1
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Hardy FJ, Quesne MG, Gérard EF, Zhao J, Ortmayer M, Taylor CJ, Ali HS, Slater JW, Levy CW, Heyes DJ, Bollinger JM, de Visser SP, Green AP. Probing Ferryl Reactivity in a Nonheme Iron Oxygenase Using an Expanded Genetic Code. ACS Catal 2024; 14:11584-11590. [PMID: 39114090 PMCID: PMC11301626 DOI: 10.1021/acscatal.4c02365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2024] [Revised: 07/03/2024] [Accepted: 07/08/2024] [Indexed: 08/10/2024]
Abstract
The ability to introduce noncanonical amino acids as axial ligands in heme enzymes has provided a powerful experimental tool for studying the structure and reactivity of their FeIV=O ("ferryl") intermediates. Here, we show that a similar approach can be used to perturb the conserved Fe coordination environment of 2-oxoglutarate (2OG) dependent oxygenases, a versatile class of enzymes that employ highly-reactive ferryl intermediates to mediate challenging C-H functionalizations. Replacement of one of the cis-disposed histidine ligands in the oxygenase VioC with a less electron donating N δ-methyl-histidine (MeHis) preserves both catalytic function and reaction selectivity. Significantly, the key ferryl intermediate responsible for C-H activation can be accumulated in both the wildtype and the modified protein. In contrast to heme enzymes, where metal-oxo reactivity is extremely sensitive to the nature of the proximal ligand, the rates of C-H activation and the observed large kinetic isotope effects are only minimally affected by axial ligand replacement in VioC. This study showcases a powerful tool for modulating the coordination sphere of nonheme iron enzymes that will enhance our understanding of the factors governing their divergent activities.
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Affiliation(s)
- Florence J. Hardy
- Department
of Chemistry & Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
| | - Matthew G. Quesne
- Research
Complex at Harwell, Rutherford Appleton
Laboratory, Harwell Oxford, Didcot, Oxon OX11
0FA, U.K.
- School
of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, U.K.
| | - Emilie F. Gérard
- Department
of Chemistry & Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
| | - Jingming Zhao
- Department
of Chemistry & Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
| | - Mary Ortmayer
- Department
of Chemistry & Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
| | - Christopher J. Taylor
- Department
of Chemistry & Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
| | - Hafiz S. Ali
- Department
of Chemistry & Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
| | - Jeffrey W. Slater
- Department
of Chemistry and Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Colin W. Levy
- Department
of Chemistry & Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
| | - Derren J. Heyes
- Department
of Chemistry & Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
| | - J. Martin Bollinger
- Department
of Chemistry and Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Sam P. de Visser
- Department
of Chemical Engineering & Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
| | - Anthony P. Green
- Department
of Chemistry & Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
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2
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Krishnan A, Waheed SO, Varghese A, Cherilakkudy FH, Schofield CJ, Karabencheva-Christova TG. Unusual catalytic strategy by non-heme Fe(ii)/2-oxoglutarate-dependent aspartyl hydroxylase AspH. Chem Sci 2024; 15:3466-3484. [PMID: 38455014 PMCID: PMC10915816 DOI: 10.1039/d3sc05974j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Accepted: 02/02/2024] [Indexed: 03/09/2024] Open
Abstract
Biocatalytic C-H oxidation reactions are of important synthetic utility, provide a sustainable route for selective synthesis of important organic molecules, and are an integral part of fundamental cell processes. The multidomain non-heme Fe(ii)/2-oxoglutarate (2OG) dependent oxygenase AspH catalyzes stereoselective (3R)-hydroxylation of aspartyl- and asparaginyl-residues. Unusually, compared to other 2OG hydroxylases, crystallography has shown that AspH lacks the carboxylate residue of the characteristic two-His-one-Asp/Glu Fe-binding triad. Instead, AspH has a water molecule that coordinates Fe(ii) in the coordination position usually occupied by the Asp/Glu carboxylate. Molecular dynamics (MD) and quantum mechanics/molecular mechanics (QM/MM) studies reveal that the iron coordinating water is stabilized by hydrogen bonding with a second coordination sphere (SCS) carboxylate residue Asp721, an arrangement that helps maintain the six coordinated Fe(ii) distorted octahedral coordination geometry and enable catalysis. AspH catalysis follows a dioxygen activation-hydrogen atom transfer (HAT)-rebound hydroxylation mechanism, unusually exhibiting higher activation energy for rebound hydroxylation than for HAT, indicating that the rebound step may be rate-limiting. The HAT step, along with substrate positioning modulated by the non-covalent interactions with SCS residues (Arg688, Arg686, Lys666, Asp721, and Gln664), are essential in determining stereoselectivity, which likely proceeds with retention of configuration. The tetratricopeptide repeat (TPR) domain of AspH influences substrate binding and manifests dynamic motions during catalysis, an observation of interest with respect to other 2OG oxygenases with TPR domains. The results provide unique insights into how non-heme Fe(ii) oxygenases can effectively catalyze stereoselective hydroxylation using only two enzyme-derived Fe-ligating residues, potentially guiding enzyme engineering for stereoselective biocatalysis, thus advancing the development of non-heme Fe(ii) based biomimetic C-H oxidation catalysts, and supporting the proposal that the 2OG oxygenase superfamily may be larger than once perceived.
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Affiliation(s)
- Anandhu Krishnan
- Department of Chemistry, Michigan Technological University Houghton MI 49931 USA
| | - Sodiq O Waheed
- Department of Chemistry, Michigan Technological University Houghton MI 49931 USA
| | - Ann Varghese
- Department of Chemistry, Michigan Technological University Houghton MI 49931 USA
| | | | - Christopher J Schofield
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford OX1 3TA Oxford UK
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3
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Kanazhevskaya LY, Gorbunov AA, Lukina MV, Smyshliaev DA, Zhdanova PV, Lomzov AA, Koval VV. The Role of Key Amino Acids of the Human Fe(II)/2OG-Dependent Dioxygenase ALKBH3 in Structural Dynamics and Repair Activity toward Methylated DNA. Int J Mol Sci 2024; 25:1145. [PMID: 38256217 PMCID: PMC10816986 DOI: 10.3390/ijms25021145] [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: 11/30/2023] [Revised: 01/13/2024] [Accepted: 01/16/2024] [Indexed: 01/24/2024] Open
Abstract
Non-heme dioxygenases of the AlkB family hold a unique position among enzymes that repair alkyl lesions in nucleic acids. These enzymes activate the Fe(II) ion and molecular oxygen through the coupled decarboxylation of the 2-oxoglutarate co-substrate to subsequently oxidize the substrate. ALKBH3 is a human homolog of E. coli AlkB, which displays a specific activity toward N1-methyladenine and N3-methylcytosine bases in single-stranded DNA. Due to the lack of a DNA-bound structure of ALKBH3, the basis of its substrate specificity and structure-function relationships requires further exploration. Here we have combined biochemical and biophysical approaches with site-directed mutational analysis to elucidate the role of key amino acids in maintaining the secondary structure and catalytic activity of ALKBH3. Using stopped-flow fluorescence spectroscopy we have shown that conformational dynamics play a crucial role in the catalytic repair process catalyzed by ALKBH3. A transient kinetic mechanism, which comprises the steps of the specific substrate binding, eversion, and anchoring within the DNA-binding cleft, has been described quantitatively by rate and equilibrium constants. Through CD spectroscopy, we demonstrated that replacing side chains of Tyr143, Leu177, and His191 with alanine results in significant alterations in the secondary structure content of ALKBH3 and decreases the stability of mutant proteins. The bulky side chain of Tyr143 is critical for binding the methylated base and stabilizing its flipped-out conformation, while its hydroxyl group is likely involved in facilitating the product release. The removal of the Leu177 and His191 side chains substantially affects the secondary structure content and conformational flexibility, leading to the complete inactivation of the protein. The mutants lacking enzymatic activity exhibit a marked decrease in antiparallel β-strands, offset by an increase in the helical component.
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Affiliation(s)
- Lyubov Yu. Kanazhevskaya
- Institute of Chemical Biology and Fundamental Medicine (ICBFM), 8 Lavrentiev Ave., Novosibirsk 630090, Russia
| | - Alexey A. Gorbunov
- Institute of Chemical Biology and Fundamental Medicine (ICBFM), 8 Lavrentiev Ave., Novosibirsk 630090, Russia
- Department of Natural Sciences, Novosibirsk State University, 1 Pirogova St., Novosibirsk 630090, Russia
| | - Maria V. Lukina
- Institute of Chemical Biology and Fundamental Medicine (ICBFM), 8 Lavrentiev Ave., Novosibirsk 630090, Russia
- Department of Natural Sciences, Novosibirsk State University, 1 Pirogova St., Novosibirsk 630090, Russia
| | - Denis A. Smyshliaev
- Institute of Chemical Biology and Fundamental Medicine (ICBFM), 8 Lavrentiev Ave., Novosibirsk 630090, Russia
- Department of Natural Sciences, Novosibirsk State University, 1 Pirogova St., Novosibirsk 630090, Russia
| | - Polina V. Zhdanova
- Institute of Chemical Biology and Fundamental Medicine (ICBFM), 8 Lavrentiev Ave., Novosibirsk 630090, Russia
- Department of Natural Sciences, Novosibirsk State University, 1 Pirogova St., Novosibirsk 630090, Russia
| | - Alexander A. Lomzov
- Institute of Chemical Biology and Fundamental Medicine (ICBFM), 8 Lavrentiev Ave., Novosibirsk 630090, Russia
- Department of Natural Sciences, Novosibirsk State University, 1 Pirogova St., Novosibirsk 630090, Russia
| | - Vladimir V. Koval
- Institute of Chemical Biology and Fundamental Medicine (ICBFM), 8 Lavrentiev Ave., Novosibirsk 630090, Russia
- Department of Natural Sciences, Novosibirsk State University, 1 Pirogova St., Novosibirsk 630090, Russia
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4
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Peng Z, Ma J, Christov CZ, Karabencheva-Christova T, Lehnert N, Li D. Kinetic Studies on the 2-Oxoglutarate/Fe(II)-Dependent Nucleic Acid Modifying Enzymes from the AlkB and TET Families. DNA 2023; 3:65-84. [PMID: 38698914 PMCID: PMC11065319 DOI: 10.3390/dna3020005] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/05/2024]
Abstract
Nucleic acid methylations are important genetic and epigenetic biomarkers. The formation and removal of these markers is related to either methylation or demethylation. In this review, we focus on the demethylation or oxidative modification that is mediated by the 2-oxoglutarate (2-OG)/Fe(II)-dependent AlkB/TET family enzymes. In the catalytic process, most enzymes oxidize 2-OG to succinate, in the meantime oxidizing methyl to hydroxymethyl, leaving formaldehyde and generating demethylated base. The AlkB enzyme from Escherichia coli has nine human homologs (ALKBH1-8 and FTO) and the TET family includes three members, TET1 to 3. Among them, some enzymes have been carefully studied, but for certain enzymes, few studies have been carried out. This review focuses on the kinetic properties of those 2-OG/Fe(II)-dependent enzymes and their alkyl substrates. We also provide some discussions on the future directions of this field.
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Affiliation(s)
- Zhiyuan Peng
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI 02881, USA
| | - Jian Ma
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI 02881, USA
| | - Christo Z. Christov
- Department of Chemistry, Michigan Technological University, Houghton, MI 49931, USA
| | | | - Nicolai Lehnert
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Deyu Li
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI 02881, USA
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5
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ALKBH family members as novel biomarkers and prognostic factors in human breast cancer. Aging (Albany NY) 2022; 14:6579-6593. [PMID: 35980268 PMCID: PMC9467415 DOI: 10.18632/aging.204231] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 07/27/2022] [Indexed: 12/11/2022]
Abstract
Breast cancer is the most common lethal carcinoma worldwide and better targeted therapies are still worthy of exploration, having had some great successes already. Abnormal expression of ALKBH members were found in various cancers, and the roles played by it were the focus of attention. The ALKBH gene family encodes nine homologous enzymes (ALKBH1-8 and FTO) to repair DNA or RNA depending on Fe2+ and α-ketoglutarate (α-KG), which is related to carcinogenesis. In this study, we applied several databases to explore the roles of ALKBHs in breast cancer. We found that ALKBH members were abnormal expression in breast cancer and associated with tumor stage and subclasses. Higher alteration rates of ALKBH family were found in breast cancer. Function enrichment revealed that several cancer-associated signal pathways were related to ALKBH family such as PI3K-Akt signaling pathway and axon guidance. Infiltration of immune cells (Eosinophiles, NK CD56bright cells, mast cells, T helper cells and so on) were strongly related to ALKBHs. Moreover, we further found that there was strong correlation between ALKBH7 and higher age, later T stage, ER/PR positive and post-menopause of breast cancer patients, and patients with higher ALKBH7 expression had shorter overall survival (OS) and post progression survival (PPS). In conclusion, our findings may provide novel insights into ALKBH-targeted therapy for breast cancer patients, and ALKBH7 may be a potential prognostic biomarker.
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6
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Waheed SO, Varghese A, Chaturvedi SS, Karabencheva-Christova TG, Christov CZ. How Human TET2 Enzyme Catalyzes the Oxidation of Unnatural Cytosine Modifications in Double-Stranded DNA. ACS Catal 2022; 12:5327-5344. [PMID: 36339349 PMCID: PMC9629818 DOI: 10.1021/acscatal.2c00024] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Methylation of cytosine bases is strongly linked to gene expression, imprinting, aging, and carcinogenesis. The Ten-eleven translocation (TET) family of enzymes, which are Fe(II)/2-oxoglutarate (2OG)-dependent enzymes, employ Fe(IV)=O species to dealkylate the lesioned bases to an unmodified cytosine. Recently, it has been shown that the TET2 enzyme can catalyze promiscuously DNA substrates containing unnatural alkylated cytosine. Such unnatural substrates of TET can be used as direct probes for measuring the TET activity or capturing TET from cellular samples. Herein, we studied the catalytic mechanisms during the oxidation of the unnatural C5-position modifications (5-ethylcytosine (5eC), 5-vinylcytosine (5vC) and 5-ethynylcytosine (5eyC)) and the demethylation of N4-methylated lesions (4-methylcytosine (4mC) and 4,4-dimethylcytosine(4dmC)) of the cytosine base by the TET2 enzyme using molecular dynamics (MD) and combined quantum mechanics and molecular mechanics (QM/MM) computational approaches. The results reveal that the chemical nature of the alkylation of the double-stranded (ds) DNA substrates induces distinct changes in the interactions in the binding site, the second coordination sphere, and long-range correlated motions of the ES complexes. The rate-determining hydrogen atom transfer (HAT) is faster in N4-methyl substituent substrates than in the C5-alkylations. Importantly, the calculations show the preference of hydroxylation over desaturation in both 5eC and 5vC substrates. The studies elucidate the post-hydroxylation rearrangements of the hydroxylated intermediates of 5eyC and 5vC to ketene and 5-formylmethylcytosine (5fmC), respectively, and hydrolysis of hemiaminal intermediate of 4mC to formaldehyde and unmodified cytosine proceed exclusively in aqueous solution outside of the enzyme environment. Overall, the studies show that the chemical nature of the unnatural alkylated cytosine substrates exercises distinct effects on the binding interactions, reaction mechanism, and dynamics of TET2.
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Affiliation(s)
- Sodiq O. Waheed
- Department of Chemistry, Michigan Technological University, Houghton, Michigan 49931, United States
| | - Ann Varghese
- Department of Chemistry, Michigan Technological University, Houghton, Michigan 49931, United States
| | - Shobhit S. Chaturvedi
- Department of Chemistry, Michigan Technological University, Houghton, Michigan 49931, United States
| | | | - Christo Z. Christov
- Department of Chemistry, Michigan Technological University, Houghton, Michigan 49931, United States
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7
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Prakash M, Itoh Y, Fujiwara Y, Takahashi Y, Takada Y, Mellini P, Elboray EE, Terao M, Yamashita Y, Yamamoto C, Yamaguchi T, Kotoku M, Kitao Y, Singh R, Roy R, Obika S, Oba M, Wang DO, Suzuki T. Identification of Potent and Selective Inhibitors of Fat Mass Obesity-Associated Protein Using a Fragment-Merging Approach. J Med Chem 2021; 64:15810-15824. [PMID: 34727689 DOI: 10.1021/acs.jmedchem.1c01107] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Fat mass obesity-associated protein (FTO) is a DNA/RNA demethylase involved in the epigenetic regulation of various genes and is considered a therapeutic target for obesity, cancer, and neurological disorders. Here, we aimed to design novel FTO-selective inhibitors by merging fragments of previously reported FTO inhibitors. Among the synthesized analogues, compound 11b, which merges key fragments of Hz (3) and MA (4), inhibited FTO selectively over alkylation repair homologue 5 (ALKBH5), another DNA/RNA demethylase. Treatment of acute monocytic leukemia NOMO-1 cells with a prodrug of 11b decreased the viability of acute monocytic leukemia cells, increased the level of the FTO substrate N6-methyladenosine in mRNA, and induced upregulation of MYC and downregulation of RARA, which are FTO target genes. Thus, Hz (3)/MA (4) hybrid analogues represent an entry into a new class of FTO-selective inhibitors.
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Affiliation(s)
- Muthuraj Prakash
- Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 1-5 Shimogamohangi-cho, Sakyo-ku, Kyoto 606-0823, Japan
| | - Yukihiro Itoh
- Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 1-5 Shimogamohangi-cho, Sakyo-ku, Kyoto 606-0823, Japan.,SANKEN, Osaka University, Mihogaoka, Ibaraki-shi, Osaka 567-0047, Japan
| | - Yoshie Fujiwara
- Institute for Integrated Cell-Material Sciences (iCeMS), Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto 606-8501, Japan
| | - Yukari Takahashi
- Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 1-5 Shimogamohangi-cho, Sakyo-ku, Kyoto 606-0823, Japan
| | - Yuri Takada
- SANKEN, Osaka University, Mihogaoka, Ibaraki-shi, Osaka 567-0047, Japan
| | - Paolo Mellini
- Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 1-5 Shimogamohangi-cho, Sakyo-ku, Kyoto 606-0823, Japan
| | - Elghareeb E Elboray
- Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 1-5 Shimogamohangi-cho, Sakyo-ku, Kyoto 606-0823, Japan.,Chemistry Department, Faculty of Science, South Valley University, Qena 83523, Egypt
| | - Mitsuhiro Terao
- SANKEN, Osaka University, Mihogaoka, Ibaraki-shi, Osaka 567-0047, Japan
| | | | - Chika Yamamoto
- Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Takao Yamaguchi
- Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Masayuki Kotoku
- Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 1-5 Shimogamohangi-cho, Sakyo-ku, Kyoto 606-0823, Japan
| | - Yuki Kitao
- Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 1-5 Shimogamohangi-cho, Sakyo-ku, Kyoto 606-0823, Japan
| | - Ritesh Singh
- Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 1-5 Shimogamohangi-cho, Sakyo-ku, Kyoto 606-0823, Japan.,Department of Chemistry, Central University of Rajasthan, NH-8, Bandar Sindri, Ajmer 305817, Rajasthan, India
| | - Rohini Roy
- Institute for Integrated Cell-Material Sciences (iCeMS), Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto 606-8501, Japan.,Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Satoshi Obika
- Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Makoto Oba
- Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 1-5 Shimogamohangi-cho, Sakyo-ku, Kyoto 606-0823, Japan
| | - Dan Ohtan Wang
- Institute for Integrated Cell-Material Sciences (iCeMS), Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto 606-8501, Japan.,Center for Biosystems Dynamics Research, RIKEN, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan.,Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Takayoshi Suzuki
- Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 1-5 Shimogamohangi-cho, Sakyo-ku, Kyoto 606-0823, Japan.,SANKEN, Osaka University, Mihogaoka, Ibaraki-shi, Osaka 567-0047, Japan.,CREST, Japan Science and Technology Agency (JST), 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan
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8
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Ramanan R, Waheed SO, Schofield CJ, Christov CZ. What Is the Catalytic Mechanism of Enzymatic Histone N-Methyl Arginine Demethylation and Can It Be Influenced by an External Electric Field? Chemistry 2021; 27:11827-11836. [PMID: 33989435 PMCID: PMC9212892 DOI: 10.1002/chem.202101174] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Indexed: 11/11/2022]
Abstract
Arginine methylation is an important mechanism of epigenetic regulation. Some Fe(II) and 2-oxoglutarate dependent Jumonji-C (JmjC) Nϵ-methyl lysine histone demethylases also have N-methyl arginine demethylase activity. We report combined molecular dynamic (MD) and Quantum Mechanical/Molecular Mechanical (QM/MM) studies on the mechanism of N-methyl arginine demethylation by human KDM4E and compare the results with those reported for N-methyl lysine demethylation by KDM4A. At the KDM4E active site, Glu191, Asn291, and Ser197 form a conserved scaffold that restricts substrate dynamics; substrate binding is also mediated by an out of active site hydrogen-bond between the substrate Ser1 and Tyr178. The calculations imply that in either C-H or N-H potential bond cleaving pathways for hydrogen atom transfer (HAT) during N-methyl arginine demethylation, electron transfer occurs via a σ-channel; the transition state for the N-H pathway is ∼10 kcal/mol higher than for the C-H pathway due to the higher bond dissociation energy of the N-H bond. The results of applying external electric fields (EEFs) reveal EEFs with positive field strengths parallel to the Fe=O bond have a significant barrier-lowering effect on the C-H pathway, by contrast, such EEFs inhibit the N-H activation rate. The overall results imply that KDM4 catalyzed N-methyl arginine demethylation and N-methyl lysine demethylation occur via similar C-H abstraction and rebound mechanisms leading to methyl group hydroxylation, though there are differences in the interactions leading to productive binding of intermediates.
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Affiliation(s)
- Rajeev Ramanan
- Department of Chemistry, Michigan Technological University, Houghton, Michigan 49931, United States
- Present address: Department of Chemistry, National Institute of Technology, Rourkela, Odisha 769001, India
| | - Sodiq O. Waheed
- Department of Chemistry, Michigan Technological University, Houghton, Michigan 49931, United States
| | - Christopher J. Schofield
- The Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, The Chemistry Research Laboratory, Mansfield Road, University of Oxford, OX1 5JJ, United Kingdom
| | - Christo Z. Christov
- Department of Chemistry, Michigan Technological University, Houghton, Michigan 49931, United States
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9
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Marcinkowski M, Pilžys T, Garbicz D, Piwowarski J, Mielecki D, Nowaczyk G, Taube M, Gielnik M, Kozak M, Winiewska-Szajewska M, Szołajska E, Dębski J, Maciejewska AM, Przygońska K, Ferenc K, Grzesiuk E, Poznański J. Effect of Posttranslational Modifications on the Structure and Activity of FTO Demethylase. Int J Mol Sci 2021; 22:ijms22094512. [PMID: 33925955 PMCID: PMC8123419 DOI: 10.3390/ijms22094512] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 04/19/2021] [Accepted: 04/22/2021] [Indexed: 12/13/2022] Open
Abstract
The FTO protein is involved in a wide range of physiological processes, including adipogenesis and osteogenesis. This two-domain protein belongs to the AlkB family of 2-oxoglutarate (2-OG)- and Fe(II)-dependent dioxygenases, displaying N6-methyladenosine (N6-meA) demethylase activity. The aim of the study was to characterize the relationships between the structure and activity of FTO. The effect of cofactors (Fe2+/Mn2+ and 2-OG), Ca2+ that do not bind at the catalytic site, and protein concentration on FTO properties expressed in either E. coli (ECFTO) or baculovirus (BESFTO) system were determined using biophysical methods (DSF, MST, SAXS) and biochemical techniques (size-exclusion chromatography, enzymatic assay). We found that BESFTO carries three phosphoserines (S184, S256, S260), while there were no such modifications in ECFTO. The S256D mutation mimicking the S256 phosphorylation moderately decreased FTO catalytic activity. In the presence of Ca2+, a slight stabilization of the FTO structure was observed, accompanied by a decrease in catalytic activity. Size exclusion chromatography and MST data confirmed the ability of FTO from both expression systems to form homodimers. The MST-determined dissociation constant of the FTO homodimer was consistent with their in vivo formation in human cells. Finally, a low-resolution structure of the FTO homodimer was built based on SAXS data.
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Affiliation(s)
- Michał Marcinkowski
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland; (M.M.); (T.P.); (D.G.); (J.P.); (D.M.); (M.W.-S.); (E.S.); (J.D.); (A.M.M.); (K.P.)
| | - Tomaš Pilžys
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland; (M.M.); (T.P.); (D.G.); (J.P.); (D.M.); (M.W.-S.); (E.S.); (J.D.); (A.M.M.); (K.P.)
| | - Damian Garbicz
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland; (M.M.); (T.P.); (D.G.); (J.P.); (D.M.); (M.W.-S.); (E.S.); (J.D.); (A.M.M.); (K.P.)
| | - Jan Piwowarski
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland; (M.M.); (T.P.); (D.G.); (J.P.); (D.M.); (M.W.-S.); (E.S.); (J.D.); (A.M.M.); (K.P.)
| | - Damian Mielecki
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland; (M.M.); (T.P.); (D.G.); (J.P.); (D.M.); (M.W.-S.); (E.S.); (J.D.); (A.M.M.); (K.P.)
| | - Grzegorz Nowaczyk
- NanoBioMedical Centre, Adam Mickiewicz University, Wszechnicy Piastowskiej 3, 61-614 Poznan, Poland;
| | - Michał Taube
- Department of Macromolecular Physics, Faculty of Physics, Adam Mickiewicz University, Uniwersytetu Poznanskiego 2, 61-614 Poznan, Poland; (M.T.); (M.G.); (M.K.)
| | - Maciej Gielnik
- Department of Macromolecular Physics, Faculty of Physics, Adam Mickiewicz University, Uniwersytetu Poznanskiego 2, 61-614 Poznan, Poland; (M.T.); (M.G.); (M.K.)
| | - Maciej Kozak
- Department of Macromolecular Physics, Faculty of Physics, Adam Mickiewicz University, Uniwersytetu Poznanskiego 2, 61-614 Poznan, Poland; (M.T.); (M.G.); (M.K.)
- National Synchrotron Radiation Centre SOLARIS, Jagiellonian University, Czerwone Maki 98, 30-392 Kraków, Poland
| | - Maria Winiewska-Szajewska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland; (M.M.); (T.P.); (D.G.); (J.P.); (D.M.); (M.W.-S.); (E.S.); (J.D.); (A.M.M.); (K.P.)
| | - Ewa Szołajska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland; (M.M.); (T.P.); (D.G.); (J.P.); (D.M.); (M.W.-S.); (E.S.); (J.D.); (A.M.M.); (K.P.)
| | - Janusz Dębski
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland; (M.M.); (T.P.); (D.G.); (J.P.); (D.M.); (M.W.-S.); (E.S.); (J.D.); (A.M.M.); (K.P.)
| | - Agnieszka M. Maciejewska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland; (M.M.); (T.P.); (D.G.); (J.P.); (D.M.); (M.W.-S.); (E.S.); (J.D.); (A.M.M.); (K.P.)
| | - Kaja Przygońska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland; (M.M.); (T.P.); (D.G.); (J.P.); (D.M.); (M.W.-S.); (E.S.); (J.D.); (A.M.M.); (K.P.)
| | - Karolina Ferenc
- Veterinary Research Centre, Department of Large Animal Diseases and Clinic, Institute of Veterinary Medicine, Warsaw University of Life Sciences, Nowoursynowska 100, 02-797 Warsaw, Poland;
| | - Elżbieta Grzesiuk
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland; (M.M.); (T.P.); (D.G.); (J.P.); (D.M.); (M.W.-S.); (E.S.); (J.D.); (A.M.M.); (K.P.)
- Correspondence: (E.G.); (J.P.)
| | - Jarosław Poznański
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland; (M.M.); (T.P.); (D.G.); (J.P.); (D.M.); (M.W.-S.); (E.S.); (J.D.); (A.M.M.); (K.P.)
- Correspondence: (E.G.); (J.P.)
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10
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Waheed SO, Chaturvedi SS, Karabencheva-Christova TG, Christov CZ. Catalytic Mechanism of Human Ten-Eleven Translocation-2 (TET2) Enzyme: Effects of Conformational Changes, Electric Field, and Mutations. ACS Catal 2021. [DOI: 10.1021/acscatal.0c05034] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Sodiq O. Waheed
- Department of Chemistry, Michigan Technological University, Houghton, Michigan 49931, United States
| | - Shobhit S. Chaturvedi
- Department of Chemistry, Michigan Technological University, Houghton, Michigan 49931, United States
| | | | - Christo Z. Christov
- Department of Chemistry, Michigan Technological University, Houghton, Michigan 49931, United States
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11
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Van Deuren V, Plessers S, Robben J. Structural determinants of nucleobase modification recognition in the AlkB family of dioxygenases. DNA Repair (Amst) 2020; 96:102995. [PMID: 33069898 DOI: 10.1016/j.dnarep.2020.102995] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 09/30/2020] [Indexed: 01/29/2023]
Abstract
Iron-dependent dioxygenases of the AlkB protein family found in most organisms throughout the tree of life play a major role in oxidative dealkylation processes. Many of these enzymes have attracted the attention of researchers across different fields and have been subjected to thorough biochemical characterization because of their link to human health and disease. For example, several mammalian AlkB homologues are involved in the direct reversal of alkylation damage in DNA, while others have been shown to play a regulatory role in epigenetic or epitranscriptomic nucleic acid methylation or in post-translational modifications such as acetylation of actin filaments. These studies show that that divergence in amino acid sequence and structure leads to different characteristics and substrate specificities. In this review, we aim to summarize current insights in the structural features involved in the substrate selection of AlkB homologues, with focus on nucleic acid interactions.
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Affiliation(s)
- V Van Deuren
- Department of Chemistry, KU Leuven, Celestijnenlaan 200G, B-3001, Heverlee, Belgium
| | - S Plessers
- Department of Chemistry, KU Leuven, Celestijnenlaan 200G, B-3001, Heverlee, Belgium
| | - J Robben
- Department of Chemistry, KU Leuven, Celestijnenlaan 200G, B-3001, Heverlee, Belgium.
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12
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Lenz SAP, Li D, Wetmore SD. Insights into the Direct Oxidative Repair of Etheno Lesions: MD and QM/MM Study on the Substrate Scope of ALKBH2 and AlkB. DNA Repair (Amst) 2020; 96:102944. [PMID: 33161373 DOI: 10.1016/j.dnarep.2020.102944] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 07/27/2020] [Accepted: 07/30/2020] [Indexed: 01/09/2023]
Abstract
E. coli AlkB and human ALKBH2 belong to the AlkB family enzymes, which contain several α-ketoglutarate (α-KG)/Fe(II)-dependent dioxygenases that repair alkylated DNA. Specifically, the AlkB enzymes catalyze decarboxylation of α-KG to generate a high-valent Fe(IV)-oxo species that oxidizes alkyl groups on DNA adducts. AlkB and ALKBH2 have been reported to differentially repair select etheno adducts, with preferences for 1,N6-ethenoadenine (1,N6-εA) and 3,N4-ethenocytosine (3,N4-εC) over 1,N2-ethenoguanine (1,N2-εG). However, N2,3-ethenoguanine (N2,3-εG), the most common etheno adduct, is not repaired by the AlkB enzymes. Unfortunately, a structural understanding of the differential activity of E. coli AlkB and human ALKBH2 is lacking due to challenges acquiring atomistic details for a range of substrates using experiments. This study uses both molecular dynamics (MD) simulations and ONIOM(QM:MM) calculations to determine how the active site changes upon binding each etheno adduct and characterizes the corresponding catalytic impacts. Our data reveal that the preferred etheno substrates (1,N6-εA and 3,N4-εC) form favorable interactions with catalytic residues that situate the lesion near the Fe(IV)-oxo species and permit efficient oxidation. In contrast, although the damage remains correctly aligned with respect to the Fe(IV)-oxo moiety, repair of 1,N2-εG is mitigated by increased solvation of the active site and a larger distance between Fe(IV)-oxo and the aberrant carbons. Binding of non-substrate N2,3-εG in the active site disrupts key DNA-enzyme interactions, and positions the aberrant carbon atoms even further from the Fe(IV)-oxo species, leading to prohibitively high barriers for oxidative catalysis. Overall, our calculations provide the first structural insight required to rationalize the experimentally-reported substrate specificities of AlkB and ALKBH2 and thereby highlight the roles of several active site residues in the repair of etheno adducts that directly correlates with available experimental data. These proposed catalytic strategies can likely be generalized to other α-KG/Fe(II)-dependent dioxygenases that play similar critical biological roles, including epigenetic and post-translational regulation.
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Affiliation(s)
- Stefan A P Lenz
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive West, Lethbridge, Alberta, T1K 3M4, Canada
| | - Deyu Li
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI, 02881, USA
| | - Stacey D Wetmore
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive West, Lethbridge, Alberta, T1K 3M4, Canada.
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13
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Waheed S, Ramanan R, Chaturvedi SS, Lehnert N, Schofield CJ, Christov CZ, Karabencheva-Christova TG. Role of Structural Dynamics in Selectivity and Mechanism of Non-heme Fe(II) and 2-Oxoglutarate-Dependent Oxygenases Involved in DNA Repair. ACS CENTRAL SCIENCE 2020; 6:795-814. [PMID: 32490196 PMCID: PMC7256942 DOI: 10.1021/acscentsci.0c00312] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Indexed: 05/08/2023]
Abstract
AlkB and its human homologue AlkBH2 are Fe(II)- and 2-oxoglutarate (2OG)-dependent oxygenases that repair alkylated DNA bases occurring as a consequence of reactions with mutagenic agents. We used molecular dynamics (MD) and combined quantum mechanics/molecular mechanics (QM/MM) methods to investigate how structural dynamics influences the selectivity and mechanisms of the AlkB- and AlkBH2-catalyzed demethylation of 3-methylcytosine (m3C) in single (ssDNA) and double (dsDNA) stranded DNA. Dynamics studies reveal the importance of the flexibility in both the protein and DNA components in determining the preferences of AlkB for ssDNA and of AlkBH2 for dsDNA. Correlated motions, including of a hydrophobic β-hairpin, are involved in substrate binding in AlkBH2-dsDNA. The calculations reveal that 2OG rearrangement prior to binding of dioxygen to the active site Fe is preferred over a ferryl rearrangement to form a catalytically productive Fe(IV)=O intermediate. Hydrogen atom transfer proceeds via a σ-channel in AlkBH2-dsDNA and AlkB-dsDNA; in AlkB-ssDNA, there is a competition between σ- and π-channels, implying that the nature of the complexed DNA has potential to alter molecular orbital interactions during the substrate oxidation. Our results reveal the importance of the overall protein-DNA complex in determining selectivity and how the nature of the substrate impacts the mechanism.
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Affiliation(s)
- Sodiq
O. Waheed
- Department
of Chemistry, Michigan Technological University, Houghton, Michigan 49931, United States
| | - Rajeev Ramanan
- Department
of Chemistry, Michigan Technological University, Houghton, Michigan 49931, United States
| | - Shobhit S. Chaturvedi
- Department
of Chemistry, Michigan Technological University, Houghton, Michigan 49931, United States
| | - Nicolai Lehnert
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Christopher J. Schofield
- The
Chemistry Research Laboratory, The Department of Chemistry, Mansfield
Road, University of Oxford, Oxford OX1 3TA, United Kingdom
| | - Christo Z. Christov
- Department
of Chemistry, Michigan Technological University, Houghton, Michigan 49931, United States
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14
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Chaturvedi S, Ramanan R, Lehnert N, Schofield CJ, Karabencheva-Christova TG, Christov CZ. Catalysis by the Non-Heme Iron(II) Histone Demethylase PHF8 Involves Iron Center Rearrangement and Conformational Modulation of Substrate Orientation. ACS Catal 2020; 10:1195-1209. [PMID: 31976154 PMCID: PMC6970271 DOI: 10.1021/acscatal.9b04907] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 12/10/2019] [Indexed: 02/07/2023]
Abstract
PHF8 (KDM7B) is a human non-heme 2-oxoglutarate (2OG) JmjC domain oxygenase that catalyzes the demethylation of the di/mono-Nε-methylated K9 residue of histone H3. Altered PHF8 activity is linked to genetic diseases and cancer; thus, it is an interesting target for epigenetic modulation. We describe the use of combined quantum mechanics/molecular mechanics (QM/MM) and molecular dynamics (MD) simulations to explore the mechanism of PHF8, including dioxygen activation, 2OG binding modes, and substrate demethylation steps. A PHF8 crystal structure manifests the 2OG C-1 carboxylate bound to iron in a nonproductive orientation, i.e., trans to His247. A ferryl-oxo intermediate formed by activating dioxygen bound to the vacant site in this complex would be nonproductive, i.e., "off-line" with respect to reaction with Nε-methylated K9. We show rearrangement of the "off-line" ferryl-oxo intermediate to a productive "in-line" geometry via a solvent exchange reaction (called "ferryl-flip") is energetically unfavorable. The calculations imply that movement of the 2OG C-1 carboxylate prior to dioxygen binding at a five-coordination stage in catalysis proceeds with a low barrier, suggesting that two possible 2OG C-1 carboxylate geometries can coexist at room temperature. We explored alternative mechanisms for hydrogen atom transfer and show that second sphere interactions orient the Nε-methylated lysine in a conformation where hydrogen abstraction from a methyl C-H bond is energetically more favorable than hydrogen abstraction from the N-H bond of the protonated Nε-methyl group. Using multiple HAT reaction path calculations, we demonstrate the crucial role of conformational flexibility in effective hydrogen transfer. Subsequent hydroxylation occurs through a rebound mechanism, which is energetically preferred compared to desaturation, due to second sphere interactions. The overall mechanistic insights reveal the crucial role of iron-center rearrangement, second sphere interactions, and conformational flexibility in PHF8 catalysis and provide knowledge useful for the design of mechanism-based PHF8 inhibitors.
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Affiliation(s)
- Shobhit
S. Chaturvedi
- Department
of Chemistry, Michigan Technological University, Houghton, Michigan 49931, United States
| | - Rajeev Ramanan
- Department
of Chemistry, Michigan Technological University, Houghton, Michigan 49931, United States
| | - Nicolai Lehnert
- Department
of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | | | | | - Christo Z. Christov
- Department
of Chemistry, Michigan Technological University, Houghton, Michigan 49931, United States
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15
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Kanazhevskaya LY, Alekseeva IV, Fedorova OS. A Single-Turnover Kinetic Study of DNA Demethylation Catalyzed by Fe(II)/α-Ketoglutarate-Dependent Dioxygenase AlkB. Molecules 2019; 24:molecules24244576. [PMID: 31847292 PMCID: PMC6943663 DOI: 10.3390/molecules24244576] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 11/26/2019] [Accepted: 12/11/2019] [Indexed: 01/31/2023] Open
Abstract
AlkB is a Fe(II)/α-ketoglutarate-dependent dioxygenase that repairs some alkylated bases of DNA and RNA in Escherichia coli. In the course of catalysis, oxidation of a co-substrate (α-ketoglutarate, αKG) leads to the formation of a highly reactive ‘oxyferryl’ enzyme-bound intermediate, Fe(IV) = O, ensuring hydroxylation of the alkyl nucleobase adducts. Previous studies have revealed that AlkB is a flexible protein and can adopt different conformations during interactions with cofactors and DNA. To assess the conformational dynamics of the enzyme in complex with single- or double-stranded DNA in real-time mode, we employed the stopped-flow fluorescence method. N1-Methyladenine (m1A) introduced into a sequence of 15-mer oligonucleotides was chosen as the specific damage. Single-turnover kinetics were monitored by means of intrinsic fluorescence of the protein’s Trp residues, fluorescent base analogue 2-aminopurine (2aPu), and a dye–quencher pair (FAM/BHQ1). For all the fluorescent labels, the fluorescent traces showed several phases of consistent conformational changes, which were assigned to specific steps of the enzymatic process. These data offer an overall picture of the structural dynamics of AlkB and DNA during their interaction.
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Affiliation(s)
| | | | - Olga S. Fedorova
- Correspondence: (L.Y.K.); (O.S.F.); Tel.: +7-(383)-3635175 (O.S.F.)
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16
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Zeb N, Rashid MH, Mubarak MQE, Ghafoor S, de Visser SP. Flavonol biosynthesis by nonheme iron dioxygenases: A computational study into the structure and mechanism. J Inorg Biochem 2019; 198:110728. [PMID: 31203088 DOI: 10.1016/j.jinorgbio.2019.110728] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 05/13/2019] [Accepted: 05/29/2019] [Indexed: 12/20/2022]
Abstract
Plants produce flavonol compounds for vital functions regarding plant growth, fruit and flower colouring as well as fruit ripening processes. Several of these biosynthesis steps are stereo- and regioselective and are being carried out by nonheme iron enzymes. Using density functional theory calculations on a large active site model complex of flavanone-3β-hydroxylase (FHT), we established the mechanism for conversion of naringenin to its dihydroflavonol, which is a key step in the mechanism of flavonol biosynthesis. The reaction starts with dioxygen binding to the iron(II) centre and a reaction with α-ketoglutarate co-substrate gives succinate, an iron(IV)-oxo species and CO2 with large exothermicity and small reaction barriers. The rate-determining reaction step in the mechanism; however, is hydrogen atom abstraction of an aliphatic CH bond by the iron(IV)-oxo species. We identify a large kinetic isotope effect for the replacement of the transferring hydrogen atom by deuterium. In a final step the OH and substrate radicals combine to form the alcohol product with a barrier of several kcal mol-1. We show that the latter is the result of geometric constraints in the active site pocket. Furthermore, the calculations show that a weak tertiary CH bond is shielded from the iron(IV)-oxo species in the substrate binding position and therefore the enzyme is able to activate a stronger CH bond. As such, the flavanone-3β-hydroxylase enzyme reacts regioselectively with one specific CH bond of naringenin by avoiding activation of weaker bonds through tight substrate and oxidant positioning.
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Affiliation(s)
- Neelam Zeb
- Manchester Institute of Biotechnology and School of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom; National Institute for Biotechnology and Genetic Engineering (NIBGE), Jhang Road, P.O. Box 577, Faisalabad, Pakistan; Pakistan Institute of Engineering and Applied Sciences (PIEAS), Islamabad, Pakistan
| | - Muhammad H Rashid
- National Institute for Biotechnology and Genetic Engineering (NIBGE), Jhang Road, P.O. Box 577, Faisalabad, Pakistan; Pakistan Institute of Engineering and Applied Sciences (PIEAS), Islamabad, Pakistan
| | - M Qadri E Mubarak
- Manchester Institute of Biotechnology and School of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Sidra Ghafoor
- Manchester Institute of Biotechnology and School of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom; Department of Chemistry, Government College University Faisalabad, Jhang Road, 3800 Faisalabad, Pakistan
| | - Sam P de Visser
- Manchester Institute of Biotechnology and School of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom.
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