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Hubert SM, Samollow PB, Lindström H, Mannervik B, Ing NH. Conservation of Glutathione Transferase mRNA and Protein Sequences Similar to Human and Horse Alpha Class GST A3-3 across Dog, Goat, and Opossum Species. Biomolecules 2023; 13:1420. [PMID: 37759820 PMCID: PMC10526480 DOI: 10.3390/biom13091420] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 08/29/2023] [Accepted: 09/13/2023] [Indexed: 09/29/2023] Open
Abstract
The glutathione transferase A3-3 (GST A3-3) homodimeric enzyme is the most efficient enzyme that catalyzes isomerization of the precursors of testosterone, estradiol, and progesterone in the gonads of humans and horses. However, the presence of GST A3-3 orthologs with equally high ketosteroid isomerase activity has not been verified in other mammalian species, even though pig and cattle homologs have been cloned and studied. Identifying GSTA3 genes is a challenge because of multiple GSTA gene duplications (e.g., 12 in the human genome); consequently, the GSTA3 gene is not annotated in most genomes. To improve our understanding of GSTA3 gene products and their functions across diverse mammalian species, we cloned homologs of the horse and human GSTA3 mRNAs from the testes of a dog, goat, and gray short-tailed opossum, the genomes of which all currently lack GSTA3 gene annotations. The resultant novel GSTA3 mRNA and inferred protein sequences had a high level of conservation with human GSTA3 mRNA and protein sequences (≥70% and ≥64% identities, respectively). Sequence conservation was also apparent for the 12 residues of the "H-site" in the 222 amino acid GSTA3 protein that is known to interact with the steroid substrates. Modeling predicted that the dog GSTA3-3 may be a more active ketosteroid isomerase than the corresponding goat or opossum enzymes. However, expression of the GSTA3 gene was higher in liver than in other dog tissue. Our results improve understanding of the active sites of mammalian GST A3-3 enzymes, inhibitors of which might be useful for reducing steroidogenesis for medical purposes, such as fertility control or treatment of steroid-dependent diseases.
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Affiliation(s)
- Shawna M. Hubert
- Department of Animal Science, Texas A&M AgriLife Research, Texas A&M University, College Station, TX 77843-2471, USA; (S.M.H.); (N.H.I.)
- Department of Thoracic Head & Neck Medical Oncology, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030-4000, USA
| | - Paul B. Samollow
- Department of Veterinary Integrative Biosciences, School of Veterinary Medicine and Biosciences, Texas A&M University, College Station, TX 77843-2471, USA;
| | - Helena Lindström
- Department of Biochemistry and Biophysics, Arrhenius Laboratories, Stockholm University, SE-10691 Stockholm, Sweden;
| | - Bengt Mannervik
- Department of Biochemistry and Biophysics, Arrhenius Laboratories, Stockholm University, SE-10691 Stockholm, Sweden;
| | - Nancy H. Ing
- Department of Animal Science, Texas A&M AgriLife Research, Texas A&M University, College Station, TX 77843-2471, USA; (S.M.H.); (N.H.I.)
- Faculty of Biotechnology, Texas A&M University, College Station, TX 77843-2128, USA
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Musdal Y, Ismail A, Sjödin B, Mannervik B. Potent GST Ketosteroid Isomerase Activity Relevant to Ecdysteroidogenesis in the Malaria Vector Anopheles gambiae. Biomolecules 2023; 13:976. [PMID: 37371556 DOI: 10.3390/biom13060976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 06/03/2023] [Accepted: 06/09/2023] [Indexed: 06/29/2023] Open
Abstract
Nobo is a glutathione transferase (GST) crucially contributing to ecdysteroid biosynthesis in insects of the orders Diptera and Lepidoptera. Ecdysone is a vital steroid hormone in insects, which governs larval molting and metamorphosis, and the suppression of its synthesis has potential as a novel approach to insect growth regulation and combatting vectors of disease. In general, GSTs catalyze detoxication, whereas the specific function of Nobo in ecdysteroidogenesis is unknown. We report that Nobo from the malaria-spreading mosquito Anopheles gambiae is a highly efficient ketosteroid isomerase catalyzing double-bond isomerization in the steroids 5-androsten-3,17-dione and 5-pregnen-3,20-dione. These mammalian ketosteroids are unknown in mosquitoes, but the discovered prominent catalytic activity of these compounds suggests that the unknown Nobo substrate in insects has a ketosteroid functionality. Aminoacid residue Asp111 in Nobo is essential for activity with the steroids, but not for conventional GST substrates. Further characterization of Nobo may guide the development of new insecticides to prevent malaria.
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Affiliation(s)
- Yaman Musdal
- Department of Biochemistry and Biophysics, Stockholm University, SE-10691 Stockholm, Sweden
- Department of Pediatric Genetics, Faculty of Medicine, Hacettepe University, 06230 Ankara, Turkey
| | - Aram Ismail
- Department of Biochemistry and Biophysics, Stockholm University, SE-10691 Stockholm, Sweden
| | - Birgitta Sjödin
- Department of Biochemistry and Biophysics, Stockholm University, SE-10691 Stockholm, Sweden
| | - Bengt Mannervik
- Department of Biochemistry and Biophysics, Stockholm University, SE-10691 Stockholm, Sweden
- Department of Chemistry, Scripps Research, La Jolla, CA 92037, USA
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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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Škerlová J, Ismail A, Lindström H, Sjödin B, Mannervik B, Stenmark P. Structural and functional analysis of the inhibition of equine glutathione transferase A3-3 by organotin endocrine disrupting pollutants. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 268:115960. [PMID: 33162212 DOI: 10.1016/j.envpol.2020.115960] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 10/02/2020] [Accepted: 10/28/2020] [Indexed: 06/11/2023]
Abstract
Organotin compounds are highly toxic environmental pollutants with neurotoxic and endocrine-disrupting effects. They are potent inhibitors of glutathione transferases (GSTs), thus impeding their detoxication and antioxidant functions. Several GSTs, including equine GST A3-3 (EcaGST A3-3), exhibit steroid double-bond isomerase activity and are involved in the biosynthesis of testosterone and progesterone. We have performed enzyme kinetics analyses of the inhibition of EcaGST A3-3 by organotin compounds. We have also solved crystal structures of EcaGST A3-3 in complexes with glutathione, and with glutathione together with covalently bound triethyltin. Our structural data indicate that the tin atom forms strong bonds with a covalent character not only with the glutathione, but also with a tyrosyl residue of the enzyme itself, thereby preventing the release of the glutathione-organotin adduct and completely blocking the enzyme function. This work presents a structural basis for the general mechanism of GST inhibition by organotin compounds and contributes to the understanding of their neurotoxic and endocrine disrupting effects.
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Affiliation(s)
- Jana Škerlová
- Department of Biochemistry and Biophysics, Stockholm University, SE-10691, Stockholm, Sweden
| | - Aram Ismail
- Department of Biochemistry and Biophysics, Stockholm University, SE-10691, Stockholm, Sweden
| | - Helena Lindström
- Department of Biochemistry and Biophysics, Stockholm University, SE-10691, Stockholm, Sweden
| | - Birgitta Sjödin
- Department of Biochemistry and Biophysics, Stockholm University, SE-10691, Stockholm, Sweden
| | - Bengt Mannervik
- Department of Biochemistry and Biophysics, Stockholm University, SE-10691, Stockholm, Sweden.
| | - Pål Stenmark
- Department of Biochemistry and Biophysics, Stockholm University, SE-10691, Stockholm, Sweden; Department of Experimental Medical Science, Lund University, SE-22100, Lund, Sweden.
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Someya S, Kim MJ. Cochlear detoxification: Role of alpha class glutathione transferases in protection against oxidative lipid damage, ototoxicity, and cochlear aging. Hear Res 2020; 402:108002. [PMID: 32600853 DOI: 10.1016/j.heares.2020.108002] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 05/20/2020] [Accepted: 05/23/2020] [Indexed: 02/06/2023]
Abstract
Age-related hearing loss (AHL) is the most common form of hearing impairment. AHL is thought to be a multifactorial condition resulting from the interaction of numerous causes including aging, genetics, exposure to noise, and exposure to endogenous and exogenous toxins. Cells possess many detoxification enzymes capable of removing thousands of cytotoxic xenobiotics and endogenous toxins such as 4-hydroxynonenal (4-HNE), one of the most abundant cytotoxic end products of lipid peroxidation. The cellular detoxification system involves three phases of enzymatic detoxification. Of these, the glutathione transferase (GST) detoxification system converts a toxic compound into a less toxic form by conjugating the toxic compound to reduced glutathione by GST enzymes. In this review, we describe the current understanding of the cochlear detoxification system and examine the growing link between GST detoxification, oxidative lipid damage, ototoxicity, and cochlear aging with a particular focus on the alpha-class GSTs (GSTAs). We also describe how exposure to ototoxic drugs, exposure to noise, or aging results in increased 4-HNE levels, how 4-HNE damages various cell components under stress conditions, and how GSTAs detoxify 4-HNE in the auditory system.
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Affiliation(s)
- Shinichi Someya
- Department of Aging and Geriatric Research, University of Florida, Gainesville, FL, 32611, USA.
| | - Mi-Jung Kim
- Department of Aging and Geriatric Research, University of Florida, Gainesville, FL, 32611, USA
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Škerlová J, Lindström H, Gonis E, Sjödin B, Neiers F, Stenmark P, Mannervik B. Structure and steroid isomerase activity of
Drosophila
glutathione transferase E14 essential for ecdysteroid biosynthesis. FEBS Lett 2020; 594:1187-1195. [DOI: 10.1002/1873-3468.13718] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 11/25/2019] [Accepted: 12/11/2019] [Indexed: 11/10/2022]
Affiliation(s)
- Jana Škerlová
- Department of Biochemistry and Biophysics Stockholm University Sweden
| | - Helena Lindström
- Department of Biochemistry and Biophysics Stockholm University Sweden
| | - Elodie Gonis
- CSGA Laboratory of Taste and Olfaction University Bourgogne Franche‐Comté Dijon France
| | - Birgitta Sjödin
- Department of Biochemistry and Biophysics Stockholm University Sweden
| | - Fabrice Neiers
- CSGA Laboratory of Taste and Olfaction University Bourgogne Franche‐Comté Dijon France
| | - Pål Stenmark
- Department of Biochemistry and Biophysics Stockholm University Sweden
- Department of Experimental Medical Science Lund University Sweden
| | - Bengt Mannervik
- Department of Biochemistry and Biophysics Stockholm University Sweden
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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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Differential expression of NPM, GSTA3, and GNMT in mouse liver following long-term in vivo irradiation by means of uranium tailings. Biosci Rep 2018; 38:BSR20180536. [PMID: 30061177 PMCID: PMC6200700 DOI: 10.1042/bsr20180536] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Revised: 07/21/2018] [Accepted: 07/26/2018] [Indexed: 12/19/2022] Open
Abstract
Uranium tailings (UT) are formed as a byproduct of uranium mining and are of potential risk to living organisms. In the present study, we sought to identify potential biomarkers associated with chronic exposure to low dose rate γ radiation originating from UT. We exposed C57BL/6J mice to 30, 100, or 250 μGy/h of gamma radiation originating from UT samples. Nine animals were included in each treatment group. We observed that the liver central vein was significantly enlarged in mice exposed to dose rates of 100 and 250 μGy/h, when compared with nonirradiated controls. Using proteomic techniques, we identified 18 proteins that were differentially expressed (by a factor of at least 2.5-fold) in exposed animals, when compared with controls. We chose glycine N-methyltransferase (GNMT), glutathione S-transferase A3 (GSTA3), and nucleophosmin (NPM) for further investigations. Our data showed that GNMT (at 100 and 250 μGy/h) and NPM (at 250 μGy/h) were up-regulated, and GSTA3 was down-regulated in all of the irradiated groups, indicating that their expression is modulated by chronic gamma radiation exposure. GNMT, GSTA3, and NPM may therefore prove useful as biomarkers of gamma radiation exposure associated with UT. The mechanisms underlying those changes need to be further studied.
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Lindström H, Peer SM, Ing NH, Mannervik B. Characterization of equine GST A3-3 as a steroid isomerase. J Steroid Biochem Mol Biol 2018; 178:117-126. [PMID: 29180167 DOI: 10.1016/j.jsbmb.2017.11.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Revised: 11/22/2017] [Accepted: 11/23/2017] [Indexed: 01/12/2023]
Abstract
Glutathione transferases (GSTs) comprise a superfamily of enzymes prominently involved in detoxication by making toxic electrophiles more polar and therefore more easily excretable. However some GSTs have developed alternative functions. Thus, a member of the Alpha class GSTs in pig and human tissues is involved in steroid hormone biosynthesis, catalyzing the obligatory double-bond isomerization of Δ5-androstene-3,17-dione to Δ4-androstene-3,17-dione and of Δ5-pregnene-3,20-dione to Δ4-pregnene-3,20-dione on the biosynthetic pathways to testosterone and progesterone. The human GST A3-3 is the most efficient steroid double-bond isomerase known so far in mammals. The current work extends discoveries of GST enzymes that act in the steroidogenic pathways in large mammals. The mRNA encoding the steroid isomerase GST A3-3 was cloned from testis of the horse (Equus ferus caballus). The concentrations of GSTA3 mRNA were highest in hormone-producing organs such as ovary, testis and adrenal gland. EcaGST A3-3 produced in E. coli has been characterized and shown to have highly efficient steroid double-bond isomerase activity, exceeding its activities with conventional GST substrates. The enzyme now ranks as one of the most efficient steroid isomerases known in mammals and approaches the activity of the bacterial ketosteroid isomerase, one of the most efficient enzymes of all categories known today. The high efficiency and the tissue distribution of EcaGST A3-3 support the view that the enzyme plays a physiologically significant role in the biosynthesis of steroid hormones.
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Affiliation(s)
- Helena Lindström
- Department of Neurochemistry, Stockholm University, Arrhenius Laboratories, SE-10691 Stockholm, Sweden
| | - Shawna M Peer
- Department of Animal Science, Texas A&M University, 2471 TAMU, College Station, TX 77843-2471, USA
| | - Nancy H Ing
- Department of Animal Science, Texas A&M University, 2471 TAMU, College Station, TX 77843-2471, USA.
| | - Bengt Mannervik
- Department of Neurochemistry, Stockholm University, Arrhenius Laboratories, SE-10691 Stockholm, Sweden.
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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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Di-Luoffo M, Brousseau C, Bergeron F, Tremblay JJ. The Transcription Factor MEF2 Is a Novel Regulator of Gsta Gene Class in Mouse MA-10 Leydig Cells. Endocrinology 2015; 156:4695-706. [PMID: 26393304 DOI: 10.1210/en.2015-1500] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Testosterone is essential for spermatogenesis and the development of male sexual characteristics. However, steroidogenesis produces a significant amount of reactive oxygen species (ROS), which can disrupt testosterone production. The myocyte enhancer factor 2 (MEF2) is an important regulator of organogenesis and cell differentiation in various tissues. In the testis, MEF2 is present in Sertoli and Leydig cells throughout fetal and adult life. MEF2-deficient MA-10 Leydig cells exhibit a significant decrease in steroidogenesis concomitant with a reduction in glutathione S-transferase (GST) activity and in the expression of the 4 Gsta members (GST) that encode ROS inactivating enzymes. Here, we report a novel role for MEF2 in ROS detoxification by directly regulating Gsta expression in Leydig cells. Endogenous Gsta1-4 mRNA levels were decreased in MEF2-deficient MA-10 Leydig cells. Conversely, overexpression of MEF2 increased endogenous Gsta1 levels. MEF2 recruitment to the proximal Gsta1 promoter and direct binding on the -506-bp MEF2 element were confirmed by chromatin immunoprecipitation and DNA precipitation assays. In MA-10 Leydig cells, MEF2 activates the Gsta1 promoter and cooperates with Ca(2+)/calmodulin-dependent kinases I to further enhance Gsta1 promoter activity. These effects were lost when the -506-bp MEF2 element was mutated or when a MEF2-Engrailed dominant negative protein was used. Similar results were obtained on the Gsta2, Gsta3, and Gsta4 promoters, suggesting a global role for MEF2 factors in the regulation of all 4 Gsta genes. Altogether, our results identify a novel role for MEF2 in the expression of genes involved in ROS detoxification, a process essential for adequate testosterone production in Leydig cells.
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Affiliation(s)
- Mickaël Di-Luoffo
- Reproduction, Mother and Child Health (M.D.-L., C.B., F.B., J.J.T.), Centre de Recherche du Centre Hospitalier Universitaire de Québec, Québec City, Québec, Canada G1V 4G2; and Centre de Recherche en Biologie de la Reproduction (J.J.T.), Department of Obstetrics, Gynecology, and Reproduction, Faculty of Medicine, Université Laval, Québec City, Québec, Canada G1V 0A6
| | - Catherine Brousseau
- Reproduction, Mother and Child Health (M.D.-L., C.B., F.B., J.J.T.), Centre de Recherche du Centre Hospitalier Universitaire de Québec, Québec City, Québec, Canada G1V 4G2; and Centre de Recherche en Biologie de la Reproduction (J.J.T.), Department of Obstetrics, Gynecology, and Reproduction, Faculty of Medicine, Université Laval, Québec City, Québec, Canada G1V 0A6
| | - Francis Bergeron
- Reproduction, Mother and Child Health (M.D.-L., C.B., F.B., J.J.T.), Centre de Recherche du Centre Hospitalier Universitaire de Québec, Québec City, Québec, Canada G1V 4G2; and Centre de Recherche en Biologie de la Reproduction (J.J.T.), Department of Obstetrics, Gynecology, and Reproduction, Faculty of Medicine, Université Laval, Québec City, Québec, Canada G1V 0A6
| | - Jacques J Tremblay
- Reproduction, Mother and Child Health (M.D.-L., C.B., F.B., J.J.T.), Centre de Recherche du Centre Hospitalier Universitaire de Québec, Québec City, Québec, Canada G1V 4G2; and Centre de Recherche en Biologie de la Reproduction (J.J.T.), Department of Obstetrics, Gynecology, and Reproduction, Faculty of Medicine, Université Laval, Québec City, Québec, Canada G1V 0A6
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Labrou NE, Papageorgiou AC, Pavli O, Flemetakis E. Plant GSTome: structure and functional role in xenome network and plant stress response. Curr Opin Biotechnol 2015; 32:186-194. [PMID: 25614070 DOI: 10.1016/j.copbio.2014.12.024] [Citation(s) in RCA: 117] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Revised: 12/20/2014] [Accepted: 12/30/2014] [Indexed: 10/24/2022]
Abstract
Glutathione transferases (GSTs) represent a major group of detoxification enzymes. All plants possess multiple cytosolic GSTs, each of which displays distinct catalytic as well as non-catalytic binding properties. The progress made in recent years in the fields of genomics, proteomics and protein crystallography of GSTs, coupled with studies on their molecular evolution, diversity and substrate specificity has provided new insights into the function of these enzymes. In plants, GSTs appear to be implicated in an array of different functions, including detoxification of xenobiotics and endobiotics, primary and secondary metabolism, stress tolerance, and cell signalling. This review focuses on plant GSTome and attempts to give an overview of its catalytic and functional role in xenome and plant stress regulatory networks.
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Affiliation(s)
- Nikolaos E Labrou
- Laboratory of Enzyme Technology, Department of Biotechnology, School of Food, Biotechnology and Development, Agricultural University of Athens, 75 Iera Odos Street, GR-11855 Athens, Greece.
| | | | - Ourania Pavli
- University of Thessaly, School of Agricultural Sciences, Department of Agriculture, Crop Production and Rural Environment, Fytokoy Street, 384 46 N. Ionia, Magnisia, Greece
| | - Emmanouil Flemetakis
- Laboratory of Molecular Biology, Department of Biotechnology, School of Food, Biotechnology and Development, Agricultural University of Athens, Athens, Greece
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13
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Daka JL, Achilonu I, Dirr HW. The isomerization of Δ5-androstene-3,17-dione by the human glutathione transferase A3-3 proceeds via a conjugated heteroannular diene intermediate. J Biol Chem 2014; 289:32243-32252. [PMID: 25248748 PMCID: PMC4231698 DOI: 10.1074/jbc.m114.601609] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 09/22/2014] [Indexed: 11/06/2022] Open
Abstract
The seemingly simple proton abstraction reactions underpin many chemical transformations, including isomerization reactions, and are thus of immense biological significance. Despite the energetic cost, enzyme-catalyzed proton abstraction reactions show remarkable rate enhancements. The pathways leading to these accelerated rates are numerous and on occasion partly enigmatic. The isomerization of the steroid Δ(5)-androstene-3,17-dione by the glutathione transferase A3-3 in mammals was investigated to gain insight into the mechanism. Particular emphasis was placed on the nature of the transition state, the intermediate suspected of aiding this process, and the hydrogen bonds postulated to be the stabilizing forces of these transient species. The UV-visible detection of the intermediate places this species in the catalytic pathway, whereas fluorescence spectroscopy is used to obtain the binding constant of the analog intermediate, equilenin. Solvent isotope exchange reveals that proton abstraction from the substrate to form the intermediate is rate-limiting. Analysis of the data in terms of the Marcus formalism indicates that the human glutathione transferase A3-3 lowers the intrinsic kinetic barrier by 3 kcal/mol. The results lead to the conclusion that this reaction proceeds through an enforced concerted mechanism in which the barrier to product formation is kinetically insignificant.
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Affiliation(s)
- Jonathan L Daka
- Protein Structure-Function Research Unit, School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg 2050, South Africa
| | - Ikechukwu Achilonu
- Protein Structure-Function Research Unit, School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg 2050, South Africa
| | - Heini W Dirr
- Protein Structure-Function Research Unit, School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg 2050, South Africa.
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