1
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Tsukamoto Y, Igarashi M, Kato H. Targeting cap1 RNA methyltransferases as an antiviral strategy. Cell Chem Biol 2024; 31:86-99. [PMID: 38091983 DOI: 10.1016/j.chembiol.2023.11.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 10/30/2023] [Accepted: 11/20/2023] [Indexed: 01/21/2024]
Abstract
Methylation is one of the critical modifications that regulates numerous biological processes. Guanine capping and methylation at the 7th position (m7G) have been shown to mature mRNA for increased RNA stability and translational efficiency. The m7G capped cap0 RNA remains immature and requires additional methylation at the first nucleotide (N1-2'-O-Me), designated as cap1, to achieve full maturation. This cap1 RNA with N1-2'-O-Me prevents its recognition by innate immune sensors as non-self. Viruses have also evolved various strategies to produce self-like capped RNAs with the N1-2'-O-Me that potentially evades the antiviral response and establishes an efficient replication. In this review, we focus on the importance of the presence of N1-2'-O-Me in viral RNAs and discuss the potential for drug development by targeting host and viral N1-2'-O-methyltransferases.
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Affiliation(s)
- Yuta Tsukamoto
- Institute of Cardiovascular Immunology, Medical Faculty, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - Manabu Igarashi
- Division of Global Epidemiology, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Japan; International Collaboration Unit, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Hiroki Kato
- Institute of Cardiovascular Immunology, Medical Faculty, University Hospital Bonn, University of Bonn, Bonn, Germany.
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2
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Tajima S, Kataoka M, Takamatsu Y, Ebihara H, Lim CK. Mutations in the 3' non-coding region of a no-known vector flavivirus Yokose virus increased its replication ability in mosquito C6/36 cells. Virology 2024; 589:109928. [PMID: 37949004 DOI: 10.1016/j.virol.2023.109928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 10/25/2023] [Accepted: 10/30/2023] [Indexed: 11/12/2023]
Abstract
Yokose virus (YOKV) is a bat-associated no-known vector flavivirus group member. We investigated the replication ability of YOKV in mosquito-derived C6/36 cells. YOKV grew in C6/36 cells, but its kinetics of YOKV was markedly slower than those of other mosquito-borne flaviviruses. Transmission electron microscopy indicated an extremely small number of viral particles in YOKV-infected C6/36 cells. Mosquito-borne Japanese encephalitis virus prM-E-bearing chimeric YOKV failed to propagate efficiently in C6/36 cells. We isolated C6/36-adapted YOKV and identified nucleotide mutations in the adapted YOKV. Mutations detected in the 3' non-coding region of the adapted YOKV were critical for the enhanced proliferation ability of the virus. Moreover, the growth of the original and adapted YOKV in C6/36 cells was remarkably increased by shifting the culture temperature from 28 to 36 °C. Thus, our results demonstrate the potential of YOKV to propagate in mosquito cells and support its classification as a mosquito-borne flavivirus.
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Affiliation(s)
- Shigeru Tajima
- Department of Virology 1, National Institute of Infectious Diseases, Toyama 1-23-1, Shinjuku, Tokyo, 162-8640, Japan.
| | - Michiyo Kataoka
- Department of Pathology, National Institute of Infectious Diseases, Toyama 1-23-1, Shinjuku, Tokyo, 162-8640, Japan
| | - Yuki Takamatsu
- Department of Virology, Institute of Tropical Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki, Nagasaki, 852-8523, Japan
| | - Hideki Ebihara
- Department of Virology 1, National Institute of Infectious Diseases, Toyama 1-23-1, Shinjuku, Tokyo, 162-8640, Japan
| | - Chang-Kweng Lim
- Department of Virology 1, National Institute of Infectious Diseases, Toyama 1-23-1, Shinjuku, Tokyo, 162-8640, Japan
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3
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Chen H, Lin S, Yang F, Chen Z, Guo L, Yang J, Lin X, Wang L, Duan Y, Wen A, Zhang X, Dai Y, Yin K, Yuan X, Yu C, He Y, He B, Cao Y, Dong H, Li J, Zhao Q, Liu Q, Lu G. Structural and functional basis of low-affinity SAM/SAH-binding in the conserved MTase of the multi-segmented Alongshan virus distantly related to canonical unsegmented flaviviruses. PLoS Pathog 2023; 19:e1011694. [PMID: 37831643 PMCID: PMC10575543 DOI: 10.1371/journal.ppat.1011694] [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: 03/10/2023] [Accepted: 09/18/2023] [Indexed: 10/15/2023] Open
Abstract
Alongshan virus (ALSV), a newly discovered member of unclassified Flaviviridae family, is able to infect humans. ALSV has a multi-segmented genome organization and is evolutionarily distant from canonical mono-segmented flaviviruses. The virus-encoded methyltransferase (MTase) plays an important role in viral replication. Here we show that ALSV MTase readily binds S-adenosyl-L-methionine (SAM) and S-adenosyl-L-homocysteine (SAH) but exhibits significantly lower affinities than canonical flaviviral MTases. Structures of ALSV MTase in the free and SAM/SAH-bound forms reveal that the viral enzyme possesses a unique loop-element lining side-wall of the SAM/SAH-binding pocket. While the equivalent loop in flaviviral MTases half-covers SAM/SAH, contributing multiple hydrogen-bond interactions; the pocket-lining loop of ALSV MTase is of short-length and high-flexibility, devoid of any physical contacts with SAM/SAH. Subsequent mutagenesis data further corroborate such structural difference affecting SAM/SAH-binding. Finally, we also report the structure of ALSV MTase bound with sinefungin, an SAM-analogue MTase inhibitor. These data have delineated the basis for the low-affinity interaction between ALSV MTase and SAM/SAH and should inform on antiviral drug design.
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Affiliation(s)
- Hua Chen
- Department of Emergency Medicine, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
- Department of Wound Repair and Rehabilitation Medicine, State Key Laboratory of Trauma, Burns and Combined Injury, Daping Hospital, Army Medical University, Chongqing, China
| | - Sheng Lin
- Department of Emergency Medicine, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Fanli Yang
- Department of Emergency Medicine, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Zimin Chen
- Department of Emergency Medicine, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Liyan Guo
- Department of Emergency Medicine, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Jing Yang
- Department of Emergency Medicine, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Xi Lin
- Department of Emergency Medicine, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Lingling Wang
- Department of Emergency Medicine, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Yanping Duan
- Department of Emergency Medicine, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Ao Wen
- Department of Emergency Medicine, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Xindan Zhang
- Department of Emergency Medicine, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Yushan Dai
- Department of Emergency Medicine, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Keqing Yin
- Department of Emergency Medicine, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Xin Yuan
- Department of Emergency Medicine, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Chongzhang Yu
- Department of Emergency Medicine, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Yarong He
- Department of Emergency Medicine, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Bin He
- Department of Emergency Medicine, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Yu Cao
- Department of Emergency Medicine, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
- Disaster Medicine Center, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Haohao Dong
- State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Jian Li
- School of Basic Medical Sciences, Chengdu University, Chengdu, Sichuan, China
| | - Qi Zhao
- College of Food and Biological Engineering, Chengdu University, Chengdu, Sichuan, China
| | - Quan Liu
- Center of Infectious diseases and Pathogen Biology, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, The First Hospital of Jilin University, State Key Laboratory of Zoonotic Diseases, Changchun, Jilin, China
| | - Guangwen Lu
- Department of Emergency Medicine, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
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4
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Ferrero DS, Albentosa-González L, Mas A, Verdaguer N. Structure and function of the NS5 methyltransferase domain from Usutu virus. Antiviral Res 2022; 208:105460. [DOI: 10.1016/j.antiviral.2022.105460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 10/24/2022] [Accepted: 10/31/2022] [Indexed: 11/09/2022]
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5
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Abstract
The positive-sense flavivirus RNA genome bears a cap 1 structure essential for RNA stability and viral protein translation, and the formation of cap 1 requires the virally encoded nonstructural protein NS5 harboring guanylyltransferase (GTase), cap guanine N7 methyltransferase (N7 MTase), and 5'-nucleotide ribose 2'-O MTase activities in its single-domain MTase module. Despite numerous MTase-containing structures reported, the structural evidence for a critical GMP-enzyme intermediate formation and RNA repositioning when transitioning among different reactions is missing. Here, we report 10 high-resolution MTase crystal structures of Omsk hemorrhagic fever virus (OHFV), a representative high-consequence tick-borne flavivirus, capturing previously unidentified GMP-arginine adduct structures and a rarely observed capped RNA conformation. These structures help us thread capping events in the canonical model with a structure-based hypothesis involving the flipping of the 5' nucleotide, while the observation of an m7GMP-arginine adduct is compatible with an alternate capping model that decouples the N7 and 2'-O methylation steps. IMPORTANCE The methyltransferase (MTase) domain of flavivirus NS5 is unique in harboring guanylyltransferase (GTase), N7 MTase, and 2'-O MTase activities, playing a central role in viral RNA capping. However, the detailed mechanisms of the multistep capping process remain elusive. Here, we report 10 crystal structures of a flavivirus MTase to help understand the guanylyl transfer from GTP to the GTase itself and the transition between guanylyl transfer and methylation steps. In particular, a previously unobserved GMP-arginine covalent intermediate was captured multiple times in MTase crystal soaking trials with GTP present in the soaking solution, supporting its role in bridging the guanylyl transfer from GTP to the GTase and subsequent transfer to the 5'-diphosphate RNA.
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6
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Zhao R, Wang M, Cao J, Shen J, Zhou X, Wang D, Cao J. Flavivirus: From Structure to Therapeutics Development. Life (Basel) 2021; 11:life11070615. [PMID: 34202239 PMCID: PMC8303334 DOI: 10.3390/life11070615] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 06/16/2021] [Accepted: 06/22/2021] [Indexed: 12/25/2022] Open
Abstract
Flaviviruses are still a hidden threat to global human safety, as we are reminded by recent reports of dengue virus infections in Singapore and African-lineage-like Zika virus infections in Brazil. Therapeutic drugs or vaccines for flavivirus infections are in urgent need but are not well developed. The Flaviviridae family comprises a large group of enveloped viruses with a single-strand RNA genome of positive polarity. The genome of flavivirus encodes ten proteins, and each of them plays a different and important role in viral infection. In this review, we briefly summarized the major information of flavivirus and further introduced some strategies for the design and development of vaccines and anti-flavivirus compound drugs based on the structure of the viral proteins. There is no doubt that in the past few years, studies of antiviral drugs have achieved solid progress based on better understanding of the flavivirus biology. However, currently, there are no fully effective antiviral drugs or vaccines for most flaviviruses. We hope that this review may provide useful information for future development of anti-flavivirus drugs and vaccines.
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Affiliation(s)
- Rong Zhao
- Key Laboratory of Cellular Physiology, Ministry of Education, Shanxi Medical University, Taiyuan 030001, China; (R.Z.); (M.W.); (J.C.); (J.S.)
- Department of Physiology, Shanxi Medical University, Taiyuan 030001, China
| | - Meiyue Wang
- Key Laboratory of Cellular Physiology, Ministry of Education, Shanxi Medical University, Taiyuan 030001, China; (R.Z.); (M.W.); (J.C.); (J.S.)
- Department of Physiology, Shanxi Medical University, Taiyuan 030001, China
| | - Jing Cao
- Key Laboratory of Cellular Physiology, Ministry of Education, Shanxi Medical University, Taiyuan 030001, China; (R.Z.); (M.W.); (J.C.); (J.S.)
- Department of Physiology, Shanxi Medical University, Taiyuan 030001, China
| | - Jing Shen
- Key Laboratory of Cellular Physiology, Ministry of Education, Shanxi Medical University, Taiyuan 030001, China; (R.Z.); (M.W.); (J.C.); (J.S.)
- Department of Physiology, Shanxi Medical University, Taiyuan 030001, China
| | - Xin Zhou
- Department of Medical Imaging, Shanxi Medical University, Taiyuan 030001, China;
| | - Deping Wang
- Key Laboratory of Cellular Physiology, Ministry of Education, Shanxi Medical University, Taiyuan 030001, China; (R.Z.); (M.W.); (J.C.); (J.S.)
- Department of Physiology, Shanxi Medical University, Taiyuan 030001, China
- Correspondence: (D.W.); (J.C.)
| | - Jimin Cao
- Key Laboratory of Cellular Physiology, Ministry of Education, Shanxi Medical University, Taiyuan 030001, China; (R.Z.); (M.W.); (J.C.); (J.S.)
- Department of Physiology, Shanxi Medical University, Taiyuan 030001, China
- Correspondence: (D.W.); (J.C.)
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7
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Abstract
Most viruses in the genus Flavivirus are horizontally transmitted between hematophagous arthropods and vertebrate hosts, but some are maintained in arthropod- or vertebrate-restricted transmission cycles. Flaviviruses maintained by vertebrate-only transmission are commonly referred to as no known vector (NKV) flaviviruses. Fourteen species and two subtypes of NKV flaviviruses are recognized by the International Committee on Taxonomy of Viruses (ICTV), and Tamana bat virus potentially belongs to this group. NKV flaviviruses have been isolated in nature almost exclusively from bats and rodents; exceptions are the two isolates of Dakar bat virus recovered from febrile humans and the recent isolations of Sokoluk virus from field-collected ticks, which raises questions as to whether it should remain classified as an NKV flavivirus. There is evidence to suggest that two other NKV flaviviruses, Entebbe bat virus and Yokose virus, may also infect arthropods in nature. The best characterized bat- and rodent-associated NKV flaviviruses are Rio Bravo and Modoc viruses, respectively, but both have received limited research attention compared to many of their arthropod-infecting counterparts. Herein, we provide a comprehensive review of NKV flaviviruses, placing a particular emphasis on their classification, host range, geographic distribution, replication kinetics, pathogenesis, transmissibility and molecular biology.
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8
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Duan W, Song H, Wang H, Chai Y, Su C, Qi J, Shi Y, Gao GF. The crystal structure of Zika virus NS5 reveals conserved drug targets. EMBO J 2017; 36:919-933. [PMID: 28254839 DOI: 10.15252/embj.201696241] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Revised: 01/16/2017] [Accepted: 02/02/2017] [Indexed: 12/31/2022] Open
Abstract
Zika virus (ZIKV) has emerged as major health concern, as ZIKV infection has been shown to be associated with microcephaly, severe neurological disease and possibly male sterility. As the largest protein component within the ZIKV replication complex, NS5 plays key roles in the life cycle and survival of the virus through its N-terminal methyltransferase (MTase) and C-terminal RNA-dependent RNA polymerase (RdRp) domains. Here, we present the crystal structures of ZIKV NS5 MTase in complex with an RNA cap analogue (m7GpppA) and the free NS5 RdRp. We have identified the conserved features of ZIKV NS5 MTase and RdRp structures that could lead to development of current antiviral inhibitors being used against flaviviruses, including dengue virus and West Nile virus, to treat ZIKV infection. These results should inform and accelerate the structure-based design of antiviral compounds against ZIKV.
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Affiliation(s)
- Wenqian Duan
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
| | - Hao Song
- Research Network of Immunity and Health (RNIH), Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, China
| | - Haiyuan Wang
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,College of Animal Sciences and Technology, Guangxi University, Nanning, China
| | - Yan Chai
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Chao Su
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Jianxun Qi
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Yi Shi
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China .,Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China.,Research Network of Immunity and Health (RNIH), Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, China.,Center for Influenza Research and Early-warning (CASCIRE), Chinese Academy of Sciences, Beijing, China.,Shenzhen Key Laboratory of Pathogen and Immunity, Shenzhen Third People's Hospital, Shenzhen, China
| | - George F Gao
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China .,Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China.,Research Network of Immunity and Health (RNIH), Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, China.,Center for Influenza Research and Early-warning (CASCIRE), Chinese Academy of Sciences, Beijing, China.,Shenzhen Key Laboratory of Pathogen and Immunity, Shenzhen Third People's Hospital, Shenzhen, China.,National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention (China CDC), Beijing, China
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9
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da Fonseca NJ, Lima Afonso MQ, Pedersolli NG, de Oliveira LC, Andrade DS, Bleicher L. Sequence, structure and function relationships in flaviviruses as assessed by evolutive aspects of its conserved non-structural protein domains. Biochem Biophys Res Commun 2017; 492:565-571. [PMID: 28087275 DOI: 10.1016/j.bbrc.2017.01.041] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 01/09/2017] [Indexed: 10/20/2022]
Abstract
Flaviviruses are responsible for serious diseases such as dengue, yellow fever, and zika fever. Their genomes encode a polyprotein which, after cleavage, results in three structural and seven non-structural proteins. Homologous proteins can be studied by conservation and coevolution analysis as detected in multiple sequence alignments, usually reporting positions which are strictly necessary for the structure and/or function of all members in a protein family or which are involved in a specific sub-class feature requiring the coevolution of residue sets. This study provides a complete conservation and coevolution analysis on all flaviviruses non-structural proteins, with results mapped on all well-annotated available sequences. A literature review on the residues found in the analysis enabled us to compile available information on their roles and distribution among different flaviviruses. Also, we provide the mapping of conserved and coevolved residues for all sequences currently in SwissProt as a supplementary material, so that particularities in different viruses can be easily analyzed.
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Affiliation(s)
- Néli José da Fonseca
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais (UFMG), Av. Antônio Carlos, 6627, Belo Horizonte, 31270-901, Brazil.
| | - Marcelo Querino Lima Afonso
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais (UFMG), Av. Antônio Carlos, 6627, Belo Horizonte, 31270-901, Brazil.
| | - Natan Gonçalves Pedersolli
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais (UFMG), Av. Antônio Carlos, 6627, Belo Horizonte, 31270-901, Brazil.
| | - Lucas Carrijo de Oliveira
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais (UFMG), Av. Antônio Carlos, 6627, Belo Horizonte, 31270-901, Brazil.
| | - Dhiego Souto Andrade
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais (UFMG), Av. Antônio Carlos, 6627, Belo Horizonte, 31270-901, Brazil.
| | - Lucas Bleicher
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais (UFMG), Av. Antônio Carlos, 6627, Belo Horizonte, 31270-901, Brazil.
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10
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Brecher MB, Li Z, Zhang J, Chen H, Lin Q, Liu B, Li H. Refolding of a fully functional flavivirus methyltransferase revealed that S-adenosyl methionine but not S-adenosyl homocysteine is copurified with flavivirus methyltransferase. Protein Sci 2014; 24:117-28. [PMID: 25352331 DOI: 10.1002/pro.2594] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 10/22/2014] [Accepted: 10/23/2014] [Indexed: 01/09/2023]
Abstract
Methylation of flavivirus RNA is vital for its stability and translation in the infected host cell. This methylation is mediated by the flavivirus methyltransferase (MTase), which methylates the N7 and 2'-O positions of the viral RNA cap by using S-adenosyl-l-methionine (SAM) as a methyl donor. In this report, we demonstrate that SAM, in contrast to the reaction by-product S-adenosyl-l-homocysteine, which was assumed previously, is copurified with the Dengue (DNV) and West Nile virus MTases produced in Escherichia coli (E. coli). This endogenous SAM can be removed by denaturation and refolding of the MTase protein. The refolded MTase of DNV serotype 3 (DNV3) displays methylation activity comparable to native enzyme, and its crystal structure at 2.1 Å is almost identical to that of native MTase. We characterized the binding of Sinefungin (SIN), a previously described SAM-analog inhibitor of MTase function, to the native and refolded DNV3 MTase by isothermal titration calorimetry, and found that SIN binds to refolded MTase with more than 16 times the affinity of SIN binding to the MTase purified natively. Moreover, we show that SAM is also copurified with other flavivirus MTases, indicating that purification by refolding may be a generally applicable tool for studying flavivirus MTase inhibition.
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Affiliation(s)
- Matthew B Brecher
- Wadsworth Center, New York State Department of Health, Albany, New York, 12208
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11
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Bussetta C, Choi KH. Dengue virus nonstructural protein 5 adopts multiple conformations in solution. Biochemistry 2012; 51:5921-31. [PMID: 22757685 PMCID: PMC3448003 DOI: 10.1021/bi300406n] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Dengue virus (DENV) nonstructural protein 5 (NS5) is composed of two globular domains separated by a 10-residue linker. The N-terminal domain participates in the synthesis of a mRNA cap 1 structure ((7Me)GpppA(2'OMe)) at the 5' end of the viral genome and possesses guanylyltransferase, guanine-N7-methyltransferase, and nucleoside-2'O-methyltransferase activities. The C-terminal domain is an RNA-dependent RNA polymerase responsible for viral RNA synthesis. Although crystal structures of the two isolated domains have been obtained, there are no structural data for full-length NS5. It is also unclear whether the two NS5 domains interact with each other to form a stable structure in which the relative orientation of the two domains is fixed. To investigate the structure and dynamics of DENV type 3 NS5 in solution, we conducted small-angle X-ray scattering experiments with the full-length protein. NS5 was found to be monomeric and well-folded under the conditions tested. The results of these experiments also suggest that NS5 adopts multiple conformations in solution, ranging from compact to more extended forms in which the two domains do not seem to interact with each other. We interpret the multiple conformations of NS5 observed in solution as resulting from weak interactions between the two NS5 domains and flexibility of the linker in the absence of other components of the replication complex.
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Affiliation(s)
- Cécile Bussetta
- Department of Biochemistry & Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch at Galveston, Galveston, TX 77555-0647
| | - Kyung H. Choi
- Department of Biochemistry & Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch at Galveston, Galveston, TX 77555-0647
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12
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Abstract
Many flaviviruses are significant human pathogens. The plus-strand RNA genome of a flavivirus contains a 5' terminal cap 1 structure (m(7)GpppAmG). The flavivirus encodes one methyltransferase (MTase), located at the N-terminal portion of the NS5 RNA-dependent RNA polymerase (RdRp). Here we review recent advances in our understanding of flaviviral capping machinery and the implications for drug development. The NS5 MTase catalyzes both guanine N7 and ribose 2'-OH methylations during viral cap formation. Representative flavivirus MTases, from dengue, yellow fever, and West Nile virus (WNV), sequentially generate GpppA → m(7)GpppA → m(7)GpppAm. Despite the existence of two distinct methylation activities, the crystal structures of flavivirus MTases showed a single binding site for S-adenosyl-L-methionine (SAM), the methyl donor. This finding indicates that the substrate GpppA-RNA must be repositioned to accept the N7 and 2'-O methyl groups from SAM during the sequential reactions. Further studies demonstrated that distinct RNA elements are required for the methylations of guanine N7 on the cap and of ribose 2'-OH on the first transcribed nucleotide. Mutant enzymes with different methylation defects can trans complement one another in vitro, demonstrating that separate molecules of the enzyme can independently catalyze the two cap methylations in vitro. In the context of the infectious virus, defects in both methylations, or a defect in the N7 methylation alone, are lethal to WNV. However, viruses defective solely in 2'-O methylation are attenuated and can protect mice from later wild-type WNV challenge. The results demonstrate that the N7 methylation activity is essential for the WNV life cycle and, thus, methyltransferase represents a novel and promising target for flavivirus therapy.
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13
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Dong H, Liu L, Zou G, Zhao Y, Li Z, Lim SP, Shi PY, Li H. Structural and functional analyses of a conserved hydrophobic pocket of flavivirus methyltransferase. J Biol Chem 2010; 285:32586-95. [PMID: 20685660 DOI: 10.1074/jbc.m110.129197] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The flavivirus methyltransferase (MTase) sequentially methylates the N7 and 2'-O positions of the viral RNA cap (GpppA-RNA → m(7)GpppA-RNA → m(7)GpppAm-RNA), using S-adenosyl-l-methionine (AdoMet) as a methyl donor. We report here that sinefungin (SIN), an AdoMet analog, inhibits several flaviviruses through suppression of viral MTase. The crystal structure of West Nile virus MTase in complex with SIN inhibitor at 2.0-Å resolution revealed a flavivirus-conserved hydrophobic pocket located next to the AdoMet-binding site. The pocket is functionally critical in the viral replication and cap methylations. In addition, the N7 methylation efficiency was found to correlate with the viral replication ability. Thus, SIN analogs with modifications that interact with the hydrophobic pocket are potential specific inhibitors of flavivirus MTase.
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Affiliation(s)
- Hongping Dong
- Wadsworth Center, New York State Department of Health, Albany, New York 12201, USA
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Bollati M, Alvarez K, Assenberg R, Baronti C, Canard B, Cook S, Coutard B, Decroly E, de Lamballerie X, Gould EA, Grard G, Grimes JM, Hilgenfeld R, Jansson AM, Malet H, Mancini EJ, Mastrangelo E, Mattevi A, Milani M, Moureau G, Neyts J, Owens RJ, Ren J, Selisko B, Speroni S, Steuber H, Stuart DI, Unge T, Bolognesi M. Structure and functionality in flavivirus NS-proteins: perspectives for drug design. Antiviral Res 2010; 87:125-48. [PMID: 19945487 PMCID: PMC3918146 DOI: 10.1016/j.antiviral.2009.11.009] [Citation(s) in RCA: 241] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2009] [Revised: 09/08/2009] [Accepted: 11/21/2009] [Indexed: 12/28/2022]
Abstract
Flaviviridae are small enveloped viruses hosting a positive-sense single-stranded RNA genome. Besides yellow fever virus, a landmark case in the history of virology, members of the Flavivirus genus, such as West Nile virus and dengue virus, are increasingly gaining attention due to their re-emergence and incidence in different areas of the world. Additional environmental and demographic considerations suggest that novel or known flaviviruses will continue to emerge in the future. Nevertheless, up to few years ago flaviviruses were considered low interest candidates for drug design. At the start of the European Union VIZIER Project, in 2004, just two crystal structures of protein domains from the flaviviral replication machinery were known. Such pioneering studies, however, indicated the flaviviral replication complex as a promising target for the development of antiviral compounds. Here we review structural and functional aspects emerging from the characterization of two main components (NS3 and NS5 proteins) of the flavivirus replication complex. Most of the reviewed results were achieved within the European Union VIZIER Project, and cover topics that span from viral genomics to structural biology and inhibition mechanisms. The ultimate aim of the reported approaches is to shed light on the design and development of antiviral drug leads.
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Affiliation(s)
- Michela Bollati
- Department of Biomolecular Sciences and Biotechnology, University of Milano, Via Celoria 26, 20133 Milano, Italy
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