1
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Kaur R, Wetmore SD. Is Metal Stabilization of the Leaving Group Required or Can Lysine Facilitate Phosphodiester Bond Cleavage in Nucleic Acids? A Computational Study of EndoV. J Chem Inf Model 2024; 64:944-959. [PMID: 38253321 DOI: 10.1021/acs.jcim.3c01775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Endonuclease V (EndoV) is a single-metal-dependent enzyme that repairs deaminated DNA nucleobases in cells by cleaving the phosphodiester bond, and this enzyme has proven to be a powerful tool in biotechnology and medicine. The catalytic mechanism used by EndoV must be understood to design new disease detection and therapeutic solutions and further exploit the enzyme in interdisciplinary applications. This study has used a mixed molecular dynamics (MD) and quantum mechanics/molecular mechanics (QM/MM) approach to compare eight distinct catalytic pathways and provides the first proposed mechanism for bacterial EndoV. The calculations demonstrate that mechanisms involving either direct or indirect metal coordination to the leaving group of the substrate previously proposed for other nucleases are unlikely for EndoV, regardless of the general base (histidine, aspartate, and substrate phosphate moiety). Instead, distinct catalytic pathways are characterized for EndoV that involve K139 stabilizing the leaving group, a metal-coordinated water stabilizing the transition structure, and either H214 or a substrate phosphate group activating the water nucleophile. In silico K139A and H214A mutational results support the newly proposed roles of these residues. Although this is a previously unseen combination of general base, general acid, and metal-binding architecture for a one-metal-dependent endonuclease, our proposed catalytic mechanisms are fully consistent with experimental kinetic, structural, and mutational data. In addition to substantiating a growing body of literature, suggesting that one metal is enough to catalyze P-O bond cleavage in nucleic acids, this new fundamental understanding of the catalytic function will promote the exploration of new and improved applications of EndoV.
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Affiliation(s)
- Rajwinder Kaur
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive West, Lethbridge, Alberta T1K 3M4, Canada
| | - Stacey D Wetmore
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive West, Lethbridge, Alberta T1K 3M4, Canada
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2
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Wu M, Ma G, Lin Y, Oger P, Cao P, Zhang L. Biochemical Characterization and Mutational Studies of Endonuclease Q from the Hyperthermophilic Euryarchaeon Thermococcus gammatolerans. DNA Repair (Amst) 2023; 126:103490. [PMID: 37028219 DOI: 10.1016/j.dnarep.2023.103490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 03/25/2023] [Accepted: 03/29/2023] [Indexed: 04/03/2023]
Abstract
Endonuclease Q (EndoQ) can effectively cleave DNA containing deaminated base(s), thus providing a potential pathway for repair of deaminated DNA. EndoQ is ubiquitous in some Archaea, especially in Thermococcales, and in a small group of bacteria. Herein, we report biochemical characteristics of EndoQ from the hyperthermophilic euryarchaeon Thermococcus gammatolerans (Tga-EndoQ) and the roles of its six conserved residues in DNA cleavage. The enzyme can cleave uracil-, hypoxanthine-, and AP (apurinic/apyrimidinic) site-containing DNA with varied efficiencies at high temperature, among which uracil-containing DNA is its most preferable substrate. Additionally, the enzyme displays maximum cleavage efficiency at above 70 oC and pH 7.0 ∼ 8.0. Furthermore, Tga-EndoQ still retains 85% activity after heated at 100 oC for 2 hrs, suggesting that the enzyme is extremely thermostable. Moreover, the Tga-EndoQ activity is independent of a divalent ion and NaCl. Mutational data demonstrate that residues E167 and H195 in Tga-EndoQ are essential for catalysis since the E167A and H195A mutants completely abolish the cleavage activity. Besides, residues S18 and R204 in Tga-EndoQ are involved in catalysis due to the reduced activities observed for the S18A and R204A mutants. Overall, our work has augmented biochemical function of archaeal EndoQ and provided insight into its catalytic mechanism.
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Affiliation(s)
- Mai Wu
- College of Environmental Science and Engineering, Yangzhou University, Yangzhou City, China
| | - Guangyu Ma
- College of Environmental Science and Engineering, Yangzhou University, Yangzhou City, China
| | - Yushan Lin
- College of Environmental Science and Engineering, Yangzhou University, Yangzhou City, China
| | - Philippe Oger
- Université de Lyon, INSA de Lyon, CNRS UMR, 5240 Lyon, France
| | - Peng Cao
- Faculty of Environment and Life, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing 100124, China.
| | - Likui Zhang
- College of Environmental Science and Engineering, Yangzhou University, Yangzhou City, China.
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3
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Zheng X, Chang S, Liu Y, Dai X, You C. Human Mitochondrial Protein HSPD1 Binds to and Regulates the Repair of Deoxyinosine in DNA. J Proteome Res 2023; 22:1339-1346. [PMID: 36852893 DOI: 10.1021/acs.jproteome.2c00854] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
The generation of deoxyinosine (dI) in DNA is one of the most important sources of genetic mutations, which may lead to cancer and other human diseases. A further understanding of the biological consequences of dI necessitates the identification and functional characterizations of dI-binding proteins. Herein, we employed a mass spectrometry-based proteomics approach to detect the cellular proteins that may sense the presence of dI in DNA. Our results demonstrated that human mitochondrial heat shock protein 60 (HSPD1) can interact with dI-bearing DNA. We further demonstrated the involvement of HSPD1 in the sodium nitrite-induced DNA damage response and in the modulation of dI levels in vitro and in human cells. Together, these findings revealed HSPD1 as a novel dI-binding protein that may play an important role in the mitochondrial DNA damage control in human cells.
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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, Hunan 410082, China
| | - Sijia Chang
- 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, Hunan 410082, China
| | - Yini Liu
- 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, Hunan 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, Hunan 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, Hunan 410082, China
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4
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Biochemical and mutational studies of an endonuclease V from the hyperthermophilic crenarchaeon Sulfolobus islandicus REY15A. World J Microbiol Biotechnol 2023; 39:90. [PMID: 36752840 DOI: 10.1007/s11274-023-03526-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Accepted: 01/16/2023] [Indexed: 02/09/2023]
Abstract
Endonuclease V (EndoV), which is widespread in bacteria, eukarya and Archaea, can cleave hypoxanthine (Hx)-containing DNA or RNA strand, and play an essential role in Hx repair. However, our understanding on archaeal EndoV's function remains incomplete. The model archaeon Sulfolobus islandicus REY15A encodes a putative EndoV protein (Sis-EndoV). Herein, we probed the biochemical characteristics of Sis-EndoV and dissected the roles of its seven conserved residues. Our biochemical data demonstrate that Sis-EndoV displays maximum cleavage efficiency at above 60 °C and at pH 7.0-9.0, and the enzyme activity is dependent on a divalent metal ion, among which Mg2+ is optimal. Importantly, we first measured the activation energy for cleaving Hx-containing ssDNA by Sis-EndoV to be 9.6 ± 0.8 kcal/mol by kinetic analyses, suggesting that chemical catalysis might be a rate-limiting step for catalysis. Mutational analyses show that residue D38 in Sis-EndoV is essential for catalysis, but has no role in DNA binding. Furthermore, we first revealed that residues Y41 and D189 in Sis-EndoV are involved in both DNA cleavage and DNA binding, but residues F77, H103, K156 and F161 are only responsible for DNA binding.
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5
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Li J, Yang Y, Chang C, Cao W. DR0022 from Deinococcus radiodurans is an acid uracil-DNA glycosylase. FEBS J 2022; 289:6420-6434. [PMID: 35607831 PMCID: PMC9796141 DOI: 10.1111/febs.16533] [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: 03/11/2022] [Revised: 04/08/2022] [Accepted: 05/23/2022] [Indexed: 01/02/2023]
Abstract
Uracil-DNA glycosylase (UDG) initiates base excision repair (BER) by removing damaged or modified nucleobases during DNA repair or mammalian demethylation. The UDG superfamily consists of at least six families with a variety of catalytic specificities and functions. Deinococcus radiodurans, an extreme radiation resistant bacterium, contains multiple members of UDG enzymes within its genome. The present study reveals that the putative protein, DR0022, is a uracil-DNA glycosylase that requires acidic conditions for its glycosylase activity, which is the first case of such an enzyme within the UDG superfamily. The key residues in the catalytic motifs are investigated by biochemical, enzyme kinetics, and de novo structural prediction, as well as molecular modeling analyses. The structural and catalytic roles of several distinct residues are discussed in light of predicted and modeled DR0022 glycosylase structures. The spontaneous mutation rate analysis performed in a dr0022 deficient D. radiodurans strain indicated that the dr0022 gene plays a role in mutation prevention. Furthermore, survival rate analysis in a dr0022 deficient D. radiodurans strain demonstrated its role in stress resistance, including γ-irradiation. Additionally, the novel acid UDG activity in relationship to its in vivo roles is discussed. This work underscores the functional diversity in the UDG superfamily.
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Affiliation(s)
- Jing Li
- Department of Genetics and BiochemistryClemson UniversityClemsonSCUSA
| | - Ye Yang
- Department of Genetics and BiochemistryClemson UniversityClemsonSCUSA
| | - Chenyan Chang
- Department of Genetics and BiochemistryClemson UniversityClemsonSCUSA
| | - Weiguo Cao
- Department of Genetics and BiochemistryClemson UniversityClemsonSCUSA
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6
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A novel Family V uracil DNA glycosylase from Sulfolobus islandicus REY15A. DNA Repair (Amst) 2022; 120:103420. [DOI: 10.1016/j.dnarep.2022.103420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 10/09/2022] [Accepted: 10/16/2022] [Indexed: 11/18/2022]
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7
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Shiraishi M, Hidaka M, Iwai S. Endonuclease V from the archaeon Thermococcus kodakarensis is an inosine-specific ribonuclease. Biosci Biotechnol Biochem 2022; 86:313-320. [PMID: 34928335 DOI: 10.1093/bbb/zbab219] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 12/11/2021] [Indexed: 11/14/2022]
Abstract
Endonuclease V (EndoV) is an inosine-specific endonuclease which is highly conserved in all domains of life: Bacteria, Archaea, and Eukarya; and, therefore, may play an important role in nucleic acid processes. It is currently thought that bacterial EndoVs are involved in DNA repair, while eukaryotic EndoVs are involved in RNA editing based on the differences in substrate preferences. However, the role of EndoV proteins, particularly in the archaeal domain, is still poorly understood. Here, we explored the biochemical properties of EndoV from the hyperthermophilic archaeon Thermococcus kodakarensis (TkoEndoV). We show that TkoEndoV has a strong preference for RNA over DNA. Further, we synthesized 1-methylinosine-containing RNA that is a simple TΨC loop mimic of archaeal tRNA and found that TkoEndoV discriminates between 1-methylinosine and inosine, and selectively acts on inosine. Our findings suggest a potential role of archaeal EndoV in the regulation of inosine-containing RNA.
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Affiliation(s)
- Miyako Shiraishi
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan
| | - Michihi Hidaka
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan
| | - Shigenori Iwai
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan
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8
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Lin T, Zhang L, Wu M, Jiang D, Li Z, Yang Z. Repair of Hypoxanthine in DNA Revealed by DNA Glycosylases and Endonucleases From Hyperthermophilic Archaea. Front Microbiol 2021; 12:736915. [PMID: 34531846 PMCID: PMC8438529 DOI: 10.3389/fmicb.2021.736915] [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: 07/06/2021] [Accepted: 08/04/2021] [Indexed: 11/13/2022] Open
Abstract
Since hyperthermophilic Archaea (HA) thrive in high-temperature environments, which accelerate the rates of deamination of base in DNA, their genomic stability is facing a severe challenge. Hypoxanthine (Hx) is one of the common deaminated bases in DNA. Generally, replication of Hx in DNA before repaired causes AT → GC mutation. Biochemical data have demonstrated that 3-methyladenine DNA glycosylase II (AlkA) and Family V uracil DNA glycosylase (UDG) from HA could excise Hx from DNA, thus triggering a base excision repair (BER) process for Hx repair. Besides, three endonucleases have been reported from HA: Endonuclease V (EndoV), Endonuclease Q (EndoQ), and Endonuclease NucS (EndoNucS), capable of cleaving Hx-containing DNA, thereby providing alternative pathways for Hx repair. Both EndoV and EndoQ could cleave one DNA strand with Hx, thus forming a nick and further initiating an alternative excision repair (AER) process for the follow-up repair. By comparison, EndoNucS cleaves both strands of Hx-containing DNA in a restriction endonuclease manner, thus producing a double-stranded break (DSB). This created DSB might be repaired by homologous recombination (HR) or by a combination activity of DNA polymerase (DNA pol), flap endonuclease 1 (FEN1), and DNA ligase (DNA lig). Herein, we reviewed the most recent advances in repair of Hx in DNA triggered by DNA glycosylases and endonucleases from HA, and proposed future research directions.
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Affiliation(s)
- Tan Lin
- College of Environmental Science and Engineering, Marine Science and Technology Institute, Yangzhou University, Yangzhou, China
| | - Likui Zhang
- College of Environmental Science and Engineering, Marine Science and Technology Institute, Yangzhou University, Yangzhou, China.,Guangling College, Yangzhou University, Yangzhou, China
| | - Mai Wu
- College of Environmental Science and Engineering, Marine Science and Technology Institute, Yangzhou University, Yangzhou, China
| | - Donghao Jiang
- College of Environmental Science and Engineering, Marine Science and Technology Institute, Yangzhou University, Yangzhou, China
| | - Zheng Li
- College of Plant Protection, Agricultural University of Hebei, Baoding, China
| | - Zhihui Yang
- College of Plant Protection, Agricultural University of Hebei, Baoding, China
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9
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Srinivasan S, Torres AG, Ribas de Pouplana L. Inosine in Biology and Disease. Genes (Basel) 2021; 12:600. [PMID: 33921764 PMCID: PMC8072771 DOI: 10.3390/genes12040600] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 04/13/2021] [Accepted: 04/15/2021] [Indexed: 02/06/2023] Open
Abstract
The nucleoside inosine plays an important role in purine biosynthesis, gene translation, and modulation of the fate of RNAs. The editing of adenosine to inosine is a widespread post-transcriptional modification in transfer RNAs (tRNAs) and messenger RNAs (mRNAs). At the wobble position of tRNA anticodons, inosine profoundly modifies codon recognition, while in mRNA, inosines can modify the sequence of the translated polypeptide or modulate the stability, localization, and splicing of transcripts. Inosine is also found in non-coding and exogenous RNAs, where it plays key structural and functional roles. In addition, molecular inosine is an important secondary metabolite in purine metabolism that also acts as a molecular messenger in cell signaling pathways. Here, we review the functional roles of inosine in biology and their connections to human health.
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Affiliation(s)
- Sundaramoorthy Srinivasan
- Institute for Research in Biomedicine, Barcelona Institute of Science and Technology, 08028 Barcelona, Catalonia, Spain; (S.S.); (A.G.T.)
| | - Adrian Gabriel Torres
- Institute for Research in Biomedicine, Barcelona Institute of Science and Technology, 08028 Barcelona, Catalonia, Spain; (S.S.); (A.G.T.)
| | - Lluís Ribas de Pouplana
- Institute for Research in Biomedicine, Barcelona Institute of Science and Technology, 08028 Barcelona, Catalonia, Spain; (S.S.); (A.G.T.)
- Catalan Institution for Research and Advanced Studies, 08010 Barcelona, Catalonia, Spain
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10
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Molecular characterization of EhAK6, an endonuclease V domain-containing aurora kinase protein from Entamoeba histolytica: Protein-protein interaction, docking and functional aspect. CURRENT RESEARCH IN BIOTECHNOLOGY 2021. [DOI: 10.1016/j.crbiot.2021.07.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
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11
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Jiang D, Zhang L, Dong K, Gong Y, Oger P. Biochemical characterization and mutational studies of a novel 3-methlyadenine DNA glycosylase II from the hyperthermophilic Thermococcus gammatolerans. DNA Repair (Amst) 2020; 97:103030. [PMID: 33360524 DOI: 10.1016/j.dnarep.2020.103030] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 11/14/2020] [Accepted: 11/30/2020] [Indexed: 02/02/2023]
Abstract
The hyperthermophilic and radioresistant euryarchaeon Thermococcus gammatolerans encodes a putative 3-methlyadenine DNA glycosylase II (Tg-AlkA). Herein, we report biochemical characterization and catalytic mechanism of Tg-AlkA. The recombinant Tg-AlkA can excise hypoxanthine (Hx) and 1-methlyadenine (1-meA) from dsDNA with varied efficiencies at high temperature. Notably, Tg-AlkA is a bi-functional glycosylase, which is sharply distinct from all the reported AlkAs. Biochemical data show that the optimal temperature and pH of Tg-AlkA for removing Hx from dsDNA are ca.70 °C and ca.7.0-8.0, respectively. Furthermore, the Tg-AlkA activity is independent of a divalent metal ion, and Mg2+ stimulates the Tg-AlkA activity whereas other divalent ions inhibit the enzyme activity with varied degrees. Mutational studies show that the Tg-AlkA W204A and D223A mutants abolish completely the excision activity, thereby suggesting that residues W204 and D223 are involved in catalysis. Surprisingly, the mutations of W204, D223, Y139 and W256 to alanine in Tg-AlkA lead to the increased affinity for binding DNA substrate with varied degrees, suggesting that these residues are flexible for conformational change of the enzyme. Therefore, Tg-AlkA is a novel AlkA that can remove Hx and 1-meA from dsDNA, thus providing insights into repair of deaminated and alkylated bases in DNA from hyperthermophilic Thermococcus.
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Affiliation(s)
- Donghao Jiang
- Marine Science & Technology Institute, College of Environmental Science and Engineering, Yangzhou University, China
| | - Likui Zhang
- Marine Science & Technology Institute, College of Environmental Science and Engineering, Yangzhou University, China; Guangling College, Yangzhou University, China.
| | - Kunming Dong
- Marine Science & Technology Institute, College of Environmental Science and Engineering, Yangzhou University, China
| | - Yong Gong
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, China.
| | - Philippe Oger
- Univ Lyon, INSA De Lyon, CNRS UMR 5240, Lyon, France.
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12
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Pérez-Arnaiz P, Dattani A, Smith V, Allers T. Haloferax volcanii-a model archaeon for studying DNA replication and repair. Open Biol 2020; 10:200293. [PMID: 33259746 PMCID: PMC7776575 DOI: 10.1098/rsob.200293] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 11/09/2020] [Indexed: 12/16/2022] Open
Abstract
The tree of life shows the relationship between all organisms based on their common ancestry. Until 1977, it comprised two major branches: prokaryotes and eukaryotes. Work by Carl Woese and other microbiologists led to the recategorization of prokaryotes and the proposal of three primary domains: Eukarya, Bacteria and Archaea. Microbiological, genetic and biochemical techniques were then needed to study the third domain of life. Haloferax volcanii, a halophilic species belonging to the phylum Euryarchaeota, has provided many useful tools to study Archaea, including easy culturing methods, genetic manipulation and phenotypic screening. This review will focus on DNA replication and DNA repair pathways in H. volcanii, how this work has advanced our knowledge of archaeal cellular biology, and how it may deepen our understanding of bacterial and eukaryotic processes.
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Affiliation(s)
| | | | | | - Thorsten Allers
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, UK
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13
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Sananmuang T, Puthier D, Nguyen C, Chokeshaiusaha K. Novel classifier orthologs of bovine and human oocytes matured in different melatonin environments. Theriogenology 2020; 156:82-89. [PMID: 32682179 DOI: 10.1016/j.theriogenology.2020.06.029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 06/25/2020] [Accepted: 06/25/2020] [Indexed: 12/30/2022]
Abstract
It has been demonstrated that melatonin influences the developmental competence of both in vivo and in vitro matured oocytes. It modulates oocyte-specific gene expression patterns among mammalian species. Due to differences among study systems, the identification of the classifier orthologs-the homologous genes related among mammals that could universally categorize oocytes matured in environments with varied melatonin levels is still limitedly studied. To gain insight into such orthologs, cross-species transcription profiling meta-analysis of in vitro matured bovine oocytes and in vivo matured human oocytes in low and high melatonin environments was demonstrated in the current study. RNA-Seq data of bovine and human oocytes were retrieved from the Sequence Read Archive database and pre-processed. The used datasets of bovine oocytes obtained from culturing in the absence of melatonin and human oocytes from old patients were regarded as oocytes in the low melatonin environment (Low). Datasets from bovine oocytes cultured in 10-9 M melatonin and human oocytes from young patients were considered as oocytes in the high melatonin environment (High). Candidate orthologs differentially expressed between Low and High melatonin environments were selected by a linear model, and were further verified by Zero-inflated regression analysis. Support Vector Machine (SVM) was applied to determine the potentials of the verified orthologs as classifiers of melatonin environments. According to the acquired results, linear model analysis identified 284 candidate orthologs differentially expressed between Low and High melatonin environments. Among them, only 15 candidate orthologs were verified by Zero-inflated regression analysis (FDR ≤ 0.05). Utilization of the verified orthologs as classifiers in SVM resulted in the precise classification of oocyte learning datasets according to their melatonin environments (Misclassification rates < 0.18, area under curves > 0.9). In conclusion, the cross-species RNA-Seq meta-analysis to identify novel classifier orthologs of matured oocytes under different melatonin environments was successfully demonstrated in this study-delivering candidate orthologs for future studies at biological levels. Such verified orthologs might provide valuable evidence about melatonin sufficiency in target oocytes-by which, the decision on melatonin supplementation could be implied.
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Affiliation(s)
- Thanida Sananmuang
- Rajamangala University of Technology Tawan-OK, Faculty of Veterinary Medicine, Chonburi, Thailand
| | - Denis Puthier
- Aix-Marseille Université, INSERM UMR 1090, TAGC, Marseille, France
| | - Catherine Nguyen
- Aix-Marseille Université, INSERM UMR 1090, TAGC, Marseille, France
| | - Kaj Chokeshaiusaha
- Rajamangala University of Technology Tawan-OK, Faculty of Veterinary Medicine, Chonburi, Thailand.
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14
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Barrett M, Hand CK, Shanahan F, Murphy T, O'Toole PW. Mutagenesis by Microbe: the Role of the Microbiota in Shaping the Cancer Genome. Trends Cancer 2020; 6:277-287. [PMID: 32209443 DOI: 10.1016/j.trecan.2020.01.019] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 01/26/2020] [Accepted: 01/27/2020] [Indexed: 02/06/2023]
Abstract
Cancers arise through the process of somatic evolution fueled by the inception of somatic mutations. We lack a complete understanding of the sources of these somatic mutations. Humans host a vast repertoire of microbes collectively known as the microbiota. The microbiota plays a role in altering the tumor microenvironment and proliferation. In addition, microbes have been shown to elicit DNA damage which provides the driver for somatic mutations. An understanding of microbiota-driven mutational mechanisms would contribute to a more complete understanding of the origins of the cancer genome. Here, we review the modes by which microbes stimulate DNA damage and the effect of these phenomena upon the cancer genomic architecture, specifically in the form of mutational spectra and mutational signatures.
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Affiliation(s)
- Maurice Barrett
- APC Microbiome Ireland, University College Cork, National University of Ireland, Cork, Ireland; School of Microbiology, University College Cork, National University of Ireland, Cork, Ireland
| | - Collette K Hand
- Department of Pathology, University College Cork, Cork, Ireland
| | - Fergus Shanahan
- APC Microbiome Ireland, University College Cork, National University of Ireland, Cork, Ireland; Department of Medicine, University College Cork, National University of Ireland, Cork, Ireland
| | - Thomas Murphy
- Department of Surgery, Mercy University Hospital, Cork, Ireland
| | - Paul W O'Toole
- APC Microbiome Ireland, University College Cork, National University of Ireland, Cork, Ireland; School of Microbiology, University College Cork, National University of Ireland, Cork, Ireland.
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15
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Zhang L, Shi H, Gan Q, Wang Y, Wu M, Yang Z, Oger P, Zheng J. An alternative pathway for repair of deaminated bases in DNA triggered by archaeal NucS endonuclease. DNA Repair (Amst) 2019; 85:102734. [PMID: 31704332 DOI: 10.1016/j.dnarep.2019.102734] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2019] [Revised: 10/10/2019] [Accepted: 10/10/2019] [Indexed: 01/09/2023]
Abstract
Recent studies show that NucS endonucleases participate in mismatch repair in several archaea and bacteria. However, the function of archaeal NucS endonucleases has not been completely clarified. Here, we describe a NucS endonuclease from the hyperthermophilic and radioresistant archaeon Thermococcus gammatolerans (Tga NucS) that can cleave uracil (U)- and hypoxanthine (I)-containing dsDNA at 80 °C. Biochemical evidence shows that the cleavage sites of the enzyme are at the second phosphodiester on the 5'- site of U or I, and at the third phosphodiester on the 5'-site of the opposite base of U or I, creating a double strand break with a 4-nt 5'-overhang.The ends of the cleaved product of Tga NucS are ligatable, possessing 5'-phosphate and 3'-hydroxyl termini, which can be utilized by DNA repair proteins or enzymes. Tga NucS displays a preference for U/G- and I/T-containing dsDNA over other pairs with U or I, suggesting that the enzyme is responsible for repair of U and I in DNA that arise from deamination. Biochemical characterization of cleaving U- and I-containing DNA by Tga NucS was also investigated. The DNA-binding results show that the enzyme exhibits a higher affinity for normal, U- and I-containing dsDNA than for normal, U- and I-containing ssDNA. Therefore, we present an alternative pathway for repair of deaminated bases in DNA triggered by archaeal NucS endonuclease in hyperthermophilic archaea.
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Affiliation(s)
- Likui Zhang
- Marine Science & Technology Institute, Department of Environmental Science and Engineering, Yangzhou University, China; Guangling College, Yangzhou University, China.
| | - Haoqiang Shi
- Marine Science & Technology Institute, Department of Environmental Science and Engineering, Yangzhou University, China
| | - Qi Gan
- Marine Science & Technology Institute, Department of Environmental Science and Engineering, Yangzhou University, China
| | - Yuxiao Wang
- Marine Science & Technology Institute, Department of Environmental Science and Engineering, Yangzhou University, China
| | - Mai Wu
- Marine Science & Technology Institute, Department of Environmental Science and Engineering, Yangzhou University, China
| | - Zhihui Yang
- College of Plant Protection, Agricultural University of Hebei, Baoding City, Hebei Province 071001, China.
| | - Philippe Oger
- Univ Lyon, INSA de Lyon, CNRS UMR 5240, Villeurbanne, France.
| | - Jianting Zheng
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
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16
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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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17
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Miyazono KI, Ishino S, Makita N, Ito T, Ishino Y, Tanokura M. Crystal structure of the novel lesion-specific endonuclease PfuEndoQ from Pyrococcus furiosus. Nucleic Acids Res 2019; 46:4807-4818. [PMID: 29660024 PMCID: PMC5961232 DOI: 10.1093/nar/gky261] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 03/28/2018] [Indexed: 02/03/2023] Open
Abstract
Because base deaminations, which are promoted by high temperature, ionizing radiation, aerobic respiration and nitrosative stress, produce mutations during replication, deaminated bases must be repaired quickly to maintain genome integrity. Recently, we identified a novel lesion-specific endonuclease, PfuEndoQ, from Pyrococcus furiosus, and PfuEndoQ may be involved in the DNA repair pathway in Thermococcales of Archaea. PfuEndoQ recognizes a deaminated base and cleaves the phosphodiester bond 5' of the lesion site. To elucidate the structural basis of the substrate recognition and DNA cleavage mechanisms of PfuEndoQ, we determined the structure of PfuEndoQ using X-ray crystallography. The PfuEndoQ structure and the accompanying biochemical data suggest that PfuEndoQ recognizes a deaminated base using a highly conserved pocket adjacent to a Zn2+-binding site and hydrolyses a phosphodiester bond using two Zn2+ ions. The PfuEndoQ-DNA complex is stabilized by a Zn-binding domain and a C-terminal helical domain, and the complex may recruit downstream proteins in the DNA repair pathway.
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Affiliation(s)
- Ken-Ichi Miyazono
- Laboratory of Basic Science on Healthy Longevity, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Sonoko Ishino
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, and Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan
| | - Naruto Makita
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, and Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan
| | - Tomoko Ito
- Laboratory of Basic Science on Healthy Longevity, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Yoshizumi Ishino
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, and Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan
| | - Masaru Tanokura
- Laboratory of Basic Science on Healthy Longevity, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
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18
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Thomas AK, Preetha S, Omanakuttan A, Vidyullata L, Ashokan A, Rajachandran V, Chattopadhyay S. Mutational convergence acts as a major player in adaptive parallel evolution of Shigella spp. Sci Rep 2019; 9:3252. [PMID: 30824790 PMCID: PMC6397287 DOI: 10.1038/s41598-019-39810-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 01/25/2019] [Indexed: 12/17/2022] Open
Abstract
Shigella spp., emerging from multiple origins of Escherichia coli, poses a significant health threat as a causative agent of bacillary dysentery. While multiple serotypes of four different species have evolved via independent lineages, Shigella spp. are designated as a single pathotype, primarily because of their common mode of pathogenesis. Convergent horizontal transfer events have so far been attributed to the commonalities in the evolution of virulence across diverse lineages. However, the role of mutational convergence in such parallel evolution is not yet well understood. Here we have carried out a genome-wide analysis of Shigella strains from all four species to detect the core genes (i.e. the ones present in all analyzed strains) acquiring convergent mutations of evolutionarily recent origin. Simulation studies show non-neutral accumulation of these convergent mutations across species, suggesting their adaptive role in the evolution of Shigella virulence. S. dysenteriae strain 197, representing highly virulent type 1 (Sd1) clone, carries excessively high number of core genes with recent convergent mutations compared to other analyzed strains. We propose that this high frequency of adaptive convergence in S. dysenteriae strain 197 could be linked to recent re-emergence of the Sd1 clone and its increased resistance to antimicrobials.
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Affiliation(s)
- Achsah K Thomas
- School of Biotechnology, Amrita Vishwa Vidyapeetham, Kollam, 690 525, Kerala, India
| | - Sruthy Preetha
- School of Biotechnology, Amrita Vishwa Vidyapeetham, Kollam, 690 525, Kerala, India
| | - Anjana Omanakuttan
- School of Biotechnology, Amrita Vishwa Vidyapeetham, Kollam, 690 525, Kerala, India
| | - Lakkaraju Vidyullata
- School of Biotechnology, Amrita Vishwa Vidyapeetham, Kollam, 690 525, Kerala, India
| | - Anjaly Ashokan
- School of Biotechnology, Amrita Vishwa Vidyapeetham, Kollam, 690 525, Kerala, India
| | - Vyshakh Rajachandran
- School of Biotechnology, Amrita Vishwa Vidyapeetham, Kollam, 690 525, Kerala, India
| | - Sujay Chattopadhyay
- School of Biotechnology, Amrita Vishwa Vidyapeetham, Kollam, 690 525, Kerala, India.
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19
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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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20
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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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21
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Foster PL, Niccum BA, Popodi E, Townes JP, Lee H, MohammedIsmail W, Tang H. Determinants of Base-Pair Substitution Patterns Revealed by Whole-Genome Sequencing of DNA Mismatch Repair Defective Escherichia coli. Genetics 2018; 209:1029-1042. [PMID: 29907647 PMCID: PMC6063221 DOI: 10.1534/genetics.118.301237] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 06/14/2018] [Indexed: 11/18/2022] Open
Abstract
Mismatch repair (MMR) is a major contributor to replication fidelity, but its impact varies with sequence context and the nature of the mismatch. Mutation accumulation experiments followed by whole-genome sequencing of MMR-defective Escherichia coli strains yielded ≈30,000 base-pair substitutions (BPSs), revealing mutational patterns across the entire chromosome. The BPS spectrum was dominated by A:T to G:C transitions, which occurred predominantly at the center base of 5'NAC3'+5'GTN3' triplets. Surprisingly, growth on minimal medium or at low temperature attenuated these mutations. Mononucleotide runs were also hotspots for BPSs, and the rate at which these occurred increased with run length. Comparison with ≈2000 BPSs accumulated in MMR-proficient strains revealed that both kinds of hotspots appeared in the wild-type spectrum and so are likely to be sites of frequent replication errors. In MMR-defective strains transitions were strand biased, occurring twice as often when A and C rather than T and G were on the lagging-strand template. Loss of nucleotide diphosphate kinase increases the cellular concentration of dCTP, which resulted in increased rates of mutations due to misinsertion of C opposite A and T. In an mmr ndk double mutant strain, these mutations were more frequent when the template A and T were on the leading strand, suggesting that lagging-strand synthesis was more error-prone, or less well corrected by proofreading, than was leading strand synthesis.
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Affiliation(s)
- Patricia L Foster
- Department of Biology, Indiana University, Bloomington, Indiana 47405
| | - Brittany A Niccum
- Department of Biology, Indiana University, Bloomington, Indiana 47405
| | - Ellen Popodi
- Department of Biology, Indiana University, Bloomington, Indiana 47405
| | - Jesse P Townes
- Department of Biology, Indiana University, Bloomington, Indiana 47405
| | - Heewook Lee
- School of Informatics, Computing, and Engineering, Indiana University, Bloomington, Indiana 47405
| | - Wazim MohammedIsmail
- School of Informatics, Computing, and Engineering, Indiana University, Bloomington, Indiana 47405
| | - Haixu Tang
- School of Informatics, Computing, and Engineering, Indiana University, Bloomington, Indiana 47405
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22
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Su KY, Goodman SD, Lai HM, Yen RS, Hu WY, Cheng WC, Lin LI, Yang YC, Fang WH. Proofreading and DNA Repair Assay Using Single Nucleotide Extension and MALDI-TOF Mass Spectrometry Analysis. J Vis Exp 2018:57862. [PMID: 29985320 PMCID: PMC6101880 DOI: 10.3791/57862] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The maintenance of the genome and its faithful replication is paramount for conserving genetic information. To assess high fidelity replication, we have developed a simple non-labeled and non-radio-isotopic method using a matrix-assisted laser desorption ionization with time-of-flight (MALDI-TOF) mass spectrometry (MS) analysis for a proofreading study. Here, a DNA polymerase [e.g., the Klenow fragment (KF) of Escherichia coli DNA polymerase I (pol I) in this study] in the presence of all four dideoxyribonucleotide triphosphates is used to process a mismatched primer-template duplex. The mismatched primer is then proofread/extended and subjected to MALDI-TOF MS. The products are distinguished by the mass change of the primer down to single nucleotide variations. Importantly, a proofreading can also be determined for internal single mismatches, albeit at different efficiencies. Mismatches located at 2-4-nucleotides (nt) from the 3' end were efficiently proofread by pol I, and a mismatch at 5 nt from the primer terminus showed only a partial correction. No proofreading occurred for internal mismatches located at 6 - 9 nt from the primer 3' end. This method can also be applied to DNA repair assays (e.g., assessing a base-lesion repair of substrates for the endo V repair pathway). Primers containing 3' penultimate deoxyinosine (dI) lesions could be corrected by pol I. Indeed, penultimate T-I, G-I, and A-I substrates had their last 2 dI-containing nucleotides excised by pol I before adding a correct ddN 5'-monophosphate (ddNMP) while penultimate C-I mismatches were tolerated by pol I, allowing the primer to be extended without repair, demonstrating the sensitivity and resolution of the MS assay to measure DNA repair.
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Affiliation(s)
- Kang-Yi Su
- Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University; Department of Laboratory Medicine, National Taiwan University Hospital
| | - Steven D Goodman
- Center for Microbial Pathogenesis, Nationwide Children's Hospital and the Department of Pediatrics, The Ohio State University
| | - Hung-Ming Lai
- Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University
| | - Rong-Syuan Yen
- Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University
| | - Wei-Yao Hu
- Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University
| | - Wern-Cherng Cheng
- Department of Laboratory Medicine, National Taiwan University Hospital
| | - Liang-In Lin
- Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University; Department of Laboratory Medicine, National Taiwan University Hospital
| | - Ya-Chien Yang
- Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University; Department of Laboratory Medicine, National Taiwan University Hospital
| | - Woei-Horng Fang
- Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University; Department of Laboratory Medicine, National Taiwan University Hospital;
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23
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Structural basis for overhang excision and terminal unwinding of DNA duplexes by TREX1. PLoS Biol 2018; 16:e2005653. [PMID: 29734329 PMCID: PMC5957452 DOI: 10.1371/journal.pbio.2005653] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 05/17/2018] [Accepted: 04/03/2018] [Indexed: 01/12/2023] Open
Abstract
Three prime repair exonuclease 1 (TREX1) is an essential exonuclease in mammalian cells, and numerous in vivo and in vitro data evidenced its participation in immunity regulation and in genotoxicity remediation. In these very complicated cellular functions, the molecular mechanisms by which duplex DNA substrates are processed are mostly elusive because of the lack of structure information. Here, we report multiple crystal structures of TREX1 complexed with various substrates to provide the structure basis for overhang excision and terminal unwinding of DNA duplexes. The substrates were designed to mimic the intermediate structural DNAs involved in various repair pathways. The results showed that the Leu24-Pro25-Ser26 cluster of TREX1 served to cap the nonscissile 5′-end of the DNA for precise removal of the short 3′-overhang in L- and Y-structural DNA or to wedge into the double-stranded region for further digestion along the duplex. Biochemical assays were also conducted to demonstrate that TREX1 can indeed degrade double-stranded DNA (dsDNA) to a full extent. Overall, this study provided unprecedented knowledge at the molecular level on the enzymatic substrate processing involved in prevention of immune activation and in responses to genotoxic stresses. For example, Arg128, whose mutation in TREX1 was linked to a disease state, were shown to exhibit consistent interaction patterns with the nonscissile strand in all of the structures we solved. Such structure basis is expected to play an indispensable role in elucidating the functional activities of TREX1 at the cellular level and in vivo. Three prime repair exonuclease 1 (TREX1) was shown to participate in various cellular events such as DNA repair, immunity regulation, and viral infection. In addition to relating to autoimmune diseases, this exonuclease also acts as a potential protein target for anticancer or antiviral therapies. A key for such broad attendance of TREX1 is the activities of precise trimming of the 3′-overhang in a double-stranded (dsDNA) and breaking of the terminal base pairing of the duplex. Here, we designed a series of structural DNA substrates and activity assays to delineate the underlying mechanisms. The structures newly resolved in this work indicated that the Leu24-Pro25-Ser26 cluster of TREX1 is essential for the enzyme to carry out the aforementioned activities. Together, our results established an integrated structure view into the versatile exonuclease functions of TREX1 and illuminated the molecular origin for the unique catalytic properties of TREX1 in processing various DNA intermediates in DNA repair and in cytosolic immunity regulation.
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24
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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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25
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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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26
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Shiraishi M, Ishino S, Cann I, Ishino Y. A functional endonuclease Q exists in the bacterial domain: identification and characterization of endonuclease Q from Bacillus pumilus. Biosci Biotechnol Biochem 2017; 81:931-937. [PMID: 28095753 DOI: 10.1080/09168451.2016.1277946] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
DNA base deamination occurs spontaneously under physiological conditions and is promoted by high temperature. Therefore, hyperthermophiles are expected to have efficient repair systems of the deaminated bases in their genomes. Endonuclease Q (EndoQ) was originally identified from the hyperthermophlic archaeon, Pyrococcus furiosus, as a hypoxanthine-specific endonuclease recently. Further biochemical analyses revealed that EndoQ also recognizes uracil, xanthine, and the AP site in DNA, and is probably involved in a specific repair process for damaged bases. Initial phylogenetic analysis showed that an EndoQ homolog is found only in the Thermococcales and some of the methanogens in Archaea, and is not present in most members of the domains Bacteria and Eukarya. A better understanding of the distribution of the EndoQ-mediated repair system is, therefore, of evolutionary interest. We showed here that an EndoQ-like polypeptide from Bacillus pumilus, belonging to the bacterial domain, is functional and has similar properties with the archaeal EndoQs.
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Affiliation(s)
- Miyako Shiraishi
- a Graduate School of Bioresource and Bioenvironmental Sciences , Kyushu University , Fukuoka , Japan.,d Institute for Universal Biology , University of Illinois at Urbana-Champaign , Urbana , IL , USA.,e Carl R. Woese Institute for Genomic Biology , University of Illinois at Urbana-Champaign , Urbana , IL , USA
| | - Sonoko Ishino
- a Graduate School of Bioresource and Bioenvironmental Sciences , Kyushu University , Fukuoka , Japan
| | - Isaac Cann
- b Department of Animal Science , University of Illinois at Urbana-Champaign , Urbana , IL , USA.,c Department of Microbiology , University of Illinois at Urbana-Champaign , Urbana , IL , USA.,d Institute for Universal Biology , University of Illinois at Urbana-Champaign , Urbana , IL , USA.,e Carl R. Woese Institute for Genomic Biology , University of Illinois at Urbana-Champaign , Urbana , IL , USA
| | - Yoshizumi Ishino
- a Graduate School of Bioresource and Bioenvironmental Sciences , Kyushu University , Fukuoka , Japan.,d Institute for Universal Biology , University of Illinois at Urbana-Champaign , Urbana , IL , USA.,e Carl R. Woese Institute for Genomic Biology , University of Illinois at Urbana-Champaign , Urbana , IL , USA
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27
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Feng H, Wang HY, Zhao HY. Novel Random Mutagenesis Method for Directed Evolution. Methods Mol Biol 2017; 1498:483-490. [PMID: 27709596 DOI: 10.1007/978-1-4939-6472-7_32] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Directed evolution is a powerful strategy for gene mutagenesis, and has been used for protein engineering both in scientific research and in the biotechnology industry. The routine method for directed evolution was developed by Stemmer in 1994 (Stemmer, Proc Natl Acad Sci USA 91, 10747-10751, 1994; Stemmer, Nature 370, 389-391, 1994). Since then, various methods have been introduced, each of which has advantages and limitations depending upon the targeted genes and procedure. In this chapter, a novel alternative directed evolution method which combines mutagenesis PCR with dITP and fragmentation by endonuclease V is described. The kanamycin resistance gene is used as a reporter gene to verify the novel method for directed evolution. This method for directed evolution has been demonstrated to be efficient, reproducible, and easy to manipulate in practice.
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Affiliation(s)
- Hong Feng
- The Key Laboratory for Bio-resources and Eco-Environment of Ministry of Education, The Sichuan Key Laboratory of Molecular Biology and Biotechnology, College of Life Sciences, Sichuan University, 29, Wangjiang Rd, Chengdu, 610064, Sichuan, China.
| | - Hai-Yan Wang
- The Key Laboratory for Bio-resources and Eco-Environment of Ministry of Education, The Sichuan Key Laboratory of Molecular Biology and Biotechnology, College of Life Sciences, Sichuan University, 29, Wangjiang Rd, Chengdu, 610064, Sichuan, China
| | - Hong-Yan Zhao
- The Key Laboratory for Bio-resources and Eco-Environment of Ministry of Education, The Sichuan Key Laboratory of Molecular Biology and Biotechnology, College of Life Sciences, Sichuan University, 29, Wangjiang Rd, Chengdu, 610064, Sichuan, China
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28
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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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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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Archaeal DNA Polymerase-B as a DNA Template Guardian: Links between Polymerases and Base/Alternative Excision Repair Enzymes in Handling the Deaminated Bases Uracil and Hypoxanthine. ARCHAEA-AN INTERNATIONAL MICROBIOLOGICAL JOURNAL 2016; 2016:1510938. [PMID: 27721668 PMCID: PMC5045986 DOI: 10.1155/2016/1510938] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 08/01/2016] [Indexed: 02/03/2023]
Abstract
In Archaea repair of uracil and hypoxanthine, which arise by deamination of cytosine and adenine, respectively, is initiated by three enzymes: Uracil-DNA-glycosylase (UDG, which recognises uracil); Endonuclease V (EndoV, which recognises hypoxanthine); and Endonuclease Q (EndoQ), (which recognises both uracil and hypoxanthine). Two archaeal DNA polymerases, Pol-B and Pol-D, are inhibited by deaminated bases in template strands, a feature unique to this domain. Thus the three repair enzymes and the two polymerases show overlapping specificity for uracil and hypoxanthine. Here it is demonstrated that binding of Pol-D to primer-templates containing deaminated bases inhibits the activity of UDG, EndoV, and EndoQ. Similarly Pol-B almost completely turns off EndoQ, extending earlier work that demonstrated that Pol-B reduces catalysis by UDG and EndoV. Pol-B was observed to be a more potent inhibitor of the enzymes compared to Pol-D. Although Pol-D is directly inhibited by template strand uracil, the presence of Pol-B further suppresses any residual activity of Pol-D, to near-zero levels. The results are compatible with Pol-D acting as the replicative polymerase and Pol-B functioning primarily as a guardian preventing deaminated base-induced DNA mutations.
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Bauer NC, Corbett AH, Doetsch PW. The current state of eukaryotic DNA base damage and repair. Nucleic Acids Res 2015; 43:10083-101. [PMID: 26519467 PMCID: PMC4666366 DOI: 10.1093/nar/gkv1136] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 10/16/2015] [Indexed: 12/15/2022] Open
Abstract
DNA damage is a natural hazard of life. The most common DNA lesions are base, sugar, and single-strand break damage resulting from oxidation, alkylation, deamination, and spontaneous hydrolysis. If left unrepaired, such lesions can become fixed in the genome as permanent mutations. Thus, evolution has led to the creation of several highly conserved, partially redundant pathways to repair or mitigate the effects of DNA base damage. The biochemical mechanisms of these pathways have been well characterized and the impact of this work was recently highlighted by the selection of Tomas Lindahl, Aziz Sancar and Paul Modrich as the recipients of the 2015 Nobel Prize in Chemistry for their seminal work in defining DNA repair pathways. However, how these repair pathways are regulated and interconnected is still being elucidated. This review focuses on the classical base excision repair and strand incision pathways in eukaryotes, considering both Saccharomyces cerevisiae and humans, and extends to some important questions and challenges facing the field of DNA base damage repair.
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Affiliation(s)
- Nicholas C Bauer
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA Graduate Program in Biochemistry, Cell, and Developmental Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Anita H Corbett
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Paul W Doetsch
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA 30322, USA Department of Radiation Oncology, Emory University School of Medicine, Atlanta, GA 30322, USA Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA 30322, USA
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Determinants of spontaneous mutation in the bacterium Escherichia coli as revealed by whole-genome sequencing. Proc Natl Acad Sci U S A 2015; 112:E5990-9. [PMID: 26460006 DOI: 10.1073/pnas.1512136112] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
A complete understanding of evolutionary processes requires that factors determining spontaneous mutation rates and spectra be identified and characterized. Using mutation accumulation followed by whole-genome sequencing, we found that the mutation rates of three widely diverged commensal Escherichia coli strains differ only by about 50%, suggesting that a rate of 1-2 × 10(-3) mutations per generation per genome is common for this bacterium. Four major forces are postulated to contribute to spontaneous mutations: intrinsic DNA polymerase errors, endogenously induced DNA damage, DNA damage caused by exogenous agents, and the activities of error-prone polymerases. To determine the relative importance of these factors, we studied 11 strains, each defective for a major DNA repair pathway. The striking result was that only loss of the ability to prevent or repair oxidative DNA damage significantly impacted mutation rates or spectra. These results suggest that, with the exception of oxidative damage, endogenously induced DNA damage does not perturb the overall accuracy of DNA replication in normally growing cells and that repair pathways may exist primarily to defend against exogenously induced DNA damage. The thousands of mutations caused by oxidative damage recovered across the entire genome revealed strong local-sequence biases of these mutations. Specifically, we found that the identity of the 3' base can affect the mutability of a purine by oxidative damage by as much as eightfold.
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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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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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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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Costa SB, Campos ACC, Pereira ACM, de Mattos-Guaraldi AL, Júnior RH, Rosa ACP, Asad LMBO. Adherence to abiotic surface induces SOS response in Escherichia coli K-12 strains under aerobic and anaerobic conditions. MICROBIOLOGY-SGM 2014; 160:1964-1973. [PMID: 25012969 DOI: 10.1099/mic.0.075317-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
During the colonization of surfaces, Escherichia coli bacteria often encounter DNA-damaging agents and these agents can induce several defence mechanisms. Base excision repair (BER) is dedicated to the repair of oxidative DNA damage caused by reactive oxygen species (ROS) generated by chemical and physical agents or by metabolism. In this work, we have evaluated whether the interaction with an abiotic surface by mutants derived from E. coli K-12 deficient in some enzymes that are part of BER causes DNA damage and associated filamentation. Moreover, we studied the role of endonuclease V (nfi gene; 1506 mutant strain) in biofilm formation. Endonuclease V is an enzyme that is involved in DNA repair of nitrosative lesions. We verified that endonuclease V is involved in biofilm formation. Our results showed more filamentation in the xthA mutant (BW9091) and triple xthA nfo nth mutant (BW535) than in the wild-type strain (AB1157). By contrast, the mutant nfi did not present filamentation in biofilm, although its wild-type strain (1466) showed rare filaments in biofilm. The filamentation of bacterial cells attaching to a surface was a consequence of SOS induction measured by the SOS chromotest. However, biofilm formation depended on the ability of the bacteria to induce the SOS response since the mutant lexA Ind(-) did not induce the SOS response and did not form any biofilm. Oxygen tension was an important factor for the interaction of the BER mutants, since these mutants exhibited decreased quantitative adherence under anaerobic conditions. However, our results showed that the presence or absence of oxygen did not affect the viability of BW9091 and BW535 strains. The nfi mutant and its wild-type did not exhibit decreased biofilm formation under anaerobic conditions. Scanning electron microscopy was also performed on the E. coli K-12 strains that had adhered to the glass, and we observed the presence of a structure similar to an extracellular matrix that depended on the oxygen tension. In conclusion, it was proven that bacterial interaction with abiotic surfaces can lead to SOS induction and associated filamentation. Moreover, we verified that endonuclease V is involved in biofilm formation.
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Affiliation(s)
- Suelen B Costa
- Departamento de Microbiologia, Imunologia e Parasitologia, Faculdade de Ciências Médicas, Universidade do Estado do Rio de Janeiro, Brazil
| | - Ana Carolina C Campos
- Departamento de Microbiologia, Imunologia e Parasitologia, Faculdade de Ciências Médicas, Universidade do Estado do Rio de Janeiro, Brazil
| | - Ana Claudia M Pereira
- Departamento de Microbiologia, Imunologia e Parasitologia, Faculdade de Ciências Médicas, Universidade do Estado do Rio de Janeiro, Brazil
| | - Ana Luiza de Mattos-Guaraldi
- Departamento de Microbiologia, Imunologia e Parasitologia, Faculdade de Ciências Médicas, Universidade do Estado do Rio de Janeiro, Brazil
| | - Raphael Hirata Júnior
- Departamento de Microbiologia, Imunologia e Parasitologia, Faculdade de Ciências Médicas, Universidade do Estado do Rio de Janeiro, Brazil
| | - Ana Cláudia P Rosa
- Departamento de Microbiologia, Imunologia e Parasitologia, Faculdade de Ciências Médicas, Universidade do Estado do Rio de Janeiro, Brazil
| | - Lídia M B O Asad
- Departamento de Biofísica e Biometria, Instituto de Biologia Roberto Alcântara Gomes, Universidade do Estado do Rio de Janeiro, Brazil
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Yan S, Sorrell M, Berman Z. Functional interplay between ATM/ATR-mediated DNA damage response and DNA repair pathways in oxidative stress. Cell Mol Life Sci 2014; 71:3951-67. [PMID: 24947324 DOI: 10.1007/s00018-014-1666-4] [Citation(s) in RCA: 158] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 06/03/2014] [Accepted: 06/05/2014] [Indexed: 02/07/2023]
Abstract
To maintain genome stability, cells have evolved various DNA repair pathways to deal with oxidative DNA damage. DNA damage response (DDR) pathways, including ATM-Chk2 and ATR-Chk1 checkpoints, are also activated in oxidative stress to coordinate DNA repair, cell cycle progression, transcription, apoptosis, and senescence. Several studies demonstrate that DDR pathways can regulate DNA repair pathways. On the other hand, accumulating evidence suggests that DNA repair pathways may modulate DDR pathway activation as well. In this review, we summarize our current understanding of how various DNA repair and DDR pathways are activated in response to oxidative DNA damage primarily from studies in eukaryotes. In particular, we analyze the functional interplay between DNA repair and DDR pathways in oxidative stress. A better understanding of cellular response to oxidative stress may provide novel avenues of treating human diseases, such as cancer and neurodegenerative disorders.
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Affiliation(s)
- Shan Yan
- Department of Biological Sciences, University of North Carolina at Charlotte, 9201 University City Blvd., Charlotte, NC, 28223, USA,
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41
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Hsiao YY, Fang WH, Lee CC, Chen YP, Yuan HS. Structural insights into DNA repair by RNase T--an exonuclease processing 3' end of structured DNA in repair pathways. PLoS Biol 2014; 12:e1001803. [PMID: 24594808 PMCID: PMC3942315 DOI: 10.1371/journal.pbio.1001803] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Accepted: 01/21/2014] [Indexed: 11/19/2022] Open
Abstract
DNA repair mechanisms are essential for preservation of genome integrity. However, it is not clear how DNA are selected and processed at broken ends by exonucleases during repair pathways. Here we show that the DnaQ-like exonuclease RNase T is critical for Escherichia coli resistance to various DNA-damaging agents and UV radiation. RNase T specifically trims the 3' end of structured DNA, including bulge, bubble, and Y-structured DNA, and it can work with Endonuclease V to restore the deaminated base in an inosine-containing heteroduplex DNA. Crystal structure analyses further reveal how RNase T recognizes the bulge DNA by inserting a phenylalanine into the bulge, and as a result the 3' end of blunt-end bulge DNA can be digested by RNase T. In contrast, the homodimeric RNase T interacts with the Y-structured DNA by a different binding mode via a single protomer so that the 3' overhang of the Y-structured DNA can be trimmed closely to the duplex region. Our data suggest that RNase T likely processes bulge and bubble DNA in the Endonuclease V-dependent DNA repair, whereas it processes Y-structured DNA in UV-induced and various other DNA repair pathways. This study thus provides mechanistic insights for RNase T and thousands of DnaQ-like exonucleases in DNA 3'-end processing.
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Affiliation(s)
- Yu-Yuan Hsiao
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, Republic of China
- Department of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan, Republic of China
| | - Woei-Horng Fang
- Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei, Taiwan, Republic of China
| | - Chia-Chia Lee
- Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei, Taiwan, Republic of China
| | - Yi-Ping Chen
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, Republic of China
| | - Hanna S. Yuan
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, Republic of China
- Graduate Institute of Biochemistry and Molecular Biology, National Taiwan University, Taipei, Taiwan, Republic of China
- * E-mail:
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42
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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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Tee KL, Wong TS. Polishing the craft of genetic diversity creation in directed evolution. Biotechnol Adv 2013; 31:1707-21. [PMID: 24012599 DOI: 10.1016/j.biotechadv.2013.08.021] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 08/31/2013] [Accepted: 08/31/2013] [Indexed: 12/25/2022]
Abstract
Genetic diversity creation is a core technology in directed evolution where a high quality mutant library is crucial to its success. Owing to its importance, the technology in genetic diversity creation has seen rapid development over the years and its application has diversified into other fields of scientific research. The advances in molecular cloning and mutagenesis since 2008 were reviewed. Specifically, new cloning techniques were classified based on their principles of complementary overhangs, homologous sequences, overlapping PCR and megaprimers and the advantages, drawbacks and performances of these methods were highlighted. New mutagenesis methods developed for random mutagenesis, focused mutagenesis and DNA recombination were surveyed. The technical requirements of these methods and the mutational spectra were compared and discussed with references to commonly used techniques. The trends of mutant library preparation were summarised. Challenges in genetic diversity creation were discussed with emphases on creating "smart" libraries, controlling the mutagenesis spectrum and specific challenges in each group of mutagenesis methods. An outline of the wider applications of genetic diversity creation includes genome engineering, viral evolution, metagenomics and a study of protein functions. The review ends with an outlook for genetic diversity creation and the prospective developments that can have future impact in this field.
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Affiliation(s)
- Kang Lan Tee
- Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester M1 7DN, England, United Kingdom
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44
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Lee CC, Yang YC, Goodman SD, Lin CJ, Chen YA, Wang YT, Cheng WC, Lin LI, Fang WH. The excision of 3' penultimate errors by DNA polymerase I and its role in endonuclease V-mediated DNA repair. DNA Repair (Amst) 2013; 12:899-911. [PMID: 24012058 DOI: 10.1016/j.dnarep.2013.08.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 08/12/2013] [Accepted: 08/13/2013] [Indexed: 11/28/2022]
Abstract
Deamination of adenine can occur spontaneously under physiological conditions, and is enhanced by exposure of DNA to ionizing radiation, UV light, nitrous acid, or heat, generating the highly mutagenic lesion of deoxyinosine in DNA. Such DNA lesions tends to generate A:T to G:C transition mutations if unrepaired. In Escherichia coli, deoxyinosine is primarily removed through a repair pathway initiated by endonuclease V (endo V). In this study, we compared the repair of three mutagenic deoxyinosine lesions of A-I, G-I, and T-I using E. coli cell-free extracts as well as reconstituted protein system. We found that 3'-5' exonuclease activity of DNA polymerase I (pol I) was very important for processing all deoxyinosine lesions. To understand the nature of pol I in removing damaged nucleotides, we systemically analyzed its proofreading to 12 possible mismatches 3'-penultimate of a nick, a configuration that represents a repair intermediate generated by endo V. The results showed all mismatches as well as deoxyinosine at the 3' penultimate site were corrected with similar efficiency. This study strongly supports for the idea that the 3'-5' exonuclease activity of E. coli pol I is the primary exonuclease activity for removing 3'-penultimate deoxyinosines derived from endo V nicking reaction.
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Affiliation(s)
- Chia-Chia Lee
- Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei, 100-02, Taiwan, ROC
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45
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Simone PD, Pavlov YI, Borgstahl GEO. ITPA (inosine triphosphate pyrophosphatase): from surveillance of nucleotide pools to human disease and pharmacogenetics. Mutat Res 2013; 753:131-146. [PMID: 23969025 DOI: 10.1016/j.mrrev.2013.08.001] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 07/31/2013] [Accepted: 08/02/2013] [Indexed: 01/08/2023]
Abstract
Cellular nucleotide pools are often contaminated by base analog nucleotides which interfere with a plethora of biological reactions, from DNA and RNA synthesis to cellular signaling. An evolutionarily conserved inosine triphosphate pyrophosphatase (ITPA) removes the non-canonical purine (d)NTPs inosine triphosphate and xanthosine triphosphate by hydrolyzing them into their monophosphate form and pyrophosphate. Mutations in the ITPA orthologs in model organisms lead to genetic instability and, in mice, to severe developmental anomalies. In humans there is genetic polymorphism in ITPA. One allele leads to a proline to threonine substitution at amino acid 32 and causes varying degrees of ITPA deficiency in tissues and plays a role in patients' response to drugs. Structural analysis of this mutant protein reveals that the protein is destabilized by the formation of a cavity in its hydrophobic core. The Pro32Thr allele is thought to cause the observed dominant negative effect because the resulting active enzyme monomer targets both homo- and heterodimers to degradation.
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Affiliation(s)
- Peter D Simone
- The Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Youri I Pavlov
- The Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198, USA; Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, USA; Department of Pathology and Microbiology, University of Nebraska Medical Center, USA; Department of Genetics, St-Petersburg University, St-Petersburg, 199034, Russia
| | - Gloria E O Borgstahl
- The Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198, USA; Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, USA; Department of Pharmaceutical Sciences, University of Nebraska Medical Center, USA.
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