1
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Fukumoto Y, Kyono R, Shibukawa Y, Tanaka YK, Suzuki N, Ogra Y. Differential molecular mechanisms of substrate recognition by selenium methyltransferases, INMT and TPMT, in selenium detoxification and excretion. J Biol Chem 2024; 300:105599. [PMID: 38159853 PMCID: PMC10844679 DOI: 10.1016/j.jbc.2023.105599] [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: 09/15/2023] [Revised: 12/13/2023] [Accepted: 12/18/2023] [Indexed: 01/03/2024] Open
Abstract
It is known that the recommended dietary allowance of selenium (Se) is dangerously close to its tolerable upper intake level. Se is detoxified and excreted in urine as trimethylselenonium ion (TMSe) when the amount ingested exceeds the nutritional level. Recently, we demonstrated that the production of TMSe requires two methyltransferases: thiopurine S-methyltransferase (TPMT) and indolethylamine N-methyltransferase (INMT). In this study, we investigated the substrate recognition mechanisms of INMT and TPMT in the Se-methylation reaction. Examination of the Se-methyltransferase activities of two paralogs of INMT, namely, nicotinamide N-methyltransferase and phenylethanolamine N-methyltransferase, revealed that only INMT exhibited Se-methyltransferase activity. Consistently, molecular dynamics simulations demonstrated that dimethylselenide was preferentially associated with the active center of INMT. Using the fragment molecular orbital method, we identified hydrophobic residues involved in the binding of dimethylselenide to the active center of INMT. The INMT-L164R mutation resulted in a deficiency in Se- and N-methyltransferase activities. Similarly, TPMT-R152, which occupies the same position as INMT-L164, played a crucial role in the Se-methyltransferase activity of TPMT. Our findings suggest that TPMT recognizes negatively charged substrates, whereas INMT recognizes electrically neutral substrates in the hydrophobic active center embedded within the protein. These observations explain the sequential requirement of the two methyltransferases in producing TMSe.
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Affiliation(s)
- Yasunori Fukumoto
- Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan.
| | - Rin Kyono
- Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan
| | - Yuka Shibukawa
- Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan
| | - Yu-Ki Tanaka
- Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan
| | - Noriyuki Suzuki
- Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan
| | - Yasumitsu Ogra
- Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan
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2
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Neti SS, Wang B, Iwig DF, Onderko EL, Booker SJ. Enzymatic Fluoromethylation Enabled by the S-Adenosylmethionine Analog Te-Adenosyl- L-(fluoromethyl)homotellurocysteine. ACS CENTRAL SCIENCE 2023; 9:905-914. [PMID: 37252363 PMCID: PMC10214534 DOI: 10.1021/acscentsci.2c01385] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Indexed: 05/31/2023]
Abstract
Fluoromethyl, difluoromethyl, and trifluoromethyl groups are present in numerous pharmaceuticals and agrochemicals, where they play critical roles in the efficacy and metabolic stability of these molecules. Strategies for late-stage incorporation of fluorine-containing atoms in molecules have become an important area of organic and medicinal chemistry as well as synthetic biology. Herein, we describe the synthesis and use of Te-adenosyl-L-(fluoromethyl)homotellurocysteine (FMeTeSAM), a novel and biologically relevant fluoromethylating agent. FMeTeSAM is structurally and chemically related to the universal cellular methyl donor S-adenosyl-L-methionine (SAM) and supports the robust transfer of fluoromethyl groups to oxygen, nitrogen, sulfur, and some carbon nucleophiles. FMeTeSAM is also used to fluoromethylate precursors to oxaline and daunorubicin, two complex natural products that exhibit antitumor properties.
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Affiliation(s)
- Syam Sundar Neti
- Department
of Chemistry, Department of Biochemistry and Molecular Biology, and Howard Hughes
Medical Institute, The Pennsylvania State
University, University
Park, Pennsylvania 16802, United States
| | - Bo Wang
- Department
of Chemistry, Department of Biochemistry and Molecular Biology, and Howard Hughes
Medical Institute, The Pennsylvania State
University, University
Park, Pennsylvania 16802, United States
| | - David F. Iwig
- Department
of Chemistry, Department of Biochemistry and Molecular Biology, and Howard Hughes
Medical Institute, The Pennsylvania State
University, University
Park, Pennsylvania 16802, United States
| | - Elizabeth L. Onderko
- Department
of Chemistry, Department of Biochemistry and Molecular Biology, and Howard Hughes
Medical Institute, The Pennsylvania State
University, University
Park, Pennsylvania 16802, United States
| | - Squire J. Booker
- Department
of Chemistry, Department of Biochemistry and Molecular Biology, and Howard Hughes
Medical Institute, The Pennsylvania State
University, University
Park, Pennsylvania 16802, United States
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3
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Abdelraheem E, Thair B, Varela RF, Jockmann E, Popadić D, Hailes HC, Ward JM, Iribarren AM, Lewkowicz ES, Andexer JN, Hagedoorn PL, Hanefeld U. Methyltransferases, functions and applications. Chembiochem 2022; 23:e202200212. [PMID: 35691829 PMCID: PMC9539859 DOI: 10.1002/cbic.202200212] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 06/10/2022] [Indexed: 11/25/2022]
Abstract
In this review the current state‐of‐the‐art of S‐adenosylmethionine (SAM)‐dependent methyltransferases and SAM are evaluated. Their structural classification and diversity is introduced and key mechanistic aspects presented which are then detailed further. Then, catalytic SAM as a target for drugs, and approaches to utilise SAM as a cofactor in synthesis are introduced with different supply and regeneration approaches evaluated. The use of SAM analogues are also described. Finally O‐, N‐, C‐ and S‐MTs, their synthetic applications and potential for compound diversification is given.
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Affiliation(s)
| | - Benjamin Thair
- University College London Faculty of Mathematical and Physical Sciences, department of Chemistry, UNITED KINGDOM
| | - Romina Fernández Varela
- Universidad nacional di Quilmes, 3Laboratorio de Biotransformaciones y Química de Ácidos Nucleicos, ARGENTINA
| | - Emely Jockmann
- Albert-Ludwigs-Universitat Freiburg Universitatsbibliothek Freiburg, Pharmacie, GERMANY
| | | | - Helen C Hailes
- University College London Faculty of Mathematical and Physical Sciences, department of Chemistry, UNITED KINGDOM
| | - John M Ward
- University College London, Department of Biochemical Engineering, UNITED KINGDOM
| | - Adolfo M Iribarren
- Universidad Nacional de Quilmes, 3Laboratorio de Biotransformaciones y Química de Ácidos Nucleicos, ARGENTINA
| | - Elizabeth S Lewkowicz
- Universidad Nacional de Quilmes, Laboratorio de Biotransformaciones y Química de Ácidos Nucleicos, ARGENTINA
| | | | | | - Ulf Hanefeld
- Technische Universiteit Delft, Gebouw voor Scheikunde, Julianalaan 136, 2628 BL, Delft, NETHERLANDS
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4
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Li C, Crack JC, Newton‐Payne S, Murphy ARJ, Chen X, Pinchbeck BJ, Zhou S, Williams BT, Peng M, Zhang X, Chen Y, Le Brun NE, Todd JD, Zhang Y. Mechanistic insights into the key marine dimethylsulfoniopropionate synthesis enzyme DsyB/DSYB. MLIFE 2022; 1:114-130. [PMID: 38817677 PMCID: PMC10989797 DOI: 10.1002/mlf2.12030] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 05/13/2022] [Accepted: 05/17/2022] [Indexed: 06/01/2024]
Abstract
Marine algae and bacteria produce approximately eight billion tonnes of the organosulfur molecule dimethylsulfoniopropionate (DMSP) in Earth's surface oceans annually. DMSP is an antistress compound and, once released into the environment, a major nutrient, signaling molecule, and source of climate-active gases. The methionine transamination pathway for DMSP synthesis is used by most known DMSP-producing algae and bacteria. The S-directed S-adenosylmethionine (SAM)-dependent 4-methylthio-2-hydroxybutyrate (MTHB) S-methyltransferase, encoded by the dsyB/DSYB gene, is the key enzyme of this pathway, generating S-adenosylhomocysteine (SAH) and 4-dimethylsulfonio-2-hydroxybutyrate (DMSHB). DsyB/DSYB, present in most haptophyte and dinoflagellate algae with the highest known intracellular DMSP concentrations, is shown to be far more abundant and transcribed in marine environments than any other known S-methyltransferase gene in DMSP synthesis pathways. Furthermore, we demonstrate in vitro activity of the bacterial DsyB enzyme from Nisaea denitrificans and provide its crystal structure in complex with SAM and SAH-MTHB, which together provide the first important mechanistic insights into a DMSP synthesis enzyme. Structural and mutational analyses imply that DsyB adopts a proximity and desolvation mechanism for the methyl transfer reaction. Sequence analysis suggests that this mechanism may be common to all bacterial DsyB enzymes and also, importantly, eukaryotic DSYB enzymes from e.g., algae that are the major DMSP producers in Earth's surface oceans.
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Affiliation(s)
- Chun‐Yang Li
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, College of Marine Life SciencesOcean University of ChinaQingdaoChina
- State Key Laboratory of Microbial TechnologyMarine Biotechnology Research Center, Shandong UniversityQingdaoChina
- Laboratory for Marine Biology and BiotechnologyPilot National Laboratory for Marine Science and TechnologyQingdaoShandongChina
| | - Jason C. Crack
- School of Chemistry, Centre for Molecular and Structural BiochemistryUniversity of East Anglia, Norwich Research ParkNorwichUK
| | | | | | - Xiu‐Lan Chen
- State Key Laboratory of Microbial TechnologyMarine Biotechnology Research Center, Shandong UniversityQingdaoChina
- Laboratory for Marine Biology and BiotechnologyPilot National Laboratory for Marine Science and TechnologyQingdaoShandongChina
| | | | - Shun Zhou
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, College of Marine Life SciencesOcean University of ChinaQingdaoChina
- School of Biological SciencesUniversity of East AngliaNorwichUK
| | | | - Ming Peng
- State Key Laboratory of Microbial TechnologyMarine Biotechnology Research Center, Shandong UniversityQingdaoChina
| | - Xiao‐Hua Zhang
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, College of Marine Life SciencesOcean University of ChinaQingdaoChina
| | - Yin Chen
- School of Life SciencesUniversity of WarwickCoventryUK
| | - Nick E. Le Brun
- School of Chemistry, Centre for Molecular and Structural BiochemistryUniversity of East Anglia, Norwich Research ParkNorwichUK
| | - Jonathan D. Todd
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, College of Marine Life SciencesOcean University of ChinaQingdaoChina
- School of Biological SciencesUniversity of East AngliaNorwichUK
| | - Yu‐Zhong Zhang
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, College of Marine Life SciencesOcean University of ChinaQingdaoChina
- State Key Laboratory of Microbial TechnologyMarine Biotechnology Research Center, Shandong UniversityQingdaoChina
- Laboratory for Marine Biology and BiotechnologyPilot National Laboratory for Marine Science and TechnologyQingdaoShandongChina
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5
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Insights into methionine S-methylation in diverse organisms. Nat Commun 2022; 13:2947. [PMID: 35618717 PMCID: PMC9135737 DOI: 10.1038/s41467-022-30491-5] [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: 01/19/2021] [Accepted: 05/02/2022] [Indexed: 12/04/2022] Open
Abstract
Dimethylsulfoniopropionate (DMSP) is an important marine anti-stress compound, with key roles in global nutrient cycling, chemotaxis and, potentially, climate regulation. Recently, diverse marine Actinobacteria, α- and γ-proteobacteria were shown to initiate DMSP synthesis via the methionine (Met) S-methyltransferase enzyme (MmtN), generating S-methyl-Met (SMM). Here we characterize a roseobacterial MmtN, providing structural and mechanistic insights into this DMSP synthesis enzyme. We propose that MmtN uses the proximity and desolvation mechanism for Met S-methylation with two adjacent MmtN monomers comprising the Met binding site. We also identify diverse functional MmtN enzymes in potentially symbiotic archaeal Candidatus Woesearchaeota and Candidate Phyla Radiation (CPR) bacteria, and the animalcule Adineta steineri, not anticipated to produce SMM and/or DMSP. These diverse MmtN enzymes, alongside the larger plant MMT enzyme with an N-terminus homologous to MmtN, likely utilize the same proximity and desolvation mechanism. This study provides important insights into the catalytic mechanism of SMM and/or DMSP production, and proposes roles for these compounds in secondary metabolite production, and SMM cycling in diverse organisms and environments. S-methyl methionine (SMM) is a key molecule in production of dimethylsulfoniopropionate (DMSP), an important marine anti-stress compound, with roles in global nutrient cycling. Here, the authors determine the mechanism of SMM synthesis and uncover unexpected roles for SMM in archaea, CPR bacteria and animals.
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6
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Franca R, Braidotti S, Stocco G, Decorti G. Understanding thiopurine methyltransferase polymorphisms for the targeted treatment of hematologic malignancies. Expert Opin Drug Metab Toxicol 2021; 17:1187-1198. [PMID: 34452592 DOI: 10.1080/17425255.2021.1974398] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
INTRODUCTION Thiopurine methyltransferase (TPMT) catalyzes the S-methylation of thiopurines (mercaptopurine (MP) and tioguanine (TG)), chemotherapeutic agents used in the treatment of acute lymphoblastic leukemia (ALL). Polymorphisms in TPMT gene encode diminished activity enzyme, enhancing accumulation of active metabolites, and partially explaining the inter-individual differences in patients' clinical response. AREAS COVERED This review gives an overview on TPMT gene and function, and discusses the pharmacogenomic implications of TPMT variants in the prevention of severe thiopurine-induced hematological toxicities and the less known implication on TG-induced sinusoidal obstruction syndrome. Additional genetic and non-genetic factors impairing TPMT activity are considered. Literature search was done in PubMed for English articles published since1990, and on PharmGKB. EXPERT OPINION To titrate thiopurines safely and effectively, achieve the right degree of lymphotoxic effect and avoid excessive myelosuppression, the optimal management will combine a preemptive TPMT genotyping to establish a safe initial dose with a close phenotypic monitoring of TPMT activity and/or of active metabolites during long-term treatment. Compared to current ALL protocols, replacement of TG by MP during reinduction phase in TPMT heterozygotes and novel individualized TG regimens in maintenance for TPMT wild-type subjects could be investigated to improve outcomes while avoiding risk of severe hepatotoxicity.
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Affiliation(s)
- R Franca
- Department of Medical, Surgical and Health Sciences, University of Trieste, Trieste, Italy
| | - S Braidotti
- Department of Medical, Surgical and Health Sciences, University of Trieste, Trieste, Italy
| | - G Stocco
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | - G Decorti
- Department of Medical, Surgical and Health Sciences, University of Trieste, Trieste, Italy.,Institute for Maternal & Child Health (I.r.c.c.s) Burlo Garofolo, Trieste, Italy
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7
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Tang Q, Pavlidis IV, Badenhorst CPS, Bornscheuer UT. From Natural Methylation to Versatile Alkylations Using Halide Methyltransferases. Chembiochem 2021; 22:2584-2590. [PMID: 33890381 PMCID: PMC8453949 DOI: 10.1002/cbic.202100153] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 04/22/2021] [Indexed: 11/06/2022]
Abstract
Halide methyltransferases (HMTs) enable the enzymatic synthesis of S-adenosyl-l-methionine (SAM) from S-adenosyl-l-homocysteine (SAH) and methyl iodide. Characterisation of a range of naturally occurring HMTs and subsequent protein engineering led to HMT variants capable of synthesising ethyl, propyl, and allyl analogues of SAM. Notably, HMTs do not depend on chemical synthesis of methionine analogues, as required by methionine adenosyltransferases (MATs). However, at the moment MATs have a much broader substrate scope than the HMTs. Herein we provide an overview of the discovery and engineering of promiscuous HMTs and how these strategies will pave the way towards a toolbox of HMT variants for versatile chemo- and regioselective biocatalytic alkylations.
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Affiliation(s)
- Qingyun Tang
- Institute of BiochemistryUniversity of GreifswaldFelix-Hausdorff-Str. 417489GreifswaldGermany
| | - Ioannis V. Pavlidis
- Dept. of ChemistryUniversity of CreteVoutes University Campus70013HeraklionGreece
| | | | - Uwe T. Bornscheuer
- Institute of BiochemistryUniversity of GreifswaldFelix-Hausdorff-Str. 417489GreifswaldGermany
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8
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Ha C, Kim ES, Kwon Y, Choe YH, Kim MJ, Lee SY. The Identification of a Novel Thiopurine S-Methyltransferase Allele, TPMT*45, in Korean Patient with Crohn's Disease. PHARMACOGENOMICS & PERSONALIZED MEDICINE 2020; 13:665-671. [PMID: 33273844 PMCID: PMC7705256 DOI: 10.2147/pgpm.s279446] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Accepted: 11/11/2020] [Indexed: 01/08/2023]
Abstract
Pediatric Crohn’s disease (CD) carries a higher genetic susceptibility and an increased risk of a more aggressive disease course than adult CD. Treatment of CD is based on immunomodulatory drugs, such as thiopurines. The enzyme mainly involved in drug metabolism is thiopurine S-methyltransferase (TPMT). An increased concentration of drug metabolites can cause adverse drug effects, such as myelosuppression and hepatotoxicity; therefore, assessing the activity of TPMT is essential both before and during treatment. TPMT genotyping result is not affected by previous thiopurine dose and currently is the primary component of TPMT activity and disease monitoring. Until now, more than 40 allelic variants of the TPMT gene have been reported, with most of them having an uncertain or no enzyme function. In this article, we report the first case of a novel TPMT allele, TPMT*45, that was identified in a Korean girl with CD whose findings suggested decreased TPMT activity. This newly observed variant is caused by a single nucleotide polymorphism resulting in nonsense mutation (c.676C>T, p.R226*) and the partial loss of amino acids in the TPMT protein. Initially, the patient began azathioprine at a standard dosage (1.5 mg/kg/day), and her laboratory results, including red blood cell (RBC) TPMT activity (6-methylmercaptopurine 2.68 nmol/mL/h and 6-methylmercaptopurine riboside 4.82 nmol/mL/h) along with thiopurine metabolite levels (6-thioguanine nucleotides 479.3 pmol/8×108 RBC), suggested an enzyme deficiency. The thiopurine dose was reduced to half (0.7 mg/kg/day), and the follow-up metabolite results as well as the associated inflammatory markers were continuously within reference ranges. Along with an improvement in the patient’s subjective reports and clinical symptoms, the patient demonstrated a good treatment response to the adjusted dose. The results of our report illustrate the importance of TPMT genotyping and pharmacogenetic-based thiopurine dose adjustment. Further research should focus on the functional characterization and impact on this novel allele’s treatment effect.
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Affiliation(s)
- Changhee Ha
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Eun Sil Kim
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Yiyoung Kwon
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Yon Ho Choe
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Mi Jin Kim
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Soo-Youn Lee
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.,Department of Clinical Pharmacology and Therapeutics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
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9
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Fukumoto Y, Yamada H, Matsuhashi K, Okada W, Tanaka YK, Suzuki N, Ogra Y. Production of a Urinary Selenium Metabolite, Trimethylselenonium, by Thiopurine S-Methyltransferase and Indolethylamine N-Methyltransferase. Chem Res Toxicol 2020; 33:2467-2474. [DOI: 10.1021/acs.chemrestox.0c00254] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Yasunori Fukumoto
- Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo, Chiba 260-8675, Japan
| | - Hirotaka Yamada
- Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo, Chiba 260-8675, Japan
| | - Kemmu Matsuhashi
- Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo, Chiba 260-8675, Japan
| | - Wakaba Okada
- Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo, Chiba 260-8675, Japan
| | - Yu-ki Tanaka
- Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo, Chiba 260-8675, Japan
| | - Noriyuki Suzuki
- Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo, Chiba 260-8675, Japan
| | - Yasumitsu Ogra
- Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo, Chiba 260-8675, Japan
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10
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Policarpo RL, Decultot L, May E, Kuzmič P, Carlson S, Huang D, Chu V, Wright BA, Dhakshinamoorthy S, Kannt A, Rani S, Dittakavi S, Panarese JD, Gaudet R, Shair MD. High-Affinity Alkynyl Bisubstrate Inhibitors of Nicotinamide N-Methyltransferase (NNMT). J Med Chem 2019; 62:9837-9873. [PMID: 31589440 DOI: 10.1021/acs.jmedchem.9b01238] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Nicotinamide N-methyltransferase (NNMT) is a metabolic enzyme that methylates nicotinamide (NAM) using cofactor S-adenosylmethionine (SAM). NNMT overexpression has been linked to diabetes, obesity, and various cancers. In this work, structure-based rational design led to the development of potent and selective alkynyl bisubstrate inhibitors of NNMT. The reported nicotinamide-SAM conjugate (named NS1) features an alkyne as a key design element that closely mimics the linear, 180° transition state geometry found in the NNMT-catalyzed SAM → NAM methyl transfer reaction. NS1 was synthesized in 14 steps and found to be a high-affinity, subnanomolar NNMT inhibitor. An X-ray cocrystal structure and SAR study revealed the ability of an alkynyl linker to span the methyl transfer tunnel of NNMT with ideal shape complementarity. The compounds reported in this work represent the most potent and selective NNMT inhibitors reported to date. The rational design principle described herein could potentially be extended to other methyltransferase enzymes.
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Affiliation(s)
| | | | | | - Petr Kuzmič
- BioKin Ltd. , Watertown , Massachusetts 02472 , United States
| | | | | | | | | | | | - Aimo Kannt
- Sanofi Research and Development , Industriepark Hoechst, H823 , D-65926 Frankfurt am Main , Germany
| | - Shilpa Rani
- Jubilant Biosys Ltd. , Yeshwantpur, Bangalore , 560 022 Karnataka , India
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11
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Methylation of selenocysteine catalysed by thiopurine S-methyltransferase. Biochim Biophys Acta Gen Subj 2018; 1863:182-190. [PMID: 30308221 DOI: 10.1016/j.bbagen.2018.10.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 08/25/2018] [Accepted: 10/02/2018] [Indexed: 12/16/2022]
Abstract
BACKGROUND Methylation driven by thiopurine S-methylatransferase (TPMT) is crucial for deactivation of cytostatic and immunosuppressant thiopurines. Despite its remarkable integration into clinical practice, the endogenous function of TPMT is unknown. METHODS To address the role of TPMT in methylation of selenium compounds, we established the research on saturation transfer difference (STD) and 77Se NMR spectroscopy, fluorescence measurements, as well as computational molecular docking simulations. RESULTS Using STD NMR spectroscopy and fluorescence measurements of tryptophan residues in TPMT, we determined the binding of selenocysteine (Sec) to human recombinant TPMT. By comparing binding characteristics of Sec in the absence and in the presence of methyl donor, we confirmed S-adenosylmethionine (SAM)-induced conformational changes in TPMT. Molecular docking analysis positioned Sec into the active site of TPMT with orientation relevant for methylation reaction. Se-methylselenocysteine (MeSec), produced in the enzymatic reaction, was detected by 77Se NMR spectroscopy. A direct interaction between Sec and SAM in the active site of rTPMT and the formation of both products, MeSec and S-adenosylhomocysteine, was demonstrated using NMR spectroscopy. CONCLUSIONS The present study provides evidence on in vitro methylation of Sec by rTPMT in a SAM-dependant manner. GENERAL SIGNIFICANCE Our results suggest novel role of TPMT and demonstrate new insights into enzymatic modifications of the 21st amino acid.
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12
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Wennerstrand P, Blissing A, Mårtensson LG. In Vitro Protein Stability of Two Naturally Occurring Thiopurine S-Methyltransferase Variants: Biophysical Characterization of TPMT*6 and TPMT*8. ACS OMEGA 2017; 2:4991-4999. [PMID: 30023734 PMCID: PMC6044926 DOI: 10.1021/acsomega.7b00801] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Accepted: 07/18/2017] [Indexed: 06/02/2023]
Abstract
Thiopurine S-methyltransferase (TPMT) is a polymorphic enzyme involved in the metabolism and inactivation of thiopurine substances administered as immunosuppressants in the treatment of malignancies and autoimmune diseases. In this study, the naturally occurring variants, TPMT*6 (Y180F) and TPMT*8 (R215H), have been biophysically characterized. Despite being classified as low and intermediate in vivo enzyme activity variants, respectively, our results demonstrate a discrepancy because both TPMT*6 and TPMT*8 were found to exhibit normal functionality in vitro. While TPMT*8 exhibited biophysical properties almost indistinguishable from those of TPMTwt, the TPMT*6 variant was found to be destabilized. Furthermore, the contributions of the cofactor S-adenosylmethionine (SAM) to the thermodynamic stability of TPMT were investigated, but only a modest stabilizing effect was observed. Also presented herein is a new method for studies of the biophysical characteristics of TPMT and its variants using the extrinsic fluorescent probe 8-anilinonaphthalene-1-sulfonic acid (ANS). ANS was found to bind strongly to all investigated TPMT variants with a Kd of approximately 0.2 μM and a 1:1 binding ratio as determined by isothermal titration calorimetry (ITC). Circular dichroism and fluorescence measurements showed that ANS binds exclusively to the native state of TPMT, and binding to the active site was confirmed by molecular modeling and simulated docking as well as ITC measurements. The strong binding of the probe to native TPMT and the conformity of the obtained results demonstrate the advantages of using ANS binding characteristics in studies of this protein and its variants.
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13
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Mei S, Li X, Gong X, Zhang X, Li X, Yang L, Zhu L, Zhou H, Liu Y, Zhou A, Zhang X, Zhao Z. Comparison of 6-mercaptopurine with 6-thioguanine for the analysis of thiopurine S-methyltransferase activity in human erythrocyte by LC-MS/MS. Biomed Chromatogr 2017; 31. [PMID: 28212467 DOI: 10.1002/bmc.3959] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2016] [Revised: 01/25/2017] [Accepted: 02/11/2017] [Indexed: 11/05/2022]
Abstract
Thiopurines (TPDs) are first-line drugs in treating neuromyelitis optica spectrum disorders (NMOSD). Evaluation of thiopurine S-methyltransferase activity (TPMT), a major determinant of TPD toxicity, before TPD treatment using 6-mercaptopurine (6-MP) and 6-thioguanine (6-TG) as substrate was suggested. However, the equivalent of the two substrates in TPMT activity evaluation was unknown, and an alternative substrate was required in TPMT activity evaluation in patients who were already taking 6-MP or 6-TG. Before evaluating the agreement of 6-MP and 6-TG in TPMT activity measurement in patients with NMOSD, the affinity of the two substrates for the active center of TPMT should be established. A computer-based simulation indicated that 6-MP and 6-TG had similar affinities for the two active sites of TPMT. According to the guidelines, an LC-MS/MS method was developed and validated to evaluate the TPMT activity in human erythrocyte hemolysate using 6-MP or 6-TG as substrates via 1 h incubation at 37°C. The method was applied in 81 patients with NMOSD. Evaluated by Bland-Altman plot, 6-methylmercaptopurine and 6-methylthioguanine represented TPMT activities were in agreement with each other. Further studies are warranted to confirm the results.
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Affiliation(s)
- Shenghui Mei
- Department of Pharmacy, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China.,Department of Clinical Pharmacology, College of Pharmaceutical Sciences, Capital Medical University, Beijing, People's Republic of China
| | - Xindi Li
- Neuroinfection and Neuroimmunology Center, Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China.,China National Clinical Research Center for Neurological Diseases, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China
| | - Xiaoqing Gong
- Neuroinfection and Neuroimmunology Center, Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China.,China National Clinical Research Center for Neurological Diseases, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China
| | - Xiaoyi Zhang
- College of Pharmaceutical Sciences, Capital Medical University, Beijing, People's Republic of China
| | - Xingang Li
- Department of Pharmacy, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China.,Department of Clinical Pharmacology, College of Pharmaceutical Sciences, Capital Medical University, Beijing, People's Republic of China
| | - Li Yang
- Department of Pharmacy, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China.,Department of Clinical Pharmacology, College of Pharmaceutical Sciences, Capital Medical University, Beijing, People's Republic of China
| | - Leting Zhu
- Department of Pharmacy, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China
| | - Heng Zhou
- Neuroinfection and Neuroimmunology Center, Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China.,China National Clinical Research Center for Neurological Diseases, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China
| | - Yonghong Liu
- Neuroinfection and Neuroimmunology Center, Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China.,China National Clinical Research Center for Neurological Diseases, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China
| | - Anna Zhou
- Neuroinfection and Neuroimmunology Center, Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China.,China National Clinical Research Center for Neurological Diseases, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China
| | - Xinghu Zhang
- Neuroinfection and Neuroimmunology Center, Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China.,China National Clinical Research Center for Neurological Diseases, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China
| | - Zhigang Zhao
- Department of Pharmacy, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China
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Structural Analysis of Glycine Sarcosine N-methyltransferase from Methanohalophilus portucalensis Reveals Mechanistic Insights into the Regulation of Methyltransferase Activity. Sci Rep 2016; 6:38071. [PMID: 27934872 PMCID: PMC5146677 DOI: 10.1038/srep38071] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 11/04/2016] [Indexed: 12/22/2022] Open
Abstract
Methyltransferases play crucial roles in many cellular processes, and various regulatory mechanisms have evolved to control their activities. For methyltransferases involved in biosynthetic pathways, regulation via feedback inhibition is a commonly employed strategy to prevent excessive accumulation of the pathways’ end products. To date, no biosynthetic methyltransferases have been characterized by X-ray crystallography in complex with their corresponding end product. Here, we report the crystal structures of the glycine sarcosine N-methyltransferase from the halophilic archaeon Methanohalophilus portucalensis (MpGSMT), which represents the first structural elucidation of the GSMT methyltransferase family. As the first enzyme in the biosynthetic pathway of the osmoprotectant betaine, MpGSMT catalyzes N-methylation of glycine and sarcosine, and its activity is feedback-inhibited by the end product betaine. A structural analysis revealed that, despite the simultaneous presence of both substrate (sarcosine) and cofactor (S-adenosyl-L-homocysteine; SAH), the enzyme was likely crystallized in an inactive conformation, as additional structural changes are required to complete the active site assembly. Consistent with this interpretation, the bound SAH can be replaced by the methyl donor S-adenosyl-L-methionine without triggering the methylation reaction. Furthermore, the observed conformational state was found to harbor a betaine-binding site, suggesting that betaine may inhibit MpGSMT activity by trapping the enzyme in an inactive form. This work implicates a structural basis by which feedback inhibition of biosynthetic methyltransferases may be achieved.
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15
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Duell ER, Glaser M, Le Chapelain C, Antes I, Groll M, Huber EM. Sequential Inactivation of Gliotoxin by the S-Methyltransferase TmtA. ACS Chem Biol 2016; 11:1082-9. [PMID: 26808594 DOI: 10.1021/acschembio.5b00905] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The epipolythiodioxopiperazine (ETP) gliotoxin mediates toxicity via its reactive thiol groups and thereby contributes to virulence of the human pathogenic fungus Aspergillus fumigatus. Self-intoxication of the mold is prevented either by reversible oxidation of reduced gliotoxin or by irreversible conversion to bis(methylthio)gliotoxin. The latter is produced by the S-methyltransferase TmtA and attenuates ETP biosynthesis. Here, we report the crystal structure of TmtA in complex with S-(5'-adenosyl)-l-homocysteine. TmtA features one substrate and one cofactor binding pocket per protein, and thus, bis-thiomethylation of gliotoxin occurs sequentially. Molecular docking of substrates and products into the active site of TmtA reveals that gliotoxin forms specific interactions with the protein surroundings, and free energy calculations indicate that methylation of the C10a-SH group precedes alkylation of the C3-SH site. Altogether, TmtA is well suited to selectively convert gliotoxin and to control its biosynthesis, suggesting that homologous enzymes serve to regulate the production of their toxic natural sulfur compounds in a similar manner.
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Affiliation(s)
- Elke R. Duell
- Center for Integrated Protein
Science Munich (CIPSM) at the Department Chemie, Technische Universität München, Lichtenbergstr. 4, 85748 Garching, Germany
| | - Manuel Glaser
- Center for Integrated Protein
Science Munich (CIPSM) at the Department Chemie, Technische Universität München, Lichtenbergstr. 4, 85748 Garching, Germany
| | - Camille Le Chapelain
- Center for Integrated Protein
Science Munich (CIPSM) at the Department Chemie, Technische Universität München, Lichtenbergstr. 4, 85748 Garching, Germany
| | - Iris Antes
- Center for Integrated Protein
Science Munich (CIPSM) at the Department Chemie, Technische Universität München, Lichtenbergstr. 4, 85748 Garching, Germany
| | - Michael Groll
- Center for Integrated Protein
Science Munich (CIPSM) at the Department Chemie, Technische Universität München, Lichtenbergstr. 4, 85748 Garching, Germany
| | - Eva M. Huber
- Center for Integrated Protein
Science Munich (CIPSM) at the Department Chemie, Technische Universität München, Lichtenbergstr. 4, 85748 Garching, Germany
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16
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Revollo J, Petibone DM, McKinzie P, Knox B, Morris SM, Ning B, Dobrovolsky VN. Whole genome and normalized mRNA sequencing reveal genetic status of TK6, WTK1, and NH32 human B-lymphoblastoid cell lines. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2015; 795:60-9. [PMID: 26774668 DOI: 10.1016/j.mrgentox.2015.11.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 11/12/2015] [Accepted: 11/14/2015] [Indexed: 01/05/2023]
Abstract
Closely related TK6, WTK1, and NH32 human B-lymphoblastoid cell lines differ in their p53 functional status. These lines are used frequently in genotoxicity studies and in studies aimed at understanding the role of p53 in DNA repair. Despite their routine use, little is known about the genetic status of these cells. To provide insight into their genetic composition, we sequenced and analyzed the entire genome of TK6 cells, as well as the normalized transcriptomes of TK6, WTK1, and NH32 cells. Whole genome sequencing (WGS) identified 21,561 genes and 5.17×10(6) small variants. Within the small variants, 50.54% were naturally occurring single nucleotide polymorphisms (SNPs) and 49.46% were mutations. The mutations were comprised of 92.97% single base-pair substitutions and 7.03% insertions or deletions (indels). The number of predicted genes, SNPs, and small mutations are similar to frequencies observed in the human population in general. Normalized mRNA-seq analysis identified the expression of transcripts bearing SNPs or mutations for TK6, WTK1, and NH32 as 2.88%, 2.04%, and 1.71%, respectively, and several of the variant transcripts identified appear to have important implications in genetic toxicology. These include a single base deletion mutation in the ferritin heavy chain gene (FTH1) resulting in a frame shift and protein truncation in TK6 that impairs iron metabolism. SNPs in the thiopurine S-methyltransferase (TPMT) gene (TPMT*3A SNP), and in the xenobiotic metabolizing enzyme, NADPH quinine oxidoreductase 1 (NQO1) gene (NQO1*2 SNP), are both associated with decreased enzyme activity. The clinically relevant TPMT*3A and NQO1*2 SNPs can make these cell lines useful in pharmacogenetic studies aimed at improving or tailoring drug treatment regimens that minimize toxicity and enhance efficacy.
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Affiliation(s)
- Javier Revollo
- Division of Genetic and Molecular Toxicology, FDA/NCTR, Jefferson, AR 72079, United States
| | - Dayton M Petibone
- Division of Genetic and Molecular Toxicology, FDA/NCTR, Jefferson, AR 72079, United States.
| | - Page McKinzie
- Division of Genetic and Molecular Toxicology, FDA/NCTR, Jefferson, AR 72079, United States
| | - Bridgett Knox
- Division of Systems Biology, FDA/NCTR, Jefferson, AR 72079, United States
| | - Suzanne M Morris
- Division of Genetic and Molecular Toxicology, FDA/NCTR, Jefferson, AR 72079, United States
| | - Baitang Ning
- Division of Systems Biology, FDA/NCTR, Jefferson, AR 72079, United States
| | - Vasily N Dobrovolsky
- Division of Genetic and Molecular Toxicology, FDA/NCTR, Jefferson, AR 72079, United States
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17
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Fazel-Najafabadi E, Vahdat Ahar E, Fattahpour S, Sedghi M. Structural and functional impact of missense mutations in TPMT: An integrated computational approach. Comput Biol Chem 2015; 59 Pt A:48-55. [PMID: 26410243 DOI: 10.1016/j.compbiolchem.2015.09.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2015] [Revised: 08/17/2015] [Accepted: 09/06/2015] [Indexed: 11/26/2022]
Abstract
BACKGROUND Thiopurine S-methyltransferase (TPMT) detoxifies thiopurine drugs which are used for treatment of various diseases including inflammatory bowel disease (IBD), and hematological malignancies. Individual variation in TPMT activity results from mutations in TPMT gene. In this study, the effects of all the known missense mutations in TPMT enzyme were studied at the sequence and structural level METHODS A broad set of bioinformatic tools was used to assess all the known missense mutations affecting enzyme activity. The effects of these mutations on protein stability, aggregation propensity, and residue interaction network were analyzed. RESULTS Our results indicate that the missense mutations have diverse effects on TPMT structure and function. Stability and aggregation propensities are affected by various mutations. Several mutations also affect residues in ligand binding site. CONCLUSIONS In vitro study of missense mutation is laborious and time-consuming. However, computational methods can be used to obtain information about effects of missense mutations on protein structure. In this study, the effects of most of the mutations on enzyme activity could be explained by computational methods. Thus, the present approach can be used for understanding the protein structure-function relationships.
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Affiliation(s)
- Esmat Fazel-Najafabadi
- Medical Genetics Laboratory, Alzahra University Hospital, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Elham Vahdat Ahar
- Institute of Biochemistry and Biophysics, University of Tehran, Iran
| | - Shirin Fattahpour
- Medical Genetics Laboratory, Alzahra University Hospital, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Maryam Sedghi
- Medical Genetics Laboratory, Alzahra University Hospital, Isfahan University of Medical Sciences, Isfahan, Iran; Pediatric Inherited Diseases Research Center, Research Institute for Primordial Prevention of Non-communicable disease, Isfahan University of Medical Sciences, Isfahan, Iran.
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18
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Dolan S, Owens R, O’Keeffe G, Hammel S, Fitzpatrick D, Jones G, Doyle S. Regulation of Nonribosomal Peptide Synthesis: bis-Thiomethylation Attenuates Gliotoxin Biosynthesis in Aspergillus fumigatus. ACTA ACUST UNITED AC 2014; 21:999-1012. [DOI: 10.1016/j.chembiol.2014.07.006] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 07/09/2014] [Accepted: 07/21/2014] [Indexed: 01/30/2023]
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19
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Liscombe DK, Louie GV, Noel JP. Architectures, mechanisms and molecular evolution of natural product methyltransferases. Nat Prod Rep 2012; 29:1238-50. [PMID: 22850796 DOI: 10.1039/c2np20029e] [Citation(s) in RCA: 202] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The addition of a methyl moiety to a small chemical is a common transformation in the biosynthesis of natural products across all three domains of life. These methylation reactions are most often catalysed by S-adenosyl-L-methionine (SAM)-dependent methyltransferases (MTs). MTs are categorized based on the electron-rich, methyl accepting atom, usually O, N, C, or S. SAM-dependent natural product MTs (NPMTs) are responsible for the modification of a wide array of structurally distinct substrates, including signalling and host defense compounds, pigments, prosthetic groups, cofactors, cell membrane and cell wall components, and xenobiotics. Most notably, methylation modulates the bioavailability, bioactivity, and reactivity of acceptor molecules, and thus exerts a central role on the functional output of many metabolic pathways. Our current understanding of the structural enzymology of NPMTs groups these phylogenetically diverse enzymes into two MT-superfamily fold classes (class I and class III). Structural biology has also shed light on the catalytic mechanisms and molecular bases for substrate specificity for over fifty NPMTs. These biophysical-based approaches have contributed to our understanding of NPMT evolution, demonstrating how a widespread protein fold evolved to accommodate chemically diverse methyl acceptors and to catalyse disparate mechanisms suited to the physiochemical properties of the target substrates. This evolutionary diversity suggests that NPMTs may serve as starting points for generating new biocatalysts.
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Affiliation(s)
- David K Liscombe
- Howard Hughes Medical Institute, Jack H. Skirball Center for Chemical Biology and Proteomics, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
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20
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Wennerstrand P, Dametto P, Hennig J, Klingstedt T, Skoglund K, Lindqvist Appell M, Mårtensson LG. Structural Characteristics Determine the Cause of the Low Enzyme Activity of Two Thiopurine S-Methyltransferase Allelic Variants: A Biophysical Characterization of TPMT*2 and TPMT*5. Biochemistry 2012; 51:5912-20. [DOI: 10.1021/bi300377d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Patricia Wennerstrand
- Department of Physics, Chemistry,
and Biology, Linköping University, SE-581 83 Linköping, Sweden
| | - Paolo Dametto
- Department of Physics, Chemistry,
and Biology, Linköping University, SE-581 83 Linköping, Sweden
| | - Janosch Hennig
- Division of Molecular Biotechnology, Department of Physics, Chemistry,
and Biology, Linköping University, SE-581 83 Linköping, Sweden
| | - Therése Klingstedt
- Department of Physics, Chemistry,
and Biology, Linköping University, SE-581 83 Linköping, Sweden
| | - Karin Skoglund
- Division of Drug Research/Clinical Pharmacology, Department of Medical
and Health Sciences, Faculty of Health Sciences, Linköping University, SE-581 83 Linköping, Sweden
| | - Malin Lindqvist Appell
- Division of Drug Research/Clinical Pharmacology, Department of Medical
and Health Sciences, Faculty of Health Sciences, Linköping University, SE-581 83 Linköping, Sweden
| | - Lars-Göran Mårtensson
- Department of Physics, Chemistry,
and Biology, Linköping University, SE-581 83 Linköping, Sweden
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21
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Pan XL, Cui FC, Liu JY. Quantum mechanical/molecular mechanical molecular dynamics and free energy simulations of the thiopurine S-methyltransferase reaction with 6-mercaptopurine. J Phys Chem B 2011; 115:8033-7. [PMID: 21615136 DOI: 10.1021/jp2027516] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Quantum mechanical/molecular mechanical (QM/MM) molecular dynamics simulations were performed to investigate the methylation of 6-mercaptopurine catalyzed by thiopurine S-methyltransferase. Several setups with different tautomeric forms and orientations of the substrate were considered. It is found that, with the orientation in chain A of the X-ray structure, the substrate can form an ideal near-attack configuration for the methylation reaction, which may take place after the deprotonation of the substrate by the conserved residue Asp23 through a water chain. The potential of mean force (PMF) of the methyl-transfer step for the most favorable pathway is 19.6 kcal/mol, which is in good agreement with the available experimental rate constant data.
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Affiliation(s)
- Xiao-Liang Pan
- State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, China
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22
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Characterization of a novel sequence variant, TPMT*28, in the human thiopurine methyltransferase gene. Pharmacogenet Genomics 2011; 20:700-7. [PMID: 20881512 DOI: 10.1097/fpc.0b013e3283402ee4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND The activity of the human enzyme thiopurine methyltransferase (TPMT) varies greatly between individuals because of genetic polymorphism. TPMT is involved in the detoxification and activation of thiopurines such as 6-mercaptopurine, 6-thioguanine, and azathioprine. These drugs are used in the treatment of acute lymphoblastic leukemia and inflammatory bowel disease. A total of 29 sequence variants have been identified so far in the TPMT gene. However, most of these variants are rare and not fully characterized. METHODS AND RESULTS In this study, we describe the identification and characterization of a novel TPMT sequence variant, originally found in a Swedish man of Italian origin. Sequencing of the variable number tandem repeats region of the TPMT promoter and exons III-X revealed a T-to-C transition at nucleotide 611, causing an amino acid substitution from isoleucine to threonine at amino acid 204, positioned in an α-helix, approximately 16 Å from the active site. This new variant was found in the patient and in his son. Both had intermediate enzyme activity (8.1 U/ml packed red blood cells and 8.8 U/ml packed red blood cells, respectively) and neither carried other variants in the coding region of the gene. To be able to study this variant in more detail, the TPMT*28 variant was expressed in Escherichia coli, and an in-vitro characterization of the variant revealed that the protein was destabilized and showed a stronger tendency towards degradation at 37°C than the wild-type protein. The individuals carrying the TPMT*28 variant had less TPMT protein and lower TPMT activity in both red and white blood cells compared with a wild-type control. CONCLUSIONS We present a detailed in-vivo and in-vitro characterization of a novel TPMT sequence variant (TPMT*28) causing decreased TPMT activity. Individuals carrying TPMT*28 might have an increased risk for developing severe side effects if treated with conventional doses of thiopurines.
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23
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Individualized Therapy: Role of Thiopurine S-Methyltransferase Protein and Genetic Variants. J Med Biochem 2010. [DOI: 10.2478/v10011-010-0023-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Individualized Therapy: Role of Thiopurine S-Methyltransferase Protein and Genetic VariantsThiopurine S-methyltransferase (TPMT: EC 2.1.1.67) is an enzyme that metabolizes immunosuppressive thiopurine medications, used in the treatment of autoimmune diseases, cancer and in transplantation medicine. In some individuals, TPMT enzyme activity is significantly increased or decreased compared to the normal TPMT activity level. Structural and biochemical analyses of the TPMT protein revealed the existence of certain protein variants with altered activity. It has been shown that certain TPMT gene polymorphisms exist, that define different TPMT allozymes. Decreased TPMT enzyme activity can also be a consequence of lower protein synthesis, which depends on the promoter transcription activity. Promoter polymorphisms, such as variable number of tandem repeats (VNTR), can modulate the transcription. Administering thiopurine drugs in patients with certain genetic TPMT variants leads to severe hematologic toxicity. To avoid toxicity, therapy is being modified according to the TPMT genotype (pharmacogenetics). We investigated the polymorphisms in exons and regulatory elements (promoter) of the TPMT gene which affect TPMT enzyme activity in the Serbian population. We used PCR-based methodology and sequencing in the detection of genetic variants on TPMT gene. We showed that genetic variants in exons account for 7.5% of all TPMT variants with decreased enzyme activity. The therapy for patients with these pharmacogenetic markers was modified, which contributed to the efficiency of treatment. Functional assaysin vitroshowed that the TPMT promoter activity and, therefore, the quantity of TPMT protein synthesized, depended on the architecture of VNTRs (i.e. number and type) in the promoter. Promoter of the TPMT gene specifically responds to mercaptopurine treatment of K562 cells in a VNTR-dependent manner. Study of DNA-protein interactions revealed that Sp1 and Sp3 transcription factors interact with VNTRs. Our research pointed out that the VNTR promoter region of the TPMT gene could become a new pharmacogenetic marker, clinically significant for the individualization of thiopurine therapy.
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Feng Q, Vannaprasaht S, Peng Y, Angsuthum S, Avihingsanon Y, Yee VC, Tassaneeyakul W, Weinshilboum RM. Thiopurine S-methyltransferase pharmacogenetics: functional characterization of a novel rapidly degraded variant allozyme. Biochem Pharmacol 2009; 79:1053-61. [PMID: 19945438 DOI: 10.1016/j.bcp.2009.11.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Revised: 11/13/2009] [Accepted: 11/20/2009] [Indexed: 11/25/2022]
Abstract
A novel human thiopurine S-methyltransferase (TPMT) variant allele, (319 T>G, 107Tyr>Asp, *27), was identified in a Thai renal transplantation recipient with reduced erythrocyte TPMT activity. The TPMT*27 variant allozyme showed a striking decrease in both immunoreactive protein level and enzyme activity after transient expression in a mammalian cell line. We set out to explore the mechanism(s) responsible for decreased expression of this novel variant of an important drug-metabolizing enzyme. We observed accelerated degradation of TPMT*27 protein in a rabbit reticulocyte lysate. TPMT*27 degradation was slowed by proteasome inhibition and involved chaperone proteins-similar to observations with regard to the degradation of the common TPMT*3A variant allozyme. TPMT*27 aggresome formation was also observed in transfected mammalian cells after proteasome inhibition. Inhibition of autophagy also decreased TPMT*27 degradation. Finally, structural analysis and molecular dynamics simulation indicated that TPMT*27 was less stable than was the wild type TPMT allozyme. In summary, TPMT*27 serves to illustrate the potential importance of protein degradation - both proteasome and autophagy-mediated degradation - for the pharmacogenetic effects of nonsynonymous SNPs.
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Affiliation(s)
- Qiping Feng
- Division of Clinical Pharmacology, Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic-Mayo Medical School, 200 First Street SW, Rochester, MN 55905, United States
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25
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Mokmak W, Tongsima S, Jenwitheesuk E. Molecular dynamics simulation of a human thiopurine S-methyltransferase complexed with 6-mercaptopurine model. Bioinformation 2009; 4:59-62. [PMID: 20198169 PMCID: PMC2823381 DOI: 10.6026/97320630004059] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2009] [Revised: 04/21/2009] [Accepted: 07/18/2009] [Indexed: 11/23/2022] Open
Abstract
Human thiopurine S-methyltransferase (TPMT) is an essential protein in 6-mercaptopurine (6MP) drug metabolism. To understand the
pharmacogenetics of TPMT and 6MP, X-ray co-crystal structures of TPMT complexes with S-adenosyl-L-methionine (AdoMet) and 6MP
are required. However, the co-crystal structure of this complex has not been reported because 6MP is poorly water soluble. We used
molecular dynamics (MD) simulation to predict the structure of the complex of human TPMT-AdoHcy(CH2)6MP, where the sulfur atoms of
AdoHcy and 6MP were linked by a CH2 group. After 1300 picoseconds of MD simulation, the trajectory showed that 6MP was stabilized in
the TPMT active site by formation of non-bonded interactions between 6MP and Phe40, Pro196 and Arg226 side chains of TPMT. The
intersulfur distance between AdoHcy and 6MP as well as the binding modes and the interactions of our TPMT-AdoHcy model are
consistent with those observed in the X-ray crystal structure of murine TPMT-AdoHcy-6MP complex. The predicted binding modes of
AdoHcy and 6MP in our model are consistent with those observed in murine TPMT X-ray crystal structures, which provides structural
insights into the interactions of TPMT, AdoHcy, and 6MP at the atomic level and may be used as a starting point for further study of
thiopurine drug pharmacogenetics.
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Affiliation(s)
- Wanwimon Mokmak
- National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 113 Thailand Science Park, Phahonyothin Road, Klong 1, Klongluang, Pathumthani 12120, Thailand
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