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Ding Y, Liu Q. Targeting the nucleic acid oxidative damage repair enzyme MTH1: a promising therapeutic option. Front Cell Dev Biol 2024; 12:1334417. [PMID: 38357002 PMCID: PMC10864502 DOI: 10.3389/fcell.2024.1334417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 01/17/2024] [Indexed: 02/16/2024] Open
Abstract
The accumulation of reactive oxygen species (ROS) plays a pivotal role in the development of various diseases, including cancer. Elevated ROS levels cause oxidative stress, resulting in detrimental effects on organisms and enabling tumors to develop adaptive responses. Targeting these enhanced oxidative stress protection mechanisms could offer therapeutic benefits with high specificity, as normal cells exhibit lower dependency on these pathways. MTH1 (mutT homolog 1), a homolog of Escherichia coli's MutT, is crucial in this context. It sanitizes the nucleotide pool, preventing incorporation of oxidized nucleotides, thus safeguarding DNA integrity. This study explores MTH1's potential as a therapeutic target, particularly in cancer treatment, providing insights into its structure, function, and role in disease progression.
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Affiliation(s)
| | - Qingquan Liu
- Department of Hepatobiliary Surgery, The First Affiliated Hospital of Gannan Medical University, Jiangxi, China
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2
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Li C, Xue Y, Ba X, Wang R. The Role of 8-oxoG Repair Systems in Tumorigenesis and Cancer Therapy. Cells 2022; 11:cells11233798. [PMID: 36497058 PMCID: PMC9735852 DOI: 10.3390/cells11233798] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 11/09/2022] [Accepted: 11/25/2022] [Indexed: 11/29/2022] Open
Abstract
Tumorigenesis is highly correlated with the accumulation of mutations. The abundant and extensive DNA oxidation product, 8-Oxoguanine (8-oxoG), can cause mutations if it is not repaired by 8-oxoG repair systems. Therefore, the accumulation of 8-oxoG plays an essential role in tumorigenesis. To avoid the accumulation of 8-oxoG in the genome, base excision repair (BER), initiated by 8-oxoguanine DNA glycosylase1 (OGG1), is responsible for the removal of genomic 8-oxoG. It has been proven that 8-oxoG levels are significantly elevated in cancer cells compared with cells of normal tissues, and the induction of DNA damage by some antitumor drugs involves direct or indirect interference with BER, especially through inducing the production and accumulation of reactive oxygen species (ROS), which can lead to tumor cell death. In addition, the absence of the core components of BER can result in embryonic or early post-natal lethality in mice. Therefore, targeting 8-oxoG repair systems with inhibitors is a promising avenue for tumor therapy. In this study, we summarize the impact of 8-oxoG accumulation on tumorigenesis and the current status of cancer therapy approaches exploiting 8-oxoG repair enzyme targeting, as well as possible synergistic lethality strategies involving exogenous ROS-inducing agents.
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Affiliation(s)
- Chunshuang Li
- Center for Cell Structure and Function, Key Laboratory of Animal Resistance Biology of Shandong Province, College of Life Sciences, Shandong Normal University, Jinan 250014, China
- The Key Laboratory of Molecular Epigenetics of Education, School of Life Science, Northeast Normal University, Changchun 130024, China
| | - Yaoyao Xue
- The Key Laboratory of Molecular Epigenetics of Education, School of Life Science, Northeast Normal University, Changchun 130024, China
| | - Xueqing Ba
- The Key Laboratory of Molecular Epigenetics of Education, School of Life Science, Northeast Normal University, Changchun 130024, China
- Correspondence: (X.B.); (R.W.)
| | - Ruoxi Wang
- Center for Cell Structure and Function, Key Laboratory of Animal Resistance Biology of Shandong Province, College of Life Sciences, Shandong Normal University, Jinan 250014, China
- Correspondence: (X.B.); (R.W.)
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3
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Wahi D, Soni D, Grover A. A Double-Edged Sword: The Anti-Cancer Effects of Emodin by Inhibiting the Redox-Protective Protein MTH1 and Augmenting ROS in NSCLC. J Cancer 2021; 12:652-681. [PMID: 33403025 PMCID: PMC7778552 DOI: 10.7150/jca.41160] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 04/01/2020] [Indexed: 12/23/2022] Open
Abstract
Background: Reactive oxygen species (ROS), playing a two-fold role in tumorigenesis, are responsible for tumor formation and progression through the induction of genome instability and pro-oncogenic signaling. The same ROS is toxic to cancer cells at higher levels, oxidizing free nucleotide precursors (dNTPs) as well as damaging DNA leading to cell senescence. Research has highlighted the tumor cell-specific expression of a redox-protective phosphatase, MutT homolog 1 (MTH1), that performs the enzymatic conversion of oxidized nucleotides (like 8-oxo-dGTP) to their corresponding monophosphates, up-regulated in numerous cancers, circumventing their misincorporation into the genomic DNA and preventing damage and cell death. Methods: To identify novel natural small molecular inhibitors of MTH1 to be used as cancer therapeutic agents, molecular screening for MTH1 active site binders was performed from natural small molecular libraries. Emodin was identified as a lead compound for MTH1 active site functional inhibition and its action on MTH1 inhibition was validated on non-small cell lung cancer cellular models (NSCLC). Results: Our study provides strong evidence that emodin mediated MTH1 inhibition impaired NSCLC cell growth, inducing senescence. Emodin treatment enhanced the cellular ROS burdens, on one hand, damaged dNTP pools and inhibited MTH1 function on the other. Our work on emodin indicates that ROS is the key driver of cancer cell-specific increased DNA damage and apoptosis upon MTH1 inhibition. Consequently, we observed a time-dependent increase in NSCL cancer cell susceptibility to oxidative stress with emodin treatment. Conclusions: Based on our data, the anti-cancer effects of emodin as an MTH1 inhibitor have clinical potential as a single agent capable of functioning as a ROS inducer and simultaneous blocker of dNTP pool sanitation in the treatment of NSCL cancers. Collectively, our results have identified for the first time that the potential molecular mechanism of emodin function, increasing DNA damage and apoptosis in cancer cells, is via MTH1 inhibition.
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Affiliation(s)
- Divya Wahi
- School of Biotechnology, Jawaharlal Nehru University, New Delhi, India - 110067
| | - Deepika Soni
- School of Biotechnology, Jawaharlal Nehru University, New Delhi, India - 110067
| | - Abhinav Grover
- School of Biotechnology, Jawaharlal Nehru University, New Delhi, India - 110067
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Yin Y, Chen F. Targeting human MutT homolog 1 (MTH1) for cancer eradication: current progress and perspectives. Acta Pharm Sin B 2020; 10:2259-2271. [PMID: 33354500 PMCID: PMC7745060 DOI: 10.1016/j.apsb.2020.02.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 02/11/2020] [Accepted: 02/21/2020] [Indexed: 01/20/2023] Open
Abstract
Since accelerated metabolism produces much higher levels of reactive oxygen species (ROS) in cancer cells compared to ROS levels found in normal cells, human MutT homolog 1 (MTH1), which sanitizes oxidized nucleotide pools, was recently demonstrated to be crucial for the survival of cancer cells, but not required for the proliferation of normal cells. Therefore, dozens of MTH1 inhibitors have been developed with the aim of suppressing cancer growth by accumulating oxidative damage in cancer cells. While several inhibitors were indeed confirmed to be effective, some inhibitors failed to kill cancer cells, complicating MTH1 as a viable target for cancer eradication. In this review, we summarize the current status of developing MTH1 inhibitors as drug candidates, classify the MTH1 inhibitors based on their structures, and offer our perspectives toward the therapeutic potential against cancer through the targeting of MTH1.
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Key Words
- AI, 7-azaindole
- AID, 7-azaindazole
- AP, aminopyrimidine
- AQ, amidoquinolines
- AZ, 2-aminoquinazoline
- Anticancer
- CETSA, cellular thermal shift assay
- CR, cyclometalated ruthenium
- DDR, DNA damage response
- DNA repair
- F, fragment
- FP, farnesyl phenolic
- IC50, half-maximal inhibitory concentrations
- Inhibitor
- MMR, DNA mismatch repair
- MTH1
- MTH1, human MutT homolog 1
- NSCLC, non-small cell lung cancer
- Oxidized nucleotide
- P, purinone
- PDT, photodynamic therapy
- PM, purinone macrocycle
- Pu, purine
- ROS, reactive oxygen species
- TLR7, Toll-like receptor 7
- TPP, thermal proteome profiling
- TS-FITGE, thermal stability shift-based fluorescence difference in two-dimensional gel electrophoresis
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Affiliation(s)
- Yizhen Yin
- Institute of Pharmaceutical Science and Technology, Zhejiang University of Technology, Hangzhou 310014, China
| | - Fener Chen
- Institute of Pharmaceutical Science and Technology, Zhejiang University of Technology, Hangzhou 310014, China
- Engineering Center of Catalysis and Synthesis for Chiral Molecules, Department of Chemistry, Fudan University, Shanghai 200433, China
- Shanghai Engineering Center of Industrial Asymmetric Catalysis for Chiral Drugs, Shanghai 200433, China
- Corresponding author. Tel./fax: +86 21 65643811.
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Raj P, Karthik S, Arif SM, Varshney U, Vijayan M. Plasticity, ligand conformation and enzyme action of Mycobacterium smegmatis MutT1. Acta Crystallogr D Struct Biol 2020; 76:982-992. [PMID: 33021500 DOI: 10.1107/s2059798320010992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 08/11/2020] [Indexed: 11/10/2022] Open
Abstract
Mycobacterium smegmatis MutT1 (MsMutT1) is a sanitation enzyme made up of an N-terminal Nudix hydrolase domain and a C-terminal domain resembling a histidine phosphatase. It has been established that the action of MutT1 on 8-oxo-dGTP, 8-oxo-GTP and diadenosine polyphosphates is modulated by intermolecular interactions. In order to further explore this and to elucidate the structural basis of its differential action on 8-oxo-NTPs and unsubstituted NTPs, the crystal structures of complexes of MsMutT1 with 8-oxo-dGTP, GMPPNP and GMPPCP have been determined. Replacement soaking was used in order to ensure that the complexes were isomorphous to one another. Analysis of the structural data led to the elucidation of a relationship between the arrangements of molecules observed in the crystals, molecular plasticity and the action of the enzyme on nucleotides. The dominant mode of arrangement involving a head-to-tail sequence predominantly leads to the generation of NDPs. The other mode of packing arrangement appears to preferentially generate NMPs. This work also provides interesting insights into the dependence of enzyme action on the conformation of the ligand. The possibility of modulating the enzyme action through differences in intermolecular interactions and ligand conformations makes MsMutT1 a versatile enzyme.
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Affiliation(s)
- Prateek Raj
- Molecular Biophysics Unit, Indian Institute of Science, Bengaluru 560 012, India
| | - S Karthik
- Molecular Biophysics Unit, Indian Institute of Science, Bengaluru 560 012, India
| | - S M Arif
- Molecular Biophysics Unit, Indian Institute of Science, Bengaluru 560 012, India
| | - U Varshney
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru 560 012, India
| | - M Vijayan
- Molecular Biophysics Unit, Indian Institute of Science, Bengaluru 560 012, India
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Boguszewska K, Szewczuk M, Kaźmierczak-Barańska J, Karwowski BT. The Similarities between Human Mitochondria and Bacteria in the Context of Structure, Genome, and Base Excision Repair System. Molecules 2020; 25:E2857. [PMID: 32575813 PMCID: PMC7356350 DOI: 10.3390/molecules25122857] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 06/17/2020] [Accepted: 06/19/2020] [Indexed: 02/06/2023] Open
Abstract
Mitochondria emerged from bacterial ancestors during endosymbiosis and are crucial for cellular processes such as energy production and homeostasis, stress responses, cell survival, and more. They are the site of aerobic respiration and adenosine triphosphate (ATP) production in eukaryotes. However, oxidative phosphorylation (OXPHOS) is also the source of reactive oxygen species (ROS), which are both important and dangerous for the cell. Human mitochondria contain mitochondrial DNA (mtDNA), and its integrity may be endangered by the action of ROS. Fortunately, human mitochondria have repair mechanisms that allow protecting mtDNA and repairing lesions that may contribute to the occurrence of mutations. Mutagenesis of the mitochondrial genome may manifest in the form of pathological states such as mitochondrial, neurodegenerative, and/or cardiovascular diseases, premature aging, and cancer. The review describes the mitochondrial structure, genome, and the main mitochondrial repair mechanism (base excision repair (BER)) of oxidative lesions in the context of common features between human mitochondria and bacteria. The authors present a holistic view of the similarities of mitochondria and bacteria to show that bacteria may be an interesting experimental model for studying mitochondrial diseases, especially those where the mechanism of DNA repair is impaired.
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Affiliation(s)
| | | | | | - Bolesław T. Karwowski
- DNA Damage Laboratory of Food Science Department, Faculty of Pharmacy, Medical University of Lodz, ul. Muszynskiego 1, 90-151 Lodz, Poland; (K.B.); (M.S.); (J.K.-B.)
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Jemth AS, Scaletti E, Carter M, Helleday T, Stenmark P. Crystal Structure and Substrate Specificity of the 8-oxo-dGTP Hydrolase NUDT1 from Arabidopsis thaliana. Biochemistry 2019; 58:887-899. [PMID: 30614695 DOI: 10.1021/acs.biochem.8b00950] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Arabidopsis thaliana NUDT1 (AtNUDT1) belongs to the Nudix family of proteins, which have a diverse range of substrates, including oxidized nucleotides such as 8-oxo-dGTP. The hydrolysis of oxidized dNTPs is highly important as it prevents their incorporation into DNA, thus preventing mutations and DNA damage. AtNUDT1 is the sole Nudix enzyme from A. thaliana shown to have activity against 8-oxo-dGTP. We present the structure of AtNUDT1 in complex with 8-oxo-dGTP. Structural comparison with bacterial and human homologues reveals a conserved overall fold. Analysis of the 8-oxo-dGTP binding mode shows that the residues Asn76 and Ser89 interact with the O8 atom of the substrate, a feature not observed in structures of protein homologues solved to date. Kinetic analysis of wild-type and mutant AtNUDT1 confirmed that these active site residues influence 8-oxo-dGTP hydrolysis. A recent study showed that AtNUDT1 is also able to hydrolyze terpene compounds. The diversity of reactions catalyzed by AtNUDT1 suggests that this Nudix enzyme from higher plants has evolved in a manner distinct to those from other organisms.
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Affiliation(s)
- Ann-Sofie Jemth
- Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics , Karolinska Institutet , Stockholm S-171 21 , Sweden
| | - Emma Scaletti
- Department of Biochemistry and Biophysics , Stockholm University , Stockholm S-106 91 , Sweden
| | - Megan Carter
- Department of Biochemistry and Biophysics , Stockholm University , Stockholm S-106 91 , Sweden
| | - Thomas Helleday
- Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics , Karolinska Institutet , Stockholm S-171 21 , Sweden.,Sheffield Cancer Centre, Department of Oncology and Metabolism , University of Sheffield , Sheffield S10 2RX , United Kingdom
| | - Pål Stenmark
- Department of Biochemistry and Biophysics , Stockholm University , Stockholm S-106 91 , Sweden.,Department of Experimental Medical Science , Lund University , Lund 221 00 , Sweden
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Pompsch M, Vogel J, Classen F, Kranz P, Iliakis G, Riffkin H, Brockmeier U, Metzen E. The presumed MTH1-inhibitor TH588 sensitizes colorectal carcinoma cells to ionizing radiation in hypoxia. BMC Cancer 2018; 18:1190. [PMID: 30497423 PMCID: PMC6267833 DOI: 10.1186/s12885-018-5095-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 11/15/2018] [Indexed: 12/13/2022] Open
Abstract
Background The nudix family member enzyme MutT homologue-1 (MTH1) hydrolyses the oxidized nucleotides 8-oxo-dGTP and 2-hydroxy-dATP and thus prevents the incorporation of damaged nucleotides into nuclear and mitochondrial DNA. Therefore MTH1 was proposed to protect cancer cells from oxidative DNA lesions and subsequent cell death. We investigated whether the bona fide MTH1 inhibitor TH588 affects responses of cultured colorectal tumor cells to ionizing radiation (IR) in normoxia and in moderate or severe hypoxia. Methods TH588 was tested in cell viability and survival assays (tetrazolium dye (MTT), propidium iodide staining, caspase-3 activity, and colony formation assays (CFA)) in colorectal carcinoma cells (HCT116 and SW480) in combination with IR in normoxia and in hypoxia. Additionally, MTH1 was targeted by lentiviral shRNA expression. Human umbilical vein endothelial cells (HUVEC) were assessed in MTT assays. Results In all cell lines tested, TH588 dose-dependently impaired cell survival. In CFAs, TH588 and IR effects on carcinoma cells were additive in normoxia and in hypoxia. Using 3 different shRNAs, the lentiviral approach was detrimental to SW480, but not to HCT116. Conclusions TH588 has cytotoxic effects on transformed and untransformed cells and synergizes with IR in normoxia and in hypoxia. TH588 toxicity is not fully explained by MTH1 inhibition as HCT116 were unaffected by lentiviral suppression of MTH1 expression. TH588 should be explored further because it has radiosensitizing effects in hypoxia.
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Affiliation(s)
- Mosche Pompsch
- Institut für Physiologie, Universität Duisburg-Essen, Hufelandstraße 55, D45122, Essen, Germany
| | - Julia Vogel
- Institut für Physiologie, Universität Duisburg-Essen, Hufelandstraße 55, D45122, Essen, Germany
| | - Fabian Classen
- Institut für Physiologie, Universität Duisburg-Essen, Hufelandstraße 55, D45122, Essen, Germany
| | - Philip Kranz
- Institut für Physiologie, Universität Duisburg-Essen, Hufelandstraße 55, D45122, Essen, Germany
| | - George Iliakis
- Institut für Medizinische Strahlenbiologie, Universität Duisburg-Essen, Hufelandstraße 55, D45122, Essen, Germany
| | - Helena Riffkin
- Institut für Physiologie, Universität Duisburg-Essen, Hufelandstraße 55, D45122, Essen, Germany
| | - Ulf Brockmeier
- Institut für Physiologie, Universität Duisburg-Essen, Hufelandstraße 55, D45122, Essen, Germany
| | - Eric Metzen
- Institut für Physiologie, Universität Duisburg-Essen, Hufelandstraße 55, D45122, Essen, Germany.
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9
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Singh A, Mohammad Arif S, Biak Sang P, Varshney U, Vijayan M. Structural insights into the specificity and catalytic mechanism of mycobacterial nucleotide pool sanitizing enzyme MutT2. J Struct Biol 2018; 204:449-456. [PMID: 30312643 DOI: 10.1016/j.jsb.2018.10.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 10/04/2018] [Accepted: 10/07/2018] [Indexed: 12/29/2022]
Abstract
Mis-incorporation of modified nucleotides, such as 5-methyl-dCTP or 8-oxo-dGTP, in DNA can be detrimental to genomic integrity. MutT proteins are sanitization enzymes which function by hydrolyzing such nucleotides and regulating the pool of free nucleotides in the cytoplasm. Mycobacterial genomes have a set of four MutT homologs, namely, MutT1, MutT2, MutT3 and MutT4. Mycobacterial MutT2 hydrolyzes 5 m-dCTP and 8-oxo-dGTP to their respective monophosphate products. Additionally, it can hydrolyze canonical nucleotides dCTP and CTP, with a suggested role in sustaining their optimal levels in the nucleotide pool. The structures of M. smegmatis MutT2 and its complexes with cytosine derivatives have been determined at resolutions ranging from 1.10 Å to 1.73 Å. The apo enzyme and its complexes with products (dCMP, CMP and 5 m-dCMP) crystallize in space group P21212, while those involving substrates (dCTP, CTP and 5 m-dCTP) crystallize in space group P21. The molecule takes an α/β/α sandwich fold arrangement, as observed in other MutT homologs. The nucleoside moiety of the ligands is similarly located in all the complexes, while the location of the remaining tail exhibits variability. This is the first report of a MutT2-type protein in complex with ligands. A critical interaction involving Asp116 confers the specificity of the enzyme towards cytosine moieties. A conserved set of enzyme-ligand interactions along with concerted movements of important water molecules provide insights into the mechanism of action.
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Affiliation(s)
- Amandeep Singh
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
| | | | - Pau Biak Sang
- Dept. of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India
| | - Umesh Varshney
- Dept. of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India
| | - M Vijayan
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India.
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Niu RJ, Zheng QC, Zhang HX. The influence of residue in the position of 116 on the inhibitory potency of TH588 for MTH1. J Mol Graph Model 2018; 85:75-83. [PMID: 30103119 DOI: 10.1016/j.jmgm.2018.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 07/23/2018] [Accepted: 08/03/2018] [Indexed: 11/29/2022]
Abstract
As one of the first-in-class inhibitor, TH588 was found to be efficient in the suppression of MutT homolog1 (MTH1). A recent work shows that the inhibitory potency of TH588 against human MTH1 (hsMTH1) is approximately 20-fold over that of mouse MTH1 (mmMTH1) and identifies residue in position 116 in MTH1 has an important contribution to TH588 affinity. But the effect of residue Leu or Met in position 116 on the binding affinity remains unclear. In this study, molecular dynamics (MD) simulations and free energy calculations were used to elucidate the mechanism about the effect of residue 116 to the different inhibitory potency of TH588 against MTH1. The binding free energy of TH588 in M116 complexes predicated by the Molecular Mechanics/Generalized Born Surface Area (MM/GBSA) is much lower than that in L116 complexes, which is consistent with the experiment results. The analysis of the individual energy terms suggests that the non-polar interactions are important for distinguishing the binding of TH588. The MD results show that the Leu116 disrupts the interactions between Asn33 and TH588, thus induces the conformational changes of Asn33 as well as TH588. The altered interactions between TH588 and mmMTH1 change the flexibility of TH588, which could induce the remarkable conformational fluctuation of mmMTH1. The conformations of the two loops covering the binding pocket have obvious influence on the opening or closure of the active site. The more open binding site may explain the lower inhibitor potency of TH588 against mmMTH1 than hsMTH1. Our results provide mechanistic insight into the effect of different residue Leu or Met in position 116 on the binding affinity of TH588 for MTH1, which is expected to contribute to the further rational design of more potent inhibitors.
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Affiliation(s)
- Rui-Juan Niu
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun, 130023, PR China
| | - Qing-Chuan Zheng
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun, 130023, PR China; Key Laboratory for Molecular Enzymology and Engineering of the Ministry of Education, Jilin University, Changchun, 130023, PR China.
| | - Hong-Xing Zhang
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun, 130023, PR China.
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Lu Y, Zhou X, Zeng Q, Liu D, Yue C. Differential expression profile analysis of DNA damage repair genes in CD133 +/CD133 - colorectal cancer cells. Oncol Lett 2017; 14:2359-2368. [PMID: 28789452 DOI: 10.3892/ol.2017.6415] [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: 07/20/2015] [Accepted: 01/06/2017] [Indexed: 11/06/2022] Open
Abstract
The present study examined differential expression levels of DNA damage repair genes in COLO 205 colorectal cancer cells, with the aim of identifying novel biomarkers for the molecular diagnosis and treatment of colorectal cancer. COLO 205-derived cell spheres were cultured in serum-free medium supplemented with cell factors, and CD133+/CD133- cells were subsequently sorted using an indirect CD133 microbead kit. In vitro differentiation and tumorigenicity assays in BABA/c nude mice were performed to determine whether the CD133+ cells also possessed stem cell characteristics, in addition to the COLO 205 and CD133- cells. RNA sequencing was employed for the analysis of differential gene expression levels at the mRNA level, which was determined using reverse transcription-quantitative polymerase chain reaction. The mRNA expression levels of 43 genes varied in all three types of colon cancer cells (false discovery rate ≤0.05; fold change ≥2). Of these 43 genes, 30 were differentially expressed (8 upregulated and 22 downregulated) in the COLO 205 cells, as compared with the CD133- cells, and 6 genes (all downregulated) were differentially expressed in the COLO 205 cells, as compared with CD133+ cells. A total of 18 genes (10 upregulated and 8 downregulated) were differentially expressed in the CD133- cells, as compared with the CD133+ cells. By contrast, 6 genes were downregulated and none were upregulated in the CD133+ cells compared with the COLO 205 cells. These findings suggest that CD133+ cells may possess the same DNA repair capacity as COLO 205 cells. Heterogeneity in the expression profile of DNA damage repair genes was observed in COLO 205 cells, and COLO 205-derived CD133- cells and CD133+ cells may therefore provide a reference for molecular diagnosis, therapeutic target selection and determination of the treatment and prognosis for colorectal cancer.
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Affiliation(s)
- Yuhong Lu
- College of Basic Medicine, Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Xin Zhou
- Deparment of Gastroenterological Surgery, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Qingliang Zeng
- Deparment of Gastroenterological Surgery, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Daishun Liu
- Zunyi Key Laboratory of Genetic Diagnosis and Targeted Drug Therapy, The First People's Hospital of Zunyi, Zunyi, Guizhou 563003, P.R. China
| | - Changwu Yue
- Zunyi Key Laboratory of Genetic Diagnosis and Targeted Drug Therapy, The First People's Hospital of Zunyi, Zunyi, Guizhou 563003, P.R. China
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Srouji JR, Xu A, Park A, Kirsch JF, Brenner SE. The evolution of function within the Nudix homology clan. Proteins 2017; 85:775-811. [PMID: 27936487 PMCID: PMC5389931 DOI: 10.1002/prot.25223] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 10/15/2016] [Accepted: 11/28/2016] [Indexed: 01/01/2023]
Abstract
The Nudix homology clan encompasses over 80,000 protein domains from all three domains of life, defined by homology to each other. Proteins with a domain from this clan fall into four general functional classes: pyrophosphohydrolases, isopentenyl diphosphate isomerases (IDIs), adenine/guanine mismatch-specific adenine glycosylases (A/G-specific adenine glycosylases), and nonenzymatic activities such as protein/protein interaction and transcriptional regulation. The largest group, pyrophosphohydrolases, encompasses more than 100 distinct hydrolase specificities. To understand the evolution of this vast number of activities, we assembled and analyzed experimental and structural data for 205 Nudix proteins collected from the literature. We corrected erroneous functions or provided more appropriate descriptions for 53 annotations described in the Gene Ontology Annotation database in this family, and propose 275 new experimentally-based annotations. We manually constructed a structure-guided sequence alignment of 78 Nudix proteins. Using the structural alignment as a seed, we then made an alignment of 347 "select" Nudix homology domains, curated from structurally determined, functionally characterized, or phylogenetically important Nudix domains. Based on our review of Nudix pyrophosphohydrolase structures and specificities, we further analyzed a loop region downstream of the Nudix hydrolase motif previously shown to contact the substrate molecule and possess known functional motifs. This loop region provides a potential structural basis for the functional radiation and evolution of substrate specificity within the hydrolase family. Finally, phylogenetic analyses of the 347 select protein domains and of the complete Nudix homology clan revealed general monophyly with regard to function and a few instances of probable homoplasy. Proteins 2017; 85:775-811. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- John R. Srouji
- Plant and Microbial Biology DepartmentUniversity of CaliforniaBerkeleyCalifornia94720
- Molecular and Cell Biology DepartmentUniversity of CaliforniaBerkeleyCalifornia94720
- Present address: Molecular and Cellular Biology DepartmentHarvard UniversityCambridgeMassachusetts02138
| | - Anting Xu
- Graduate Study in Comparative Biochemistry, University of CaliforniaBerkeleyCalifornia94720
| | - Annsea Park
- Molecular and Cell Biology DepartmentUniversity of CaliforniaBerkeleyCalifornia94720
| | - Jack F. Kirsch
- Molecular and Cell Biology DepartmentUniversity of CaliforniaBerkeleyCalifornia94720
- Graduate Study in Comparative Biochemistry, University of CaliforniaBerkeleyCalifornia94720
| | - Steven E. Brenner
- Plant and Microbial Biology DepartmentUniversity of CaliforniaBerkeleyCalifornia94720
- Molecular and Cell Biology DepartmentUniversity of CaliforniaBerkeleyCalifornia94720
- Graduate Study in Comparative Biochemistry, University of CaliforniaBerkeleyCalifornia94720
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13
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Arif SM, Patil AG, Varshney U, Vijayan M. Biochemical and structural studies of Mycobacterium smegmatis MutT1, a sanitization enzyme with unusual modes of association. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2017; 73:349-364. [PMID: 28375146 DOI: 10.1107/s2059798317002534] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 02/14/2017] [Indexed: 01/12/2023]
Abstract
Mycobacterium smegmatis MutT1, which is made up of a Nudix domain (domain 1) and a histidine phosphatase domain (domain 2), efficiently hydrolyses 8-oxo-GTP and 8-oxo-dGTP to the corresponding nucleoside diphosphates and phosphate in the presence of magnesium ions. Domain 1 alone hydrolyses nucleoside triphosphates less efficiently. Under high concentrations and over long periods, the full-length enzyme as well as domain 1 catalyses the hydrolysis of the nucleoside triphosphates to the respective nucleoside monophosphates and pyrophosphate. The role of domain 2 appears to be limited to speeding up the reaction. Crystal structures of the apoenzyme and those of ligand-bound enzyme prepared in the presence of 8-oxo-GTP or 8-oxo-dGTP and different concentrations of magnesium were determined. In all of the structures except one, the molecules arrange themselves in a head-to-tail fashion in which domain 1 is brought into contact with domain 2 (trans domain 2) of a neighbouring molecule. The binding site for NTP (site A) is almost exclusively made up of residues from domain 1, while those for NDP (site B) and NMP (site C) are at the interface between domain 1 and trans domain 2 in an unusual instance of intermolecular interactions leading to binding sites. Protein-ligand interactions at site A lead to a proposal for the mechanism of hydrolysis of NTP to NDP and phosphate. A small modification in site A in the crystal which does not exhibit the head-to-tail arrangement appears to facilitate the production of NMP and pyrophosphate from NTP. The two arrangements could be in dynamic equilibrium in the cellular milieu.
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Affiliation(s)
- S M Arif
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India
| | - A G Patil
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560 012, India
| | - U Varshney
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560 012, India
| | - M Vijayan
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India
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14
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Understanding the molecular mechanism for the differential inhibitory activities of compounds against MTH1. Sci Rep 2017; 7:40557. [PMID: 28074893 PMCID: PMC5225434 DOI: 10.1038/srep40557] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 12/08/2016] [Indexed: 01/18/2023] Open
Abstract
MTH1 can hydrolyze oxidized nucleotides and is required for cancer survival. The IC50 values were 0.8 nM for TH287 with a methyl substitution, 5.0 nM for TH588 with a cyclopropyl substitution, and 2.1 μM for TH650 with an oxetanyl substitution. Thus, it is very significant to understand inhibitory mechanisms of these structurally similar compounds against MTH1 and influences of the substituent on the bioactivities. Our MD researches indicate that TH287 maintains significant hydrogen bonds with Asn33 and Asp119, stabilizes the binding site, and induces MTH1 adopt a closed motion, leading to a high inhibitory activity. When bound with TH588, the binding site can be partially stabilized and take a semi-closed state, which is because the cyclopropyl group in TH588 has larger steric hindrance than a methyl group in TH287. So TH588 has a slightly reduced inhibitory activity compared to TH287. TH650 induces greater conformation fluctuations than TH588 and the binding site adopts an opening state, which is caused by the large bulk of oxetanyl group and the interference of solvent on the oxetanyl substituent, leading to the lowest inhibitory activity. Thus, the inhibitory activity follows a TH287 > TH588 > TH650 trend, which well matches with the experimental finding.
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15
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Waz S, Nakamura T, Hirata K, Koga-Ogawa Y, Chirifu M, Arimori T, Tamada T, Ikemizu S, Nakabeppu Y, Yamagata Y. Structural and Kinetic Studies of the Human Nudix Hydrolase MTH1 Reveal the Mechanism for Its Broad Substrate Specificity. J Biol Chem 2016; 292:2785-2794. [PMID: 28035004 PMCID: PMC5314174 DOI: 10.1074/jbc.m116.749713] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 12/23/2016] [Indexed: 01/29/2023] Open
Abstract
The human MutT homolog 1 (hMTH1, human NUDT1) hydrolyzes oxidatively damaged nucleoside triphosphates and is the main enzyme responsible for nucleotide sanitization. hMTH1 recently has received attention as an anticancer target because hMTH1 blockade leads to accumulation of oxidized nucleotides in the cell, resulting in mutations and death of cancer cells. Unlike Escherichia coli MutT, which shows high substrate specificity for 8-oxoguanine nucleotides, hMTH1 has broad substrate specificity for oxidized nucleotides, including 8-oxo-dGTP and 2-oxo-dATP. However, the reason for this broad substrate specificity remains unclear. Here, we determined crystal structures of hMTH1 in complex with 8-oxo-dGTP or 2-oxo-dATP at neutral pH. These structures based on high quality data showed that the base moieties of two substrates are located on the similar but not the same position in the substrate binding pocket and adopt a different hydrogen-bonding pattern, and both triphosphate moieties bind to the hMTH1 Nudix motif (i.e. the hydrolase motif) similarly and align for the hydrolysis reaction. We also performed kinetic assays on the substrate-binding Asp-120 mutants (D120N and D120A), and determined their crystal structures in complex with the substrates. Analyses of bond lengths with high-resolution X-ray data and the relationship between the structure and enzymatic activity revealed that hMTH1 recognizes the different oxidized nucleotides via an exchange of the protonation state at two neighboring aspartate residues (Asp-119 and Asp-120) in its substrate binding pocket. To our knowledge, this mechanism of broad substrate recognition by enzymes has not been reported previously and may have relevance for anticancer drug development strategies targeting hMTH1.
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Affiliation(s)
- Shaimaa Waz
- From the Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto 862-0973
| | - Teruya Nakamura
- From the Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto 862-0973.,the Priority Organization for Innovation and Excellence, Kumamoto University, Kumamoto 862-0973
| | - Keisuke Hirata
- From the Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto 862-0973
| | - Yukari Koga-Ogawa
- From the Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto 862-0973
| | - Mami Chirifu
- From the Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto 862-0973
| | - Takao Arimori
- the Quantum Beam Science Research Directorate, National Institutes for Quantum and Radiological Science and Technology, Tokai, Ibaraki 319-1106, and
| | - Taro Tamada
- the Quantum Beam Science Research Directorate, National Institutes for Quantum and Radiological Science and Technology, Tokai, Ibaraki 319-1106, and
| | - Shinji Ikemizu
- From the Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto 862-0973
| | - Yusaku Nakabeppu
- the Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan
| | - Yuriko Yamagata
- From the Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto 862-0973,
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16
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Xia LL, Tang YB, Song FF, Xu L, Ji P, Wang SJ, Zhu JM, Zhang Y, Zhao GP, Wang Y, Liu TT. DCTPP1 attenuates the sensitivity of human gastric cancer cells to 5-fluorouracil by up-regulating MDR1 expression epigenetically. Oncotarget 2016; 7:68623-68637. [PMID: 27612427 PMCID: PMC5356578 DOI: 10.18632/oncotarget.11864] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 08/24/2016] [Indexed: 01/08/2023] Open
Abstract
Gastric cancer (GC) is among the most malignant cancers with high incidence and poor prognoses worldwide as well as in China. dCTP pyrophosphatase 1 (DCTPP1) is overexpressed in GC with a poor prognosis. Given chemotherapeutic drugs share similar structures with pyrimidine nucleotides, the role of DCTPP1 in affecting the drug sensitivity in GC remains unclear and is worthy of investigation. In the present study, we reported that DCTPP1-knockdown GC cell line BGC-823 exhibited more sensitivity to 5-fluorouracil (5-FU), demonstrated by the retardation of cell proliferation, the increase in cell apoptosis, cell cycle arrest at S phase and more DNA damages. Multidrug resistance 1 (MDR1) expression was unexpectedly down-regulated in DCTPP1-knockdown BGC-823 cells together with more intracellular 5-FU accumulation. This was in large achieved by the elevated methylation in promoter region of MDR1 gene. The intracellular 5-methyl-dCTP level increased in DCTPP1-knockdown BGC-823 cells as well. More significantly, the strong correlation of DCTPP1 and MDR1 expression was detectable in clinical GC samples. Our results thus imply a novel mechanism of chemoresistance mediated by the overexpression of DCTPP1 in GC. It is achieved partially through decreasing the concentration of intracellular 5-methyl-dCTP, which in turn results in promoter hypomethylation and hyper-expression of drug resistant gene MDR1. Our study suggests DCTPP1 as a potential indicative biomarker for the predication of chemoresistance in GC.
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Affiliation(s)
- Li-liang Xia
- State Key Laboratory of Genetic Engineering, Department of Microbiology, School of Life Sciences and Institute of Biomedical Sciences, Fudan University, Shanghai, China
- Shanghai-MOST Key Laboratory of Health and Disease Genomics, Chinese National Human Genome Center at Shanghai, Shanghai, China
| | - Ya-bin Tang
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, Department of Pharmacology and Chemical Biology, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Fei-fei Song
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, Department of Pharmacology and Chemical Biology, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Ling Xu
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, Department of Pharmacology and Chemical Biology, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Ping Ji
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, Department of Pharmacology and Chemical Biology, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Shu-jun Wang
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, Department of Pharmacology and Chemical Biology, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Ji-min Zhu
- Department of Gastroenterology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Yong Zhang
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, Department of Pharmacology and Chemical Biology, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Guo-ping Zhao
- State Key Laboratory of Genetic Engineering, Department of Microbiology, School of Life Sciences and Institute of Biomedical Sciences, Fudan University, Shanghai, China
- Shanghai-MOST Key Laboratory of Health and Disease Genomics, Chinese National Human Genome Center at Shanghai, Shanghai, China
- Department of Microbiology and Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong SAR, China
| | - Ying Wang
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, Department of Pharmacology and Chemical Biology, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Tao-tao Liu
- Department of Gastroenterology, Zhongshan Hospital, Fudan University, Shanghai, China
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17
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Stewart JJP. A method for predicting individual residue contributions to enzyme specificity and binding-site energies, and its application to MTH1. J Mol Model 2016; 22:259. [PMID: 27714533 PMCID: PMC5054044 DOI: 10.1007/s00894-016-3119-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 09/08/2016] [Indexed: 12/20/2022]
Abstract
A new method for predicting the energy contributions to substrate binding and to specificity has been developed. Conventional global optimization methods do not permit the subtle effects responsible for these properties to be modeled with sufficient precision to allow confidence to be placed in the results, but by making simple alterations to the model, the precisions of the various energies involved can be improved from about ±2 kcal mol−1 to ±0.1 kcal mol−1. This technique was applied to the oxidized nucleotide pyrophosphohydrolase enzyme MTH1. MTH1 is unusual in that the binding and reaction sites are well separated—an advantage from a computational chemistry perspective, as it allows the energetics involved in docking to be modeled without the need to consider any issues relating to reaction mechanisms. In this study, two types of energy terms were investigated: the noncovalent interactions between the binding site and the substrate, and those responsible for discriminating between the oxidized nucleotide 8-oxo-dGTP and the normal dGTP. Both of these were investigated using the semiempirical method PM7 in the program MOPAC. The contributions of the individual residues to both the binding energy and the specificity of MTH1 were calculated by simulating the effect of mutations. Where comparisons were possible, all calculated results were in agreement with experimental observations. This technique provides fresh insight into the binding mechanism that enzymes use for discriminating between possible substrates.
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Affiliation(s)
- James J P Stewart
- Stewart Computational Chemistry, 15210 Paddington Circle, Colorado Springs, CO, 80921, USA.
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18
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Zhou S, Wang M, Tong Z, Wang J. The recognition mechanism of crizotinib on MTH1: influence of chirality on the bioactivity. Mol Phys 2016. [DOI: 10.1080/00268976.2016.1145750] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Shuilian Zhou
- Department of Pharmaceutical Engineering, School of Chemistry and Chemical Engineering, Guangxi University, Nanning, People's Republic of China
| | - Mian Wang
- Department of Pharmaceutical Engineering, School of Chemistry and Chemical Engineering, Guangxi University, Nanning, People's Republic of China
| | - Zhangfa Tong
- Department of Pharmaceutical Engineering, School of Chemistry and Chemical Engineering, Guangxi University, Nanning, People's Republic of China
| | - Jianyi Wang
- Department of Pharmaceutical Engineering, School of Chemistry and Chemical Engineering, Guangxi University, Nanning, People's Republic of China
- Department of Pharmaceutical Engineering, Guangxi Colleges and Universities Key Laboratory of Applied Chemistry Technology and Resource Development, Nanning, People's Republic of China
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19
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Rampazzo C, Tozzi MG, Dumontet C, Jordheim LP. The druggability of intracellular nucleotide-degrading enzymes. Cancer Chemother Pharmacol 2015; 77:883-93. [PMID: 26614508 DOI: 10.1007/s00280-015-2921-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 11/13/2015] [Indexed: 01/24/2023]
Abstract
Nucleotide metabolism is the target of a large number of anticancer drugs including antimetabolites and specific enzyme inhibitors. We review scientific findings that over the last 10-15 years have allowed the identification of several intracellular nucleotide-degrading enzymes as cancer drug targets, and discuss further potential therapeutic applications for Rcl, SAMHD1, MTH1 and cN-II. We believe that enzymes involved in nucleotide metabolism represent potent alternatives to conventional cancer chemotherapy targets.
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Affiliation(s)
- Chiara Rampazzo
- Department of Biology, University of Padova, 35131, Padua, Italy
| | - Maria Grazia Tozzi
- Department of Biology, Biochemistry Unit, University of Pisa, Pisa, Italy
| | - Charles Dumontet
- Université de Lyon, 69000, Lyon, France.,Université de Lyon 1, 69622, Lyon, France.,Université de Lyon 1, 69000, Lyon, France.,INSERM U1052, Centre de Recherche en Cancérologie de Lyon, 69000, Lyon, France.,CNRS UMR 5286, Centre de Recherche en Cancérologie de Lyon, 69000, Lyon, France.,Centre Léon Bérard, 69008, Lyon, France.,Hospices Civils de Lyon, 69000, Lyon, France
| | - Lars Petter Jordheim
- Université de Lyon, 69000, Lyon, France. .,Université de Lyon 1, 69622, Lyon, France. .,Université de Lyon 1, 69000, Lyon, France. .,INSERM U1052, Centre de Recherche en Cancérologie de Lyon, 69000, Lyon, France. .,CNRS UMR 5286, Centre de Recherche en Cancérologie de Lyon, 69000, Lyon, France. .,Centre Léon Bérard, 69008, Lyon, France. .,Equipe Anticorps-Anticancer, INSERM U1052 - CNRS UMR 5286, Faculté Rockefeller, Centre de Recherche en Cancérologie de Lyon, 8 avenue Rockefeller, 69008, Lyon, France.
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20
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Human dCTP pyrophosphatase 1 promotes breast cancer cell growth and stemness through the modulation on 5-methyl-dCTP metabolism and global hypomethylation. Oncogenesis 2015; 4:e159. [PMID: 26075750 PMCID: PMC4491611 DOI: 10.1038/oncsis.2015.10] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 03/24/2015] [Accepted: 04/02/2015] [Indexed: 12/11/2022] Open
Abstract
Human DCTPP1 (dCTP pyrophosphatase 1), also known as XTP3-transactivated protein A, belongs to MazG-like nucleoside triphosphate pyrophosphatase (NTP-PPase) superfamily. Being a newly identified pyrophosphatase, its relevance to tumorigenesis and the mechanisms are not well investigated. In the present study, we have confirmed our previous study that DCTPP1 was significantly hyperexpressed in breast cancer and further demonstrated its strong association with tumor progression and poor prognosis in breast cancer. Knockdown of DCTPP1 in breast cancer cell line MCF-7 cells remarkably retarded proliferation and colony formation in vitro. The capacity of mammosphere formation of MCF-7 was suppressed with the silence of DCTPP1, which was consistent with the enhanced mammosphere-forming ability in DCTPP1-overexpressed MDA-MB-231 cells. To further dissect the mechanisms of DCTPP1 in promoting tumor cell growth and stemness maintenance, its biochemical properties and biological functions were investigated. DCTPP1 displayed bioactive form with tetrameric structure similar to other MazG domain-containing pyrophosphatases based on structure simulation. A substrate preference for dCTP and its methylated or halogen-modified derivatives over the other canonical (deoxy-) NTPs was demonstrated from enzymatic assay. This substrate preference was also proved in breast cancer cells that the intracellular 5-methyl-dCTP level increased in DCTPP1-deficient MCF-7 cells but decreased in DCTPP1-overexpressed MDA-MB-231 cells. Moreover, global methylation level was elevated in DCTPP1-knockdown MCF-7 cells or mammosphere-forming MCF-7 cells but decreased significantly in DCTPP1-overexpressed MDA-MB-231 cells and its mammospheres. Our results thus indicated that human DCTPP1 was capable of modulating the concentration of intracellular 5-methyl-dCTP. This in turn affected global methylation, contributing to a known phenomenon of hypomethylation related to the cancer cell growth and stemness maintenance. Our current investigations point to the pathological functions of DCTPP1 overexpression in breast cancer cells with aberrant dCTP metabolism and epigenetic modification.
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21
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Lian K, Leiros HKS, Moe E. MutT from the fish pathogen Aliivibrio salmonicida is a cold-active nucleotide-pool sanitization enzyme with unexpectedly high thermostability. FEBS Open Bio 2015; 5:107-16. [PMID: 25737836 PMCID: PMC4338371 DOI: 10.1016/j.fob.2015.01.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Revised: 01/13/2015] [Accepted: 01/27/2015] [Indexed: 02/08/2023] Open
Abstract
Upon infection by pathogenic bacteria, production of reactive oxygen species (ROS) is part of the host organism's first line of defence. ROS damage a number of macromolecules, and in order to withstand such a harsh environment, the bacteria need to have well-functioning ROS scavenging and repair systems. Herein, MutT is an important nucleotide-pool sanitization enzyme, which degrades 8-oxo-dGTP and thus prevents it from being incorporated into DNA. In this context, we have performed a comparative biochemical and structural analysis of MutT from the fish pathogen Aliivibrio salmonicida (AsMutT) and the human pathogen Vibrio cholerae (VcMutT), in order to analyse their function as nucleotide sanitization enzymes and also determine possible cold-adapted properties of AsMutT. The biochemical characterisation revealed that both enzymes possess activity towards the 8-oxo-dGTP substrate, and that AsMutT has a higher catalytic efficiency than VcMutT at all temperatures studied. Calculations based on the biochemical data also revealed a lower activation energy (E a) for AsMutT compared to VcMutT, and differential scanning calorimetry experiments showed that AsMutT displayed an unexpected higher melting temperature (T m) value than VcMutT. A comparative analysis of the crystal structure of VcMutT, determined to 2.42 Å resolution, and homology models of AsMutT indicate that three unique Gly residues in loops of VcMutT, and additional long range ion-pairs in AsMutT could explain the difference in temperature stability of the two enzymes. We conclude that AsMutT is a stable, cold-active enzyme with high catalytic efficiency and reduced E a, compared to the mesophilic VcMutT.
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Affiliation(s)
- Kjersti Lian
- The Norwegian Structural Biology Center (NorStruct), Department of Chemistry, The Arctic University of Norway, 9037 Tromsø, Norway
| | - Hanna-Kirsti S Leiros
- The Norwegian Structural Biology Center (NorStruct), Department of Chemistry, The Arctic University of Norway, 9037 Tromsø, Norway
| | - Elin Moe
- The Norwegian Structural Biology Center (NorStruct), Department of Chemistry, The Arctic University of Norway, 9037 Tromsø, Norway ; Macromolecular Crystallography Unit, Instituto de Tecnologia Química e Biológica (ITQB), Universidade Nova de Lisboa, Av. da República - EAN, 2780-157 Oeiras, Portugal
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22
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Fujiwara SI, Sawada K, Amisaki T. Molecular dynamics study on conformational differences between dGMP and 8-oxo-dGMP: Effects of metal ions. J Mol Graph Model 2014; 51:158-67. [PMID: 24929814 DOI: 10.1016/j.jmgm.2014.05.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Revised: 05/09/2014] [Accepted: 05/22/2014] [Indexed: 01/05/2023]
Abstract
The modified nucleotide base 7,8-dihydro-8-oxo-guanine (8-oxo-G) is one of the major sources of spontaneous mutagenesis. Nucleotide-sanitizing enzymes, such as the MutT homolog-1 (MTH1) and nudix-type motif 5 (NUDT5), selectively remove 8-oxo-G from the cellular pool of nucleotides. Previous studies showed that, although the syn conformation generally predominates in purine nucleotides with a bulky substituent at the 8-position, 8-oxo-dGMP binds to both MTH1 and NUDT5 in the anti conformation. This study was initiated to investigate the possibility that 8-oxo-dGMP itself may adopt the anti conformation. Molecular dynamics simulations of mononucleotides (dGMP, 8-oxo-dGMP) in aqueous solution were performed. 8-oxo-dGMP adopted the anti conformation as well as the syn conformation, and the proportion of adopting the anti conformation increased in the presence of metal ions. When 8-oxo-dGMP was in the anti conformation, a metal ion was located between the oxygen atom of phosphate and the oxygen atom at the 8-position of 8-oxo-G. The types of stable anti conformations of 8-oxo-dGMP differed, depending on the ionic radii and charges of coexisting ions. These data suggested a role for metal ions, other than as cofactors for the hydrolysis of the di- and tri-phosphate forms of mononucleotides; that the metal ions help retain the anti conformation of the N-glycosidic torsion angle of 8-oxo-dGMP to promote the binding between the 8-oxo-G deoxynucleotide and the nucleotide-sanitizing enzymes.
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Affiliation(s)
- Shin-Ichi Fujiwara
- Department of Biological Regulation, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago 683-8503, Japan.
| | - Kenichiro Sawada
- Department of Biological Regulation, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago 683-8503, Japan
| | - Takashi Amisaki
- Department of Biological Regulation, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago 683-8503, Japan
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23
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Streib M, Kräling K, Richter K, Xie X, Steuber H, Meggers E. Ein metallorganischer Inhibitor des humanen Reparaturenzyms 7,8-Dihydro-8-oxoguanosin-Triphosphatase. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201307849] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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24
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Streib M, Kräling K, Richter K, Xie X, Steuber H, Meggers E. An organometallic inhibitor for the human repair enzyme 7,8-dihydro-8-oxoguanosine triphosphatase. Angew Chem Int Ed Engl 2013; 53:305-9. [PMID: 24258965 DOI: 10.1002/anie.201307849] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Indexed: 12/31/2022]
Abstract
The probe-based discovery of the first small-molecule inhibitor of the repair enzyme 8-oxo-dGTPase (MTH1) is presented, which is an unconventional cyclometalated ruthenium half-sandwich complex. The organometallic inhibitor with low-nanomolar activity displays astonishing specificity, as verified in tests with an extended panel of protein kinases and other ATP binding proteins. The binding of the organometallic inhibitor to MTH1 is investigated by protein crystallography.
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Affiliation(s)
- Manuel Streib
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35043 Marburg (Germany)
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25
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Patil AGG, Sang PB, Govindan A, Varshney U. Mycobacterium tuberculosis MutT1 (Rv2985) and ADPRase (Rv1700) proteins constitute a two-stage mechanism of 8-oxo-dGTP and 8-oxo-GTP detoxification and adenosine to cytidine mutation avoidance. J Biol Chem 2013; 288:11252-62. [PMID: 23463507 PMCID: PMC3630869 DOI: 10.1074/jbc.m112.442566] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 01/28/2013] [Indexed: 11/06/2022] Open
Abstract
Approximately one third of the world population is infected with Mycobacterium tuberculosis, the causative agent of tuberculosis. A better understanding of the pathogen biology is crucial to develop new tools/strategies to tackle its spread and treatment. In the host macrophages, the pathogen is exposed to reactive oxygen species, known to damage dGTP and GTP to 8-oxo-dGTP and 8-oxo-GTP, respectively. Incorporation of the damaged nucleotides in nucleic acids is detrimental to organisms. MutT proteins, belonging to a class of Nudix hydrolases, hydrolyze 8-oxo-G nucleoside triphosphates/diphosphates to the corresponding nucleoside monophosphates and sanitize the nucleotide pool. Mycobacteria possess several MutT proteins. However, a functional homolog of Escherichia coli MutT has not been identified. Here, we characterized MtuMutT1 and Rv1700 proteins of M. tuberculosis. Unlike other MutT proteins, MtuMutT1 converts 8-oxo-dGTP to 8-oxo-dGDP, and 8-oxo-GTP to 8-oxo-GDP. Rv1700 then converts them to the corresponding nucleoside monophosphates. This observation suggests the presence of a two-stage mechanism of 8-oxo-dGTP/8-oxo-GTP detoxification in mycobacteria. MtuMutT1 converts 8-oxo-dGTP to 8-oxo-dGDP with a Km of ∼50 μM and Vmax of ∼0.9 pmol/min per ng of protein, and Rv1700 converts 8-oxo-dGDP to 8-oxo-dGMP with a Km of ∼9.5 μM and Vmax of ∼0.04 pmol/min per ng of protein. Together, MtuMutT1 and Rv1700 offer maximal rescue to E. coli for its MutT deficiency by decreasing A to C mutations (a hallmark of MutT deficiency). We suggest that the concerted action of MtuMutT1 and Rv1700 plays a crucial role in survival of bacteria against oxidative stress.
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Affiliation(s)
- Aravind Goud G. Patil
- From the Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India and
| | - Pau Biak Sang
- From the Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India and
| | - Ashwin Govindan
- From the Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India and
| | - Umesh Varshney
- From the Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India and
- the Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India
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Koga Y, Inazato M, Nakamura T, Hashikawa C, Chirifu M, Michi A, Yamashita T, Toma S, Kuniyasu A, Ikemizu S, Nakabeppu Y, Yamagata Y. Crystallization and preliminary X-ray analysis of human MTH1 with a homogeneous N-terminus. Acta Crystallogr Sect F Struct Biol Cryst Commun 2012; 69:45-8. [PMID: 23295485 DOI: 10.1107/s1744309112048002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Accepted: 11/21/2012] [Indexed: 11/10/2022]
Abstract
Human MTH1 (hMTH1) is an enzyme that hydrolyses several oxidized purine nucleoside triphosphates to their corresponding nucleoside monophosphates. Crystallographic studies have shown that the accurate mode of interaction between 8-oxoguanine and hMTH1 cannot be understood without determining the positions of the H atoms, as can be observed in neutron and/or ultrahigh-resolution X-ray diffraction studies. The hMTH1 protein prepared in the original expression system from Escherichia coli did not appear to be suitable for obtaining high-quality crystals because the hMTH1 protein had heterogeneous N-termini of Met1 and Gly2 that resulted from N-terminal Met excision by methionine aminopeptidase from the E. coli host. To obtain homogeneous hMTH1, the Gly at the second position was replaced by Lys. As a result, mutant hMTH1 protein [hMTH1(G2K)] with a homogeneous N-terminus could be prepared and high-quality crystals which diffracted to near 1.1 Å resolution using synchrotron radiation were produced. The new crystals belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 46.36, b = 47.58, c = 123.89 Å.
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Affiliation(s)
- Yukari Koga
- Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto 862-0973, Japan
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27
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Feng Y, Liu L, Wang J, Liu J, Hu W, Wang X, Yang Z. Integrated refolding techniques for Schistosoma japonicum MTH1 overexpressed as inclusion bodies in Escherichia coli. Protein Expr Purif 2012; 84:181-7. [PMID: 22641057 DOI: 10.1016/j.pep.2012.05.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Revised: 05/08/2012] [Accepted: 05/14/2012] [Indexed: 12/25/2022]
Abstract
The full-length cDNA of MTH1in Schistosoma japonicum was previously isolated. However, insoluble protein expression in Escherichia coli is the biggest bottleneck limiting biological and biophysical studies. Protein aggregation could not be significantly prevented using solubilization or refolding techniques, and denatured MTH1 protein could not be refolded to the native monomer form. Hence, integrating several refolding techniques within the protein refolding process of MTH1, a large amount of active MTH1 was obtained for protein crystallization. We primarily utilized the two-step-denaturing and refolding method and the protein refolding screening technique, as well as the continuous dialysis method. First, we identified the refolding buffer composition that allowed for successful refolding to overcome protein precipitation. Next, we used the two-step-denaturing and refolding method and the continuous dialysis method to suppress protein aggregation. In the end, we obtained 15 mg of active MTH1 monomer with 95% purity from 0.5l medium. Integrated refolding techniques proved to be excellent for obtaining the native monomer of S. japonicum MTH1 from inclusion bodies, paving the way for future biological and biophysical studies.
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Affiliation(s)
- Yanye Feng
- State Key Laboratory of Bioreactor Engineering, School of Biotechnology, East China University of Science and Technology, Shanghai 200237, China.
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28
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Kawasaki K, Kanaba T, Yoneyama M, Murata-Kamiya N, Kojima C, Ito Y, Kamiya H, Mishima M. Insights into substrate recognition by the Escherichia coli Orf135 protein through its solution structure. Biochem Biophys Res Commun 2012; 420:263-8. [PMID: 22414689 DOI: 10.1016/j.bbrc.2012.02.146] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2012] [Accepted: 02/27/2012] [Indexed: 11/28/2022]
Abstract
Escherichia coli Orf135 hydrolyzes oxidatively damaged nucleotides such as 2-hydroxy-dATP, 8-oxo-dGTP and 5-hydroxy-CTP, in addition to 5-methyl-dCTP, dCTP and CTP. Nucleotide pool sanitization by Orf135 is important since nucleotides are continually subjected to potential damage by reactive oxygen species produced during respiration. Orf135 is a member of the Nudix family of proteins which hydrolyze nucleoside diphosphate derivatives. Nudix hydrolases are characterized by the presence of a conserved motif, even though they recognize various substrates and possess a variety of substrate binding pockets. We investigated the tertiary structure of Orf135 and its interaction with a 2-hydroxy-dATP analog using NMR. We report on the solution structure of Orf135, which should contribute towards a structural understanding of Orf135 and its interaction with substrates.
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Affiliation(s)
- Kumiko Kawasaki
- Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minamiosawa, Hachioji 192-0397, Japan
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29
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Svensson LM, Jemth AS, Desroses M, Loseva O, Helleday T, Högbom M, Stenmark P. Crystal structure of human MTH1 and the 8-oxo-dGMP product complex. FEBS Lett 2011; 585:2617-21. [PMID: 21787772 DOI: 10.1016/j.febslet.2011.07.017] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 07/04/2011] [Accepted: 07/13/2011] [Indexed: 11/24/2022]
Abstract
MTH1 hydrolyzes oxidized nucleotide triphosphates, thereby preventing them from being incorporated into DNA. We here present the structures of human MTH1 (1.9Å) and its complex with the product 8-oxo-dGMP (1.8Å). Unexpectedly MTH1 binds the nucleotide in the anti conformation with no direct interaction between the 8-oxo group and the protein. We suggest that the specificity depends on the stabilization of an enol tautomer of the 8-oxo form of dGTP. The binding of the product induces no major structural changes. The structures reveal the mode of nucleotide binding in MTH1 and provide the structural basis for inhibitor design.
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Affiliation(s)
- Linda M Svensson
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
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30
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Arimori T, Tamaoki H, Nakamura T, Kamiya H, Ikemizu S, Takagi Y, Ishibashi T, Harashima H, Sekiguchi M, Yamagata Y. Diverse substrate recognition and hydrolysis mechanisms of human NUDT5. Nucleic Acids Res 2011; 39:8972-83. [PMID: 21768126 PMCID: PMC3203587 DOI: 10.1093/nar/gkr575] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Human NUDT5 (hNUDT5) hydrolyzes various modified nucleoside diphosphates including 8-oxo-dGDP, 8-oxo-dADP and ADP-ribose (ADPR). However, the structural basis of the broad substrate specificity remains unknown. Here, we report the crystal structures of hNUDT5 complexed with 8-oxo-dGDP and 8-oxo-dADP. These structures reveal an unusually different substrate-binding mode. In particular, the positions of two phosphates (α and β phosphates) of substrate in the 8-oxo-dGDP and 8-oxo-dADP complexes are completely inverted compared with those in the previously reported hNUDT5–ADPR complex structure. This result suggests that the nucleophilic substitution sites of the substrates involved in hydrolysis reactions differ despite the similarities in the chemical structures of the substrates and products. To clarify this hypothesis, we employed the isotope-labeling method and revealed that 8-oxo-dGDP is attacked by nucleophilic water at Pβ, whereas ADPR is attacked at Pα. This observation reveals that the broad substrate specificity of hNUDT5 is achieved by a diversity of not only substrate recognition, but also hydrolysis mechanisms and leads to a novel aspect that enzymes do not always catalyze the reaction of substrates with similar chemical structures by using the chemically equivalent reaction site.
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Affiliation(s)
- Takao Arimori
- Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto 862-0973, Japan
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Richards EG, Zaveri HP, Wolf VL, Kang SHL, Scott DA. Delineation of a less than 200 kb minimal deleted region for cardiac malformations on chromosome 7p22. Am J Med Genet A 2011; 155A:1729-34. [PMID: 21671376 DOI: 10.1002/ajmg.a.34041] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Accepted: 03/20/2011] [Indexed: 01/11/2023]
Abstract
Cardiac malformations are commonly seen in individuals with terminal and interstitial deletions involving chromosome band 7p22. Although these malformations represent a significant cause of morbidity, the dosage-sensitive gene(s) that underlie these defects have yet to be identified. In this report, we describe a 16-month-old male with tetralogy of Fallot, bilateral second branchial arch remnants, and mild dysmorphic features. Array comparative genomic hybridization analysis revealed a less than 400 kb interstitial deletion on chromosome 7p22. The deletion was confirmed by real-time quantitative PCR and FISH analyses and was not detected in samples obtained from the child's parents. Molecular data from this de novo deletion, in combination with data from other isolated 7p deletions in the literature, can be used to define a less than 200 kb minimal deleted region for cardiac malformations on 7p22. This minimal deleted region spans all, or portions, of the coding regions of four known genes-MAD1L1, FTSJ2, NUDT1, and SNX8-and may include upstream regulatory elements of EIF3B. It is likely that one or more of these five genes, alone or in combination, plays an important, yet previously uncharacterized, role in cardiac development.
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Affiliation(s)
- Elliott G Richards
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
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32
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Nakabeppu Y, Oka S, Sheng Z, Tsuchimoto D, Sakumi K. Programmed cell death triggered by nucleotide pool damage and its prevention by MutT homolog-1 (MTH1) with oxidized purine nucleoside triphosphatase. Mutat Res 2010; 703:51-8. [PMID: 20542142 DOI: 10.1016/j.mrgentox.2010.06.006] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2010] [Accepted: 06/04/2010] [Indexed: 01/10/2023]
Abstract
Accumulation of oxidized bases such as 8-oxoguanine in either nuclear or mitochondrial DNA triggers various cellular dysfunctions including mutagenesis, and programmed cell death or senescence. Recent studies have revealed that oxidized nucleoside triphosphates such as 8-oxo-dGTP in the nucleotide pool are the main source of oxidized bases accumulating in the DNA of cells under oxidative stress. To counteract such deleterious effects of nucleotide pool damage, mammalian cells possess MutT homolog-1 (MTH1) with oxidized purine nucleoside triphosphatase and related enzymes, thus minimizing the accumulation of oxidized bases in cellular DNA. Depletion or increased expression of the MTH1 protein have revealed its significant roles in avoiding programmed cell death or senescence as well as mutagenesis, and accumulating evidences indicate that MTH1 is involved in suppression of degenerative disorders such as neurodegeneration.
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Affiliation(s)
- Yusaku Nakabeppu
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, Kyushu University 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
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Nakamura T, Meshitsuka S, Kitagawa S, Abe N, Yamada J, Ishino T, Nakano H, Tsuzuki T, Doi T, Kobayashi Y, Fujii S, Sekiguchi M, Yamagata Y. Structural and dynamic features of the MutT protein in the recognition of nucleotides with the mutagenic 8-oxoguanine base. J Biol Chem 2010; 285:444-52. [PMID: 19864691 PMCID: PMC2804192 DOI: 10.1074/jbc.m109.066373] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Revised: 10/14/2009] [Indexed: 11/06/2022] Open
Abstract
Escherichia coli MutT hydrolyzes 8-oxo-dGTP to 8-oxo-dGMP, an event that can prevent the misincorporation of 8-oxoguanine opposite adenine in DNA. Of the several enzymes that recognize 8-oxoguanine, MutT exhibits high substrate specificity for 8-oxoguanine nucleotides; however, the structural basis for this specificity is unknown. The crystal structures of MutT in the apo and holo forms and in the binary and ternary forms complexed with the product 8-oxo-dGMP and 8-oxo-dGMP plus Mn(2+), respectively, were determined. MutT strictly recognizes the overall conformation of 8-oxo-dGMP through a number of hydrogen bonds. This recognition mode revealed that 8-oxoguanine nucleotides are discriminated from guanine nucleotides by not only the hydrogen bond between the N7-H and Odelta (N119) atoms but also by the syn glycosidic conformation that 8-oxoguanine nucleotides prefer. Nevertheless, these discrimination factors cannot by themselves explain the roughly 34,000-fold difference between the affinity of MutT for 8-oxo-dGMP and dGMP. When the binary complex of MutT with 8-oxo-dGMP is compared with the ligand-free form, ordering and considerable movement of the flexible loops surrounding 8-oxo-dGMP in the binary complex are observed. These results indicate that MutT specifically recognizes 8-oxoguanine nucleotides by the ligand-induced conformational change.
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Affiliation(s)
- Teruya Nakamura
- From the Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto 862-0973
| | - Sachiko Meshitsuka
- the Graduate School of Pharmaceutical Sciences, Osaka University, Suita 565-0871
| | - Seiju Kitagawa
- the Graduate School of Pharmaceutical Sciences, Osaka University, Suita 565-0871
| | - Nanase Abe
- the Graduate School of Pharmaceutical Sciences, Osaka University, Suita 565-0871
| | - Junichi Yamada
- the Graduate School of Pharmaceutical Sciences, Osaka University, Suita 565-0871
| | - Tetsuya Ishino
- the Graduate School of Pharmaceutical Sciences, Osaka University, Suita 565-0871
| | - Hiroaki Nakano
- the Graduate School of Pharmaceutical Sciences, Osaka University, Suita 565-0871
| | - Teruhisa Tsuzuki
- the Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582
| | - Takefumi Doi
- the Graduate School of Pharmaceutical Sciences, Osaka University, Suita 565-0871
| | - Yuji Kobayashi
- the Graduate School of Pharmaceutical Sciences, Osaka University, Suita 565-0871
| | - Satoshi Fujii
- the School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka 422-8526, and
| | | | - Yuriko Yamagata
- From the Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto 862-0973
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Characterization of the vaccinia virus D10 decapping enzyme provides evidence for a two-metal-ion mechanism. Biochem J 2009; 420:27-35. [PMID: 19210265 DOI: 10.1042/bj20082296] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Decapping enzymes are required for the removal of the 5'-end cap of mRNAs. These enzymes exhibit a specific hydrolase activity, resulting in cleavage between the alpha- and beta-phosphates of the m7GpppN cap to generate both m7GDP and monophosphorylated RNA products. Decapping enzymes have been found in humans, plants and yeasts, and have been discovered more recently in vaccinia virus (D10 protein). Although experimental evidences are lacking, three-metal- and two-metal-ion mechanisms have been proposed so far for the decapping enzymes. In the present study, we performed a biochemical characterization of the interaction of bivalent cations with the vaccinia virus D10 protein. Synergistic activation of the enzyme was observed in the presence of Mg2+ and Mn2+ ions, suggesting the existence of two metal-ion-binding sites on the D10 protein. Moreover, dual-ligand titration experiments using fluorescence spectroscopy demonstrated the presence of two metal-ion-binding sites on the enzyme. A three-dimensional structural model of the active site of the enzyme was generated which highlighted the importance of three glutamate residues involved in the co-ordination of two metal ions and a water molecule. Mutational analyses confirmed the role of two glutamate residues for the binding of metal ions. We demonstrate that one metal ion is co-ordinated by Glu132, while the second metal ion is co-ordinated by Glu145. Taken together, these results support the proposed two-metal-ion mechanistic model for the D10 decapping enzyme.
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35
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Moreland NJ, Charlier C, Dingley AJ, Baker EN, Lott JS. Making sense of a missense mutation: characterization of MutT2, a Nudix hydrolase from Mycobacterium tuberculosis, and the G58R mutant encoded in W-Beijing strains of M. tuberculosis. Biochemistry 2009; 48:699-708. [PMID: 19115962 DOI: 10.1021/bi8009554] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Recent polymorphism analyses of Mycobacterium tuberculosis strains have identified missense mutations unique to the W-Beijing lineage in genes belonging to the Nudix hydrolase superfamily. This study investigates the structure and function of one of these Nudix hydrolases, MutT2, and examines the effect that the W-Beijing mutation (G58R) has on enzyme characteristics. MutT2 has a preference for cytidine triphosphates, and although the G58R mutation does not alter nucleotide specificity, it reduces the protein's affinity for divalent cations. The K(D) of free Mg(2+) is 79-fold higher for the G58R mutant (3.30 +/- 0.19 mM) compared with that for the wild-type (41.7 +/- 1.4 microM). Circular dichroism and nuclear magnetic resonance spectroscopy measurements show that while the mutation does not perturb the overall structure of the protein, protein stability is significantly compromised by the presence of the arginine with DeltaG (H(2)O), the free-energy of unfolding, being reduced by 2.48 kcal mol(-1) in the G58R mutant. Homology modeling of MutT2 shows that Gly-58 is in close proximity (10.8 A) to the Mg(2+) binding site formed by the highly conserved Nudix box residues and hydrogen bonds with Ala-54 in the preceding alpha-helix. This may explain the increased divalent cation requirement and decreased stability observed when an arginine is substituted for glycine at this position. A role for MutT2 in the regulation of cytidine-triphosphates available for nucleotide-dependent reactions is postulated, and the impact that the G58R mutation may have on these reactions is discussed.
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Affiliation(s)
- Nicole J Moreland
- Maurice Wilkins Centre for Molecular Biodiscovery and Laboratory of Structural Biology, School of Biological Sciences, University of Auckland, New Zealand.
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36
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Nakabeppu Y, Tsuchimoto D, Yamaguchi H, Sakumi K. Oxidative damage in nucleic acids and Parkinson's disease. J Neurosci Res 2007; 85:919-34. [PMID: 17279544 DOI: 10.1002/jnr.21191] [Citation(s) in RCA: 209] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Oxidative DNA lesions, such as 8-oxoguanine (8-oxoG), accumulate in nuclear and mitochondrial genomes during aging, and such accumulation can increase dramatically in patients with Parkinson's disease (PD). To counteract oxidative damage to nucleic acids, human and rodents are equipped with three distinct enzymes. One of these, MTH1, hydrolyzes oxidized purine nucleoside triphosphates, such as 8-oxo-2'-deoxyguanosine triphosphate and 2-hydroxy-2'-deoxyadenosine triphosphate, to their monophosphate forms. The other two enzymes are 8-oxoG DNA glycosylase encoded by the OGG1 gene and adenine/2-hydroxyadenine DNA glycosylase encoded by the MUTYH gene. We have shown a significant increase in 8-oxoG in mitochondrial DNA as well as an elevated expression of MTH1, OGG1, and MUTYH in nigrostriatal dopaminergic neurons of PD patients, suggesting that the buildup of these lesions may cause dopamine neuron loss. We established MTH1-null mice and found that MTH1-null fibroblasts were highly susceptible to cell death caused by H(2)O(2) characterized by pyknosis and electron-dense deposits in the mitochondria, and that this was accompanied by an ongoing accumulation of 8-oxoG in nuclear and mitochondrial DNA. We also showed that MTH1-null mice exhibited an increased accumulation of 8-oxoG in striatal mitochondrial DNA, followed by more extreme neuronal dysfunction after 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine administration than that of wild-type mice. In conclusion, oxidative damage in nucleic acids is likely to be a major risk factor for Parkinson's disease, indicating that a solid understanding of the defense mechanisms involved will enable us to develop new strategies for protecting the brain against oxidative stress.
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Affiliation(s)
- Yusaku Nakabeppu
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan.
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37
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Ye Y, Muller JG, Burrows CJ. Synthesis and characterization of the oxidized dGTP lesions spiroiminodihydantoin-2'-deoxynucleoside-5'- triphosphate and guanidinohydantoin-2'-deoxynucleoside-5'- triphosphate. J Org Chem 2007; 71:2181-4. [PMID: 16497015 PMCID: PMC2442819 DOI: 10.1021/jo052484t] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Two convenient synthetic routes to the oxidized guanosine triphosphate lesions spiroiminodihydantoin-2'-deoxynucleoside-5'-triphosphate (dSpTP) and guanidinohydantoin-2'-deoxynucleoside-5'-triphosphate (dGhTP) are reported. Both two-electron oxidation of 2'-deoxy-7,8-dihydro-8-oxoguanosine-5'-triphosphate (dOGTP) using SO4*- generated photolytically from K2S2O8 or four-electron oxidation of 2'-deoxyguanosine-5'-triphosphate (dGTP) from singlet oxygen provide either dSpTP or dGhTP at pH 8.0 or 4.4, respectively. Highly purified triphosphates are obtained by ion pair reversed-phase HPLC.
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Affiliation(s)
- Yu Ye
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
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Nakamura T, Kitaguchi Y, Miyazawa M, Kamiya H, Toma S, Ikemizu S, Shirakawa M, Nakabeppu Y, Yamagata Y. Crystallization and preliminary X-ray analysis of human MTH1 complexed with two oxidized nucleotides, 8-oxo-dGMP and 2-oxo-dATP. Acta Crystallogr Sect F Struct Biol Cryst Commun 2006; 62:1283-5. [PMID: 17142918 PMCID: PMC2225359 DOI: 10.1107/s1744309106049529] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2006] [Accepted: 11/19/2006] [Indexed: 11/10/2022]
Abstract
Human MutT homologue 1 (hMTH1) hydrolyzes a variety of oxidized purine nucleoside triphosphates, including 8-oxo-dGTP, 2-oxo-dATP, 2-oxo-ATP and 8-oxo-dATP, to their corresponding nucleoside monophosphates, while Escherichia coli MutT possesses prominent substrate specificity for 8-oxoguanine nucleotides. Three types of crystals were obtained corresponding to the following complexes: selenomethionine-labelled hMTH1 with 8-oxo-dGMP (SeMet hMTH1-8-oxo-dGMP), hMTH1 with 8-oxo-dGMP (hMTH1-8-oxo-dGMP) and hMTH1 with 2-oxo-dATP (hMTH1-2-oxo-dATP). Crystals of the SeMet hMTH1-8-oxo-dGMP complex belong to space group P4(1)2(1)2, with unit-cell parameters a = b = 45.8, c = 153.6 A, and diffracted to 2.90 A. Crystals of hMTH1-8-oxo-dGMP and hMTH1-2-oxo-dATP belong to space groups P2(1) and P2(1)2(1)2(1), with unit-cell parameters a = 34.0, b = 59.0, c = 65.9 A, beta = 90.7 degrees and a = 59.2, b = 67.3, c = 80.0 A, respectively. Their diffraction data were collected at resolutions of 1.95 and 2.22 A, respectively.
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Affiliation(s)
- Teruya Nakamura
- Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto 862-0973, Japan
| | - Yuki Kitaguchi
- Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto 862-0973, Japan
| | - Masayuki Miyazawa
- Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto 862-0973, Japan
| | - Hiroyuki Kamiya
- Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
| | - Sachiko Toma
- Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto 862-0973, Japan
| | - Shinji Ikemizu
- Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto 862-0973, Japan
| | | | - Yusaku Nakabeppu
- Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan
| | - Yuriko Yamagata
- Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto 862-0973, Japan
- Correspondence e-mail:
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Kamiya H, Cadena-Amaro C, Dugué L, Yakushiji H, Minakawa N, Matsuda A, Pochet S, Nakabeppu Y, Harashima H. Recognition of nucleotide analogs containing the 7,8-dihydro-8-oxo structure by the human MTH1 protein. J Biochem 2006; 140:843-9. [PMID: 17071637 DOI: 10.1093/jb/mvj214] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The MTH1 protein catalyzes hydrolysis of oxidatively damaged purine nucleotides including 8-hydroxy-dGTP to the monophosphates. The MTH1 protein seems to act as an important defense system against mutagenesis, carcinogenesis, and cell death induced by oxidized purine nucleotides. We previously reported that the functional groups at the 2- and 6-positions of the purine ring affect the recognition by the human MTH1 protein. 8-Hydroxy-dGTP and 8-hydroxy-dATP are substrates of MTH1, and both have the "7,8-dihydro-8-oxo structure." In this study, three nucleotide analogs containing this motif were examined. A synthetic purine analog containing the 7,8-dihydro-8-oxo structure and the 2-amino function (dJTP) was hydrolyzed to the monophosphate with high efficiency by MTH1. On the other hand, two analogs that lack the two-ring system of their bases [formamidopyrimidine-dGTP (FAPY-dGTP) and 2-OH-dYTP] were poor substrates. FAPY-dGTP is a mixture of conformers and was hydrolyzed more than ten-fold less efficiently than 8-hydroxy-dGTP. These results clarify the effects of the 2-amino group and the two-ring system of the purine base on the recognition by the human MTH1 protein.
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Affiliation(s)
- Hiroyuki Kamiya
- Faculty of Pharmaceutical Sciences, Hokkaido University, Kita-12, Nishi-6, Kita-ku, Sapporo 060-0812.
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Ing NH, Wolfskill RL, Clark S, DeGraauw JA, Gill CA. Steroid hormones acutely regulate expression of a Nudix protein-encoding gene in the endometrial epithelium of sheep. Mol Reprod Dev 2006; 73:967-76. [PMID: 16700076 DOI: 10.1002/mrd.20510] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Steroid hormones regulate endometrial gene expression to meet the needs of developing embryos. Our hypothesis is that steroid hormones transiently induce expression of genes in the endometrial epithelium to make the uterine environment different between the earliest days of pregnancy. We identified one such gene product using differential display-polymerase chain reactions. The gene product that was strongly induced in ewes between day 3 and 6 of the estrous cycle was cloned and sequenced to identify it as encoding a member of the Nudix family of hydrolase enzymes. Northern blot analyses indicated that NUDT16 mRNA concentrations were elevated 10-fold in the endometrium of sheep from day 5 to 9 of the estrous cycle and returned to basal levels by day 11. In assays of RNA samples from 15 different tissues from an adult ewe, the concentrations of NUDT16 mRNA were greatest in endometrium. In situ hybridization localized NUDT16 mRNA exclusively to the endometrial epithelial cells of the glands and uterine lumen. In ovariectomized ewes, NUDT16 mRNA was induced by a regimen of alternating estrogen and progesterone therapy designed to mimic the hormonal experiences of a ewe at day 6 of the estrous cycle. The final estrogen treatment in the regimen was critical to the expression of NUDT16 as well as progesterone receptor and estrogen receptor-beta genes. Characterization of the NUDT16 gene identified putative steroid hormone response elements, which can now be investigated to understand its unique pattern of regulation in the earliest days of pregnancy.
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Affiliation(s)
- Nancy H Ing
- Department of Animal Science, Center for Environmental and Rural Health, 2471 TAMU, Texas A&M University, College Station, 77843-2471, USA.
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Nakabeppu Y, Sakumi K, Sakamoto K, Tsuchimoto D, Tsuzuki T, Nakatsu Y. Mutagenesis and carcinogenesis caused by the oxidation of nucleic acids. Biol Chem 2006; 387:373-9. [PMID: 16606334 DOI: 10.1515/bc.2006.050] [Citation(s) in RCA: 173] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Genomes and their precursor nucleotides are highly exposed to reactive oxygen species, which are generated both as byproducts of oxygen respiration or molecular executors in the host defense, and by environmental exposure to ionizing radiation and chemicals. To counteract such oxidative damage in nucleic acids, mammalian cells are equipped with three distinct enzymes. MTH1 protein hydrolyzes oxidized purine nucleoside triphosphates, such as 8-oxo-2'-deoxyguanosine triphosphate and 2-hydroxy-2'-deoxyadenosine triphosphate (2-OH-dATP), to the corresponding monophosphates. We observed increased susceptibility to spontaneous carcinogenesis in MTH1-null mice, which exhibit an increased occurrence of A:T-->C:G and G:C-->T:A transversion mutations. 8-Oxoguanine (8-oxoG) DNA glycosylase, encoded by the OGG1 gene, and adenine DNA glycosylase, encoded by the MUTYH gene, are responsible for the suppression of G:C to T:A transversions caused by the accumulation of 8-oxoG in the genome. Deficiency of these enzymes leads to increased tumorigenesis in the lung and intestinal tract in mice, respectively. MUTYH deficiency may also increase G:C to T:A transversions through the misincorporation of 2-OH-dATP, especially in the intestinal tract, since MUTYH can excise 2-hydroxyadenine opposite guanine in genomic DNA and the repair activity is selectively impaired by a mutation found in patients with autosomal recessive colorectal adenomatous polyposis.
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Affiliation(s)
- Yusaku Nakabeppu
- Division of Neurofunctional Genomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-Ku, Fukuoka, 812-8582, Japan.
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Sakai Y, Oda H, Yoshimura D, Furuichi M, Kang D, Iwai S, Hara T, Nakabeppu Y. The GT to GC single nucleotide polymorphism at the beginning of an alternative exon 2C of human MTH1 gene confers an amino terminal extension that functions as a mitochondrial targeting signal. J Mol Med (Berl) 2006; 84:660-70. [PMID: 16607562 DOI: 10.1007/s00109-006-0053-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2006] [Accepted: 02/17/2006] [Indexed: 10/24/2022]
Abstract
Human MTH1 protein hydrolyzes oxidized purine nucleotides 8-oxo-2'-deoxyguanosine triphosphate (8-oxo-dGTP), 2-OH-dATP or their ribo-forms to their monophosphates, thus minimizing replicational and transcriptional errors both in the nuclei and mitochondria. MTH1 suppresses mitochondrial dysfunction and cell death caused by H(2)O(2). Furthermore, MTH1 suppresses the transient increase in 8-oxoguanine in mitochondrial DNA in the dopaminergic nerve terminals in mouse striatum after 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine administration, and it protects the nerve terminals. We previously reported that a novel MTH1 allele with a single nucleotide polymorphism (SNP) in its exon 2c segment encodes the fourth MTH1 isoform, namely, MTH1a (p26), in addition to the three known isoforms, MTH1b (p22), c (p21), and d (p18). Another SNP located in exon 4 of the MTH1 gene, which is closely linked to the SNP in exon 2c, substitutes the Val83 residue in MTH1d with Met83. We herein show that all MTH1 isoforms efficiently hydrolyzed 2-OH-dATP and 8-oxo-dGTP. The amino terminal region of MTH1a functioned as a mitochondrial targeting signal when it was expressed in the HeLa cells as a fusion protein with enhanced green fluorescent protein. The cellular fractionation revealed that MTH1a(Met83) was localized in the mitochondria to the same extent as was MTH1d(Val83). However, the mitochondrial translocation of MTH1d(Met83) was less efficient than that of MTH1d(Val83).
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Affiliation(s)
- Yasunari Sakai
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan
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Abstract
Cellular metabolism constantly generates by-products that are wasteful or even harmful. Such compounds are excreted from the cell or are removed through hydrolysis to normal cellular metabolites by various 'house-cleaning' enzymes. Some of the most important contaminants are non-canonical nucleoside triphosphates (NTPs) whose incorporation into the nascent DNA leads to increased mutagenesis and DNA damage. Enzymes intercepting abnormal NTPs from incorporation by DNA polymerases work in parallel with DNA repair enzymes that remove lesions produced by modified nucleotides. House-cleaning NTP pyrophosphatases targeting non-canonical NTPs belong to at least four structural superfamilies: MutT-related (Nudix) hydrolases, dUTPase, ITPase (Maf/HAM1) and all-alpha NTP pyrophosphatases (MazG). These enzymes have high affinity (Km's in the micromolar range) for their natural substrates (8-oxo-dGTP, dUTP, dITP, 2-oxo-dATP), which allows them to select these substrates from a mixture containing a approximately 1000-fold excess of canonical NTPs. To date, many house-cleaning NTPases have been identified only on the basis of their side activity towards canonical NTPs and NDP derivatives. Integration of growing structural and biochemical data on these superfamilies suggests that their new family members cleanse the nucleotide pool of the products of oxidative damage and inappropriate methylation. House-cleaning enzymes, such as 6-phosphogluconolactonase, are also part of normal intermediary metabolism. Genomic data suggest that house-cleaning systems are more abundant than previously thought and include numerous analogous enzymes with overlapping functions. We discuss the structural diversity of these enzymes, their phylogenetic distribution, substrate specificity and the problem of identifying their true substrates.
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Affiliation(s)
- Michael Y Galperin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA.
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Iida E, Satou K, Mishima M, Kojima C, Harashima H, Kamiya H. Amino acid residues involved in substrate recognition of the Escherichia coli Orf135 protein. Biochemistry 2005; 44:5683-9. [PMID: 15823026 DOI: 10.1021/bi048071o] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The Escherichia coli Orf135 protein, a MutT-type enzyme, hydrolyzes mutagenic 2-hydroxy-dATP (2-OH-dATP) and 8-hydroxy-dGTP, in addition to dCTP and 5-methyl-dCTP, and its deficiency causes increases in both the spontaneous and H(2)O(2)-induced mutation frequencies. To identify the amino acid residues that interact with these nucleotides, the Glu-33, Arg-72, Arg-77, and Asp-118 residues of Orf135, which are candidates for residues interacting with the base, were substituted, and the enzymatic activities of these mutant proteins were examined. The mutant proteins with a substitution at the 33rd, 72nd, and 118th amino acid residues displayed activities affected to various degrees for each substrate, suggesting the involvement of these residues in substrate binding. On the other hand, the mutant protein with a substitution at the 77th Arg residue had activitiy similar to that of the wild-type protein, excluding the possibility that this Arg side chain is involved in base recognition. In addition, the expression of some Orf135 mutants in orf135(-) E. coli reduced the level of formation of rpoB mutants elicited by H(2)O(2). These results reveal the residues involved in the substrate binding of the E. coli Orf135 protein.
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Affiliation(s)
- Emiko Iida
- Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-12, Nishi-6, Kita-ku, Sapporo 060-0812, Japan
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