1
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Pedersen LC, Yi M, Pedersen LG, Kaminski AM. From Steroid and Drug Metabolism to Glycobiology, Using Sulfotransferase Structures to Understand and Tailor Function. Drug Metab Dispos 2022; 50:1027-1041. [PMID: 35197313 PMCID: PMC10753775 DOI: 10.1124/dmd.121.000478] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 12/06/2021] [Indexed: 11/22/2022] Open
Abstract
Sulfotransferases are ubiquitous enzymes that transfer a sulfo group from the universal cofactor donor 3'-phosphoadenosine 5'-phosphosulfate to a broad range of acceptor substrates. In humans, the cytosolic sulfotransferases are involved in the sulfation of endogenous compounds such as steroids, neurotransmitters, hormones, and bile acids as well as xenobiotics including drugs, toxins, and environmental chemicals. The Golgi associated membrane-bound sulfotransferases are involved in post-translational modification of macromolecules from glycosaminoglycans to proteins. The sulfation of small molecules can have profound biologic effects on the functionality of the acceptor, including activation, deactivation, or enhanced metabolism and elimination. Sulfation of macromolecules has been shown to regulate a number of physiologic and pathophysiological pathways by enhancing binding affinity to regulatory proteins or binding partners. Over the last 25 years, crystal structures of these enzymes have provided a wealth of information on the mechanisms of this process and the specificity of these enzymes. This review will focus on the general commonalities of the sulfotransferases, from enzyme structure to catalytic mechanism as well as providing examples into how structural information is being used to either design drugs that inhibit sulfotransferases or to modify the enzymes to improve drug synthesis. SIGNIFICANCE STATEMENT: This manuscript honors Dr. Masahiko Negishi's contribution to the understanding of sulfotransferase mechanism, specificity, and roles in biology by analyzing the crystal structures that have been solved over the last 25 years.
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Affiliation(s)
- Lars C Pedersen
- Genome Integrity and Structural Biology Laboratory (L.C.P., L.G.P., A.M.K.) and Reproductive and Developmental Biology Laboratory (M.Y.), National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina; and Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina (L.G.P.)
| | - MyeongJin Yi
- Genome Integrity and Structural Biology Laboratory (L.C.P., L.G.P., A.M.K.) and Reproductive and Developmental Biology Laboratory (M.Y.), National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina; and Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina (L.G.P.)
| | - Lee G Pedersen
- Genome Integrity and Structural Biology Laboratory (L.C.P., L.G.P., A.M.K.) and Reproductive and Developmental Biology Laboratory (M.Y.), National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina; and Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina (L.G.P.)
| | - Andrea M Kaminski
- Genome Integrity and Structural Biology Laboratory (L.C.P., L.G.P., A.M.K.) and Reproductive and Developmental Biology Laboratory (M.Y.), National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina; and Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina (L.G.P.)
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2
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Dudas B, Toth D, Perahia D, Nicot AB, Balog E, Miteva MA. Insights into the substrate binding mechanism of SULT1A1 through molecular dynamics with excited normal modes simulations. Sci Rep 2021; 11:13129. [PMID: 34162941 PMCID: PMC8222352 DOI: 10.1038/s41598-021-92480-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 06/10/2021] [Indexed: 11/14/2022] Open
Abstract
Sulfotransferases (SULTs) are phase II drug-metabolizing enzymes catalyzing the sulfoconjugation from the co-factor 3′-phosphoadenosine 5′-phosphosulfate (PAPS) to a substrate. It has been previously suggested that a considerable shift of SULT structure caused by PAPS binding could control the capability of SULT to bind large substrates. We employed molecular dynamics (MD) simulations and the recently developed approach of MD with excited normal modes (MDeNM) to elucidate molecular mechanisms guiding the recognition of diverse substrates and inhibitors by SULT1A1. MDeNM allowed exploring an extended conformational space of PAPS-bound SULT1A1, which has not been achieved up to now by using classical MD. The generated ensembles combined with docking of 132 SULT1A1 ligands shed new light on substrate and inhibitor binding mechanisms. Unexpectedly, our simulations and analyses on binding of the substrates estradiol and fulvestrant demonstrated that large conformational changes of the PAPS-bound SULT1A1 could occur independently of the co-factor movements that could be sufficient to accommodate large substrates as fulvestrant. Such structural displacements detected by the MDeNM simulations in the presence of the co-factor suggest that a wider range of drugs could be recognized by PAPS-bound SULT1A1 and highlight the utility of including MDeNM in protein–ligand interactions studies where major rearrangements are expected.
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Affiliation(s)
- Balint Dudas
- Inserm U1268 MCTR, CiTCoM UMR 8038 CNRS - University of Paris, Pharmacy Faculty of Paris, Paris, France.,Laboratoire de Biologie et Pharmacologie Appliquée, Ecole Normale Supérieure Paris-Saclay, UMR 8113, CNRS, Gif-sur-Yvette, France
| | - Daniel Toth
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
| | - David Perahia
- Laboratoire de Biologie et Pharmacologie Appliquée, Ecole Normale Supérieure Paris-Saclay, UMR 8113, CNRS, Gif-sur-Yvette, France
| | - Arnaud B Nicot
- Inserm, Université de Nantes, Centre de Recherche en Transplantation et Immunologie, UMR 1064, ITUN, 44000, Nantes, France
| | - Erika Balog
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary.
| | - Maria A Miteva
- Inserm U1268 MCTR, CiTCoM UMR 8038 CNRS - University of Paris, Pharmacy Faculty of Paris, Paris, France.
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3
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Ji Y, Islam S, Cui H, Dhoke GV, Davari MD, Mertens AM, Schwaneberg U. Loop engineering of aryl sulfotransferase B for improving catalytic performance in regioselective sulfation. Catal Sci Technol 2020. [DOI: 10.1039/d0cy00063a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Loop engineering of aryl sulfotransferase B improves catalytic performance in regioselective sulfation.
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Affiliation(s)
- Yu Ji
- Lehrstuhl für Biotechnologie
- RWTH Aachen University
- 52074 Aachen
- Germany
| | - Shohana Islam
- Lehrstuhl für Biotechnologie
- RWTH Aachen University
- 52074 Aachen
- Germany
- DWI – Leibniz-Institut für Interaktive Materialien e.V
| | - Haiyang Cui
- Lehrstuhl für Biotechnologie
- RWTH Aachen University
- 52074 Aachen
- Germany
| | - Gaurao V. Dhoke
- Lehrstuhl für Biotechnologie
- RWTH Aachen University
- 52074 Aachen
- Germany
| | - Mehdi D. Davari
- Lehrstuhl für Biotechnologie
- RWTH Aachen University
- 52074 Aachen
- Germany
| | - Alan M. Mertens
- Lehrstuhl für Biotechnologie
- RWTH Aachen University
- 52074 Aachen
- Germany
| | - Ulrich Schwaneberg
- Lehrstuhl für Biotechnologie
- RWTH Aachen University
- 52074 Aachen
- Germany
- DWI – Leibniz-Institut für Interaktive Materialien e.V
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4
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Dash R, Ali MC, Dash N, Azad MAK, Hosen SMZ, Hannan MA, Moon IS. Structural and Dynamic Characterizations Highlight the Deleterious Role of SULT1A1 R213H Polymorphism in Substrate Binding. Int J Mol Sci 2019; 20:ijms20246256. [PMID: 31835852 PMCID: PMC6969939 DOI: 10.3390/ijms20246256] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 12/04/2019] [Accepted: 12/09/2019] [Indexed: 12/16/2022] Open
Abstract
Sulfotransferase 1A1 (SULT1A1) is responsible for catalyzing various types of endogenous and exogenous compounds. Accumulating data indicates that the polymorphism rs9282861 (R213H) is responsible for inefficient enzymatic activity and associated with cancer progression. To characterize the detailed functional consequences of this mutation behind the loss-of-function of SULT1A1, the present study deployed molecular dynamics simulation to get insights into changes in the conformation and binding energy. The dynamics scenario of SULT1A1 in both wild and mutated types as well as with and without ligand showed that R213H induced local conformational changes, especially in the substrate-binding loop rather than impairing overall stability of the protein structure. The higher conformational changes were observed in the loop3 (residues, 235-263), turning loop conformation to A-helix and B-bridge, which ultimately disrupted the plasticity of the active site. This alteration reduced the binding site volume and hydrophobicity to decrease the binding affinity of the enzyme to substrates, which was highlighted by the MM-PBSA binding energy analysis. These findings highlight the key insights of structural consequences caused by R213H mutation, which would enrich the understanding regarding the role of SULT1A1 mutation in cancer development and also xenobiotics management to individuals in the different treatment stages.
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Affiliation(s)
- Raju Dash
- Department of Anatomy, Dongguk University College of Medicine, Gyeongju 38066, Korea
| | - Md Chayan Ali
- Department of Biotechnology and Genetic Engineering, Islamic University, Kushtia 7003, Bangladesh
| | - Nayan Dash
- Department of Computer Science and Engineering, BGC Trust University, Bangladesh, Chittagong 4381, Bangladesh
| | - Md Abul Kalam Azad
- Department of Biotechnology and Genetic Engineering, Islamic University, Kushtia 7003, Bangladesh
| | - S M Zahid Hosen
- Pancreatic Research Group, South Western Sydney Clinical School, University of New South Wales, and Ingham Institute for Applied Medical Research, Liverpool, NSW 2170, Australia
| | - Md Abdul Hannan
- Department of Anatomy, Dongguk University College of Medicine, Gyeongju 38066, Korea
- Department of Biochemistry and Molecular Biology, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
| | - Il Soo Moon
- Department of Anatomy, Dongguk University College of Medicine, Gyeongju 38066, Korea
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Brylski O, Ebbinghaus S, Mueller JW. Melting Down Protein Stability: PAPS Synthase 2 in Patients and in a Cellular Environment. Front Mol Biosci 2019; 6:31. [PMID: 31131283 PMCID: PMC6509946 DOI: 10.3389/fmolb.2019.00031] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 04/15/2019] [Indexed: 12/17/2022] Open
Abstract
Within the crowded and complex environment of the cell, a protein experiences stabilizing excluded-volume effects and destabilizing quinary interactions with other proteins. Which of these prevail, needs to be determined on a case-by-case basis. PAPS synthases are dimeric and bifunctional enzymes, providing activated sulfate in the form of 3′-phosphoadenosine-5′-phosphosulfate (PAPS) for sulfation reactions. The human PAPS synthases PAPSS1 and PAPSS2 differ significantly in their protein stability as PAPSS2 is a naturally fragile protein. PAPS synthases bind a series of nucleotide ligands and some of them markedly stabilize these proteins. PAPS synthases are of biomedical relevance as destabilizing point mutations give rise to several pathologies. Genetic defects in PAPSS2 have been linked to bone and cartilage malformations as well as a steroid sulfation defect. All this makes PAPS synthases ideal to study protein unfolding, ligand binding, and the stabilizing and destabilizing factors in their cellular environment. This review provides an overview on current concepts of protein folding and stability and links this with our current understanding of the different disease mechanisms of PAPSS2-related pathologies with perspectives for future research and application.
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Affiliation(s)
- Oliver Brylski
- Institute of Physical and Theoretical Chemistry, Technische Universität Braunschweig, Braunschweig, Germany
| | - Simon Ebbinghaus
- Institute of Physical and Theoretical Chemistry, Technische Universität Braunschweig, Braunschweig, Germany
| | - Jonathan W Mueller
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom.,Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, United Kingdom
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6
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Mueller JW, Idkowiak J, Gesteira TF, Vallet C, Hardman R, van den Boom J, Dhir V, Knauer SK, Rosta E, Arlt W. Human DHEA sulfation requires direct interaction between PAPS synthase 2 and DHEA sulfotransferase SULT2A1. J Biol Chem 2018; 293:9724-9735. [PMID: 29743239 PMCID: PMC6016456 DOI: 10.1074/jbc.ra118.002248] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 04/28/2018] [Indexed: 12/30/2022] Open
Abstract
The high-energy sulfate donor 3′-phosphoadenosine-5′-phosphosulfate (PAPS), generated by human PAPS synthase isoforms PAPSS1 and PAPSS2, is required for all human sulfation pathways. Sulfotransferase SULT2A1 uses PAPS for sulfation of the androgen precursor dehydroepiandrosterone (DHEA), thereby reducing downstream activation of DHEA to active androgens. Human PAPSS2 mutations manifest with undetectable DHEA sulfate, androgen excess, and metabolic disease, suggesting that ubiquitous PAPSS1 cannot compensate for deficient PAPSS2 in supporting DHEA sulfation. In knockdown studies in human adrenocortical NCI-H295R1 cells, we found that PAPSS2, but not PAPSS1, is required for efficient DHEA sulfation. Specific APS kinase activity, the rate-limiting step in PAPS biosynthesis, did not differ between PAPSS1 and PAPSS2. Co-expression of cytoplasmic SULT2A1 with a cytoplasmic PAPSS2 variant supported DHEA sulfation more efficiently than co-expression with nuclear PAPSS2 or nuclear/cytosolic PAPSS1. Proximity ligation assays revealed protein–protein interactions between SULT2A1 and PAPSS2 and, to a lesser extent, PAPSS1. Molecular docking studies showed a putative binding site for SULT2A1 within the PAPSS2 APS kinase domain. Energy-dependent scoring of docking solutions identified the interaction as specific for the PAPSS2 and SULT2A1 isoforms. These findings elucidate the mechanistic basis for the selective requirement for PAPSS2 in human DHEA sulfation.
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Affiliation(s)
- Jonathan W Mueller
- From the Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham B15 2TT, United Kingdom, .,the Centre for Endocrinology, Diabetes and Metabolism (CEDAM), Birmingham Health Partners, Birmingham B15 2TH, United Kingdom
| | - Jan Idkowiak
- From the Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham B15 2TT, United Kingdom.,the Centre for Endocrinology, Diabetes and Metabolism (CEDAM), Birmingham Health Partners, Birmingham B15 2TH, United Kingdom
| | - Tarsis F Gesteira
- the Department of Chemistry, King's College London, London SE1 1DB, United Kingdom, and
| | - Cecilia Vallet
- the Departments of Molecular Biology II, Centre for Medical Biotechnology (ZMB) and
| | - Rebecca Hardman
- From the Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Johannes van den Boom
- Molecular Biology I, Centre for Medical Biotechnology (ZMB), University of Duisburg-Essen, 45141 Essen, Germany
| | - Vivek Dhir
- From the Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Shirley K Knauer
- the Departments of Molecular Biology II, Centre for Medical Biotechnology (ZMB) and
| | - Edina Rosta
- the Department of Chemistry, King's College London, London SE1 1DB, United Kingdom, and
| | - Wiebke Arlt
- From the Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham B15 2TT, United Kingdom.,the Centre for Endocrinology, Diabetes and Metabolism (CEDAM), Birmingham Health Partners, Birmingham B15 2TH, United Kingdom
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7
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Tibbs ZE, Falany CN. An engineered heterodimeric model to investigate SULT1B1 dependence on intersubunit communication. Biochem Pharmacol 2016; 115:123-33. [PMID: 27338799 DOI: 10.1016/j.bcp.2016.06.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 06/17/2016] [Indexed: 01/13/2023]
Abstract
Cytosolic sulfotransferases (SULTs) biotransform small molecules to polar sulfate esters as a means to alter their activities within the body. Understanding the molecular mechanism by which the SULTs perform their function is important for optimizing future therapeutic applications. Recent evidence suggests each SULT isoform acts by a half-site reaction (HSR) mechanism, in which a single SULT dimer subunit is active at any given time. HSR requires communication through the highly conserved KxxxTVxxxE dimerization motif. In this investigation, we sought to test the intersubunit interactions of SULT1B1 as it relates to enzyme activity. We generated two populations of SULT1B1 isoforms that efficiently heterodimerize upon mixing by targeted point mutation of the KxxxTVxxxE motif to KxxxTVxxxK or ExxxTVxxxE. The heterodimer exhibited wildtype-like activity with regard to native size, thermal integrity, PAP affinity, and PAPS Km, therefore serving as a valid model for investigating SULT1B1 dimer subunit interactions. The approach granted control over each independent subunit, permitting mutation of the critical 3'-phosphoadenosine 5'-phosphosulfate (PAPS) binding residue Arg258 and/or the catalytic base His109 in a single subunit of the dimer. Substitution of the dysfunctional subunits for fully active subunits yielded dimeric SULT1B1 with 50% the activity of the fully competent dimer, suggesting SULT1B1 intersubunit communication does not significantly contribute to the isoform's activity. These results are a testament to the unique properties of individual SULT isoforms. The dimerization system described in this manuscript can be used to study subunit interactions in other SULT isoforms as well as proteins in other families.
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Affiliation(s)
- Zachary E Tibbs
- The Department of Pharmacology and Toxicology, The University of Alabama at Birmingham School of Medicine, Birmingham, AL 35294-0019, United States.
| | - Charles N Falany
- The Department of Pharmacology and Toxicology, The University of Alabama at Birmingham School of Medicine, Birmingham, AL 35294-0019, United States.
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8
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Chen BH, Wang CC, Hou YH, Mao YC, Yang YS. Mechanism of sulfotransferase pharmacogenetics in altered xenobiotic metabolism. Expert Opin Drug Metab Toxicol 2015; 11:1053-71. [DOI: 10.1517/17425255.2015.1045486] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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9
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Tibbs ZE, Falany CN. Dimeric human sulfotransferase 1B1 displays cofactor-dependent subunit communication. Pharmacol Res Perspect 2015; 3:e00147. [PMID: 26236487 PMCID: PMC4492763 DOI: 10.1002/prp2.147] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 03/05/2015] [Accepted: 03/22/2015] [Indexed: 01/27/2023] Open
Abstract
The cytosolic sulfotransferases (SULTs) are dimeric enzymes that catalyze the transformation of hydrophobic drugs and hormones into hydrophilic sulfate esters thereby providing the body with an important pathway for regulating small molecule activity and excretion. While SULT dimerization is highly conserved, the necessity for the interaction has not been established. To perform its function, a SULT must efficiently bind the universal sulfate donor, 3'-phosphoadenosine-5'-phosphosulfate (PAPS), and release the byproduct, 3', 5'-diphosphoadenosine (PAP), following catalysis. We hypothesize this efficient binding and release of PAPS/PAP may be connected to SULT dimerization. To allow for the visualization of dynamic protein interactions critical for addressing this hypothesis and to generate kinetically testable hypotheses, molecular dynamic simulations (MDS) of hSULT1B1 were performed with PAPS and PAP bound to each dimer subunit in various combinations. The results suggest the dimer subunits may possess the capability of communicating with one another in a manner dependent on the presence of the cofactor. PAP or PAPS binding to a single side of the dimer results in decreased backbone flexibility of both the bound and unbound subunits, implying the dimer subunits may not act independently. Further, binding of PAP to one subunit of the dimer and PAPS to the other caused increased flexibility in the subunit bound to the inactive cofactor (PAP). These results suggest SULT dimerization may be important in maintaining cofactor binding/release properties of SULTs and provide hypothetical explanations for SULT half-site reactivity and substrate inhibition, which can be analyzed in vitro.
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Affiliation(s)
- Zachary E Tibbs
- The Department of Pharmacology and Toxicology, The University of Alabama at Birmingham Birmingham, Alabama, 35294-0019
| | - Charles N Falany
- The Department of Pharmacology and Toxicology, The University of Alabama at Birmingham Birmingham, Alabama, 35294-0019
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10
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Tibbs ZE, Rohn-Glowacki KJ, Crittenden F, Guidry AL, Falany CN. Structural plasticity in the human cytosolic sulfotransferase dimer and its role in substrate selectivity and catalysis. Drug Metab Pharmacokinet 2015; 30:3-20. [DOI: 10.1016/j.dmpk.2014.10.004] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 10/02/2014] [Accepted: 10/08/2014] [Indexed: 10/24/2022]
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11
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Sidharthan NP, Butcher NJ, Mitchell DJ, Minchin RF. Expression of the orphan cytosolic sulfotransferase SULT4A1 and its major splice variant in human tissues and cells: dimerization, degradation and polyubiquitination. PLoS One 2014; 9:e101520. [PMID: 24988429 PMCID: PMC4079325 DOI: 10.1371/journal.pone.0101520] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 06/08/2014] [Indexed: 11/19/2022] Open
Abstract
The cytosolic sulfotransferase SULT4A1 is highly conserved between mammalian species but its function remains unknown. Polymorphisms in the SULT4A1 gene have been linked to susceptibility to schizophrenia. There are 2 major SULT4A1 transcripts in humans, one that encodes full length protein (wild-type) and one that encodes a truncated protein (variant). Here, we investigated the expression of SULT4A1 in human tissues by RT-PCR and found the wild-type mRNA to be expressed mainly in the brain, gastrointestinal tract and prostate while the splice variant was more widely expressed. In human cell-lines, the wild-type transcript was found in neuronal cells, but the variant transcript was expressed in nearly all other lines examined. Western blot analysis only identified SULT4A1 protein in cells that expressed the wild-type mRNA. No variant protein was detected in cells that expressed the variant mRNA. Ectopically expressed full length SULT4A1 protein was stable while the truncated protein was not, having a half-life of approximately 3 hr. SULT4A1 was also shown to homodimerize, consistent with other SULTs that contain the consensus dimerization motif. Mutation of the dimerization motif resulted in a monomeric form of SULT4A1 that was rapidly degraded by polyubiquitination on the lysine located within the dimerization motif. These results show that SULT4A1 is widely expressed in human tissues, but mostly as a splice variant that produces a rapidly degraded protein. Dimerization protects the protein from degradation. Since many other cytosolic sulfotransferases possess the conserved lysine within the dimerization motif, homodimerization may serve, in part, to stabilize these enzymes in vivo.
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Affiliation(s)
- Neelima P. Sidharthan
- Laboratory for Molecular and Cellular Pharmacology, School of Biomedical Sciences, University of Queensland, Brisbane, Australia
| | - Neville J. Butcher
- Laboratory for Molecular and Cellular Pharmacology, School of Biomedical Sciences, University of Queensland, Brisbane, Australia
| | - Deanne J. Mitchell
- Laboratory for Molecular and Cellular Pharmacology, School of Biomedical Sciences, University of Queensland, Brisbane, Australia
| | - Rodney F. Minchin
- Laboratory for Molecular and Cellular Pharmacology, School of Biomedical Sciences, University of Queensland, Brisbane, Australia
- * E-mail:
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12
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Sun M, Leyh TS. The human estrogen sulfotransferase: a half-site reactive enzyme. Biochemistry 2010; 49:4779-85. [PMID: 20429582 DOI: 10.1021/bi902190r] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The affinity of 17beta-estradiol (E(2)) for the estrogen receptor is weakened beyond the point of physiological relevance by the transfer of the sulfuryl moiety (-SO(3)) from PAPS (3'-phosphoadenosine 5'-phosphosulfate) to the 3'-hydroxyl of E(2). The mechanism of this transfer reaction, catalyzed by estrogen sulfotransferase (EST), is investigated here in detail. The enzyme (a dimer of identical protomers) presents a clear example of half-sites reactivity--only one of the subunits of the dimer produces product during the catalytic cycle. This is the first example of half-sites reactivity in the sulfotransferase family. A burst of product, with an amplitude that corresponds to one-half of the available active sites, reveals that the mechanism is rate-limited by product release. The equilibrium constant governing interconversion of the substrate (E.PAPS.E(2)) and product (E.PAP.E(2)S) central complexes was determined and is strongly biased toward product (K(eq int) approximately 49). Slow product release allows the interconversion of the central complexes to approach equilibrium, with the result that K(eq int) becomes nearly linearly coupled to K(m) and contributes a factor of approximately 30 to the steady-state affinity of the enzyme for substrate. Typical of its family, estrogen sulfotransferase is partially k(cat)-inhibited by its acceptor substrate, E(2). This inhibition does not influence the burst kinetics and thus occurs after formation of the product central complex, a finding consistent with the slow escape of PAP from the nonreactive E.PAP.E(2) complex.
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Affiliation(s)
- Meihao Sun
- Microbiology and Immunology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461-1926, USA
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13
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Hsu CC, Lu LY, Yang YS. From sequence and structure of sulfotransferases and dihydropyrimidinases to an understanding of their mechanisms of action and function. Expert Opin Drug Metab Toxicol 2010; 6:591-601. [DOI: 10.1517/17425251003601987] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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