging of viral complementary strands. Unfortunately, these observations result from studies often addressing other questions, on distinct viral species, and not using accurate quantitative methods. Hence, what RNA segments and strands are packaged as the genome of any bunyavirus remains largely ambiguous. We addressed this issue by first investigating the virion size distribution and RNA content in populations of the tomato spotted wilt virus (TSWV) using microscopy and tomography. These revealed heterogeneity in viral particle volume and amount of RNA content, with a surprising lack of correlation between the two. Then, the ratios of all genomic segments and strands were established using RNA sequencing and qRT-PCR. Within virions, both plus and minus strands (but no mRNA) are packaged for each of the three L, M, and S segments, in reproducible nonequimolar proportions determined by those in total cell extracts. These results show that virions differ in their genomic content but together build up a highly reproducible genetic composition of the viral population. This resembles the genome formula described for multipartite viruses, with which some species of the order Bunyavirales may share some aspects of the way of life, particularly emerging properties at a supravirion scale.
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Affiliation(s)
- Michel Yvon
- PHIM, Univ Montpellier, INRAE, CIRAD, IRD, Institut Agro, Montpellier34398, France
| | - Thomas L. German
- Department of Entomology, University of Wisconsin, Wisconsin53706, Madison
| | - Diane E. Ullman
- Department of Entomology and Nematology, University of California, California95616, Davis
| | - Ranjit Dasgupta
- Department of Entomology, University of Wisconsin, Wisconsin53706, Madison
| | - Maxwell H. Parker
- Department of Entomology, University of Wisconsin, Wisconsin53706, Madison
| | - Sulley Ben-Mahmoud
- Department of Entomology and Nematology, University of California, California95616, Davis
| | - Eric Verdin
- Pathologie végétale, INRAE, Avignon84143, France
| | | | - Aurélie Ancelin
- CBS, Univ Montpellier, CNRS, INSERM, Montpellier34090, France
| | | | - Justine Girard
- CBS, Univ Montpellier, CNRS, INSERM, Montpellier34090, France
| | | | - Emmanuel Fernandez
- PHIM, Univ Montpellier, INRAE, CIRAD, IRD, Institut Agro, Montpellier34398, France
| | - Denis Filloux
- PHIM, Univ Montpellier, INRAE, CIRAD, IRD, Institut Agro, Montpellier34398, France
| | - Philippe Roumagnac
- PHIM, Univ Montpellier, INRAE, CIRAD, IRD, Institut Agro, Montpellier34398, France
| | - Patrick Bron
- CBS, Univ Montpellier, CNRS, INSERM, Montpellier34090, France
| | | | - Stéphane Blanc
- PHIM, Univ Montpellier, INRAE, CIRAD, IRD, Institut Agro, Montpellier34398, France
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6
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Orba Y, Abu YE, Chambaro HM, Lundu T, Muleya W, Eshita Y, Qiu Y, Harima H, Kajihara M, Mori-Kajihara A, Matsuno K, Sasaki M, Hall WW, Hang'ombe BM, Sawa H. Expanding diversity of bunyaviruses identified in mosquitoes. Sci Rep 2023; 13:18165. [PMID: 37875565 PMCID: PMC10598057 DOI: 10.1038/s41598-023-45443-2] [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: 06/28/2023] [Accepted: 10/19/2023] [Indexed: 10/26/2023] Open
Abstract
Mosquitoes interact with various organisms in the environment, and female mosquitoes in particular serve as vectors that directly transmit a number of microorganisms to humans and animals by blood-sucking. Comprehensive analysis of mosquito-borne viruses has led to the understanding of the existence of diverse viral species and to the identification of zoonotic arboviruses responsible for significant outbreaks and epidemics. In the present study on mosquito-borne bunyaviruses we employed a broad-spectrum RT-PCR approach and identified eighteen different additional species in the Phenuiviridae family and also a number of related but unclassified bunyaviruses in mosquitoes collected in Zambia. The entire RNA genome segments of the newly identified viruses were further analyzed by RNA sequencing with a ribonuclease R (RNase R) treatment to reduce host-derived RNAs and enrich viral RNAs, taking advantage of the dsRNA panhandle structure of the bunyavirus genome. All three or four genome segments were identified in eight bunyavirus species. Furthermore, L segments of three different novel viruses related to the Leishbunyaviridae were found in mosquitoes together with genes from the suspected host, the Crithidia parasite. In summary, our virus detection approach using a combination of broad-spectrum RT-PCR and RNA sequencing analysis with a simple virus enrichment method allowed the discovery of novel bunyaviruses. The diversity of bunyaviruses is still expanding and studies on this will allow a better understanding of the ecology of hematophagous mosquitoes.
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Affiliation(s)
- Yasuko Orba
- Division of Molecular Pathobiology, International Institute for Zoonosis Control, Hokkaido University, N20, W10, Kita-ku, Sapporo, 001-0020, Japan.
- International Collaboration Unit, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Japan.
- Institute for Vaccine Research and Development, Hokkaido University, Sapporo, Japan.
- One Health Research Center, Hokkaido University, Sapporo, Japan.
| | - Yusuf Eshimutu Abu
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Zambia, P.O. Box 32379, 10101, Lusaka, Zambia
| | - Herman M Chambaro
- Division of Molecular Pathobiology, International Institute for Zoonosis Control, Hokkaido University, N20, W10, Kita-ku, Sapporo, 001-0020, Japan
- Virology Unit, Central Veterinary Research Institute, Lusaka, Zambia
| | - Tapiwa Lundu
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Zambia, P.O. Box 32379, 10101, Lusaka, Zambia
| | - Walter Muleya
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Zambia, P.O. Box 32379, 10101, Lusaka, Zambia
| | - Yuki Eshita
- Division of Collaboration and Education, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Japan
| | - Yongjin Qiu
- Division of International Research Promotion, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Japan
| | - Hayato Harima
- Division of International Research Promotion, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Japan
| | - Masahiro Kajihara
- Division of International Research Promotion, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Japan
| | - Akina Mori-Kajihara
- Division of Global Epidemiology, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Japan
| | - Keita Matsuno
- International Collaboration Unit, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Japan
- Institute for Vaccine Research and Development, Hokkaido University, Sapporo, Japan
- One Health Research Center, Hokkaido University, Sapporo, Japan
- Division of Risk Analysis and Management, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Japan
| | - Michihito Sasaki
- Division of Molecular Pathobiology, International Institute for Zoonosis Control, Hokkaido University, N20, W10, Kita-ku, Sapporo, 001-0020, Japan
- Institute for Vaccine Research and Development, Hokkaido University, Sapporo, Japan
| | - William W Hall
- International Collaboration Unit, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Japan
- National Virus Reference Laboratory, University College Dublin, Belfield, Dublin, 4, Ireland
- Global Virus Network, Baltimore, MD, USA
| | - Bernard M Hang'ombe
- Department of Para-Clinical Studies, School of Veterinary Medicine, University of Zambia, Lusaka, Zambia
- Africa Centre of Excellence for Infectious Diseases of Humans and Animals, Lusaka, Zambia
| | - Hirofumi Sawa
- International Collaboration Unit, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Japan.
- Institute for Vaccine Research and Development, Hokkaido University, Sapporo, Japan.
- One Health Research Center, Hokkaido University, Sapporo, Japan.
- National Virus Reference Laboratory, University College Dublin, Belfield, Dublin, 4, Ireland.
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7
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Hover S, Charlton FW, Hellert J, Swanson JJ, Mankouri J, Barr JN, Fontana J. Organisation of the orthobunyavirus tripodal spike and the structural changes induced by low pH and K + during entry. Nat Commun 2023; 14:5885. [PMID: 37735161 PMCID: PMC10514341 DOI: 10.1038/s41467-023-41205-w] [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: 09/16/2022] [Accepted: 08/26/2023] [Indexed: 09/23/2023] Open
Abstract
Following endocytosis, enveloped viruses employ the changing environment of maturing endosomes as cues to promote endosomal escape, a process often mediated by viral glycoproteins. We previously showed that both high [K+] and low pH promote entry of Bunyamwera virus (BUNV), the prototypical bunyavirus. Here, we use sub-tomogram averaging and AlphaFold, to generate a pseudo-atomic model of the whole BUNV glycoprotein envelope. We unambiguously locate the Gc fusion domain and its chaperone Gn within the floor domain of the spike. Furthermore, viral incubation at low pH and high [K+], reminiscent of endocytic conditions, results in a dramatic rearrangement of the BUNV envelope. Structural and biochemical assays indicate that pH 6.3/K+ in the absence of a target membrane elicits a fusion-capable triggered intermediate state of BUNV GPs; but the same conditions induce fusion when target membranes are present. Taken together, we provide mechanistic understanding of the requirements for bunyavirus entry.
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Affiliation(s)
- Samantha Hover
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, Leeds, United Kingdom
- Astbury Centre for Structural and Molecular Biology, University of Leeds, LS2 9JT, Leeds, United Kingdom
| | - Frank W Charlton
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, Leeds, United Kingdom
- Astbury Centre for Structural and Molecular Biology, University of Leeds, LS2 9JT, Leeds, United Kingdom
| | - Jan Hellert
- Centre for Structural Systems Biology, Leibniz-Institut für Virologie (LIV), Notkestraße 85, 22607, Hamburg, Germany
| | - Jessica J Swanson
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, Leeds, United Kingdom
- Astbury Centre for Structural and Molecular Biology, University of Leeds, LS2 9JT, Leeds, United Kingdom
| | - Jamel Mankouri
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, Leeds, United Kingdom.
- Astbury Centre for Structural and Molecular Biology, University of Leeds, LS2 9JT, Leeds, United Kingdom.
| | - John N Barr
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, Leeds, United Kingdom.
- Astbury Centre for Structural and Molecular Biology, University of Leeds, LS2 9JT, Leeds, United Kingdom.
| | - Juan Fontana
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, Leeds, United Kingdom.
- Astbury Centre for Structural and Molecular Biology, University of Leeds, LS2 9JT, Leeds, United Kingdom.
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8
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Izhaki-Tavor LS, Yechezkel IG, Alter J, Dessau M. RNA Encapsulation Mode and Evolutionary Insights from the Crystal Structure of Emaravirus Nucleoprotein. Microbiol Spectr 2023; 11:e0501822. [PMID: 37039649 PMCID: PMC10269810 DOI: 10.1128/spectrum.05018-22] [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: 12/07/2022] [Accepted: 02/27/2023] [Indexed: 04/12/2023] Open
Abstract
Enveloped RNA viruses are rare among plant viruses. Fimoviridae is a newly founded family of plant viruses within the Bunyavirales order that inflicts diverse crop losses worldwide. The fig mosaic virus (FMV), the representative member of the Fimoviridae family, was shown to be a causative agent for the fig mosaic disease. Like all bunyaviruses, FMV has a segmented, negative-sense, single-stranded RNA (ssRNA) genome that is encapsulated by the viral nucleoprotein (N). Here, we present high-resolution crystal structures of FMV N in its RNA-free and RNA-bound forms, revealing a "paper fortune teller" structural transition between the two states. The tightly packed tetramer of FNV N is similar to the structures of other N proteins of different members of the Bunyavirales order. In its RNA-bound form, the tetramer reorganizes to adopt a more open state that allows the accommodation of the RNA. Despite the low sequence similarity to N proteins of animal-infecting bunyaviruses, there is a striking structural resemblance between FMV N and nucleoproteins from members of the Peribunyaviridae, an animal-infecting family of viruses. This structural homology implies that enveloped plant viruses and animal-infecting viruses might have a common ancestor from which they diverged. IMPORTANCE Most insect-born viruses circulate within the Animalia kingdom, whereas plant-infecting RNA viruses are cross-kingdom pathogens. Many plant-infecting viruses cause devastating crop damage that leads to food security endangerment. The evolutionary crossroads of interkingdom circulation and infection are poorly understood. Thus, we took the structural approach to understand the similarities and differences between interkingdom-infecting viruses and viruses that circulate within one kingdom of life. Using our structures of FMV N in its free form and in complex with a single-stranded RNA (ssRNA), we dissected the mechanism by which FMV N binds to the RNA and revealed the conformational changes associated with the binding. The resemblance of our structure to N proteins from members of the Peribunyaviridae family and their recently published ribonucleoprotein (RNP) pseudoatomic resolution assembly model suggests that the FMV genome is similarly encapsulated. Thus, our finding unveils yet another bridge by which plant- and animal-infecting viruses are interconnected.
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Affiliation(s)
- Lee S. Izhaki-Tavor
- Azrieli Faculty of Medicine in the Galilee, Bar-Ilan University, Safed, Israel
| | - Itai G. Yechezkel
- Azrieli Faculty of Medicine in the Galilee, Bar-Ilan University, Safed, Israel
| | - Joel Alter
- Azrieli Faculty of Medicine in the Galilee, Bar-Ilan University, Safed, Israel
| | - Moshe Dessau
- Azrieli Faculty of Medicine in the Galilee, Bar-Ilan University, Safed, Israel
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9
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Modrego A, Carlero D, Arranz R, Martín-Benito J. CryoEM of Viral Ribonucleoproteins and Nucleocapsids of Single-Stranded RNA Viruses. Viruses 2023; 15:v15030653. [PMID: 36992363 PMCID: PMC10053253 DOI: 10.3390/v15030653] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 02/24/2023] [Accepted: 02/25/2023] [Indexed: 03/05/2023] Open
Abstract
Single-stranded RNA viruses (ssRNAv) are characterized by their biological diversity and great adaptability to different hosts; traits which make them a major threat to human health due to their potential to cause zoonotic outbreaks. A detailed understanding of the mechanisms involved in viral proliferation is essential to address the challenges posed by these pathogens. Key to these processes are ribonucleoproteins (RNPs), the genome-containing RNA-protein complexes whose function is to carry out viral transcription and replication. Structural determination of RNPs can provide crucial information on the molecular mechanisms of these processes, paving the way for the development of new, more effective strategies to control and prevent the spread of ssRNAv diseases. In this scenario, cryogenic electron microscopy (cryoEM), relying on the technical and methodological revolution it has undergone in recent years, can provide invaluable help in elucidating how these macromolecular complexes are organized, packaged within the virion, or the functional implications of these structures. In this review, we summarize some of the most prominent achievements by cryoEM in the study of RNP and nucleocapsid structures in lipid-enveloped ssRNAv.
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Affiliation(s)
- Andrea Modrego
- Departamento de Estructura de Macromoléculas, Centro Nacional de Biotecnología Consejo Superior de Investigaciones Científicas (CNB-CSIC), 28049 Madrid, Spain
| | - Diego Carlero
- Departamento de Estructura de Macromoléculas, Centro Nacional de Biotecnología Consejo Superior de Investigaciones Científicas (CNB-CSIC), 28049 Madrid, Spain
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid (UAM), 28049 Madrid, Spain
| | - Rocío Arranz
- Departamento de Estructura de Macromoléculas, Centro Nacional de Biotecnología Consejo Superior de Investigaciones Científicas (CNB-CSIC), 28049 Madrid, Spain
- Correspondence: (R.A.); (J.M.-B.)
| | - Jaime Martín-Benito
- Departamento de Estructura de Macromoléculas, Centro Nacional de Biotecnología Consejo Superior de Investigaciones Científicas (CNB-CSIC), 28049 Madrid, Spain
- Correspondence: (R.A.); (J.M.-B.)
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10
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Hellert J, Aebischer A, Haouz A, Guardado-Calvo P, Reiche S, Beer M, Rey FA. Structure, function, and evolution of the Orthobunyavirus membrane fusion glycoprotein. Cell Rep 2023; 42:112142. [PMID: 36827185 DOI: 10.1016/j.celrep.2023.112142] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Revised: 12/29/2022] [Accepted: 02/07/2023] [Indexed: 02/24/2023] Open
Abstract
La Crosse virus, responsible for pediatric encephalitis in the United States, and Schmallenberg virus, a highly teratogenic veterinary virus in Europe, belong to the large Orthobunyavirus genus of zoonotic arthropod-borne pathogens distributed worldwide. Viruses in this under-studied genus cause CNS infections or fever with debilitating arthralgia/myalgia syndromes, with no effective treatment. The main surface antigen, glycoprotein Gc (∼1,000 residues), has a variable N-terminal half (GcS) targeted by the patients' antibody response and a conserved C-terminal moiety (GcF) responsible for membrane fusion during cell entry. Here, we report the X-ray structure of post-fusion La Crosse and Schmallenberg virus GcF, revealing the molecular determinants for hairpin formation and trimerization required to drive membrane fusion. We further experimentally confirm the role of residues in the fusion loops and in a vestigial endoplasmic reticulum (ER) translocation sequence at the GcS-GcF junction. The resulting knowledge provides essential molecular underpinnings for future development of potential therapeutic treatments and vaccines.
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Affiliation(s)
- Jan Hellert
- Structural Virology Unit, Institut Pasteur - Université Paris-Cité, CNRS UMR 3569, 25-28 rue du Dr. Roux, 75015 Paris, France; Centre for Structural Systems Biology (CSSB), Leibniz-Institut für Virologie (LIV), Notkestraße 85, 22607 Hamburg, Germany
| | - Andrea Aebischer
- Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Südufer 10, 17493 Greifswald, Germany; Department of Experimental Animal Facilities and Biorisk Management, Friedrich-Loeffler-Institut, Südufer 10, 17493 Greifswald, Germany
| | - Ahmed Haouz
- Crystallography Platform C2RT, Institut Pasteur, CNRS UMR 3528, 25-28 rue du Dr. Roux, 75015 Paris, France
| | - Pablo Guardado-Calvo
- Structural Virology Unit, Institut Pasteur - Université Paris-Cité, CNRS UMR 3569, 25-28 rue du Dr. Roux, 75015 Paris, France
| | - Sven Reiche
- Department of Experimental Animal Facilities and Biorisk Management, Friedrich-Loeffler-Institut, Südufer 10, 17493 Greifswald, Germany
| | - Martin Beer
- Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Südufer 10, 17493 Greifswald, Germany.
| | - Félix A Rey
- Structural Virology Unit, Institut Pasteur - Université Paris-Cité, CNRS UMR 3569, 25-28 rue du Dr. Roux, 75015 Paris, France.
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Malet H, Williams HM, Cusack S, Rosenthal M. The mechanism of genome replication and transcription in bunyaviruses. PLoS Pathog 2023; 19:e1011060. [PMID: 36634042 PMCID: PMC9836281 DOI: 10.1371/journal.ppat.1011060] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Bunyaviruses are negative sense, single-strand RNA viruses that infect a wide range of vertebrate, invertebrate and plant hosts. WHO lists three bunyavirus diseases as priority diseases requiring urgent development of medical countermeasures highlighting their high epidemic potential. While the viral large (L) protein containing the RNA-dependent RNA polymerase is a key enzyme in the viral replication cycle and therefore a suitable drug target, our knowledge on the structure and activities of this multifunctional protein has, until recently, been very limited. However, in the last few years, facilitated by the technical advances in the field of cryogenic electron microscopy, many structures of bunyavirus L proteins have been solved. These structures significantly enhance our mechanistic understanding of bunyavirus genome replication and transcription processes and highlight differences and commonalities between the L proteins of different bunyavirus families. Here, we provide a review of our current understanding of genome replication and transcription in bunyaviruses with a focus on the viral L protein. Further, we compare within bunyaviruses and with the related influenza virus polymerase complex and highlight open questions.
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Affiliation(s)
- Hélène Malet
- University Grenoble Alpes, CNRS, CEA, IBS, Grenoble, France
- Institut Universitaire de France (IUF), Paris, France
| | - Harry M. Williams
- Bernhard Nocht Institute for Tropical Medicine (BNITM), Hamburg, Germany
- Centre for Structural Systems Biology, Hamburg, Germany
| | | | - Maria Rosenthal
- Bernhard Nocht Institute for Tropical Medicine (BNITM), Hamburg, Germany
- Centre for Structural Systems Biology, Hamburg, Germany
- Fraunhofer Institute for Translational Medicine and Pharmacology (ITMP), Discovery Research ScreeningPort, Hamburg, Germany
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