1
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Dangerfield TL, Paik I, Bhadra S, Johnson KA, Ellington A. Kinetics of elementary steps in loop-mediated isothermal amplification (LAMP) show that strand invasion during initiation is rate-limiting. Nucleic Acids Res 2023; 51:488-499. [PMID: 36583345 PMCID: PMC9841402 DOI: 10.1093/nar/gkac1221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 12/05/2022] [Accepted: 12/09/2022] [Indexed: 12/31/2022] Open
Abstract
Loop-mediated isothermal amplification (LAMP) has proven to be easier to implement than PCR for point-of-care diagnostic tests. However, the underlying mechanism of LAMP is complicated and the kinetics of the major steps in LAMP have not been fully elucidated, which prevents rational improvements in assay development. Here we present our work to characterize the kinetics of the elementary steps in LAMP and show that: (i) strand invasion / initiation is the rate-limiting step in the LAMP reaction; (ii) the loop primer plays an important role in accelerating the rate of initiation and does not function solely during the exponential amplification phase and (iii) strand displacement synthesis by Bst-LF polymerase is relatively fast (125 nt/s) and processive on both linear and hairpin templates, although with some interruptions on high GC content templates. Building on these data, we were able to develop a kinetic model that relates the individual kinetic experiments to the bulk LAMP reaction. The assays developed here provide important insights into the mechanism of LAMP, and the overall model should be crucial in engineering more sensitive and faster LAMP reactions. The kinetic methods we employ should likely prove useful with other isothermal DNA amplification methods.
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Affiliation(s)
- Tyler L Dangerfield
- Department of Molecular Biosciences, College of Natural Sciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Inyup Paik
- Department of Molecular Biosciences, College of Natural Sciences, University of Texas at Austin, Austin, TX 78712, USA
- Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Sanchita Bhadra
- Department of Molecular Biosciences, College of Natural Sciences, University of Texas at Austin, Austin, TX 78712, USA
- Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Kenneth A Johnson
- Department of Molecular Biosciences, College of Natural Sciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Andrew D Ellington
- Department of Molecular Biosciences, College of Natural Sciences, University of Texas at Austin, Austin, TX 78712, USA
- Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX 78712, USA
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2
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Structural basis of transition from initiation to elongation in de novo viral RNA-dependent RNA polymerases. Proc Natl Acad Sci U S A 2023; 120:e2211425120. [PMID: 36577062 PMCID: PMC9910504 DOI: 10.1073/pnas.2211425120] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
De novo viral RNA-dependent RNA polymerases (RdRPs) utilize their priming element (PE) to facilitate accurate initiation. Upon transition to elongation, the PE has to retreat from the active site to give room to the template-product RNA duplex. However, PE conformational change upon this transition and the role of PE at elongation both remain elusive. Here, we report crystal structures of RdRP elongation complex (EC) from dengue virus serotype 2 (DENV2), demonstrating a dramatic refolding of PE that allows establishment of interactions with the RNA duplex backbone approved to be essential for EC stability. Enzymology data from both DENV2 and hepatitis C virus (HCV) RdRPs suggest that critical transition of the refolding likely occurs after synthesis of a 4- to 5-nucleotide (nt) product together providing a key basis in understanding viral RdRP transition from initiation to elongation.
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3
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Abstract
The therapeutic targeting of the nonstructural protein 5B (NS5B) RNA-dependent RNA polymerase (RdRp) of the Hepatitis C Virus (HCV) with nucleotide analogs led to a deep understanding of this enzymes structure, function and substrate specificity. Unlike previously studied DNA polymerases including the reverse transcriptase of Human Immunodeficiency Virus, development of biochemical assays for HCV RdRp proved challenging due to low solubility of the full-length protein and inefficient acceptance of exogenous primer/templates. Despite the poor apparent specific activity, HCV RdRp was found to support rapid and processive transcription once elongation is initiated in vitro consistent with its high level of viral replication in the livers of patients. Understanding of the substrate specificity of HCV RdRp led to the discovery of the active triphosphate of sofosbuvir as a nonobligate chain-terminator of viral RNA transcripts. The ternary crystal structure of HCV RdRp, primer/template, and incoming nucleotide showed the interaction between the nucleotide analog and the 2'-hydroxyl binding pocket and how an unfit mutation of serine 282 to threonine results in resistance by interacting with the uracil base and modified 2'-position of the analog. Host polymerases mediate off-target toxicity of nucleotide analogs and the active metabolite of sofosbuvir was found to not be efficiently incorporated by host polymerases including the mitochondrial RNA polymerase (POLRMT). Knowledge from studying inhibitors of HCV RdRp serves to advance antiviral drug discovery for other emerging RNA viruses including the discovery of remdesivir as an inhibitor of severe acute respiratory syndrome coronavirus 2 (SARS-CoV2), the virus that causes COVID-19.
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Affiliation(s)
- Joy Y Feng
- Gilead Sciences, Inc., Foster City, CA, United States.
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4
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Zhang BY, Liu W, Jia H, Lu G, Gong P. An induced-fit de novo initiation mechanism suggested by a pestivirus RNA-dependent RNA polymerase. Nucleic Acids Res 2021; 49:8811-8821. [PMID: 34365500 PMCID: PMC8421227 DOI: 10.1093/nar/gkab666] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Revised: 07/15/2021] [Accepted: 08/06/2021] [Indexed: 01/09/2023] Open
Abstract
Viral RNA-dependent RNA polymerases (RdRPs) play central roles in the genome replication and transcription processes of RNA viruses. RdRPs initiate RNA synthesis either in primer-dependent or de novo mechanism, with the latter often assisted by a 'priming element' (PE) within the RdRP thumb domain. However, RdRP PEs exhibit high-level structural diversity, making it difficult to reconcile their conserved function in de novo initiation. Here we determined a 3.1-Å crystal structure of the Flaviviridae classical swine fever virus (CSFV) RdRP with a relative complete PE. Structure-based mutagenesis in combination with enzymology data further highlights the importance of a glycine residue (G671) and the participation of residues 665-680 in RdRP initiation. When compared with other representative Flaviviridae RdRPs, CSFV RdRP PE is structurally distinct but consistent in terminal initiation preference. Taken together, our work suggests that a conformational change in CSFV RdRP PE is necessary to fulfill de novo initiation, and similar 'induced-fit' mechanisms may be commonly taken by PE-containing de novo viral RdRPs.
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Affiliation(s)
| | - Weichi Liu
- Correspondence may also be addressed to Weichi Liu.
| | - Hengxia Jia
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, No.44 Xiao Hong Shan, Wuhan, Hubei 430071, China,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Guoliang Lu
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, No.44 Xiao Hong Shan, Wuhan, Hubei 430071, China
| | - Peng Gong
- To whom correspondence should be addressed. Tel: +86 27 87197578; Fax: +86 27 87197578;
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5
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Proline to Threonine Mutation at Position 162 of NS5B of Classical Swine Fever Virus Vaccine C Strain Promoted Genome Replication and Infectious Virus Production by Facilitating Initiation of RNA Synthesis. Viruses 2021; 13:v13081523. [PMID: 34452387 PMCID: PMC8402891 DOI: 10.3390/v13081523] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 07/29/2021] [Accepted: 07/30/2021] [Indexed: 12/11/2022] Open
Abstract
The 3′untranslated region (3′UTR) and NS5B of classical swine fever virus (CSFV) play vital roles in viral genome replication. In this study, two chimeric viruses, vC/SM3′UTR and vC/b3′UTR, with 3′UTR substitution of CSFV Shimen strain or bovine viral diarrhea virus (BVDV) NADL strain, were constructed based on the infectious cDNA clone of CSFV vaccine C strain, respectively. After virus rescue, each recombinant chimeric virus was subjected to continuous passages in PK-15 cells. The representative passaged viruses were characterized and sequenced. Serial passages resulted in generation of mutations and the passaged viruses exhibited significantly increased genomic replication efficiency and infectious virus production compared to parent viruses. A proline to threonine mutation at position 162 of NS5B was identified in both passaged vC/SM3′UTR and vC/b3′UTR. We generated P162T mutants of two chimeras using the reverse genetics system, separately. The single P162T mutation in NS5B of vC/SM3′UTR or vC/b3′UTR played a key role in increased viral genome replication and infectious virus production. The P162T mutation increased vC/SM3′UTRP162T replication in rabbits. From RNA-dependent RNA polymerase (RdRp) assays in vitro, the NS5B containing P162T mutation (NS5BP162T) exhibited enhanced RdRp activity for different RNA templates. We further identified that the enhanced RdRp activity originated from increased initiation efficiency of RNA synthesis. These findings revealed a novel function for the NS5B residue 162 in modulating pestivirus replication.
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Tarannum H, Chauhan B, Samadder A, Roy H, Nandi S. To Explore the Potential Targets and Current Structure-based Design Strategies Utilizing Co-crystallized Ligand to Combat HCV. Curr Drug Targets 2021; 22:590-604. [PMID: 32720601 DOI: 10.2174/1389450121999200727215020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 05/05/2020] [Accepted: 05/11/2020] [Indexed: 11/22/2022]
Abstract
BACKGROUND Hepatitis C Virus (HCV) belongs to the Hepacivirus family. HCV has been designated as a very dreadful virus as it can attack the liver, causing inflammation and even may lead to cancer in chronic conditions. It was estimated that 71 million people around the world have chronic HCV infection. World Health Organization (WHO) reported that about 399000 people died because of chronic cirrhosis and liver cancer globally. In spite of the abundance of availability of drugs for the treatment of HCV, however, the issue of drug resistance surpasses all the possibilities of therapeutic management of HCV. Therefore, to address this issue of 'drug-resistance', various HCV targets were explored to quest the evaluation of the mechanism of the disease progression. METHODS An attempt has been made in the present study to explore the various targets of HCV involved in the mechanism(s) of the disease initiation and progression and to focus on the mode of binding of ligands, which are co-crystallized at the active cavity of different HCV targets. CONCLUSION The present study could predict some crucial features of these ligands, which possibly interacted with various amino acid residues responsible for their biological activity and molecular signaling pathway(s). Such binding mode may be considered as a template for the high throughput screening and designing of active congeneric ligands to combat HCV.
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Affiliation(s)
- Heena Tarannum
- Department of Pharmaceutical Chemistry, Global Institute of Pharmaceutical Education and Research (Affiliated to Uttarakhand Technical University), Kashipur-244713, India
| | - Bhumika Chauhan
- Department of Pharmaceutical Chemistry, Global Institute of Pharmaceutical Education and Research (Affiliated to Uttarakhand Technical University), Kashipur-244713, India
| | - Asmita Samadder
- Cytogenetics and Molecular Biology Lab., Department of Zoology, University of Kalyani, Kalyani, Nadia, 741235, India
| | - Harekrishna Roy
- Nirmala College of Pharmacy, Mangalagiri, Guntur, Andhra Pradesh, 522503, India
| | - Sisir Nandi
- Department of Pharmaceutical Chemistry, Global Institute of Pharmaceutical Education and Research (Affiliated to Uttarakhand Technical University), Kashipur-244713, India
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7
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Li HC, Yang CH, Lo SY. Hepatitis C Viral Replication Complex. Viruses 2021; 13:v13030520. [PMID: 33809897 PMCID: PMC8004249 DOI: 10.3390/v13030520] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 03/18/2021] [Accepted: 03/19/2021] [Indexed: 12/16/2022] Open
Abstract
The life cycle of the hepatitis C virus (HCV) can be divided into several stages, including viral entry, protein translation, RNA replication, viral assembly, and release. HCV genomic RNA replication occurs in the replication organelles (RO) and is tightly linked to ER membrane alterations containing replication complexes (proteins NS3 to NS5B). The amplification of HCV genomic RNA could be regulated by the RO biogenesis, the viral RNA structure (i.e., cis-acting replication elements), and both viral and cellular proteins. Studies on HCV replication have led to the development of direct-acting antivirals (DAAs) targeting the replication complex. This review article summarizes the viral and cellular factors involved in regulating HCV genomic RNA replication and the DAAs that inhibit HCV replication.
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Affiliation(s)
- Hui-Chun Li
- Department of Biochemistry, Tzu Chi University, Hualien 97004, Taiwan;
| | - Chee-Hing Yang
- Department of Laboratory Medicine and Biotechnology, Tzu Chi University, Hualien 97004, Taiwan;
| | - Shih-Yen Lo
- Department of Laboratory Medicine and Biotechnology, Tzu Chi University, Hualien 97004, Taiwan;
- Department of Laboratory Medicine, Buddhist Tzu Chi General Hospital, Hualien 97004, Taiwan
- Correspondence: ; Tel.: +886-3-8565301 (ext. 2322)
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8
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Yang J, Jing X, Yi W, Li XD, Yao C, Zhang B, Zheng Z, Wang H, Gong P. Crystal structure of a tick-borne flavivirus RNA-dependent RNA polymerase suggests a host adaptation hotspot in RNA viruses. Nucleic Acids Res 2021; 49:1567-1580. [PMID: 33406260 PMCID: PMC7897508 DOI: 10.1093/nar/gkaa1250] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 12/09/2020] [Accepted: 12/15/2020] [Indexed: 01/07/2023] Open
Abstract
The RNA-dependent RNA polymerases (RdRPs) encoded by RNA viruses represent a unique class of nucleic acid polymerases. RdRPs are essential in virus life cycle due to their central role in viral genome replication/transcription processes. However, their contribution in host adaption has not been well documented. By solving the RdRP crystal structure of the tick-borne encephalitis virus (TBEV), a tick-borne flavivirus, and comparing the structural and sequence features with mosquito-borne flavivirus RdRPs, we found that a region between RdRP catalytic motifs B and C, namely region B-C, clearly bears host-related diversity. Inter-virus substitutions of region B-C sequence were designed in both TBEV and mosquito-borne Japanese encephalitis virus backbones. While region B-C substitutions only had little or moderate effect on RdRP catalytic activities, virus proliferation was not supported by these substitutions in both virus systems. Importantly, a TBEV replicon-derived viral RNA replication was significantly reduced but not abolished by the substitution, suggesting the involvement of region B-C in viral and/or host processes beyond RdRP catalysis. A systematic structural analysis of region B-C in viral RdRPs further emphasizes its high level of structure and length diversity, providing a basis to further refine its relevance in RNA virus-host interactions in a general context.
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Affiliation(s)
| | | | - Wenfu Yi
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, No.44 Xiao Hong Shan, Wuhan, Hubei 430071, China
| | - Xiao-Dan Li
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, No.44 Xiao Hong Shan, Wuhan, Hubei 430071, China
| | - Chen Yao
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, No.44 Xiao Hong Shan, Wuhan, Hubei 430071, China,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Bo Zhang
- Correspondence may also be addressed to Bo Zhang.
| | - Zhenhua Zheng
- Correspondence may also be addressed to Zhenhua Zheng.
| | | | - Peng Gong
- To whom correspondence should be addressed. Tel: +86 27 87197578; Fax: +86 27 87197578;
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9
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Shannon A, Selisko B, Le NTT, Huchting J, Touret F, Piorkowski G, Fattorini V, Ferron F, Decroly E, Meier C, Coutard B, Peersen O, Canard B. Rapid incorporation of Favipiravir by the fast and permissive viral RNA polymerase complex results in SARS-CoV-2 lethal mutagenesis. Nat Commun 2020; 11:4682. [PMID: 32943628 PMCID: PMC7499305 DOI: 10.1038/s41467-020-18463-z] [Citation(s) in RCA: 169] [Impact Index Per Article: 42.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 08/10/2020] [Indexed: 12/13/2022] Open
Abstract
The ongoing Corona Virus Disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has emphasized the urgent need for antiviral therapeutics. The viral RNA-dependent-RNA-polymerase (RdRp) is a promising target with polymerase inhibitors successfully used for the treatment of several viral diseases. We demonstrate here that Favipiravir predominantly exerts an antiviral effect through lethal mutagenesis. The SARS-CoV RdRp complex is at least 10-fold more active than any other viral RdRp known. It possesses both unusually high nucleotide incorporation rates and high-error rates allowing facile insertion of Favipiravir into viral RNA, provoking C-to-U and G-to-A transitions in the already low cytosine content SARS-CoV-2 genome. The coronavirus RdRp complex represents an Achilles heel for SARS-CoV, supporting nucleoside analogues as promising candidates for the treatment of COVID-19.
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Affiliation(s)
- Ashleigh Shannon
- Architecture et Fonction des Macromolécules Biologiques, CNRS and Aix-Marseille Université, UMR 7257, 13009, Marseille, France
| | - Barbara Selisko
- Architecture et Fonction des Macromolécules Biologiques, CNRS and Aix-Marseille Université, UMR 7257, 13009, Marseille, France
| | - Nhung-Thi-Tuyet Le
- Architecture et Fonction des Macromolécules Biologiques, CNRS and Aix-Marseille Université, UMR 7257, 13009, Marseille, France
| | - Johanna Huchting
- Faculty of Sciences, Department of Chemistry, Organic Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, D-20146, Hamburg, Germany
| | - Franck Touret
- Unité des Virus Émergents (UVE: Aix-Marseille Univ - IRD 190 - Inserm 1207 - IHU Méditerranée Infection), Marseille, France
| | - Géraldine Piorkowski
- Unité des Virus Émergents (UVE: Aix-Marseille Univ - IRD 190 - Inserm 1207 - IHU Méditerranée Infection), Marseille, France
| | - Véronique Fattorini
- Architecture et Fonction des Macromolécules Biologiques, CNRS and Aix-Marseille Université, UMR 7257, 13009, Marseille, France
| | - François Ferron
- Architecture et Fonction des Macromolécules Biologiques, CNRS and Aix-Marseille Université, UMR 7257, 13009, Marseille, France
| | - Etienne Decroly
- Architecture et Fonction des Macromolécules Biologiques, CNRS and Aix-Marseille Université, UMR 7257, 13009, Marseille, France
| | - Chris Meier
- Faculty of Sciences, Department of Chemistry, Organic Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, D-20146, Hamburg, Germany
| | - Bruno Coutard
- Unité des Virus Émergents (UVE: Aix-Marseille Univ - IRD 190 - Inserm 1207 - IHU Méditerranée Infection), Marseille, France
| | - Olve Peersen
- Department of Biochemistry & Molecular Biology, Colorado State University, Fort Collins, CO, 80523-1870, USA.
| | - Bruno Canard
- Architecture et Fonction des Macromolécules Biologiques, CNRS and Aix-Marseille Université, UMR 7257, 13009, Marseille, France.
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10
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Villalba B, Johnson KA. Rate-limiting pyrophosphate release by hepatitis C virus polymerase NS5B improves fidelity. J Biol Chem 2020; 295:16436-16444. [PMID: 32938715 DOI: 10.1074/jbc.ra120.015394] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Revised: 09/04/2020] [Indexed: 01/02/2023] Open
Abstract
The hepatitis C virus RNA-dependent RNA polymerase NS5B is responsible for the replication of the viral genome. Previous studies have uncovered NTP-mediated excision mechanisms that may be responsible for aiding in maintaining fidelity (the frequency of incorrect incorporation events relative to correct), but little is known about the fidelity of NS5B. In this study, we used transient-state kinetics to examine the mechanistic basis for polymerase fidelity. We observe a wide range of efficiency for incorporation of various mismatched base pairs and have uncovered a mechanism in which the rate constant for pyrophosphate release is slowed for certain misincorporation events. This results in an increase in fidelity against these specific misincorporations. Furthermore, we discover that some mismatches are highly unfavorable and cannot be observed under the conditions used here. The calculated fidelity of NS5B ranges between 10-4-10-9 for different mismatches.
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Affiliation(s)
- Brian Villalba
- Institutes for Cell and Molecular Biology, University of Texas at Austin, Austin, Texas, USA
| | - Kenneth A Johnson
- Institutes for Cell and Molecular Biology, University of Texas at Austin, Austin, Texas, USA.
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11
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Hecel A, Ostrowska M, Stokowa-Sołtys K, Wątły J, Dudek D, Miller A, Potocki S, Matera-Witkiewicz A, Dominguez-Martin A, Kozłowski H, Rowińska-Żyrek M. Zinc(II)-The Overlooked Éminence Grise of Chloroquine's Fight against COVID-19? Pharmaceuticals (Basel) 2020; 13:E228. [PMID: 32882888 PMCID: PMC7558363 DOI: 10.3390/ph13090228] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 08/28/2020] [Accepted: 08/29/2020] [Indexed: 12/24/2022] Open
Abstract
Zn(II) is an inhibitor of SARS-CoV-2's RNA-dependent RNA polymerase, and chloroquine and hydroxychloroquine are Zn(II) ionophores-this statement gives a curious mind a lot to think about. We show results of the first clinical trials on chloroquine (CQ) and hydroxychloroquine (HCQ) in the treatment of COVID-19, as well as earlier reports on the anticoronaviral properties of these two compounds and of Zn(II) itself. Other FDA-approved Zn(II) ionophores are given a decent amount of attention and are thought of as possible COVID-19 therapeutics.
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Affiliation(s)
- Aleksandra Hecel
- Faculty of Chemistry, University of Wroclaw, F. Joliot-Curie 14, 50-383 Wroclaw, Poland; (A.H.); (M.O.); (K.S.-S.); (J.W.); (D.D.); (A.M.); (S.P.); (H.K.)
| | - Małgorzata Ostrowska
- Faculty of Chemistry, University of Wroclaw, F. Joliot-Curie 14, 50-383 Wroclaw, Poland; (A.H.); (M.O.); (K.S.-S.); (J.W.); (D.D.); (A.M.); (S.P.); (H.K.)
| | - Kamila Stokowa-Sołtys
- Faculty of Chemistry, University of Wroclaw, F. Joliot-Curie 14, 50-383 Wroclaw, Poland; (A.H.); (M.O.); (K.S.-S.); (J.W.); (D.D.); (A.M.); (S.P.); (H.K.)
| | - Joanna Wątły
- Faculty of Chemistry, University of Wroclaw, F. Joliot-Curie 14, 50-383 Wroclaw, Poland; (A.H.); (M.O.); (K.S.-S.); (J.W.); (D.D.); (A.M.); (S.P.); (H.K.)
| | - Dorota Dudek
- Faculty of Chemistry, University of Wroclaw, F. Joliot-Curie 14, 50-383 Wroclaw, Poland; (A.H.); (M.O.); (K.S.-S.); (J.W.); (D.D.); (A.M.); (S.P.); (H.K.)
| | - Adriana Miller
- Faculty of Chemistry, University of Wroclaw, F. Joliot-Curie 14, 50-383 Wroclaw, Poland; (A.H.); (M.O.); (K.S.-S.); (J.W.); (D.D.); (A.M.); (S.P.); (H.K.)
| | - Sławomir Potocki
- Faculty of Chemistry, University of Wroclaw, F. Joliot-Curie 14, 50-383 Wroclaw, Poland; (A.H.); (M.O.); (K.S.-S.); (J.W.); (D.D.); (A.M.); (S.P.); (H.K.)
| | - Agnieszka Matera-Witkiewicz
- Screening Laboratory of Biological Activity Tests and Collection of Biological Material, Faculty of Pharmacy, Wroclaw Medical University, Borowska 211A, 50-556 Wroclaw, Poland;
| | - Alicia Dominguez-Martin
- Department of Inorganic Chemistry, Faculty of Pharmacy, University of Granada, E-18071 Granada, Spain;
| | - Henryk Kozłowski
- Faculty of Chemistry, University of Wroclaw, F. Joliot-Curie 14, 50-383 Wroclaw, Poland; (A.H.); (M.O.); (K.S.-S.); (J.W.); (D.D.); (A.M.); (S.P.); (H.K.)
- Department of Physiotherapy, Opole Medical School, Katowicka 68, 40-060 Opole, Poland
| | - Magdalena Rowińska-Żyrek
- Faculty of Chemistry, University of Wroclaw, F. Joliot-Curie 14, 50-383 Wroclaw, Poland; (A.H.); (M.O.); (K.S.-S.); (J.W.); (D.D.); (A.M.); (S.P.); (H.K.)
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12
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Sternberg A, McKee DL, Naujokat C. Novel Drugs Targeting the SARS-CoV-2/COVID-19 Machinery. Curr Top Med Chem 2020; 20:1423-1433. [PMID: 32416679 DOI: 10.2174/1568026620999200517043137] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 05/15/2020] [Accepted: 05/16/2020] [Indexed: 12/13/2022]
Abstract
Like other human pathogenic viruses, coronavirus SARS-CoV-2 employs sophisticated macromolecular machines for viral host cell entry, genome replication and protein processing. Such machinery encompasses SARS-CoV-2 envelope spike (S) glycoprotein required for host cell entry by binding to the ACE2 receptor, viral RNA-dependent RNA polymerase (RdRp) and 3-chymotrypsin-like main protease (3Clpro/Mpro). Under the pressure of the accelerating COVID-19 pandemic caused by the outbreak of SARS-CoV-2 in Wuhan, China in December 2019, novel and repurposed drugs were recently designed and identified for targeting the SARS-CoV-2 reproduction machinery, with the aim to limit the spread of SARS-CoV-2 and morbidity and mortality due to the COVID-19 pandemic.
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Affiliation(s)
- Ariane Sternberg
- Center and Network for Targeted Oncology, Muehlackerweg 8, D-69239 Heidelberg, Germany
| | | | - Cord Naujokat
- Institute of Immunology, University of Heidelberg, Im Neuenheimer Feld 305, D-69120 Heidelberg, Germany
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13
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Villalba B, Li J, Johnson KA. Resistance to excision determines efficiency of hepatitis C virus RNA-dependent RNA polymerase inhibition by nucleotide analogs. J Biol Chem 2020; 295:10112-10124. [PMID: 32457046 DOI: 10.1074/jbc.ra120.013422] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 05/11/2020] [Indexed: 12/26/2022] Open
Abstract
NS5B is the RNA-dependent RNA polymerase that catalyzes the replication of the hepatitis C virus genome. It is a major target for antiviral drugs including nucleoside analogs, such as the prodrugs mericitabine and sofosbuvir, which get metabolized to 2'-fluoro-2'C-methylcytidine-5'-triphosphate and 2'-fluoro-2'C-methyluridine-5'-triphosphate, respectively. These analogs act as chain terminators after they are incorporated during RNA synthesis. Recently, it has been shown that NS5B can efficiently remove chain terminators by a nucleotide-mediated excision reaction that rescues RNA synthesis. In this study, we use transient-state kinetics to understand the efficiency of inhibition for five nucleoside analogs. We show that CTP analogs are readily incorporated into a growing primer by NS5B but are also efficiently excised. In contrast, although UMP analogs are more slowly incorporated, the excision of UMP is slow and inefficient, and modifications to the 2'-carbon of the UTP ribose ring further decreased rates of excision to an undetectable level. Taken together, these data suggest that the clinical effectiveness of sofosbuvir is largely a function of being intractable to nucleotide-mediated excision compared with similar nucleoside analogs.
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Affiliation(s)
- Brian Villalba
- Department of Molecular Biosciences, University of Texas, Austin, Texas, USA
| | - Jiawen Li
- Department of Molecular Biosciences, University of Texas, Austin, Texas, USA
| | - Kenneth A Johnson
- Department of Molecular Biosciences, University of Texas, Austin, Texas, USA
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14
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Shannon A, Selisko B, Le NTT, Huchting J, Touret F, Piorkowski G, Fattorini V, Ferron F, Decroly E, Meier C, Coutard B, Peersen O, Canard B. Favipiravir strikes the SARS-CoV-2 at its Achilles heel, the RNA polymerase. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2020:2020.05.15.098731. [PMID: 32511380 PMCID: PMC7263509 DOI: 10.1101/2020.05.15.098731] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The ongoing Corona Virus Disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has emphasized the urgent need for antiviral therapeutics. The viral RNA-dependent-RNA-polymerase (RdRp) is a promising target with polymerase inhibitors successfully used for the treatment of several viral diseases. Here we show that Favipiravir exerts an antiviral effect as a nucleotide analogue through a combination of chain termination, slowed RNA synthesis and lethal mutagenesis. The SARS-CoV RdRp complex is at least 10-fold more active than any other viral RdRp known. It possesses both unusually high nucleotide incorporation rates and high-error rates allowing facile insertion of Favipiravir into viral RNA, provoking C-to-U and G-to-A transitions in the already low cytosine content SARS-CoV-2 genome. The coronavirus RdRp complex represents an Achilles heel for SARS-CoV, supporting nucleoside analogues as promising candidates for the treatment of COVID-19.
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Affiliation(s)
- A. Shannon
- Architecture et Fonction des Macromolécules Biologiques, CNRS and Aix-Marseille Université, UMR 7257, Polytech Case 925, 13009 Marseille, France
| | - B. Selisko
- Architecture et Fonction des Macromolécules Biologiques, CNRS and Aix-Marseille Université, UMR 7257, Polytech Case 925, 13009 Marseille, France
| | - NTT Le
- Architecture et Fonction des Macromolécules Biologiques, CNRS and Aix-Marseille Université, UMR 7257, Polytech Case 925, 13009 Marseille, France
| | - J. Huchting
- University of Hamburg, Faculty of Sciences, Department of Chemistry, Organic Chemistry, Martin-Luther-King-Platz 6, D-20146 Hamburg, Germany
| | - F. Touret
- Unité des Virus Émergents (UVE: Aix-Marseille Univ - IRD 190 - Inserm 1207 - IHU Méditerranée Infection), Marseille, France
| | - G. Piorkowski
- Unité des Virus Émergents (UVE: Aix-Marseille Univ - IRD 190 - Inserm 1207 - IHU Méditerranée Infection), Marseille, France
| | - V. Fattorini
- Architecture et Fonction des Macromolécules Biologiques, CNRS and Aix-Marseille Université, UMR 7257, Polytech Case 925, 13009 Marseille, France
| | - F. Ferron
- Architecture et Fonction des Macromolécules Biologiques, CNRS and Aix-Marseille Université, UMR 7257, Polytech Case 925, 13009 Marseille, France
| | - E. Decroly
- Architecture et Fonction des Macromolécules Biologiques, CNRS and Aix-Marseille Université, UMR 7257, Polytech Case 925, 13009 Marseille, France
| | - C Meier
- University of Hamburg, Faculty of Sciences, Department of Chemistry, Organic Chemistry, Martin-Luther-King-Platz 6, D-20146 Hamburg, Germany
| | - B. Coutard
- Unité des Virus Émergents (UVE: Aix-Marseille Univ - IRD 190 - Inserm 1207 - IHU Méditerranée Infection), Marseille, France
| | - O. Peersen
- Department of Biochemistry & Molecular Biology, Colorado State University, Fort Collins, CO 80523-1870, USA
| | - B. Canard
- Architecture et Fonction des Macromolécules Biologiques, CNRS and Aix-Marseille Université, UMR 7257, Polytech Case 925, 13009 Marseille, France
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15
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Wu J, Ye HQ, Zhang QY, Lu G, Zhang B, Gong P. A conformation-based intra-molecular initiation factor identified in the flavivirus RNA-dependent RNA polymerase. PLoS Pathog 2020; 16:e1008484. [PMID: 32357182 PMCID: PMC7219791 DOI: 10.1371/journal.ppat.1008484] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 05/13/2020] [Accepted: 03/18/2020] [Indexed: 12/26/2022] Open
Abstract
The flaviviruses pose serious threats to human health. Being a natural fusion of a methyltransferase (MTase) and an RNA-dependent RNA polymerase (RdRP), NS5 is the most conserved flavivirus protein and an important antiviral target. Previously reported NS5 structures represented by those from the Japanese encephalitis virus (JEV) and Dengue virus serotype 3 (DENV3) exhibit two apparently different global conformations, defining two sets of intra-molecular MTase-RdRP interactions. However, whether these NS5 conformations are conserved in flaviviruses and their specific functions remain elusive. Here we report two forms of DENV serotype 2 (DENV2) NS5 crystal structures representing two conformational states with defined analogies to the JEV-mode and DENV3-mode conformations, respectively, demonstrating the conservation of both conformation modes and providing clues for how different conformational states may be interconnected. Data from in vitro polymerase assays further demonstrate that perturbing the JEV-mode but not the DENV3-mode intra-molecular interactions inhibits catalysis only at initiation, while the cell-based virological analysis suggests that both modes of interactions are important for virus proliferation. Our work highlights the role of MTase as a unique intra-molecular initiation factor specifically only through the JEV-mode conformation, providing an example of conformation-based crosstalk between naturally fused protein functional modules.
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Affiliation(s)
- Jiqin Wu
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, Hubei, China
- University of Chinese Academy of Sciences, Beijing, China
- Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, Hubei, China
| | - Han-Qing Ye
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, Hubei, China
| | - Qiu-Yan Zhang
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, Hubei, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Guoliang Lu
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, Hubei, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Bo Zhang
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, Hubei, China
| | - Peng Gong
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, Hubei, China
- Drug Discovery Center for Infectious Diseases, Nankai University, Tianjin, China
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16
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Bernatchez JA, Coste M, Beck S, Wells GA, Luna LA, Clark AE, Zhu Z, Hecht D, Rich JN, Sohl CD, Purse BW, Siqueira-Neto JL. Activity of Selected Nucleoside Analogue ProTides against Zika Virus in Human Neural Stem Cells. Viruses 2019; 11:v11040365. [PMID: 31010044 PMCID: PMC6521205 DOI: 10.3390/v11040365] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 04/15/2019] [Accepted: 04/18/2019] [Indexed: 01/27/2023] Open
Abstract
Zika virus (ZIKV), an emerging flavivirus that causes neurodevelopmental impairment to fetuses and has been linked to Guillain-Barré syndrome continues to threaten global health due to the absence of targeted prophylaxis or treatment. Nucleoside analogues are good examples of efficient anti-viral inhibitors, and prodrug strategies using phosphate masking groups (ProTides) have been employed to improve the bioavailability of ribonucleoside analogues. Here, we synthesized and tested a small library of 13 ProTides against ZIKV in human neural stem cells. Strong activity was observed for 2′-C-methyluridine and 2′-C-ethynyluridine ProTides with an aryloxyl phosphoramidate masking group. Substitution of a 2-(methylthio) ethyl phosphoramidate for the aryloxyl phosphoramidate ProTide group of 2′-C-methyluridine completely abolished antiviral activity of the compound. The aryloxyl phosphoramidate ProTide of 2′-C-methyluridine outperformed the hepatitis C virus (HCV) drug sofosbuvir in suppression of viral titers and protection from cytopathic effect, while the former compound’s triphosphate active metabolite was better incorporated by purified ZIKV NS5 polymerase over time. These findings suggest both a nucleobase and ProTide group bias for the anti-ZIKV activity of nucleoside analogue ProTides in a disease-relevant cell model.
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Affiliation(s)
- Jean A Bernatchez
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA 92093, USA.
- Center for Discovery and Innovation in Parasitic Diseases, University of California, San Diego, La Jolla, CA 92093, USA.
| | - Michael Coste
- Department of Chemistry and Biochemistry, San Diego State University, San Diego, CA 92182, USA.
| | - Sungjun Beck
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA 92093, USA.
| | - Grace A Wells
- Department of Chemistry and Biochemistry, San Diego State University, San Diego, CA 92182, USA.
| | - Lucas A Luna
- Department of Chemistry and Biochemistry, San Diego State University, San Diego, CA 92182, USA.
| | - Alex E Clark
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA 92093, USA.
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA.
| | - Zhe Zhu
- Sanford Consortium for Regenerative Medicine, La Jolla, CA 92093, USA.
- Department of Medicine, Division of Regenerative Medicine, School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA.
| | - David Hecht
- Department of Chemistry and Biochemistry, San Diego State University, San Diego, CA 92182, USA.
- Department of Chemistry, Southwestern College, Chula Vista, CA 91910, USA.
| | - Jeremy N Rich
- Sanford Consortium for Regenerative Medicine, La Jolla, CA 92093, USA.
- Department of Medicine, Division of Regenerative Medicine, School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA.
| | - Christal D Sohl
- Department of Chemistry and Biochemistry, San Diego State University, San Diego, CA 92182, USA.
| | - Byron W Purse
- Department of Chemistry and Biochemistry, San Diego State University, San Diego, CA 92182, USA.
- The Viral Information Institute, San Diego State University, San Diego, CA 92182, USA.
| | - Jair L Siqueira-Neto
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA 92093, USA.
- Center for Discovery and Innovation in Parasitic Diseases, University of California, San Diego, La Jolla, CA 92093, USA.
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17
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Liu W, Shi X, Gong P. A unique intra-molecular fidelity-modulating mechanism identified in a viral RNA-dependent RNA polymerase. Nucleic Acids Res 2018; 46:10840-10854. [PMID: 30239956 PMCID: PMC6237809 DOI: 10.1093/nar/gky848] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 09/11/2018] [Indexed: 01/07/2023] Open
Abstract
Typically not assisted by proofreading, the RNA-dependent RNA polymerases (RdRPs) encoded by the RNA viruses may need to independently control its fidelity to fulfill virus viability and fitness. However, the precise mechanism by which the RdRP maintains its optimal fidelity level remains largely elusive. By solving 2.1-2.5 Å resolution crystal structures of the classical swine fever virus (CSFV) NS5B, an RdRP with a unique naturally fused N-terminal domain (NTD), we identified high-resolution intra-molecular interactions between the NTD and the RdRP palm domain. In order to dissect possible regulatory functions of NTD, we designed mutations at residues Y471 and E472 to perturb key interactions at the NTD-RdRP interface. When crystallized, some of these NS5B interface mutants maintained the interface, while the others adopted an 'open' conformation that no longer retained the intra-molecular interactions. Data from multiple in vitro RdRP assays indicated that the perturbation of the NTD-RdRP interactions clearly reduced the fidelity level of the RNA synthesis, while the processivity of the NS5B elongation complex was not affected. Collectively, our work demonstrates an explicit and unique mode of polymerase fidelity modulation and provides a vivid example of co-evolution in multi-domain enzymes.
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Affiliation(s)
- Weichi Liu
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei 430071, China,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiaoling Shi
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei 430071, China,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Peng Gong
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei 430071, China,To whom correspondence should be addressed. Tel: +86 27 87197578;
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18
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Harwig A, Landick R, Berkhout B. The Battle of RNA Synthesis: Virus versus Host. Viruses 2017; 9:v9100309. [PMID: 29065472 PMCID: PMC5691660 DOI: 10.3390/v9100309] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 10/19/2017] [Accepted: 10/20/2017] [Indexed: 12/13/2022] Open
Abstract
Transcription control is the foundation of gene regulation. Whereas a cell is fully equipped for this task, viruses often depend on the host to supply tools for their transcription program. Over the course of evolution and adaptation, viruses have found diverse ways to optimally exploit cellular host processes such as transcription to their own benefit. Just as cells are increasingly understood to employ nascent RNAs in transcription regulation, recent discoveries are revealing how viruses use nascent RNAs to benefit their own gene expression. In this review, we first outline the two different transcription programs used by viruses, i.e., transcription (DNA-dependent) and RNA-dependent RNA synthesis. Subsequently, we use the distinct stages (initiation, elongation, termination) to describe the latest insights into nascent RNA-mediated regulation in the context of each relevant stage.
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Affiliation(s)
- Alex Harwig
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA.
| | - Robert Landick
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA.
| | - Ben Berkhout
- Laboratory of Experimental Virology, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands.
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19
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Bessa LM, Launay H, Dujardin M, Cantrelle FX, Lippens G, Landrieu I, Schneider R, Hanoulle X. NMR reveals the intrinsically disordered domain 2 of NS5A protein as an allosteric regulator of the hepatitis C virus RNA polymerase NS5B. J Biol Chem 2017; 292:18024-18043. [PMID: 28912275 DOI: 10.1074/jbc.m117.813766] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 09/06/2017] [Indexed: 12/13/2022] Open
Abstract
Non-structural protein 5B (NS5B) is the RNA-dependent RNA polymerase that catalyzes replication of the hepatitis C virus (HCV) RNA genome and therefore is central for its life cycle. NS5B interacts with the intrinsically disordered domain 2 of NS5A (NS5A-D2), another essential multifunctional HCV protein that is required for RNA replication. As a result, these two proteins represent important targets for anti-HCV chemotherapies. Despite this importance and the existence of NS5B crystal structures, our understanding of the conformational and dynamic behavior of NS5B in solution and its relationship with NS5A-D2 remains incomplete. To address these points, we report the first detailed NMR spectroscopic study of HCV NS5B lacking its membrane anchor (NS5BΔ21). Analysis of constructs with selective isotope labeling of the δ1 methyl groups of isoleucine side chains demonstrates that, in solution, NS5BΔ21 is highly dynamic but predominantly adopts a closed conformation. The addition of NS5A-D2 leads to spectral changes indicative of binding to both allosteric thumb sites I and II of NS5BΔ21 and induces long-range perturbations that affect the RNA-binding properties of the polymerase. We compared these modifications with the short- and long-range effects triggered in NS5BΔ21 upon binding of filibuvir, an allosteric inhibitor. We demonstrate that filibuvir-bound NS5BΔ21 is strongly impaired in the binding of both NS5A-D2 and RNA. NS5A-D2 induces conformational and functional perturbations in NS5B similar to those triggered by filibuvir. Thus, our work highlights NS5A-D2 as an allosteric regulator of the HCV polymerase and provides new insight into the dynamics of NS5B in solution.
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Affiliation(s)
- Luiza M Bessa
- From the University of Lille, CNRS, UMR 8576, UGSF, Unité de Glycobiologie Structurale et Fonctionnelle, 59000 Lille, France
| | - Hélène Launay
- From the University of Lille, CNRS, UMR 8576, UGSF, Unité de Glycobiologie Structurale et Fonctionnelle, 59000 Lille, France
| | - Marie Dujardin
- From the University of Lille, CNRS, UMR 8576, UGSF, Unité de Glycobiologie Structurale et Fonctionnelle, 59000 Lille, France
| | - François-Xavier Cantrelle
- From the University of Lille, CNRS, UMR 8576, UGSF, Unité de Glycobiologie Structurale et Fonctionnelle, 59000 Lille, France
| | - Guy Lippens
- From the University of Lille, CNRS, UMR 8576, UGSF, Unité de Glycobiologie Structurale et Fonctionnelle, 59000 Lille, France
| | - Isabelle Landrieu
- From the University of Lille, CNRS, UMR 8576, UGSF, Unité de Glycobiologie Structurale et Fonctionnelle, 59000 Lille, France
| | - Robert Schneider
- From the University of Lille, CNRS, UMR 8576, UGSF, Unité de Glycobiologie Structurale et Fonctionnelle, 59000 Lille, France
| | - Xavier Hanoulle
- From the University of Lille, CNRS, UMR 8576, UGSF, Unité de Glycobiologie Structurale et Fonctionnelle, 59000 Lille, France
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20
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Rahman MU, Liu H, Wadood A, Chen HF. Allosteric mechanism of cyclopropylindolobenzazepine inhibitors for HCV NS5B RdRp via dynamic correlation network analysis. MOLECULAR BIOSYSTEMS 2017; 12:3280-3293. [PMID: 27528077 DOI: 10.1039/c6mb00521g] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
HCV RNA dependent RNA polymerase (RdRp) nonstructural protein 5B (NS5B) is a major target against hepatitis C virus (HCV) for antiviral therapy. Recently discovered cyclopropylindolobenzazepine derivatives have been considered as the most potent for their ability to bind the thumb site 1 domain and allosterically inhibit HCV NS5B RdRp activity. However, the allosteric mechanism for these derivatives has not been clarified at the molecular level. In this study, fluctuation correlation networks were constructed based on all-atom molecular dynamics simulations to elucidate the allosteric mechanism. The fluctuation correlation networks between free and M2 bound NS5B are significantly different. Information can better transfer from the allosteric site to the catalytic site for bound NS5B than for free NS5B. Thus, the hypothesis of "binding induced allosteric regulation" is proposed to link the enzyme activation and inhibitor binding and then confirmed by the mutant network. Finally, one possible allosteric pathway was identified with the shortest path and evaluated by the perturbation of the network. These methods will be helpful to identify the allosteric pathway of other proteins and to design new drugs targeting the pathway.
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Affiliation(s)
- Mueed Ur Rahman
- State Key Laboratory of Microbial Metabolism, Department of Bioinformatics and Biostatistics, College of Life Sciences and Biotechnology, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai, 200240, China.
| | - Hao Liu
- State Key Laboratory of Microbial Metabolism, Department of Bioinformatics and Biostatistics, College of Life Sciences and Biotechnology, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai, 200240, China.
| | - Abdul Wadood
- Department of Biochemistry, Abdul Wali Khan University Mardan, Mardan-23200, Pakistan.
| | - Hai-Feng Chen
- State Key Laboratory of Microbial Metabolism, Department of Bioinformatics and Biostatistics, College of Life Sciences and Biotechnology, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai, 200240, China. and Shanghai Center for Bioinformation Technology, 1278 Keyuan Road, Shanghai, 200235, China
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21
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Peersen OB. Picornaviral polymerase structure, function, and fidelity modulation. Virus Res 2017; 234:4-20. [PMID: 28163093 PMCID: PMC5476519 DOI: 10.1016/j.virusres.2017.01.026] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 01/27/2017] [Indexed: 12/17/2022]
Abstract
Like all positive strand RNA viruses, the picornaviruses replicate their genomes using a virally encoded RNA-dependent RNA polymerase enzyme known as 3Dpol. Over the past decade we have made tremendous advances in our understanding of 3Dpol structure and function, including the discovery of a novel mechanism for closing the active site that allows these viruses to easily fine tune replication fidelity and quasispecies distributions. This review summarizes current knowledge of picornaviral polymerase structure and how the enzyme interacts with RNA and other viral proteins to form stable and processive elongation complexes. The picornaviral RdRPs are among the smallest viral polymerases, but their fundamental molecular mechanism for catalysis appears to be generally applicable as a common feature of all positive strand RNA virus polymerases.
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Affiliation(s)
- Olve B Peersen
- Department of Biochemistry & Molecular Biology, Colorado State University, Fort Collins, CO 80523-1870, United States.
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22
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Abstract
Hepatitis C, caused by the hepatitis C virus (HCV) that attacks the liver and leads to inflammation, is a severe threat to human health. Pegylated interferon α (INF-α) and ribavirin based therapy was once the standard therapy for HCV infection. However, it is suboptimal in efficacy and poorly tolerated in some patients. In the last five years, four classes of direct antiviral drugs (NAAs) that target non-structural proteins (NS) of the virus including NS3/NS4A, NS5A, and NS5B have been developed and opened a new era in HCV treatment as they are more effective and tolerable than the INF-α and ribavirin combination regimen. Importantly, the newly introduced multiple NAAs combination therapy makes it possible to eradicate all genotypes of HCV. We review recent progress on the research and development of DAAs in the present article.
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Affiliation(s)
- Jianjun Gao
- Department of Pharmacology, Qingdao University School of Pharmacy
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23
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Alphonse S, Ghose R. Cystoviral RNA-directed RNA polymerases: Regulation of RNA synthesis on multiple time and length scales. Virus Res 2017; 234:135-152. [PMID: 28104452 PMCID: PMC5476504 DOI: 10.1016/j.virusres.2017.01.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Revised: 01/04/2017] [Accepted: 01/09/2017] [Indexed: 12/18/2022]
Abstract
Role of the RNA polymerase in the cystoviral life-cycle. Spatio-temporal regulation of RNA synthesis in cystoviruses. Emerging role of conformational dynamics in polymerase function.
P2, an RNA-directed RNA polymerase (RdRP), is encoded on the largest of the three segments of the double-stranded RNA genome of cystoviruses. P2 performs the dual tasks of replication and transcription de novo on single-stranded RNA templates, and plays a critical role in the viral life-cycle. Work over the last few decades has yielded a wealth of biochemical and structural information on the functional regulation of P2, on its role in the spatiotemporal regulation of RNA synthesis and its variability across the Cystoviridae family. These range from atomic resolution snapshots of P2 trapped in functionally significant states, in complex with catalytic/structural metal ions, polynucleotide templates and substrate nucleoside triphosphates, to P2 in the context of viral capsids providing structural insight into the assembly of supramolecular complexes and regulatory interactions therein. They include in vitro biochemical studies using P2 purified to homogeneity and in vivo studies utilizing infectious core particles. Recent advances in experimental techniques have also allowed access to the temporal dimension and enabled the characterization of dynamics of P2 on the sub-nanosecond to millisecond timescale through measurements of nuclear spin relaxation in solution and single molecule studies of transcription from seconds to minutes. Below we summarize the most significant results that provide critical insight into the role of P2 in regulating RNA synthesis in cystoviruses.
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Affiliation(s)
- Sébastien Alphonse
- Department of Chemistry and Biochemistry, The City College of New York, New York, NY 10031, United States.
| | - Ranajeet Ghose
- Department of Chemistry and Biochemistry, The City College of New York, New York, NY 10031, United States; Graduate Programs in Biochemistry, The Graduate Center of CUNY, New York, NY 10016, United States; Graduate Programs in Chemistry, The Graduate Center of CUNY, New York, NY 10016, United States; Graduate Programs in Physics, The Graduate Center of CUNY, New York, NY 10016, United States.
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24
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Potisopon S, Ferron F, Fattorini V, Selisko B, Canard B. Substrate selectivity of Dengue and Zika virus NS5 polymerase towards 2'-modified nucleotide analogues. Antiviral Res 2016; 140:25-36. [PMID: 28041959 DOI: 10.1016/j.antiviral.2016.12.021] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 12/28/2016] [Accepted: 12/29/2016] [Indexed: 12/11/2022]
Abstract
In targeting the essential viral RNA-dependent RNA-polymerase (RdRp), nucleotide analogues play a major role in antiviral therapies. In the Flaviviridae family, the hepatitis C virus (HCV) can be eradicated from chronically infected patients using a combination of drugs which generally include the 2'-modified uridine analogue Sofosbuvir, delivered as nucleotide prodrug. Dengue and Zika viruses are emerging flaviviruses whose RdRp is closely related to that of HCV, yet no nucleoside drug has been clinically approved for these acute infections. We have purified dengue and Zika virus full-length NS5, the viral RdRps, and used them to assemble a stable binary complex made of NS5 and virus-specific RNA primer/templates. The complex was used to assess the selectivity of NS5 towards nucleotide analogues bearing modifications at the 2'-position. We show that dengue and Zika virus RdRps exhibit the same discrimination pattern: 2'-O-Me > 2'-C-Me-2'-F > 2'-C-Me nucleoside analogues, unlike HCV RdRp for which the presence of the 2'-F is beneficial rendering the discrimination pattern 2'-O-Me > 2'-C-Me ≥ 2'-C-Me-2'-F. Both 2'-C-Me and 2'-C-Me-2'-F analogues act as non-obligate RNA chain terminators. The dengue and Zika NS5 nucleotide selectivity towards 2'-modified NTPs mirrors potency of the corresponding analogues in infected cell cultures.
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Affiliation(s)
- Supanee Potisopon
- Aix-Marseille Université, AFMB (Laboratoire d'Architecture et Fonction de Macromolécules Biologiques) UMR 7257, 163 Avenue de Luminy, 13288 Marseille, France; CNRS, AFMB UMR 7257, 163 Avenue de Luminy, 13288 Marseille, France
| | - François Ferron
- Aix-Marseille Université, AFMB (Laboratoire d'Architecture et Fonction de Macromolécules Biologiques) UMR 7257, 163 Avenue de Luminy, 13288 Marseille, France; CNRS, AFMB UMR 7257, 163 Avenue de Luminy, 13288 Marseille, France
| | - Véronique Fattorini
- Aix-Marseille Université, AFMB (Laboratoire d'Architecture et Fonction de Macromolécules Biologiques) UMR 7257, 163 Avenue de Luminy, 13288 Marseille, France; CNRS, AFMB UMR 7257, 163 Avenue de Luminy, 13288 Marseille, France
| | - Barbara Selisko
- Aix-Marseille Université, AFMB (Laboratoire d'Architecture et Fonction de Macromolécules Biologiques) UMR 7257, 163 Avenue de Luminy, 13288 Marseille, France; CNRS, AFMB UMR 7257, 163 Avenue de Luminy, 13288 Marseille, France.
| | - Bruno Canard
- Aix-Marseille Université, AFMB (Laboratoire d'Architecture et Fonction de Macromolécules Biologiques) UMR 7257, 163 Avenue de Luminy, 13288 Marseille, France; CNRS, AFMB UMR 7257, 163 Avenue de Luminy, 13288 Marseille, France.
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25
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Miyamura T, Lemon SM, Walker CM, Wakita T. The HCV Replicase Complex and Viral RNA Synthesis. HEPATITIS C VIRUS I 2016. [PMCID: PMC7122888 DOI: 10.1007/978-4-431-56098-2_8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Replication of hepatitis C virus (HCV) is tightly linked to membrane alterations designated the membranous web, harboring the viral replicase complex. In this chapter we describe the morphology and 3D architecture of the HCV-induced replication organelles, mainly consisting of double membrane vesicles, which are generated by a concerted action of the nonstructural proteins NS3 to NS5B. Recent studies have furthermore identified a number of host cell proteins and lipids contributing to the biogenesis of the membranous web, which are discussed in this chapter. Viral RNA synthesis is tightly associated with these membrane alterations and mainly driven by the viral RNA dependent RNA polymerase NS5B. We summarize our current knowledge of the structure and function of NS5B, the role of cis-acting replication elements at the termini of the genome in regulating RNA synthesis and the contribution of additional viral and host factors to viral RNA synthesis, which is still ill defined.
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Affiliation(s)
- Tatsuo Miyamura
- National Institute of Infectious Diseases, Tokyo, Tokyo Japan
| | - Stanley M. Lemon
- Departments of Medicine and Microbiology & Immunology , The University of North Carolina, Chapel Hill, North Carolina USA
| | - Christopher M. Walker
- Center for Vaccines and Immunity, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio USA
| | - Takaji Wakita
- National Institute of Infectious Diseases, Tokyo, Tokyo Japan
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26
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Abstract
Extracting kinetic parameters from DNA polymerase-catalyzed processive polymerization data using traditional initial-rate analysis has proven to be problematic for multiple reasons. The first substrate, DNA template, is a heterogeneous polymer and binds tightly to DNA polymerase. Further, the affinity and speed of incorporation of the second substrate, deoxynucleoside triphosphate (dNTP), vary greatly depending on the nature of the templating base and surrounding sequence. Here, we present a mathematical model consisting of the DNA template-binding step and a Michaelis-Menten-type nucleotide incorporation step acting on a DNA template with a finite length. The model was numerically integrated and globally fitted to experimental reaction time courses. The time courses were determined by monitoring the processive synthesis of oligonucleotides of lengths between 50 and 120 nucleotides by DNA polymerase I (Klenow fragment exo-) using the fluorophore PicoGreen. For processive polymerization, we were able to estimate an enzyme-template association rate k1 of 7.4 μM-1 s-1, a disassociation rate k-1 of 0.07 s-1, and a Kd of 10 nM, and the steady-state parameters for correct dNTP incorporation give kcat values of 2.5-3.3 s-1 and Km values of 0.51-0.86 μM. From the analysis of time courses measured between 5 and 25 °C, an activation energy for kcat of 82 kJ mol-1 was calculated, and it was found that up to 73% of Klenow fragment becomes inactivated or involved in unproductive binding at lower temperatures. Finally, a solvent deuterium kinetic isotope effect (KIE) of 3.0-3.2 was observed under processive synthesis conditions, which suggests that either the intrinsic KIE is unusually high, at least 30-40, or previous findings, showing that the phosphoryl transfer step occurs rapidly and is flanked by two slow conformational changes, need to be re-evaluated. We suggest that the numerical integration of rate equations provides a high level of flexibility and generally produces superior results compared to those of initial-rate analysis in the study of DNA polymerase kinetics and, by extension, other complex enzyme systems.
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Affiliation(s)
- Julius Rentergent
- Manchester Institute of Biotechnology, University of Manchester , Manchester M1 7DN, U.K
| | - Max D Driscoll
- Manchester Institute of Biotechnology, University of Manchester , Manchester M1 7DN, U.K
| | - Sam Hay
- Manchester Institute of Biotechnology, University of Manchester , Manchester M1 7DN, U.K
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27
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Biochemical Characterization of the Active Anti-Hepatitis C Virus Metabolites of 2,6-Diaminopurine Ribonucleoside Prodrug Compared to Sofosbuvir and BMS-986094. Antimicrob Agents Chemother 2016; 60:4659-69. [PMID: 27216050 DOI: 10.1128/aac.00318-16] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 05/12/2016] [Indexed: 12/20/2022] Open
Abstract
Ribonucleoside analog inhibitors (rNAI) target the hepatitis C virus (HCV) RNA-dependent RNA polymerase nonstructural protein 5B (NS5B) and cause RNA chain termination. Here, we expand our studies on β-d-2'-C-methyl-2,6-diaminopurine-ribonucleotide (DAPN) phosphoramidate prodrug 1 (PD1) as a novel investigational inhibitor of HCV. DAPN-PD1 is metabolized intracellularly into two distinct bioactive nucleoside triphosphate (TP) analogs. The first metabolite, 2'-C-methyl-GTP, is a well-characterized inhibitor of NS5B polymerase, whereas the second metabolite, 2'-C-methyl-DAPN-TP, behaves as an adenosine base analog. In vitro assays suggest that both metabolites are inhibitors of NS5B-mediated RNA polymerization. Additional factors, such as rNAI-TP incorporation efficiencies, intracellular rNAI-TP levels, and competition with natural ribonucleotides, were examined in order to further characterize the potential role of each nucleotide metabolite in vivo Finally, we found that although both 2'-C-methyl-GTP and 2'-C-methyl-DAPN-TP were weak substrates for human mitochondrial RNA (mtRNA) polymerase (POLRMT) in vitro, DAPN-PD1 did not cause off-target inhibition of mtRNA transcription in Huh-7 cells. In contrast, administration of BMS-986094, which also generates 2'-C-methyl-GTP and previously has been associated with toxicity in humans, caused detectable inhibition of mtRNA transcription. Metabolism of BMS-986094 in Huh-7 cells leads to 87-fold higher levels of intracellular 2'-C-methyl-GTP than DAPN-PD1. Collectively, our data characterize DAPN-PD1 as a novel and potent antiviral agent that combines the delivery of two active metabolites.
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28
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Deredge D, Li J, Johnson KA, Wintrode PL. Hydrogen/Deuterium Exchange Kinetics Demonstrate Long Range Allosteric Effects of Thumb Site 2 Inhibitors of Hepatitis C Viral RNA-dependent RNA Polymerase. J Biol Chem 2016; 291:10078-88. [PMID: 27006396 DOI: 10.1074/jbc.m115.708370] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Indexed: 01/08/2023] Open
Abstract
New nonnucleoside analogs are being developed as part of a multi-drug regimen to treat hepatitis C viral infections. Particularly promising are inhibitors that bind to the surface of the thumb domain of the viral RNA-dependent RNA polymerase (NS5B). Numerous crystal structures have been solved showing small molecule non-nucleoside inhibitors bound to the hepatitis C viral polymerase, but these structures alone do not define the mechanism of inhibition. Our prior kinetic analysis showed that nonnucleoside inhibitors binding to thumb site-2 (NNI2) do not block initiation or elongation of RNA synthesis; rather, they block the transition from the initiation to elongation, which is thought to proceed with significant structural rearrangement of the enzyme-RNA complex. Here we have mapped the effect of three NNI2 inhibitors on the conformational dynamics of the enzyme using hydrogen/deuterium exchange kinetics. All three inhibitors rigidify an extensive allosteric network extending >40 Å from the binding site, thus providing a structural rationale for the observed disruption of the transition from distributive initiation to processive elongation. The two more potent inhibitors also suppress slow cooperative unfolding in the fingers extension-thumb interface and primer grip, which may contribute their stronger inhibition. These results establish that NNI2 inhibitors act through long range allosteric effects, reveal important conformational changes underlying normal polymerase function, and point the way to the design of more effective allosteric inhibitors that exploit this new information.
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Affiliation(s)
- Daniel Deredge
- From the Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland 21201 and
| | - Jiawen Li
- Department of Molecular Biosciences, Institute for Cell and Molecular Biology, University of Texas, Austin, Texas 78712
| | - Kenneth A Johnson
- Department of Molecular Biosciences, Institute for Cell and Molecular Biology, University of Texas, Austin, Texas 78712
| | - Patrick L Wintrode
- From the Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland 21201 and
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29
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Yang L, Jiang C, Hu S, Diao Q, Li J, Si W, Chen M, Zhao RY. Evolving Diversity of Hepatitis C Viruses in Yunnan Honghe, China. Int J Mol Sci 2016; 17:403. [PMID: 26999127 PMCID: PMC4813258 DOI: 10.3390/ijms17030403] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Revised: 02/26/2016] [Accepted: 03/09/2016] [Indexed: 12/23/2022] Open
Abstract
The Chinese Honghe Autonomous Prefecture (Honghe) in Yunnan Province is a unique ethnic area because it is inhabited by more than ten different minority ethnic groups. Geographically, Honghe directly shares a border with Vietnam. The objective of this study was to investigate genetic diversity and distribution of the Hepatitis C virus (HCV) in Honghe. Ninety nine subjects who were infected with HCV or HCV/HIV (Human Immunodeficiency Virus Type 1) were recruited into this study. HCV genotypes and subtypes were determined based on the sequences of the core/envelope 1 (C/E1) and the nonstructural protein 5B (NS5B) genomic regions. The viral diversity and origins of dissemination were examined by phylogenetic analyses. Three HCV genotypes (1, 3 and 6) with six subtypes (1b, 3b, 3a, 6a, 6n and 6v) were identified. The most predominant form was genotype 3 (54.6%) followed by 6 (34.3%), and 1 (9.1%). The HCV subtype 3b appeared to be the most frequent form (38.4%) followed by 6n (20.2%) and 3a (16.2%). Statistical analyses suggested a possible rise of the genotype 6a in Honghe among intravenous drug users with HCV/HIV co-infections. Further phylogenetic analyses suggested that similar HCV-6a viruses might have been circulating in the Honghe area for more than a decade, which likely originated from Vietnam or vice versa. Two HCV samples with single HCV infection (SC34 and SC45) were isolated that could represent new recombinant variants. Although the genetic prevalence of HCV in Honghe is in general agreement with that of Southwest China and Yunnan Province, the diversity of HCV genotypes and subtypes in Honghe is somewhat unique and evolving. Information presented here should provide useful information for future health surveillance and prevention of HCV infection in this area.
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Affiliation(s)
- Lanhui Yang
- Department of Clinical Laboratory, The First People's Hospital of Honghe, Mengzi 661100, China.
- Division of Molecular Pathology, Department of Pathology, University of Maryland School of Medicine, Baltimore, 21201 MD, USA.
| | - Chenyan Jiang
- Division of Life Science, College of Life Science and Technology, Honghe University, Mengzi 661100, China.
| | - Song Hu
- Department of Infectious Diseases, The First People's Hospital of Honghe, Mengzi 661100, China.
| | - Qiongni Diao
- Division of Life Science, College of Life Science and Technology, Honghe University, Mengzi 661100, China.
| | - Jia Li
- Department of Infectious Diseases, The First People's Hospital of Honghe, Mengzi 661100, China.
| | - Wei Si
- Department of Clinical Laboratory, The First People's Hospital of Honghe, Mengzi 661100, China.
| | - Mei Chen
- Department of Infectious Diseases, The First People's Hospital of Honghe, Mengzi 661100, China.
| | - Richard Y Zhao
- Division of Molecular Pathology, Department of Pathology, University of Maryland School of Medicine, Baltimore, 21201 MD, USA.
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30
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Li J, Johnson KA. Thumb Site 2 Inhibitors of Hepatitis C Viral RNA-dependent RNA Polymerase Allosterically Block the Transition from Initiation to Elongation. J Biol Chem 2016; 291:10067-77. [PMID: 26851276 DOI: 10.1074/jbc.m115.708354] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Indexed: 01/12/2023] Open
Abstract
Replication of the hepatitis C viral genome is catalyzed by the NS5B (nonstructural protein 5B) RNA-dependent RNA polymerase, which is a major target of antiviral drugs currently in the clinic. Prior studies established that initiation of RNA replication could be facilitated by starting with a dinucleotide (pGG). Here we establish conditions for efficient initiation from GTP to form the dinucleotide and subsequent intermediates leading to highly processive elongation, and we examined the effects of four classes of nonnucleoside inhibitors on each step of the reaction. We show that palm site inhibitors block initiation starting from GTP but not when starting from pGG. In addition we show that nonnucleoside inhibitors binding to thumb site-2 (NNI2) lead to the accumulation of abortive intermediates three-five nucleotides in length. Our kinetic analysis shows that NNI2 do not significantly block initiation or elongation of RNA synthesis; rather, they block the transition from initiation to elongation, which is thought to proceed with significant structural rearrangement of the enzyme-RNA complex including displacement of the β-loop from the active site. Direct measurement in single turnover kinetic studies show that pyrophosphate release is faster than the chemistry step, which appears to be rate-limiting during processive synthesis. These results reveal important new details to define the steps involved in initiation and elongation during viral RNA replication, establish the allosteric mechanisms by which NNI2 inhibitors act, and point the way to the design of more effective allosteric inhibitors that exploit this new information.
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Affiliation(s)
- Jiawen Li
- From the Department of Molecular Biosciences, Institute for Cell and Molecular Biology, University of Texas at Austin, Austin, Texas 78712
| | - Kenneth A Johnson
- From the Department of Molecular Biosciences, Institute for Cell and Molecular Biology, University of Texas at Austin, Austin, Texas 78712
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31
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Biochemical Evaluation of the Inhibition Properties of Favipiravir and 2'-C-Methyl-Cytidine Triphosphates against Human and Mouse Norovirus RNA Polymerases. Antimicrob Agents Chemother 2015; 59:7504-16. [PMID: 26392512 DOI: 10.1128/aac.01391-15] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 09/14/2015] [Indexed: 11/20/2022] Open
Abstract
Norovirus (NoV) is a positive-sense single-stranded RNA virus that causes acute gastroenteritis and is responsible for 200,000 deaths per year worldwide. No effective vaccine or treatment is available. Recent studies have shown that the nucleoside analogs favipiravir (T-705) and 2'-C-methyl-cytidine (2CM-C) inhibit NoV replication in vitro and in animal models, but their precise mechanism of action is unknown. We evaluated the molecular interactions between nucleoside triphosphates and NoV RNA-dependent RNA polymerase (NoVpol), the enzyme responsible for replication and transcription of NoV genomic RNA. We found that T-705 ribonucleoside triphosphate (RTP) and 2CM-C triphosphate (2CM-CTP) equally inhibited human and mouse NoVpol activities at concentrations resulting in 50% of maximum inhibition (IC50s) in the low micromolar range. 2CM-CTP inhibited the viral polymerases by competing directly with natural CTP during primer elongation, whereas T-705 RTP competed mostly with ATP and GTP at the initiation and elongation steps. Incorporation of 2CM-CTP into viral RNA blocked subsequent RNA synthesis, whereas T-705 RTP did not cause immediate chain termination of NoVpol. 2CM-CTP and T-705 RTP displayed low levels of enzyme selectivity, as they were both recognized as substrates by human mitochondrial RNA polymerase. The level of discrimination by the human enzyme was increased with a novel analog of T-705 RTP containing a 2'-C-methyl substitution. Collectively, our data suggest that 2CM-C inhibits replication of NoV by acting as a classic chain terminator, while T-705 may inhibit the virus by multiple mechanisms of action. Understanding the precise mechanism of action of anti-NoV compounds could provide a rational basis for optimizing their inhibition potencies and selectivities.
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32
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Dulin D, Vilfan ID, Berghuis BA, Hage S, Bamford DH, Poranen MM, Depken M, Dekker NH. Elongation-Competent Pauses Govern the Fidelity of a Viral RNA-Dependent RNA Polymerase. Cell Rep 2015; 10:983-992. [PMID: 25683720 DOI: 10.1016/j.celrep.2015.01.031] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 12/23/2014] [Accepted: 01/10/2015] [Indexed: 02/06/2023] Open
Abstract
RNA viruses have specific mutation rates that balance the conflicting needs of an evolutionary response to host antiviral defenses and avoidance of the error catastrophe. While most mutations are known to originate in replication errors, difficulties of capturing the underlying dynamics have left the mechanochemical basis of viral mutagenesis unresolved. Here, we use multiplexed magnetic tweezers to investigate error incorporation by the bacteriophage Φ6 RNA-dependent RNA polymerase. We extract large datasets fingerprinting real-time polymerase dynamics over four magnitudes in time, in the presence of nucleotide analogs, and under varying NTP and divalent cation concentrations and fork stability. Quantitative analysis reveals a new pause state that modulates polymerase fidelity and so ties viral polymerase pausing to the biological function of optimizing virulence. Adjusting the frequency of such pauses offers a target for therapeutics and may also reflect an evolutionary strategy for virus populations to track the gradual evolution of their hosts.
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Affiliation(s)
- David Dulin
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, the Netherlands
| | - Igor D Vilfan
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, the Netherlands
| | - Bojk A Berghuis
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, the Netherlands
| | - Susanne Hage
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, the Netherlands
| | - Dennis H Bamford
- Department of Biosciences, University of Helsinki, Viikki Biocenter 2, P.O. Box 56 (Viikinkaari 5), 00014 Helsinki, Finland; Institute of Biotechnology, University of Helsinki, Viikki Biocenter 2, P.O. Box 56 (Viikinkaari 5), 00014 Helsinki, Finland
| | - Minna M Poranen
- Department of Biosciences, University of Helsinki, Viikki Biocenter 2, P.O. Box 56 (Viikinkaari 5), 00014 Helsinki, Finland.
| | - Martin Depken
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, the Netherlands.
| | - Nynke H Dekker
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, the Netherlands.
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33
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Hydrophobic and charged residues in the C-terminal arm of hepatitis C virus RNA-dependent RNA polymerase regulate initiation and elongation. J Virol 2014; 89:2052-63. [PMID: 25428878 DOI: 10.1128/jvi.01106-14] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
UNLABELLED The RNA-dependent RNA polymerase (RdRp) of hepatitis C virus (HCV) is essential for viral genome replication. Crystal structures of the HCV RdRp reveal two C-terminal features, a β-loop and a C-terminal arm, suitably located for involvement in positioning components of the initiation complex. Here we show that these two elements intimately regulate template and nucleotide binding, initiation, and elongation. We constructed a series of β-loop and C-terminal arm mutants, which were used for in vitro analysis of RdRp de novo initiation and primer extension activities. All mutants showed a substantial decrease in initiation activities but a marked increase in primer extension activities, indicating an ability to form more stable elongation complexes with long primer-template RNAs. Structural studies of the mutants indicated that these enzyme properties might be attributed to an increased flexibility in the C-terminal features resulting in a more open polymerase cleft, which likely favors the elongation process but hampers the initiation steps. A UTP cocrystal structure of one mutant shows, in contrast to the wild-type protein, several alternate conformations of the substrate, confirming that even subtle changes in the C-terminal arm result in a more loosely organized active site and flexible binding modes of the nucleotide. We used a subgenomic replicon system to assess the effects of the same mutations on viral replication in cells. Even the subtlest mutations either severely impaired or completely abolished the ability of the replicon to replicate, further supporting the concept that the correct positioning of both the β-loop and C-terminal arm plays an essential role during initiation and in HCV replication in general. IMPORTANCE HCV RNA polymerase is a key target for the development of directly acting agents to cure HCV infections, which necessitates a thorough understanding of the functional roles of the various structural features of the RdRp. Here we show that even highly conservative changes, e.g., Tyr→Phe or Asp→Glu, in these seemingly peripheral structural features have profound effects on the initiation and elongation properties of the HCV polymerase.
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34
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Reich S, Kovermann M, Lilie H, Knick P, Geissler R, Golbik RP, Balbach J, Behrens SE. Initiation of RNA synthesis by the hepatitis C virus RNA-dependent RNA polymerase is affected by the structure of the RNA template. Biochemistry 2014; 53:7002-12. [PMID: 25310724 PMCID: PMC4230328 DOI: 10.1021/bi5006656] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
![]()
The
hepatitis C virus (HCV) RNA-dependent RNA polymerase NS5B is
a central enzyme of the intracellular replication of the viral (+)RNA
genome. Here, we studied the individual steps of NS5B-catalyzed RNA
synthesis by a combination of biophysical methods, including real-time
1D 1H NMR spectroscopy. NS5B was found to bind to a nonstructured
and a structured RNA template in different modes. Following NTP binding
and conversion to the catalysis-competent ternary complex, the polymerase
revealed an improved affinity for the template. By monitoring the
folding/unfolding of 3′(−)SL by 1H NMR, the
base pair at the stem’s edge was identified as the most stable
component of the structure. 1H NMR real-time analysis of
NS5B-catalyzed RNA synthesis on 3′(−)SL showed that
a pronounced lag phase preceded the processive polymerization reaction.
The presence of the double-stranded stem with the edge base pair acting
as the main energy barrier impaired RNA synthesis catalyzed by NS5B.
Our observations suggest a crucial role of RNA-modulating factors
in the HCV replication process.
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Affiliation(s)
- Stefan Reich
- Institute of Biochemistry and Biotechnology, Section of Microbial Biotechnology, ‡Institute of Physics, Section of Biophysics, §Institute of Biochemistry and Biotechnology, Section of Technical Biochemistry, Martin Luther University Halle-Wittenberg , D-06120 Halle/Saale, Germany
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35
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Perturbation in the conserved methyltransferase-polymerase interface of flavivirus NS5 differentially affects polymerase initiation and elongation. J Virol 2014; 89:249-61. [PMID: 25320292 DOI: 10.1128/jvi.02085-14] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
UNLABELLED The flavivirus NS5 is a natural fusion of a methyltransferase (MTase) and an RNA-dependent RNA polymerase (RdRP). Analogous to DNA-dependent RNA polymerases, the NS5 polymerase initiates RNA synthesis through a de novo mechanism and then makes a transition to a processive elongation phase. However, whether and how the MTase affects polymerase activities through intramolecular interactions remain elusive. By solving the crystal structure of the Japanese encephalitis virus (JEV) NS5, we recently identified an MTase-RdRP interface containing a set of six hydrophobic residues highly conserved among flaviviruses. To dissect the functional relevance of this interface, we made a series of JEV NS5 constructs with mutations of these hydrophobic residues and/or with the N-terminal first 261 residues and other residues up to the first 303 residues deleted. Compared to the wild-type (WT) NS5, full-length NS5 variants exhibited consistent up- or downregulation of the initiation activities in two types of polymerase assays. Five representative full-length NS5 constructs were then tested in an elongation assay, from which the apparent single-nucleotide incorporation rate constant was estimated. Interestingly, two constructs exhibited different elongation kinetics from the WT NS5, with an effect rather opposite to what was observed at initiation. Moreover, constructs with MTase and/or the linker region (residues 266 to 275) removed still retained polymerase activities, albeit at overall lower levels. However, further removal of the N-terminal extension (residues 276 to 303) abolished regular template-directed synthesis. Together, our data showed that the MTase-RdRP interface is relevant in both polymerase initiation and elongation, likely with different regulation mechanisms in these two major phases of RNA synthesis. IMPORTANCE The flavivirus NS5 is very unique in having a methyltransferase (MTase) placed on the immediate N terminus of its RNA-dependent RNA polymerase (RdRP). We recently solved the crystal structure of the full-length NS5, which revealed a conserved interface between MTase and RdRP. Building on this discovery, here we carried out in vitro polymerase assays to address the functional relevance of the interface interactions. By explicitly probing polymerase initiation and elongation activities, we found that perturbation in the MTase-RdRP interface had different impacts on different phases of synthesis, suggesting that the roles and contribution of the interface interactions may change upon phase transitions. By comparing the N-terminal-truncated enzymes with the full-length NS5, we collected data to indicate the indispensability to regular polymerase activities of a region that was functionally unclarified previously. Taken together, we provide biochemical evidence and mechanistic insights for the cross talk between the two enzyme modules of flavivirus NS5.
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36
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Deval J, Symons JA, Beigelman L. Inhibition of viral RNA polymerases by nucleoside and nucleotide analogs: therapeutic applications against positive-strand RNA viruses beyond hepatitis C virus. Curr Opin Virol 2014; 9:1-7. [PMID: 25194816 PMCID: PMC7102778 DOI: 10.1016/j.coviro.2014.08.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 08/19/2014] [Accepted: 08/20/2014] [Indexed: 12/21/2022]
Abstract
New therapies for infections caused by positive-strand RNA viruses are needed. Novel nucleoside and nucleotide analogs that inhibit HCV have been developed. Some of these molecules also inhibit other positive-strand RNA viruses. Optimization of antiviral potency and/or target delivery is necessary.
A number of important human infections are caused by positive-strand RNA viruses, yet almost none can be treated with small molecule antiviral therapeutics. One exception is the chronic infection caused by hepatitis C virus (HCV), against which new generations of potent inhibitors are being developed. One of the main molecular targets for anti-HCV drugs is the viral RNA-dependent RNA polymerase, NS5B. This review summarizes the search for nucleoside and nucleotide analogs that inhibit HCV NS5B, which led to the FDA approval of sofosbuvir in 2013. Advances in anti-HCV therapeutics have also stimulated efforts to develop nucleoside analogs against other positive-strand RNA viruses. Although it remains to be validated in the clinic, the prospect of using nucleoside analogs to treat acute infections caused by RNA viruses represents an important paradigm shift and a new frontier for future antiviral therapies.
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Affiliation(s)
- Jerome Deval
- Alios BioPharma, Inc., 260 East Grand Avenue, South San Francisco, CA 94080, USA.
| | - Julian A Symons
- Alios BioPharma, Inc., 260 East Grand Avenue, South San Francisco, CA 94080, USA
| | - Leo Beigelman
- Alios BioPharma, Inc., 260 East Grand Avenue, South San Francisco, CA 94080, USA.
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Subissi L, Decroly E, Selisko B, Canard B, Imbert I. A closed-handed affair: positive-strand RNA virus polymerases. Future Virol 2014. [DOI: 10.2217/fvl.14.53] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
ABSTRACT RNA viruses are important emerging pathogens that cause human and animal infectious diseases. Antiviral therapies have to deal with the high mutational capacity of RNA viruses, which quickly adapt to new environments. A primary target for antiviral drug development is the viral RNA-dependent RNA polymerase (RdRp), which is the central enzyme of the viral RNA replication/transcription machinery. Here, we review the current mechanistic and structural knowledge on RdRps of positive-strand RNA viruses gained through crystallography and biochemistry. In addition, we review the growing body of information on RdRp-mediated strategies, such as proofreading and genome end repair, used by positive-strand RNA viruses to maintain their genome integrity.
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Affiliation(s)
- Lorenzo Subissi
- Centre National de la Recherche Scientifique, Aix-Marseille Université, CNRS UMR 7257, AFMB, 163 Avenue de Luminy, 13288 Marseille, France
| | - Etienne Decroly
- Centre National de la Recherche Scientifique, Aix-Marseille Université, CNRS UMR 7257, AFMB, 163 Avenue de Luminy, 13288 Marseille, France
| | - Barbara Selisko
- Centre National de la Recherche Scientifique, Aix-Marseille Université, CNRS UMR 7257, AFMB, 163 Avenue de Luminy, 13288 Marseille, France
| | - Bruno Canard
- Centre National de la Recherche Scientifique, Aix-Marseille Université, CNRS UMR 7257, AFMB, 163 Avenue de Luminy, 13288 Marseille, France
| | - Isabelle Imbert
- Centre National de la Recherche Scientifique, Aix-Marseille Université, CNRS UMR 7257, AFMB, 163 Avenue de Luminy, 13288 Marseille, France
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Efficiency of incorporation and chain termination determines the inhibition potency of 2'-modified nucleotide analogs against hepatitis C virus polymerase. Antimicrob Agents Chemother 2014; 58:3636-45. [PMID: 24733478 DOI: 10.1128/aac.02666-14] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Ribonucleotide analog inhibitors of the RNA-dependent RNA polymerase of hepatitis C virus (HCV) represent one of the most exciting recent developments in HCV antiviral therapy. Although it is well established that these molecules cause chain termination by competing at the triphosphate level with natural nucleotides for incorporation into elongating RNA, strategies to rationally optimize antiviral potency based on enzyme kinetics remain elusive. In this study, we used the isolated HCV polymerase elongation complex to determine the pre-steady-state kinetics of incorporation of 2'F-2'C-Me-UTP, the active metabolite of the anti-HCV drug sofosbuvir. 2'F-2'C-Me-UTP was efficiently incorporated by HCV polymerase with apparent Kd (equilibrium constant) and kpol (rate of nucleotide incorporation at saturating nucleotide concentration) values of 113 ± 28 μM and 0.67 ± 0.05 s(-1), respectively, giving an overall substrate efficiency (kpol/Kd) of 0.0059 ± 0.0015 μM(-1) s(-1). We also measured the substrate efficiency of other UTP analogs and found that substitutions at the 2' position on the ribose can greatly affect their level of incorporation, with a rank order of OH > F > NH2 > F-C-Me > C-Me > N3 > ara. However, the efficiency of chain termination following the incorporation of UMP analogs followed a different order, with only 2'F-2'C-Me-, 2'C-Me-, and 2'ara-UTP causing complete and immediate chain termination. The chain termination profile of the 2'-modified nucleotides explains the apparent lack of correlation observed across all molecules between substrate efficiency at the single-nucleotide level and their overall inhibition potency. To our knowledge, these results provide the first attempt to use pre-steady-state kinetics to uncover the mechanism of action of 2'-modified NTP analogs against HCV polymerase.
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Boyce SE, Tirunagari N, Niedziela-Majka A, Perry J, Wong M, Kan E, Lagpacan L, Barauskas O, Hung M, Fenaux M, Appleby T, Watkins WJ, Schmitz U, Sakowicz R. Structural and regulatory elements of HCV NS5B polymerase--β-loop and C-terminal tail--are required for activity of allosteric thumb site II inhibitors. PLoS One 2014; 9:e84808. [PMID: 24416288 PMCID: PMC3886995 DOI: 10.1371/journal.pone.0084808] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 11/19/2013] [Indexed: 01/01/2023] Open
Abstract
Elucidation of the mechanism of action of the HCV NS5B polymerase thumb site II inhibitors has presented a challenge. Current opinion holds that these allosteric inhibitors stabilize the closed, inactive enzyme conformation, but how this inhibition is accomplished mechanistically is not well understood. Here, using a panel of NS5B proteins with mutations in key regulatory motifs of NS5B – the C-terminal tail and β-loop – in conjunction with a diverse set of NS5B allosteric inhibitors, we show that thumb site II inhibitors possess a distinct mechanism of action. A combination of enzyme activity studies and direct binding assays reveals that these inhibitors require both regulatory elements to maintain the polymerase inhibitory activity. Removal of either element has little impact on the binding affinity of thumb site II inhibitors, but significantly reduces their potency. NS5B in complex with a thumb site II inhibitor displays a characteristic melting profile that suggests stabilization not only of the thumb domain but also the whole polymerase. Successive truncations of the C-terminal tail and/or removal of the β-loop lead to progressive destabilization of the protein. Furthermore, the thermal unfolding transitions characteristic for thumb site II inhibitor – NS5B complex are absent in the inhibitor – bound constructs in which interactions between C-terminal tail and β-loop are abolished, pointing to the pivotal role of both regulatory elements in communication between domains. Taken together, a comprehensive picture of inhibition by compounds binding to thumb site II emerges: inhibitor binding provides stabilization of the entire polymerase in an inactive, closed conformation, propagated via coupled interactions between the C-terminal tail and β-loop.
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Affiliation(s)
- Sarah E. Boyce
- Gilead Sciences Inc., Foster City, California, United States of America
| | - Neeraj Tirunagari
- Gilead Sciences Inc., Foster City, California, United States of America
| | | | - Jason Perry
- Gilead Sciences Inc., Foster City, California, United States of America
| | - Melanie Wong
- Gilead Sciences Inc., Foster City, California, United States of America
| | - Elaine Kan
- Gilead Sciences Inc., Foster City, California, United States of America
| | - Leanna Lagpacan
- Gilead Sciences Inc., Foster City, California, United States of America
| | - Ona Barauskas
- Gilead Sciences Inc., Foster City, California, United States of America
| | - Magdeleine Hung
- Gilead Sciences Inc., Foster City, California, United States of America
| | - Martijn Fenaux
- Gilead Sciences Inc., Foster City, California, United States of America
| | - Todd Appleby
- Gilead Sciences Inc., Foster City, California, United States of America
| | | | - Uli Schmitz
- Gilead Sciences Inc., Foster City, California, United States of America
| | - Roman Sakowicz
- Gilead Sciences Inc., Foster City, California, United States of America
- * E-mail:
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Abstract
Genome replication is a crucial step in the life cycle of any virus. HCV is a positive strand RNA virus and requires a set of nonstructural proteins (NS3, 4A, 4B, 5A, and 5B) as well as cis-acting replication elements at the genome termini for amplification of the viral RNA. All nonstructural proteins are tightly associated with membranes derived from the endoplasmic reticulum and induce vesicular membrane alterations designated the membranous web, harboring the viral replication sites. The viral RNA-dependent RNA polymerase NS5B is the key enzyme of RNA synthesis. Structural, biochemical, and reverse genetic studies have revealed important insights into the mode of action of NS5B and the mechanism governing RNA replication. Although a comprehensive understanding of the regulation of RNA synthesis is still missing, a number of important viral and host determinants have been defined. This chapter summarizes our current knowledge on the role of viral and host cell proteins as well as cis-acting replication elements involved in the biogenesis of the membranous web and in viral RNA synthesis.
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Affiliation(s)
- Volker Lohmann
- Department of Infectious Diseases, University of Heidelberg, Heidelberg, Germany.
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Lu G, Gong P. Crystal Structure of the full-length Japanese encephalitis virus NS5 reveals a conserved methyltransferase-polymerase interface. PLoS Pathog 2013; 9:e1003549. [PMID: 23950717 PMCID: PMC3738499 DOI: 10.1371/journal.ppat.1003549] [Citation(s) in RCA: 173] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Accepted: 06/27/2013] [Indexed: 12/17/2022] Open
Abstract
The flavivirus NS5 harbors a methyltransferase (MTase) in its N-terminal ≈265 residues and an RNA-dependent RNA polymerase (RdRP) within the C-terminal part. One of the major interests and challenges in NS5 is to understand the interplay between RdRP and MTase as a unique natural fusion protein in viral genome replication and cap formation. Here, we report the first crystal structure of the full-length flavivirus NS5 from Japanese encephalitis virus. The structure completes the vision for polymerase motifs F and G, and depicts defined intra-molecular interactions between RdRP and MTase. Key hydrophobic residues in the RdRP-MTase interface are highly conserved in flaviviruses, indicating the biological relevance of the observed conformation. Our work paves the way for further dissection of the inter-regulations of the essential enzymatic activities of NS5 and exploration of possible other conformations of NS5 under different circumstances. Due to limited coding capacity, RNA viruses often generate proteins that contain more than one enzyme module to fulfill their rather complicated life cycle. Among those, the flavivirus nonstructural protein NS5 comprises an N-terminal methyltransferase (MTase) and a C-terminal RNA-dependent RNA polymerase (RdRP), playing key roles in processes including viral genome replication and capping. Although high-resolution crystal structures are available for MTase or RdRP alone, the intra-molecular interactions between the two modules remain elusive. By solving the crystal-structure of the full-length Japanese encephalitis virus NS5, we provide the first high-resolution readout of NS5 in its integrity, featuring an MTase-RdRP interface that is highly conserved in flaviviruses. Flaviviruses also include other important human pathogens such as dengue, West Nile, yellow fever, and tick-borne encephalitis viruses, currently lacking effective anti-viral drug. The conserved interface revealed by our structure thus may provide possibilities for the pharmaceutical community in the development of anti-flavivirus drug in a broad-spectrum manner.
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Affiliation(s)
- Guoliang Lu
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuchang District, Wuhan, Hubei, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Peng Gong
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuchang District, Wuhan, Hubei, China
- * E-mail: ,
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Gong P, Kortus MG, Nix JC, Davis RE, Peersen OB. Structures of coxsackievirus, rhinovirus, and poliovirus polymerase elongation complexes solved by engineering RNA mediated crystal contacts. PLoS One 2013; 8:e60272. [PMID: 23667424 PMCID: PMC3648537 DOI: 10.1371/journal.pone.0060272] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 02/26/2013] [Indexed: 01/03/2023] Open
Abstract
RNA-dependent RNA polymerases play a vital role in the growth of RNA viruses where they are responsible for genome replication, but do so with rather low fidelity that allows for the rapid adaptation to different host cell environments. These polymerases are also a target for antiviral drug development. However, both drug discovery efforts and our understanding of fidelity determinants have been hampered by a lack of detailed structural information about functional polymerase-RNA complexes and the structural changes that take place during the elongation cycle. Many of the molecular details associated with nucleotide selection and catalysis were revealed in our recent structure of the poliovirus polymerase-RNA complex solved by first purifying and then crystallizing stalled elongation complexes. In the work presented here we extend that basic methodology to determine nine new structures of poliovirus, coxsackievirus, and rhinovirus elongation complexes at 2.2-2.9 Å resolution. The structures highlight conserved features of picornaviral polymerases and the interactions they make with the template and product RNA strands, including a tight grip on eight basepairs of the nascent duplex, a fully pre-positioned templating nucleotide, and a conserved binding pocket for the +2 position template strand base. At the active site we see a pre-bound magnesium ion and there is conservation of a non-standard backbone conformation of the template strand in an interaction that may aid in triggering RNA translocation via contact with the conserved polymerase motif B. Moreover, by engineering plasticity into RNA-RNA contacts, we obtain crystal forms that are capable of multiple rounds of in-crystal catalysis and RNA translocation. Together, the data demonstrate that engineering flexible RNA contacts to promote crystal lattice formation is a versatile platform that can be used to solve the structures of viral RdRP elongation complexes and their catalytic cycle intermediates.
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Affiliation(s)
- Peng Gong
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Matthew G. Kortus
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Jay C. Nix
- Molecular Biology Consortium, Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Ralph E. Davis
- Cocrystal Discovery Inc., Mountain View, California, United States of America
| | - Olve B. Peersen
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, United States of America
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Cheek MA, Sharaf ML, Dobrikov MI, Shaw BR. Inhibition of hepatitis C viral RNA-dependent RNA polymerase by α-P-boranophosphate nucleotides: exploring a potential strategy for mechanism-based HCV drug design. Antiviral Res 2013; 98:144-52. [PMID: 23466667 PMCID: PMC3653414 DOI: 10.1016/j.antiviral.2013.02.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 02/02/2013] [Accepted: 02/21/2013] [Indexed: 12/31/2022]
Abstract
Improved treatments for chronic HCV infections remain a challenge, and new chemical strategies are needed to expand the current paradigm. The HCV RNA polymerase (RdR(P)) has been a target for antiviral development. For the first time we show that the boranophosphate (BP) modification increases the substrate efficiency of ATP analogs into HCV NS5BΔ55 RdRP-catalyzed RNA. Boranophosphate nucleotides contain a borane (BH₃) group substituted for a non-bridging phosphoryl oxygen of a normal phosphate group, resulting in a class of modified isoelectronic DNA and RNA mimics capable of modulating the reading and writing of genetic information. We determine that HCV NS5BΔ55, being a stereospecific enzyme, incorporates the Rp isomer of both ATPαB and the two boranophosphate analogs: 2'-O-methyladenosine 5'-(α-P-borano) triphosphate (2'-OMe ATPαB, 5a) and 3'-deoxyadenosine 5'-(α-P-borano) triphosphate (3'-dATPαB, 5b). The R(p) diastereomer of ATPαB (6), having no ribose modifications, was found to be a slightly better substrate than natural ATP, showing a 42% decrease in the apparent Michaelis-Menten constant (K(m)). The IC₅₀ of both 2'-O-Me and 3'-deoxy ATP was decreased with the boranophosphate modification up to 16-fold. This "borano effect" was further confirmed by determining the steady-state inhibitory constant (K(i)), showing a comparable potency shift (21-fold). These experiments also indicate that the boranophosphate analogs 5a and 5b inhibit HCV NS5B through a competitive mode of inhibition. This evidence, together with previous crystal structure data, further supports the idea that HCV NS5B (in a similar manner to HIV-1 RT) discriminates against the 3'-deoxy modification via lost interactions between the 3'-OH on the ribose and the active site residues, or lost intramolecular hydrogen bonding interactions between the 3'-OH and the pyrophosphate leaving group during phosphoryl transfer. To our knowledge, these data represent the first time a phosphate modified NTP has been studied as a substrate for HCV NS5B RdRP.
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Affiliation(s)
| | - Mariam L. Sharaf
- Box 90346, Department of Chemistry, Duke University, Durham NC 27708-0346
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An efficient colorimetric assay for RNA synthesis by viral RNA-dependent RNA polymerases, using thermostable pyrophosphatase. Anal Biochem 2013; 434:284-6. [DOI: 10.1016/j.ab.2012.11.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 11/26/2012] [Accepted: 11/27/2012] [Indexed: 11/19/2022]
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45
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NTP-mediated nucleotide excision activity of hepatitis C virus RNA-dependent RNA polymerase. Proc Natl Acad Sci U S A 2013; 110:E348-57. [PMID: 23307808 DOI: 10.1073/pnas.1214924110] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Hepatitis C virus (HCV) RNA-dependent RNA polymerase replicates the viral genomic RNA and is a primary drug target for antiviral therapy. Previously, we described the purification of an active and stable polymerase-primer-template elongation complex. Here, we show that, unexpectedly, the polymerase elongation complex can use NTPs to excise the terminal nucleotide in nascent RNA. Mismatched ATP, UTP, or CTP could mediate excision of 3'-terminal CMP to generate the dinucleoside tetraphosphate products Ap(4)C, Up(4)C, and Cp(4)C, respectively. Pre-steady-state kinetic studies showed that the efficiency of NTP-mediated excision was highest with ATP. A chain-terminating inhibitor, 3'deoxy-CMP, could also be excised through this mechanism, suggesting important implications for nucleoside drug potency and resistance. The nucleotide excision reaction catalyzed by recombinant hepatitis C virus polymerase was 100-fold more efficient than the corresponding reaction observed with HIV reverse transcriptase.
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