1
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Quillin A, Arnould B, Knutson SD, Heemstra JM. Spatial Visualization of A-to-I Editing in Cells Using Endonuclease V Immunostaining Assay (EndoVIA). ACS CENTRAL SCIENCE 2024; 10:1396-1405. [PMID: 39071059 PMCID: PMC11273454 DOI: 10.1021/acscentsci.4c00444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 06/19/2024] [Accepted: 06/21/2024] [Indexed: 07/30/2024]
Abstract
Adenosine-to-inosine (A-to-I) editing is one of the most widespread post-transcriptional RNA modifications and is catalyzed by adenosine deaminases acting on RNA (ADARs). Varying across tissue types, A-to-I editing is essential for numerous biological functions, and dysregulation leads to autoimmune and neurological disorders, as well as cancer. Recent evidence has also revealed a link between RNA localization and A-to-I editing, yet understanding of the mechanisms underlying this relationship and its biological impact remains limited. Current methods rely primarily on in vitro characterization of extracted RNA that ultimately erases subcellular localization and cell-to-cell heterogeneity. To address these challenges, we have repurposed endonuclease V (EndoV), a magnesium-dependent ribonuclease that cleaves inosine bases in edited RNA, to selectively bind and detect A-to-I edited RNA in cells. The work herein introduces an endonuclease V immunostaining assay (EndoVIA), a workflow that provides spatial visualization of edited transcripts, enables rapid quantification of overall inosine abundance, and maps the landscape of A-to-I editing within the transcriptome at the nanoscopic level.
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Affiliation(s)
- Alexandria
L. Quillin
- Department
of Chemistry, Washington University in St.
Louis, St. Louis, Missouri 63130, United States
| | - Benoît Arnould
- Department
of Chemistry, Washington University in St.
Louis, St. Louis, Missouri 63130, United States
| | - Steve D. Knutson
- Merck
Center for Catalysis, Princeton University, Princeton, New Jersey 08544, United States
- Department
of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Jennifer M. Heemstra
- Department
of Chemistry, Washington University in St.
Louis, St. Louis, Missouri 63130, United States
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2
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Mitsuoka K, Kim JI, Yoshida A, Matsumoto A, Aoki-Shioi N, Iwai S, Kuraoka I. Base preference for inosine 3'-riboendonuclease activity of human endonuclease V: implications for cleavage of poly-A tails containing inosine. Sci Rep 2024; 14:14973. [PMID: 38951658 PMCID: PMC11217400 DOI: 10.1038/s41598-024-65814-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 06/24/2024] [Indexed: 07/03/2024] Open
Abstract
Deamination of bases is a form of DNA damage that occurs spontaneously via the hydrolysis and nitrosation of living cells, generating hypoxanthine from adenine. E. coli endonuclease V (eEndoV) cleaves hypoxanthine-containing double-stranded DNA, whereas human endonuclease V (hEndoV) cleaves hypoxanthine-containing RNA; however, hEndoV in vivo function remains unclear. To date, hEndoV has only been examined using hypoxanthine, because it binds closely to the base located at the cleavage site. Here, we examined whether hEndoV cleaves other lesions (e.g., AP site, 6-methyladenine, xanthine) to reveal its function and whether 2'-nucleoside modification affects its cleavage activity. We observed that hEndoV is hypoxanthine-specific; its activity was the highest with 2'-OH modification in ribose. The cleavage activity of hEndoV was compared based on its base sequence. We observed that it has specificity for adenine located on the 3'-end of hypoxanthine at the cleavage site, both before and after cleavage. These data suggest that hEndoV recognizes and cleaves the inosine generated on the poly A tail to maintain RNA quality. Our results provide mechanistic insight into the role of hEndoV in vivo.
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Affiliation(s)
- Kazuma Mitsuoka
- Department of Chemistry, Faculty of Science, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka, 814-0180, Japan
| | - Jung In Kim
- Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka, 560-8531, Japan
| | - Aya Yoshida
- Department of Chemistry, Faculty of Science, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka, 814-0180, Japan
| | - Akane Matsumoto
- Department of Chemistry, Faculty of Science, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka, 814-0180, Japan
| | - Narumi Aoki-Shioi
- Department of Chemistry, Faculty of Science, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka, 814-0180, Japan
| | - Shigenori Iwai
- Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka, 560-8531, Japan
| | - Isao Kuraoka
- Department of Chemistry, Faculty of Science, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka, 814-0180, Japan.
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3
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Lazzarotto CR, Katta V, Li Y, Urbina E, Lee G, Tsai SQ. CHANGE-seq-BE enables simultaneously sensitive and unbiased in vitro profiling of base editor genome-wide activity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.28.586621. [PMID: 38585919 PMCID: PMC10996588 DOI: 10.1101/2024.03.28.586621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Base editors ( BE ) enable programmable conversion of nucleotides in genomic DNA without double-stranded breaks and have substantial promise to become new transformative genome editing medicines. Sensitive and unbiased detection of base editor off-target effects is important for identifying safety risks unique to base editors and translation to human therapeutics, as well as accurate use in life sciences research. However, current methods for understanding the global activities of base editors have limitations in terms of sensitivity or bias. Here we present CHANGE-seq-BE, a novel method to directly assess the off-target profile of base editors that is simultaneously sensitive and unbiased. CHANGE-seq-BE is based on the principle of selective sequencing of adenine base editor modified genomic DNA in vitro , and provides an accessible, rapid, and comprehensive method for identifying genome-wide off-target mutations of base editors.
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4
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Quillin AL, Arnould B, Knutson SD, Heemstra JM. Spatial visualization of A-to-I Editing in cells using Endonuclease V Immunostaining Assay (EndoVIA). BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.04.583344. [PMID: 38496620 PMCID: PMC10942280 DOI: 10.1101/2024.03.04.583344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
Adenosine-to-Inosine (A-to-I) editing is one of the most widespread post-transcriptional RNA modifications and is catalyzed by adenosine deaminases acting on RNA (ADARs). Varying across tissue types, A-to-I editing is essential for numerous biological functions and dysregulation leads to autoimmune and neurological disorders, as well as cancer. Recent evidence has also revealed a link between RNA localization and A-to-I editing, yet understanding of the mechanisms underlying this relationship and its biological impact remains limited. Current methods rely primarily on in vitro characterization of extracted RNA that ultimately erases subcellular localization and cell-to-cell heterogeneity. To address these challenges, we have repurposed Endonuclease V (EndoV), a magnesium dependent ribonuclease that cleaves inosine bases in edited RNA, to selectively bind and detect A-to-I edited RNA in cells. The work herein introduces Endonuclease V Immunostaining Assay (EndoVIA), a workflow that provides spatial visualization of edited transcripts, enables rapid quantification of overall inosine abundance, and maps the landscape of A-to-I editing within the transcriptome at the nanoscopic level.
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5
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Schroader JH, Handley MT, Reddy K. Inosine triphosphate pyrophosphatase: A guardian of the cellular nucleotide pool and potential mediator of RNA function. WILEY INTERDISCIPLINARY REVIEWS. RNA 2023; 14:e1790. [PMID: 37092460 DOI: 10.1002/wrna.1790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 02/10/2023] [Accepted: 03/20/2023] [Indexed: 04/25/2023]
Abstract
Inosine triphosphate pyrophosphatase (ITPase), encoded by the ITPA gene in humans, is an important enzyme that preserves the integrity of cellular nucleotide pools by hydrolyzing the noncanonical purine nucleotides (deoxy)inosine and (deoxy)xanthosine triphosphate into monophosphates and pyrophosphate. Variants in the ITPA gene can cause partial or complete ITPase deficiency. Partial ITPase deficiency is benign but clinically relevant as it is linked to altered drug responses. Complete ITPase deficiency causes a severe multisystem disorder characterized by seizures and encephalopathy that is frequently associated with fatal infantile dilated cardiomyopathy. In the absence of ITPase activity, its substrate noncanonical nucleotides have the potential to accumulate and become aberrantly incorporated into DNA and RNA. Hence, the pathophysiology of ITPase deficiency could arise from metabolic imbalance, altered DNA or RNA regulation, or from a combination of these factors. Here, we review the known functions of ITPase and highlight recent work aimed at determining the molecular basis for ITPA-associated pathogenesis which provides evidence for RNA dysfunction. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA in Disease and Development > RNA in Development.
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Affiliation(s)
- Jacob H Schroader
- The RNA Institute, University at Albany, State University of New York, Albany, New York, USA
- Department of Biological Sciences, University at Albany, State University of New York, Albany, New York, USA
| | - Mark T Handley
- Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Kaalak Reddy
- The RNA Institute, University at Albany, State University of New York, Albany, New York, USA
- Department of Biological Sciences, University at Albany, State University of New York, Albany, New York, USA
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6
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Pagano A, Kunz L, Dittmann A, Araújo SDS, Macovei A, Shridhar Gaonkar S, Sincinelli F, Wazeer H, Balestrazzi A. Changes in Medicago truncatula seed proteome along the rehydration-dehydration cycle highlight new players in the genotoxic stress response. FRONTIERS IN PLANT SCIENCE 2023; 14:1188546. [PMID: 37409306 PMCID: PMC10319343 DOI: 10.3389/fpls.2023.1188546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 05/24/2023] [Indexed: 07/07/2023]
Abstract
Introduction Several molecular aspects underlying the seed response to priming and the resulting vigor profile are still poorly understood. Mechanisms involved in genome maintenance deserve attention since the balance between stimulation of germination and DNA damage accumulation versus active repair is a key determinant for designing successful seed priming protocols. Methods Changes in the Medicago truncatula seed proteome were investigated in this study, using discovery mass spectrometry and label-free quantification, along the rehydration-dehydration cycle of a standard vigorization treatment (hydropriming plus dry-back), and during post-priming imbibition. Resuts and discussion From 2056 to 2190 proteins were detected in each pairwise comparison, among which six were differentially accumulated and 36 were detected only in one condition. The following proteins were selected for further investigation: MtDRP2B (DYNAMIN-RELATED PROTEIN), MtTRXm4 (THIOREDOXIN m4), and MtASPG1 (ASPARTIC PROTEASE IN GUARD CELL 1) showing changes in seeds under dehydration stress; MtITPA (INOSINE TRIPHOSPHATE PYROPHOSPHORYLASE), MtABA2 (ABSCISIC ACID DEFICIENT 2), MtRS2Z32 (SERINE/ARGININE-RICH SPLICING FACTOR RS2Z32), and MtAQR (RNA HELICASE AQUARIUS) that were differentially regulated during post-priming imbibition. Changes in the corresponding transcript levels were assessed by qRT-PCR. In animal cells, ITPA hydrolyses 2'-deoxyinosine triphosphate and other inosine nucleotides, preventing genotoxic damage. A proof of concept was performed by imbibing primed and control M. truncatula seeds in presence/absence of 20 mM 2'-deoxyinosine (dI). Results from comet assay highlighted the ability of primed seeds to cope with dI-induced genotoxic damage. The seed repair response was assessed by monitoring the expression profiles of MtAAG (ALKYL-ADENINE DNA GLYCOSILASE) and MtEndoV (ENDONUCLEASE V) genes that participate in the repair of the mismatched I:T pair in BER (base excision repair) and AER (alternative excision repair) pathways, respectively.
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Affiliation(s)
- Andrea Pagano
- Department of Biology and Biotechnology ‘L. Spallanzani’, University of Pavia, Pavia, Italy
| | - Laura Kunz
- Functional Genomics Center Zurich (FGCZ), University of Zurich/Eidgenossische Technische Hochschule (ETH) Zurich, Zurich, Switzerland
| | - Antje Dittmann
- Functional Genomics Center Zurich (FGCZ), University of Zurich/Eidgenossische Technische Hochschule (ETH) Zurich, Zurich, Switzerland
| | - Susana De Sousa Araújo
- Association BLC3 - Campus of Technology and Innovation, Centre BIO R&D Unit | North Delegation, Macedo de Cavaleiros, Portugal
| | - Anca Macovei
- Department of Biology and Biotechnology ‘L. Spallanzani’, University of Pavia, Pavia, Italy
- National Biodiversity Future Center (NBFC), Palermo, Italy
| | | | - Federico Sincinelli
- Department of Biology and Biotechnology ‘L. Spallanzani’, University of Pavia, Pavia, Italy
| | - Hisham Wazeer
- Department of Biology and Biotechnology ‘L. Spallanzani’, University of Pavia, Pavia, Italy
| | - Alma Balestrazzi
- Department of Biology and Biotechnology ‘L. Spallanzani’, University of Pavia, Pavia, Italy
- National Biodiversity Future Center (NBFC), Palermo, Italy
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7
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Seo D, Koh B, Eom GE, Kim HW, Kim S. A dual gene-specific mutator system installs all transition mutations at similar frequencies in vivo. Nucleic Acids Res 2023; 51:e59. [PMID: 37070179 PMCID: PMC10250238 DOI: 10.1093/nar/gkad266] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 03/31/2023] [Indexed: 04/19/2023] Open
Abstract
Targeted in vivo hypermutation accelerates directed evolution of proteins through concurrent DNA diversification and selection. Although systems employing a fusion protein of a nucleobase deaminase and T7 RNA polymerase present gene-specific targeting, their mutational spectra have been limited to exclusive or dominant C:G→T:A mutations. Here we describe eMutaT7transition, a new gene-specific hypermutation system, that installs all transition mutations (C:G→T:A and A:T→G:C) at comparable frequencies. By using two mutator proteins in which two efficient deaminases, PmCDA1 and TadA-8e, are separately fused to T7 RNA polymerase, we obtained similar numbers of C:G→T:A and A:T→G:C substitutions at a sufficiently high frequency (∼6.7 substitutions in 1.3 kb gene during 80-h in vivo mutagenesis). Through eMutaT7transition-mediated TEM-1 evolution for antibiotic resistance, we generated many mutations found in clinical isolates. Overall, with a high mutation frequency and wider mutational spectrum, eMutaT7transition is a potential first-line method for gene-specific in vivo hypermutation.
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Affiliation(s)
- Daeje Seo
- Department of Chemistry, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Bonghyun Koh
- Department of Chemistry, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Ga-eul Eom
- Department of Chemistry, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Hye Won Kim
- Department of Chemistry, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Seokhee Kim
- Department of Chemistry, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
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8
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Zheng X, Chen D, Zhao Y, Dai X, You C. Development of an Endonuclease V-Assisted Analytical Method for Sequencing Analysis of Deoxyinosine in DNA. Anal Chem 2022; 94:11627-11632. [PMID: 35942621 DOI: 10.1021/acs.analchem.2c02126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Deoxyinosine (dI) is a highly mutagenic lesion that preferentially pairs with deoxycytidine during replication, which may induce A to G transition and ultimately contribute to carcinogenesis. Therefore, finding the site of dI modification in DNA is of great value for both basic research and clinical applications. Herein, we developed a novel method to sequence the dI modification site in DNA, which utilizes endonuclease V (EndoV)-dependent deamination repair to specifically label the modification site with biotin-14-dATP that allows the affinity enrichment of dI-bearing DNA for sequencing. We have achieved efficient determination of the location of the modified nucleotide in dI-bearing plasmid DNA with the assistance of EndoV-dependent deamination repair. We have also successfully applied this approach to locate the dI modification sites in the mitochondrial DNA of human cells. Our method should be generally applicable for genome-wide sequencing analysis of dI modifications in living organisms.
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Affiliation(s)
- Xiaofang Zheng
- Molecular Science and Biomedicine Laboratory, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan Provincial Key Laboratory of Biomacromolecular Chemical Biology, Hunan University, Changsha 410082, China
| | - Di Chen
- Molecular Science and Biomedicine Laboratory, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan Provincial Key Laboratory of Biomacromolecular Chemical Biology, Hunan University, Changsha 410082, China
| | - Yingqi Zhao
- Molecular Science and Biomedicine Laboratory, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan Provincial Key Laboratory of Biomacromolecular Chemical Biology, Hunan University, Changsha 410082, China
| | - Xiaoxia Dai
- Molecular Science and Biomedicine Laboratory, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan Provincial Key Laboratory of Biomacromolecular Chemical Biology, Hunan University, Changsha 410082, China
| | - Changjun You
- Molecular Science and Biomedicine Laboratory, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan Provincial Key Laboratory of Biomacromolecular Chemical Biology, Hunan University, Changsha 410082, China
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9
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Dutta N, Deb I, Sarzynska J, Lahiri A. Inosine and its methyl derivatives: Occurrence, biogenesis, and function in RNA. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2022; 169-170:21-52. [PMID: 35065168 DOI: 10.1016/j.pbiomolbio.2022.01.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 12/11/2021] [Accepted: 01/11/2022] [Indexed: 05/21/2023]
Abstract
Inosine is one of the most common post-transcriptional modifications. Since its discovery, it has been noted for its ability to contribute to non-Watson-Crick interactions within RNA. Rapidly accumulating evidence points to the widespread generation of inosine through hydrolytic deamination of adenosine to inosine by different classes of adenosine deaminases. Three naturally occurring methyl derivatives of inosine, i.e., 1-methylinosine, 2'-O-methylinosine and 1,2'-O-dimethylinosine are currently reported in RNA modification databases. These modifications are expected to lead to changes in the structure, folding, dynamics, stability and functions of RNA. The importance of the modifications is indicated by the strong conservation of the modifying enzymes across organisms. The structure, binding and catalytic mechanism of the adenosine deaminases have been well-studied, but the underlying mechanism of the catalytic reaction is not very clear yet. Here we extensively review the existing data on the occurrence, biogenesis and functions of inosine and its methyl derivatives in RNA. We also included the structural and thermodynamic aspects of these modifications in our review to provide a detailed and integrated discussion on the consequences of A-to-I editing in RNA and the contribution of different structural and thermodynamic studies in understanding its role in RNA. We also highlight the importance of further studies for a better understanding of the mechanisms of the different classes of deamination reactions. Further investigation of the structural and thermodynamic consequences and functions of these modifications in RNA should provide more useful information about their role in different diseases.
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Affiliation(s)
- Nivedita Dutta
- Department of Biophysics, Molecular Biology and Bioinformatics, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata, 700009, West Bengal, India
| | - Indrajit Deb
- Department of Biophysics, Molecular Biology and Bioinformatics, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata, 700009, West Bengal, India
| | - Joanna Sarzynska
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704, Poznan, Poland
| | - Ansuman Lahiri
- Department of Biophysics, Molecular Biology and Bioinformatics, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata, 700009, West Bengal, India.
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10
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Kawada T, Kino K, Tokorodani K, Anabuki R, Morikawa M, Kobayashi T, Ohara K, Ohshima T, Miyazawa H. Analysis of nucleotide insertion opposite urea and translesion synthesis across urea by DNA polymerases. Genes Environ 2022; 44:7. [PMID: 35168664 PMCID: PMC8845263 DOI: 10.1186/s41021-022-00236-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 02/01/2022] [Indexed: 11/10/2022] Open
Abstract
Abstract Urea (Ua) is produced in DNA as the result of oxidative damage to thymine and guanine. It was previously reported that Klenow fragment (Kf) exo− incorporated dATP opposite Ua, and that DNA polymerase β was blocked by Ua. We report here the following nucleotide incorporations opposite Ua by various DNA polymerases: DNA polymerase α, dATP and dGTP (dATP > dGTP); DNA polymerase δ, dATP; DNA polymerase ζ, dATP; Kf exo−, dATP; Sulfolobus solfataricus P2 DNA polymerase IV (Dpo4), dGTP and dATP (dGTP > dATP); and DNA polymerase η, dCTP, dGTP, dATP, and dTTP (dCTP > dGTP > dATP > dTTP). DNA polymerases β and ε were blocked by Ua. Elongation by DNA polymerases δ and ζ stopped after inserting dATP opposite Ua. Importantly, the elongation efficiency to full-length beyond Ua using DNA polymerase η and Dpo4 were almost the same as that of natural DNA. Graphical abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s41021-022-00236-3.
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Affiliation(s)
- Taishu Kawada
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, 1314-1 Shido, Sanuki, Kagawa, 769-2193, Japan
| | - Katsuhito Kino
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, 1314-1 Shido, Sanuki, Kagawa, 769-2193, Japan.
| | - Kyousuke Tokorodani
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, 1314-1 Shido, Sanuki, Kagawa, 769-2193, Japan
| | - Ryuto Anabuki
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, 1314-1 Shido, Sanuki, Kagawa, 769-2193, Japan
| | - Masayuki Morikawa
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, 1314-1 Shido, Sanuki, Kagawa, 769-2193, Japan
| | - Takanobu Kobayashi
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, 1314-1 Shido, Sanuki, Kagawa, 769-2193, Japan
| | - Kazuaki Ohara
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, 1314-1 Shido, Sanuki, Kagawa, 769-2193, Japan
| | - Takayuki Ohshima
- Faculty of Science and Engineering, Tokushima Bunri University, 1314-1 Shido, Sanuki, Kagawa, 769-2193, Japan
| | - Hiroshi Miyazawa
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, 1314-1 Shido, Sanuki, Kagawa, 769-2193, Japan
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11
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Endo M, Kim JI, Shioi NA, Iwai S, Kuraoka I. Arabidopsis thaliana endonuclease V is a ribonuclease specific for inosine-containing single-stranded RNA. Open Biol 2021; 11:210148. [PMID: 34665969 PMCID: PMC8526164 DOI: 10.1098/rsob.210148] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Endonuclease V is highly conserved, both structurally and functionally, from bacteria to humans, and it cleaves the deoxyinosine-containing double-stranded DNA in Escherichia coli, whereas in Homo sapiens it catalyses the inosine-containing single-stranded RNA. Thus, deoxyinosine and inosine are unexpectedly produced by the deamination reactions of adenine in DNA and RNA, respectively. Moreover, adenosine-to-inosine (A-to-I) RNA editing is carried out by adenosine deaminase acting on dsRNA (ADARs). We focused on Arabidopsis thaliana endonuclease V (AtEndoV) activity exhibiting variations in DNA or RNA substrate specificities. Since no ADAR was observed for A-to-I editing in A. thaliana, the possibility of inosine generation by A-to-I editing can be ruled out. Purified AtEndoV protein cleaved the second and third phosphodiester bonds, 3' to inosine in single-strand RNA, at a low reaction temperature of 20-25°C, whereas the AtEndoV (Y100A) protein bearing a mutation in substrate recognition sites did not cleave these bonds. Furthermore, AtEndoV, similar to human EndoV, prefers RNA substrates over DNA substrates, and it could not cleave the inosine-containing double-stranded RNA. Thus, we propose the possibility that AtEndoV functions as an RNA substrate containing inosine induced by RNA damage, and not by A-to-I RNA editing in vivo.
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Affiliation(s)
- Megumi Endo
- Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
| | - Jung In Kim
- Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
| | - Narumi Aoki Shioi
- Department of Chemistry, Faculty of Science, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka 814-0180, Japan
| | - Shigenori Iwai
- Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
| | - Isao Kuraoka
- Department of Chemistry, Faculty of Science, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka 814-0180, Japan
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12
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Structural basis for recognition of distinct deaminated DNA lesions by endonuclease Q. Proc Natl Acad Sci U S A 2021; 118:2021120118. [PMID: 33658373 DOI: 10.1073/pnas.2021120118] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Spontaneous deamination of DNA cytosine and adenine into uracil and hypoxanthine, respectively, causes C to T and A to G transition mutations if left unrepaired. Endonuclease Q (EndoQ) initiates the repair of these premutagenic DNA lesions in prokaryotes by cleaving the phosphodiester backbone 5' of either uracil or hypoxanthine bases or an apurinic/apyrimidinic (AP) lesion generated by the excision of these damaged bases. To understand how EndoQ achieves selectivity toward these structurally diverse substrates without cleaving undamaged DNA, we determined the crystal structures of Pyrococcus furiosus EndoQ bound to DNA substrates containing uracil, hypoxanthine, or an AP lesion. The structures show that substrate engagement by EndoQ depends both on a highly distorted conformation of the DNA backbone, in which the target nucleotide is extruded out of the helix, and direct hydrogen bonds with the deaminated bases. A concerted swing motion of the zinc-binding and C-terminal helical domains of EndoQ toward its catalytic domain allows the enzyme to clamp down on a sharply bent DNA substrate, shaping a deep active-site pocket that accommodates the extruded deaminated base. Within this pocket, uracil and hypoxanthine bases interact with distinct sets of amino acid residues, with positioning mediated by an essential magnesium ion. The EndoQ-DNA complex structures reveal a unique mode of damaged DNA recognition and provide mechanistic insights into the initial step of DNA damage repair by the alternative excision repair pathway. Furthermore, we demonstrate that the unique activity of EndoQ is useful for studying DNA deamination and repair in mammalian systems.
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13
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Evolutionary Origins of DNA Repair Pathways: Role of Oxygen Catastrophe in the Emergence of DNA Glycosylases. Cells 2021; 10:cells10071591. [PMID: 34202661 PMCID: PMC8307549 DOI: 10.3390/cells10071591] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 06/17/2021] [Accepted: 06/18/2021] [Indexed: 11/23/2022] Open
Abstract
It was proposed that the last universal common ancestor (LUCA) evolved under high temperatures in an oxygen-free environment, similar to those found in deep-sea vents and on volcanic slopes. Therefore, spontaneous DNA decay, such as base loss and cytosine deamination, was the major factor affecting LUCA’s genome integrity. Cosmic radiation due to Earth’s weak magnetic field and alkylating metabolic radicals added to these threats. Here, we propose that ancient forms of life had only two distinct repair mechanisms: versatile apurinic/apyrimidinic (AP) endonucleases to cope with both AP sites and deaminated residues, and enzymes catalyzing the direct reversal of UV and alkylation damage. The absence of uracil–DNA N-glycosylases in some Archaea, together with the presence of an AP endonuclease, which can cleave uracil-containing DNA, suggests that the AP endonuclease-initiated nucleotide incision repair (NIR) pathway evolved independently from DNA glycosylase-mediated base excision repair. NIR may be a relic that appeared in an early thermophilic ancestor to counteract spontaneous DNA damage. We hypothesize that a rise in the oxygen level in the Earth’s atmosphere ~2 Ga triggered the narrow specialization of AP endonucleases and DNA glycosylases to cope efficiently with a widened array of oxidative base damage and complex DNA lesions.
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14
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Schauerte M, Pozhydaieva N, Höfer K. Shaping the Bacterial Epitranscriptome-5'-Terminal and Internal RNA Modifications. Adv Biol (Weinh) 2021; 5:e2100834. [PMID: 34121369 DOI: 10.1002/adbi.202100834] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 05/07/2021] [Indexed: 11/11/2022]
Abstract
All domains of life utilize a diverse set of modified ribonucleotides that can impact the sequence, structure, function, stability, and the fate of RNAs, as well as their interactions with other molecules. Today, more than 160 different RNA modifications are known that decorate the RNA at the 5'-terminus or internal RNA positions. The boost of next-generation sequencing technologies sets the foundation to identify and study the functional role of RNA modifications. The recent advances in the field of RNA modifications reveal a novel regulatory layer between RNA modifications and proteins, which is central to developing a novel concept called "epitranscriptomics." The majority of RNA modifications studies focus on the eukaryotic epitranscriptome. In contrast, RNA modifications in prokaryotes are poorly characterized. This review outlines the current knowledge of the prokaryotic epitranscriptome focusing on mRNA modifications. Here, it is described that several internal and 5'-terminal RNA modifications either present or likely present in prokaryotic mRNA. Thereby, the individual techniques to identify these epitranscriptomic modifications, their writers, readers and erasers, and their proposed functions are explored. Besides that, still unanswered questions in the field of prokaryotic epitranscriptomics are pointed out, and its future perspectives in the dawn of next-generation sequencing technologies are outlined.
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Affiliation(s)
- Maik Schauerte
- Max-Planck-Institute for terrestrial Microbiology, Marburg, Hessen, 35043, Germany
| | - Nadiia Pozhydaieva
- Max-Planck-Institute for terrestrial Microbiology, Marburg, Hessen, 35043, Germany
| | - Katharina Höfer
- Max-Planck-Institute for terrestrial Microbiology, Marburg, Hessen, 35043, Germany
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15
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Knutson SD, Heemstra JM. EndoVIPER-seq for Improved Detection of A-to-I Editing Sites in Cellular RNA. ACTA ACUST UNITED AC 2021; 12:e82. [PMID: 32469473 DOI: 10.1002/cpch.82] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Adenosine to-inosine (A-to-I) RNA editing is a conserved post-transcriptional modification that is critical for a variety of cellular processes. A-to-I editing is widespread in nearly all types of RNA, directly imparting significant global changes in cellular function and behavior. Dysfunctional RNA editing is also implicated in a number of diseases, and A-to-I editing activity is rapidly becoming an important biomarker for early detection of cancer, immune disorders, and neurodegeneration. While millions of sites have been identified, the biological function of the majority of these sites is unknown, and the regulatory mechanisms for controlling editing activity at individual sites is not well understood. Robust detection and mapping of A-to-I editing activity throughout the transcriptome is vital for understanding these properties and how editing affects cellular behavior. However, accurately identifying A-to-I editing sites is challenging because of inherent sampling errors present in RNA-seq. We recently developed Endonuclease V immunoprecipitation enrichment sequencing (EndoVIPER-seq) to directly address this challenge by enrichment of A-to-I edited RNAs prior to sequencing. This protocol outlines how to process cellular RNA, enrich for A-to-I edited transcripts with EndoVIPER pulldown, and prepare libraries suitable for generating RNA-seq data. © 2020 Wiley Periodicals LLC. Basic Protocol 1: mRNA fragmentation and glyoxalation Basic Protocol 2: EndoVIPER pulldown Basic Protocol 3: RNA-seq library preparation and data analysis.
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16
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Gu S, Bodai Z, Cowan QT, Komor AC. Base Editors: Expanding the Types of DNA Damage Products Harnessed for Genome Editing. ACTA ACUST UNITED AC 2021; 1. [PMID: 34368792 DOI: 10.1016/j.ggedit.2021.100005] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Base editors are an innovative addition to the genome editing toolbox that introduced a new genome editing strategy to the field. Instead of using double-stranded DNA breaks, base editors use nucleobase modification chemistry to efficiently and precisely incorporate single nucleotide variants (SNVs) into the genome of living cells. Two classes of DNA base editors currently exist: deoxycytidine deamination-derived editors (CBEs, which facilitate C•G to T•A mutations) and deoxyadenosine deamination-derived base editors (ABEs, which facilitate A•T to G•C mutations). More recently, the development of mitochondrial base editors allowed the introduction of C•G to T•A mutations into mitochondrial DNA as well. Base editors show great potential as therapeutic agents and research tools, and extensive studies have been carried out to improve upon the original base editor constructs to aid researchers in a variety of disciplines. Despite their widespread use, there are few publications that focus on elucidating the biological pathways involved during the processing of base editor intermediates. Because base editors introduce unique types of DNA damage products (a U•G mismatch with a DNA backbone nick for CBEs, and an I•T mismatch with a DNA backbone nick for ABEs) to facilitate genome editing, a deep understanding of the DNA damage repair pathways that facilitate or impede base editing represents an important aspect for the further expansion and improvement of the technologies. Here, we first review canonical deoxyuridine, deoxyinosine, and single-stranded break repair. Then, we discuss how interactions among these different repair processes can lead to different base editing outcomes. Through this review, we hope to promote thoughtful discussions on the DNA repair mechanisms of base editing, as well as help researchers in the improvement of the current base editors and the development of new base editors.
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Affiliation(s)
- Sifeng Gu
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, USA
| | - Zsolt Bodai
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, USA
| | - Quinn T Cowan
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, USA
| | - Alexis C Komor
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, USA
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17
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Structural insights into the bypass of the major deaminated purines by translesion synthesis DNA polymerase. Biochem J 2020; 477:4797-4810. [PMID: 33258913 DOI: 10.1042/bcj20200800] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 11/17/2020] [Accepted: 11/27/2020] [Indexed: 12/22/2022]
Abstract
The exocyclic amines of nucleobases can undergo deamination by various DNA damaging agents such as reactive oxygen species, nitric oxide, and water. The deamination of guanine and adenine generates the promutagenic xanthine and hypoxanthine, respectively. The exocyclic amines of bases in DNA are hydrogen bond donors, while the carbonyl moiety generated by the base deamination acts as hydrogen bond acceptors, which can alter base pairing properties of the purines. Xanthine is known to base pair with both cytosine and thymine, while hypoxanthine predominantly pairs with cytosine to promote A to G mutations. Despite the known promutagenicity of the major deaminated purines, structures of DNA polymerase bypassing these lesions have not been reported. To gain insights into the deaminated-induced mutagenesis, we solved crystal structures of human DNA polymerase η (polη) catalyzing across xanthine and hypoxanthine. In the catalytic site of polη, the deaminated guanine (i.e., xanthine) forms three Watson-Crick-like hydrogen bonds with an incoming dCTP, indicating the O2-enol tautomer of xanthine involves in the base pairing. The formation of the enol tautomer appears to be promoted by the minor groove contact by Gln38 of polη. When hypoxanthine is at the templating position, the deaminated adenine uses its O6-keto tautomer to form two Watson-Crick hydrogen bonds with an incoming dCTP, providing the structural basis for the high promutagenicity of hypoxanthine.
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18
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Lapinaite A, Knott GJ, Palumbo CM, Lin-Shiao E, Richter MF, Zhao KT, Beal PA, Liu DR, Doudna JA. DNA capture by a CRISPR-Cas9-guided adenine base editor. Science 2020; 369:566-571. [PMID: 32732424 DOI: 10.1126/science.abb1390] [Citation(s) in RCA: 103] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 05/27/2020] [Indexed: 12/22/2022]
Abstract
CRISPR-Cas-guided base editors convert A•T to G•C, or C•G to T•A, in cellular DNA for precision genome editing. To understand the molecular basis for DNA adenosine deamination by adenine base editors (ABEs), we determined a 3.2-angstrom resolution cryo-electron microscopy structure of ABE8e in a substrate-bound state in which the deaminase domain engages DNA exposed within the CRISPR-Cas9 R-loop complex. Kinetic and structural data suggest that ABE8e catalyzes DNA deamination up to ~1100-fold faster than earlier ABEs because of mutations that stabilize DNA substrates in a constrained, transfer RNA-like conformation. Furthermore, ABE8e's accelerated DNA deamination suggests a previously unobserved transient DNA melting that may occur during double-stranded DNA surveillance by CRISPR-Cas9. These results explain ABE8e-mediated base-editing outcomes and inform the future design of base editors.
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Affiliation(s)
- Audrone Lapinaite
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Gavin J Knott
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.,Monash Biomedicine Discovery Institute, Department of Biochemistry & Molecular Biology, Monash University, Victoria 3800, Australia
| | - Cody M Palumbo
- Department of Chemistry, University of California, Davis, CA 95616, USA
| | - Enrique Lin-Shiao
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Michelle F Richter
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA 02141, USA.,Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.,Howard Hughes Medical Institute, Harvard University, Cambridge, MA 02138, USA
| | - Kevin T Zhao
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA 02141, USA.,Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.,Howard Hughes Medical Institute, Harvard University, Cambridge, MA 02138, USA
| | - Peter A Beal
- Department of Chemistry, University of California, Davis, CA 95616, USA
| | - David R Liu
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA 02141, USA.,Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.,Howard Hughes Medical Institute, Harvard University, Cambridge, MA 02138, USA
| | - Jennifer A Doudna
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA. .,Innovative Genomics Institute, University of California, Berkeley, CA 94720, USA.,MBIB Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.,Department of Chemistry, University of California, Berkeley, CA 94720, USA.,Howard Hughes Medical Institute, University of California, Berkeley, CA 94720, USA.,Gladstone Institute of Data Science and Biotechnology, Gladstone Institutes, San Francisco, CA 94158, USA
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19
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Kong XY, Vik ES, Nawaz MS, Berges N, Dahl TB, Vågbø C, Suganthan R, Segers F, Holm S, Quiles-Jiménez A, Gregersen I, Fladeby C, Aukrust P, Bjørås M, Klungland A, Halvorsen B, Alseth I. Deletion of Endonuclease V suppresses chemically induced hepatocellular carcinoma. Nucleic Acids Res 2020; 48:4463-4479. [PMID: 32083667 PMCID: PMC7192598 DOI: 10.1093/nar/gkaa115] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 02/08/2020] [Accepted: 02/13/2020] [Indexed: 12/13/2022] Open
Abstract
Endonuclease V (EndoV) is a conserved inosine-specific ribonuclease with unknown biological function. Here, we present the first mouse model lacking EndoV, which is viable without visible abnormalities. We show that endogenous murine EndoV cleaves inosine-containing RNA in vitro, nevertheless a series of experiments fails to link an in vivo function to processing of such transcripts. As inosine levels and adenosine-to-inosine editing often are dysregulated in hepatocellular carcinoma (HCC), we chemically induced HCC in mice. All mice developed liver cancer, however, EndoV−/− tumors were significantly fewer and smaller than wild type tumors. Opposed to human HCC, adenosine deaminase mRNA expression and site-specific editing were unaltered in our model. Loss of EndoV did not affect editing levels in liver tumors, however mRNA expression of a selection of cancer related genes were reduced. Inosines are also found in certain tRNAs and tRNAs are cleaved during stress to produce signaling entities. tRNA fragmentation was dysregulated in EndoV−/− livers and apparently, inosine-independent. We speculate that the inosine-ribonuclease activity of EndoV is disabled in vivo, but RNA binding allowed to promote stabilization of transcripts or recruitment of proteins to fine-tune gene expression. The EndoV−/− tumor suppressive phenotype calls for related studies in human HCC.
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Affiliation(s)
- Xiang Yi Kong
- Research Institute of Internal Medicine, Oslo University Hospital HF, Rikshospitalet, NO-0424 Oslo, Norway
| | - Erik Sebastian Vik
- Department of Microbiology, Oslo University Hospital HF, Rikshospitalet and University of Oslo, NO-0424 Oslo, Norway
| | - Meh Sameen Nawaz
- Department of Microbiology, Oslo University Hospital HF, Rikshospitalet and University of Oslo, NO-0424 Oslo, Norway
| | - Natalia Berges
- Department of Microbiology, Oslo University Hospital HF, Rikshospitalet and University of Oslo, NO-0424 Oslo, Norway
| | - Tuva Børresdatter Dahl
- Research Institute of Internal Medicine, Oslo University Hospital HF, Rikshospitalet, NO-0424 Oslo, Norway.,Department of Microbiology, Oslo University Hospital HF, Rikshospitalet and University of Oslo, NO-0424 Oslo, Norway
| | - Cathrine Vågbø
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Rajikala Suganthan
- Department of Microbiology, Oslo University Hospital HF, Rikshospitalet and University of Oslo, NO-0424 Oslo, Norway
| | - Filip Segers
- Research Institute of Internal Medicine, Oslo University Hospital HF, Rikshospitalet, NO-0424 Oslo, Norway
| | - Sverre Holm
- Research Institute of Internal Medicine, Oslo University Hospital HF, Rikshospitalet, NO-0424 Oslo, Norway
| | - Ana Quiles-Jiménez
- Research Institute of Internal Medicine, Oslo University Hospital HF, Rikshospitalet, NO-0424 Oslo, Norway.,Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, NO-0317 Oslo, Norway
| | - Ida Gregersen
- Research Institute of Internal Medicine, Oslo University Hospital HF, Rikshospitalet, NO-0424 Oslo, Norway
| | - Cathrine Fladeby
- Department of Microbiology, Oslo University Hospital HF, Rikshospitalet and University of Oslo, NO-0424 Oslo, Norway
| | - Pål Aukrust
- Research Institute of Internal Medicine, Oslo University Hospital HF, Rikshospitalet, NO-0424 Oslo, Norway.,Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, NO-0317 Oslo, Norway.,Section of Clinical Immunology and Infectious Diseases, Oslo University Hospital, Rikshospitalet, NO-0424 Oslo, Norway
| | - Magnar Bjørås
- Department of Microbiology, Oslo University Hospital HF, Rikshospitalet and University of Oslo, NO-0424 Oslo, Norway.,Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Arne Klungland
- Department of Microbiology, Oslo University Hospital HF, Rikshospitalet and University of Oslo, NO-0424 Oslo, Norway.,Department of Molecular Medicine, Institute of Basic Medical Sciences, University ofOslo, NO-0317 Oslo, Norway
| | - Bente Halvorsen
- Research Institute of Internal Medicine, Oslo University Hospital HF, Rikshospitalet, NO-0424 Oslo, Norway.,Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, NO-0317 Oslo, Norway
| | - Ingrun Alseth
- Department of Microbiology, Oslo University Hospital HF, Rikshospitalet and University of Oslo, NO-0424 Oslo, Norway
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20
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Richter MF, Zhao KT, Eton E, Lapinaite A, Newby GA, Thuronyi BW, Wilson C, Koblan LW, Zeng J, Bauer DE, Doudna JA, Liu DR. Phage-assisted evolution of an adenine base editor with improved Cas domain compatibility and activity. Nat Biotechnol 2020; 38:883-891. [PMID: 32433547 PMCID: PMC7357821 DOI: 10.1038/s41587-020-0453-z] [Citation(s) in RCA: 473] [Impact Index Per Article: 118.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 02/02/2020] [Accepted: 02/07/2020] [Indexed: 12/19/2022]
Abstract
Applications of adenine base editors (ABEs) have been constrained by the limited compatibility of the deoxyadenosine deaminase component with Cas homologs other than SpCas9. We evolved the deaminase component of ABE7.10 using phage-assisted non-continuous and continuous evolution (PANCE and PACE), which resulted in ABE8e. ABE8e contains eight additional mutations that increase activity (kapp) 590-fold compared with that of ABE7.10. ABE8e offers substantially improved editing efficiencies when paired with a variety of Cas9 or Cas12 homologs. ABE8e is more processive than ABE7.10, which could benefit screening, disruption of regulatory regions and multiplex base editing applications. A modest increase in Cas9-dependent and -independent DNA off-target editing, and in transcriptome-wide RNA off-target editing can be ameliorated by the introduction of an additional mutation in the TadA-8e domain. Finally, we show that ABE8e can efficiently install natural mutations that upregulate fetal hemoglobin expression in the BCL11A enhancer or in the the HBG promoter in human cells, targets that were poorly edited with ABE7.10. ABE8e augments the effectiveness and applicability of adenine base editing.
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Affiliation(s)
- Michelle F Richter
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, USA
| | - Kevin T Zhao
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, USA
| | - Elliot Eton
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, USA
| | - Audrone Lapinaite
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
- School of Molecular Sciences, Arizona State University, Tempe, AZ, USA
| | - Gregory A Newby
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, USA
| | - B W Thuronyi
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, USA
- Department of Chemistry, Williams College, Williamstown, MA, USA
| | - Christopher Wilson
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, USA
| | - Luke W Koblan
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, USA
| | - Jing Zeng
- Division of Hematology/Oncology, Boston Children's Hospital, Boston, MA, USA
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA, USA
- Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
| | - Daniel E Bauer
- Division of Hematology/Oncology, Boston Children's Hospital, Boston, MA, USA
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA, USA
- Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
| | - Jennifer A Doudna
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Howard Hughes Medical Institute, University of California, Berkeley, CA, USA
- Innovative Genomics Institute, University of California, Berkeley, CA, USA
- Department of Chemistry, University of California, Berkeley, CA, USA
| | - David R Liu
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, USA.
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA.
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, USA.
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21
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Knutson SD, Arthur RA, Johnston HR, Heemstra JM. Selective Enrichment of A-to-I Edited Transcripts from Cellular RNA Using Endonuclease V. J Am Chem Soc 2020; 142:5241-5251. [PMID: 32109061 DOI: 10.1021/jacs.9b13406] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Creating accurate maps of A-to-I RNA editing activity is vital to improving our understanding of the biological role of this process and harnessing it as a signal for disease diagnosis. Current RNA sequencing techniques are susceptible to random sampling limitations due to the complexity of the transcriptome and require large amounts of RNA material, specialized instrumentation, and high read counts to accurately interrogate A-to-I editing sites. To address these challenges, we show that Escherichia coli Endonuclease V (eEndoV), an inosine-cleaving enzyme, can be repurposed to bind and isolate A-to-I edited transcripts from cellular RNA. While Mg2+ enables eEndoV to catalyze RNA cleavage, we show that similar levels of Ca2+ instead promote binding of inosine without cleavage and thus enable high affinity capture of inosine in RNA. We leverage this capability to demonstrate EndoVIPER-seq (Endonuclease V inosine precipitation enrichment sequencing) as a facile and effective method to enrich A-to-I edited transcripts prior to RNA-seq, producing significant increases in the coverage and detection of identified editing sites. We envision the use of this approach as a straightforward and cost-effective strategy to improve the epitranscriptomic informational density of RNA samples, facilitating a deeper understanding of the functional roles of A-to-I editing.
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Affiliation(s)
- Steve D Knutson
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - Robert A Arthur
- Emory Integrated Computational Core, Emory Integrated Core Facilities, Emory University, Atlanta, Georgia 30322, United States
| | - H Richard Johnston
- Department of Human Genetics, Emory University, Atlanta, Georgia 30322, United States
| | - Jennifer M Heemstra
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
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22
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Berges N, Nawaz MS, Børresdatter Dahl T, Hagen L, Bjørås M, Laerdahl JK, Alseth I. Complex alternative splicing of human Endonuclease V mRNA, but evidence for only a single protein isoform. PLoS One 2019; 14:e0225081. [PMID: 31703097 PMCID: PMC6839837 DOI: 10.1371/journal.pone.0225081] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 10/27/2019] [Indexed: 12/22/2022] Open
Abstract
Endonuclease V (ENDOV) is a ribonuclease with affinity for inosine which is the deamination product of adenosine. The genomes of most organisms, including human, encode ENDOV homologs, yet knowledge about in vivo functions and gene regulation is sparse. To contribute in this field, we analyzed mRNA and protein expression of human ENDOV (hENDOV). Analyses of public sequence databases revealed numerous hENDOV transcript variants suggesting extensive alternative splicing. Many of the transcripts lacked one or more exons corresponding to conserved regions of the ENDOV core domain, suggesting that these transcripts do not encode for active proteins. Three complete transcripts were found with open reading frames encoding 282, 308 and 309 amino acids, respectively. Recombinant hENDOV 308 and hENDOV 309 share the same cleavage activity as hENDOV 282 which is the variant that has been used in previous studies of hENDOV. However, hENDOV 309 binds inosine-containing RNA with stronger affinity than the other isoforms. Overexpressed GFP-fused isoforms were found in cytoplasm, nucleoli and arsenite induced stress granules in human cells as previously reported for hENDOV 282. RT-qPCR analysis of the 3’-termini showed that hENDOV 308 and hENDOV 309 transcripts are more abundant than hENDOV 282 transcripts in immortalized cell lines, but not in primary cells, suggesting that cells regulate hENDOV mRNA expression. In spite of the presence of all three full-length transcripts, mass spectrometry analyses identified peptides corresponding to the hENDOV 309 isoform only. This result suggests that further studies of human ENDOV should rather encompass the hENDOV 309 isoform.
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Affiliation(s)
- Natalia Berges
- Department of Microbiology, Oslo University Hospital Rikshospitalet and University of Oslo, Oslo, Norway
| | - Meh Sameen Nawaz
- Department of Microbiology, Oslo University Hospital Rikshospitalet and University of Oslo, Oslo, Norway
| | - Tuva Børresdatter Dahl
- Department of Microbiology, Oslo University Hospital Rikshospitalet and University of Oslo, Oslo, Norway
- Research Institute of Internal Medicine, Oslo University Hospital Rikshospitalet and Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Lars Hagen
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
- PROMEC Core Facility for Proteomics and Modomics, Norwegian University of Science and Technology and Central Norway Regional Health Authority, Trondheim, Norway
| | - Magnar Bjørås
- Department of Microbiology, Oslo University Hospital Rikshospitalet and University of Oslo, Oslo, Norway
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - Jon K. Laerdahl
- Department of Microbiology, Oslo University Hospital Rikshospitalet and University of Oslo, Oslo, Norway
| | - Ingrun Alseth
- Department of Microbiology, Oslo University Hospital Rikshospitalet and University of Oslo, Oslo, Norway
- * E-mail:
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Evolution of Inosine-Specific Endonuclease V from Bacterial DNase to Eukaryotic RNase. Mol Cell 2019; 76:44-56.e3. [PMID: 31444105 DOI: 10.1016/j.molcel.2019.06.046] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 05/16/2019] [Accepted: 06/27/2019] [Indexed: 02/01/2023]
Abstract
Endonuclease V (EndoV) cleaves the second phosphodiester bond 3' to a deaminated adenosine (inosine). Although highly conserved, EndoV homologs change substrate preference from DNA in bacteria to RNA in eukaryotes. We have characterized EndoV from six different species and determined crystal structures of human EndoV and three EndoV homologs from bacteria to mouse in complex with inosine-containing DNA/RNA hybrid or double-stranded RNA (dsRNA). Inosine recognition is conserved, but changes in several connecting loops in eukaryotic EndoV confer recognition of 3 ribonucleotides upstream and 7 or 8 bp of dsRNA downstream of the cleavage site, and bacterial EndoV binds only 2 or 3 nt flanking the scissile phosphate. In addition to the two canonical metal ions in the active site, a third Mn2+ that coordinates the nucleophilic water appears necessary for product formation. Comparison of EndoV with its homologs RNase H1 and Argonaute reveals the principles by which these enzymes recognize RNA versus DNA.
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24
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Rao TVP, Kuzminov A. Sources of thymidine and analogs fueling futile damage-repair cycles and ss-gap accumulation during thymine starvation in Escherichia coli. DNA Repair (Amst) 2019; 75:1-17. [PMID: 30684682 PMCID: PMC6382538 DOI: 10.1016/j.dnarep.2019.01.002] [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: 09/08/2018] [Revised: 12/31/2018] [Accepted: 01/06/2019] [Indexed: 10/27/2022]
Abstract
Thymine deprivation in thyA mutant E. coli causes thymineless death (TLD) and is the mode of action of popular antibacterial and anticancer drugs, yet the mechanisms of TLD are still unclear. TLD comprises three defined phases: resistance, rapid exponential death (RED) and survival, with the nature of the resistance phase and of the transition to the RED phase holding key to TLD pathology. We propose that a limited source of endogenous thymine maintains replication forks through the resistance phase. When this source ends, forks undergo futile break-repair cycle during the RED phase, eventually rendering the chromosome non-functional. Two obvious sources of the endogenous thymine are degradation of broken chromosomal DNA and recruitment of thymine from stable RNA. However, mutants that cannot degrade broken chromosomal DNA or lack ribo-thymine, instead of shortening the resistance phase, deepen the RED phase, meaning that only a small fraction of T-starved cells tap into these sources. Interestingly, the substantial chromosomal DNA accumulation during the resistance phase is negated during the RED phase, suggesting futile cycle of incorporation and excision of wrong nucleotides. We tested incorporation of dU or rU, finding some evidence for both, but DNA-dU incorporation accelerates TLD only when intracellular [dUTP] is increased by the dut mutation. In the dut ung mutant, with increased DNA-dU incorporation and no DNA-dU excision, replication is in fact rescued even without dT, but TLD still occurs, suggesting different mechanisms. Finally, we found that continuous DNA synthesis during thymine starvation makes chromosomal DNA increasingly single-stranded, and even the dut ung defect does not completely block this ss-gap accumulation. We propose that instability of single-strand gaps underlies the pathology of thymine starvation.
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Affiliation(s)
- T V Pritha Rao
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Andrei Kuzminov
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
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25
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YwqL (EndoV), ExoA and PolA act in a novel alternative excision pathway to repair deaminated DNA bases in Bacillus subtilis. PLoS One 2019; 14:e0211653. [PMID: 30726292 PMCID: PMC6364969 DOI: 10.1371/journal.pone.0211653] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 01/17/2019] [Indexed: 11/19/2022] Open
Abstract
DNA deamination generates base transitions and apurinic/apyrimidinic (AP)-sites which are potentially genotoxic and cytotoxic. In Bacillus subtilis uracil can be removed from DNA by the uracil DNA-glycosylase through the base excision repair pathway. Genetic evidence suggests that B. subtilis YwqL, a homolog of Endonuclease-V (EndoV), acts on a wider spectrum of deaminated bases but the factors that complete this pathway have remained elusive. Here, we report that a purified His6-YwqL (hereafter BsEndoV) protein had in vitro endonuclease activity against double-stranded DNAs containing a single uracil (U), hypoxanthine (Hx), xanthine (X) or an AP site. Interestingly, while BsEndoV catalyzed a single strand break at the second phosphodiester bond towards the 3'-end of the U and AP lesions, there was an additional cleavage of the phosphodiester bond preceding the Hx and X lesions. Remarkably, the repair event initiated by BsEndoV on Hx and X, was completed by a recombinant B. subtilis His6-DNA polymerase A (BsPolA), but not on BsEndoV-processed U and AP lesions. For the latter lesions a second excision event performed by a recombinant B. subtilis His6-ExoA (BsExoA) was necessary before completion of their repair by BsPolA. These results suggest the existence of a novel alternative excision repair pathway in B. subtilis that counteracts the genotoxic effects of base deamination. The presence of this novel pathway in vivo in B. subtilis was also supported by analysis of effects of single or multiple deletions of exoA, endoV and polA on spontaneous mutations in growing cells, and the sensitivity of growing wild-type and mutant cells to a DNA deaminating agent.
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26
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Breaking the speed limit with multimode fast scanning of DNA by Endonuclease V. Nat Commun 2018; 9:5381. [PMID: 30568191 PMCID: PMC6300609 DOI: 10.1038/s41467-018-07797-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 11/27/2018] [Indexed: 01/04/2023] Open
Abstract
In order to preserve genomic stability, cells rely on various repair pathways for removing DNA damage. The mechanisms how enzymes scan DNA and recognize their target sites are incompletely understood. Here, by using high-localization precision microscopy along with 133 Hz high sampling rate, we have recorded EndoV and OGG1 interacting with 12-kbp elongated λ-DNA in an optical trap. EndoV switches between three distinct scanning modes, each with a clear range of activation energy barriers. These results concur with average diffusion rate and occupancy of states determined by a hidden Markov model, allowing us to infer that EndoV confinement occurs when the intercalating wedge motif is involved in rigorous probing of the DNA, while highly mobile EndoV may disengage from a strictly 1D helical diffusion mode and hop along the DNA. This makes EndoV the first example of a monomeric, single-conformation and single-binding-site protein demonstrating the ability to switch between three scanning modes. How DNA repair proteins locate their target sites on DNA is still a matter of debate. Here the authors characterize by single-molecule fluorescence imaging the modes of scanning adopted by bacterial endonuclease V as it moves along linear DNA tracks.
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27
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Zuin Fantoni N, Molphy Z, Slator C, Menounou G, Toniolo G, Mitrikas G, McKee V, Chatgilialoglu C, Kellett A. Polypyridyl‐Based Copper Phenanthrene Complexes: A New Type of Stabilized Artificial Chemical Nuclease. Chemistry 2018; 25:221-237. [DOI: 10.1002/chem.201804084] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Indexed: 11/09/2022]
Affiliation(s)
- Nicoló Zuin Fantoni
- School of Chemical Sciences and National Institute for Cellular, BiotechnologyDublin City University 9 Glasnevin, Dublin Ireland
| | - Zara Molphy
- School of Chemical Sciences and National Institute for Cellular, BiotechnologyDublin City University 9 Glasnevin, Dublin Ireland
| | - Creina Slator
- School of Chemical Sciences and National Institute for Cellular, BiotechnologyDublin City University 9 Glasnevin, Dublin Ireland
| | - Georgia Menounou
- ISOF-CNR Area della Ricerca di Bologna Via P. Gobetti 101 40129 Bologna Italy
| | - Gianluca Toniolo
- Institute of Nanoscience and Nanotechnology, N.C.S.R. Demokritos Agia Paraskevi Attikis P.O. Box 60037, 15341 Athens Greece
| | - George Mitrikas
- Institute of Nanoscience and Nanotechnology, N.C.S.R. Demokritos Agia Paraskevi Attikis P.O. Box 60037, 15341 Athens Greece
| | - Vickie McKee
- School of Chemical Sciences and National Institute for Cellular, BiotechnologyDublin City University 9 Glasnevin, Dublin Ireland
- Department of Physics, Chemistry and PharmacyUniversity of Southern Denmark Campusvej 55 5230 Odense M Denmark
| | - Chryssostomos Chatgilialoglu
- ISOF-CNR Area della Ricerca di Bologna Via P. Gobetti 101 40129 Bologna Italy
- Institute of Nanoscience and Nanotechnology, N.C.S.R. Demokritos Agia Paraskevi Attikis P.O. Box 60037, 15341 Athens Greece
| | - Andrew Kellett
- School of Chemical Sciences and National Institute for Cellular, BiotechnologyDublin City University 9 Glasnevin, Dublin Ireland
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28
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Wang Y, Zhang L, Zhu X, Li Y, Shi H, Oger P, Yang Z. Biochemical characterization of a thermostable endonuclease V from the hyperthermophilic euryarchaeon Thermococcus barophilus Ch5. Int J Biol Macromol 2018; 117:17-24. [DOI: 10.1016/j.ijbiomac.2018.05.155] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 05/20/2018] [Accepted: 05/22/2018] [Indexed: 01/13/2023]
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29
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Gruber CC, Walker GC. Incomplete base excision repair contributes to cell death from antibiotics and other stresses. DNA Repair (Amst) 2018; 71:108-117. [PMID: 30181041 DOI: 10.1016/j.dnarep.2018.08.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Numerous lethal stresses in bacteria including antibiotics, thymineless death, and MalE-LacZ expression trigger an increase in the production of reactive oxygen species. This results in the oxidation of the nucleotide pool by radicals produced by Fenton chemistry. Following the incorporation of these oxidized nucleotides into the genome, the cell's unsuccessful attempt to repair these lesions through base excision repair (BER) contributes causally to the lethality of these stresses. We review the evidence for this phenomenon of incomplete BER-mediated cell death and discuss how better understanding this pathway could contribute to the development of new antibiotics.
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Affiliation(s)
- Charley C Gruber
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, 02139, United States
| | - Graham C Walker
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, 02139, United States.
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30
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Su KY, Lin LI, Goodman SD, Yen RS, Wu CY, Chang WC, Yang YC, Cheng WC, Fang WH. DNA polymerase I proofreading exonuclease activity is required for endonuclease V repair pathway both in vitro and in vivo. DNA Repair (Amst) 2018. [DOI: 10.1016/j.dnarep.2018.02.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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31
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Application of single nucleotide extension and MALDI-TOF mass spectrometry in proofreading and DNA repair assay. DNA Repair (Amst) 2017; 61:63-75. [PMID: 29223016 DOI: 10.1016/j.dnarep.2017.11.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 10/07/2017] [Accepted: 11/30/2017] [Indexed: 01/20/2023]
Abstract
Proofreading and DNA repair are important factors in maintaining the high fidelity of genetic information during DNA replication. Herein, we designed a non-labeled and non-radio-isotopic simple method to measure proofreading. An oligonucleotide primer is annealed to a template DNA forming a mismatched site and is proofread by Klenow fragment of Escherichia coli DNA polymerase I (pol I) in the presence of all four dideoxyribonucleotide triphosphates. The proofreading excision products and re-synthesis products of single nucleotide extension are subjected to MALDI-TOF mass spectrometry (MS). The proofreading at the mismatched site is identified by the mass change of the primer. We examined proofreading of Klenow fragment with DNAs containing various base mismatches. Single mismatches at the primer terminus can be proofread efficiently. Internal single mismatches can also be proofread at different efficiencies, with the best correction for mismatches located 2-4-nucleotides from the primer terminus. For mismatches located 5-nucleotides from the primer terminus there was partial correction and extension. No significant proofreading was observed for mismatches located 6-9-nucleotides from the primer terminus. We also subjected primers containing 3' penultimate deoxyinosine (dI) lesions, which mimic endonuclease V nicked repair intermediates, to pol I repair assay. The results showed that T-I was a better substrate than G-I and A-I, however C-I was refractory to repair. The high resolution of MS results clearly demonstrated that all the penultimate T-I, G-I and A-I substrates had been excised last 2 dI-containing nucleotides by pol I before adding a correct ddNMP, however, pol I proofreading exonuclease tolerated the penultimate C-I mismatch allowing the primer to be extended by polymerase activity.
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32
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Insights into the role of endonuclease V in RNA metabolism in Trypanosoma brucei. Sci Rep 2017; 7:8505. [PMID: 28819113 PMCID: PMC5561087 DOI: 10.1038/s41598-017-08910-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Accepted: 07/14/2017] [Indexed: 01/05/2023] Open
Abstract
Inosine may arise in DNA as a result of oxidative deamination of adenine or misincorporation of deoxyinosine triphosphate during replication. On the other hand, the occurrence of inosine in RNA is considered a normal and essential modification induced by specific adenosine deaminases acting on mRNA and tRNA. In prokaryotes, endonuclease V (EndoV) can recognize and cleave inosine-containing DNA. In contrast, mammalian EndoVs preferentially cleave inosine-containing RNA, suggesting a role in RNA metabolism for the eukaryotic members of this protein family. We have performed a biochemical characterization of EndoV from the protozoan parasite Trypanosoma brucei. In vitro, TbEndoV efficiently processes single-stranded RNA oligonucleotides with inosine, including A to I-edited tRNA-like substrates but exhibits weak activity over DNA, except when a ribonucleotide is placed 3' to the inosine. Immunolocalization studies performed in procyclic forms indicate that TbEndoV is mainly cytosolic yet upon nutritional stress it redistributes and accumulates in stress granules colocalizing with the DEAD-box helicase TbDhh1. RNAi-mediated depletion of TbEndoV results in moderate growth defects in procyclic cells while the two EndoV alleles could be readily knocked out in bloodstream forms. Taken together, these observations suggest an important role of TbEndoV in RNA metabolism in procyclic forms of the parasite.
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Aag Hypoxanthine-DNA Glycosylase Is Synthesized in the Forespore Compartment and Involved in Counteracting the Genotoxic and Mutagenic Effects of Hypoxanthine and Alkylated Bases in DNA during Bacillus subtilis Sporulation. J Bacteriol 2016; 198:3345-3354. [PMID: 27698084 DOI: 10.1128/jb.00625-16] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 09/28/2016] [Indexed: 12/11/2022] Open
Abstract
Aag from Bacillus subtilis has been implicated in in vitro removal of hypoxanthine and alkylated bases from DNA. The regulation of expression of aag in B. subtilis and the resistance to genotoxic agents and mutagenic properties of an Aag-deficient strain were studied here. A strain with a transcriptional aag-lacZ fusion expressed low levels of β-galactosidase during growth and early sporulation but exhibited increased transcription during late stages of this developmental process. Notably, aag-lacZ expression was higher inside the forespore than in the mother cell compartment, and this expression was abolished in a sigG-deficient background, suggesting a forespore-specific mechanism of aag transcription. Two additional findings supported this suggestion: (i) expression of an aag-yfp fusion was observed in the forespore, and (ii) in vivo mapping of the aag transcription start site revealed the existence of upstream regulatory sequences possessing homology to σG-dependent promoters. In comparison with the wild-type strain, disruption of aag significantly reduced survival of sporulating B. subtilis cells following nitrous acid or methyl methanesulfonate treatments, and the Rifr mutation frequency was significantly increased in an aag strain. These results suggest that Aag protects the genome of developing B. subtilis sporangia from the cytotoxic and genotoxic effects of base deamination and alkylation. IMPORTANCE In this study, evidence is presented revealing that aag, encoding a DNA glycosylase implicated in processing of hypoxanthine and alkylated DNA bases, exhibits a forespore-specific pattern of gene expression during B. subtilis sporulation. Consistent with this spatiotemporal mode of expression, Aag was found to protect the sporulating cells of this microorganism from the noxious and mutagenic effects of base deamination and alkylation.
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34
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Kim JI, Tohashi K, Iwai S, Kuraoka I. Inosine-specific ribonuclease activity of natural variants of human endonuclease V. FEBS Lett 2016; 590:4354-4360. [PMID: 27800608 DOI: 10.1002/1873-3468.12470] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 10/13/2016] [Accepted: 10/17/2016] [Indexed: 12/26/2022]
Abstract
Adenine bases in DNA, RNA, and nucleotides are deaminated during normal metabolism via hydrolytic and nitrosative reactions. In RNA, the deaminated product inosine is resolved by human endonuclease V, and mice deficient in this enzyme are cancer-prone. We have now produced, purified, and characterized naturally occurring variants of human endonuclease V (V29I, R112Q, K114R, H141Y, and D201N). We found that H141Y, but not other variants, is catalytically impaired, suggesting that individuals homozygous for H141Y may be predisposed to disease.
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Affiliation(s)
- Jung In Kim
- Division of Chemistry, Graduate School of Engineering Science, Osaka University, Osaka, Japan
| | - Kosuke Tohashi
- Division of Chemistry, Graduate School of Engineering Science, Osaka University, Osaka, Japan
| | - Shigenori Iwai
- Division of Chemistry, Graduate School of Engineering Science, Osaka University, Osaka, Japan
| | - Isao Kuraoka
- Division of Chemistry, Graduate School of Engineering Science, Osaka University, Osaka, Japan
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35
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Nie H, Huang H, Li W, Yang T. A Label-free Time-resolved Luminescent Platform for Sensitive Endonuclease V Detection Based on Exonuclease III Regulated DNA-Tb 3+ Luminescence. ANAL SCI 2016; 32:1245-1250. [PMID: 27829633 DOI: 10.2116/analsci.32.1245] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Endonuclease V (EndoV) plays the important role of nucleotide excision repair (NER) in the maintenance of genomic stability. Highly sensitive detection of EndoV was achieved through an oligonucleotides sensitizing Tb3+ luminescent technique. We found that although both guanine-rich (G-rich) single-stranded DNA and dGMP could enhance the time-resolved luminescence of Tb3+, their efficiencies of enhancement were considerably different. Employing such interesting phenomenon, a label-free and time-resolved luminescent strategy for the sensitive detection of EndoV activity was developed based on DNA-enhanced time-resolved luminescence (TRL) of Tb3+. The EndoV was used to cut off the deoxyinosine site (dI) and convert the 3'-protruding termini to a recessed end, and Exonuclease III (Exo III) was used to enhance the signal contrast via digestion of G-rich DNA to dNTP. Combining with the natural advantages of the TRL, the proposed method exhibited a good linear response to EndoV ranging from 0.005 to 0.4 U/mL, with a low limit of detection of 0.005 U/mL.
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Affiliation(s)
- Huaijun Nie
- State Environmental Protection Key Laboratory of Drinking Water Source Management and Technology, Shenzhen Key Laboratory of Drinking Water Source Safety Control, Shenzhen Research Academy of Environmental Sciences
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36
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Yoneshima Y, Abolhassani N, Iyama T, Sakumi K, Shiomi N, Mori M, Shiomi T, Noda T, Tsuchimoto D, Nakabeppu Y. Deoxyinosine triphosphate induces MLH1/PMS2- and p53-dependent cell growth arrest and DNA instability in mammalian cells. Sci Rep 2016; 6:32849. [PMID: 27618981 PMCID: PMC5020429 DOI: 10.1038/srep32849] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 08/16/2016] [Indexed: 12/30/2022] Open
Abstract
Deoxyinosine (dI) occurs in DNA either by oxidative deamination of a previously incorporated deoxyadenosine residue or by misincorporation of deoxyinosine triphosphate (dITP) from the nucleotide pool during replication. To exclude dITP from the pool, mammals possess specific hydrolysing enzymes, such as inosine triphosphatase (ITPA). Previous studies have shown that deficiency in ITPA results in cell growth suppression and DNA instability. To explore the mechanisms of these phenotypes, we analysed ITPA-deficient human and mouse cells. We found that both growth suppression and accumulation of single-strand breaks in nuclear DNA of ITPA-deficient cells depended on MLH1/PMS2. The cell growth suppression of ITPA-deficient cells also depended on p53, but not on MPG, ENDOV or MSH2. ITPA deficiency significantly increased the levels of p53 protein and p21 mRNA/protein, a well-known target of p53, in an MLH1-dependent manner. Furthermore, MLH1 may also contribute to cell growth arrest by increasing the basal level of p53 activity.
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Affiliation(s)
- Yasuto Yoneshima
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8581, Japan
- Research Institute for Diseases of the Chest, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8581, Japan
| | - Nona Abolhassani
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8581, Japan
| | - Teruaki Iyama
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8581, Japan
| | - Kunihiko Sakumi
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8581, Japan
- Research Center for Nucleotide Pool, Kyushu University, Fukuoka 812-8581, Japan
| | - Naoko Shiomi
- National Institute of Radiological Sciences, Chiba 263-8555, Japan
| | - Masahiko Mori
- National Institute of Radiological Sciences, Chiba 263-8555, Japan
| | - Tadahiro Shiomi
- National Institute of Radiological Sciences, Chiba 263-8555, Japan
| | - Tetsuo Noda
- Cancer Institute, Japanese Foundation for Cancer Research, Tokyo 135-8550, Japan
| | - Daisuke Tsuchimoto
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8581, Japan
- Research Center for Nucleotide Pool, Kyushu University, Fukuoka 812-8581, Japan
| | - Yusaku Nakabeppu
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8581, Japan
- Research Center for Nucleotide Pool, Kyushu University, Fukuoka 812-8581, Japan
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37
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Nawaz MS, Vik ES, Berges N, Fladeby C, Bjørås M, Dalhus B, Alseth I. Regulation of Human Endonuclease V Activity and Relocalization to Cytoplasmic Stress Granules. J Biol Chem 2016; 291:21786-21801. [PMID: 27573237 DOI: 10.1074/jbc.m116.730911] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 08/29/2016] [Indexed: 01/01/2023] Open
Abstract
Endonuclease V (EndoV) is an enzyme with specificity for inosines in nucleic acids. Whereas the bacterial homologs are active on both DNA and RNA, the mammalian variants only cleave RNA, at least when assayed with recombinant proteins. Here we show that ectopically expressed, as well as endogenously expressed human (h)EndoV, share the same enzymatic properties as the recombinant protein and cleaves RNA with inosine but not DNA. In search for proteins interacting with hEndoV, polyadenylate-binding protein C1 (PABPC1) was identified. The association between PABPC1 and hEndoV is RNA dependent and furthermore, PABPC1 stimulates hEndoV activity and affinity for inosine-containing RNA. Upon cellular stress, PABPC1 relocates to cytoplasmic stress granules that are multimolecular aggregates of stalled translation initiation complexes formed to aid cell recovery. Arsenite, as well as other agents, triggered relocalization also of hEndoV to cytoplasmic stress granules. As inosines in RNA are highly abundant, hEndoV activity is likely regulated in cells to avoid aberrant cleavage of inosine-containing transcripts. Indeed, we find that hEndoV cleavage is inhibited by normal intracellular ATP concentrations. The ATP stores inside a cell do not overlay stress granules and we suggest that hEndoV is redistributed to stress granules as a strategy to create a local environment low in ATP to permit hEndoV activity.
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Affiliation(s)
- Meh Sameen Nawaz
- From the Department of Microbiology, Oslo University Hospital HF, Rikshospitalet, and University of Oslo, NO-0424 Oslo
| | - Erik Sebastian Vik
- From the Department of Microbiology, Oslo University Hospital HF, Rikshospitalet, and University of Oslo, NO-0424 Oslo
| | - Natalia Berges
- From the Department of Microbiology, Oslo University Hospital HF, Rikshospitalet, and University of Oslo, NO-0424 Oslo
| | - Cathrine Fladeby
- From the Department of Microbiology, Oslo University Hospital HF, Rikshospitalet, and University of Oslo, NO-0424 Oslo
| | - Magnar Bjørås
- From the Department of Microbiology, Oslo University Hospital HF, Rikshospitalet, and University of Oslo, NO-0424 Oslo.,the Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, NO-7491 Trondheim, and
| | - Bjørn Dalhus
- From the Department of Microbiology, Oslo University Hospital HF, Rikshospitalet, and University of Oslo, NO-0424 Oslo.,the Department of Medical Biochemistry, Institute for Clinical Medicine, University of Oslo, NO-0424 Oslo, Norway
| | - Ingrun Alseth
- From the Department of Microbiology, Oslo University Hospital HF, Rikshospitalet, and University of Oslo, NO-0424 Oslo,
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38
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Crystal structure and MD simulation of mouse EndoV reveal wedge motif plasticity in this inosine-specific endonuclease. Sci Rep 2016; 6:24979. [PMID: 27108838 PMCID: PMC4842958 DOI: 10.1038/srep24979] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Accepted: 04/07/2016] [Indexed: 01/06/2023] Open
Abstract
Endonuclease V (EndoV) is an enzyme with specificity for deaminated adenosine (inosine) in nucleic acids. EndoV from Escherichia coli (EcEndoV) acts both on inosines in DNA and RNA, whereas the human homolog cleaves only at inosines in RNA. Inosines in DNA are mutagenic and the role of EndoV in DNA repair is well established. In contrast, the biological function of EndoV in RNA processing is largely unexplored. Here we have characterized a second mammalian EndoV homolog, mouse EndoV (mEndoV), and show that mEndoV shares the same RNA selectivity as human EndoV (hEndoV). Mouse EndoV cleaves the same inosine-containing substrates as hEndoV, but with reduced efficiencies. The crystal structure of mEndoV reveals a conformation different from the hEndoV and prokaryotic EndoV structures, particularly for the conserved tyrosine in the wedge motif, suggesting that this strand separating element has some flexibility. Molecular dynamics simulations of mouse and human EndoV reveal alternative conformations for the invariant tyrosine. The configuration of the active site, on the other hand, is very similar between the prokaryotic and mammalian versions of EndoV.
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Kuraoka I. Diversity of Endonuclease V: From DNA Repair to RNA Editing. Biomolecules 2015; 5:2194-206. [PMID: 26404388 PMCID: PMC4693234 DOI: 10.3390/biom5042194] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 09/09/2015] [Accepted: 09/11/2015] [Indexed: 11/16/2022] Open
Abstract
Deamination of adenine occurs in DNA, RNA, and their precursors via a hydrolytic reaction and a nitrosative reaction. The generated deaminated products are potentially mutagenic because of their structural similarity to natural bases, which in turn leads to erroneous nucleotide pairing and subsequent disruption of cellular metabolism. Incorporation of deaminated precursors into the nucleic acid strand occurs during nucleotide synthesis by DNA and RNA polymerases or base modification by DNA- and/or RNA-editing enzymes during cellular functions. In such cases, removal of deaminated products from DNA and RNA by a nuclease might be required depending on the cellular function. One such enzyme, endonuclease V, recognizes deoxyinosine and cleaves 3' end of the damaged base in double-stranded DNA through an alternative excision repair mechanism in Escherichia coli, whereas in Homo sapiens, it recognizes and cleaves inosine in single-stranded RNA. However, to explore the role of endonuclease V in vivo, a detailed analysis of cell biology is required. Based on recent reports and developments on endonuclease V, we discuss the potential functions of endonuclease V in DNA repair and RNA metabolism.
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Affiliation(s)
- Isao Kuraoka
- Division of Chemistry, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan.
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Lee CC, Yang YC, Goodman SD, Chen S, Huang TY, Cheng WC, Lin LI, Fang WH. Deoxyinosine repair in nuclear extracts of human cells. Cell Biosci 2015; 5:52. [PMID: 26357532 PMCID: PMC4563847 DOI: 10.1186/s13578-015-0044-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Accepted: 09/02/2015] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Deamination of adenine can occur spontaneously under physiological conditions generating the highly mutagenic lesion, hypoxanthine. This process is enhanced by ROS from exposure of DNA to ionizing radiation, UV light, nitrous acid, or heat. Hypoxanthine in DNA can pair with cytosine which results in A:T to G:C transition mutations after DNA replication. In Escherichia coli, deoxyinosine (hypoxanthine deoxyribonucleotide, dI) is removed through an alternative excision repair pathway initiated by endonuclease V. However, the correction of dI in mammalian cells appears more complex and was not fully understood. RESULTS All four possible dI-containing heteroduplex DNAs, including A-I, C-I, G-I, and T-I were introduced to repair reactions containing extracts from human cells. The repair reaction requires magnesium, dNTPs, and ATP as cofactors. We found G-I was the best substrate followed by T-I, A-I and C-I, respectively. Moreover, judging from the repair requirements and sensitivity to specific polymerase inhibitors, there were overlapping repair activities in processing of dI in DNA. Indeed, a hereditable non-polyposis colorectal cancer cell line (HCT116) demonstrated lower dI repair activity that was partially attributed to lack of mismatch repair. CONCLUSIONS A plasmid-based convenient and non-radioisotopic method was created to study dI repair in human cells. Mutagenic dI lesions processed in vitro can be scored by restriction enzyme cleavage to evaluate the repair. The repair assay described in this study provides a good platform for further investigation of human repair pathways involved in dI processing and their biological significance in mutation prevention.
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Affiliation(s)
- Chia-Chia Lee
- />Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, #7, Chung-Shan South Road, Taipei, 10002 Taiwan ROC
| | - Ya-Chien Yang
- />Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, #7, Chung-Shan South Road, Taipei, 10002 Taiwan ROC
- />Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, 10002 Taiwan ROC
| | - Steven D. Goodman
- />Center for Microbial Pathogenesis, Nationwide Children’s Hospital, Columbus, OH USA
| | - Shi Chen
- />Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, #7, Chung-Shan South Road, Taipei, 10002 Taiwan ROC
| | - Teng-Yung Huang
- />Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, #7, Chung-Shan South Road, Taipei, 10002 Taiwan ROC
| | - Wern-Cherng Cheng
- />Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, 10002 Taiwan ROC
| | - Liang-In Lin
- />Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, #7, Chung-Shan South Road, Taipei, 10002 Taiwan ROC
- />Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, 10002 Taiwan ROC
| | - Woei-horng Fang
- />Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, #7, Chung-Shan South Road, Taipei, 10002 Taiwan ROC
- />Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, 10002 Taiwan ROC
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Evidence for Retromutagenesis as a Mechanism for Adaptive Mutation in Escherichia coli. PLoS Genet 2015; 11:e1005477. [PMID: 26305558 PMCID: PMC4548950 DOI: 10.1371/journal.pgen.1005477] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 07/30/2015] [Indexed: 11/19/2022] Open
Abstract
Adaptive mutation refers to the continuous outgrowth of new mutants from a non-dividing cell population during selection, in apparent violation of the neo-Darwinian principle that mutation precedes selection. One explanation is that of retromutagenesis, in which a DNA lesion causes a transcriptional mutation that yields a mutant protein, allowing escape from selection. This enables a round of DNA replication that establishes heritability. Because the model requires that gene expression precedes DNA replication, it predicts that during selection, new mutants will arise from damage only to the transcribed DNA strand. As a test, we used a lacZ amber mutant of Escherichia coli that can revert by nitrous acid-induced deamination of adenine residues on either strand of the TAG stop codon, each causing different DNA mutations. When stationary-phase, mutagenized cells were grown in rich broth before being plated on lactose-selective media, only non-transcribed strand mutations appeared in the revertants. This result was consistent with the known high sensitivity to deamination of the single-stranded DNA in a transcription bubble, and it provided an important control because it demonstrated that the genetic system we would use to detect transcribed-strand mutations could also detect a bias toward the non-transcribed strand. When residual lacZ transcription was blocked beforehand by catabolite repression, both strands were mutated about equally, but if revertants were selected immediately after nitrous acid exposure, transcribed-strand mutations predominated among the revertants, implicating retromutagenesis as the mechanism. This result was not affected by gene orientation. Retromutagenesis is apt to be a universal method of evolutionary adaptation, which enables the emergence of new mutants from mutations acquired during counterselection rather than beforehand, and it may have roles in processes as diverse as the development of antibiotic resistance and neoplasia. The basic principle of neo-Darwinian genetics is that mutations occurring during growth enable the subsequent survival of the mutants under selective environmental conditions. However, new mutants can arise from a non-growing bacterial population during selection in an apparently Lamarckian way. The phenomenon is called adaptive mutation. In one suggested pathway, retromutagenesis, a damaged gene produces a mutant protein that enables enough growth for a mutant gene to be copied onto daughter chromosomes. This hypothesis is supported by evidence that, in several experimental systems, a damaged gene can produce a mutant protein rather than no protein at all, and that both RNA and DNA polymerase will pair the same base with a lesion. Because this model requires gene expression before DNA synthesis, a third feature is predicted: in a non-growing population, adaptive mutations will occur preferentially on the transcribed strand of a gene. In this paper, we describe a bacterial genetic system that can distinguish between mutations occurring on either DNA strand, and we use it to confirm this prediction. The findings enhance our general understanding of evolution in all organisms, the majority of which are in a non-growing state most of the time.
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Crystal structure of E. coli endonuclease V, an essential enzyme for deamination repair. Sci Rep 2015; 5:12754. [PMID: 26244280 PMCID: PMC4650699 DOI: 10.1038/srep12754] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 07/03/2015] [Indexed: 12/26/2022] Open
Abstract
Endonuclease V (EndoV) is a ubiquitous protein present in all three kingdoms of life, responsible for the specific cleavages at the second phosphodiester bond 3’ to inosine. E. coli EndoV (EcEndoV) is the first member discovered in the EndoV family. It is a small protein with a compact gene organization, yet with a wide spectrum of substrate specificities. However, the structural basis of its substrate recognition is not well understood. In this study, we determined the 2.4 Å crystal structure of EcEndoV. The enzyme preserves the general ‘RNase H-like motif’ structure. Two subunits are almost fully resolved in the asymmetric unit, but they are not related by any 2-fold axes. Rather, they establish “head-to-shoulder” contacts with loose interactions between each other. Mutational studies show that mutations that disrupt the association mode of the two subunits also decrease the cleavage efficiencies of the enzyme. Further biochemical studies suggest that EcEndoV is able to bind to single-stranded, undamaged DNA substrates without sequence specificity, and forms two types of complexes in a metal-independent manner, which may explain the wide spectrum of substrate specificities of EcEndoV.
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EndoQ and EndoV work individually for damaged DNA base repair in Pyrococcus furiosus. Biochimie 2015; 118:264-9. [PMID: 26116888 DOI: 10.1016/j.biochi.2015.06.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2015] [Accepted: 06/19/2015] [Indexed: 12/11/2022]
Abstract
Base deamination is a typical form of DNA damage, and it must be repaired quickly to maintain the genome integrity of living organisms. Endonuclease Q (EndoQ), recently found in the hyperthermophilic archaea, is an enzyme that cleaves the phosphodiester bond 5' from the damaged nucleotide in the DNA strand, and may primarily function to start the repair process for the damaged bases. Endonuclease V (EndoV) also hydrolyzes the second phosphodiester bond 3' from the damaged nucleotide, although the hyperthermophilic archaeal EndoV is a strictly hypoxanthine-specific endonuclease. To understand the relationships of the EndoQ and EndoV functions in hyperthermophilic archaea, we analyzed their interactions in hypoxanthine repair. EndoQ and EndoV do not directly interact with each other in either the presence or absence of DNA. However, EndoQ and EndoV individually worked on deoxyinosine (dI)-containing DNA at each cleavage site. EndoQ has higher affinity to dI-containing DNA than EndoV, and cells produce higher amounts of EndoQ, as compared to EndoV. These data support the proposal that EndoQ primarily functions for, at least, dI-containing DNA.
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Ishino Y, Narumi I. DNA repair in hyperthermophilic and hyperradioresistant microorganisms. Curr Opin Microbiol 2015; 25:103-12. [PMID: 26056771 DOI: 10.1016/j.mib.2015.05.010] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 04/22/2015] [Accepted: 05/20/2015] [Indexed: 10/23/2022]
Abstract
The genome of a living cell is continuously under attack by exogenous and endogenous genotoxins. Especially, life at high temperature inflicts additional stress on genomic DNA, and very high rates of potentially mutagenic DNA lesions, including deamination, depurination, and oxidation, are expected. However, the spontaneous mutation rates in hyperthermophiles are similar to that in Escherichia coli, and it is interesting to determine how the hyperthermophiles preserve their genomes under such grueling environmental conditions. In addition, organisms with extremely radioresistant phenotypes are targets for investigating special DNA repair mechanisms in extreme environments. Multiple DNA repair mechanisms have evolved in all organisms to ensure genomic stability, by preventing impediments that result in genome destabilizing lesions.
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Affiliation(s)
- Yoshizumi Ishino
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, 6-10-1 Hakozaki, Fukuoka, Fukuoka 812-8581, Japan.
| | - Issay Narumi
- Radiation Microbiology Laboratory, Department of Life Sciences, Faculty of Life Sciences, Toyo University, 1-1-1 Izumino, Itakura, Gunma 374-0193, Japan
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Dalhus B, Alseth I, Bjørås M. Structural basis for incision at deaminated adenines in DNA and RNA by endonuclease V. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2015; 117:134-142. [PMID: 25824682 DOI: 10.1016/j.pbiomolbio.2015.03.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2014] [Revised: 03/19/2015] [Accepted: 03/20/2015] [Indexed: 01/15/2023]
Abstract
Deamination of the exocyclic amines in adenine, guanine and cytosine forms base lesions that may lead to mutations if not removed by DNA repair proteins. Prokaryotic endonuclease V (EndoV/Nfi) has long been known to incise DNA 3' to a variety of base lesions, including deaminated adenine, guanine and cytosine. Biochemical and genetic data implicate that EndoV is involved in repair of these deaminated bases. In contrast to DNA glycosylases that remove a series of modified/damaged bases in DNA by direct excision of the nucleobase, EndoV cleaves the DNA sugar phosphate backbone at the second phosphodiester 3' to the lesion without removing the deaminated base. Structural investigation of this unusual incision by EndoV has unravelled an enzyme with separate base lesion and active site pockets. A novel wedge motif was identified as a DNA strand-separation feature important for damage detection. Human EndoV appears inactive on DNA, but has been shown to incise various RNA substrates containing inosine. Inosine is the deamination product of adenosine and is frequently found in RNA. The structural basis for discrimination between DNA and RNA by human EndoV remains elusive.
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Affiliation(s)
- Bjørn Dalhus
- Department of Medical Biochemistry, Institute for Clinical Medicine, University of Oslo, PO Box 4950, Nydalen, N-0424 Oslo, Norway; Department of Microbiology, Clinic for Diagnostics and Intervention, Oslo University Hospital, Rikshospitalet, PO Box 4950, Nydalen, N-0424 Oslo, Norway.
| | - Ingrun Alseth
- Department of Microbiology, Clinic for Diagnostics and Intervention, Oslo University Hospital, Rikshospitalet, PO Box 4950, Nydalen, N-0424 Oslo, Norway
| | - Magnar Bjørås
- Department of Microbiology, Clinic for Diagnostics and Intervention, Oslo University Hospital, Rikshospitalet, PO Box 4950, Nydalen, N-0424 Oslo, Norway
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Shiraishi M, Ishino S, Yamagami T, Egashira Y, Kiyonari S, Ishino Y. A novel endonuclease that may be responsible for damaged DNA base repair in Pyrococcus furiosus. Nucleic Acids Res 2015; 43:2853-63. [PMID: 25694513 PMCID: PMC4357722 DOI: 10.1093/nar/gkv121] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
DNA is constantly damaged by endogenous and environmental influences. Deaminated adenine (hypoxanthine) tends to pair with cytosine and leads to the A:T→G:C transition mutation during DNA replication. Endonuclease V (EndoV) hydrolyzes the second phosphodiester bond 3′ from deoxyinosine in the DNA strand, and was considered to be responsible for hypoxanthine excision repair. However, the downstream pathway after EndoV cleavage remained unclear. The activity to cleave the phosphodiester bond 5′ from deoxyinosine was detected in a Pyrococcus furiosus cell extract. The protein encoded by PF1551, obtained from the mass spectrometry analysis of the purified fraction, exhibited the corresponding cleavage activity. A putative homolog from Thermococcus kodakarensis (TK0887) showed the same activity. Further biochemical analyses revealed that the purified PF1551 and TK0887 proteins recognize uracil, xanthine and the AP site, in addition to hypoxanthine. We named this endonuclease Endonuclease Q (EndoQ), as it may be involved in damaged base repair in the Thermococcals of Archaea.
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Affiliation(s)
- Miyako Shiraishi
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, Fukuoka 812-8581, Japan
| | - Sonoko Ishino
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, Fukuoka 812-8581, Japan
| | - Takeshi Yamagami
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, Fukuoka 812-8581, Japan
| | - Yuriko Egashira
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, Fukuoka 812-8581, Japan
| | - Shinichi Kiyonari
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, Fukuoka 812-8581, Japan
| | - Yoshizumi Ishino
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, Fukuoka 812-8581, Japan
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Zhang Z, Hao Z, Wang Z, Li Q, Xie W. Structure of human endonuclease V as an inosine-specific ribonuclease. ACTA ACUST UNITED AC 2014; 70:2286-94. [PMID: 25195743 DOI: 10.1107/s139900471401356x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2014] [Accepted: 06/11/2014] [Indexed: 11/10/2022]
Abstract
The 6-aminopurine ring of adenosine (A) can be deaminated to form the 6-oxopurine of inosine (I). Endonuclease Vs (EndoVs) are inosine-specific nucleases that cleave at the second phosphodiester bond 3' to inosine. EndoV proteins are highly conserved in all domains of life, but the bacterial and human enzymes seem to display distinct substrate preferences. While the bacterial enzymes exhibit high cleavage efficiency on various nucleic acid substrates, human EndoV (hEndoV) is most active towards ssRNA but is much less active towards other substrates. However, the structural basis of substrate recognition by hEndoV is not well understood. In this study, the 2.3 Å resolution crystal structure of hEndoV was determined and its unusual RNA-cleaving properties were investigated. The enzyme preserves the general `RNase H-like' structure, especially in the wedge motif, the metal-binding site and the hypoxanthine-binding pocket. hEndoV also features several extra insertions and a characteristic four-cysteine motif, in which Cys227 and Cys228, two cysteines that are highly conserved in higher eukaryotes, play important roles in catalysis. The structure presented here helps in understanding the substrate preference of hEndoV catalysis.
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Affiliation(s)
- Zhemin Zhang
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory for Biocontrol, School of Life Sciences, The Sun Yat-Sen University, Guangzhou 510275, People's Republic of China
| | - Zhitai Hao
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory for Biocontrol, School of Life Sciences, The Sun Yat-Sen University, Guangzhou 510275, People's Republic of China
| | - Zhong Wang
- Centre for Cellular and Structural Biology, The Sun Yat-Sen University, 132 East Circle Road, University City, Guangzhou 510006, People's Republic of China
| | - Qing Li
- Centre for Cellular and Structural Biology, The Sun Yat-Sen University, 132 East Circle Road, University City, Guangzhou 510006, People's Republic of China
| | - Wei Xie
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory for Biocontrol, School of Life Sciences, The Sun Yat-Sen University, Guangzhou 510275, People's Republic of China
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Human endonuclease V is a ribonuclease specific for inosine-containing RNA. Nat Commun 2014; 4:2273. [PMID: 23912718 PMCID: PMC3741642 DOI: 10.1038/ncomms3273] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 07/09/2013] [Indexed: 01/21/2023] Open
Abstract
Deamination of DNA bases can create missense mutations predisposing humans to cancer and also interfere with other basic molecular genetic processes; this deamination generates deoxyinosine from deoxyadenosine. In Escherichia coli, the highly conserved endonuclease V is involved in alternative excision repair that removes deoxyinosine from DNA. However, its exact activities and roles in humans are unknown. Here we characterize the FLJ35220 protein, the human homologue of E. coli endonuclease V, hEndoV as a ribonuclease specific for inosine-containing RNA. hEndoV preferentially binds to RNA and efficiently hydrolyses the second phosphodiester bond located 3′ to the inosine in unpaired inosine-containing ssRNA regions in dsRNA. It localizes to the cytoplasm in cells. The ribonuclease activity is promoted by Tudor staphylococcal nuclease and detected on inosine-containing dsRNA created by the action of adenosine deaminases acting on RNA. These results demonstrate that hEndoV controls the fate of inosine-containing RNA in humans. In Escherichia coli, the highly conserved enzyme endonuclease V has a role in DNA repair. Here the authors show that human endonuclease V is an inosine 3' endoribonuclease and that Tudor Staphylococcal nuclease enhances this activity, suggesting a role for human endonuclease V in RNA metabolism.
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Vik ES, Nawaz MS, Strøm Andersen P, Fladeby C, Bjørås M, Dalhus B, Alseth I. Endonuclease V cleaves at inosines in RNA. Nat Commun 2014; 4:2271. [PMID: 23912683 PMCID: PMC3741635 DOI: 10.1038/ncomms3271] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 07/09/2013] [Indexed: 01/05/2023] Open
Abstract
Endonuclease V orthologues are highly conserved proteins found in all kingdoms of life. While the prokaryotic enzymes are DNA repair proteins for removal of deaminated adenosine (inosine) from the genome, no clear role for the eukaryotic counterparts has hitherto been described. Here we report that human endonuclease V (ENDOV) and also Escherichia coli endonuclease V are highly active ribonucleases specific for inosine in RNA. Inosines are normal residues in certain RNAs introduced by specific deaminases. Adenosine-to-inosine editing is essential for proper function of these transcripts and defects are linked to various human disease. Here we show that human ENDOV cleaves an RNA substrate containing inosine in a position corresponding to a biologically important site for deamination in the Gabra-3 transcript of the GABA(A) neurotransmitter. Further, human ENDOV specifically incises transfer RNAs with inosine in the wobble position. This previously unknown RNA incision activity may suggest a role for endonuclease V in normal RNA metabolism.
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Affiliation(s)
- Erik Sebastian Vik
- Department of Microbiology, Oslo University Hospital HF and University of Oslo, Rikshospitalet, PO Box 4950 Nydalen, 0424 Oslo, Norway
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50
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Kiyonari S, Egashira Y, Ishino S, Ishino Y. Biochemical characterization of endonuclease V from the hyperthermophilic archaeon, Pyrococcus furiosus. J Biochem 2014; 155:325-33. [PMID: 24535600 DOI: 10.1093/jb/mvu010] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Endonuclease V (Endo V) is a DNA repair enzyme that recognizes deoxyinosine and cleaves the second phosphodiester bond on the 3' side of the deaminated base lesion. A database search revealed the presence of homologous genes for Endo V in most archaeal species, but the absence in some methanogenic species. We cloned a gene encoding the sequence homologous to Escherichia coli Endo V from the genome of the hyperthermophilic euryarchaeon, Pyrococcus furiosus and purified gene product (PfuEndoV) to homogeneity. In vitro characterization showed that PfuEndoV possesses specific endonuclease activity for the deoxyinosine-containing DNA strand. The activity of the enzyme was maximal at 90°C. Stable complex formation between PfuEndoV and nicked DNA produced by the cleavage reaction was detected by gel mobility shift assays. The molecular mechanisms of the inosine repair pathway including Endo V in the archaeal cells are discussed. Interestingly, PfuEndoV cleaved inosine-containing RNA strands as well as DNA substrates. PfuEndoV may also be involved in RNA metabolism.
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Affiliation(s)
- Shinichi Kiyonari
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, Fukuoka 812-8581, Japan
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