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Wysong BC, Schuck PL, Sridharan M, Carrison S, Murakami Y, Balakrishnan L, Stewart JA. Human CST Stimulates Base Excision Repair to Prevent the Accumulation of Oxidative DNA Damage. J Mol Biol 2024; 436:168672. [PMID: 38908783 DOI: 10.1016/j.jmb.2024.168672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 06/14/2024] [Accepted: 06/17/2024] [Indexed: 06/24/2024]
Abstract
CTC1-STN1-TEN1 (CST) is a single-stranded DNA binding protein vital for telomere length maintenance with additional genome-wide roles in DNA replication and repair. While CST was previously shown to function in double-strand break repair and promote replication restart, it is currently unclear whether it has specialized roles in other DNA repair pathways. Proper and efficient repair of DNA is critical to protecting genome integrity. Telomeres and other G-rich regions are strongly predisposed to oxidative DNA damage in the form of 8-oxoguanines, which are typically repaired by the base-excision repair (BER) pathway. Moreover, recent studies suggest that CST functions in the repair of oxidative DNA lesions. Therefore, we tested whether CST interacts with and regulates BER protein activity. Here, we show that CST robustly stimulates proteins involved in BER, including OGG1, Pol β, APE1, and LIGI, on both telomeric and non-telomeric DNA substrates. Biochemical reconstitution of the pathway indicates that CST stimulates BER. Finally, knockout of STN1 or CTC1 leads to increased levels of 8-oxoguanine, suggesting defective BER in the absence of CST. Combined, our results define an undiscovered function of CST in BER, where it acts as a stimulatory factor to promote efficient genome-wide oxidative repair.
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Affiliation(s)
- Brandon C Wysong
- Department of Biology, School of Science, Indiana University, Indianapolis, IN, USA
| | - P Logan Schuck
- Department of Biological Sciences, University of South Carolina, Columbia, USA
| | - Madhumita Sridharan
- Department of Biology, School of Science, Indiana University, Indianapolis, IN, USA
| | - Sophie Carrison
- Department of Biology, School of Science, Indiana University, Indianapolis, IN, USA
| | - Yuichihiro Murakami
- Department of Biology, School of Science, Indiana University, Indianapolis, IN, USA
| | - Lata Balakrishnan
- Department of Biology, School of Science, Indiana University, Indianapolis, IN, USA.
| | - Jason A Stewart
- Department of Biological Sciences, University of South Carolina, Columbia, USA; Department of Biology, Western Kentucky University, Bowling Green, KY, USA.
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2
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Wen C, Wang G, Yang L, Chen T, Liu H, Gong W. Structural Basis for C2'-methoxy Recognition by DNA Polymerases and Function Improvement. J Mol Biol 2024; 436:168744. [PMID: 39147125 DOI: 10.1016/j.jmb.2024.168744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2024] [Revised: 07/26/2024] [Accepted: 08/08/2024] [Indexed: 08/17/2024]
Abstract
DNA modified with C2'-methoxy (C2'-OMe) greatly enhances its resistance to nucleases, which is beneficial for the half-life of aptamers and DNA nanomaterials. Although the unnatural DNA polymerases capable of incorporating C2'-OMe modified nucleoside monophosphates (C2'-OMe-NMPs) were engineered via directed evolution, the detailed molecular mechanism by which an evolved DNA polymerase recognizes C2'-OMe-NTPs remains poorly understood. Here, we present the crystal structures of the evolved Stoffel fragment of Taq DNA polymerase SFM4-3 processing the C2'-OMe-GTP in different states. Our results reveal the structural basis for recognition of C2'-methoxy by SFM4-3. Based on the analysis of other mutated residues in SFM4-3, a new Stoffel fragment variant with faster catalytic rate and stronger inhibitor-resistance was obtained. In addition, the capture of a novel pre-insertion co-existing with template 5'-overhang stacking conformation provides insight into the catalytic mechanism of Taq DNA polymerase.
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Affiliation(s)
- Chongzheng Wen
- Division of Biological Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230027, PR China
| | - Guangyuan Wang
- MOE International Joint Research Laboratory on Synthetic Biology and Medicines, School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, PR China
| | - Lin Yang
- Division of Biological Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230027, PR China
| | - Tingjian Chen
- MOE International Joint Research Laboratory on Synthetic Biology and Medicines, School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, PR China.
| | - Haiping Liu
- Division of Biological Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230027, PR China.
| | - Weimin Gong
- Division of Biological Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230027, PR China.
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3
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Zhao W, Hussen AS, Freudenthal BD, Suo Z, Zhao L. Mitochondrial transcription factor A (TFAM) has 5'-deoxyribose phosphate lyase activity in vitro. DNA Repair (Amst) 2024; 137:103666. [PMID: 38492429 PMCID: PMC11056281 DOI: 10.1016/j.dnarep.2024.103666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 02/16/2024] [Accepted: 03/01/2024] [Indexed: 03/18/2024]
Abstract
Mitochondrial DNA (mtDNA) plays a key role in mitochondrial and cellular functions. mtDNA is maintained by active DNA turnover and base excision repair (BER). In BER, one of the toxic repair intermediates is 5'-deoxyribose phosphate (5'dRp). Human mitochondrial DNA polymerase γ has weak dRp lyase activities, and another known dRp lyase in the nucleus, human DNA polymerase β, can also localize to mitochondria in certain cell and tissue types. Nonetheless, whether additional proteins have the ability to remove 5'dRp in mitochondria remains unknown. Our prior work on the AP lyase activity of mitochondrial transcription factor A (TFAM) has prompted us to examine its ability to remove 5'dRp residues in vitro. TFAM is the primary DNA-packaging factor in human mitochondria and interacts with mitochondrial DNA extensively. Our data demonstrate that TFAM has the dRp lyase activity with different DNA substrates. Under single-turnover conditions, TFAM removes 5'dRp residues at a rate comparable to that of DNA polymerase (pol) β, albeit slower than that of pol λ. Among the three proteins examined, pol λ shows the highest single-turnover rates in dRp lyase reactions. The catalytic effect of TFAM is facilitated by lysine residues of TFAM via Schiff base chemistry, as evidenced by the observation of dRp-lysine adducts in mass spectrometry experiments. The catalytic effect of TFAM observed here is analogous to the AP lyase activity of TFAM reported previously. Together, these results suggest a potential role of TFAM in preventing the accumulation of toxic DNA repair intermediates.
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Affiliation(s)
- Wenxin Zhao
- Department of Chemistry, University of California, Riverside, Riverside, CA 92521, United States
| | - Adil S Hussen
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS 66160, United States
| | - Bret D Freudenthal
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS 66160, United States; Department of Cancer Biology, University of Kansas Medical Center, Kansas City, KS 66160, United States; University of Kansas Cancer Center, Kansas City, KS 66160, United States
| | - Zucai Suo
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL 32306, United States
| | - Linlin Zhao
- Department of Chemistry, University of California, Riverside, Riverside, CA 92521, United States; Environmental Toxicology Graduate Program, University of California, Riverside, Riverside, CA 92521, United States.
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4
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Chu WT, Suo Z, Wang J. Three-metal ion mechanism of cross-linked and uncross-linked DNA polymerase β: A theoretical study. J Chem Phys 2024; 160:155101. [PMID: 38619457 DOI: 10.1063/5.0200109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Accepted: 03/28/2024] [Indexed: 04/16/2024] Open
Abstract
In our recent publication, we have proposed a revised base excision repair pathway in which DNA polymerase β (Polβ) catalyzes Schiff base formation prior to the gap-filling DNA synthesis followed by β-elimination. In addition, the polymerase activity of Polβ employs the "three-metal ion mechanism" instead of the long-standing "two-metal ion mechanism" to catalyze phosphodiester bond formation based on the fact derived from time-resolved x-ray crystallography that a third Mg2+ was captured in the polymerase active site after the chemical reaction was initiated. In this study, we develop the models of the uncross-linked and cross-linked Polβ complexes and investigate the "three-metal ion mechanism" vs the "two-metal ion mechanism" by using the quantum mechanics/molecular mechanics molecular dynamics simulations. Our results suggest that the presence of the third Mg2+ ion stabilizes the reaction-state structures, strengthens correct nucleotide binding, and accelerates phosphodiester bond formation. The improved understanding of Polβ's catalytic mechanism provides valuable insights into DNA replication and damage repair.
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Affiliation(s)
- Wen-Ting Chu
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China
| | - Zucai Suo
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, Florida 32306, USA
| | - Jin Wang
- Department of Chemistry & Physics, State University of New York at Stony Brook, Stony Brook, New York 11794, USA
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Kladova OA, Tyugashev TE, Yakimov DV, Mikushina ES, Novopashina DS, Kuznetsov NA, Kuznetsova AA. The Impact of SNP-Induced Amino Acid Substitutions L19P and G66R in the dRP-Lyase Domain of Human DNA Polymerase β on Enzyme Activities. Int J Mol Sci 2024; 25:4182. [PMID: 38673769 PMCID: PMC11050361 DOI: 10.3390/ijms25084182] [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: 03/05/2024] [Revised: 04/08/2024] [Accepted: 04/08/2024] [Indexed: 04/28/2024] Open
Abstract
Base excision repair (BER), which involves the sequential activity of DNA glycosylases, apurinic/apyrimidinic endonucleases, DNA polymerases, and DNA ligases, is one of the enzymatic systems that preserve the integrity of the genome. Normal BER is effective, but due to single-nucleotide polymorphisms (SNPs), the enzymes themselves-whose main function is to identify and eliminate damaged bases-can undergo amino acid changes. One of the enzymes in BER is DNA polymerase β (Polβ), whose function is to fill gaps in DNA. SNPs can significantly affect the catalytic activity of an enzyme by causing an amino acid substitution. In this work, pre-steady-state kinetic analyses and molecular dynamics simulations were used to examine the activity of naturally occurring variants of Polβ that have the substitutions L19P and G66R in the dRP-lyase domain. Despite the substantial distance between the dRP-lyase domain and the nucleotidyltransferase active site, it was found that the capacity to form a complex with DNA and with an incoming dNTP is significantly altered by these substitutions. Therefore, the lower activity of the tested polymorphic variants may be associated with a greater number of unrepaired DNA lesions.
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Affiliation(s)
- Olga A. Kladova
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090, Russia (N.A.K.)
| | - Timofey E. Tyugashev
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090, Russia (N.A.K.)
| | - Denis V. Yakimov
- Department of Natural Sciences, Novosibirsk State University, Novosibirsk 630090, Russia
| | - Elena S. Mikushina
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090, Russia (N.A.K.)
| | - Daria S. Novopashina
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090, Russia (N.A.K.)
| | - Nikita A. Kuznetsov
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090, Russia (N.A.K.)
- Department of Natural Sciences, Novosibirsk State University, Novosibirsk 630090, Russia
| | - Aleksandra A. Kuznetsova
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090, Russia (N.A.K.)
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6
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Zhao W, Xu W, Tang J, Kaushik S, Chang CEA, Zhao L. Key Amino Acid Residues of Mitochondrial Transcription Factor A Synergize with Abasic (AP) Site Dynamics To Facilitate AP-Lyase Reactions. ACS Chem Biol 2023; 18:1168-1179. [PMID: 36930463 PMCID: PMC10198963 DOI: 10.1021/acschembio.3c00047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Abstract
Human mitochondrial DNA (mtDNA) encodes 37 essential genes and plays a critical role in mitochondrial and cellular functions. mtDNA is susceptible to damage by endogenous and exogenous chemicals. Damaged mtDNA molecules are counteracted by the redundancy, repair, and degradation of mtDNA. In response to difficult-to-repair or excessive amounts of DNA lesions, mtDNA degradation is a crucial mitochondrial genome maintenance mechanism. Nevertheless, the molecular basis of mtDNA degradation remains incompletely understood. Recently, mitochondrial transcription factor A (TFAM) has emerged as a factor in degrading damaged mtDNA containing abasic (AP) sites. TFAM has AP-lyase activity, which cleaves DNA at AP sites. Human TFAM and its homologs contain a higher abundance of Glu than that of the proteome. To decipher the role of Glu in TFAM-catalyzed AP-DNA cleavage, we constructed TFAM variants and used biochemical assays, kinetic simulations, and molecular dynamics (MD) simulations to probe the functional importance of E187 near a key residue K186. Our previous studies showed that K186 is a primary residue to cleave AP-DNA via Schiff base chemistry. Here, we demonstrate that E187 facilitates β-elimination, key to AP-DNA strand scission. MD simulations showed that extrahelical confirmation of the AP lesion and the flexibility of E187 in TFAM-DNA complexes facilitate AP-lyase reactions. Together, highly abundant Lys and Glu residues in TFAM promote AP-DNA strand scission, supporting the role of TFAM in AP-DNA turnover and implying the breadth of this process across different species.
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Affiliation(s)
- Wenxin Zhao
- Department of Chemistry, University of California, Riverside, Riverside, California, 92521, United States
| | - Wenyan Xu
- Department of Chemistry, University of California, Riverside, Riverside, California, 92521, United States
| | - Jin Tang
- Department of Chemistry, University of California, Riverside, Riverside, California, 92521, United States
| | - Shivansh Kaushik
- Department of Chemistry, University of California, Riverside, Riverside, California, 92521, United States
| | - Chia-En A. Chang
- Department of Chemistry, University of California, Riverside, Riverside, California, 92521, United States
- Environmental Toxicology Graduate Program, University of California, Riverside, Riverside, California, 92521, United States
| | - Linlin Zhao
- Department of Chemistry, University of California, Riverside, Riverside, California, 92521, United States
- Environmental Toxicology Graduate Program, University of California, Riverside, Riverside, California, 92521, United States
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7
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Chang C, Zhou G, Gao Y. In crystallo observation of active site dynamics and transient metal ion binding within DNA polymerases. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2023; 10:034702. [PMID: 37333512 PMCID: PMC10275647 DOI: 10.1063/4.0000187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 05/31/2023] [Indexed: 06/20/2023]
Abstract
DNA polymerases are the enzymatic catalysts that synthesize DNA during DNA replication and repair. Kinetic studies and x-ray crystallography have uncovered the overall kinetic pathway and led to a two-metal-ion dependent catalytic mechanism. Diffusion-based time-resolved crystallography has permitted the visualization of the catalytic reaction at atomic resolution and made it possible to capture transient events and metal ion binding that have eluded static polymerase structures. This review discusses past static structures and recent time-resolved structures that emphasize the crucial importance of primer alignment and different metal ions binding during catalysis and substrate discrimination.
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Affiliation(s)
| | | | - Yang Gao
- Author to whom correspondence should be addressed:. Tel.: +1 (713) 348-2619
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8
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Bakman AS, Kuznetsova AA, Yanshole LV, Ishchenko AA, Saparbaev M, Fedorova OS, Kuznetsov NA. Fluorescently labeled human apurinic/apyrimidinic endonuclease APE1 reveals effects of DNA polymerase β on the APE1-DNA interaction. DNA Repair (Amst) 2023; 123:103450. [PMID: 36689867 DOI: 10.1016/j.dnarep.2023.103450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 12/26/2022] [Accepted: 01/09/2023] [Indexed: 01/15/2023]
Abstract
The base excision repair (BER) pathway involves sequential action of DNA glycosylases and apurinic/apyrimidinic (AP) endonucleases to incise damaged DNA and prepare DNA termini for incorporation of a correct nucleotide by DNA polymerases. It has been suggested that the enzymatic steps in BER include recognition of a product-enzyme complex by the next enzyme in the pathway, resulting in the "passing-the-baton" model of transfer of DNA intermediates between enzymes. To verify this model, in this work, we aimed to create a suitable experimental system. We prepared APE1 site-specifically labeled with a fluorescent reporter that is sensitive to stages of APE1-DNA binding, of formation of the catalytic complex, and of subsequent dissociation of the enzyme-product complex. Interactions of the labeled APE1 with various model DNA substrates (containing an abasic site) of varied lengths revealed that the enzyme remains mostly in complex with the DNA product. By means of the fluorescently labeled APE1 in combination with a stopped-flow fluorescence assay, it was found that Polβ stimulates both i) APE1 binding to an abasic-site-containing DNA duplex with the formation of a catalytically competent complex and ii) the dissociation of APE1 from its product. These findings confirm DNA-mediated coordination of APE1 and Polβ activities and suggest that Polβ is the key trigger of the DNA transfer between the enzymes participating in initial steps of BER.
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Affiliation(s)
- Artemiy S Bakman
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences (SB RAS), 8 Prospekt Akad. Lavrentyeva, Novosibirsk 630090, Russia
| | - Aleksandra A Kuznetsova
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences (SB RAS), 8 Prospekt Akad. Lavrentyeva, Novosibirsk 630090, Russia
| | - Lyudmila V Yanshole
- International Tomography Center SB RAS, 3a Institutskaya Str., Novosibirsk 630090, Russia
| | - Alexander A Ishchenko
- Group "Mechanisms of DNA Repair and Carcinogenesis", Gustave Roussy Cancer Campus, CNRS UMR9019, Université Paris-Saclay, 94805 Villejuif, France
| | - Murat Saparbaev
- Group "Mechanisms of DNA Repair and Carcinogenesis", Gustave Roussy Cancer Campus, CNRS UMR9019, Université Paris-Saclay, 94805 Villejuif, France; NCJSC "Al-Farabi Kazakh National University" Almaty, Kazakhstan
| | - Olga S Fedorova
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences (SB RAS), 8 Prospekt Akad. Lavrentyeva, Novosibirsk 630090, Russia
| | - Nikita A Kuznetsov
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences (SB RAS), 8 Prospekt Akad. Lavrentyeva, Novosibirsk 630090, Russia; Department of Natural Sciences, Novosibirsk State University, 2 Pirogova Str., Novosibirsk 630090, Russia.
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9
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Abdullah MAF, McWhirter SM, Suo Z. Modulation of Kinase Activities In Vitro by Hepatitis C Virus Protease NS3/NS4A Mediated-Cleavage of Key Immune Modulator Kinases. Cells 2023; 12:406. [PMID: 36766748 PMCID: PMC9913602 DOI: 10.3390/cells12030406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 01/09/2023] [Accepted: 01/22/2023] [Indexed: 01/26/2023] Open
Abstract
Hepatitis C Virus NS3/NS4A, a serine protease complex, has been found to interact with many host proteins and cause various adverse effects on cellular function and immune response. For example, the cleavage of important immune factors by NS3/NS4A has been suggested as a mechanism for the hepatitis C virus to evade innate immunity. The spectrum of susceptible substrates for NS3/NS4A cleavage certainly includes important immune modulator kinases such as IKKα, IKKβ, IKKε, and TBK1, as demonstrated in this paper. We show that the kinase activities of these four host kinases were transformed in unexpected ways by NS3/NS4A. Treatment with NS3/NS4A caused a significant reduction in the kinase activities of both IKKα and IKKβ, suggesting that HCV might use its NS3/NS4A protease activity to deactivate the NF-κB-associated innate immune responses. In contrast, the kinase activities of both IKKε and TBK1 were enhanced after NS3/NS4A treatment, and more strikingly, the enhancement was more than 10-fold within 20 min of treatment. Our mass spectroscopic results suggested that the cleavage after Cys89 in the kinase domain of IKKε by NS3/NS4A led to their higher kinase activities, and three potential mechanisms were discussed. The observed kinase activity enhancement might facilitate the activation of both IKKε- and TBK1-dependent cellular antiviral pathways, likely contributing to spontaneous clearance of the virus and observed acute HCV infection. After longer than 20 min cleavage, both IKKε- and TBK1 gradually lost their kinase activities and the relevant antiviral pathways were expected to be inactivated, facilitating the establishment of chronic HCV infection.
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Affiliation(s)
| | - Sarah M. McWhirter
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
| | - Zucai Suo
- Department of Biochemistry, The Ohio State University, Columbus, OH 43210, USA
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL 32306, USA
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10
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Weaver TM, Washington MT, Freudenthal BD. New insights into DNA polymerase mechanisms provided by time-lapse crystallography. Curr Opin Struct Biol 2022; 77:102465. [PMID: 36174287 PMCID: PMC9772199 DOI: 10.1016/j.sbi.2022.102465] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 08/15/2022] [Accepted: 08/24/2022] [Indexed: 12/24/2022]
Abstract
DNA polymerases play central roles in DNA replication and repair by catalyzing template-directed nucleotide incorporation. Recently time-lapse X-ray crystallography, which allows one to observe reaction intermediates, has revealed numerous and unexpected mechanistic features of DNA polymerases. In this article, we will examine recent new discoveries that have come from time-lapse crystallography that are currently transforming our understanding of the structural mechanisms used by DNA polymerases. Among these new discoveries are the binding of a third metal ion within the polymerase active site, the mechanisms of translocation along the DNA, the presence of new fidelity checkpoints, a novel pyrophosphatase activity within the active site, and the mechanisms of pyrophosphorolysis.
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Affiliation(s)
- Tyler M Weaver
- Department of Biochemistry and Molecular Biology, Department of Cancer Biology, University of Kansas Medical Center, Kansas City, KS, 66160, USA. https://twitter.com/tylermweaver1
| | - M Todd Washington
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA.
| | - Bret D Freudenthal
- Department of Biochemistry and Molecular Biology, Department of Cancer Biology, University of Kansas Medical Center, Kansas City, KS, 66160, USA.
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