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Mannervik B, Ismail A, Lindström H, Sjödin B, Ing NH. Glutathione Transferases as Efficient Ketosteroid Isomerases. Front Mol Biosci 2021; 8:765970. [PMID: 34881290 PMCID: PMC8645602 DOI: 10.3389/fmolb.2021.765970] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 11/01/2021] [Indexed: 01/01/2023] Open
Abstract
In addition to their well-established role in detoxication, glutathione transferases (GSTs) have other biological functions. We are focusing on the ketosteroid isomerase activity, which appears to contribute to steroid hormone biosynthesis in mammalian tissues. A highly efficient GST A3-3 is present in some, but not all, mammals. The alpha class enzyme GST A3-3 in humans and the horse shows the highest catalytic efficiency with kcat/Km values of approximately 107 M-1s-1, ranking close to the most active enzymes known. The expression of GST A3-3 in steroidogenic tissues suggests that the enzyme has evolved to support the activity of 3β-hydroxysteroid dehydrogenase, which catalyzes the formation of 5-androsten-3,17-dione and 5-pregnen-3,20-dione that are substrates for the double-bond isomerization catalyzed by GST A3-3. The dehydrogenase also catalyzes the isomerization, but its kcat of approximately 1 s-1 is 200-fold lower than the kcat values of human and equine GST A3-3. Inhibition of GST A3-3 in progesterone-producing human cells suppress the formation of the hormone. Glutathione serves as a coenzyme contributing a thiolate as a base in the isomerase mechanism, which also involves the active-site Tyr9 and Arg15. These conserved residues are necessary but not sufficient for the ketosteroid isomerase activity. A proper assortment of H-site residues is crucial to efficient catalysis by forming the cavity binding the hydrophobic substrate. It remains to elucidate why some mammals, such as rats and mice, lack GSTs with the prominent ketosteroid isomerase activity found in certain other species. Remarkably, the fruit fly Drosophila melanogaster, expresses a GSTE14 with notable steroid isomerase activity, even though Ser14 has evolved as the active-site residue corresponding to Tyr9 in the mammalian alpha class.
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Affiliation(s)
- Bengt Mannervik
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Aram Ismail
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Helena Lindström
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Birgitta Sjödin
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Nancy H. Ing
- Department of Animal Science, Texas A&M AgriLife Research, Texas A&M University, College Station, TX, United States
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Abstract
The mercapturic acid pathway is a major route for the biotransformation of xenobiotic and endobiotic electrophilic compounds and their metabolites. Mercapturic acids (N-acetyl-l-cysteine S-conjugates) are formed by the sequential action of the glutathione transferases, γ-glutamyltransferases, dipeptidases, and cysteine S-conjugate N-acetyltransferase to yield glutathione S-conjugates, l-cysteinylglycine S-conjugates, l-cysteine S-conjugates, and mercapturic acids; these metabolites constitute a "mercapturomic" profile. Aminoacylases catalyze the hydrolysis of mercapturic acids to form cysteine S-conjugates. Several renal transport systems facilitate the urinary elimination of mercapturic acids; urinary mercapturic acids may serve as biomarkers for exposure to chemicals. Although mercapturic acid formation and elimination is a detoxication reaction, l-cysteine S-conjugates may undergo bioactivation by cysteine S-conjugate β-lyase. Moreover, some l-cysteine S-conjugates, particularly l-cysteinyl-leukotrienes, exert significant pathophysiological effects. Finally, some enzymes of the mercapturic acid pathway are described as the so-called "moonlighting proteins," catalytic proteins that exert multiple biochemical or biophysical functions apart from catalysis.
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Affiliation(s)
- Patrick E Hanna
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN, USA
| | - M W Anders
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, USA
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Robertson GJ, Stoychev SH, Sayed Y, Achilonu I, Dirr HW. The effects of mutating Tyr9 and Arg15 on the structure, stability, conformational dynamics and mechanism of GSTA3-3. Biophys Chem 2017; 224:40-48. [DOI: 10.1016/j.bpc.2017.02.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 02/22/2017] [Accepted: 02/28/2017] [Indexed: 10/20/2022]
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Abstract
The prodrug azathioprine is primarily used for maintaining remission in inflammatory bowel disease, but approximately 30% of the patients suffer adverse side effects. The prodrug is activated by glutathione conjugation and release of 6-mercaptopurine, a reaction most efficiently catalyzed by glutathione transferase (GST) A2-2. Among five genotypes of GST A2-2, the variant A2*E has threefold-fourfold higher catalytic efficiency with azathioprine, suggesting that the expression of A2*E could boost 6-mercaptopurine release and adverse side effects in treated patients. Structure-activity studies of the GST A2-2 variants and homologous alpha class GSTs were made to delineate the determinants of high catalytic efficiency compared to other alpha class GSTs. Engineered chimeras identified GST peptide segments of importance, and replacing the corresponding regions in low-activity GSTs by these short segments produced chimeras with higher azathioprine activity. By contrast, H-site mutagenesis led to decreased azathioprine activity when active-site positions 208 and 213 in these favored segments were mutagenized. Alternative substitutions indicated that hydrophobic residues were favored. A pertinent question is whether variant A2*E represents the highest azathioprine activity achievable within the GST structural framework. This issue was addressed by mutagenesis of H-site residues assumed to interact with the substrate based on molecular modeling. The mutants with notably enhanced activities had small or polar residues in the mutated positions. The most active mutant L107G/L108D/F222H displayed a 70-fold enhanced catalytic efficiency with azathioprine. The determination of its structure by X-ray crystallography showed an expanded H-site, suggesting improved accommodation of the transition state for catalysis.
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Affiliation(s)
- Olof Modén
- Department of Chemistry-BMC, Uppsala University, Uppsala, Sweden
| | - Bengt Mannervik
- Department of Chemistry-BMC, Uppsala University, Uppsala, Sweden; Department of Neurochemistry, Stockholm University, Stockholm, Sweden.
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Li Y, Shi X, Zhang Q, Hu J, Chen J, Wang W. Computational evidence for the detoxifying mechanism of epsilon class glutathione transferase toward the insecticide DDT. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:5008-5016. [PMID: 24678828 DOI: 10.1021/es405230j] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A combined quantum mechanics/molecular mechanics (QM/MM) computation of the detoxifying mechanism of an epsilon class glutathione transferases (GSTs) toward organochlorine insecticide DDT, 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane, has been carried out. The exponential average barrier of the proton transfer mechanism is 15.2 kcal/mol, which is 27.6 kcal/mol lower than that of the GS-DDT conjugant mechanism. It suggests that the detoxifying reaction proceeds via a proton transfer mechanism where GSH acts as a cofactor rather than a conjugate. The study reveals that the protein environment has a strong effect on the reaction barrier. The experimentally proposed residues Arg112, Glu116 and Phe120 were found to have a strong influence on the detoxifying reaction. The influence of residues Pro13, Cys15, His53, Ile55, Glu67, Ser68, Phe115, and Leu119 was detected as well. It is worth noticing that Ile55 facilitates the detoxifying reaction most. On the basis of the structure of DDT, structure 2, (BrC6H4)2CHCCl3, is the best candidate among all the tested structures in resisting the detoxification of enzyme agGSTe2.
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Affiliation(s)
- Yanwei Li
- Environment Research Institute, Shandong University , Jinan 250100, P. R. China
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Dourado DFAR, Fernandes PA, Mannervik B, Ramos MJ. Isomerization of Δ5-androstene-3,17-dione into Δ4-androstene-3,17-dione catalyzed by human glutathione transferase A3-3: a computational study identifies a dual role for glutathione. J Phys Chem A 2014; 118:5790-800. [PMID: 24739064 DOI: 10.1021/jp410810q] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Glutathione transferases (GSTs) are important enzymes in the metabolism of electrophilic xenobiotic and endobiotic toxic compounds. In addition, human GST A3-3 also catalyzes the double bond isomerization of Δ5-androstene-3,17-dione (Δ(5)-AD) and Δ(5)-pregnene-3,20-dione (Δ(5)-PD), which are the immediate precursors of testosterone and progesterone. In fact, GST A3-3 is the most efficient human enzyme known to exist in the catalysis of these reactions. In this work, we have used density functional theory (DFT) calculations to propose a refined mechanism for the isomerization of Δ(5)-AD catalyzed by GST A3-3. In this mechanism the glutathione (GSH) thiol and Tyr9 catalyze the proton transfer from the Δ(5)-AD C4 atom to the Δ(5)-AD C6 atom, with a rate limiting activation energy of 15.8 kcal · mol(-1). GSH has a dual function, because it is also responsible for stabilizing the negative charge that is formed in the O3 atom of the enolate intermediate. The catalytic role of Tyr9 depends on significant conformational rearrangements of its side chain. Neither of these contributions to catalysis has been observed before. Residues Phe10, Leu111, Ala 208, and Ala 216 complete the list of the important catalytic residues. The mechanism detailed here is based on the GST A3-3:GSH:Δ(4)-AD crystal structure and is consistent with all available experimental data.
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Affiliation(s)
- Daniel F A R Dourado
- REQUIMTE/Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto , Rua do Campo Alegre, s/n, 4169-007 Porto, Portugal
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Dourado DFAR, Fernandes PA, Ramos MJ, Mannervik B. Mechanism of glutathione transferase P1-1-catalyzed activation of the prodrug canfosfamide (TLK286, TELCYTA). Biochemistry 2013; 52:8069-78. [PMID: 24066958 DOI: 10.1021/bi4005705] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Canfosfamide (TLK286, TELCYTA) is a prodrug that upon activation by glutathione transferase P1-1 (GST P1-1) yields an anticancer alkylating agent and a glutathione derivative. The rationale underlying the use of TLK286 in chemotherapy is that tumor cells overexpressing GST P1-1 will be locally exposed to the released alkylating agent with limited collateral toxicity to the surrounding normal tissues. TLK286 has demonstrated clinical effects in phase II and III clinical trials for the treatment of malignancies, such as ovarian cancer, nonsmall cell lung cancer, and breast cancer, as a single agent and in combination with other chemotherapeutic agents. In spite of these promising results, the detailed mechanism of GST P1-1 activation of the prodrug has not been elucidated. Here, we propose a mechanism for the TLK286 activation by GST P1-1 on the basis of density functional theory (DFT) and on potential of mean force (PMF) calculations. A catalytic water molecule is instrumental to the activation by forming a network of intermolecular interactions between the active-site Tyr7 hydroxyl and the sulfone and COO(-) groups of TLK286. The results obtained are consistent with the available experimental kinetic data and provide an atomistic understanding of the TLK286 activation mechanism.
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Affiliation(s)
- Daniel F A R Dourado
- REQUIMTE/Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto , Rua do Campo Alegre s/n, 4169-007 Porto, Portugal
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Zoi OG, Thireou TN, Rinotas VE, Tsoungas PG, Eliopoulos EE, Douni EK, Labrou NE, Clonis YD. Designer xanthone: an inhibitor scaffold for MDR-involved human glutathione transferase isoenzyme A1-1. ACTA ACUST UNITED AC 2013; 18:1092-102. [PMID: 23749766 DOI: 10.1177/1087057113492335] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Glutathione transferases (GSTs) are cell detoxifiers involved in multiple drug resistance (MDR), hampering the effectiveness of certain anticancer drugs. To our knowledge, this is the first report on well-defined synthetic xanthones as GST inhibitors. Screening 18 xanthones revealed three derivatives bearing a bromomethyl and a methyl group (7) or two bromomethyl groups (8) or an aldehyde group (17), with high inhibition potency (>85%), manifested by low IC(50) values (7: 1.59 ± 0.25 µM, 8: 5.30 ± 0.30 µM, and 17: 8.56 ± 0.14 µM) and a competitive modality of inhibition versus CDNB (Ki(7) = 0.76 ± 0.18 and Ki(17) = 1.69 ± 0.08 µM). Of them, derivative 17 readily inhibited hGSTA1-1 in colon cancer cell lysate (IC(50) = 10.54 ± 2.41 µM). Furthermore, all three derivatives were cytotoxic to Caco-2 intact cells, with 17 being the least cytotoxic (LC(50) = 151.3 ± 16.3 µM). The xanthone scaffold may be regarded as a pharmacophore for hGSTA1-1 and the three derivatives, especially 17, as potent precursors for the synthesis of new inhibitors and conjugate prodrugs for human GSTs.
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Affiliation(s)
- Ourania G Zoi
- 1Laboratory of Enzyme Technology, Department of Biotechnology, Agricultural University of Athens, Athens, Greece
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9
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Abstract
The conventional analysis of enzyme evolution is to regard one single salient feature as a measure of fitness, expressed in a milieu exposing the possible selective advantage at a given time and location. Given that a single protein may serve more than one function, fitness should be assessed in several dimensions. In the present study we have explored individual mutational steps leading to a triple-point-mutated human GST (glutathione transferase) A2-2 displaying enhanced activity with azathioprine. A total of eight alternative substrates were used to monitor the diverse evolutionary trajectories. The epistatic effects of the mutations on catalytic activity were variable in sign and magnitude and depended on the substrate used, showing that epistasis is a multidimensional quality. Evidently, the multidimensional fitness landscape can lead to alternative trajectories resulting in enzymes optimized for features other than the selectable markers relevant at the origin of the evolutionary process. In this manner the evolutionary response is robust and can adapt to changing environmental conditions.
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Bortolatto CF, Chagas PM, Wilhelm EA, Zeni G, Nogueira CW. 2,2′-dithienyl diselenide, an organoselenium compound, elicits antioxidant action and inhibits monoamine oxidase activity in vitro. J Enzyme Inhib Med Chem 2012; 28:677-84. [DOI: 10.3109/14756366.2012.670805] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Cristiani F. Bortolatto
- Laboratório de Síntese, Reatividade e Avaliação Farmacológica e Toxicológica de Organocalcogênios, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria,
Santa Maria, CEP, RS, Brasil
| | - Pietro M. Chagas
- Laboratório de Síntese, Reatividade e Avaliação Farmacológica e Toxicológica de Organocalcogênios, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria,
Santa Maria, CEP, RS, Brasil
| | - Ethel A. Wilhelm
- Laboratório de Síntese, Reatividade e Avaliação Farmacológica e Toxicológica de Organocalcogênios, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria,
Santa Maria, CEP, RS, Brasil
| | - Gilson Zeni
- Laboratório de Síntese, Reatividade e Avaliação Farmacológica e Toxicológica de Organocalcogênios, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria,
Santa Maria, CEP, RS, Brasil
| | - Cristina W. Nogueira
- Laboratório de Síntese, Reatividade e Avaliação Farmacológica e Toxicológica de Organocalcogênios, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria,
Santa Maria, CEP, RS, Brasil
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Balogh LM, Atkins WM. Interactions of glutathione transferases with 4-hydroxynonenal. Drug Metab Rev 2011; 43:165-78. [PMID: 21401344 DOI: 10.3109/03602532.2011.558092] [Citation(s) in RCA: 267] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Electrophilic products of lipid peroxidation are important contributors to the progression of several pathological states. The prototypical α,β-unsaturated aldehyde, 4-hydroxynonenal (HNE), triggers cellular events associated with oxidative stress, which can be curtailed by the glutathione-dependent elimination of HNE. The glutathione transferases (GSTs) are a major determinate of the intracellular concentration of HNE and can influence susceptibility to toxic effects, particularly when HNE and GST levels are altered in disease states. In this article, we provide a brief summary of the cellular effects of HNE, followed by a review of its GST-catalyzed detoxification, with an emphasis on the structural attributes that play an important role in the interactions with alpha-class GSTs. Some of the key determining characteristics that impart high alkenal activity reside in the unique C-terminal interactions of the GSTA4-4 enzyme. Studies encompassing both kinetic and structural analyses of related isoforms will be highlighted, with additional attention to stereochemical aspects that demonstrate the capacity of GSTA4-4 to detoxify both enantiomers of the biologically relevant racemic mixture while generating a select set of diastereomeric products with subsequent implications. A summary of the literature that examines the interplay between GSTs and HNE in model systems relevant to oxidative stress will also be discussed to demonstrate the magnitude of importance of GSTs in the overall detoxification scheme.
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Affiliation(s)
- Larissa M Balogh
- Department of Pharmacokinetics, Dynamics, and Metabolism, Pfizer Global Research and Development, Pfizer Inc., Groton, CT 06340, USA.
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Li X, Zheng QC, Zhang JL, Zhang HX. Theoretical study on the mechanism of rearrangement reaction catalyzed by N5-carboxyaminoimidazole ribonucleotide mutase. COMPUT THEOR CHEM 2011. [DOI: 10.1016/j.comptc.2010.12.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Dourado DFAR, Fernandes PA, Ramos MJ. Glutathione Transferase Classes Alpha, Pi, and Mu: GSH Activation Mechanism. J Phys Chem B 2010; 114:12972-80. [DOI: 10.1021/jp1053875] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Daniel F. A. R. Dourado
- REQUIMTE/Departamento de Química, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto, Portugal
| | - Pedro Alexandrino Fernandes
- REQUIMTE/Departamento de Química, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto, Portugal
| | - Maria João Ramos
- REQUIMTE/Departamento de Química, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto, Portugal
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14
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Theoretical studies on model reaction pathways of prostaglandin H2 isomerization to prostaglandin D2/E2. Theor Chem Acc 2010. [DOI: 10.1007/s00214-010-0814-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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