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Kritsi E, Christodoulou P, Tsiaka T, Georgiadis P, Zervou M. A Computational Approach for the Discovery of Novel DNA Methyltransferase Inhibitors. Curr Issues Mol Biol 2024; 46:3394-3407. [PMID: 38666943 PMCID: PMC11049320 DOI: 10.3390/cimb46040213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 04/11/2024] [Accepted: 04/13/2024] [Indexed: 04/28/2024] Open
Abstract
Nowadays, the explosion of knowledge in the field of epigenetics has revealed new pathways toward the treatment of multifactorial diseases, rendering the key players of the epigenetic machinery the focus of today's pharmaceutical landscape. Among epigenetic enzymes, DNA methyltransferases (DNMTs) are first studied as inhibition targets for cancer treatment. The increasing clinical interest in DNMTs has led to advanced experimental and computational strategies in the search for novel DNMT inhibitors. Considering the importance of epigenetic targets as a novel and promising pharmaceutical trend, the present study attempted to discover novel inhibitors of natural origin against DNMTs using a combination of structure and ligand-based computational approaches. Particularly, a pharmacophore-based virtual screening was performed, followed by molecular docking and molecular dynamics simulations in order to establish an accurate and robust selection methodology. Our screening protocol prioritized five natural-derived compounds, derivatives of coumarins, flavones, chalcones, benzoic acids, and phenazine, bearing completely diverse chemical scaffolds from FDA-approved "Epi-drugs". Their total DNMT inhibitory activity was evaluated, revealing promising results for the derived hits with an inhibitory activity ranging within 30-45% at 100 µM of the tested compounds.
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Affiliation(s)
- Eftichia Kritsi
- Institute of Chemical Biology, National Hellenic Research Foundation, 48 Vassileos Constantinou Avenue, 11635 Athens, Greece; (P.C.); (T.T.); (P.G.)
| | | | | | | | - Maria Zervou
- Institute of Chemical Biology, National Hellenic Research Foundation, 48 Vassileos Constantinou Avenue, 11635 Athens, Greece; (P.C.); (T.T.); (P.G.)
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2
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Kadam MS, Burra VLSP. S-adenosyl-l-methionine interaction signatures in methyltransferases. J Biomol Struct Dyn 2024; 42:3166-3176. [PMID: 37261836 DOI: 10.1080/07391102.2023.2217679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 05/01/2023] [Indexed: 06/02/2023]
Abstract
The switching on or off of methylation, a change from a normal methylation to hyper or hypo methylation is implicated in many diseases that include cancers, infectious, neurodegenerative diseases and others. Methyltransferases are one of the most sought targets that have diversified for the methylation of a variety of substrates. However, without S-adenosyl-l-methionine (SAM), the universal methyl donor, the majority of the methyltransferases remain functionally inactive. In this article, we did a comprehensive analysis of all available SAM-receptor crystal structures at atom, moiety and structure levels to gain deeper insights into the structure and function of SAM. SAM demonstrated flexibility in binding to a variety of receptors irrespective of the size of the binding pockets. Further analysis of the binding pockets resulted in all SAM conformations clustering into four natural shapes. The conserved interaction analysis provides an unambiguous orientation of SAM binding to receptors which has been elusive till now. SAM peptide moiety (SPM) and SAM nucleobase moiety (SNM) show up to 89% interactions with receptors whereas only 11% interactions with SAM ribose moiety (SRM). It is found that SPM and SNM terminal atoms anchor to the highly conserved receptor subsites creating a workbench for catalysis. It is seen that every interacting atom and its position is crucial in the methyl transfer phenomenon. A very unique observation is that the methyl group of SAM does not have even one interaction with the receptor. The deep insights gained help in the design and development of novel drugs against the methyltransferases.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Mangal S Kadam
- Center for Advanced Research and Innovation in Structural Biology of Diseases (CARISBD), Department of Biotechnology, KLEF University, Vaddeswaram, Andhra Pradesh, India
| | - V L S Prasad Burra
- Center for Advanced Research and Innovation in Structural Biology of Diseases (CARISBD), Department of Biotechnology, KLEF University, Vaddeswaram, Andhra Pradesh, India
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Gade M, Gardner JM, Jain P, Laurino P. Nucleoside-Driven Specificity of DNA Methyltransferase. Chembiochem 2023; 24:e202300094. [PMID: 37548117 DOI: 10.1002/cbic.202300094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Revised: 08/03/2023] [Accepted: 08/05/2023] [Indexed: 08/08/2023]
Abstract
We have studied the adenosine binding specificities of two bacterial DNA methyltransferases, Taq methyltransferase (M.TaqI), and HhaI methyltransferase (M.HhaI). While they have similar cofactor binding pocket interactions, experimental data showed different specificity for novel S-nucleobase-l-methionine cofactors (SNMs; N=guanosyl, cytidyl, uridyl). Protein dynamics corroborate the experimental data on the cofactor specificities. For M.TaqI the specificity for S-adenosyl-l-methionine (SAM) is governed by the tight binding on the nucleoside part of the cofactor, while for M.HhaI the degree of freedom of the nucleoside chain allows the acceptance of other bases. The experimental data prove catalytically productive methylation by the M.HhaI binding pocket for all the SNMs. Our results suggest a new route for successful design of unnatural SNM analogues for methyltransferases as a tool for cofactor engineering.
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Affiliation(s)
- Madhuri Gade
- Protein Engineering and Evolution Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna, Okinawa, 904-0495, Japan
| | - Jasmine M Gardner
- Department of Chemistry - BMC, Uppsala University, Box 576, 751 23, Uppsala, Sweden
| | - Prashant Jain
- Protein Engineering and Evolution Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna, Okinawa, 904-0495, Japan
| | - Paola Laurino
- Protein Engineering and Evolution Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna, Okinawa, 904-0495, Japan
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4
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Nayak A, Chavarria A, Sanders KN, Ghalei H, Khoshnevis S. Sinefungin, a natural nucleoside analog of S-adenosyl methionine, impairs the pathogenicity of Candida albicans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.12.562127. [PMID: 37873365 PMCID: PMC10592816 DOI: 10.1101/2023.10.12.562127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Candida albicans, an opportunistic fungal human pathogen, is a major threat to the healthcare system due to both infections in immunocompromised individuals and the emergence of antifungal resistance. Fungal infection caused by C. albicans, candidiasis, is a life-threatening condition in immunocompromised patients and the current treatments are mostly restricted to polyenes, azoles, and echinocandins. Use of these antifungals is limited by toxicity, drug-drug interactions, and the emergence of resistance, underscoring the importance of identifying novel therapeutic targets and the need for new treatment approaches. C. albicans can undergo a morphological transition from yeast to hyphae and this transition is central to C. albicans virulence. Here, we determine the impact of sinefungin, a natural nucleoside analog of S-adenosyl methionine, on the virulence of C. albicans strain SC5314 by evaluating treatment effects on the morphological transition, human epithelial cell adhesion, and biofilm formation. Our data indicate that sinefungin impairs pathogenic traits of C. albicans including hyphal lengthening, biofilm formation and the adhesion to the human epithelial cell lines, without adversely affecting human cells, therefore highlighting sinefungin as a potential avenue for therapeutic intervention. We determine that the formation of N6-methyladenosine (m6A) is particularly disturbed by sinefungin. More broadly, this study underscores the importance of considering the post-transcriptional control mechanisms of pathogenicity when designing therapeutic solutions to fungal infection.
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Affiliation(s)
- Anushka Nayak
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA
| | - Alejandro Chavarria
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA
| | - Kyla N. Sanders
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA
| | - Homa Ghalei
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA
| | - Sohail Khoshnevis
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA
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5
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Zhou J, Horton JR, Yu D, Ren R, Blumenthal RM, Zhang X, Cheng X. Repurposing epigenetic inhibitors to target the Clostridioides difficile-specific DNA adenine methyltransferase and sporulation regulator CamA. Epigenetics 2021; 17:970-981. [PMID: 34523387 PMCID: PMC9487755 DOI: 10.1080/15592294.2021.1976910] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Epigenetically targeted therapeutic development, particularly for SAM-dependent methylations of DNA, mRNA and histones has been proceeding rapidly for cancer treatments over the past few years. However, this approach has barely begun to be exploited for developing new antibiotics, despite an overwhelming global need to counter antimicrobial resistance. Here, we explore whether SAM analogues, some of which are in (pre)clinical studies as inhibitors of human epigenetic enzymes, can also inhibit Clostridioides difficile-specific DNA adenine methyltransferase (CamA), a sporulation regulator present in all C. difficile genomes sequenced to date, but found in almost no other bacteria. We found that SGC0946 (an inhibitor of DOT1L), JNJ-64619178 (an inhibitor of PRMT5) and SGC8158 (an inhibitor of PRMT7) inhibit CamA enzymatic activity in vitro at low micromolar concentrations. Structural investigation of the ternary complexes of CamA-DNA in the presence of SGC0946 or SGC8158 revealed conformational rearrangements of the N-terminal arm, with no apparent disturbance of the active site. This N-terminal arm and its modulation of exchanges between SAM (the methyl donor) and SAH (the reaction product) during catalysis of methyl transfer are, to date, unique to CamA. Our work presents a substantial first step in generating potent and selective inhibitors of CamA that would serve in the near term as chemical probes to investigate the cellular mechanism(s) of CamA in controlling spore formation and colonization, and eventually as therapeutic antivirulence agents useful in treating C. difficile infection.
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Affiliation(s)
- Jujun Zhou
- Department of Epigenetics and Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - John R Horton
- Department of Epigenetics and Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Dan Yu
- Department of Epigenetics and Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Ren Ren
- Department of Epigenetics and Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Robert M Blumenthal
- Department of Medical Microbiology and Immunology, and Program in Bioinformatics, The University of Toledo College of Medicine and Life Sciences, Toledo, OH USA
| | - Xing Zhang
- Department of Epigenetics and Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Xiaodong Cheng
- Department of Epigenetics and Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Houston, TX, USA
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6
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Zhou J, Horton JR, Blumenthal RM, Zhang X, Cheng X. Clostridioides difficile specific DNA adenine methyltransferase CamA squeezes and flips adenine out of DNA helix. Nat Commun 2021; 12:3436. [PMID: 34103525 PMCID: PMC8187626 DOI: 10.1038/s41467-021-23693-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 05/13/2021] [Indexed: 12/13/2022] Open
Abstract
Clostridioides difficile infections are an urgent medical problem. The newly discovered C. difficile adenine methyltransferase A (CamA) is specified by all C. difficile genomes sequenced to date (>300), but is rare among other bacteria. CamA is an orphan methyltransferase, unassociated with a restriction endonuclease. CamA-mediated methylation at CAAAAA is required for normal sporulation, biofilm formation, and intestinal colonization by C. difficile. We characterized CamA kinetic parameters, and determined its structure bound to DNA containing the recognition sequence. CamA contains an N-terminal domain for catalyzing methyl transfer, and a C-terminal DNA recognition domain. Major and minor groove DNA contacts in the recognition site involve base-specific hydrogen bonds, van der Waals contacts and the Watson-Crick pairing of a rearranged A:T base pair. These provide sufficient sequence discrimination to ensure high specificity. Finally, the surprisingly weak binding of the methyl donor S-adenosyl-L-methionine (SAM) might provide avenues for inhibiting CamA activity using SAM analogs.
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Affiliation(s)
- Jujun Zhou
- Department of Epigenetics and Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - John R Horton
- Department of Epigenetics and Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Robert M Blumenthal
- Department of Medical Microbiology and Immunology, and Program in Bioinformatics, The University of Toledo College of Medicine and Life Sciences, Toledo, OH, USA
| | - Xing Zhang
- Department of Epigenetics and Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Houston, TX, USA.
| | - Xiaodong Cheng
- Department of Epigenetics and Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Houston, TX, USA.
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7
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Long Y, Ubych K, Jagu E, Neely RK. FRET-Based Method for Direct, Real-Time Measurement of DNA Methyltransferase Activity. Bioconjug Chem 2020; 32:192-198. [PMID: 33306345 DOI: 10.1021/acs.bioconjchem.0c00612] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
DNA methyltransferase activity is associated with a host of diseases, including cancers, where global hypomethylation of the genome, as well as marked changes in local DNA methylation patterns, can be both diagnostic and prognostic for the disease. Despite this, we currently lack a method for directly measuring the activity of the DNA methyltransferases, which would support the development of DNA methyltransferase-targeted therapies. Here, we demonstrate an assay for the direct measurement of methyltransferase activity, in real time. We employ a fluorescent methyltransferase cofactor analogue, which when bound by the enzyme to a labeled target DNA sequence results in fluorescence resonance energy transfer (FRET) between the donor dye (DNA) and the acceptor dye (cofactor). We demonstrate that the method can be used to monitor the activity of DNA MTases in real time and can be applied to screen inhibitors of the DNA methyltransferases. We show this in both bulk phase and single molecule imaging experiments, highlighting the potential application of the assay in screening and biophysical studies of methyltransferase function.
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Affiliation(s)
- Yi Long
- The University of Birmingham, School of Chemistry, Edgbaston, Birmingham, B15 2TT, United Kingdom.,Medical Research Center, Southern University of Science and Technology Hospital, Shenzhen, Guangdong Province, 518055, China
| | - Krystian Ubych
- The University of Birmingham, School of Chemistry, Edgbaston, Birmingham, B15 2TT, United Kingdom
| | - Elodie Jagu
- The University of Birmingham, School of Chemistry, Edgbaston, Birmingham, B15 2TT, United Kingdom.,ICCF, SIGMA Clermont, Université Clermont Auvergne, CNRS, Clermont-Ferrand, 63178 Aubière, France
| | - Robert K Neely
- The University of Birmingham, School of Chemistry, Edgbaston, Birmingham, B15 2TT, United Kingdom
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8
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The conserved aspartate in motif III of β family AdoMet-dependent DNA methyltransferase is important for methylation. J Biosci 2020. [DOI: 10.1007/s12038-019-9983-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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9
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Peinado RDS, Olivier DS, Eberle RJ, de Moraes FR, Amaral MS, Arni RK, Coronado MA. Binding studies of a putative C. pseudotuberculosis target protein from Vitamin B 12 Metabolism. Sci Rep 2019; 9:6350. [PMID: 31015525 PMCID: PMC6478909 DOI: 10.1038/s41598-019-42935-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 03/13/2019] [Indexed: 01/20/2023] Open
Abstract
Vitamin B12 acts as a cofactor for various metabolic reactions important in living organisms. The Vitamin B12 biosynthesis is restricted to prokaryotes, which means, all eukaryotic organisms must acquire this molecule through diet. This study presents the investigation of Vitamin B12 metabolism and the characterization of precorrin-4 C(11)-methyltransferase (CobM), an enzyme involved in the biosynthesis of Vitamin B12 in Corynebacterium pseudotuberculosis. The analysis of the C. pseudotuberculosis genome identified two Vitamin B12-dependent pathways, which can be strongly affected by a disrupted vitamin metabolism. Molecular dynamics, circular dichroism, and NMR-STD experiments identified regions in CobM that undergo conformational changes after s-adenosyl-L-methionine binding to promote the interaction of precorrin-4, a Vitamin B12 precursor. The binding of s-adenosyl-L-methionine was examined along with the competitive binding of adenine, dATP, and suramin. Based on fluorescence spectroscopy experiments the dissociation constant for the four ligands and the target protein could be determined; SAM (1.4 ± 0.7 µM), adenine (17.8 ± 1.5 µM), dATP (15.8 ± 2.0 µM), and Suramin (6.3 ± 1.1 µM). The results provide rich information for future investigations of potential drug targets within the C. pseudotuberculosis's Vitamin B12 metabolism and related pathways to reduce the pathogen's virulence in its hosts.
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Affiliation(s)
- Rafaela Dos S Peinado
- Multiuser Center for Biomolecular Innovation, Departament of Physics, Instituto de Biociências Letras e Ciências Exatas (Ibilce), Universidade Estadual Paulista (UNESP), São Jose do Rio Preto-SP, 15054-000, Brazil
| | - Danilo S Olivier
- Multiuser Center for Biomolecular Innovation, Departament of Physics, Instituto de Biociências Letras e Ciências Exatas (Ibilce), Universidade Estadual Paulista (UNESP), São Jose do Rio Preto-SP, 15054-000, Brazil
| | - Raphael J Eberle
- Multiuser Center for Biomolecular Innovation, Departament of Physics, Instituto de Biociências Letras e Ciências Exatas (Ibilce), Universidade Estadual Paulista (UNESP), São Jose do Rio Preto-SP, 15054-000, Brazil
| | - Fabio R de Moraes
- Multiuser Center for Biomolecular Innovation, Departament of Physics, Instituto de Biociências Letras e Ciências Exatas (Ibilce), Universidade Estadual Paulista (UNESP), São Jose do Rio Preto-SP, 15054-000, Brazil
| | - Marcos S Amaral
- Institute of Physics, Federal University of Mato Grosso do Sul, Campo Grande, MS, 79090-700, Brazil
| | - Raghuvir K Arni
- Multiuser Center for Biomolecular Innovation, Departament of Physics, Instituto de Biociências Letras e Ciências Exatas (Ibilce), Universidade Estadual Paulista (UNESP), São Jose do Rio Preto-SP, 15054-000, Brazil.
| | - Monika A Coronado
- Multiuser Center for Biomolecular Innovation, Departament of Physics, Instituto de Biociências Letras e Ciências Exatas (Ibilce), Universidade Estadual Paulista (UNESP), São Jose do Rio Preto-SP, 15054-000, Brazil.
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Lascano S, Lopez M, Arimondo PB. Natural Products and Chemical Biology Tools: Alternatives to Target Epigenetic Mechanisms in Cancers. CHEM REC 2018; 18:1854-1876. [PMID: 30537358 DOI: 10.1002/tcr.201800133] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 11/05/2018] [Accepted: 11/05/2018] [Indexed: 12/21/2022]
Abstract
DNA methylation and histone acetylation are widely studied epigenetic modifications. They are involved in numerous pathologies such as cancer, neurological disease, inflammation, obesity, etc. Since the discovery of the epigenome, numerous compounds have been developed to reverse DNA methylation and histone acetylation aberrant profile in diseases. Among them several were inspired by Nature and have a great interest as therapeutic molecules. In the quest of finding new ways to target epigenetic mechanisms, the use of chemical tools is a powerful strategy to better understand epigenetic mechanisms in biological systems. In this review we will present natural products reported as DNMT or HDAC inhibitors for anticancer treatments. We will then discuss the use of chemical tools that have been used in order to explore the epigenome.
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Affiliation(s)
- Santiago Lascano
- Institut des Biomolécules Max Mousseron (IBMM), UMR 5247 CNRS-Université de Montpellier-ENSCM, 240 avenue du Prof. E. Jeanbrau, 34296, Montpellier cedex 5, France
| | - Marie Lopez
- Institut des Biomolécules Max Mousseron (IBMM), UMR 5247 CNRS-Université de Montpellier-ENSCM, 240 avenue du Prof. E. Jeanbrau, 34296, Montpellier cedex 5, France
| | - Paola B Arimondo
- Epigenetic Chemical Biology, Institut Pasteur, CNRS UMR3523, 28 rue du Docteur Roux, 75724, Paris cedex 15, France
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Blaschke U, Suwono B, Zafari S, Ebersberger I, Skiebe E, Jeffries CM, Svergun DI, Wilharm G. Recombinant production of A1S_0222 from Acinetobacter baumannii ATCC 17978 and confirmation of its DNA-(adenine N6)-methyltransferase activity. Protein Expr Purif 2018; 151:78-85. [DOI: 10.1016/j.pep.2018.06.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 06/07/2018] [Accepted: 06/13/2018] [Indexed: 11/16/2022]
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12
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Kinetic Basis of the Bifunctionality of SsoII DNA Methyltransferase. Molecules 2018; 23:molecules23051192. [PMID: 29772716 PMCID: PMC6100179 DOI: 10.3390/molecules23051192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 05/04/2018] [Accepted: 05/08/2018] [Indexed: 12/04/2022] Open
Abstract
Type II restriction–modification (RM) systems are the most widespread bacterial antiviral defence mechanisms. DNA methyltransferase SsoII (M.SsoII) from a Type II RM system SsoII regulates transcription in its own RM system in addition to the methylation function. DNA with a so-called regulatory site inhibits the M.SsoII methylation activity. Using circular permutation assay, we show that M.SsoII monomer induces DNA bending of 31° at the methylation site and 46° at the regulatory site. In the M.SsoII dimer bound to the regulatory site, both protein subunits make equal contributions to the DNA bending, and both angles are in the same plane. Fluorescence of TAMRA, 2-aminopurine, and Trp was used to monitor conformational dynamics of DNA and M.SsoII under pre-steady-state conditions by stopped-flow technique. Kinetic data indicate that M.SsoII prefers the regulatory site to the methylation site at the step of initial protein–DNA complex formation. Nevertheless, in the presence of S-adenosyl-l-methionine, the induced fit is accelerated in the M.SsoII complex with the methylation site, ensuring efficient formation of the catalytically competent complex. The presence of S-adenosyl-l-methionine and large amount of the methylation sites promote efficient DNA methylation by M.SsoII despite the inhibitory effect of the regulatory site.
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13
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Singh S, Guruprasad L. N6-Adenosine DNA Methyltransferase from H. pylori 98-10 Strain in Complex with DNA and AdoMet: Structural Insights from in Silico Studies. J Phys Chem B 2017; 121:365-378. [PMID: 28054779 DOI: 10.1021/acs.jpcb.6b08433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Helicobacter pylori is a primitive Gram-negative bacterium that resides in the acidic environment of the human gastrointestinal tract, and some strains of this bacterium cause gastric ulcers and cancer. DNA methyltransferases (MTases) are promising drug targets for the treatment of cancer and other diseases that are also caused by epigenetic alternations of the genome. The N6-adenine-specific DNA MTase from H. pylori (M. Hpy N6mA) catalyzes the transfer of a methyl group from the cofactor S-adenosyl-l-methionine (AdoMet) to the flipped adenine of the substrate DNA. In this work, we report the sequence analyses, three-dimensional structure modeling, and molecular dynamics simulations of M. Hpy N6mA, when complexed with AdoMet as well as DNA. We analyzed the protein-DNA interactions prominently established by the flipped cytosine and the interactions between protein cofactors in the active site. The comparable orientation of AdoMet in both systems confirms that AdoMet is in a catalytically competent orientation in the bimolecular system that is retained upon DNA binding in the termolecular system of M. Hpy N6mA. In both systems, AdoMet is stabilized in the binding pocket by hydrogen bonding (Thr84, Glu99, Asp122, and Phe123) as well as van der Waals (Ile100, Phe160, Arg104, and Cys76) interactions. We propose that the contacts made by flipped adenine DA6 with Asn138 (N6 and N1 atom of DA6) and Pro139 (N6) and π-stacking interactions with Phe141 and Phe219 play an important role in the methylation mechanism at the N6 position in our N6mA model. Specific recognition of DNA is mediated by residues 143-155, 183-189, 212-220, 280-293, and 308-325. These findings are further supported by alanine scanning mutagenesis studies. The conserved residues in distantly related sequences of the small domain are important in DNA binding. Results reported here elucidate the sequence, structure, and binding features necessary for the recognition between cofactor AdoMet and substrate DNA by the vital epigenetic enzyme, M. Hpy N6mA.
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Affiliation(s)
- Swati Singh
- School of Chemistry, University of Hyderabad , Hyderabad 500046, India
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14
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Khan I, Senthilkumar CS, Upadhyay N, Singh H, Sachdeva M, Jatawa SK, Tiwari A. In silico docking of methyl isocyanate (MIC) and its hydrolytic product (1, 3-dimethylurea) shows significant interaction with DNA Methyltransferase 1 suggests cancer risk in Bhopal-Gas- Tragedy survivors. Asian Pac J Cancer Prev 2016; 16:7663-70. [PMID: 26625778 DOI: 10.7314/apjcp.2015.16.17.7663] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
DNA methyltransferase 1 (DNMT1) is a relatively large protein family responsible for maintenance of normal methylation, cell growth and survival in mammals. Toxic industrial chemical exposure associated methylation misregulation has been shown to have epigenetic influence. Such misregulation could effectively contribute to cancer development and progression. Methyl isocyanate (MIC) is a noxious industrial chemical used extensively in the production of carbamate pesticides. We here applied an in silico molecular docking approach to study the interaction of MIC with diverse domains of DNMT1, to predict cancer risk in the Bhopal population exposed to MIC during 1984. For the first time, we investigated the interaction of MIC and its hydrolytic product (1,3-dimethylurea) with DNMT1 interacting (such as DMAP1, RFTS, and CXXC) and catalytic (SAM, SAH, and Sinefungin) domains using computer simulations. The results of the present study showed a potential interaction of MIC and 1,3-dimethylurea with these domains. Obviously, strong binding of MIC with DNMT1 interrupting normal methylation will lead to epigenetic alterations in the exposed humans. We suggest therefore that the MIC- exposed individuals surviving after 1984 disaster have excess risk of cancer, which can be attributed to alterations in their epigenome. Our findings will help in better understanding the underlying epigenetic mechanisms in humans exposed to MIC.
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Affiliation(s)
- Inbesat Khan
- School of Biotechnology, Rajiv Gandhi Technological University, Bhopal, India E-mail :
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15
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Hirata A, Nishiyama S, Tamura T, Yamauchi A, Hori H. Structural and functional analyses of the archaeal tRNA m2G/m22G10 methyltransferase aTrm11 provide mechanistic insights into site specificity of a tRNA methyltransferase that contains common RNA-binding modules. Nucleic Acids Res 2016; 44:6377-90. [PMID: 27325738 PMCID: PMC5291279 DOI: 10.1093/nar/gkw561] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 06/09/2016] [Indexed: 12/30/2022] Open
Abstract
N(2)-methylguanosine is one of the most universal modified nucleosides required for proper function in transfer RNA (tRNA) molecules. In archaeal tRNA species, a specific S-adenosyl-L-methionine (SAM)-dependent tRNA methyltransferase (MTase), aTrm11, catalyzes formation of N(2)-methylguanosine and N(2),N(2)-dimethylguanosine at position 10. Here, we report the first X-ray crystal structures of aTrm11 from Thermococcus kodakarensis (Tko), of the apo-form, and of its complex with SAM. The structures show that TkoTrm11 consists of three domains: an N-terminal ferredoxinlike domain (NFLD), THUMP domain and Rossmann-fold MTase (RFM) domain. A linker region connects the THUMP-NFLD and RFM domains. One SAM molecule is bound in the pocket of the RFM domain, suggesting that TkoTrm11 uses a catalytic mechanism similar to that of other tRNA MTases containing an RFM domain. Furthermore, the conformation of NFLD and THUMP domains in TkoTrm11 resembles that of other tRNA-modifying enzymes specifically recognizing the tRNA acceptor stem. Our docking model of TkoTrm11-SAM in complex with tRNA, combined with biochemical analyses and pre-existing evidence, provides insights into the substrate tRNA recognition mechanism: The THUMP domain recognizes a 3'-ACCA end, and the linker region and RFM domain recognize the T-stem, acceptor stem and V-loop of tRNA, thereby causing TkoTrm11 to specifically identify its methylation site.
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Affiliation(s)
- Akira Hirata
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
| | - Seiji Nishiyama
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
| | - Toshihiro Tamura
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
| | - Ayano Yamauchi
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
| | - Hiroyuki Hori
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
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16
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Callahan SJ, Luyten YA, Gupta YK, Wilson GG, Roberts RJ, Morgan RD, Aggarwal AK. Structure of Type IIL Restriction-Modification Enzyme MmeI in Complex with DNA Has Implications for Engineering New Specificities. PLoS Biol 2016; 14:e1002442. [PMID: 27082731 PMCID: PMC4833311 DOI: 10.1371/journal.pbio.1002442] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 03/17/2016] [Indexed: 01/18/2023] Open
Abstract
The creation of restriction enzymes with programmable DNA-binding and -cleavage specificities has long been a goal of modern biology. The recently discovered Type IIL MmeI family of restriction-and-modification (RM) enzymes that possess a shared target recognition domain provides a framework for engineering such new specificities. However, a lack of structural information on Type IIL enzymes has limited the repertoire that can be rationally engineered. We report here a crystal structure of MmeI in complex with its DNA substrate and an S-adenosylmethionine analog (Sinefungin). The structure uncovers for the first time the interactions that underlie MmeI-DNA recognition and methylation (5’-TCCRAC-3’; R = purine) and provides a molecular basis for changing specificity at four of the six base pairs of the recognition sequence (5’-TCCRAC-3’). Surprisingly, the enzyme is resilient to specificity changes at the first position of the recognition sequence (5’-TCCRAC-3’). Collectively, the structure provides a basis for engineering further derivatives of MmeI and delineates which base pairs of the recognition sequence are more amenable to alterations than others. The structure of the bifunctional Type IIL restriction-and-modification enzyme MmeI provides a basis for understanding how such enzymes recognize their substrates and a framework for manipulating their specificities. Type II restriction endonucleases (REases) are the bedrock of modern biotechnology. Type II REases were essential for the recombinant DNA revolution and the development of gene technology. However, despite the discovery of more than 4,000 REases, the DNA recognition specificities are limited to only ~365. The recently discovered Type IIL MmeI family of restriction-and-modification (RM) enzymes provides a framework for understanding and engineering new specificities. We report here a crystal structure of MmeI in complex with its DNA substrate and an S-adenosylmethionine analog (Sinefungin). The structure uncovers for the first time the interactions that underlie MmeI-DNA recognition and methylation. The results establish a platform for rationally engineering further derivatives from MmeI and its homologs that will possess new, intentionally chosen, specificities.
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Affiliation(s)
- Scott J. Callahan
- Department of Structural and Chemical Biology, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Yvette A. Luyten
- New England Biolabs Inc., Ipswich, Massachusetts, United States of America
| | - Yogesh K. Gupta
- Department of Structural and Chemical Biology, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Geoffrey G. Wilson
- New England Biolabs Inc., Ipswich, Massachusetts, United States of America
| | - Richard J. Roberts
- New England Biolabs Inc., Ipswich, Massachusetts, United States of America
| | - Richard D. Morgan
- New England Biolabs Inc., Ipswich, Massachusetts, United States of America
- * E-mail: (RDM); (AKA)
| | - Aneel K. Aggarwal
- Department of Structural and Chemical Biology, Mount Sinai School of Medicine, New York, New York, United States of America
- * E-mail: (RDM); (AKA)
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17
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Maier JAH, Albu RF, Jurkowski TP, Jeltsch A. Investigation of the C-terminal domain of the bacterial DNA-(adenine N6)-methyltransferase CcrM. Biochimie 2015; 119:60-7. [PMID: 26475175 DOI: 10.1016/j.biochi.2015.10.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 10/11/2015] [Indexed: 01/30/2023]
Abstract
CcrM-related DNA-(adenine N6)-methyltransferases play very important roles in the biology of Caulobacter crescentus and other alpha-proteobacteria. These enzymes methylate GANTC sequences, but the molecular mechanism by which they recognize their target sequence is unknown. We carried out multiple sequence alignments and noticed that CcrM enzymes contain a conserved C-terminal domain (CTD) which is not present in other DNA-(adenine N6)-methyltransferases and we show here that deletion of this part abrogates catalytic activity and DNA binding of CcrM. A mutational study identified 7 conserved residues in the CTD (out of 13 tested), mutation of which led to a strong reduction in catalytic activity. All of these mutants showed altered DNA binding, but no change in AdoMet binding and secondary structure. Some mutants exhibited reduced DNA binding, but others showed an enhanced DNA binding. Moreover, we show that CcrM does not specifically bind to DNA containing GANTC sequences. Taken together, these findings suggest that the specific CcrM-DNA complex undergoes a conformational change, which is endergonic but essential for catalytic activity and this step is blocked by some of the mutations. Moreover, our data indicate that the CTD of CcrM is involved in DNA binding and recognition. This suggests that the CTD functions as target recognition domain of CcrM and, therefore, CcrM can be considered the first example of a δ-type DNA-(adenine N6)-methyltransferase identified so far.
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Affiliation(s)
- Johannes A H Maier
- Institute of Biochemistry, Stuttgart University, 70569 Stuttgart, Germany
| | - Razvan F Albu
- Institute of Biochemistry, Stuttgart University, 70569 Stuttgart, Germany
| | - Tomasz P Jurkowski
- Institute of Biochemistry, Stuttgart University, 70569 Stuttgart, Germany
| | - Albert Jeltsch
- Institute of Biochemistry, Stuttgart University, 70569 Stuttgart, Germany.
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18
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Dong H, Xu W, Pillai JK, Packianathan C, Rosen BP. High-throughput screening-compatible assays of As(III) S-adenosylmethionine methyltransferase activity. Anal Biochem 2015; 480:67-73. [PMID: 25866076 DOI: 10.1016/j.ab.2015.04.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2015] [Revised: 04/03/2015] [Accepted: 04/06/2015] [Indexed: 11/18/2022]
Abstract
Arsenic is a naturally existing toxin and carcinogen. As(III) S-adenosylmethionine methyltransferases (AS3MT in mammals and ArsM in microbes) methylate As(III) three times in consecutive steps and play a central role in arsenic metabolism from bacteria to humans. Current assays for arsenic methylation are slow, laborious, and expensive. Here we report the development of two in vitro assays for AS3MT activity that are rapid, sensitive, convenient, and relatively inexpensive and can be adapted for high-throughput assays. The first assay measures As(III) binding by the quenching of the protein fluorescence of a single-tryptophan derivative of an AS3MT ortholog. The second assay utilizes time-resolved fluorescence resonance energy transfer to directly measure the conversion of the AS3MT substrate, S-adenosylmethionine, to S-adenosylhomocysteine catalyzed by AS3MT. These two assays are complementary, one measuring substrate binding and the other catalysis, making them useful tools for functional studies and future development of drugs to prevent arsenic-related diseases.
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Affiliation(s)
- Hui Dong
- Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, FL 33199, USA
| | - Wenzhong Xu
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Jitesh K Pillai
- Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, FL 33199, USA
| | - Charles Packianathan
- Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, FL 33199, USA
| | - Barry P Rosen
- Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, FL 33199, USA.
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19
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Aranda J, Zinovjev K, Roca M, Tuñón I. Dynamics and Reactivity in Thermus aquaticus N6-Adenine Methyltransferase. J Am Chem Soc 2014; 136:16227-39. [DOI: 10.1021/ja5077124] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Juan Aranda
- Departament de Química
Física, Universitat de València, 46100 Burjassot, Spain
| | - Kirill Zinovjev
- Departament de Química
Física, Universitat de València, 46100 Burjassot, Spain
| | - Maite Roca
- Departament de Química
Física, Universitat de València, 46100 Burjassot, Spain
| | - Iñaki Tuñón
- Departament de Química
Física, Universitat de València, 46100 Burjassot, Spain
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20
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Kimura S, Miyauchi K, Ikeuchi Y, Thiaville PC, Crécy-Lagard VD, Suzuki T. Discovery of the β-barrel-type RNA methyltransferase responsible for N6-methylation of N6-threonylcarbamoyladenosine in tRNAs. Nucleic Acids Res 2014; 42:9350-65. [PMID: 25063302 PMCID: PMC4132733 DOI: 10.1093/nar/gku618] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Methylation is a versatile reaction involved in the synthesis and modification of biologically active molecules, including RNAs. N(6)-methyl-threonylcarbamoyl adenosine (m(6)t(6)A) is a post-transcriptional modification found at position 37 of tRNAs from bacteria, insect, plants, and mammals. Here, we report that in Escherichia coli, yaeB (renamed as trmO) encodes a tRNA methyltransferase responsible for the N(6)-methyl group of m(6)t(6)A in tRNA(Thr) specific for ACY codons. TrmO has a unique single-sheeted β-barrel structure and does not belong to any known classes of methyltransferases. Recombinant TrmO employs S-adenosyl-L-methionine (AdoMet) as a methyl donor to methylate t(6)A to form m(6)t(6)A in tRNA(Thr). Therefore, TrmO/YaeB represents a novel category of AdoMet-dependent methyltransferase (Class VIII). In a ΔtrmO strain, m(6)t(6)A was converted to cyclic t(6)A (ct(6)A), suggesting that t(6)A is a common precursor for both m(6)t(6)A and ct(6)A. Furthermore, N(6)-methylation of t(6)A enhanced the attenuation activity of the thr operon, suggesting that TrmO ensures efficient decoding of ACY. We also identified a human homolog, TRMO, indicating that m(6)t(6)A plays a general role in fine-tuning of decoding in organisms from bacteria to mammals.
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Affiliation(s)
- Satoshi Kimura
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Kenjyo Miyauchi
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Yoshiho Ikeuchi
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Patrick C Thiaville
- Genetics and Genomics Graduate Program University of Florida Genetics Institute Department of Microbiology, University of Florida, Gainesville, Florida 32611-0700, USA Institut de Génétique et Microbiologie, Université of Paris-Sud, Orsay, France
| | - Valérie de Crécy-Lagard
- University of Florida Genetics Institute Department of Microbiology, University of Florida, Gainesville, Florida 32611-0700, USA
| | - Tsutomu Suzuki
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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21
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Sinefungin, a natural nucleoside analogue of S-adenosylmethionine, inhibits Streptococcus pneumoniae biofilm growth. BIOMED RESEARCH INTERNATIONAL 2014; 2014:156987. [PMID: 25050323 PMCID: PMC4094849 DOI: 10.1155/2014/156987] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 06/05/2014] [Accepted: 06/08/2014] [Indexed: 01/21/2023]
Abstract
Pneumococcal colonization and disease is often associated with biofilm formation, in which the bacteria exhibit elevated resistance both to antibiotics and to host defense systems, often resulting in infections that are persistent and difficult to treat. We evaluated the effect of sinefungin, a nucleoside analogue of S-adenosylmethionine, on pneumococcal in vitro biofilm formation and in vivo colonization. Sinefungin is bacteriostatic to pneumococci and significantly decreased biofilm growth and inhibited proliferation and structure of actively growing biofilms but did not alter growth or the matrix structure of established biofilms. Sinefungin significantly reduced pneumococcal colonization in rat middle ear. The quorum sensing molecule (autoinducer-2) production was significantly reduced by 92% in sinefungin treated samples. The luxS, pfs, and speE genes were downregulated in biofilms grown in the presence of sinefungin. This study shows that sinefungin inhibits pneumococcal biofilm growth in vitro and colonization in vivo, decreases AI-2 production, and downregulates luxS, pfs, and speE gene expressions. Therefore, the S-adenosylmethionine (SAM) inhibitors could be used as lead compounds for the development of novel antibiofilm agents against pneumococci.
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22
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Loenen WAM, Dryden DTF, Raleigh EA, Wilson GG. Type I restriction enzymes and their relatives. Nucleic Acids Res 2014; 42:20-44. [PMID: 24068554 PMCID: PMC3874165 DOI: 10.1093/nar/gkt847] [Citation(s) in RCA: 171] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 08/26/2013] [Accepted: 08/29/2013] [Indexed: 12/24/2022] Open
Abstract
Type I restriction enzymes (REases) are large pentameric proteins with separate restriction (R), methylation (M) and DNA sequence-recognition (S) subunits. They were the first REases to be discovered and purified, but unlike the enormously useful Type II REases, they have yet to find a place in the enzymatic toolbox of molecular biologists. Type I enzymes have been difficult to characterize, but this is changing as genome analysis reveals their genes, and methylome analysis reveals their recognition sequences. Several Type I REases have been studied in detail and what has been learned about them invites greater attention. In this article, we discuss aspects of the biochemistry, biology and regulation of Type I REases, and of the mechanisms that bacteriophages and plasmids have evolved to evade them. Type I REases have a remarkable ability to change sequence specificity by domain shuffling and rearrangements. We summarize the classic experiments and observations that led to this discovery, and we discuss how this ability depends on the modular organizations of the enzymes and of their S subunits. Finally, we describe examples of Type II restriction-modification systems that have features in common with Type I enzymes, with emphasis on the varied Type IIG enzymes.
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Affiliation(s)
- Wil A. M. Loenen
- Leiden University Medical Center, P.O. Box 9600, 2300 RC, Leiden, The Netherlands, EastChem School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh EH9, 3JJ, Scotland, UK and New England Biolabs Inc., 240 County Road Ipswich, MA 01938-2723, USA
| | - David T. F. Dryden
- Leiden University Medical Center, P.O. Box 9600, 2300 RC, Leiden, The Netherlands, EastChem School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh EH9, 3JJ, Scotland, UK and New England Biolabs Inc., 240 County Road Ipswich, MA 01938-2723, USA
| | - Elisabeth A. Raleigh
- Leiden University Medical Center, P.O. Box 9600, 2300 RC, Leiden, The Netherlands, EastChem School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh EH9, 3JJ, Scotland, UK and New England Biolabs Inc., 240 County Road Ipswich, MA 01938-2723, USA
| | - Geoffrey G. Wilson
- Leiden University Medical Center, P.O. Box 9600, 2300 RC, Leiden, The Netherlands, EastChem School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh EH9, 3JJ, Scotland, UK and New England Biolabs Inc., 240 County Road Ipswich, MA 01938-2723, USA
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23
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Driesener RC, Duffus BR, Shepard EM, Bruzas IR, Duschene KS, Coleman NJR, Marrison APG, Salvadori E, Kay CWM, Peters JW, Broderick JB, Roach PL. Biochemical and kinetic characterization of radical S-adenosyl-L-methionine enzyme HydG. Biochemistry 2013; 52:8696-707. [PMID: 24206022 DOI: 10.1021/bi401143s] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The radical S-adenosyl-L-methionine (AdoMet) enzyme HydG is one of three maturase enzymes involved in [FeFe]-hydrogenase H-cluster assembly. It catalyzes L-tyrosine cleavage to yield the H-cluster cyanide and carbon monoxide ligands as well as p-cresol. Clostridium acetobutylicum HydG contains the conserved CX3CX2C motif coordinating the AdoMet binding [4Fe-4S] cluster and a C-terminal CX2CX22C motif proposed to coordinate a second [4Fe-4S] cluster. To improve our understanding of the roles of each of these iron-sulfur clusters in catalysis, we have generated HydG variants lacking either the N- or C-terminal cluster and examined these using spectroscopic and kinetic methods. We have used iron analyses, UV-visible spectroscopy, and electron paramagnetic resonance (EPR) spectroscopy of an N-terminal C96/100/103A triple HydG mutant that cannot coordinate the radical AdoMet cluster to unambiguously show that the C-terminal cysteine motif coordinates an auxiliary [4Fe-4S] cluster. Spectroscopic comparison with a C-terminally truncated HydG (ΔCTD) harboring only the N-terminal cluster demonstrates that both clusters have similar UV-visible and EPR spectral properties, but that AdoMet binding and cleavage occur only at the N-terminal radical AdoMet cluster. To elucidate which steps in the catalytic cycle of HydG require the auxiliary [4Fe-4S] cluster, we compared the Michaelis-Menten constants for AdoMet and L-tyrosine for reconstituted wild-type, C386S, and ΔCTD HydG and demonstrate that these C-terminal modifications do not affect the affinity for AdoMet but that the affinity for L-tyrosine is drastically reduced compared to that of wild-type HydG. Further detailed kinetic characterization of these HydG mutants demonstrates that the C-terminal cluster and residues are not essential for L-tyrosine cleavage to p-cresol but are necessary for conversion of a tyrosine-derived intermediate to cyanide and CO.
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Affiliation(s)
- Rebecca C Driesener
- Chemistry, Faculty of Natural and Engineering Sciences, University of Southampton , Highfield SO17 1BJ, U.K
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24
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Gros C, Chauvigné L, Poulet A, Menon Y, Ausseil F, Dufau I, Arimondo PB. Development of a universal radioactive DNA methyltransferase inhibition test for high-throughput screening and mechanistic studies. Nucleic Acids Res 2013; 41:e185. [PMID: 23980028 PMCID: PMC3799459 DOI: 10.1093/nar/gkt753] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Revised: 07/15/2013] [Accepted: 07/30/2013] [Indexed: 12/24/2022] Open
Abstract
DNA methylation is an important epigenetic mark in eukaryotes, and aberrant pattern of this modification is involved in numerous diseases such as cancers. Interestingly, DNA methylation is reversible and thus is considered a promising therapeutic target. Therefore, there is a need for identifying new small inhibitors of C5 DNA methyltransferases (DNMTs). Despite the development of numerous in vitro DNMT assays, there is a lack of reliable tests suitable for high-throughput screening, which can also give insights into inhibitor mechanisms of action. We developed a new test based on scintillation proximity assay meeting these requirements. After optimizing our assay on human DNMT1 and calibrating it with two known inhibitors, we carried out S-Adenosyl-l-Methionine and DNA competition studies on three inhibitors and were able to determine each mechanism of action. Finally, we showed that our test was applicable to 3 other methyltransferases sources: human DNMT3A, bacterial M.SssI and cellular extracts as well.
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Affiliation(s)
| | | | | | | | | | - Isabelle Dufau
- CNRS-Pierre Fabre USR n° 3388 ETaC, CRDPF, 3 Avenue H. Curien, 31035 Toulouse Cedex 01, France
| | - Paola B. Arimondo
- CNRS-Pierre Fabre USR n° 3388 ETaC, CRDPF, 3 Avenue H. Curien, 31035 Toulouse Cedex 01, France
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25
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Kilgore JA, Du X, Melito L, Wei S, Wang C, Chin HG, Posner B, Pradhan S, Ready JM, Williams NS. Identification of DNMT1 selective antagonists using a novel scintillation proximity assay. J Biol Chem 2013; 288:19673-84. [PMID: 23671287 PMCID: PMC3707673 DOI: 10.1074/jbc.m112.443895] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 05/02/2013] [Indexed: 11/06/2022] Open
Abstract
A novel scintillation proximity high throughput assay (SPA) to identify inhibitors of DNA methyltransferases was developed and used to screen over 180,000 compounds. The majority of the validated hits shared a quinone core and several were found to generate the reactive oxygen species, H2O2. Inhibition of the production of H2O2 by the addition of catalase blocked the ability of this group of compounds to inhibit DNA methyltransferase (DNMT) activity. However, a related compound, SW155246, was identified that existed in an already reduced form of the quinone. This compound did not generate H2O2, and catalase did not block its ability to inhibit DNA methyltransferase. SW155246 showed a 30-fold preference for inhibition of human DNMT1 versus human or murine DNMT3A or -3B, inhibited global methylation in HeLa cells, and reactivated expression of the tumor suppressor gene RASSF1A in A549 cells. To our knowledge, this work represents the first description of selective chemical inhibitors of the DNMT1 enzyme.
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Affiliation(s)
- Jessica A. Kilgore
- From the Department of Biochemistry, University of Texas
Southwestern Medical Center at Dallas, Dallas, Texas 75390 and
| | - Xinlin Du
- From the Department of Biochemistry, University of Texas
Southwestern Medical Center at Dallas, Dallas, Texas 75390 and
| | - Lisa Melito
- From the Department of Biochemistry, University of Texas
Southwestern Medical Center at Dallas, Dallas, Texas 75390 and
| | - Shuguang Wei
- From the Department of Biochemistry, University of Texas
Southwestern Medical Center at Dallas, Dallas, Texas 75390 and
| | - Changguang Wang
- From the Department of Biochemistry, University of Texas
Southwestern Medical Center at Dallas, Dallas, Texas 75390 and
| | | | - Bruce Posner
- From the Department of Biochemistry, University of Texas
Southwestern Medical Center at Dallas, Dallas, Texas 75390 and
| | | | - Joseph M. Ready
- From the Department of Biochemistry, University of Texas
Southwestern Medical Center at Dallas, Dallas, Texas 75390 and
| | - Noelle S. Williams
- From the Department of Biochemistry, University of Texas
Southwestern Medical Center at Dallas, Dallas, Texas 75390 and
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26
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Challand MR, Salvadori E, Driesener RC, Kay CWM, Roach PL, Spencer J. Cysteine methylation controls radical generation in the Cfr radical AdoMet rRNA methyltransferase. PLoS One 2013; 8:e67979. [PMID: 23861844 PMCID: PMC3702613 DOI: 10.1371/journal.pone.0067979] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 05/23/2013] [Indexed: 11/18/2022] Open
Abstract
The 'radical S-adenosyl-L-methionine (AdoMet)' enzyme Cfr methylates adenosine 2503 of the 23S rRNA in the peptidyltransferase centre (P-site) of the bacterial ribosome. This modification protects host bacteria, notably methicillin-resistant Staphylococcus aureus (MRSA), from numerous antibiotics, including agents (e.g. linezolid, retapamulin) that were developed to treat such organisms. Cfr contains a single [4Fe-4S] cluster that binds two separate molecules of AdoMet during the reaction cycle. These are used sequentially to first methylate a cysteine residue, Cys338; and subsequently generate an oxidative radical intermediate that facilitates methyl transfer to the unreactive C8 (and/or C2) carbon centres of adenosine 2503. How the Cfr active site, with its single [4Fe-4S] cluster, catalyses these two distinct activities that each utilise AdoMet as a substrate remains to be established. Here, we use absorbance and electron paramagnetic resonance (EPR) spectroscopy to investigate the interactions of AdoMet with the [4Fe-4S] clusters of wild-type Cfr and a Cys338 Ala mutant, which is unable to accept a methyl group. Cfr binds AdoMet with high (∼ 10 µM) affinity notwithstanding the absence of the RNA cosubstrate. In wild-type Cfr, where Cys338 is methylated, AdoMet binding leads to rapid oxidation of the [4Fe-4S] cluster and production of 5'-deoxyadenosine (DOA). In contrast, while Cys338 Ala Cfr binds AdoMet with equivalent affinity, oxidation of the [4Fe-4S] cluster is not observed. Our results indicate that the presence of a methyl group on Cfr Cys338 is a key determinant of the activity of the enzyme towards AdoMet, thus enabling a single active site to support two distinct modes of AdoMet cleavage.
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Affiliation(s)
- Martin R. Challand
- School of Cellular and Molecular Medicine, University of Bristol Medical Sciences Building, Bristol, United Kingdom
| | - Enrico Salvadori
- Institute of Structural and Molecular Biology, University College London, London, United Kingdom
- London Centre for Nanotechnology, University College London, London, United Kingdom
| | | | - Christopher W. M. Kay
- Institute of Structural and Molecular Biology, University College London, London, United Kingdom
- London Centre for Nanotechnology, University College London, London, United Kingdom
- * E-mail: (CWMK); (PLR); (JS)
| | - Peter L. Roach
- Chemistry, University of Southampton, Highfield, Southampton, United Kingdom
- Institute for Life Sciences, University of Southampton, Highfield, Southampton, United Kingdom
- * E-mail: (CWMK); (PLR); (JS)
| | - James Spencer
- School of Cellular and Molecular Medicine, University of Bristol Medical Sciences Building, Bristol, United Kingdom
- * E-mail: (CWMK); (PLR); (JS)
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27
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Guja KE, Venkataraman K, Yakubovskaya E, Shi H, Mejia E, Hambardjieva E, Karzai AW, Garcia-Diaz M. Structural basis for S-adenosylmethionine binding and methyltransferase activity by mitochondrial transcription factor B1. Nucleic Acids Res 2013; 41:7947-59. [PMID: 23804760 PMCID: PMC3763538 DOI: 10.1093/nar/gkt547] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Eukaryotic transcription factor B (TFB) proteins are homologous to KsgA/Dim1 ribosomal RNA (rRNA) methyltransferases. The mammalian TFB1, mitochondrial (TFB1M) factor is an essential protein necessary for mitochondrial gene expression. TFB1M mediates an rRNA modification in the small ribosomal subunit and thus plays a role analogous to KsgA/Dim1 proteins. This modification has been linked to mitochondrial dysfunctions leading to maternally inherited deafness, aminoglycoside sensitivity and diabetes. Here, we present the first structural characterization of the mammalian TFB1 factor. We have solved two X-ray crystallographic structures of TFB1M with (2.1 Å) and without (2.0 Å) its cofactor S-adenosyl-L-methionine. These structures reveal that TFB1M shares a conserved methyltransferase core with other KsgA/Dim1 methyltransferases and shed light on the structural basis of S-adenosyl-L-methionine binding and methyltransferase activity. Together with mutagenesis studies, these data suggest a model for substrate binding and provide insight into the mechanism of methyl transfer, clarifying the role of this factor in an essential process for mitochondrial function.
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Affiliation(s)
- Kip E Guja
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY 11794, USA, Medical Scientist Training Program, Stony Brook University Medical Center, Stony Brook, NY 11794, USA and Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA
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28
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Jurkowski TP, Shanmugam R, Helm M, Jeltsch A. Mapping the tRNA Binding Site on the Surface of Human DNMT2 Methyltransferase. Biochemistry 2012; 51:4438-44. [DOI: 10.1021/bi3002659] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Tomasz P. Jurkowski
- Biochemistry Laboratory, School
of Engineering and Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany, and Institute of Biochemistry,
Faculty of Chemistry, Stuttgart University, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Raghuvaran Shanmugam
- Biochemistry Laboratory, School
of Engineering and Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany, and Institute of Biochemistry,
Faculty of Chemistry, Stuttgart University, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Mark Helm
- Institute of Pharmacy and Biochemistry, Johannes Gutenberg-Universität Mainz, Staudinger
Weg 5, 55128 Mainz, Germany
| | - Albert Jeltsch
- Biochemistry Laboratory, School
of Engineering and Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany, and Institute of Biochemistry,
Faculty of Chemistry, Stuttgart University, Pfaffenwaldring 55, 70569 Stuttgart, Germany
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29
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Fislage M, Roovers M, Tuszynska I, Bujnicki JM, Droogmans L, Versées W. Crystal structures of the tRNA:m2G6 methyltransferase Trm14/TrmN from two domains of life. Nucleic Acids Res 2012; 40:5149-61. [PMID: 22362751 PMCID: PMC3367198 DOI: 10.1093/nar/gks163] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Methyltransferases (MTases) form a major class of tRNA-modifying enzymes needed for the proper functioning of tRNA. Recently, RNA MTases from the TrmN/Trm14 family that are present in Archaea, Bacteria and Eukaryota have been shown to specifically modify tRNAPhe at guanosine 6 in the tRNA acceptor stem. Here, we report the first X-ray crystal structures of the tRNA m2G6 (N2-methylguanosine) MTase TTCTrmN from Thermus thermophilus and its ortholog PfTrm14 from Pyrococcus furiosus. Structures of PfTrm14 were solved in complex with the methyl donor S-adenosyl-l-methionine (SAM or AdoMet), as well as the reaction product S-adenosyl-homocysteine (SAH or AdoHcy) and the inhibitor sinefungin. TTCTrmN and PfTrm14 consist of an N-terminal THUMP domain fused to a catalytic Rossmann-fold MTase (RFM) domain. These results represent the first crystallographic structure analysis of proteins containing both THUMP and RFM domain, and hence provide further insight in the contribution of the THUMP domain in tRNA recognition and catalysis. Electrostatics and conservation calculations suggest a main tRNA binding surface in a groove between the THUMP domain and the MTase domain. This is further supported by a docking model of TrmN in complex with tRNAPhe of T. thermophilus and via site-directed mutagenesis.
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Affiliation(s)
- Marcus Fislage
- VIB Department of Structural Biology, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussel, Belgium
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30
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O'Farrell HC, Musayev FN, Scarsdale JN, Rife JP. Control of substrate specificity by a single active site residue of the KsgA methyltransferase. Biochemistry 2011; 51:466-74. [PMID: 22142337 DOI: 10.1021/bi201539j] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The KsgA methyltransferase is universally conserved and plays a key role in regulating ribosome biogenesis. KsgA has a complex reaction mechanism, transferring a total of four methyl groups onto two separate adenosine residues, A1518 and A1519, in the small subunit rRNA. This means that the active site pocket must accept both adenosine and N(6)-methyladenosine as substrates to catalyze formation of the final product N(6),N(6)-dimethyladenosine. KsgA is related to DNA adenosine methyltransferases, which transfer only a single methyl group to their target adenosine residue. We demonstrate that part of the discrimination between mono- and dimethyltransferase activity lies in a single residue in the active site, L114; this residue is part of a conserved motif, known as motif IV, which is common to a large group of S-adenosyl-L-methionine-dependent methyltransferases. Mutation of the leucine to a proline mimics the sequence found in DNA methyltransferases. The L114P mutant of KsgA shows diminished overall activity, and its ability to methylate the N(6)-methyladenosine intermediate to produce N(6),N(6)-dimethyladenosine is impaired; this is in contrast to a second active site mutation, N113A, which diminishes activity to a level comparable to L114P without affecting the methylation of N(6)-methyladenosine. We discuss the implications of this work for understanding the mechanism of KsgA's multiple catalytic steps.
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Affiliation(s)
- Heather C O'Farrell
- Department of Physiology and Molecular Biophysics, Virginia Commonwealth University, Richmond, Virginia 23219, United States
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31
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Ceccaldi A, Rajavelu A, Champion C, Rampon C, Jurkowska R, Jankevicius G, Sénamaud-Beaufort C, Ponger L, Gagey N, Dali Ali H, Tost J, Vriz S, Ros S, Dauzonne D, Jeltsch A, Guianvarc'h D, Arimondo PB. C5-DNA Methyltransferase Inhibitors: From Screening to Effects on Zebrafish Embryo Development. Chembiochem 2011; 12:1337-45. [DOI: 10.1002/cbic.201100130] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Indexed: 12/28/2022]
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32
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Choudhury HG, Beis K. Crystallization and initial X-ray diffraction analysis of the tellurite-resistance S-adenosyl-L-methionine transferase protein TehB from Escherichia coli. Acta Crystallogr Sect F Struct Biol Cryst Commun 2010; 66:1496-9. [PMID: 21045305 DOI: 10.1107/s1744309110036043] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Accepted: 09/07/2010] [Indexed: 11/10/2022]
Abstract
TehB is an S-adenosyl-L-methionine (SAM) dependent methyltransferase that detoxifies tellurite in bacteria. The Escherichia coli TehB protein was purified and crystallized in the presence of both SAM and sinefungin. The TehB-SAM and TehB-sinefungin crystals both diffracted X-rays to 1.9 Å resolution. The TehB-SAM crystals belonged to space group C2, with unit-cell parameters a = 60.0, b = 56.1, c = 130.6 Å, β = 97.9°. The TehB-sinefungin crystals belonged to space group P2(1), with unit-cell parameters a = 59.1, b = 55.5, c = 129.7 Å, β = 95.9°.
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Affiliation(s)
- Hassanul Ghani Choudhury
- Membrane Protein Laboratory, Diamond Light Source, Harwell Science and Innovation Campus, Chilton, Oxfordshire OX11 0DE, England
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33
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Guelorget A, Roovers M, Guérineau V, Barbey C, Li X, Golinelli-Pimpaneau B. Insights into the hyperthermostability and unusual region-specificity of archaeal Pyrococcus abyssi tRNA m1A57/58 methyltransferase. Nucleic Acids Res 2010; 38:6206-18. [PMID: 20483913 PMCID: PMC2952851 DOI: 10.1093/nar/gkq381] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The S-adenosyl-L-methionine dependent methylation of adenine 58 in the T-loop of tRNAs is essential for cell growth in yeast or for adaptation to high temperatures in thermophilic organisms. In contrast to bacterial and eukaryotic tRNA m(1)A58 methyltransferases that are site-specific, the homologous archaeal enzyme from Pyrococcus abyssi catalyzes the formation of m(1)A also at the adjacent position 57, m(1)A57 being a precursor of 1-methylinosine. We report here the crystal structure of P. abyssi tRNA m(1)A57/58 methyltransferase ((Pab)TrmI), in complex with S-adenosyl-L-methionine or S-adenosyl-L-homocysteine in three different space groups. The fold of the monomer and the tetrameric architecture are similar to those of the bacterial enzymes. However, the inter-monomer contacts exhibit unique features. In particular, four disulfide bonds contribute to the hyperthermostability of the archaeal enzyme since their mutation lowers the melting temperature by 16.5°C. His78 in conserved motif X, which is present only in TrmIs from the Thermococcocales order, lies near the active site and displays two alternative conformations. Mutagenesis indicates His78 is important for catalytic efficiency of (Pab)TrmI. When A59 is absent in tRNA(Asp), only A57 is modified. Identification of the methylated positions in tRNAAsp by mass spectrometry confirms that (Pab)TrmI methylates the first adenine of an AA sequence.
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Affiliation(s)
- Amandine Guelorget
- Laboratoire d'Enzymologie et Biochimie Structurales, CNRS, 1 avenue de la Terrasse, 91198 Gif-sur-Yvette, France
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34
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O'Farrell HC, Musayev FN, Scarsdale JN, Rife JP. Binding of adenosine-based ligands to the MjDim1 rRNA methyltransferase: implications for reaction mechanism and drug design. Biochemistry 2010; 49:2697-704. [PMID: 20163168 DOI: 10.1021/bi901875x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The KsgA/Dim1 family of proteins is intimately involved in ribosome biogenesis in all organisms. These enzymes share the common function of dimethylating two adenosine residues near the 3'-OH end of the small subunit rRNA; orthologs in the three kingdoms, along with eukaryotic organelles, have evolved additional functions in rRNA processing, ribosome assembly, and, surprisingly, transcription in mitochondria. The methyltransferase reaction is intriguingly elaborate. The enzymes can bind to naked small subunit rRNA but cannot methylate their target bases until a subset of ribosomal proteins have bound and the nascent subunit has reached a certain level of maturity. Once this threshold is reached, the enzyme must stabilize two adenosines into the active site at separate times and two methyl groups must be transferred to each adenosine, with concomitant exchanges of the product S-adenosyl-l-homocysteine and the methyl donor substrate S-adenosyl-l-methionine. A detailed molecular understanding of this mechanism is currently lacking. Structural analysis of the interactions between the enzyme and substrate will aid in this understanding. Here we present the structure of KsgA from Methanocaldococcus jannaschii in complex with several ligands, including the first structure of S-adenosyl-l-methionine bound to a KsgA/Dim1 enzyme in a catalytically productive way. We also discuss the inability thus far to determine a structure of a target adenosine bound in its active site.
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Affiliation(s)
- Heather C O'Farrell
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, Virginia 23298-0133, USA
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35
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Dalhoff C, Hüben M, Lenz T, Poot P, Nordhoff E, Köster H, Weinhold E. Synthesis of S-Adenosyl-L-homocysteine Capture Compounds for Selective Photoinduced Isolation of Methyltransferases. Chembiochem 2010; 11:256-65. [DOI: 10.1002/cbic.200900349] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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36
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Xu F, Mao C, Ding Y, Rui C, Wu L, Shi A, Zhang H, Zhang L, Xu Z. Molecular and enzymatic profiles of mammalian DNA methyltransferases: structures and targets for drugs. Curr Med Chem 2010; 17:4052-71. [PMID: 20939822 PMCID: PMC3003592 DOI: 10.2174/092986710793205372] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2010] [Accepted: 09/20/2010] [Indexed: 12/29/2022]
Abstract
DNA methylation is an epigenetic event involved in a variety array of processes that may be the foundation of genetic phenomena and diseases. DNA methyltransferase is a key enzyme for cytosine methylation in DNA, and can be divided into two functional families (Dnmt1 and Dnmt3) in mammals. All mammalian DNA methyltransferases are encoded by their own single gene, and consisted of catalytic and regulatory regions (except Dnmt2). Via interactions between functional domains in the regulatory or catalytic regions and other adaptors or cofactors, DNA methyltransferases can be localized at selective areas (specific DNA/nucleotide sequence) and linked to specific chromosome status (euchromatin/heterochromatin, various histone modification status). With assistance from UHRF1 and Dnmt3L or other factors in Dnmt1 and Dnmt3a/Dnmt3b, mammalian DNA methyltransferases can be recruited, and then specifically bind to hemimethylated and unmethylated double-stranded DNA sequence to maintain and de novo setup patterns for DNA methylation. Complicated enzymatic steps catalyzed by DNA methyltransferases include methyl group transferred from cofactor Ado-Met to C5 position of the flipped-out cytosine in targeted DNA duplex. In the light of the fact that different DNA methyltransferases are divergent in both structures and functions, and use unique reprogrammed or distorted routines in development of diseases, design of new drugs targeting specific mammalian DNA methyltransferases or their adaptors in the control of key steps in either maintenance or de novo DNA methylation processes will contribute to individually treating diseases related to DNA methyltransferases.
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Affiliation(s)
- F. Xu
- First Hospital & Perinatal Biology Center of Soochow University, Suzhou 215123, China
| | - C. Mao
- First Hospital & Perinatal Biology Center of Soochow University, Suzhou 215123, China
| | - Y. Ding
- First Hospital & Perinatal Biology Center of Soochow University, Suzhou 215123, China
| | - C. Rui
- First Hospital & Perinatal Biology Center of Soochow University, Suzhou 215123, China
| | - L. Wu
- First Hospital & Perinatal Biology Center of Soochow University, Suzhou 215123, China
| | - A. Shi
- First Hospital & Perinatal Biology Center of Soochow University, Suzhou 215123, China
| | - H. Zhang
- First Hospital & Perinatal Biology Center of Soochow University, Suzhou 215123, China
| | - L. Zhang
- Center for Perinatal Biology, Loma Linda University School of Medicine, CA 92350, USA
| | - Z. Xu
- First Hospital & Perinatal Biology Center of Soochow University, Suzhou 215123, China
- Center for Perinatal Biology, Loma Linda University School of Medicine, CA 92350, USA
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37
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Tu C, Tropea JE, Austin BP, Court DL, Waugh DS, Ji X. Structural basis for binding of RNA and cofactor by a KsgA methyltransferase. Structure 2009; 17:374-85. [PMID: 19278652 DOI: 10.1016/j.str.2009.01.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2008] [Revised: 12/23/2008] [Accepted: 01/06/2009] [Indexed: 11/19/2022]
Abstract
Among methyltransferases, KsgA and the reaction it catalyzes are conserved throughout evolution. However, the specifics of substrate recognition by the enzyme remain unknown. Here we report structures of Aquifex aeolicus KsgA, in its ligand-free form, in complex with RNA, and in complex with both RNA and S-adenosylhomocysteine (SAH, reaction product of cofactor S-adenosylmethionine), revealing critical structural information on KsgA-RNA and KsgA-SAH interactions. Moreover, the structures show how conformational changes that occur upon RNA binding create the cofactor-binding site. There are nine conserved functional motifs (motifs I-VIII and X) in KsgA. Prior to RNA binding, motifs I and VIII are flexible, each exhibiting two distinct conformations. Upon RNA binding, the two motifs become stabilized in one of these conformations, which is compatible with the binding of SAH. Motif X, which is also stabilized upon RNA binding, is directly involved in the binding of SAH.
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Affiliation(s)
- Chao Tu
- Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD 21702, USA
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38
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Suzuki Y, Noma A, Suzuki T, Ishitani R, Nureki O. Structural basis of tRNA modification with CO2 fixation and methylation by wybutosine synthesizing enzyme TYW4. Nucleic Acids Res 2009; 37:2910-25. [PMID: 19287006 PMCID: PMC2685095 DOI: 10.1093/nar/gkp158] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Wybutosine (yW), one of the most complicated modified nucleosides, is found in the anticodon loop of eukaryotic phenylalanine tRNA. This hypermodified nucleoside ensures correct codon recognition by stabilizing codon-anticodon pairings during the decoding process in the ribosome. TYW4 is an S-adenosylmethionine (SAM)-dependent enzyme that catalyzes the final step of yW biosynthesis, methylation and methoxycarbonylation. However, the structural basis for the catalytic mechanism by TYW4, and especially that for the methoxycarbonylation, have remained elusive. Here we report the apo and cofactor-bound crystal structures of yeast TYW4. The structures revealed that the C-terminal domain folds into a beta-propeller structure, forming part of the binding pocket for the target nucleoside. A comparison of the apo, SAM-bound, and S-adenosylhomocysteine-bound structures of TYW4 revealed a drastic structural change upon cofactor binding, which may sequester solvent from the catalytic site during the reaction and facilitate product release after the reaction. In conjunction with the functional analysis, our results suggest that TYW4 catalyzes both methylation and methoxycarbonylation at a single catalytic site, and in the latter reaction, the methoxycarbonyl group is formed through the fixation of carbon dioxide.
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Affiliation(s)
- Yoko Suzuki
- Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama-shi, Kanagawa, Japan
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39
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Nakonieczna J, Zmijewski JW, Banecki B, Podhajska AJ. Binding of MmeI restriction-modification enzyme to its specific recognition sequence is stimulated by S-adenosyl-L-methionine. Mol Biotechnol 2008; 37:127-35. [PMID: 17914173 DOI: 10.1007/s12033-007-0034-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/1999] [Revised: 11/30/1999] [Accepted: 11/30/1999] [Indexed: 11/29/2022]
Abstract
Restriction endonucleases serve as a very good model for studying specific protein-DNA interaction. MmeI is a very interesting restriction endonuclease, but although it is useful in Serial Analysis of Gene Expression, still very little is known about the mechanism of its interaction with DNA. MmeI is a unique enzyme as besides cleaving DNA it also methylates specific sequence. For endonucleolytic activity MmeI requires Mg(II) and S-adenosyl-l-methionine (AdoMet). AdoMet is a methyl donor in the methylation reaction, but its requirement for DNA cleavage remains unclear. In the present article we investigated MmeI interaction with DNA with the use of numerous methods. Our electrophoretic mobility shift assay revealed formation of two types of specific protein-DNA complexes. We speculate that faster migrating complex consists of one protein molecule and one DNA fragment whereas, slower migrating complex, which appears in the presence of AdoMet, may be a dimer or multimer form of MmeI interacting with specific DNA. Additionally, using spectrophotometric measurements we showed that in the presence of AdoMet, MmeI protein undergoes conformational changes. We think that such change in the enzyme structure, upon addition of AdoMet, may enhance its specific binding to DNA. In the absence of AdoMet MmeI binds DNA to the much lower extent.
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Affiliation(s)
- Joanna Nakonieczna
- Intercollegiate Faculty of Biotechnology, Department of Biotechnology, University of Gdansk and Medical University of Gdansk, Kladki 24, Gdansk, 80-822, Poland.
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40
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Zheng S, Shuman S, Schwer B. Sinefungin resistance of Saccharomyces cerevisiae arising from Sam3 mutations that inactivate the AdoMet transporter or from increased expression of AdoMet synthase plus mRNA cap guanine-N7 methyltransferase. Nucleic Acids Res 2007; 35:6895-903. [PMID: 17932050 PMCID: PMC2175321 DOI: 10.1093/nar/gkm817] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The S-adenosylmethionine (AdoMet) analog sinefungin is a natural product antibiotic that inhibits nucleic acid methyltransferases and arrests the growth of unicellular eukarya and eukaryal viruses. The basis for the particular sensitivity of fungi and protozoa to sinefungin is not known. Here we report the isolation and characterization of spontaneous sinefungin-resistant mutants of the budding yeast Saccharomyces cerevisiae. In all cases, sinefungin resistance was attributable to a loss-of-function mutation in Sam3, the yeast high-affinity AdoMet transporter. Overexpression of wild-type Sam3 increased the sensitivity of yeast to growth inhibition by sinefungin. Thus, Sam3 is a tunable determinant of sinefungin potency. The shared ability of protozoan parasites to import AdoMet might determine sinefungin's anti-infective spectrum. Insights to the intracellular action of sinefungin stem from the finding that increased gene dosage of yeast AdoMet synthase plus cap guanine-N7 methyltransferase afforded greater resistance to sinefungin than either enzyme alone. These results are consistent with the proposal that mRNA cap methylation is a principal target of sinefungin's bioactivity.
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Affiliation(s)
- Sushuang Zheng
- Molecular Biology Program, Sloan-Kettering Institute and Microbiology, Weill Cornell Medical College, New York, NY 10065, USA
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41
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Pljevaljcić G, Schmidt F, Scheidig AJ, Lurz R, Weinhold E. Quantitative Labeling of Long Plasmid DNA with Nanometer Precision. Chembiochem 2007; 8:1516-9. [PMID: 17654629 DOI: 10.1002/cbic.200700294] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Goran Pljevaljcić
- Present address: Department of Molecular Biology, MB19, The Scripps Research Institute, 10550 N. Torrey Pines Rd. La Jolla, CA 92037, USA
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42
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Evdokimov AA, Sclavi B, Zinoviev VV, Malygin EG, Hattman S, Buckle M. Study of Bacteriophage T4-encoded Dam DNA (Adenine-N6)-methyltransferase Binding with Substrates by Rapid Laser UV Cross-linking. J Biol Chem 2007; 282:26067-76. [PMID: 17630395 DOI: 10.1074/jbc.m700866200] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
DNA methyltransferases of the Dam family (including bacteriophage T4-encoded Dam DNA (adenine-N(6))-methyltransferase (T4Dam)) catalyze methyl group transfer from S-adenosyl-L-methionine (AdoMet), producing S-adenosyl-L-homocysteine (AdoHcy) and methylated adenine residues in palindromic GATC sequences. In this study, we describe the application of direct (i.e. no exogenous cross-linking reagents) laser UV cross-linking as a universal non-perturbing approach for studying the characteristics of T4Dam binding with substrates in the equilibrium and transient modes of interaction. UV irradiation of the enzyme.substrate complexes using an Nd(3+):yttrium aluminum garnet laser at 266 nm resulted in up to 3 and >15% yields of direct T4Dam cross-linking to DNA and AdoMet, respectively. Consequently, we were able to measure equilibrium constants and dissociation rates for enzyme.substrate complexes. In particular, we demonstrate that both reaction substrates, specific DNA and AdoMet (or product AdoHcy), stabilized the ternary complex. The improved substrate affinity for the enzyme in the ternary complex significantly reduced dissociation rates (up to 2 orders of magnitude). Several of the parameters obtained (such as dissociation rate constants for the binary T4Dam.AdoMet complex and for enzyme complexes with a nonfluorescent hemimethylated DNA duplex) were previously inaccessible by other means. However, where possible, the results of laser UV cross-linking were compared with those of fluorescence analysis. Our study suggests that rapid laser UV cross-linking efficiently complements standard DNA methyltransferase-related tools and is a method of choice to probe enzyme-substrate interactions in cases in which data cannot be acquired by other means.
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Affiliation(s)
- Alexey A Evdokimov
- Federal State Research Institute State Research Center of Virology and Biotechnology Vector, Novosibirsk 630559, Russia
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43
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Cappannelli M, Gaggelli E, Jezowska-Bojczuk M, Molteni E, Mucha A, Porciatti E, Valensin D, Valensin G. 1H and 13C NMR study of the complex formed by copper(II) with the nucleoside antibiotic sinefungin. J Inorg Biochem 2007; 101:1005-12. [PMID: 17531321 DOI: 10.1016/j.jinorgbio.2007.03.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2006] [Revised: 03/08/2007] [Accepted: 03/11/2007] [Indexed: 11/17/2022]
Abstract
Sinefungin (SFG) is an antifungal and antiparasitic nucleoside antibiotic composed by ornithine and adenosine moieties both having the potential to bind copper(II). NMR studies performed at physiological pH have shown that the alpha-amino and the carboxylate groups in the ornithine unit are the preferred donor sites for Cu(II) binding. On the contrary, at acidic pH, Cu(II) complexation starts from adenosine nitrogen being the alpha-amino group still protonated and not available for metal binding. The proton paramagnetic relaxation enhancements measured at neutral pH allowed to obtain the 3D structure of the 1:2 Cu(II)-SFG complex. Molecular dynamics calculations were revealing for the existence of secondary Cu(II) interaction with the purine nitrogens of the adenosine moiety.
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Affiliation(s)
- Massimo Cappannelli
- Department of Chemistry, University of Siena, Via Aldo Moro, 53100 Siena, Italy
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44
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Jiang MXW, Jin B, Gage JL, Priour A, Savela G, Miller MJ. Substrate-dependent dihydroxylation of substituted cyclopentenes: toward the syntheses of carbocyclic sinefungin and noraristeromycin. J Org Chem 2007; 71:4164-9. [PMID: 16709056 PMCID: PMC2652561 DOI: 10.1021/jo060224l] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Carbocyclic nucleosides are of considerable interest for the development of new therapeutic agents. A key reaction in the preparation of many such nucleoside analogues is dihydroxylation of appropriately substituted cyclopentenes. Although often considered a routine reaction, in this paper, we report the dramatic influence of substituents on the facial selectivity of dihydroxylations. The substituted cyclopentene substrates are derived from acylnitroso cycloaddition reactions of cyclopentadiene, followed by N-O reduction and efficient enzymatic resolution. The results are directly utilized in a very efficient asymmetric synthesis of an antiviral carbocyclic nucleoside, noraristeromycin 5. Extensions toward the synthesis of carbocyclic sinefungin 7 document the importance of realizing the substituent dependence of the dihydroxylation reaction.
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Affiliation(s)
- May Xiao-Wu Jiang
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670, USA
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45
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Liebert K, Horton JR, Chahar S, Orwick M, Cheng X, Jeltsch A. Two alternative conformations of S-adenosyl-L-homocysteine bound to Escherichia coli DNA adenine methyltransferase and the implication of conformational changes in regulating the catalytic cycle. J Biol Chem 2007; 282:22848-55. [PMID: 17545164 DOI: 10.1074/jbc.m700926200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The crystal structure of the Escherichia coli DNA adenine methyltransferase (EcoDam) in a binary complex with the cofactor product S-adenosyl-L-homocysteine (AdoHcy) unexpectedly showed the bound AdoHcy in two alternative conformations, extended or folded. The extended conformation represents the catalytically competent conformation, identical to that of EcoDam-DNA-AdoHcy ternary complex. The folded conformation prevents catalysis, because the homocysteine moiety occupies the target Ade binding pocket. The largest difference between the binary and ternary structures is in the conformation of the N-terminal hexapeptide ((9)KWAGGK(14)). Cofactor binding leads to a strong change in the fluorescence of Trp(10), whose indole ring approaches the cofactor by 3.3A(.) Stopped-flow kinetics and AdoMet cross-linking studies indicate that the cofactor prefers binding to the enzyme after preincubation with DNA. In the presence of DNA, AdoMet binding is approximately 2-fold stronger than AdoHcy binding. In the binary complex the side chain of Lys(14) is disordered, whereas Lys(14) stabilizes the active site in the ternary complex. Fluorescence stopped-flow experiments indicate that Lys(14) is important for EcoDam binding of the extrahelical target base into the active site pocket. This suggests that the hexapeptide couples specific DNA binding (Lys(9)), AdoMet binding (Trp(10)), and insertion of the flipped target base into the active site pocket (Lys(14)).
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Affiliation(s)
- Kirsten Liebert
- Biochemistry Laboratory, School of Engineering and Science, Jacobs University Bremen, 28759 Bremen, Germany
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46
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Lenz T, Bonnist EYM, Pljevaljcić G, Neely RK, Dryden DTF, Scheidig AJ, Jones AC, Weinhold E. 2-Aminopurine Flipped into the Active Site of the Adenine-Specific DNA Methyltransferase M.TaqI: Crystal Structures and Time-Resolved Fluorescence. J Am Chem Soc 2007; 129:6240-8. [PMID: 17455934 DOI: 10.1021/ja069366n] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report the crystal structure of the DNA adenine-N6 methyltransferase, M.TaqI, complexed with DNA, showing the fluorescent adenine analog, 2-aminopurine, flipped out of the DNA helix and occupying virtually the same position in the active site as the natural target adenine. Time-resolved fluorescence spectroscopy of the crystalline complex faithfully reports this state: base flipping is accompanied by the loss of the very short ( approximately 50 ps) lifetime component associated with fully base-stacked 2-aminopurine in DNA, and 2-aminopurine is subject to considerable quenching by pi-stacking interactions with Tyr108 in the catalytic motif IV (NPPY). This proves 2-aminopurine to be an excellent probe for studying base flipping by M.TaqI and suggests similar quenching in the active sites of DNA and RNA adenine-N6 as well as DNA cytosine-N4 methyltransferases sharing the conserved motif IV. In solution, the same distinctive fluorescence response confirms complete destacking from DNA and is also observed when the proposed key residue for base flipping by M.TaqI, the target base partner thymine, is substituted by an abasic site analog. The corresponding cocrystal structure shows 2-aminopurine in the active site of M.TaqI, demonstrating that the partner thymine is not essential for base flipping. However, in this structure, a shift of the 3' neighbor of the target base into the vacancy left after base flipping is observed, apparently replicating a stabilizing role of the missing partner thymine. Time-resolved fluorescence and acrylamide quenching measurements of M.TaqI complexes in solution provide evidence for an alternative binding site for the extra-helical target base within M.TaqI and suggest that the partner thymine assists in delivering the target base into the active site.
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Affiliation(s)
- Thomas Lenz
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, D-52056 Aachen, Germany
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47
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Li J, Chorba JS, Whelan SPJ. Vesicular stomatitis viruses resistant to the methylase inhibitor sinefungin upregulate RNA synthesis and reveal mutations that affect mRNA cap methylation. J Virol 2007; 81:4104-15. [PMID: 17301155 PMCID: PMC1866143 DOI: 10.1128/jvi.02681-06] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Sinefungin (SIN), a natural S-adenosyl-L-methionine analog produced by Streptomyces griseolus, is a potent inhibitor of methyltransferases. We evaluated the effect of SIN on replication of vesicular stomatitis virus (VSV), a prototype of the nonsegmented negative-strand RNA viruses. The 241-kDa large polymerase (L) protein of VSV methylates viral mRNA cap structures at the guanine-N-7 (G-N-7) and ribose-2'-O (2'-O) positions. By performing transcription reactions in vitro, we show that both methylations are inhibited by SIN and that methylation was more sensitive at the G-N-7 than at 2'-O position. We further show that SIN inhibited growth of VSV in cell culture, reducing viral yield by 50-fold and diminishing plaque size. We isolated eight mutants that were resistant to SIN as judged by their growth characteristics. The SIN-resistant (SINR) viruses contained mutations in the L gene, the promoter for L gene expression provided by the conserved sequence elements of the G-L gene junction and the M gene. Five mutations resulted in amino acid substitutions to conserved regions II/III and VI of the L protein. For each mutant, we examined viral gene expression in cells and cap methylation in vitro. SINR mutants upregulated RNA synthesis in the presence of SIN, which may be responsible for their resistance. We also found that some SINR viruses with L gene mutations were defective in cap methylation in vitro, yet their methylases were less sensitive to SIN inhibition than those of the wild-type parent. These studies show that the VSV methylases are inhibited by SIN, and they define new regions of L protein that affect cap methylation. These studies also provide experimental evidence that inhibition of cap methylases is a potential strategy for development of antiviral therapeutics against nonsegmented negative-strand RNA viruses.
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Affiliation(s)
- Jianrong Li
- Harvard Medical School, Department of Microbiology and Molecular Genetics, 200 Longwood Ave., Boston, MA 02115, USA
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48
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Bheemanaik S, Reddy Y, Rao D. Structure, function and mechanism of exocyclic DNA methyltransferases. Biochem J 2006; 399:177-90. [PMID: 16987108 PMCID: PMC1609917 DOI: 10.1042/bj20060854] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
DNA MTases (methyltransferases) catalyse the transfer of methyl groups to DNA from AdoMet (S-adenosyl-L-methionine) producing AdoHcy (S-adenosyl-L-homocysteine) and methylated DNA. The C5 and N4 positions of cytosine and N6 position of adenine are the target sites for methylation. All three methylation patterns are found in prokaryotes, whereas cytosine at the C5 position is the only methylation reaction that is known to occur in eukaryotes. In general, MTases are two-domain proteins comprising one large and one small domain with the DNA-binding cleft located at the domain interface. The striking feature of all the structurally characterized DNA MTases is that they share a common core structure referred to as an 'AdoMet-dependent MTase fold'. DNA methylation has been reported to be essential for bacterial virulence, and it has been suggested that DNA adenine MTases (Dams) could be potential targets for both vaccines and antimicrobials. Drugs that block Dam could slow down bacterial growth and therefore drug-design initiatives could result in a whole new generation of antibiotics. The transfer of larger chemical entities in a MTase-catalysed reaction has been reported and this represents an interesting challenge for bio-organic chemists. In general, amino MTases could therefore be used as delivery systems for fluorescent or other reporter groups on to DNA. This is one of the potential applications of DNA MTases towards developing non-radioactive DNA probes and these could have interesting applications in molecular biology. Being nucleotide-sequence-specific, DNA MTases provide excellent model systems for studies on protein-DNA interactions. The focus of this review is on the chemistry, enzymology and structural aspects of exocyclic amino MTases.
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Affiliation(s)
| | - Yeturu V. R. Reddy
- Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India
| | - Desirazu N. Rao
- Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India
- To whom correspondence should be addressed (email )
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Zheng S, Hausmann S, Liu Q, Ghosh A, Schwer B, Lima CD, Shuman S. Mutational analysis of Encephalitozoon cuniculi mRNA cap (guanine-N7) methyltransferase, structure of the enzyme bound to sinefungin, and evidence that cap methyltransferase is the target of sinefungin's antifungal activity. J Biol Chem 2006; 281:35904-13. [PMID: 16971388 DOI: 10.1074/jbc.m607292200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cap (guanine-N7) methylation is an essential step in eukaryal mRNA synthesis and a potential target for antiviral, antifungal, and antiprotozoal drug discovery. Previous mutational and structural analyses of Encephalitozoon cuniculi Ecm1, a prototypal cellular cap methyltransferase, identified amino acids required for cap methylation in vivo, but also underscored the nonessentiality of many side chains that contact the cap and AdoMet substrates. Here we tested new mutations in residues that comprise the guanine-binding pocket, alone and in combination. The outcomes indicate that the shape of the guanine binding pocket is more crucial than particular base edge interactions, and they highlight the contributions of the aliphatic carbons of Phe-141 and Tyr-145 that engage in multiple van der Waals contacts with guanosine and S-adenosylmethionine (AdoMet), respectively. We purified 45 Ecm1 mutant proteins and assayed them for methylation of GpppA in vitro. Of the 21 mutations that resulted in unconditional lethality in vivo,14 reduced activity in vitro to < or = 2% of the wild-type level and 5 reduced methyltransferase activity to between 4 and 9% of wild-type Ecm1. The natural product antibiotic sinefungin is an AdoMet analog that inhibits Ecm1 with modest potency. The crystal structure of an Ecm1-sinefungin binary complex reveals sinefungin-specific polar contacts with main-chain and side-chain atoms that can explain the 3-fold higher affinity of Ecm1 for sinefungin versus AdoMet or S-adenosylhomocysteine (AdoHcy). In contrast, sinefungin is an extremely potent inhibitor of the yeast cap methyltransferase Abd1, to which sinefungin binds 900-fold more avidly than AdoHcy or AdoMet. We find that the sensitivity of Saccharomyces cerevisiae to growth inhibition by sinefungin is diminished when Abd1 is overexpressed. These results highlight cap methylation as a principal target of the antifungal activity of sinefungin.
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Affiliation(s)
- Sushuang Zheng
- Molecular Biology Program, Sloan-Kettering Institute, Weill College of Medicine of Cornell University, New York, New York 10021, USA
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50
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Watanabe M, Yuzawa H, Handa N, Kobayashi I. Hyperthermophilic DNA methyltransferase M.PabI from the archaeon Pyrococcus abyssi. Appl Environ Microbiol 2006; 72:5367-75. [PMID: 16885288 PMCID: PMC1538712 DOI: 10.1128/aem.00433-06] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2006] [Accepted: 05/08/2006] [Indexed: 12/31/2022] Open
Abstract
Genome sequence comparisons among multiple species of Pyrococcus, a hyperthermophilic archaeon, revealed a linkage between a putative restriction-modification gene complex and several large genome polymorphisms/rearrangements. From a region apparently inserted into the Pyrococcus abyssi genome, a hyperthermoresistant restriction enzyme [PabI; 5'-(GTA/C)] with a novel structure was discovered. In the present work, the neighboring methyltransferase homologue, M.PabI, was characterized. Its N-terminal half showed high similarities to the M subunit of type I systems and a modification enzyme of an atypical type II system, M.AhdI, while its C-terminal half showed high similarity to the S subunit of type I systems. M.PabI expressed within Escherichia coli protected PabI sites from RsaI, a PabI isoschizomer. M.PabI, purified following overexpression, was shown to generate 5'-GTm6AC, which provides protection against PabI digestion. M.PabI was found to be highly thermophilic; it showed methylation at 95 degrees C and retained at least half the activity after 9 min at 95 degrees C. This hyperthermophilicity allowed us to obtain activation energy and other thermodynamic parameters for the first time for any DNA methyltransferases. We also determined the kinetic parameters of kcat, Km, DNA, and Km, AdoMet. The activity of M.PabI was optimal at a slightly acidic pH and at an NaCl concentration of 200 to 500 mM and was inhibited by Zn2+ but not by Mg2+, Ca2+, or Mn2+. These and previous results suggest that this unique methyltransferase and PabI constitute a type II restriction-modification gene complex that inserted into the P. abyssi genome relatively recently. As the most thermophilic of all the characterized DNA methyltransferases, M.PabI may help in the analysis of DNA methylation and its application to DNA engineering.
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Affiliation(s)
- Miki Watanabe
- Laboratory of Social Genome Sciences, Department of Medical Genome Sciences, Graduate School of Frontier Sciences, University of Tokyo, Tokyo 108-8639, Japan
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