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Shi T, Sun X, Yuan Q, Wang J, Shen X. Exploring the role of flavin-dependent monooxygenases in the biosynthesis of aromatic compounds. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2024; 17:46. [PMID: 38520003 PMCID: PMC10958861 DOI: 10.1186/s13068-024-02490-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Accepted: 03/13/2024] [Indexed: 03/25/2024]
Abstract
Hydroxylated aromatic compounds exhibit exceptional biological activities. In the biosynthesis of these compounds, three types of hydroxylases are commonly employed: cytochrome P450 (CYP450), pterin-dependent monooxygenase (PDM), and flavin-dependent monooxygenase (FDM). Among these, FDM is a preferred choice due to its small molecular weight, stable expression in both prokaryotic and eukaryotic fermentation systems, and a relatively high concentration of necessary cofactors. However, the catalytic efficiency of many FDMs falls short of meeting the demands of large-scale production. Additionally, challenges arise from the limited availability of cofactors and compatibility issues among enzyme components. Recently, significant progress has been achieved in improving its catalytic efficiency, but have not yet detailed and informative viewed so far. Therefore, this review emphasizes the advancements in FDMs for the biosynthesis of hydroxylated aromatic compounds and presents a summary of three strategies aimed at enhancing their catalytic efficiency: (a) Developing efficient enzyme mutants through protein engineering; (b) enhancing the supply and rapid circulation of critical cofactors; (c) facilitating cofactors delivery for enhancing FDMs catalytic efficiency. Furthermore, the current challenges and further perspectives on improving catalytic efficiency of FDMs are also discussed.
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Affiliation(s)
- Tong Shi
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, 15 Beisanhuan East Road, Chaoyang District, Beijing, 100029, China
| | - Xinxiao Sun
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, 15 Beisanhuan East Road, Chaoyang District, Beijing, 100029, China
| | - Qipeng Yuan
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, 15 Beisanhuan East Road, Chaoyang District, Beijing, 100029, China
| | - Jia Wang
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, 15 Beisanhuan East Road, Chaoyang District, Beijing, 100029, China.
| | - Xiaolin Shen
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, 15 Beisanhuan East Road, Chaoyang District, Beijing, 100029, China.
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2
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Ganouna-Cohen G, Marcouiller F, Blachot-Minassian B, Demarest M, Beauparlant CJ, Droit A, Belaidi E, Bairam A, Joseph V. Loss of testosterone induces postprandial insulin resistance and increases the expression of the hepatic antioxidant flavin-containing monooxygenases in mice exposed to intermittent hypoxia. Acta Physiol (Oxf) 2024; 240:e14089. [PMID: 38230898 DOI: 10.1111/apha.14089] [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: 06/25/2023] [Revised: 11/29/2023] [Accepted: 01/01/2024] [Indexed: 01/18/2024]
Abstract
AIM We tested the hypothesis that low testosterone alters the effects of intermittent hypoxia (IH) on glucose homeostasis, hepatic oxidative stress, and transcriptomic profile in male mice. METHODS We used sham-operated or orchiectomized (ORX) mice exposed to normoxia (Nx) or IH for 2 weeks. We performed fasting insulin and glucose tolerance tests and assessed fasting and postprandial insulin resistance with the HOMA-IR. The activity of hepatic prooxidant (NADPH oxidase-NOX), antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase-SOD, Cat, GPx), lipid peroxidation (MDA concentration), and the total concentration of glutathione (GSH) were measured under postprandial conditions. mRNA sequencing and pathway enrichment analyses were used to identify hepatic genes underlying the interactions between IH and testosterone. RESULTS In Sham mice, IH improves fasting insulin sensitivity and glucose tolerance, while there are no effects of IH in ORX mice. In ORX mice, IH induces postprandial hyperinsulinemia, insulin resistance, and a prooxidant profile of enzyme activity (low SOD activity) without altering hepatic MDA and GSH content. ORX and IH altered the expression of genes involved in oxidoreductase activities, cytochromes-dependent pathways, and glutathione metabolism. Among the genes upregulated in ORX-IH mice, the flavin-containing monooxygenases (FMO) are particularly relevant since these are potent hepatic antioxidants that could help prevent overt oxidative stress in ORX-IH mice. CONCLUSION Low levels of testosterone in male mice exposed to IH induce post-prandial hyperinsulinemia and insulin resistance and determine the mechanisms by which the liver handles IH-induced oxidative stress.
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Affiliation(s)
- Gauthier Ganouna-Cohen
- Département de Pédiatrie, Faculté de Médecine, Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Quebec, Canada
| | - François Marcouiller
- Département de Pédiatrie, Faculté de Médecine, Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Quebec, Canada
| | - Britanny Blachot-Minassian
- Département de Pédiatrie, Faculté de Médecine, Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Quebec, Canada
- HP2, INSERM, U1300, Université Grenoble Alpes, Grenoble, France
| | - Maud Demarest
- Département de Pédiatrie, Faculté de Médecine, Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Quebec, Canada
| | - Charles Joly Beauparlant
- Département de Médecine Moléculaire, Faculté de Médecine, Centre de Recherche du Centre Hospitalo-Universitaire de Québec, Québec, Quebec, Canada
| | - Arnaud Droit
- Département de Médecine Moléculaire, Faculté de Médecine, Centre de Recherche du Centre Hospitalo-Universitaire de Québec, Québec, Quebec, Canada
| | - Elise Belaidi
- HP2, INSERM, U1300, Université Grenoble Alpes, Grenoble, France
- UMR5305-LBTI, CNRS, Institut de Biologie et Chimie des Protéines, Lyon, France
| | - Aida Bairam
- Département de Pédiatrie, Faculté de Médecine, Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Quebec, Canada
| | - Vincent Joseph
- Département de Pédiatrie, Faculté de Médecine, Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Quebec, Canada
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3
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Cárdenas-Moreno Y, González-Bacerio J, García Arellano H, Del Monte-Martínez A. Oxidoreductase enzymes: Characteristics, applications, and challenges as a biocatalyst. Biotechnol Appl Biochem 2023; 70:2108-2135. [PMID: 37753743 DOI: 10.1002/bab.2513] [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: 09/26/2022] [Accepted: 09/03/2023] [Indexed: 09/28/2023]
Abstract
Oxidoreductases are enzymes with distinctive characteristics that favor their use in different areas, such as agriculture, environmental management, medicine, and analytical chemistry. Among these enzymes, oxidases, dehydrogenases, peroxidases, and oxygenases are very interesting. Because their substrate diversity, they can be used in different biocatalytic processes by homogeneous and heterogeneous catalysis. Immobilization of these enzymes has favored their use in the solution of different biotechnological problems, with a notable increase in the study and optimization of this technology in the last years. In this review, the main structural and catalytical features of oxidoreductases, their substrate specificity, immobilization, and usage in biocatalytic processes, such as bioconversion, bioremediation, and biosensors obtainment, are presented.
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Affiliation(s)
- Yosberto Cárdenas-Moreno
- Laboratory for Enzyme Technology, Centre for Protein Studies, Faculty of Biology, University of Havana, Havana, Cuba
| | - Jorge González-Bacerio
- Laboratory for Enzyme Technology, Centre for Protein Studies, Faculty of Biology, University of Havana, Havana, Cuba
- Department of Biochemistry, Faculty of Biology, University of Havana, Havana, Cuba
| | - Humberto García Arellano
- Department of Environmental Sciences, Division of Health and Biological Sciences, Metropolitan Autonomous University, Lerma, Mexico, Mexico
| | - Alberto Del Monte-Martínez
- Laboratory for Enzyme Technology, Centre for Protein Studies, Faculty of Biology, University of Havana, Havana, Cuba
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4
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Ernst S, Mährlein A, Ritzmann NH, Drees SL, Fetzner S. A comparative study of
N
‐hydroxylating flavoprotein monooxygenases reveals differences in kinetics and cofactor binding. FEBS J 2022; 289:5637-5655. [DOI: 10.1111/febs.16444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 02/21/2022] [Accepted: 03/18/2022] [Indexed: 12/01/2022]
Affiliation(s)
- Simon Ernst
- Institute of Molecular Microbiology and Biotechnology University of Münster Germany
| | - Almuth Mährlein
- Institute of Molecular Microbiology and Biotechnology University of Münster Germany
| | - Niklas H. Ritzmann
- Institute of Molecular Microbiology and Biotechnology University of Münster Germany
| | - Steffen L. Drees
- Institute of Molecular Microbiology and Biotechnology University of Münster Germany
| | - Susanne Fetzner
- Institute of Molecular Microbiology and Biotechnology University of Münster Germany
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5
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Partipilo M, Yang G, Mascotti ML, Wijma HJ, Slotboom DJ, Fraaije MW. A conserved sequence motif in the E. coli soluble FAD-containing pyridine nucleotide transhydrogenase is important for reaction efficiency. J Biol Chem 2022; 298:102304. [PMID: 35933012 PMCID: PMC9460512 DOI: 10.1016/j.jbc.2022.102304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 07/20/2022] [Accepted: 07/21/2022] [Indexed: 11/06/2022] Open
Abstract
Soluble pyridine nucleotide transhydrogenases (STHs) are flavoenzymes involved in the redox homeostasis of the essential cofactors NAD(H) and NADP(H). They catalyze the reversible transfer of reducing equivalents between the two nicotinamide cofactors. The soluble transhydrogenase from Escherichia coli (SthA) has found wide use in both in vivo and in vitro applications to steer reducing equivalents toward NADPH-requiring reactions. However, mechanistic insight into SthA function is still lacking. In this work, we present a biochemical characterization of SthA, focusing for the first time on the reactivity of the flavoenzyme with molecular oxygen. We report on oxidase activity of SthA that takes place both during transhydrogenation and in the absence of an oxidized nicotinamide cofactor as an electron acceptor. We find that this reaction produces the reactive oxygen species hydrogen peroxide and superoxide anion. Furthermore, we explore the evolutionary significance of the well-conserved CXXXXT motif that distinguishes STHs from the related family of flavoprotein disulfide reductases in which a CXXXXC motif is conserved. Our mutational analysis revealed the cysteine and threonine combination in SthA leads to better coupling efficiency of transhydrogenation and reduced reactive oxygen species release compared to enzyme variants with mutated motifs. These results expand our mechanistic understanding of SthA by highlighting reactivity with molecular oxygen and the importance of the evolutionarily conserved sequence motif.
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Affiliation(s)
- Michele Partipilo
- Membrane Enzymology Group, Groningen Institute of Biomolecular Sciences & Biotechnology, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Guang Yang
- Molecular Enzymology Group, Groningen Institute of Biomolecular Sciences & Biotechnology, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Maria Laura Mascotti
- Molecular Enzymology Group, Groningen Institute of Biomolecular Sciences & Biotechnology, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands; IMIBIO-SL CONICET, Facultad de Química Bioquímica y Farmacia, Universidad Nacional de San Luis, Ejercito de los Andes 950, D5700HHW, San Luis, Argentina
| | - Hein J Wijma
- Molecular Enzymology Group, Groningen Institute of Biomolecular Sciences & Biotechnology, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Dirk Jan Slotboom
- Membrane Enzymology Group, Groningen Institute of Biomolecular Sciences & Biotechnology, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
| | - Marco W Fraaije
- Molecular Enzymology Group, Groningen Institute of Biomolecular Sciences & Biotechnology, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
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Identifying a Novel Endoplasmic Reticulum-Related Prognostic Model for Hepatocellular Carcinomas. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2022; 2022:8248355. [PMID: 35915607 PMCID: PMC9338738 DOI: 10.1155/2022/8248355] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 05/11/2022] [Accepted: 06/20/2022] [Indexed: 12/18/2022]
Abstract
From the standpoint of the ER (endoplasmic reticulum), we were interested in identifying hub genes that impact clinical prognosis for HCC (hepatocellular carcinoma) patients and developing an ER-related prognostic model. Using TCGA-LIHC (The Cancer Genome Atlas-Liver Hepatocellular Carcinoma) and GSE14520 datasets, we conducted a series of analyses, which included differential gene screening, clinical prognostic analysis, Lasso regression, nomogram prediction, tumour clustering, gene functional enrichment, and tumour infiltration of immune cells. Following our screening for ER-related genes (
), we conducted a Lasso regression model to obtain five hub genes, KPNA2, FMO3, SPP1, KIF2C, and LPCAT1, using TCGA-LIHC as a training set. According to risk scores, HCC samples within either the TCGG-LIHC or GSE14520 cohort were categorized into high- and low-risk groups. Compared to the high-risk group of HCC patients, patients in the low-risk group had a better prognosis of OS (overall survival) or RFS (relapse-free survival). For TCGA-LIHC training set, with the factors of risk score, stage, age, and sex, we plotted a nomogram for 1-, 3-, and 5-year survival predictions. Our model demonstrated better clinical validity in both TCGA-LIHC and GSE14520 cohorts. Additionally, events related to biological enzyme activity, biological metabolic processes, or the cell cycle were associated with the prognostic risk of ER. Furthermore, two HCC prognosis-associated tumour clusters were identified by ER hub gene-based consensus clustering. Our findings indicated a link between ER prognostic signature-related high/low risk and tumour infiltration levels of several immune cells, such as “macrophages M2/M0” and “regulatory T cells (Tregs).” Overall, we developed a novel ER-related clinical prognostic model for HCC patients.
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Sun CP, Yi J, Wei F, Lv X, Deng S, Zhang BJ, Zhao WY, Ma XC. UV-light-driven photooxidation of harmaline catalyzed by riboflavin: Product characterization and mechanisms. Fitoterapia 2021; 155:105054. [PMID: 34626737 DOI: 10.1016/j.fitote.2021.105054] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 10/02/2021] [Accepted: 10/03/2021] [Indexed: 10/20/2022]
Abstract
β-Carboline alkaloid harmaline (HA) is a candidate drug molecule that has been proven to have broad and significant biological activity. Herein, the effects of HA on the riboflavin (RF)-sensitized photooxidation under aerobic conditions were studied for the first time. The photooxidation reaction of HA catalyzed by RF is triggered by UV light at 365 nm and shows a time-dependent stepwise reaction process. Seven transformed products, including five undescribed compounds, oxoharmalines A-E (1-4 and 7), and two known compounds, N-(2-(6-Methoxy-2-oxoindolin-3-yl)ethyl)acetamide (5) and harmine (6), were isolated and identified from the reaction system, following as the gradual oxidation mechanisms. The rare polymerization and dehydrogenation processes in radical-mediated photocatalytic reactions were involved in the process. The transformed products 2-7 exhibited significant neuroprotective activity in a model of H2O2-introduced injury in SH-SY5Y cells, which suggested that the products of the interaction between HA and vitamins may be beneficial to health.
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Affiliation(s)
- Cheng-Peng Sun
- Dalian Key Laboratory of Metabolic Target Characterization and Traditional Chinese Medicine Intervention, College (Institute) of Integrative Medicine, College of Pharmacy, Dalian Medical University, Dalian, China
| | - Jing Yi
- Dalian Key Laboratory of Metabolic Target Characterization and Traditional Chinese Medicine Intervention, College (Institute) of Integrative Medicine, College of Pharmacy, Dalian Medical University, Dalian, China
| | - Fan Wei
- Department of Clinical Laboratory, the First Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Xia Lv
- Dalian Key Laboratory of Metabolic Target Characterization and Traditional Chinese Medicine Intervention, College (Institute) of Integrative Medicine, College of Pharmacy, Dalian Medical University, Dalian, China
| | - Sa Deng
- Dalian Key Laboratory of Metabolic Target Characterization and Traditional Chinese Medicine Intervention, College (Institute) of Integrative Medicine, College of Pharmacy, Dalian Medical University, Dalian, China
| | - Bao-Jing Zhang
- Dalian Key Laboratory of Metabolic Target Characterization and Traditional Chinese Medicine Intervention, College (Institute) of Integrative Medicine, College of Pharmacy, Dalian Medical University, Dalian, China
| | - Wen-Yu Zhao
- Dalian Key Laboratory of Metabolic Target Characterization and Traditional Chinese Medicine Intervention, College (Institute) of Integrative Medicine, College of Pharmacy, Dalian Medical University, Dalian, China.
| | - Xiao-Chi Ma
- Dalian Key Laboratory of Metabolic Target Characterization and Traditional Chinese Medicine Intervention, College (Institute) of Integrative Medicine, College of Pharmacy, Dalian Medical University, Dalian, China; Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Xuzhou, China.
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8
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Cheropkina H, Catucci G, Marucco A, Fenoglio I, Gilardi G, Sadeghi SJ. Human flavin-containing monooxygenase 1 and its long-sought hydroperoxyflavin intermediate. Biochem Pharmacol 2021; 193:114763. [PMID: 34509493 DOI: 10.1016/j.bcp.2021.114763] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 09/03/2021] [Accepted: 09/07/2021] [Indexed: 01/22/2023]
Abstract
Out of the five isoforms of human flavin-containing monooxygenase (hFMO), FMO1 and FMO3 are the most relevant to Phase I drug metabolism. They are involved in the oxygenation of xenobiotics including drugs and pesticides using NADPH and FAD as cofactors. Majority of the characterization of these enzymes has involved hFMO3, where intermediates of its catalytic cycle have been described. On the other hand, research efforts have so far failed in capturing the same key intermediate that is responsible for the monooxygenation activity of hFMO1. In this work we demonstrate spectrophotometrically the formation of a highly stable C4a-hydroperoxyflavin intermediate of hFMO1 upon reduction by NADPH and in the presence of O2. The measured half-life of this flavin intermediate revealed it to be stable and not fully re-oxidized even after 30 min at 15 °C in the absence of substrate, the highest stability ever observed for a human FMO. In addition, the uncoupling reactions of hFMO1 show that this enzyme is <1% uncoupled in the presence of substrate, forming small amounts of H2O2 with no observable superoxide as confirmed by EPR spin trapping experiments. This behaviour is different from hFMO3, that is shown to form both H2O2 and superoxide anion radical as a result of ∼50% uncoupling. These data are consistent with the higher stability of the hFMO1 intermediate in comparison to hFMO3. Taken together, these data demonstrate the different behaviours of these two closely related enzymes with consequences for drug metabolism as well as possible toxicity due to reactive oxygen species.
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Affiliation(s)
- Hanna Cheropkina
- Department of Life Sciences and Systems Biology, University of Torino, Italy
| | - Gianluca Catucci
- Department of Life Sciences and Systems Biology, University of Torino, Italy
| | - Arianna Marucco
- Department of Life Sciences and Systems Biology, University of Torino, Italy
| | | | - Gianfranco Gilardi
- Department of Life Sciences and Systems Biology, University of Torino, Italy
| | - Sheila J Sadeghi
- Department of Life Sciences and Systems Biology, University of Torino, Italy.
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9
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Bortolussi S, Catucci G, Gilardi G, Sadeghi SJ. N- and S-oxygenation activity of truncated human flavin-containing monooxygenase 3 and its common polymorphic variants. Arch Biochem Biophys 2020; 697:108663. [PMID: 33152328 DOI: 10.1016/j.abb.2020.108663] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 10/26/2020] [Accepted: 10/30/2020] [Indexed: 02/07/2023]
Abstract
Human flavin-containing monooxygenase 3 (FMO3) is a membrane-bound, phase I drug metabolizing enzyme. It is highly polymorphic with some of its variants demonstrating differences in rates of turnover of its substrates: xenobiotics including drugs as well as dietary compounds. In order to measure its in vitro activity and compare any differences between the wild type enzyme and its polymorphic variants, we undertook a systematic study using different engineered proteins, heterologously expressed in bacteria, purified and catalytically characterized with 3 different substrates. These included the full-length as well as the more soluble C-terminal truncated versions of the common polymorphic variants (E158K, V257M and E308G) of FMO3 in addition to the full-length and truncated wild-type proteins. In vitro activity assays were performed with benzydamine, tamoxifen and sulindac sulfide, whose products were measured by HPLC. Differences in catalytic properties between the wild-type FMO3 and its common polymorphic variants were similar to those observed with the truncated, more soluble versions of the enzymes. Interestingly, the truncated enzymes were better catalysts than the full-length proteins. The data obtained point to the feasibility of using the more soluble forms of this enzyme for in vitro drug assays as well as future biotechnological applications possibly in high throughput systems such as bioelectrochemical platforms and biosensors.
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Affiliation(s)
- Stefania Bortolussi
- Department of Life Sciences and Systems Biology, University of Torino, Italy; School of Health, Sport and Bioscience, University of East London, UK.
| | - Gianluca Catucci
- Department of Life Sciences and Systems Biology, University of Torino, Italy.
| | - Gianfranco Gilardi
- Department of Life Sciences and Systems Biology, University of Torino, Italy.
| | - Sheila J Sadeghi
- Department of Life Sciences and Systems Biology, University of Torino, Italy.
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10
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Catucci G, Aramini D, Sadeghi SJ, Gilardi G. Ligand stabilization and effect on unfolding by polymorphism in human flavin-containing monooxygenase 3. Int J Biol Macromol 2020; 162:1484-1493. [PMID: 32781122 DOI: 10.1016/j.ijbiomac.2020.08.032] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 07/24/2020] [Accepted: 08/04/2020] [Indexed: 12/20/2022]
Abstract
Pharmacogenomics is a powerful tool to prevent adverse reactions caused by different response of individuals to drug administration. Single nucleotide polymorphisms (SNPs) represent up to 90% of genetic variations among individuals. Drug metabolizing enzymes are highly polymorphic therefore the kinetic parameters of their catalytic reactions can be significantly influenced. This work reports on the unfolding process of a phase I drug metabolizing enzyme, human flavin-containing monooxygenase 3 (hFMO3) and its single nucleotide polymorphic variants (SNPs) V257M, E158K and E308G. Differential scanning calorimetry (DSC) indicates that the thermal denaturation of the enzyme is irreversible. The melting temperature (Tm) for the (Wild Type) WT and its polymorphic variants is found to be in a range from 46 °C to 50 °C. Also the activation energies of unfolding (Ea) show no significant differences among all proteins investigated (290-328 KJ/mol), except for the E308G variant that showed a significantly higher Ea of 412 KJ/mol. The presence of the bound NADP+ cofactor is found to stabilize all the variants by shifting the main Tm by 4-5 °C for all the proteins, exception made for E308G where no changes are observed. Isothermal titration calorimetry (ITC) was used to characterize the interaction of the protein with NADP+ in terms of dissociation constant (Kd), enthalpy (ΔH) and entropy (ΔS). Kd values of 1.6 and 0.7 μM, ΔH of -13.9 Kcal/mol and -16.8 Kcal/mol, ΔS of -20.5 cal/mol/deg, and -28.5 cal/mol/deg were found for V257M and E158K respectively. E308G was found to be unable to bind the NADP+ cofactor, a result that is in line with the Tm results. Circular dichroism also confirmed an overall lower stability of E308G, while NADP+ was found to give a strong positive shift of the Tm stabilizing the structure of E158K (46.2 to 50.6 °C). Previous data highlighted significant differences in terms of activity among the SNPs of hFMO3. In this work a minor impact of the SNPs was found on the stability of the enzyme in the ligand free form, except for E308G, whereas the binding of NADP+ reveals major differences among WT and polymorphic variants that are all measurable in terms of heat capacity, enthalpy and secondary structure content. These data provide the first direct evidence of ligand stabilization effects on hFMO3 that can explain the differences observed in catalytic efficiencies and serve as the starting point for the development of inhibitors of this enzyme.
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Affiliation(s)
- G Catucci
- Department of Life Sciences and Systems Biology, University of Torino, Italy
| | - D Aramini
- Department of Life Sciences and Systems Biology, University of Torino, Italy
| | - S J Sadeghi
- Department of Life Sciences and Systems Biology, University of Torino, Italy
| | - G Gilardi
- Department of Life Sciences and Systems Biology, University of Torino, Italy.
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Abstract
Trimethylamine N-Oxide (TMAO) is the product of the monooxygenation reaction catalyzed by a drug-metabolizing enzyme, human flavin-containing monooxygenase 3 (hFMO3), and its animal orthologues. For several years, researchers have looked at TMAO and hFMO3 as two distinct molecules playing specific but separate roles, the former to defend saltwater animals from osmotic or hydrostatic stress and the latter to process xenobiotics in men. The presence of high levels of plasmatic TMAO in elasmobranchs and other animals was demonstrated a long time ago, whereas the actual physiological role of hFMO3 is still unknown because the enzyme has been mainly characterized for its ability to oxidize drugs. Recently TMAO was found to be related to several human health conditions such as atherosclerosis, cardiovascular, and renal diseases. This correlation poses a striking question of how other vertebrates (and invertebrates) can survive in the presence of very high TMAO concentrations (micromolar in humans, millimolar in marine mammals and several hundred millimolar in elasmobranchs). Therefore, it is important to address how TMAO, its precursors, and FMO catalytic activity are interconnected.
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