1
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Mondal S, Sarvari G, Boehr DD. Picornavirus 3C Proteins Intervene in Host Cell Processes through Proteolysis and Interactions with RNA. Viruses 2023; 15:2413. [PMID: 38140654 PMCID: PMC10747604 DOI: 10.3390/v15122413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2023] [Revised: 12/07/2023] [Accepted: 12/09/2023] [Indexed: 12/24/2023] Open
Abstract
The Picornaviridae family comprises a large group of non-enveloped viruses with enormous impact on human and animal health. The picornaviral genome contains one open reading frame encoding a single polyprotein that can be processed by viral proteases. The picornaviral 3C proteases share similar three-dimensional structures and play a significant role in the viral life cycle and virus-host interactions. Picornaviral 3C proteins also have conserved RNA-binding activities that contribute to the assembly of the viral RNA replication complex. The 3C protease is important for regulating the host cell response through the cleavage of critical host cell proteins, acting to selectively 'hijack' host factors involved in gene expression, promoting picornavirus replication, and inactivating key factors in innate immunity signaling pathways. The protease and RNA-binding activities of 3C are involved in viral polyprotein processing and the initiation of viral RNA synthesis. Most importantly, 3C modifies critical molecules in host organelles and maintains virus infection by subtly subverting host cell death through the blocking of transcription, translation, and nucleocytoplasmic trafficking to modulate cell physiology for viral replication. Here, we discuss the molecular mechanisms through which 3C mediates physiological processes involved in promoting virus infection, replication, and release.
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Affiliation(s)
| | | | - David D. Boehr
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
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2
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Winston DS, Boehr DD. Allosteric and dynamic control of RNA-dependent RNA polymerase function and fidelity. Enzymes 2021; 49:149-193. [PMID: 34696831 DOI: 10.1016/bs.enz.2021.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
All RNA viruses encode an RNA-dependent RNA polymerase (RdRp) responsible for genome replication. It is now recognized that enzymes in general, and RdRps specifically, are dynamic macromolecular machines such that their moving parts, including active site loops, play direct functional roles. While X-ray crystallography has provided deep insight into structural elements important for RdRp function, this methodology generally provides only static snapshots, and so is limited in its ability to report on dynamic fluctuations away from the lowest energy conformation. Nuclear magnetic resonance (NMR), molecular dynamics (MD) simulations and other biophysical techniques have brought new insight into RdRp function by their ability to characterize the trajectories, kinetics and thermodynamics of conformational motions. In particular, these methodologies have identified coordinated motions among conserved structural motifs necessary for nucleotide selection and incorporation. Disruption of these motions through amino acid substitutions or inhibitor binding impairs RdRp function. Understanding and re-engineering these motions thus provides exciting new avenues for anti-viral strategies. This chapter outlines the basics of these methodologies, summarizes the dynamic motions observed in different RdRps important for nucleotide selection and incorporation, and illustrates how this information can be leveraged towards rational vaccine strain development and anti-viral drug design.
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Affiliation(s)
- Dennis S Winston
- Department of Chemistry, The Pennsylvania State University, University Park, PA, United States
| | - David D Boehr
- Department of Chemistry, The Pennsylvania State University, University Park, PA, United States.
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3
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The Picornavirus Precursor 3CD Has Different Conformational Dynamics Compared to 3C pro and 3D pol in Functionally Relevant Regions. Viruses 2021; 13:v13030442. [PMID: 33803479 PMCID: PMC8001691 DOI: 10.3390/v13030442] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 03/06/2021] [Accepted: 03/08/2021] [Indexed: 02/07/2023] Open
Abstract
Viruses have evolved numerous strategies to maximize the use of their limited genetic material, including proteolytic cleavage of polyproteins to yield products with different functions. The poliovirus polyprotein 3CD is involved in important protein-protein, protein-RNA and protein-lipid interactions in viral replication and infection. It is a precursor to the 3C protease and 3D RNA-dependent RNA polymerase, but has different protease specificity, is not an active polymerase, and participates in other interactions differently than its processed products. These functional differences are poorly explained by the known X-ray crystal structures. It has been proposed that functional differences might be due to differences in conformational dynamics between 3C, 3D and 3CD. To address this possibility, we conducted nuclear magnetic resonance spectroscopy experiments, including multiple quantum relaxation dispersion, chemical exchange saturation transfer and methyl spin-spin relaxation, to probe conformational dynamics across multiple timescales. Indeed, these studies identified differences in conformational dynamics in functionally important regions, including enzyme active sites, and RNA and lipid binding sites. Expansion of the conformational ensemble available to 3CD may allow it to perform additional functions not observed in 3C and 3D alone despite having nearly identical lowest-energy structures.
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4
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Watkins CL, Kempf BJ, Beaucourt S, Barton DJ, Peersen OB. Picornaviral polymerase domain exchanges reveal a modular basis for distinct biochemical activities of viral RNA-dependent RNA polymerases. J Biol Chem 2020; 295:10624-10637. [PMID: 32493771 PMCID: PMC7397104 DOI: 10.1074/jbc.ra120.013906] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 05/28/2020] [Indexed: 01/23/2023] Open
Abstract
Picornaviral RNA-dependent RNA polymerases (RdRPs) have low replication fidelity that is essential for viral fitness and evolution. Their global fold consists of the classical "cupped right hand" structure with palm, fingers, and thumb domains, and these RdRPs also possess a unique contact between the fingers and thumb domains. This interaction restricts movements of the fingers, and RdRPs use a subtle conformational change within the palm domain to close their active sites for catalysis. We have previously shown that this core RdRP structure and mechanism provide a platform for polymerases to fine-tune replication rates and fidelity to optimize virus fitness. Here, we further elucidated the structural basis for differences in replication rates and fidelity among different viruses by generating chimeric RdRPs from poliovirus and coxsackievirus B3. We designed these chimeric polymerases by exchanging the fingers, pinky finger, or thumb domains. The results of biochemical, rapid-quench, and stopped-flow assays revealed that differences in biochemical activity map to individual modular domains of this polymerase. We found that the pinky finger subdomain is a major regulator of initiation and that the palm domain is the major determinant of catalytic rate and nucleotide discrimination. We further noted that thumb domain interactions with product RNA regulate translocation and that the palm and thumb domains coordinately control elongation complex stability. Several RdRP chimeras supported the growth of infectious poliovirus, providing insights into enterovirus species-specific protein-protein interactions required for virus replication.
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Affiliation(s)
- Colleen L Watkins
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, USA
| | - Brian J Kempf
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | | | - David J Barton
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Olve B Peersen
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, USA
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5
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Boehr AK, Arnold JJ, Oh HS, Cameron CE, Boehr DD. 2'-C-methylated nucleotides terminate virus RNA synthesis by preventing active site closure of the viral RNA-dependent RNA polymerase. J Biol Chem 2019; 294:16897-16907. [PMID: 31575662 PMCID: PMC6851289 DOI: 10.1074/jbc.ra119.010214] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 09/28/2019] [Indexed: 01/25/2023] Open
Abstract
The 2'-C-methyl ribonucleosides are nucleoside analogs representing an important class of antiviral agents, especially against positive-strand RNA viruses. Their value is highlighted by the highly successful anti-hepatitis C drug sofosbuvir. When appropriately phosphorylated, these nucleotides are successfully incorporated into RNA by the virally encoded RNA-dependent RNA polymerase (RdRp). This activity prevents further RNA extension, but the mechanism is poorly characterized. Previously, we had identified NMR signatures characteristic of formation of RdRp-RNA binary and RdRp-RNA-NTP ternary complexes for the poliovirus RdRp, including an open-to-closed conformational change necessary to prepare the active site for catalysis of phosphoryl transfer. Here we used these observations as a framework for interpreting the effects of 2'-C-methyl adenosine analogs on RNA chain extension in solution-state NMR spectroscopy experiments, enabling us to gain additional mechanistic insights into 2'-C-methyl ribonucleoside-mediated RNA chain termination. Contrary to what has been proposed previously, poliovirus RdRp that was bound to RNA with an incorporated 2'-C-methyl nucleotide could still bind to the next incoming NTP. Our results also indicated that incorporation of the 2'-C-methyl nucleotide does not disrupt RdRp-RNA interactions and does not prevent translocation. Instead, incorporation of the 2'-C-methyl nucleotide blocked closure of the RdRp active site upon binding of the next correct incoming NTP, which prevented further nucleotide addition. We propose that other nucleotide analogs that act as nonobligate chain terminators may operate through a similar mechanism.
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Affiliation(s)
- Alyson K Boehr
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802
| | - Jamie J Arnold
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802
| | - Hyung S Oh
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802
| | - Craig E Cameron
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802
| | - David D Boehr
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802
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6
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Shi J, Perryman JM, Yang X, Liu X, Musser DM, Boehr AK, Moustafa IM, Arnold JJ, Cameron CE, Boehr DD. Rational Control of Poliovirus RNA-Dependent RNA Polymerase Fidelity by Modulating Motif-D Loop Conformational Dynamics. Biochemistry 2019; 58:3735-3743. [PMID: 31424194 DOI: 10.1021/acs.biochem.9b00497] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The conserved structural motif D is an important determinant of the speed and fidelity of viral RNA-dependent RNA polymerases (RdRps). Structural and computational studies have suggested that conformational changes in the motif-D loop that help to reposition the catalytic lysine represent critical steps in nucleotide selection and incorporation. Conformations of the motif-D loop in the poliovirus RdRp are likely controlled in part by noncovalent interactions involving the motif-D residue Glu364. This residue swivels between making interactions with Lys228 and Asn370 to stabilize the open and closed loop conformations, respectively. We show here that we can rationally control the motif-D loop conformation by breaking these interactions. The K228A variant favors a more active closed conformation, leading to increased nucleotide incorporation rates and decreased nucleotide selectivity, and the N370A variant favors a less active open conformation, leading to decreased nucleotide incorporation rates and increased nucleotide selectivity. Similar competing interactions likely control nucleotide incorporation rates and fidelity in other viral RdRps. Rational engineering of these interactions may be important in the generation of live, attenuated vaccine strains, considering the established relationships between RdRp function and viral pathogenesis.
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Affiliation(s)
- Jingjing Shi
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Jacob M Perryman
- Department of Biochemistry and Molecular Biology , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Xiaorong Yang
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Xinran Liu
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Derek M Musser
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Alyson K Boehr
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Ibrahim M Moustafa
- Department of Biochemistry and Molecular Biology , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Jamie J Arnold
- Department of Biochemistry and Molecular Biology , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Craig E Cameron
- Department of Biochemistry and Molecular Biology , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - David D Boehr
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , United States
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7
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Crowley EL, Rafferty SP. Review of lactose-driven auto-induction expression of isotope-labelled proteins. Protein Expr Purif 2019; 157:70-85. [PMID: 30708035 DOI: 10.1016/j.pep.2019.01.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2019] [Accepted: 01/18/2019] [Indexed: 02/06/2023]
Abstract
NMR is an important method in the structural and functional characterization of proteins, but such experiments typically require isotopic labelling because of the low natural abundance of the nuclei of interest. Isotope-labelled protein for NMR experiments is typically obtained from IPTG-inducible bacterial expression systems in a minimal media that contains labelled carbon or nitrogen sources. Optimization of expression conditions is crucial yet challenging; large amounts of labelled protein are desired, yet protein yields are lower in minimal media, while the labelled precursors are expensive. Faced with these challenges there is a growing body of literature that apply innovative methods of induction to optimize the yield of isotope-labelled protein. A promising technique is lactose-driven auto-induction as it mitigates user intervention and can lead to higher protein yields. This review assesses the current advances and limitations surrounding the ability of researchers to isotope label proteins using auto-induction, and it identifies key components for optimization.
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Affiliation(s)
- Erika L Crowley
- Environmental and Life Sciences Graduate Program, Trent University, 1600 West Bank Drive, Peterborough, ON, K9J 0G2, Canada.
| | - Steven P Rafferty
- Department of Chemistry, Trent University, 1600 West Bank Drive, Peterborough, ON, K9J 0G2, Canada.
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8
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Gorman SD, Sahu D, O'Rourke KF, Boehr DD. Assigning methyl resonances for protein solution-state NMR studies. Methods 2018; 148:88-99. [PMID: 29958930 DOI: 10.1016/j.ymeth.2018.06.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 06/16/2018] [Accepted: 06/18/2018] [Indexed: 10/28/2022] Open
Abstract
Solution-state NMR is an important tool for studying protein structure and function. The ability to probe methyl groups has substantially expanded the scope of proteins accessible by NMR spectroscopy, including facilitating study of proteins and complexes greater than 100 kDa in size. While the toolset for studying protein structure and dynamics by NMR continues to grow, a major rate-limiting step in these studies is the initial resonance assignments, especially for larger (>50 kDa) proteins. In this practical review, we present strategies to efficiently isotopically label proteins, delineate NMR pulse sequences that can be used to determine methyl resonance assignments in the presence and absence of backbone assignments, and outline computational methods for NMR data analysis. We use our experiences from assigning methyl resonances for the aromatic biosynthetic enzymes tryptophan synthase and chorismate mutase to provide advice for all stages of experimental set-up and data analysis.
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Affiliation(s)
- Scott D Gorman
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
| | - Debashish Sahu
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
| | - Kathleen F O'Rourke
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
| | - David D Boehr
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA.
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9
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Selisko B, Papageorgiou N, Ferron F, Canard B. Structural and Functional Basis of the Fidelity of Nucleotide Selection by Flavivirus RNA-Dependent RNA Polymerases. Viruses 2018; 10:v10020059. [PMID: 29385764 PMCID: PMC5850366 DOI: 10.3390/v10020059] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 01/25/2018] [Accepted: 01/27/2018] [Indexed: 12/22/2022] Open
Abstract
Viral RNA-dependent RNA polymerases (RdRps) play a central role not only in viral replication, but also in the genetic evolution of viral RNAs. After binding to an RNA template and selecting 5'-triphosphate ribonucleosides, viral RdRps synthesize an RNA copy according to Watson-Crick base-pairing rules. The copy process sometimes deviates from both the base-pairing rules specified by the template and the natural ribose selectivity and, thus, the process is error-prone due to the intrinsic (in)fidelity of viral RdRps. These enzymes share a number of conserved amino-acid sequence strings, called motifs A-G, which can be defined from a structural and functional point-of-view. A co-relation is gradually emerging between mutations in these motifs and viral genome evolution or observed mutation rates. Here, we review our current knowledge on these motifs and their role on the structural and mechanistic basis of the fidelity of nucleotide selection and RNA synthesis by Flavivirus RdRps.
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Affiliation(s)
- Barbara Selisko
- CNRS, Aix-Marseille Université, AFMB, UMR 7257, 163 Avenue de Luminy, 13288 Marseille, France.
| | - Nicolas Papageorgiou
- CNRS, Aix-Marseille Université, AFMB, UMR 7257, 163 Avenue de Luminy, 13288 Marseille, France.
| | - François Ferron
- CNRS, Aix-Marseille Université, AFMB, UMR 7257, 163 Avenue de Luminy, 13288 Marseille, France.
| | - Bruno Canard
- CNRS, Aix-Marseille Université, AFMB, UMR 7257, 163 Avenue de Luminy, 13288 Marseille, France.
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10
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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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11
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Yang X. Conformational dynamics play important roles upon the function of N-acetylglutamate kinase. Appl Microbiol Biotechnol 2017; 101:3485-3492. [PMID: 28341883 DOI: 10.1007/s00253-017-8237-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Revised: 03/04/2017] [Accepted: 03/09/2017] [Indexed: 12/14/2022]
Abstract
N-acetylglutamate kinase (NAGK) catalyzes the phosphorylation of N-acetylglutamate. In many bacteria, NAGK catalysis is the rate controlling step in the L-arginine biosynthesis pathway from glutamate to L-arginine and is allosterically inhibited by L-arginine. Many data show that conformational dynamics of NAGKs are essential for their function. The demonstration of the conformational mechanism provides a potential way to improve the yield of arginine. Due to the lack of NAGK catalysis step in arginine synthesis route of mammals, the elucidation of the dynamic mechanism can also provide a way to design a new antivirus drug. This paper reviews how the dynamics affect the activity of NAGKs and are controlled by the effectors. X-ray crystallography and modeling data have shown that in NAGKs, the structural elements required for inhibitor and substrate binding, catalysis and product release, are highly mobile. It is possible to eliminate the inhibition of the arginine and/or block the synthesis of arginine by disturbing the flexibility of the NAGKs. Amino acid kinase family is thought to share some common dynamic features; the flexible structural elements of NAGKs have been identified, but the details of the dynamics and the signal transfer pathways are yet to be elucidated.
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Affiliation(s)
- Xiaorong Yang
- Guangdong Key Laboratory of Fermentation and Enzyme Engineering, School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, People's Republic of China. .,Guangdong Research Center of Industrial Enzyme and Green Manufacturing Technology, School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, People's Republic of China. .,Key Laboratory of Renewable Energy, Chinese Academy of Sciences, Guangzhou, 510640, People's Republic of China.
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12
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Yang X, Liu X, Musser DM, Moustafa IM, Arnold JJ, Cameron CE, Boehr DD. Triphosphate Reorientation of the Incoming Nucleotide as a Fidelity Checkpoint in Viral RNA-dependent RNA Polymerases. J Biol Chem 2017; 292:3810-3826. [PMID: 28100782 DOI: 10.1074/jbc.m116.750638] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 01/16/2017] [Indexed: 11/06/2022] Open
Abstract
The nucleotide incorporation fidelity of the viral RNA-dependent RNA polymerase (RdRp) is important for maintaining functional genetic information but, at the same time, is also important for generating sufficient genetic diversity to escape the bottlenecks of the host's antiviral response. We have previously shown that the structural dynamics of the motif D loop are closely related to nucleotide discrimination. Previous studies have also suggested that there is a reorientation of the triphosphate of the incoming nucleotide, which is essential before nucleophilic attack from the primer RNA 3'-hydroxyl. Here, we have used 31P NMR with poliovirus RdRp to show that the binding environment of the triphosphate is different when correct versus incorrect nucleotide binds. We also show that amino acid substitutions at residues known to interact with the triphosphate can alter the binding orientation/environment of the nucleotide, sometimes lead to protein conformational changes, and lead to substantial changes in RdRp fidelity. The analyses of other fidelity variants also show that changes in the triphosphate binding environment are not always accompanied by changes in the structural dynamics of the motif D loop or other regions known to be important for RdRp fidelity, including motif B. Altogether, our studies suggest that the conformational changes in motifs B and D, and the nucleoside triphosphate reorientation represent separable, "tunable" fidelity checkpoints.
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Affiliation(s)
| | | | | | - Ibrahim M Moustafa
- Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802
| | - Jamie J Arnold
- Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802
| | - Craig E Cameron
- Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802
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13
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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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14
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Abstract
By now, it is well established that the error rate of the RNA-dependent RNA polymerase (RdRp) that replicates RNA virus genomes is a primary driver of the mutation frequencies observed in RNA virus populations-the basis for the RNA quasispecies. Over the last 10 years, a considerable amount of work has uncovered the molecular determinants of replication fidelity in this enzyme. The isolation of high- and low-fidelity variants for several RNA viruses, in an expanding number of viral families, provides evidence that nature has optimized the fidelity to facilitate genetic diversity and adaptation, while maintaining genetic integrity and infectivity. This chapter will provide an overview of what fidelity variants tell us about RNA virus biology and how they may be used in antiviral approaches.
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Affiliation(s)
- Esteban Domingo
- Campus de Cantoblanco, Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Madrid, Spain
| | - Peter Schuster
- The Santa Fe Institute, Santa Fe, NM, USA and Institut f. Theoretische Chemie, Universität Wien, Vienna, Austria
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15
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Cameron CE, Moustafa IM, Arnold JJ. Fidelity of Nucleotide Incorporation by the RNA-Dependent RNA Polymerase from Poliovirus. Enzymes 2016; 39:293-323. [PMID: 27241934 DOI: 10.1016/bs.enz.2016.02.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Using poliovirus (PV) and its RNA-dependent RNA polymerase (RdRp) as our primary model system, we have advanced knowledge fundamental to the chemistry and fidelity of nucleotide addition by nucleic acid polymerase. Two fidelity checkpoints exist prior to nucleotide addition. The first toggles the enzyme between a nucleotide binding-occluded state and a nucleotide binding-competent state. The second represents an ensemble of conformational states of conserved structural motifs that permits retention of the incoming nucleotide in a state competent for phosphoryl transfer long enough for chemistry to occur. Nucleophilic attack of the alpha-phosphorous atom of the incoming nucleotide produces a pentavalent transition state, collapse of which is facilitated by protonation of the pyrophosphate leaving group by a general acid. All of the relevant conformational states of the enzyme are controlled by a network of interacting residues that permits remote-site residues to control active-site function. The current state of the art for PV RdRp enzymology is such that mechanisms governing fidelity of this enzyme can now be targeted genetically and chemically for development of attenuated viruses and antiviral agents, respectively. Application of the knowledge obtained with the PV RdRp to the development of vaccines and antivirals for emerging RNA viruses represents an important goal for the future.
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Affiliation(s)
- C E Cameron
- The Pennsylvania State University, University Park, PA, United States.
| | - I M Moustafa
- The Pennsylvania State University, University Park, PA, United States
| | - J J Arnold
- The Pennsylvania State University, University Park, PA, United States
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16
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Low-Fidelity Polymerases of Alphaviruses Recombine at Higher Rates To Overproduce Defective Interfering Particles. J Virol 2015; 90:2446-54. [PMID: 26676773 PMCID: PMC4810721 DOI: 10.1128/jvi.02921-15] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 12/08/2015] [Indexed: 01/20/2023] Open
Abstract
Low-fidelity RNA-dependent RNA polymerases for many RNA virus mutators have been shown to confer attenuated phenotypes, presumably due to increased mutation rates. Additionally, for many RNA viruses, replication to high titers results in the production of defective interfering particles (DIs) that also attenuate infection. We hypothesized that fidelity, recombination, and DI production are tightly linked. We show that a Sindbis virus mutator replicating at a high multiplicity of infection manifests an earlier and greater accumulation of DIs than its wild-type counterpart. The isolated DIs interfere with the replication of full-length virus in a dose-dependent manner. Importantly, the ability of the mutator virus to overproduce DIs could be linked to an increased recombination frequency. These data confirm that RNA-dependent RNA polymerase fidelity and recombination are inversely correlated for this mutator. Our findings suggest that defective interference resulting from higher recombination rates may be more detrimental to RNA virus mutators than the increase in mutational burden. IMPORTANCE Replication, adaptation, and evolution of RNA viruses rely in large part on their low-fidelity RNA-dependent RNA polymerase. Viruses artificially modified in their polymerases to decrease fidelity (mutator viruses) are attenuated in vivo, demonstrating the important role of fidelity in viral fitness. However, attenuation was attributed solely to the modification of the viral mutation rate and the accumulation of detrimental point mutations. In this work, we described an additional phenotype of mutator viruses: an increased recombination rate leading to defective interfering particle (DI) overproduction. Because DIs are known for their inhibitory effect on viral replication, our work suggests that fidelity variants may be attenuated in vivo via several mechanisms. This has important implications in the development of fidelity variants as live attenuated vaccine strains.
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Nucleobase but not Sugar Fidelity is Maintained in the Sabin I RNA-Dependent RNA Polymerase. Viruses 2015; 7:5571-86. [PMID: 26516899 PMCID: PMC4632402 DOI: 10.3390/v7102894] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Revised: 10/17/2015] [Accepted: 10/18/2015] [Indexed: 12/17/2022] Open
Abstract
The Sabin I poliovirus live, attenuated vaccine strain encodes for four amino acid changes (i.e., D53N, Y73H, K250E, and T362I) in the RNA-dependent RNA polymerase (RdRp). We have previously shown that the T362I substitution leads to a lower fidelity RdRp, and viruses encoding this variant are attenuated in a mouse model of poliovirus. Given these results, it was surprising that the nucleotide incorporation rate and nucleobase fidelity of the Sabin I RdRp is similar to that of wild-type enzyme, although the Sabin I RdRp is less selective against nucleotides with modified sugar groups. We suggest that the other Sabin amino acid changes (i.e., D53N, Y73H, K250E) help to re-establish nucleotide incorporation rates and nucleotide discrimination near wild-type levels, which may be a requirement for the propagation of the virus and its efficacy as a vaccine strain. These results also suggest that the nucleobase fidelity of the Sabin I RdRp likely does not contribute to viral attenuation.
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18
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Alphonse S, Bhattacharya S, Wang H, Ghose R. Methyl Relaxation Measurements Reveal Patterns of Fast Dynamics in a Viral RNA-Directed RNA Polymerase. Biochemistry 2015; 54:5828-38. [PMID: 26333183 DOI: 10.1021/acs.biochem.5b00828] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Molecular dynamics (MD) simulations combined with biochemical studies have suggested the presence of long-range networks of functionally relevant conformational flexibility on the nanosecond time scale in single-subunit RNA polymerases in many RNA viruses. However, experimental verification of these dynamics at a sufficient level of detail has been lacking. Here we describe the fast, picosecond to nanosecond dynamics of an archetypal viral RNA-directed RNA polymerase (RdRp), the 75 kDa P2 protein from cystovirus ϕ12, using analyses of (1)H-(1)H dipole-dipole cross-correlated relaxation at the methyl positions of Ile (δ1), Leu, Val, and Met residues. Our results, which represent the most detailed experimental characterization of fast dynamics in a viral RdRp until date, reveal a highly connected dynamic network as predicted by MD simulations of related systems. Our results suggest that the entry portals for template RNA and substrate NTPs are relatively disordered, while conserved motifs involved in metal binding, nucleotide selection, and catalysis display greater rigidity. Perturbations at the active site through metal binding or functional mutation affect dynamics not only in the immediate vicinity but also at remote regions. Comparison with the limited experimental and extensive functional and in silico results available for homologous systems suggests conservation of the overall pattern of dynamics in viral RdRps.
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Affiliation(s)
- Sébastien Alphonse
- Department of Chemistry, The City College of New York , 160 Convent Avenue, New York, New York 10031, United States
| | - Shibani Bhattacharya
- New York Structural Biology Center , 89 Convent Avenue, New York, New York 10027, United States
| | - Hsin Wang
- Department of Chemistry, The City College of New York , 160 Convent Avenue, New York, New York 10031, United States
| | - Ranajeet Ghose
- Department of Chemistry, The City College of New York , 160 Convent Avenue, New York, New York 10031, United States.,Graduate Center of the City University of New York , 365 Fifth Avenue, New York, New York 10016, United States
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19
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Van Slyke GA, Arnold JJ, Lugo AJ, Griesemer SB, Moustafa IM, Kramer LD, Cameron CE, Ciota AT. Sequence-Specific Fidelity Alterations Associated with West Nile Virus Attenuation in Mosquitoes. PLoS Pathog 2015; 11:e1005009. [PMID: 26114757 PMCID: PMC4482725 DOI: 10.1371/journal.ppat.1005009] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 06/05/2015] [Indexed: 02/06/2023] Open
Abstract
High rates of error-prone replication result in the rapid accumulation of genetic diversity of RNA viruses. Recent studies suggest that mutation rates are selected for optimal viral fitness and that modest variations in replicase fidelity may be associated with viral attenuation. Arthropod-borne viruses (arboviruses) are unique in their requirement for host cycling and may necessitate substantial genetic and phenotypic plasticity. In order to more thoroughly investigate the correlates, mechanisms and consequences of arbovirus fidelity, we selected fidelity variants of West Nile virus (WNV; Flaviviridae, Flavivirus) utilizing selection in the presence of a mutagen. We identified two mutations in the WNV RNA-dependent RNA polymerase associated with increased fidelity, V793I and G806R, and a single mutation in the WNV methyltransferase, T248I, associated with decreased fidelity. Both deep-sequencing and in vitro biochemical assays confirmed strain-specific differences in both fidelity and mutational bias. WNV fidelity variants demonstrated host-specific alterations to replicative fitness in vitro, with modest attenuation in mosquito but not vertebrate cell culture. Experimental infections of colonized and field populations of Cx. quinquefaciatus demonstrated that WNV fidelity alterations are associated with a significantly impaired capacity to establish viable infections in mosquitoes. Taken together, these studies (i) demonstrate the importance of allosteric interactions in regulating mutation rates, (ii) establish that mutational spectra can be both sequence and strain-dependent, and (iii) display the profound phenotypic consequences associated with altered replication complex function of flaviviruses. West Nile virus (WNV) is the most geographically widespread arthropod-borne virus (arbovirus) in the world. Like most arboviruses, WNV is a RNA virus which is highly mutable and exists in nature as genetically diverse mutant swarms. Although many recent studies have investigated the relationship between virus mutation rate and viral fitness, this had not previously been determined for WNV or other flaviviruses. We identified WNV mutations associated with variation in mutation rate using cell culture passage in the presence of a mutagen and engineered these mutations into an infectious WNV clone in order to investigate the causes and consequences of altered fidelity. Our results demonstrate that interactions among proteins which comprise the WNV replication complex can significantly alter both the extent and types of mutations that occur. In addition, we show that both increasing and decreasing WNV fidelity has host-specific effects on replication in cell culture and is associated with nearly complete ablation of WNV infection in mosquito vectors. These results have significant implications for our understanding of arbovirus evolution, replication complex function and arboviral fitness in mosquitoes, and identify important targets to study the determinants and mechanisms of vector competence and arbovirus fidelity.
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Affiliation(s)
- Greta A. Van Slyke
- The Arbovirus Laboratory, Wadsworth Center, New York State Department of Health, Slingerlands, New York, United States of America
| | - Jamie J. Arnold
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Alex J. Lugo
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Sara B. Griesemer
- The Arbovirus Laboratory, Wadsworth Center, New York State Department of Health, Slingerlands, New York, United States of America
| | - Ibrahim M. Moustafa
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Laura D. Kramer
- The Arbovirus Laboratory, Wadsworth Center, New York State Department of Health, Slingerlands, New York, United States of America
- Department of Biomedical Sciences, State University of New York at Albany School of Public Health, Albany, New York, United States of America
| | - Craig E. Cameron
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Alexander T. Ciota
- The Arbovirus Laboratory, Wadsworth Center, New York State Department of Health, Slingerlands, New York, United States of America
- Department of Biomedical Sciences, State University of New York at Albany School of Public Health, Albany, New York, United States of America
- * E-mail:
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20
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Huang Y, Zhang H, Tian H, Li C, Han S, Lin Y, Zheng S. Mutational analysis to identify the residues essential for the inhibition of N-acetyl glutamate kinase of Corynebacterium glutamicum. Appl Microbiol Biotechnol 2015; 99:7527-37. [DOI: 10.1007/s00253-015-6469-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Revised: 02/05/2015] [Accepted: 02/08/2015] [Indexed: 11/24/2022]
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21
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Campagnola G, McDonald S, Beaucourt S, Vignuzzi M, Peersen OB. Structure-function relationships underlying the replication fidelity of viral RNA-dependent RNA polymerases. J Virol 2015; 89:275-86. [PMID: 25320316 PMCID: PMC4301111 DOI: 10.1128/jvi.01574-14] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2014] [Accepted: 10/07/2014] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Viral RNA-dependent RNA polymerases are considered to be low-fidelity enzymes, providing high mutation rates that allow for the rapid adaptation of RNA viruses to different host cell environments. Fidelity is tuned to provide the proper balance of virus replication rates, pathogenesis, and tissue tropism needed for virus growth. Using our structures of picornaviral polymerase-RNA elongation complexes, we have previously engineered more than a dozen coxsackievirus B3 polymerase mutations that significantly altered virus replication rates and in vivo fidelity and also provided a set of secondary adaptation mutations after tissue culture passage. Here we report a biochemical analysis of these mutations based on rapid stopped-flow kinetics to determine elongation rates and nucleotide discrimination factors. The data show a spatial separation of fidelity and replication rate effects within the polymerase structure. Mutations in the palm domain have the greatest effects on in vitro nucleotide discrimination, and these effects are strongly correlated with elongation rates and in vivo mutation frequencies, with faster polymerases having lower fidelity. Mutations located at the top of the finger domain, on the other hand, primarily affect elongation rates and have relatively minor effects on fidelity. Similar modulation effects are seen in poliovirus polymerase, an inherently lower-fidelity enzyme where analogous mutations increase nucleotide discrimination. These findings further our understanding of viral RNA-dependent RNA polymerase structure-function relationships and suggest that positive-strand RNA viruses retain a unique palm domain-based active-site closure mechanism to fine-tune replication fidelity. IMPORTANCE Positive-strand RNA viruses represent a major class of human and animal pathogens with significant health and economic impacts. These viruses replicate by using a virally encoded RNA-dependent RNA polymerase enzyme that has low fidelity, generating many mutations that allow the rapid adaptation of these viruses to different tissue types and host cells. In this work, we use a structure-based approach to engineer mutations in viral polymerases and study their effects on in vitro nucleotide discrimination as well as virus growth and genome replication fidelity. These results show that mutation rates can be drastically increased or decreased as a result of single mutations at several key residues in the polymerase palm domain, and this can significantly attenuate virus growth in vivo. These findings provide a pathway for developing live attenuated virus vaccines based on engineering the polymerase to reduce virus fitness.
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Affiliation(s)
- Grace Campagnola
- Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, USA
| | - Seth McDonald
- Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, USA
| | | | | | - Olve B Peersen
- Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, USA
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22
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Moustafa IM, Korboukh VK, Arnold JJ, Smidansky ED, Marcotte LL, Gohara DW, Yang X, Sánchez-Farrán MA, Filman D, Maranas JK, Boehr DD, Hogle JM, Colina CM, Cameron CE. Structural dynamics as a contributor to error-prone replication by an RNA-dependent RNA polymerase. J Biol Chem 2014; 289:36229-48. [PMID: 25378410 DOI: 10.1074/jbc.m114.616193] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
RNA viruses encoding high- or low-fidelity RNA-dependent RNA polymerases (RdRp) are attenuated. The ability to predict residues of the RdRp required for faithful incorporation of nucleotides represents an essential step in any pipeline intended to exploit perturbed fidelity as the basis for rational design of vaccine candidates. We used x-ray crystallography, molecular dynamics simulations, NMR spectroscopy, and pre-steady-state kinetics to compare a mutator (H273R) RdRp from poliovirus to the wild-type (WT) enzyme. We show that the nucleotide-binding site toggles between the nucleotide binding-occluded and nucleotide binding-competent states. The conformational dynamics between these states were enhanced by binding to primed template RNA. For the WT, the occluded conformation was favored; for H273R, the competent conformation was favored. The resonance for Met-187 in our NMR spectra reported on the ability of the enzyme to check the correctness of the bound nucleotide. Kinetic experiments were consistent with the conformational dynamics contributing to the established pre-incorporation conformational change and fidelity checkpoint. For H273R, residues comprising the active site spent more time in the catalytically competent conformation and were more positively correlated than the WT. We propose that by linking the equilibrium between the binding-occluded and binding-competent conformations of the nucleotide-binding pocket and other active-site dynamics to the correctness of the bound nucleotide, faithful nucleotide incorporation is achieved. These studies underscore the need to apply multiple biophysical and biochemical approaches to the elucidation of the physical basis for polymerase fidelity.
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Affiliation(s)
| | | | - Jamie J Arnold
- From the Department of Biochemistry and Molecular Biology
| | | | - Laura L Marcotte
- the Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115
| | - David W Gohara
- the Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115
| | | | | | - David Filman
- the Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115
| | | | | | - James M Hogle
- the Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115
| | - Coray M Colina
- the Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 and
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23
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Boehr DD, Liu X, Yang X. Targeting structural dynamics of the RNA-dependent RNA polymerase for anti-viral strategies. Curr Opin Virol 2014; 9:194-200. [PMID: 25224392 DOI: 10.1016/j.coviro.2014.08.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 08/28/2014] [Indexed: 10/24/2022]
Abstract
The RNA-dependent RNA polymerase is responsible for genome replication of RNA viruses. Nuclear magnetic resonance experiments and molecular dynamics simulations have indicated that efficient and faithful polymerase function requires highly coordinated internal protein motions. Interference with these motions, either through amino acid substitutions or small molecule binding, can disrupt polymerase and virus function. In particular, these studies have pointed toward highly conserved structural elements, like the motif-D active-site loop, that can be modified to generate polymerases with desired properties. Viruses encoding engineered polymerases might serve as live, attenuated vaccine strains. Further elucidation of polymerase structural dynamics will also provide new avenues for anti-viral drug design.
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Affiliation(s)
- David D Boehr
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA.
| | - Xinran Liu
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
| | - Xiaorong Yang
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
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24
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Korboukh VK, Lee CA, Acevedo A, Vignuzzi M, Xiao Y, Arnold JJ, Hemperly S, Graci JD, August A, Andino R, Cameron CE. RNA virus population diversity, an optimum for maximal fitness and virulence. J Biol Chem 2014; 289:29531-44. [PMID: 25213864 DOI: 10.1074/jbc.m114.592303] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The ability of an RNA virus to exist as a population of genetically distinct variants permits the virus to overcome events during infections that would otherwise limit virus multiplication or drive the population to extinction. Viral genetic diversity is created by the ribonucleotide misincorporation frequency of the viral RNA-dependent RNA polymerase (RdRp). We have identified a poliovirus (PV) RdRp derivative (H273R) possessing a mutator phenotype. GMP misincorporation efficiency for H273R RdRp in vitro was increased by 2-3-fold that manifested in a 2-3-fold increase in the diversity of the H273R PV population in cells. Circular sequencing analysis indicated that some mutations were RdRp-independent. Consistent with the population genetics theory, H273R PV was driven to extinction more easily than WT in cell culture. Furthermore, we observed a substantial reduction in H273R PV virulence, measured as the ability to cause paralysis in the cPVR mouse model. Reduced virulence correlated with the inability of H273R PV to sustain replication in tissues/organs in which WT persists. Despite the attenuated phenotype, H273R PV was capable of replicating in mice to levels sufficient to induce a protective immune response, even when the infecting dose used was insufficient to elicit any visual signs of infection. We conclude that optimal RdRp fidelity is a virulence determinant that can be targeted for viral attenuation or antiviral therapies, and we suggest that the RdRp may not be the only source of mutations in a RNA virus genome.
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Affiliation(s)
| | - Cheri A Lee
- From the Departments of Biochemistry and Molecular Biology and
| | - Ashley Acevedo
- the Department of Microbiology and Immunology, University of California at San Francisco, San Francisco, California 94158
| | - Marco Vignuzzi
- the Department of Microbiology and Immunology, University of California at San Francisco, San Francisco, California 94158
| | - Yinghong Xiao
- the Department of Microbiology and Immunology, University of California at San Francisco, San Francisco, California 94158
| | - Jamie J Arnold
- From the Departments of Biochemistry and Molecular Biology and
| | | | - Jason D Graci
- From the Departments of Biochemistry and Molecular Biology and
| | - Avery August
- Veterinary and Biomedical Sciences, Pennsylvania State University, University Park, Pennsylvania 16802 and
| | - Raul Andino
- the Department of Microbiology and Immunology, University of California at San Francisco, San Francisco, California 94158
| | - Craig E Cameron
- From the Departments of Biochemistry and Molecular Biology and
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25
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Sholders AJ, Peersen OB. Distinct conformations of a putative translocation element in poliovirus polymerase. J Mol Biol 2014; 426:1407-19. [PMID: 24424421 PMCID: PMC3963463 DOI: 10.1016/j.jmb.2013.12.031] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Revised: 11/27/2013] [Accepted: 12/02/2013] [Indexed: 01/01/2023]
Abstract
The mechanism whereby RNA is translocated by the single subunit viral RNA-dependent RNA polymerases is not yet understood. These enzymes lack homologs of the "O-helix" structures and associated fingers domain movements thought to be responsible for translocation in many DNA-templated polymerases. The structures of multiple picornavirus polymerase elongation complexes suggest that these enzymes use a different molecular mechanism where translocation is not strongly coupled to the opening of the active site following catalysis. Here we present the 2.0- to 2.6-Å-resolution crystal structures and biochemical data for 12 poliovirus polymerase mutants that together show how proper enzyme functions and translocation activity requires conformational flexibility of a loop sequence in the palm domain B-motif. Within the loop, the Ser288-Gly289-Cys290 sequence is shown to play a major role in the catalytic cycle based on RNA binding, processive elongation activity, and single nucleotide incorporation assays. The structures show that Ser288 forms a key hydrogen bond with Asp238, the backbone flexibility of Gly289 is required for translocation competency, and Cys290 modulates the overall elongation activity of the enzyme. Some conformations of the loop represent likely intermediates on the way to forming the catalytically competent closed active site, while others are consistent with a role in promoting translocation of the nascent base pair out of the active site. The loop structure and key residues surrounding it are highly conserved, suggesting that the structural dynamics we observe in poliovirus 3D(pol) are a common feature of viral RNA-dependent RNA polymerases.
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Affiliation(s)
- Aaron J Sholders
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523-1870, USA
| | - Olve B Peersen
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523-1870, USA.
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26
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Affiliation(s)
- David D Boehr
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA.
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27
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Crublet E, Kerfah R, Mas G, Noirclerc-Savoye M, Lantez V, Vernet T, Boisbouvier J. A cost-effective protocol for the parallel production of libraries of 13CH3-specifically labeled mutants for NMR studies of high molecular weight proteins. Methods Mol Biol 2014; 1091:229-244. [PMID: 24203337 DOI: 10.1007/978-1-62703-691-7_17] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
There is increasing interest in applying NMR spectroscopy to the study of large protein assemblies. Development of methyl-specific labeling protocols combined with improved NMR spectroscopy enable nowadays studies of proteins complexes up to 1 MDa. For such large complexes, the major interest lies in obtaining structural, dynamic and interaction information in solution, which requires sequence-specific resonance assignment of NMR signals. While such analysis is quite standard for small proteins, it remains one of the major bottlenecks when the size of the protein increases. Here, we describe implementation and latest improvements of SeSAM, a fast and user-friendly approach for assignment of methyl resonances in large proteins using mutagenesis. We have improved culture medium to boost the production of methyl-specifically labeled proteins, allowing us to perform small-scale parallel production and purification of a library of (13)CH3-specifically labeled mutants. This optimized protocol is illustrated by assignment of Alanine, Isoleucine, and Valine methyl groups of the homododecameric aminopeptidase PhTET2. We estimated that this improved method allows assignment of ca. 100 methyl cross-peaks in 2 weeks, including 4 days of NMR time and less than 2 k€ of isotopic materials.
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Affiliation(s)
- Elodie Crublet
- Institut de Biologie Structurale Jean-Pierre Ebel, CEA, Grenoble, France
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28
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Liu X, Yang X, Lee CA, Moustafa IM, Smidansky ED, Lum D, Arnold JJ, Cameron CE, Boehr DD. Vaccine-derived mutation in motif D of poliovirus RNA-dependent RNA polymerase lowers nucleotide incorporation fidelity. J Biol Chem 2013; 288:32753-32765. [PMID: 24085299 DOI: 10.1074/jbc.m113.484428] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
All viral RNA-dependent RNA polymerases (RdRps) have a conserved structural element termed motif D. Studies of the RdRp from poliovirus (PV) have shown that a conformational change of motif D leads to efficient and faithful nucleotide addition by bringing Lys-359 into the active site where it serves as a general acid. The RdRp of the Sabin I vaccine strain has Thr-362 changed to Ile. Such a drastic change so close to Lys-359 might alter RdRp function and contribute in some way to the attenuated phenotype of Sabin type I. Here we present our characterization of the T362I RdRp. We find that the T362I RdRp exhibits a mutator phenotype in biochemical experiments in vitro. Using NMR, we show that this change in nucleotide incorporation fidelity correlates with a change in the structural dynamics of motif D. A recombinant PV expressing the T362I RdRp exhibits normal growth properties in cell culture but expresses a mutator phenotype in cells. For example, the T362I-containing PV is more sensitive to the mutagenic activity of ribavirin than wild-type PV. Interestingly, the T362I change was sufficient to cause a statistically significant reduction in viral virulence. Collectively, these studies suggest that residues of motif D can be targeted when changes in nucleotide incorporation fidelity are desired. Given the observation that fidelity mutants can serve as vaccine candidates, it may be possible to use engineering of motif D for this purpose.
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Affiliation(s)
| | | | - Cheri A Lee
- the Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Ibrahim M Moustafa
- the Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Eric D Smidansky
- the Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
| | | | - Jamie J Arnold
- the Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Craig E Cameron
- the Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
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29
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Abstract
The spatial structure of the cell is highly organized at all levels: from small complexes and assemblies, to local nano- and microclusters, to global, micrometer scales across and between cells. We suggest that this multiscale spatial cell organization also organizes signaling and coordinates cellular behavior. We propose a new view of the spatial structure of cell signaling systems. This new view describes cell signaling in terms of dynamic allosteric interactions within and among distinct, spatially organized transient clusters. The clusters vary over time and space and are on length scales from nanometers to micrometers. When considered across these length scales, primary factors in the spatial organization are cell membrane domains and the actin cytoskeleton, both also highly dynamic. A key challenge is to understand the interplay across these multiple scales, link it to the physicochemical basis of the conformational behavior of single molecules and ultimately relate it to cellular function. Overall, our premise is that at these scales, cell signaling should be thought of not primarily as a sequence of diffusion-controlled molecular collisions, but instead transient, allostery-driven cluster re-forming interactions.
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Affiliation(s)
- Ruth Nussinov
- Basic Research Program, SAIC-Frederick, Inc., Cancer and Inflammation Program, National Cancer Institute, Frederick, MD 21702
- Sackler Inst. of Molecular Medicine, Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
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30
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Chang YG, Tseng R, Kuo NW, LiWang A. Nuclear magnetic resonance spectroscopy of the circadian clock of cyanobacteria. Integr Comp Biol 2013; 53:93-102. [PMID: 23667047 DOI: 10.1093/icb/ict054] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The most well-understood circadian clock at the level of molecular mechanisms is that of cyanobacteria. This overview is on how solution-state nuclear magnetic resonance (NMR) spectroscopy has contributed to this understanding. By exciting atomic spin-½ nuclei in a strong magnetic field, NMR obtains information on their chemical environments, inter-nuclear distances, orientations, and motions. NMR protein samples are typically aqueous, often at near-physiological pH, ionic strength, and temperature. The level of information obtainable by NMR depends on the quality of the NMR sample, by which we mean the solubility and stability of proteins. Here, we use examples from our laboratory to illustrate the advantages and limitations of the technique.
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Affiliation(s)
- Yong-Gang Chang
- School of Natural Sciences, University of California at Merced, Merced, CA 95343, USA
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31
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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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Abstract
Allosteric propagation results in communication between distinct sites in the protein structure; it also encodes specific effects on cellular pathways, and in this way it shapes cellular response. One example of long-range effects is binding of morphogens to cell surface receptors, which initiates a cascade of protein interactions that leads to genome activation and specific cellular action. Allosteric propagation results from combinations of multiple factors, takes place through dynamic shifts of conformational ensembles, and affects the equilibria of macromolecular interactions. Here, we (a) emphasize the well-known yet still underappreciated role of allostery in conveying explicit signals across large multimolecular assemblies and distances to specify cellular action; (b) stress the need for quantitation of the allosteric effects; and finally, (c) propose that each specific combination of allosteric effectors along the pathway spells a distinct function. The challenges are colossal; the inspiring reward will be predicting function, misfunction, and outcomes of drug regimes.
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Affiliation(s)
- Ruth Nussinov
- Basic Research Program, SAIC-Frederick, Inc., Center for Cancer Research Nanobiology Program, National Cancer Institute, Frederick, Maryland 21702, USA.
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Benoit MPMH, Imbert L, Palencia A, Pérard J, Ebel C, Boisbouvier J, Plevin MJ. The RNA-binding region of human TRBP interacts with microRNA precursors through two independent domains. Nucleic Acids Res 2013; 41:4241-52. [PMID: 23435228 PMCID: PMC3627579 DOI: 10.1093/nar/gkt086] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression through RNA interference. Human miRNAs are generated through a series of enzymatic processing steps. The precursor miRNA (pre-miRNA) is recognized and cleaved by a complex containing Dicer and several non-catalytic accessory proteins. HIV TAR element binding protein (TRBP) is a constituent of the Dicer complex, which augments complex stability and potentially functions in substrate recognition and product transfer to the RNA-induced silencing complex. Here we have analysed the interaction between the RNA-binding region of TRBP and an oncogenic human miRNA, miR-155, at different stages in the biogenesis pathway. We show that the region of TRBP that binds immature miRNAs comprises two independent double-stranded RNA-binding domains connected by a 60-residue flexible linker. No evidence of contact between the two double-stranded RNA-binding domains was observed either in the apo- or RNA-bound state. We establish that the RNA-binding region of TRBP interacts with both pre-miR-155 and the miR-155/miR-155* duplex through the same binding surfaces and with similar affinities, and that two protein molecules can simultaneously interact with each immature miRNA. These data suggest that TRBP could play a role before and after processing of pre-miRNAs by Dicer.
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Gnädig NF, Beaucourt S, Campagnola G, Bordería AV, Sanz-Ramos M, Gong P, Blanc H, Peersen OB, Vignuzzi M. Coxsackievirus B3 mutator strains are attenuated in vivo. Proc Natl Acad Sci U S A 2012; 109:E2294-303. [PMID: 22853955 PMCID: PMC3427060 DOI: 10.1073/pnas.1204022109] [Citation(s) in RCA: 116] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Based on structural data of the RNA-dependent RNA polymerase, rational targeting of key residues, and screens for Coxsackievirus B3 fidelity variants, we isolated nine polymerase variants with mutator phenotypes, which allowed us to probe the effects of lowering fidelity on virus replication, mutability, and in vivo fitness. These mutator strains generate higher mutation frequencies than WT virus and are more sensitive to mutagenic treatments, and their purified polymerases present lower-fidelity profiles in an in vitro incorporation assay. Whereas these strains replicate with WT-like kinetics in tissue culture, in vivo infections reveal a strong correlation between mutation frequency and fitness. Variants with the highest mutation frequencies are less fit in vivo and fail to productively infect important target organs, such as the heart or pancreas. Furthermore, whereas WT virus is readily detectable in target organs 30 d after infection, some variants fail to successfully establish persistent infections. Our results show that, although mutator strains are sufficiently fit when grown in large population size, their fitness is greatly impacted when subjected to severe bottlenecking, which would occur during in vivo infection. The data indicate that, although RNA viruses have extreme mutation frequencies to maximize adaptability, nature has fine-tuned replication fidelity. Our work forges ground in showing that the mutability of RNA viruses does have an upper limit, where larger than natural genetic diversity is deleterious to virus survival.
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Affiliation(s)
- Nina F. Gnädig
- Institut Pasteur, Centre National de la Recherche Scientifique Unité de Recherche Associée 3015, 75724 Paris Cedex 15, France
- University of Paris Diderot, Sorbonne Paris Cite, Cellule Pasteur, 75015 Paris, France; and
| | - Stéphanie Beaucourt
- Institut Pasteur, Centre National de la Recherche Scientifique Unité de Recherche Associée 3015, 75724 Paris Cedex 15, France
| | - Grace Campagnola
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523
| | - Antonio V. Bordería
- Institut Pasteur, Centre National de la Recherche Scientifique Unité de Recherche Associée 3015, 75724 Paris Cedex 15, France
| | - Marta Sanz-Ramos
- Institut Pasteur, Centre National de la Recherche Scientifique Unité de Recherche Associée 3015, 75724 Paris Cedex 15, France
| | - Peng Gong
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523
| | - Hervé Blanc
- Institut Pasteur, Centre National de la Recherche Scientifique Unité de Recherche Associée 3015, 75724 Paris Cedex 15, France
| | - Olve B. Peersen
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523
| | - Marco Vignuzzi
- Institut Pasteur, Centre National de la Recherche Scientifique Unité de Recherche Associée 3015, 75724 Paris Cedex 15, France
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35
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Yang X, Smidansky ED, Maksimchuk KR, Lum D, Welch JL, Arnold JJ, Cameron CE, Boehr DD. Motif D of viral RNA-dependent RNA polymerases determines efficiency and fidelity of nucleotide addition. Structure 2012; 20:1519-27. [PMID: 22819218 DOI: 10.1016/j.str.2012.06.012] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Revised: 05/23/2012] [Accepted: 06/18/2012] [Indexed: 01/13/2023]
Abstract
Fast, accurate nucleotide incorporation by polymerases facilitates expression and maintenance of genomes. Many polymerases use conformational dynamics of a conserved α helix to permit efficient nucleotide addition only when the correct nucleotide substrate is bound. This α helix is missing in structures of RNA-dependent RNA polymerases (RdRps) and RTs. Here, we use solution-state nuclear magnetic resonance to demonstrate that the conformation of conserved structural motif D of an RdRp is linked to the nature (correct versus incorrect) of the bound nucleotide and the protonation state of a conserved, motif-D lysine. Structural data also reveal the inability of motif D to achieve its optimal conformation after incorporation of an incorrect nucleotide. Functional data are consistent with the conformational change of motif D becoming rate limiting during and after nucleotide misincorporation. We conclude that motif D of RdRps and, by inference, RTs is the functional equivalent to the fidelity helix of other polymerases.
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Affiliation(s)
- Xiaorong Yang
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
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36
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Kortus MG, Kempf BJ, Haworth KG, Barton DJ, Peersen OB. A template RNA entry channel in the fingers domain of the poliovirus polymerase. J Mol Biol 2012; 417:263-78. [PMID: 22321798 PMCID: PMC3325025 DOI: 10.1016/j.jmb.2012.01.049] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Revised: 01/24/2012] [Accepted: 01/26/2012] [Indexed: 01/10/2023]
Abstract
Positive-strand RNA viruses within the Picornaviridae family express an RNA-dependent RNA polymerase, 3D(pol), that is required for viral RNA replication. Structures of 3D(pol) from poliovirus, coxsackievirus, human rhinoviruses, and other picornaviruses reveal a putative template RNA entry channel on the surface of the enzyme fingers domain. Basic amino acids and tyrosine residues along this entry channel are predicted to form ionic and base stacking interactions with the viral RNA template as it enters the polymerase active site. We generated a series of alanine substitution mutations at these residues in the poliovirus polymerase and assayed their effects on template RNA binding, RNA synthesis initiation, rates of RNA elongation, elongation complex (EC) stability, and virus growth. The results show that basic residues K125, R128, and R188 are important for template RNA binding, while tyrosines Y118 and Y148 are required for efficient initiation of RNA synthesis and for EC stability. Alanine substitutions of tyrosines 118 and 148 at the tip of the 3D(pol) pinky finger drastically decreased the rate of initiation as well as EC stability, but without affecting template RNA binding or RNA elongation rates. Viable poliovirus was recovered from HeLa cells transfected with mutant RNAs; however, mutations that dramatically inhibited template RNA binding (K125A-K126A and R188A), RNA synthesis initiation (Y118A, Y148A), or EC stability (Y118A, Y148A) were not stably maintained in progeny virus. These data identify key residues within the template RNA entry channel and begin to define their distinct mechanistic roles within RNA ECs.
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Affiliation(s)
- Matthew G. Kortus
- Department of Biochemistry & Molecular Biology, Colorado State University, 1870 Campus Delivery, Colorado State University, Fort Collins, CO80523-1870
| | - Brian J. Kempf
- Department of Microbiology, University of Colorado School of Medicine, Anschutz Medical Campus, Building RC-1 North, Room 9116, 12800 East 19th Avenue, MS8333, Aurora, CO 80045
| | - Kevin G. Haworth
- Department of Biochemistry & Molecular Biology, Colorado State University, 1870 Campus Delivery, Colorado State University, Fort Collins, CO80523-1870
| | - David J. Barton
- Department of Microbiology, University of Colorado School of Medicine, Anschutz Medical Campus, Building RC-1 North, Room 9116, 12800 East 19th Avenue, MS8333, Aurora, CO 80045
| | - Olve B. Peersen
- Department of Biochemistry & Molecular Biology, Colorado State University, 1870 Campus Delivery, Colorado State University, Fort Collins, CO80523-1870
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37
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Loakes D. Nucleotides and nucleic acids; oligo- and polynucleotides. ORGANOPHOSPHORUS CHEMISTRY 2012. [DOI: 10.1039/9781849734875-00169] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- David Loakes
- Medical Research Council Laboratory of Molecular Biology, Hills Road Cambridge CB2 2QH UK
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38
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Holzberger B, Pszolla MG, Marx A, Möller HM. KlenTaq DNA polymerase adopts unique recognition states when encountering matched, mismatched, and abasic template sites: an NMR study. Chembiochem 2012; 13:635-9. [PMID: 22315195 DOI: 10.1002/cbic.201100802] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2011] [Indexed: 01/10/2023]
Affiliation(s)
- Bastian Holzberger
- Department of Chemistry and Konstanz Research School Chemical Biology, University of Konstanz, Universitätsstrasse 10, 78457 Konstanz, Germany
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39
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Molecular dynamics simulations of viral RNA polymerases link conserved and correlated motions of functional elements to fidelity. J Mol Biol 2011; 410:159-81. [PMID: 21575642 PMCID: PMC3114172 DOI: 10.1016/j.jmb.2011.04.078] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Revised: 04/27/2011] [Accepted: 04/30/2011] [Indexed: 02/02/2023]
Abstract
The viral RNA-dependent RNA polymerase (RdRp) is essential for multiplication of all RNA viruses. The sequence diversity of an RNA virus population contributes to its ability to infect the host. This diversity emanates from errors made by the RdRp during RNA synthesis. The physical basis for RdRp fidelity is unclear but is linked to conformational changes occurring during the nucleotide-addition cycle. To understand RdRp dynamics that might influence RdRp function, we have analyzed all-atom molecular dynamics simulations on the nanosecond timescale of four RdRps from the picornavirus family that exhibit 30–74% sequence identity. Principal component analysis showed that the major motions observed during the simulations derived from conserved structural motifs and regions of known function. The dynamics of residues participating in the same biochemical property, for example, RNA binding, nucleotide binding or catalysis, were correlated even when spatially distant on the RdRp structure. The conserved and correlated dynamics of functional structural elements suggest coevolution of dynamics with structure and function of the RdRp. Crystal structures of all picornavirus RdRps exhibit a template–nascent RNA duplex channel too small to fully accommodate duplex RNA. Simulations revealed opening and closing motions of the RNA and nucleoside triphosphate channels, which might be relevant to nucleoside triphosphate entry, inorganic pyrophosphate exit and translocation. A role for nanosecond timescale dynamics in RdRp fidelity is supported by the altered dynamics of the high-fidelity G64S derivative of PV RdRp relative to wild-type enzyme.
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40
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Chen SCC, Chuang TJ, Li WH. The relationships among microRNA regulation, intrinsically disordered regions, and other indicators of protein evolutionary rate. Mol Biol Evol 2011; 28:2513-20. [PMID: 21398349 DOI: 10.1093/molbev/msr068] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Many indicators of protein evolutionary rate have been proposed, but some of them are interrelated. The purpose of this study is to disentangle their correlations. We assess the strength of each indicator by controlling for the other indicators under study. We find that the number of microRNA (miRNA) types that regulate a gene is the strongest rate indicator (a negative correlation), followed by disorder content (the percentage of disordered regions in a protein, a positive correlation); the strength of disorder content as a rate indicator is substantially increased after controlling for the number of miRNA types. By dividing proteins into lowly and highly intrinsically disordered proteins (L-IDPs and H-IDPs), we find that proteins interacting with more H-IDPs tend to evolve more slowly, which largely explains the previous observation of a negative correlation between the number of protein-protein interactions and evolutionary rate. Moreover, all of the indicators examined here, except for the number of miRNA types, have different strengths in L-IDPs and in H-IDPs. Finally, the number of phosphorylation sites is weakly correlated with the number of miRNA types, and its strength as a rate indicator is substantially reduced when other indicators are considered. Our study reveals the relative strength of each rate indicator and increases our understanding of protein evolution.
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Affiliation(s)
- Sean Chun-Chang Chen
- Institute of BioMedical Informatics, National Yang-Ming University, Taipei, Taiwan
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41
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Denison MR, Graham RL, Donaldson EF, Eckerle LD, Baric RS. Coronaviruses: an RNA proofreading machine regulates replication fidelity and diversity. RNA Biol 2011; 8:270-9. [PMID: 21593585 PMCID: PMC3127101 DOI: 10.4161/rna.8.2.15013] [Citation(s) in RCA: 364] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Revised: 01/27/2011] [Accepted: 01/28/2011] [Indexed: 12/18/2022] Open
Abstract
In order to survive and propagate, RNA viruses must achieve a balance between the capacity for adaptation to new environmental conditions or host cells with the need to maintain an intact and replication competent genome. Several virus families in the order Nidovirales, such as the coronaviruses (CoVs) must achieve these objectives with the largest and most complex replicating RNA genomes known, up to 32 kb of positive-sense RNA. The CoVs encode sixteen nonstructural proteins (nsp 1-16) with known or predicted RNA synthesis and modification activities, and it has been proposed that they are also responsible for the evolution of large genomes. The CoVs, including murine hepatitis virus (MHV) and SARS-CoV, encode a 3'-to-5' exoribonuclease activity (ExoN) in nsp14. Genetic inactivation of ExoN activity in engineered SARS-CoV and MHV genomes by alanine substitution at conserved DE-D-D active site residues results in viable mutants that demonstrate 15- to 20-fold increases in mutation rates, up to 18 times greater than those tolerated for fidelity mutants of other RNA viruses. Thus nsp14-ExoN is essential for replication fidelity, and likely serves either as a direct mediator or regulator of a more complex RNA proofreading machine, a process previously unprecedented in RNA virus biology. Elucidation of the mechanisms of nsp14-mediated proofreading will have major implications for our understanding of the evolution of RNA viruses, and also will provide a robust model to investigate the balance between fidelity, diversity and pathogenesis. The discovery of a protein distinct from a viral RdRp that regulates replication fidelity also raises the possibility that RNA genome replication fidelity may be adaptable to differing replication environments and selective pressures, rather than being a fixed determinant.
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Affiliation(s)
- Mark R Denison
- Department of Pediatrics and Microbiology & Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
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42
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Ren Z, Ghose R. Slow conformational dynamics in the cystoviral RNA-directed RNA polymerase P2: influence of substrate nucleotides and template RNA. Biochemistry 2011; 50:1875-84. [PMID: 21244027 DOI: 10.1021/bi101863g] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The RNA-directed RNA polymerase P2 from cystovirus ϕ6 catalyzes the de novo synthesis of positive and negative strands of the viral double-stranded RNA genome. P2 is mobile on the slow, microsecond to millisecond time scale with various motional modes, putatively assisting in RNA translocation and catalysis. Here we investigate the influence of the extreme 3'-end sequence of the single-stranded RNA templates and the nature of the substrate nucleotide triphosphates on these motional modes using multiple-quantum NMR spectroscopy. We find that P2, in the presence of templates bearing the proper genomic 3'-ends or the preferred initiation nucleotide, displays unique dynamic signatures that are different from those in the presence of nonphysiological templates or substrates. This suggests that dynamics may play a role in the fidelity of recognition of the correct substrates and template sequences to initiate RNA polymerization.
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Affiliation(s)
- Zhen Ren
- The Graduate Program in Biochemistry, Graduate Center of the City University of New York, New York, New York 10016, United States
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