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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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Zhu J, Qi R, Liu Y, Zhao L, Han W. Mechanistic Insights into the Effect of Ligands on Structural Stability and Selectivity of Sulfotransferase 2A1 (SULT2A1). ACS OMEGA 2019; 4:22021-22034. [PMID: 31891082 PMCID: PMC6933797 DOI: 10.1021/acsomega.9b03136] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 11/14/2019] [Indexed: 05/04/2023]
Abstract
Cytosolic sulfotransferases (SULTs) acting as phase II metabolic enzymes can be used in the sulfonation of small molecules by transferring a sulfonate group from the unique co-factor 3'-phosphoadenosine 5'-phosphosulfate (PAPS) to the substrates. In the present study, molecular dynamics (MD) simulations and ensemble docking study were employed to theoretically characterize the mechanism for the effect of co-factor (PAP) and ligands (LCA, raloxifene, α-hydroxytamoxifen, ouabain, and 3'-phosphoadenylyl sulfate) on structural stability and selectivity of SULT2A1 from the perspective of the dynamic behavior of SULT2A1 structures. Structural stability and network analyses indicated that the cooperation between PAP and LCA may enhance the thermal stability and compact communication in enzymes. During the MD simulations, the obviously rigid region and inward displacement were detected in the active-site cap (loop16) of the conformation containing PAP, which may be responsible for the significant changes in substrate accessibility and catalytic activity. The smaller substrates such as LCA could bind stably to the active pocket in the presence of PAP. However, the substrates or inhibitors with a large spatial structure needed to bind to the open conformation (without PAP) prior to PAPS binding.
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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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4
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Abunnaja MS, Alherz FA, El Daibani AA, Bairam AF, Rasool MI, Gohal SA, Kurogi K, Suiko M, Sakakibara Y, Liu MC. Effects of genetic polymorphisms on the sulfation of dehydroepiandrosterone and pregnenolone by human cytosolic sulfotransferase SULT2A1. Biochem Cell Biol 2018; 96:655-662. [PMID: 29671343 DOI: 10.1139/bcb-2017-0341] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The cytosolic sulfotransferase (SULT) SULT2A1 is known to mediate the sulfation of DHEA as well as some other hydroxysteroids such as pregnenolone. The present study was designed to investigate how genetic polymorphisms of the human SULT2A1 gene may affect the sulfation of DHEA and pregnenolone. Online databases were systematically searched to identify human SULT2A1 single nucleotide polymorphisms (SNPs). Of the 98 SULT2A1 non-synonymous coding SNPs identified, seven were selected for further investigation. Site-directed mutagenesis was used to generate cDNAs encoding these seven SULT2A1 allozymes, which were expressed in BL21 Escherichia coli cells and purified by glutathione-Sepharose affinity chromatography. Enzymatic assays revealed that purified SULT2A1 allozymes displayed differential sulfating activity toward both DHEA and pregnenolone. Kinetic analyses showed further differential catalytic efficiency and substrate affinity of the SULT2A1 allozymes, in comparison with wild-type SULT2A1. These findings provided useful information concerning the effects of genetic polymorphisms on the sulfating activity of SULT2A1 allozymes.
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Affiliation(s)
- Maryam S Abunnaja
- a Department of Pharmacology, College of Pharmacy and Pharmaceutical Sciences, University of Toledo Health Science Campus, Toledo, OH 43614, USA
| | - Fatemah A Alherz
- a Department of Pharmacology, College of Pharmacy and Pharmaceutical Sciences, University of Toledo Health Science Campus, Toledo, OH 43614, USA
| | - Amal A El Daibani
- a Department of Pharmacology, College of Pharmacy and Pharmaceutical Sciences, University of Toledo Health Science Campus, Toledo, OH 43614, USA
| | - Ahsan F Bairam
- a Department of Pharmacology, College of Pharmacy and Pharmaceutical Sciences, University of Toledo Health Science Campus, Toledo, OH 43614, USA.,b Department of Pharmacology, College of Pharmacy, University of Kufa, Najaf, Iraq
| | - Mohammed I Rasool
- a Department of Pharmacology, College of Pharmacy and Pharmaceutical Sciences, University of Toledo Health Science Campus, Toledo, OH 43614, USA.,c Department of Pharmacology, College of Pharmacy, University of Karbala, Karbala, Iraq
| | - Saud A Gohal
- a Department of Pharmacology, College of Pharmacy and Pharmaceutical Sciences, University of Toledo Health Science Campus, Toledo, OH 43614, USA
| | - Katsuhisa Kurogi
- a Department of Pharmacology, College of Pharmacy and Pharmaceutical Sciences, University of Toledo Health Science Campus, Toledo, OH 43614, USA.,d Biochemistry and Applied Biosciences, University of Miyazaki, Miyazaki 889-2192 Japan
| | - Masahito Suiko
- d Biochemistry and Applied Biosciences, University of Miyazaki, Miyazaki 889-2192 Japan
| | - Yoichi Sakakibara
- d Biochemistry and Applied Biosciences, University of Miyazaki, Miyazaki 889-2192 Japan
| | - Ming-Cheh Liu
- a Department of Pharmacology, College of Pharmacy and Pharmaceutical Sciences, University of Toledo Health Science Campus, Toledo, OH 43614, USA
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Cook I, Wang T, Wang W, Kopp F, Wu P, Leyh TS. Controlling Sulfuryl-Transfer Biology. Cell Chem Biol 2017; 23:579-586. [PMID: 27203377 DOI: 10.1016/j.chembiol.2016.04.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 04/06/2016] [Accepted: 04/14/2016] [Indexed: 10/21/2022]
Abstract
In humans, the cytosolic sulfotransferases (SULTs) catalyze regiospecific transfer of the sulfuryl moiety (-SO3) from 3'-phosphoadenosine 5'-phosphosulfate to thousands of metabolites, including numerous signaling small molecules, and thus regulates their activities and half-lives. Imbalances in the in vivo set points of these reactions leads to disease. Here, with the goal of controlling sulfonation in vivo, molecular ligand-recognition principles in the SULT and nuclear receptor families are integrated in creating a strategy that can prevent sulfonation of a compound without significantly altering its receptor affinity, or inhibiting SULTS. The strategy is validated by using it to control the sulfonation and estrogen receptor (ER) activating activity of raloxifene (a US Food and Drug Administration-approved selective estrogen receptor modulator) and its derivatives. Preventing sulfonation is shown to enhance ER-activation efficacy 10(4)-fold in studies using Ishikawa cells. The strategy offers the opportunity to control sulfuryl transfer on a compound-by-compound basis, to enhance the efficacy of sulfonated drugs, and to explore the biology of sulfuryl transfer with unprecedented precision.
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Affiliation(s)
- Ian Cook
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461-1926, USA
| | - Ting Wang
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461-1926, USA
| | - Wei Wang
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461-1926, USA
| | - Felix Kopp
- Department of Chemical Biology Core Facility, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461-1926, USA
| | - Peng Wu
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461-1926, USA
| | - Thomas S Leyh
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461-1926, USA.
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6
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Kurogi K, Yoshihama M, Horton A, Schiefer IT, Krasowski MD, Hagey LR, Williams FE, Sakakibara Y, Kenmochi N, Suiko M, Liu MC. Identification and characterization of 5α-cyprinol-sulfating cytosolic sulfotransferases (Sults) in the zebrafish (Danio rerio). J Steroid Biochem Mol Biol 2017; 174:120-127. [PMID: 28807679 PMCID: PMC5675747 DOI: 10.1016/j.jsbmb.2017.08.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 08/05/2017] [Accepted: 08/07/2017] [Indexed: 12/31/2022]
Abstract
5α-Cyprinol 27-sulfate is the major biliary bile salt present in cypriniform fish including the zebrafish (Danio rerio). The current study was designed to identify the zebrafish cytosolic sulfotransferase (Sult) enzyme(s) capable of sulfating 5α-cyprinol and to characterize the zebrafish 5α-cyprinol-sulfating Sults in comparison with human SULT2A1. Enzymatic assays using zebrafish homogenates showed 5α-cyprinol-sulfating activity. A systematic analysis, using a panel of recombinant zebrafish Sults, revealed two Sult2 subfamily members, Sult2st2 and Sult2st3, as major 5α-cyprinol-sulfating Sults. Both enzymes showed higher activities using 5α-cyprinol as the substrate, compared to their activity with DHEA, a representative substrate for mammalian SULT2 family members, particularly SULT2A1. pH-Dependence and kinetics experiments indicated that the catalytic properties of zebrafish Sult2 family members in mediating the sulfation of 5α-cyprinol were different from those of either zebrafish Sult3st4 or human SULT2A1. Collectively, these results imply that both Sult2st2 and Sult2st3 have evolved to sulfate specifically C27-bile alcohol, 5α-cyprinol, in Cypriniform fish, whereas the enzymatic characteristics of zebrafish Sult3 members, particularly Sult3st4, correlated with those of human SULT2A1.
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Affiliation(s)
- Katsuhisa Kurogi
- Department of Pharmacology, College of Pharmacy, University of Toledo Health Science Campus, Toledo, OH 43614, USA; Biochemistry and Applied Biosciences, University of Miyazaki, Miyazaki 889-2192, Japan
| | - Maki Yoshihama
- Department of Pharmacology, College of Pharmacy, University of Toledo Health Science Campus, Toledo, OH 43614, USA; Frontier Research Center, University of Miyazaki, Miyazaki 889-2192, Japan
| | - Austin Horton
- Department of Pharmacology, College of Pharmacy, University of Toledo Health Science Campus, Toledo, OH 43614, USA
| | - Isaac T Schiefer
- Department of Pharmacology, College of Pharmacy, University of Toledo Health Science Campus, Toledo, OH 43614, USA
| | - Matthew D Krasowski
- Department of Pathology, University of Iowa Hospitals and Clinics, RCP 6233, 200 Hawkins Drive, Iowa City, IA 52242, USA
| | - Lee R Hagey
- Department of Medicine, University of California at San Diego, La Jolla, San Diego, CA 92093, USA
| | - Frederick E Williams
- Department of Pharmacology, College of Pharmacy, University of Toledo Health Science Campus, Toledo, OH 43614, USA
| | - Yoichi Sakakibara
- Biochemistry and Applied Biosciences, University of Miyazaki, Miyazaki 889-2192, Japan
| | - Naoya Kenmochi
- Frontier Research Center, University of Miyazaki, Miyazaki 889-2192, Japan
| | - Masahito Suiko
- Biochemistry and Applied Biosciences, University of Miyazaki, Miyazaki 889-2192, Japan
| | - Ming-Cheh Liu
- Department of Pharmacology, College of Pharmacy, University of Toledo Health Science Campus, Toledo, OH 43614, USA.
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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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Investigating the substrate binding mechanism of sulfotransferase 2A1 based on substrate tunnel analysis: a molecular dynamics simulation study. J Mol Model 2016; 22:176. [DOI: 10.1007/s00894-016-3041-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 06/20/2016] [Indexed: 10/21/2022]
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9
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Astani EK, Heshmati E, Chen CJ, Hadipour NL. A theoretical study on the characteristics of the intermolecular interactions in the active site of human androsterone sulphotransferase: DFT calculations of NQR and NMR parameters and QTAIM analysis. J Mol Graph Model 2016; 68:14-22. [PMID: 27337388 DOI: 10.1016/j.jmgm.2016.06.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 05/29/2016] [Accepted: 06/07/2016] [Indexed: 11/29/2022]
Abstract
A theoretical study at the level of density functional theory (DFT) was performed to characterize noncovalent intermolecular interactions, especially hydrogen bond interactions, in the active site of enzyme human androsterone sulphotransferase (SULT2A1/ADT). Geometry optimization, interaction energy, (2)H, (14)N, and (17)O electric field gradient (EFG) tensors, (1)H, (13)C, (17)O, and (15)N chemical shielding (CS) tensors, Natural Bonding Orbital (NBO) analysis, and quantum theory of atoms in molecules (QTAIM) analysis of this active site were investigated. It was found that androsterone (ADT) is able to form hydrogen bonds with residues Ser80, Ile82, and His99 of the active site. The interaction energy calculations and NBO analysis revealed that the ADT molecule forms the strongest hydrogen bond with Ser80. Results revealed that ADT interacts with the other residues through electrostatic and Van der Waals interactions. Results showed that these hydrogen bonds influence on the calculated (2)H, (14)N, and (17)O quadrupole coupling constants (QCCs), as well as (1)H, (13)C, (17)O, and (15)N CS tensors. The magnitude of the QCC and CS changes at each nucleus depends directly on its amount of contribution to the hydrogen bond interaction.
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Affiliation(s)
- Elahe K Astani
- Department of Chemistry, Faculty of Science, Tarbiat Modares University, Tehran, 14115-175, Iran
| | - Emran Heshmati
- Department of Biology, Faculty of Science, Zanjan University, Zanjan, Iran
| | - Chun-Jung Chen
- Life Science Group, Scientific Research Division, National Synchrotron Radiation Research Center, Taiwan
| | - Nasser L Hadipour
- Department of Chemistry, Faculty of Science, Tarbiat Modares University, Tehran, 14115-175, Iran.
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A study of hydrogen bond effects on the oxygen, nitrogen, and hydrogen electric field gradient tensors in the active site of human dehydroepiandrosterone sulphotransferase: A density-functional theory based treatment. Chem Phys Lett 2016. [DOI: 10.1016/j.cplett.2016.04.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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11
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Astani E, Heshmati E, Chen CJ, Hadipour NL, Shekarsaraei S. Noncovalent intermolecular interactions between dehydroepiandrosterone and the active site of human dehydroepiandrosterone sulphotransferase: A density functional theory based treatment. Chem Phys Lett 2016. [DOI: 10.1016/j.cplett.2016.01.064] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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12
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Ambadapadi S, Wang PL, Palii SP, James MO. Celecoxib influences steroid sulfonation catalyzed by human recombinant sulfotransferase 2A1. J Steroid Biochem Mol Biol 2015; 152:101-13. [PMID: 25960318 PMCID: PMC4501872 DOI: 10.1016/j.jsbmb.2015.05.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 04/30/2015] [Accepted: 05/05/2015] [Indexed: 10/23/2022]
Abstract
Celecoxib has been reported to switch the human SULT2A1-catalyzed sulfonation of 17β-estradiol (17β-E2) from the 3- to the 17-position. The effects of celecoxib on the sulfonation of selected steroids catalyzed by human SULT2A1 were assessed through in vitro and in silico studies. Celecoxib inhibited SULT2A1-catalyzed sulfonation of dehydroepiandrosterone (DHEA), androst-5-ene-3β, 17β-diol (AD), testosterone (T) and epitestosterone (Epi-T) in a concentration-dependent manner. Low μM concentrations of celecoxib strikingly enhanced the formation of the 17-sulfates of 6-dehydroestradiol (6D-E2), 17β-dihydroequilenin (17β-Eqn), 17β-dihydroequilin (17β-Eq), and 9-dehydroestradiol (9D-E2) as well as the overall rate of sulfonation. For 6D-E2, 9D-E2 and 17β-Eqn, celecoxib inhibited 3-sulfonation, however 3-sulfonation of 17β-Eq was stimulated at celecoxib concentrations below 40 μM. Ligand docking studies in silico suggest that celecoxib binds in the substrate-binding site of SULT2A1 in a manner that prohibits the usual binding of substrates but facilitates, for appropriately shaped substrates, a binding mode that favors 17-sulfonation.
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Affiliation(s)
- Sriram Ambadapadi
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville, FL 32610-0485, USA
| | - Peter L Wang
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville, FL 32610-0485, USA
| | - Sergiu P Palii
- Biomedical Mass Spectrometry Laboratory, Clinical Research Center, University of Florida, Gainesville, FL 32610-0322, USA
| | - Margaret O James
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville, FL 32610-0485, USA.
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13
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The impact of ligands on the structure and flexibility of sulfotransferases: a molecular dynamics simulation study. J Mol Model 2015; 21:190. [DOI: 10.1007/s00894-015-2739-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 06/15/2015] [Indexed: 01/11/2023]
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14
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Cook IT, Leyh TS, Kadlubar SA, Falany CN. Lack of substrate inhibition in a monomeric form of human cytosolic SULT2A1. Horm Mol Biol Clin Investig 2015; 3:367-74. [PMID: 25961208 DOI: 10.1515/hmbci.2010.041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2010] [Accepted: 08/16/2010] [Indexed: 11/15/2022]
Abstract
Mammalian cytosolic sulfotransferases (SULTs) frequently show substrate inhibition during the sulfation of increasing concentrations of substrates. SULT2A1, a major human liver isoform responsible for the conjugation of hydroxysteroids, bile acids and aliphatic hydroxyl groups in drugs and xenobiotics, is a homodimer and displays substrate inhibition during the conjugation of dehydroepiandrosterone (DHEA). Maltose binding protein (MBP)-SULT2A1 fusion protein, produced as an intermediate step in the purification of the SULT2A1 homodimer, elutes during size exclusion chromatography as a monomer. The initial-rate parameters (Km and Vmax) of the monomer (MBP-SULT2A1) and native SULT2A1 dimer for DHEA sulfation are extremely similar; however, the monomer is not inhibited by DHEA. Intrinsic fluorescence studies show that two DHEA molecules bind each SULT2A1 subunit, one in the catalytic site and one in an apparent allosteric site. Lack of dimerization in the MBP-SULT2A1 fusion protein decreased the Kd for binding of DHEA at the allosteric site. These results suggest that formation of the homodimer is associated with structural re-arrangements leading to increased DHEA binding at an allo-steric site that is associated with substrate inhibition.
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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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16
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Ekuase EJ, Lehmler HJ, Robertson LW, Duffel MW. Binding interactions of hydroxylated polychlorinated biphenyls (OHPCBs) with human hydroxysteroid sulfotransferase hSULT2A1. Chem Biol Interact 2014; 212:56-64. [PMID: 24508592 PMCID: PMC3994546 DOI: 10.1016/j.cbi.2014.01.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Revised: 01/15/2014] [Accepted: 01/29/2014] [Indexed: 12/15/2022]
Abstract
Polychlorinated biphenyls (PCBs) are persistent environmental contaminants, and exposure to PCBs and their hydroxylated metabolites (OHPCBs) has been associated with various adverse health effects. The mammalian cytosolic sulfotransferases (SULTs) catalyze the sulfation of OHPCBs, and the interaction of OHPCBs with both the SULT1 and SULT2 families of these enzymes has received attention both with respect to metabolic disposition of these molecules and the potential mechanisms for their roles in endocrine disruption. We have previously shown that OHPCBs interact with human hydroxysteroid sulfotransferase hSULT2A1, an enzyme that catalyzes the sulfation of dehydroepiandrosterone (DHEA), other alcohol-containing steroids, bile acids, and many xenobiotics. The objective of our current studies is to investigate the mechanism of inhibition of hSULT2A1 by OHPCBs by combining inhibition kinetics with determination of equilibrium binding constants and molecular modeling of potential interactions. Examination of the effects of fifteen OHPCBs on the sulfation of DHEA catalyzed by hSULT2A1 showed predominantly noncompetitive inhibition patterns. This was observed for OHPCBs that were substrates for sulfation reactions catalyzed by the enzyme as well as those that solely inhibited the sulfation of DHEA. Equilibrium binding experiments and molecular modeling studies indicated that the OHPCBs bind at the binding site for DHEA on the enzyme, and that the observed noncompetitive patterns of inhibition are consistent with binding in more than one orientation to more than one enzyme complex. These results have implications for the roles of SULTs in the toxicology of OHPCBs, while also providing molecular probes of the complexity of substrate/inhibitor interactions with hSULT2A1.
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Affiliation(s)
- Edugie J Ekuase
- Department of Pharmaceutical Sciences and Experimental Therapeutics, College of Pharmacy, University of Iowa, Iowa City, IA 52242, United States
| | - Hans-Joachim Lehmler
- Department of Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City, IA 52242, United States
| | - Larry W Robertson
- Department of Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City, IA 52242, United States
| | - Michael W Duffel
- Department of Pharmaceutical Sciences and Experimental Therapeutics, College of Pharmacy, University of Iowa, Iowa City, IA 52242, United States.
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17
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Cook I, Wang T, Falany CN, Leyh TS. High accuracy in silico sulfotransferase models. J Biol Chem 2013; 288:34494-501. [PMID: 24129576 PMCID: PMC3843064 DOI: 10.1074/jbc.m113.510974] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Revised: 10/06/2013] [Indexed: 12/29/2022] Open
Abstract
Predicting enzymatic behavior in silico is an integral part of our efforts to understand biology. Hundreds of millions of compounds lie in targeted in silico libraries waiting for their metabolic potential to be discovered. In silico "enzymes" capable of accurately determining whether compounds can inhibit or react is often the missing piece in this endeavor. This problem has now been solved for the cytosolic sulfotransferases (SULTs). SULTs regulate the bioactivities of thousands of compounds--endogenous metabolites, drugs and other xenobiotics--by transferring the sulfuryl moiety (SO3) from 3'-phosphoadenosine 5'-phosphosulfate to the hydroxyls and primary amines of these acceptors. SULT1A1 and 2A1 catalyze the majority of sulfation that occurs during human Phase II metabolism. Here, recent insights into the structure and dynamics of SULT binding and reactivity are incorporated into in silico models of 1A1 and 2A1 that are used to identify substrates and inhibitors in a structurally diverse set of 1,455 high value compounds: the FDA-approved small molecule drugs. The SULT1A1 models predict 76 substrates. Of these, 53 were known substrates. Of the remaining 23, 21 were tested, and all were sulfated. The SULT2A1 models predict 22 substrates, 14 of which are known substrates. Of the remaining 8, 4 were tested, and all are substrates. The models proved to be 100% accurate in identifying substrates and made no false predictions at Kd thresholds of 100 μM. In total, 23 "new" drug substrates were identified, and new linkages to drug inhibitors are predicted. It now appears to be possible to accurately predict Phase II sulfonation in silico.
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Affiliation(s)
- Ian Cook
- From the Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461-1926 and
| | - Ting Wang
- From the Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461-1926 and
| | - Charles N. Falany
- the Department of Pharmacology and Toxicology, University of Alabama School of Medicine at Birmingham, Birmingham, Alabama 35294-0019
| | - Thomas S. Leyh
- From the Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461-1926 and
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18
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Qin X, Lehmler HJ, Teesch LM, Robertson LW, Duffel MW. Chlorinated biphenyl quinones and phenyl-2,5-benzoquinone differentially modify the catalytic activity of human hydroxysteroid sulfotransferase hSULT2A1. Chem Res Toxicol 2013; 26:1474-85. [PMID: 24059442 DOI: 10.1021/tx400207q] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Human hydroxysteroid sulfotransferase (hSULT2A1) catalyzes the sulfation of a broad range of environmental chemicals, drugs, and other xenobiotics in addition to endogenous compounds that include hydroxysteroids and bile acids. Polychlorinated biphenyls (PCBs) are persistent environmental contaminants, and oxidized metabolites of PCBs may play significant roles in the etiology of their adverse health effects. Quinones derived from the oxidative metabolism of PCBs (PCB-quinones) react with nucleophilic sites in proteins and also undergo redox cycling to generate reactive oxygen species. This, along with the sensitivity of hSULT2A1 to oxidative modification at cysteine residues, led us to hypothesize that electrophilic PCB-quinones react with hSULT2A1 to alter its catalytic function. Thus, we examined the effects of four phenylbenzoquinones on the ability of hSULT2A1 to catalyze the sulfation of the endogenous substrate, dehydroepiandrosterone (DHEA). The quinones studied were 2'-chlorophenyl-2,5-benzoquinone (2'-Cl-BQ), 4'-chlorophenyl-2,5-benzoquinone (4'-Cl-BQ), 4'-chlorophenyl-3,6-dichloro-2,5-benzoquinone (3,6,4'-triCl-BQ), and phenyl-2,5-benzoquinone (PBQ). At all concentrations examined, pretreatment of hSULT2A1 with the PCB-quinones decreased the catalytic activity of hSULT2A1. Pretreatment with low concentrations of PBQ, however, increased the catalytic activity of the enzyme, while higher concentrations inhibited catalysis. A decrease in substrate inhibition with DHEA was seen following preincubation of hSULT2A1 with all of the quinones. Proteolytic digestion of the enzyme followed by LC/MS analysis indicated PCB-quinone- and PBQ-adducts at Cys55 and Cys199, as well as oxidation products at methionines in the protein. Equilibrium binding experiments and molecular modeling suggested that changes due to these modifications may affect the nucleotide binding site and the entrance to the sulfuryl acceptor binding site of hSULT2A1.
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Affiliation(s)
- Xiaoyan Qin
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa , Iowa City, Iowa 52242, United States
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19
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Leyh TS, Cook I, Wang T. Structure, dynamics and selectivity in the sulfotransferase family. Drug Metab Rev 2013; 45:423-30. [PMID: 24025091 DOI: 10.3109/03602532.2013.835625] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Combined structure, function and molecular dynamics studies of human cytosolic sulfotransferases (SULT1A1 and 2A1) have revealed that these enzymes contain a ≈ 30-residue active-site cap whose structure responds to substrates and mediates their interactions. The binding of 3'-phosphoadenosine 5'-phosphosulfate (PAPS) gates access to the active site by a remodeling of the cap that constricts the pore through which acceptors must pass to enter the active site. While the PAPS-bound enzyme spends the majority (≈ 95%) of its time in the constricted state, the pore isomerizes between the open and closed states when the nucleotide (PAPS) is bound. The dimensions of the open and closed pores place widely different steric constraints on substrate selectivity. Nature appears to have crafted these enzymes with two specificity settings - a closed-pore setting that admits a set of closely related structures, and an open setting that allows a far wider spectrum of acceptor geometries. The specificities of these settings seem well matched to the metabolic demands for homeostatic and defensive SULT functions. The departure of nucleotide requires that the cap open. This isomerization dependent release can explain both the product bursts and substrate inhibition seen in many SULTs. Here, the experimental underpinnings of the cap-mechanism are reviewed, and the advantages of such a mechanism are considered in the context of the cellular and metabolic environment in which these enzymes operate.
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Affiliation(s)
- Thomas S Leyh
- Department of Microbiology and Immunology, Albert Einstein College of Medicine , Bronx, NY , USA
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20
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Qin X, Teesch LM, Duffel MW. Modification of the catalytic function of human hydroxysteroid sulfotransferase hSULT2A1 by formation of disulfide bonds. Drug Metab Dispos 2013; 41:1094-103. [PMID: 23444386 PMCID: PMC3629806 DOI: 10.1124/dmd.112.050534] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Accepted: 02/26/2013] [Indexed: 01/01/2023] Open
Abstract
The human cytosolic sulfotransferase hSULT2A1 catalyzes the sulfation of a broad range of xenobiotics, as well as endogenous hydroxysteroids and bile acids. Reversible modulation of the catalytic activity of this enzyme could play important roles in its physiologic functions. Whereas other mammalian sulfotransferases are known to be reversibly altered by changes in their redox environment, this has not been previously shown for hSULT2A1. We have examined the hypothesis that the formation of disulfide bonds in hSULT2A1 can reversibly regulate the catalytic function of the enzyme. Three thiol oxidants were used as model compounds to investigate their effects on homogeneous preparations of hSULT2A1: glutathione disulfide, 5,5'-dithiobis(2-nitrobenzoic acid), and 1,1'-azobis(N,N-dimethylformamide) (diamide). Examination of the effects of disulfide bond formation with these agents indicated that the activity of the enzyme is reversibly altered. Studies on the kinetics of the hSULT2A1-catalyzed sulfation of dehydroepiandrosterone (DHEA) showed the effects of disulfide bond formation on the substrate inhibition characteristics of the enzyme. The effects of these agents on the binding of substrates and products, liquid chromatography-mass spectrometry identification of the disulfides formed, and structural modeling of the modified enzyme were examined. Our results indicate that conformational changes at cysteines near the nucleotide binding site affect the binding of both the nucleotide and DHEA to the enzyme, with the specific effects dependent on the structure of the resulting disulfide. Thus, the formation of disulfide bonds in hSULT2A1 is a potentially important reversible mechanism for alterations in the rates of sulfation of both endogenous and xenobiotic substrates.
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Affiliation(s)
- Xiaoyan Qin
- Department of Pharmaceutical Sciences and Experimental Therapeutics, College of Pharmacy, The University of Iowa, Iowa City, Iowa, USA
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21
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Cook I, Wang T, Almo SC, Kim J, Falany CN, Leyh TS. Testing the sulfotransferase molecular pore hypothesis. J Biol Chem 2013; 288:8619-8626. [PMID: 23362278 DOI: 10.1074/jbc.m112.445015] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human cytosolic sulfotransferases (SULTs) regulate the activities of hundreds of signaling metabolites via transfer of the sulfuryl moiety (-SO3) from activated sulfate (3'-phosphoadenosine 5'-phosphosulfate) to the hydroxyls and primary amines of xeno- and endobiotics. How SULTs select substrates from the scores of competing ligands present in a cytosolic milieu is an important issue in the field. Selectivity appears to be sterically controlled by a molecular pore that opens and closes in response to nucleotide binding. This point of view is fostered by structures showing nucleotide-dependent pore closure and the fact that nucleotide binding induces an isomerization that restricts access to the acceptor-binding pocket. Molecular dynamics models underscore the importance of pore isomerization in selectivity and predict that specific molecular linkages stabilize the closed pore in response to nucleotide binding. To test the pore model, these linkages were disrupted in SULT2A1 via mutagenesis, and the effects on selectivity were determined. The mutations uncoupled nucleotide binding from selectivity and produced enzymes that no longer discriminated between large and small substrates. The mutations did not affect the affinity or turnover of small substrates but resulted in a 183-fold gain in catalytic efficiently toward large substrates. Models predict that an 11-residue "flap" covering the acceptor-binding pocket can open and admit large substrates when nucleotide is bound; a mutant structure demonstrated that this is so. In summary, the model was shown to be a robust, accurate predictor of SULT structure and selectivity whose general features will likely apply to other members of the SULT family.
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Affiliation(s)
- Ian Cook
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461-1926
| | - Ting Wang
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461-1926
| | - Steven C Almo
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461-1926
| | - Jungwook Kim
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461-1926
| | - Charles N Falany
- Department Pharmacology and Toxicology, University of Alabama School of Medicine, Birmingham, Alabama 35294-0019
| | - Thomas S Leyh
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461-1926.
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22
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Cook I, Wang T, Almo SC, Kim J, Falany CN, Leyh TS. The gate that governs sulfotransferase selectivity. Biochemistry 2012; 52:415-24. [PMID: 23256751 DOI: 10.1021/bi301492j] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Human cytosolic sulfotransferases (SULTs) transfer the sulfuryl moiety (-SO(3)) from activated sulfate [3'-phosphoadenosine 5'-phosphosulfate (PAPS)] to the hydroxyls and primary amines of numerous metabolites, drugs, and xenobiotics. Receipt of the sulfuryl group often radically alters acceptor-target interactions. How these enzymes select particular substrates from the hundreds of candidates in a complex cytosol remains an important question. Recent work reveals PAPS binding causes SULT2A1 to undergo an isomerization that controls selectivity by constricting the opening through which acceptors must pass to enter the active site. The enzyme maintains an affinity for large substrates by isomerizing between the open and closed states with nucleotide bound. Here, the molecular basis of the nucleotide-induced closure is explored in equilibrium and nonequilibrium molecular dynamics simulations. The simulations predict that the active-site "cap," which covers both the nucleotide and acceptor binding sites, opens and closes in response to nucleotide. The cap subdivides into nucleotide and acceptor halves whose motions, while coupled, exhibit an independence that can explain the isomerization. In silico weakening of electrostatic interactions between the cap and base of the active site causes the acceptor half of the cap to open and close while the nucleotide lid remains shut. Simulations predict that SULT1A1, the most abundant SULT in human liver, will utilize a similar selection mechanism. This prediction is tested using fulvestrant, an anti-estrogen too large to pass through the closed pore, and estradiol, which is not restricted by closure. Equilibrium and pre-steady-state binding studies confirm that SULT1A1 undergoes a nucleotide-induced isomerzation that controls substrate selection.
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Affiliation(s)
- Ian Cook
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461-1926, USA
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23
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Cook I, Wang T, Falany CN, Leyh TS. A nucleotide-gated molecular pore selects sulfotransferase substrates. Biochemistry 2012; 51:5674-83. [PMID: 22703301 DOI: 10.1021/bi300631g] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Human SULT2A1 is one of two predominant sulfotransferases in liver and catalyzes transfer of the sulfuryl moiety (-SO(3)) from activated sulfate (PAPS, 3'-phosphoadenosine 5-phosphosulfate) to hundreds of acceptors (metabolites and xenobiotics). Sulfation recodes the biologic activity of acceptors by altering their receptor interactions. The molecular basis on which these enzymes select and sulfonate specific acceptors from complex mixtures of competitors in vivo is a long-standing issue in the SULT field. Raloxifene, a synthetic steroid used in the prevention of osteoporosis, and dehydroepiandrosterone (DHEA), a ubiquitous steroid precusor, are reported to be sulfated efficiently by SULT2A1 in vitro, yet unlike DHEA, raloxifene is not sulfated in vivo. This selectivity was explored in initial rate and equilibrium binding studies that demonstrate pronounced binding antisynergy (21-fold) between PAPS and raloxifene, but not DHEA. Analysis of crystal structures suggests that PAP binding restricts access to the acceptor-binding pocket by restructuring a nine-residue segment of the pocket edge that constricts the active site opening, or "pore", that sieves substrates on the basis of their geometries. In silico docking predicts that raloxifene, which is considerably larger than DHEA, can bind only to the unliganded (open) enzyme, whereas DHEA binds both the open and closed forms. The predictions of these structures with regard to substrate binding are tested using equilibrium and pre-steady-state ligand binding studies, and the results confirm that a nucleotide-driven isomerization controls access to the acceptor-binding pocket and plays an important role in substrate selection by SULT2A1 and possibly other sulfotransferases.
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Affiliation(s)
- Ian Cook
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461-1926, USA
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24
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Dong D, Ako R, Wu B. Crystal structures of human sulfotransferases: insights into the mechanisms of action and substrate selectivity. Expert Opin Drug Metab Toxicol 2012; 8:635-46. [PMID: 22512672 DOI: 10.1517/17425255.2012.677027] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
INTRODUCTION Cytosolic sulfotransferases (SULTs) are the enzymes that catalyze the sulfonation reaction, an important metabolic pathway for numerous endogenous and exogenous compounds. Human SULTs exhibit complex patterns of broad, differential and overlapping substrate selectivity. Moreover, these enzymes often display substrate inhibition kinetics (i.e., inhibition of the enzyme activity at high substrate concentrations). AREAS COVERED At present, the crystal structures for 12 human SULTs (i.e., SULT1A1, 1A2, 1A3, 1B1, 1C1, 1C2, 1C3, 1E1, 2A1, 2B1a, 2B1b and 4A1) are available, many of which are in complex with a substrate. This review describes the similarities and differences in these structures (particularly the active-site structures) of SULT enzymes. The authors also discuss the structural basis for understanding the catalytic mechanism, the substrate inhibition mechanisms, the cofactor (3'-phosphoadenosine 5'-phosphosulfate or PAPS) binding and the substrate recognition. EXPERT OPINION Correlations of the structural features (including conformational flexibility) in the active sites with the substrate profiles of several SULTs have been well established. One is encouraged to closely integrate in silico approaches with the structural knowledge of the active sites for development of a rationalized and accurate tool that is able to predict metabolism of SULTs toward chemicals and drug candidates.
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Affiliation(s)
- Dong Dong
- University of Houston, College of Pharmacy, Department of Pharmacological and Pharmaceutical Sciences, Houston, TX 77030, USA
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25
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Abstract
Inhibition of enzyme activity at high substrate concentrations, so-called "substrate inhibition," is commonly observed and has been recognized in drug metabolism reactions since the last decade. Although the importance of such "atypical" kinetics in vivo remains poorly understood, a substrate with substrate inhibition kinetics has been shown to unconventionally alter the metabolism of other substrates. In recent years, it is becoming increasingly evident that the mechanisms for substrate inhibition are highly complex, which are possibly contributed by multiple (at least two) binding sites within the enzyme protein, the formation of a ternary dead-end enzyme complex, and/or the ligand-induced changes in enzyme conformation. This review primarily discusses the mechanisms for substrate inhibition displayed by the important drug-metabolizing enzymes, such as cytochrome p450s, UDP-glucuronyltransferases, and sulfotransferases. Kinetic modeling of substrate inhibition in the absence or presence of a modifier is another central issue in this review because of its importance in the determination of kinetic parameters and in vitro/in vivo predictions.
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Affiliation(s)
- Baojian Wu
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Texas, USA.
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26
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Gulcan HO, Duffel MW. Substrate inhibition in human hydroxysteroid sulfotransferase SULT2A1: studies on the formation of catalytically non-productive enzyme complexes. Arch Biochem Biophys 2011; 507:232-40. [PMID: 21187059 PMCID: PMC3058861 DOI: 10.1016/j.abb.2010.12.027] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2010] [Revised: 12/20/2010] [Accepted: 12/21/2010] [Indexed: 12/14/2022]
Abstract
The cytosolic sulfotransferase hSULT2A1 is the major hydroxysteroid (alcohol) sulfotransferase in human liver, and it catalyzes the 3'-phosphoadenosine-5'-phosphosulfate (PAPS)-dependent sulfation of various endogenous hydroxysteroids as well as many xenobiotics that contain alcohol and phenol functional groups. The hSULT2A1 often displays substrate inhibition, and we have hypothesized that a key element in this response to increasing substrate concentration is the formation of non-productive ternary dead-end enzyme complexes involving the nucleotide product, adenosine 3',5'-diphosphate (PAP). One of these substrates for hSULT2A1 is dehydroepiandrosterone (DHEA), a major circulating steroid hormone in humans that serves as precursor to both androgens and estrogens. We have utilized DHEA in both initial velocity studies and equilibrium binding experiments in order to evaluate the potential role of ternary complexes in substrate inhibition of the enzyme. Our results indicate that hSULT2A1 forms non-productive ternary complexes that involve either DHEA or dehydroepiandrosterone sulfate, and the formation of these ternary complexes displays negative cooperativity in the binding of DHEA.
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Affiliation(s)
- Hayrettin Ozan Gulcan
- Division of Medicinal and Natural Products Chemistry, College of Pharmacy, The University of Iowa, Iowa City, IA 52242, USA
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27
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Lu J, Li H, Zhang J, Li M, Liu MY, An X, Liu MC, Chang W. Crystal structures of SULT1A2 and SULT1A1 *3: insights into the substrate inhibition and the role of Tyr149 in SULT1A2. Biochem Biophys Res Commun 2010; 396:429-34. [PMID: 20417180 DOI: 10.1016/j.bbrc.2010.04.109] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2010] [Accepted: 04/19/2010] [Indexed: 11/29/2022]
Abstract
The cytosolic sulfotransferases (SULTs) in vertebrates catalyze the sulfonation of endogenous thyroid/steroid hormones and catecholamine neurotransmitters, as well as a variety of xenobiotics, using 3'-phosphoadenosine 5'-phosphosulfate (PAPS) as the sulfonate donor. In this study, we determined the structures of SULT1A2 and an allozyme of SULT1A1, SULT1A1 *3, bound with 3'-phosphoadenosine 5'-phosphate (PAP), at 2.4 and 2.3A resolution, respectively. The conformational differences between the two structures revealed a plastic substrate-binding pocket with two channels and a switch-like substrate selectivity residue Phe247, providing clearly a structural basis for the substrate inhibition. In SULT1A2, Tyr149 extends approximately 2.1A further to the inside of the substrate-binding pocket, compared with the corresponding His149 residue in SULT1A1 *3. Site-directed mutagenesis study showed that, compared with the wild-type SULT1A2, mutant Tyr149Phe SULT1A2 exhibited a 40 times higher K(m) and two times lower V(max) with p-nitrophenol as substrate. These latter data imply a significant role of Tyr149 in the catalytic mechanism of SULT1A2.
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Affiliation(s)
- Jinghua Lu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, People's Republic of China
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28
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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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29
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Cook IT, Leyh TS, Kadlubar SA, Falany CN. Structural rearrangement of SULT2A1: effects on dehydroepiandrosterone and raloxifene sulfation. Horm Mol Biol Clin Investig 2010; 1:81-87. [PMID: 21822452 DOI: 10.1515/hmbci.2010.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND: Human cytosoloic sulfotransferase (SULT) 2A1 is a major hepatic isoform and sulfates hydroxyl groups in structurally diverse sterols and xenobiotics. SULT2A1 crystal structures resolved in the presence and absence of 3',5'-diphosphoadenosine (PAP) or dehydropeiandrosterone (DHEA) suggest a significant rearrangement of the peptide that forms the surface of the active site in the presence of PAP. MATERIALS AND METHODS: Molecular modeling was used to examine the effects of the rearrangement in SULT2A1 associated with 3'-phosphoadenosine 5'-phosphosulfate (PAPS) binding on the binding of DHEA and raloxifene. The kinetics of DHEA and raloxifene sulfation was analyzed to investigate the effects of the rearrangement on SULT2A1 activity. RESULTS: Molecular models indicate that DHEA is able to bind to SULT2A1 in both conformations (open, without PAP; closed, with PAP) in a catalytic configuration, whereas raloxifene bound in a catalytic conformation only in the open structure. Raloxifene did not bind in the smaller, closed substrate binding pocket. Kinetic analysis of DHEA sulfation was consistent with a random Bi-Bi reaction mechanism, whereas raloxifene sulfation was more indicative of an ordered reaction mechanism with raloxifene binding first. Initial burst kinetics with DHEA yielded similar results after preincubation of SULT2A1 with DHEA or PAPS. Preincubation of SULT2A1 with raloxifene showed a burst of raloxifene sulfate formation with the addition of PAPS. In contrast, little raloxifene sulfate was formed if SULT2A1 was preincubated with PAPS and the reaction initiated with raloxifene. CONCLUSIONS: The structural rearrangements in SULT2A1 caused by PAPS binding can alter the sulfation mechanism and kinetics of different substrates.
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Affiliation(s)
- Ian T Cook
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, AL, USA
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30
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Zhang Q, Pi J, Woods CG, Andersen ME. A systems biology perspective on Nrf2-mediated antioxidant response. Toxicol Appl Pharmacol 2009; 244:84-97. [PMID: 19716833 DOI: 10.1016/j.taap.2009.08.018] [Citation(s) in RCA: 157] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2009] [Revised: 08/07/2009] [Accepted: 08/18/2009] [Indexed: 12/13/2022]
Abstract
Cells in vivo are constantly exposed to reactive oxygen species (ROS) generated endogenously and exogenously. To defend against the deleterious consequences of ROS, cells contain multiple antioxidant enzymes expressed in various cellular compartments to scavenge these toxic species. Under oxidative stresses, these antioxidant enzymes are upregulated to restore redox homeostasis. Such an adaptive response results from the activation of a redox-sensitive gene regulatory network mediated by nuclear factor E2-related factor 2. To more completely understand how the redox control system is designed by nature to meet homeostatic goals, we have examined the network from a systems perspective using engineering approaches. As with man-made control devices, the redox control system can be decomposed into distinct functional modules, including transducer, controller, actuator, and plant. Cells achieve specific performance objectives by utilizing nested feedback loops, feedforward control, and ultrasensitive signaling motifs, etc. Given that endogenously generated ROS are also used as signaling molecules, our analysis suggests a novel mode of action to explain oxidative stress-induced pathological conditions and diseases. Specifically, by adaptively upregulating antioxidant enzymes, oxidative stress may inadvertently attenuate ROS signals that mediate physiological processes, resulting in aberrations of cellular functions and adverse consequences. Lastly, by simultaneously considering the two competing cellular tasks-adaptive antioxidant defense and ROS signaling-we re-examine the premise that dietary antioxidant supplements is generally beneficial to human health. Our analysis highlights some possible adverse effects of these widely consumed antioxidants.
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Affiliation(s)
- Qiang Zhang
- Division of Computational Biology, The Hamner Institutes for Health Sciences, 6 Davis Drive, Research Triangle Park, NC 27709, USA.
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Cook IT, Duniec-Dmuchowski Z, Kocarek TA, Runge-Morris M, Falany CN. 24-hydroxycholesterol sulfation by human cytosolic sulfotransferases: formation of monosulfates and disulfates, molecular modeling, sulfatase sensitivity, and inhibition of liver x receptor activation. Drug Metab Dispos 2009; 37:2069-78. [PMID: 19589875 DOI: 10.1124/dmd.108.025759] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
24-Hydroxycholesterol (24-OHChol) is a major cholesterol metabolite and the form in which cholesterol is secreted from the brain. 24-OHChol is transported by apolipoprotein E to the liver and converted into bile acids or excreted. In both brain and liver, 24-OHChol is a liver X receptor (LXR) agonist and has an important role in cholesterol homeostasis. 24-OHChol sulfation was examined to understand its role in 24-OHChol metabolism and its effect on LXR activation. 24-OHChol was conjugated by three isoforms of human cytosolic sulfotransferase (SULT). SULT2A1 and SULT1E1 sulfated both the 3- and 24-hydroxyls to form the 24-OHChol-3, 24-disulfate. SULT2B1b formed only 24-OHChol-3-sulfate. The 3-sulfate as a monosulfate or as the disulfate was hydrolyzed by human placental steroid sulfatase, whereas the 24-sulfate was resistant. At physiological 24-OHChol concentrations, SULT2A1 formed the 3-monosulfate and the 3, 24-disulfate as a result of a high affinity for sulfation of the 3-OH in 24-OHChol-24-sulfate. Molecular docking simulations indicate that 24-OHChol-24-sulfate binds in an active configuration in the SULT2A1 substrate binding site with high affinity only when the SULT2A1 homodimer structure was used. 24-OHChol is an LXR activator. In contrast, the 24-OHChol monosulfates were not LXR agonists in a fluorescence resonance energy transfer coactivator recruitment assay. However, both the 24-OHChol-3-sulfate and 24-sulfate were antagonists of LXR activation by N-(2,2,2-trifluoroethyl)-N-[4-[2,2,2-trif-luoro-1-hydroxy-1-(trifluoromethyl)ethyl]phenyl]-benzenesulfonamide (T0901317) with an IC(50) of 0.15 and 0.31 muM, respectively. Inhibition of LXR activation by the 24-OHChol monosulfates at low nanomolar concentrations indicates that sulfation has a role in LXR regulation by oxysterols.
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Affiliation(s)
- Ian T Cook
- Department of Pharmacology and Toxicology, Volker Hall G133M, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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Weitzner B, Meehan T, Xu Q, Dunbrack RL. An unusually small dimer interface is observed in all available crystal structures of cytosolic sulfotransferases. Proteins 2009; 75:289-95. [PMID: 19173308 DOI: 10.1002/prot.22347] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Cytosolic sulfotransferases catalyze the sulfonation of hormones, metabolites, and xenobiotics. Many of these proteins have been shown to form homodimers and heterodimers. An unusually small dimer interface was previously identified by Petrotchenko et al. (FEBS Lett 2001;490:39-43) by cross-linking, protease digestion, and mass spectrometry and verified by site-directed mutagenesis. Analysis of the crystal packing interfaces in all 28 available crystal structures consisting of 17 crystal forms shows that this interface occurs in all of them. With a small number of exceptions, the publicly available databases of biological assemblies contain either monomers or incorrect dimers. Even crystal structures of mouse SULT1E1, which is a monomer in solution, contain the common dimeric interface, although distorted and missing two important salt bridges.
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Affiliation(s)
- Brian Weitzner
- Institute for Cancer Research, Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, Pennsylvania 19111, USA
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Lu LY, Chiang HP, Chen WT, Yang YS. Dimerization is responsible for the structural stability of human sulfotransferase 1A1. Drug Metab Dispos 2009; 37:1083-8. [PMID: 19237513 DOI: 10.1124/dmd.108.025395] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cytosolic sulfotransferases (SULTs) are responsible for the metabolism of a variety of drugs, xenobiotics, and endogenous compounds. Most cytosolic SULTs are found to be homodimers. However, transformation between monomeric and dimeric SULTs can be achieved by a single amino acid mutation. The importance of quaternary structure for cytosolic sulfotransferase was investigated using recombinant human SULT1A1, a homodimer, and its monomeric mutant (V270E). The differences between dimeric and monomeric SULT1A1 were examined by size-exclusion liquid chromatography, enzyme kinetics, substrate binding affinity, thermal inactivation, conformational stability, and circular dichroism. Variations, especially on their secondary structures and stability, between homodimer and monomer of human SULT1A1 were observed. It was found that the active site of SULT1A1 was not significantly perturbed after the change of its quaternary structure according to SULT1A1 kinetics and substrate binding affinity. However, the stability of monomeric SULT1A1 is significantly decreased. We proposed that the importance of human SULT1A1 as a homodimer was to maintain its structural stability, and the change of secondary structure was responsible for alternating its quaternary structure.
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Affiliation(s)
- Lu-Yi Lu
- Department of Biological Science and Technology, National Chiao Tung University, 75 Po-Ai St., Hsinchu 30050, Taiwan
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34
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Lu LY, Hsieh YC, Liu MY, Lin YH, Chen CJ, Yang YS. Identification and Characterization of Two Amino Acids Critical for the Substrate Inhibition of Human Dehydroepiandrosterone Sulfotransferase (SULT2A1). Mol Pharmacol 2007; 73:660-8. [DOI: 10.1124/mol.107.041038] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
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Allali-Hassani A, Pan PW, Dombrovski L, Najmanovich R, Tempel W, Dong A, Loppnau P, Martin F, Thonton J, Edwards AM, Bochkarev A, Plotnikov AN, Vedadi M, Arrowsmith CH. Structural and chemical profiling of the human cytosolic sulfotransferases. PLoS Biol 2007; 5:e97. [PMID: 17425406 PMCID: PMC1847840 DOI: 10.1371/journal.pbio.0050097] [Citation(s) in RCA: 158] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2006] [Accepted: 02/09/2007] [Indexed: 11/05/2022] Open
Abstract
The human cytosolic sulfotransfases (hSULTs) comprise a family of 12 phase II enzymes involved in the metabolism of drugs and hormones, the bioactivation of carcinogens, and the detoxification of xenobiotics. Knowledge of the structural and mechanistic basis of substrate specificity and activity is crucial for understanding steroid and hormone metabolism, drug sensitivity, pharmacogenomics, and response to environmental toxins. We have determined the crystal structures of five hSULTs for which structural information was lacking, and screened nine of the 12 hSULTs for binding and activity toward a panel of potential substrates and inhibitors, revealing unique "chemical fingerprints" for each protein. The family-wide analysis of the screening and structural data provides a comprehensive, high-level view of the determinants of substrate binding, the mechanisms of inhibition by substrates and environmental toxins, and the functions of the orphan family members SULT1C3 and SULT4A1. Evidence is provided for structural "priming" of the enzyme active site by cofactor binding, which influences the spectrum of small molecules that can bind to each enzyme. The data help explain substrate promiscuity in this family and, at the same time, reveal new similarities between hSULT family members that were previously unrecognized by sequence or structure comparison alone.
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Affiliation(s)
| | - Patricia W Pan
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Ludmila Dombrovski
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
| | - Rafael Najmanovich
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
- European Bioinformatics Institute, Cambridge, United Kingdom
| | - Wolfram Tempel
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
| | - Aiping Dong
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
| | - Peter Loppnau
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
| | - Fernando Martin
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
| | - Janet Thonton
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
- European Bioinformatics Institute, Cambridge, United Kingdom
| | - Aled M Edwards
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
- Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario, Canada
| | - Alexey Bochkarev
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
- Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario, Canada
| | - Alexander N Plotnikov
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Masoud Vedadi
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
| | - Cheryl H Arrowsmith
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
- Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario, Canada
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Shi R, Lamb SS, Bhat S, Sulea T, Wright GD, Matte A, Cygler M. Crystal structure of StaL, a glycopeptide antibiotic sulfotransferase from Streptomyces toyocaensis. J Biol Chem 2007; 282:13073-86. [PMID: 17329243 DOI: 10.1074/jbc.m611912200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Over the past decade, antimicrobial resistance has emerged as a major public health crisis. Glycopeptide antibiotics such as vancomycin and teicoplanin are clinically important for the treatment of Gram-positive bacterial infections. StaL is a 3'-phosphoadenosine 5'-phosphosulfate-dependent sulfotransferase capable of sulfating the cross-linked heptapeptide substrate both in vivo and in vitro, yielding the product A47934, a unique teicoplanin-class glycopeptide antibiotic. The sulfonation reaction catalyzed by StaL constitutes the final step in A47934 biosynthesis. Here we report the crystal structure of StaL and its complex with the cofactor product 3'-phosphoadenosine 5'-phosphate. This is only the second prokaryotic sulfotransferase to be structurally characterized. StaL belongs to the large sulfotransferase family and shows higher similarity to cytosolic sulfotransferases (ST) than to the bacterial ST (Stf0). StaL has a novel dimerization motif, different from any other STs that have been structurally characterized. We have also applied molecular modeling to investigate the binding mode of the unique substrate, desulfo-A47934. Based on the structural analysis and modeling results, a series of residues was mutated and kinetically characterized. In addition to the conserved residues (Lys(12), His(67), and Ser(98)), molecular modeling, fluorescence quenching experiments, and mutagenesis studies identified several other residues essential for substrate binding and/or activity, including Trp(34), His(43), Phe(77), Trp(132), and Glu(205).
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Affiliation(s)
- Rong Shi
- Department of Biochemistry, McGill University, Montréal, Québec H3G 1Y6
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Najmanovich RJ, Allali-Hassani A, Morris RJ, Dombrovsky L, Pan PW, Vedadi M, Plotnikov AN, Edwards A, Arrowsmith C, Thornton JM. Analysis of binding site similarity, small-molecule similarity and experimental binding profiles in the human cytosolic sulfotransferase family. Bioinformatics 2007; 23:e104-9. [PMID: 17237076 DOI: 10.1093/bioinformatics/btl292] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
MOTIVATION In the present work we combine computational analysis and experimental data to explore the extent to which binding site similarities between members of the human cytosolic sulfotransferase family correlate with small-molecule binding profiles. Conversely, from a small-molecule point of view, we explore the extent to which structural similarities between small molecules correlate to protein binding profiles. RESULTS The comparison of binding site structural similarities and small-molecule binding profiles shows that proteins with similar small-molecule binding profiles tend to have a higher degree of binding site similarity but the latter is not sufficient to predict small-molecule binding patterns, highlighting the difficulty of predicting small-molecule binding patterns from sequence or structure. Likewise, from a small-molecule perspective, small molecules with similar protein binding profiles tend to be topologically similar but topological similarity is not sufficient to predict their protein binding patterns. These observations have important consequences for function prediction and drug design.
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Affiliation(s)
- Rafael J Najmanovich
- European Bioinformatics Institute (EMBL-EBI), Wellcome Trust Genome Campus Cambridge CB10 1SD, UK.
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Hoff RH, Czyryca PG, Sun M, Leyh TS, Hengge AC. Transition state of the sulfuryl transfer reaction of estrogen sulfotransferase. J Biol Chem 2006; 281:30645-9. [PMID: 16899461 DOI: 10.1074/jbc.m604205200] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Kinetic isotope effects have been measured for the estrogen sulfotransferase-catalyzed sulfuryl (SO3) transfer from p-nitrophenyl sulfate to the 5'-phosphoryl group of 3'-phosphoadenosine 5'-phosphate. 18(V/K)nonbridge = 1.0016 +/- 0.0005, 18(V/K)bridge = 1.0280 +/- 0.0006, and 15(V/K) = 1.0014 +/- 0.0004. (15(V/K) refers to the nitro group in p-nitrophenyl sulfate). The kinetic isotope effects indicate substantial S O bond fission in the transition state, with partial charge neutralization of the leaving group. The small kinetic isotope effect in the nonbridging sulfuryl oxygen atoms suggests no significant change in bond orders of these atoms occurs, consistent with modest nucleophilic involvement. A comparison of the data for enzymatic and uncatalyzed sulfuryl transfer reactions suggests that both proceed through very similar transition states.
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Affiliation(s)
- Richard H Hoff
- Department of Chemistry and Life Science, United States Military Academy, West Point, New York 10996, USA
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Pi N, Hoang MB, Gao H, Mougous JD, Bertozzi CR, Leary JA. Kinetic measurements and mechanism determination of Stf0 sulfotransferase using mass spectrometry. Anal Biochem 2006; 341:94-104. [PMID: 15866533 DOI: 10.1016/j.ab.2005.02.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2005] [Indexed: 11/26/2022]
Abstract
Mycobacterial carbohydrate sulfotransferase Stf0 catalyzes the sulfuryl group transfer from 3'-phosphoadenosine-5'-phosphosulfate (PAPS) to trehalose. The sulfation of trehalose is required for the biosynthesis of sulfolipid-1, the most abundant sulfated metabolite found in Mycobacterium tuberculosis. In this paper, an efficient enzyme kinetics assay for Stf0 using electrospray ionization (ESI) mass spectrometry is presented. The kinetic constants of Stf0 were measured, and the catalytic mechanism of the sulfuryl group transfer reaction was investigated in initial rate kinetics and product inhibition experiments. In addition, Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry was employed to detect the noncovalent complexes, the Stf0-PAPS and Stf0-trehalose binary complexes, and a Stf0-3'-phosphoadenosine 5'-phosphate-trehalose ternary complex. The results from our study strongly suggest a rapid equilibrium random sequential Bi-Bi mechanism for Stf0 with formation of a ternary complex intermediate. In this mechanism, PAPS and trehalose bind and their products are released in random fashion. To our knowledge, this is the first detailed mechanistic data reported for Stf0, which further demonstrates the power of mass spectrometry in elucidating the reaction pathway and catalytic mechanism of promising enzymatic systems.
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Affiliation(s)
- Na Pi
- Department of Chemistry and Division of Molecular and Cellular Biology, Genome Center, University of California, Davis, CA 95606, USA
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Hildebrandt MAT, Carrington DP, Thomae BA, Eckloff BW, Schaid DJ, Yee VC, Weinshilboum RM, Wieben ED. Genetic diversity and function in the human cytosolic sulfotransferases. THE PHARMACOGENOMICS JOURNAL 2006; 7:133-43. [PMID: 16801938 DOI: 10.1038/sj.tpj.6500404] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Amino-acid substitutions, which result from common nonsynonymous (NS) polymorphisms, may dramatically alter the function of the encoded protein. Gaining insight into how these substitutions alter function is a step toward acquiring predictability. In this study, we incorporated gene resequencing, functional genomics, amino-acid characterization and crystal structure analysis for the cytosolic sulfotransferases (SULTs) to attempt to gain predictability regarding the function of variant allozymes. Previously, four SULT genes were resequenced in 118 DNA samples. With additional resequencing of the remaining eight SULT family members in the same DNA samples, a total of 217 polymorphisms were revealed. Of 64 polymorphisms identified within 8785 bp of coding regions from SULT genes examined, 25 were synonymous and 39 were NS. Overall, the proportion of synonymous changes was greater than expected from a random distribution of mutations, suggesting the presence of a selective pressure against amino-acid substitutions. Functional data for common variants of five SULT genes have been previously published. These data, together with the SULT1A1 variant allozyme data presented in this paper, showed that the major mechanism by which amino acid changes altered function in a transient expression system was through decreases in immunoreactive protein rather than changes in enzyme kinetics. Additional insight with regard to mechanisms by which NS single nucleotide polymorphisms alter function was sought by analysis of evolutionary conservation, physicochemical properties of the amino-acid substitutions and crystal structure analysis. Neither individual amino-acid characteristics nor structural models were able to accurately and reliably predict the function of variant allozymes. These results suggest that common amino-acid substitutions may not dramatically alter the protein structure, but affect interactions with the cellular environment that are currently not well understood.
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Affiliation(s)
- M A T Hildebrandt
- Division of Clinical Pharmacology, Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine, Mayo Foundation, Rochester, MN 55985, USA
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41
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Affiliation(s)
- W Wallace Cleland
- Institute for Enzyme Research and Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53726, USA.
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42
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Kohjitani A, Fuda H, Hanyu O, Strott CA. Cloning, characterization and tissue expression of rat SULT2B1a and SULT2B1b steroid/sterol sulfotransferase isoforms: Divergence of the rat SULT2B1 gene structure from orthologous human and mouse genes. Gene 2006; 367:66-73. [PMID: 16368200 DOI: 10.1016/j.gene.2005.09.009] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2005] [Revised: 08/30/2005] [Accepted: 09/09/2005] [Indexed: 11/24/2022]
Abstract
cDNAs for rat SULT2B1 steroid/sterol sulfotransferase isoforms were cloned, and the encoded proteins overexpressed, purified and characterized. The rat SULT2B1a isoform avidly sulfonates pregnenolone but poorly utilizes cholesterol as a substrate, whereas cholesterol is more efficiently sulfonated than pregnenolone by the SULT2B1b isoform; on the other hand, neither isoform sulfonates dehydroepiandrosterone to any significant degree. Real-time PCR revealed that SULT2B1a was only expressed in brain and testis, whereas SULT2B1b was mainly expressed in skin, intestine and kidney. The SULT2B1 gene is unique among steroid/sterol sulfotransferase genes in that it encodes for two isoforms as a result of an alternative exon I. Interestingly, whereas the orthologous human and mouse SULT2B1 gene structures are identical, the rat SULT2B1 gene structure diverges. Similar to human and mouse SULT2B1 genes the rat SULT2B1 gene consists of an alternative exon I; however, as a result of exonic rearrangement, the genic locations of exons IA and IB are reversed in the rat gene. Where exon IA is located downstream of exon IB in the human and mouse SULT2B1 genes, in the rat SULT2B1 gene exon IA is located upstream of exon IB. Furthermore, unlike the case with human and mouse SULT2B1 genes where differential splicing is necessitated since a portion of exon IA is fused with exon IB to complete the SULT2B1b mRNA, this step is not required with the rat gene.
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Affiliation(s)
- Atsushi Kohjitani
- Section on Steroid Regulation, Endocrinology and Reproduction Research Branch, The National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-4510, USA
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Chatterjee B, Echchgadda I, Song CS. Vitamin D receptor regulation of the steroid/bile acid sulfotransferase SULT2A1. Methods Enzymol 2006; 400:165-91. [PMID: 16399349 DOI: 10.1016/s0076-6879(05)00010-8] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
SULT2A1 is a sulfo-conjugating phase II enzyme expressed at very high levels in the liver and intestine, the two major first-pass metabolic tissues, and in the steroidogenic adrenal tissue. SULT2A1 acts preferentially on the hydroxysteroids dehydroepiandrosterone, testosterone/dihydrotestosterone, and pregnenolone and on cholesterol-derived amphipathic sterol bile acids. Several therapeutic drugs and other xenobiotics, which include xenoestrogens, are also sulfonated by this cytosolic steroid/bile acid sulfotransferase. Nonsteroid nuclear receptors with key roles in the metabolism and detoxification of endobiotics and xenobiotics, such as bile acid-activated farnesoid X receptor, xenobiotic-activated pregnane X receptor and constitutive androstane receptor, and lipid-activated peroxisome proliferator-activated receptor-alpha, mediate transcription induction of SULT2A1 in the enterohepatic system. The ligand-activated vitamin D receptor (VDR) is another nuclear receptor that stimulates SULT2A1 transcription, and the regulatory elements in human, mouse, and rat promoters directing this induction have been characterized. Given that bile acid sulfonation is catalyzed exclusively by SULT2A1 and that the 3alpha-sulfate of the highly toxic lithocholic acid is a major excretory metabolite in humans, we speculate that a role for the VDR pathway in SULT2A1 expression may have emerged to shield first-pass tissues from the cytotoxic effects of a bile acid overload arising from disrupted sterol homeostasis triggered by endogenous and exogenous factors.
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Affiliation(s)
- Bandana Chatterjee
- Department of Molecular Medicine, Institute of Biotechnology, University of Texas Health Science Center at San Antonio and South Texas Veterans Health Care System, USA
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44
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Sinclair PA, Squires EJ. Testicular sulfoconjugation of the 16-androstene steroids by hydroxysteroid sulfotransferase: Its effect on the concentrations of 5α-androstenone in plasma and fat of the mature domestic boar1. J Anim Sci 2005; 83:358-65. [PMID: 15644508 DOI: 10.2527/2005.832358x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
This study examined the relationship between sulfoconjugation and the degree to which 5alpha-androstenone can accumulate in fat. Analysis of the unconjugated and sulfoconjugated fractions of peripheral plasma from 25 mature Yorkshire boars and testicular vein plasma from an additional 20 mature Yorkshire boars revealed that the majority of 5alpha-androstenone is present as a sulfoconjugate, reaching levels up to 69 +/- 4.3 and 72 +/- 6.2%, respectively, relative to its unconjugated form. The presence of this steroid in the sulfoconjugate fraction was confirmed by gas chromatography-mass spectrometry. Plasma concentrations of 5alpha-androstenone in the sulfoconjugate fraction were negatively correlated (r = -0.36; P < 0.01) with the concentrations of 5alpha-androstenone in fat. High concentrations of 5alpha-androstenone in the sulfate fraction were only associated with animals that had fat androstenone concentrations < 0.5 microg/g. In addition, there was a positive correlation (r = 0.31; P < 0.01) between the concentrations of unconjugated 5alpha-androstenone in plasma and 5alpha-androstenone in fat. These findings indicate that the levels of the sulfoconjugated form present in the peripheral plasma influence the accumulation of 5alpha-androstenone in fat. The specific sulfotransferase enzyme involved in sulfoconjugating these steroids was identified by incubating Leydig cells with specific sulfotransferase inhibitors for 8 h. It was discovered that the enzyme responsible for the sulfoconjugation of the 16-androstene steroids is hydroxysteroid sulfotransferase. Hydroxysteroid sulfotransferase may play a significant role in determining the levels of sulfated 16-androstene steroids present in plasma. The results of this study indicate that sulfoconjugation may serve to regulate the quantity of unconjugated 5alpha-androstenone present in the circulation and thus available for accumulation. Animals with a decreased ability to sulfoconjugate 5alpha-androstenone would have a subsequent increase in the levels of unconjugated 5alpha-androstenone in circulation, allowing for the accumulation of high levels in fat and thereby potentially leading to the development of boar taint.
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Affiliation(s)
- P A Sinclair
- Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, Canada, N1G 2W1
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45
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Sharma V, Duffel MW. A Comparative Molecular Field Analysis‐Based Approach to Prediction of Sulfotransferase Catalytic Specificity. Methods Enzymol 2005; 400:249-63. [PMID: 16399353 DOI: 10.1016/s0076-6879(05)00014-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Understanding the catalytic function and substrate specificity of cytosolic sulfotransferases (SULTs) involved in drug metabolism is essential for predicting the metabolic outcomes of many xenobiotics. Although multiple isoforms of cytosolic SULTs have been identified and characterized in humans and other species, relatively little is known about the specific molecular interactions that govern their selectivity for substrates. The use of three-dimensional quantitative structure-activity relationship (3D-QSAR) techniques has emerged as a powerful tool for understanding the relationships among protein structure, catalytic function, and substrate specificity. We have found that a specific adaptation of a ligand-based 3D-QSAR method, comparative molecular field analysis (CoMFA), is particularly useful for prediction of the catalytic efficiencies of SULTs. This approach has been used to study the function of a prototypical rat hepatic phenol SULT and has now been extended to a member of the hydroxysteroid SULT family. Key aspects of this methodology incorporate strategies for finding the most meaningful bioactive conformation with respect to the protein structure, use of a model of an enzyme-substrate complex incorporating the mechanism of sulfuryl transfer, and the utilization of log(k(cat)/K(m)) as the parameter for correlation analysis. The success of this approach with members of two different families of cytosolic SULTs suggests that it may be of more general use in the study of other SULTs.
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Affiliation(s)
- Vyas Sharma
- Division of Medicinal and Natural Products Chemistry, College of Pharmacy, University of Iowa, Iowa City, USA
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Pi N, Yu Y, Mougous JD, Leary JA. Observation of a hybrid random ping-pong mechanism of catalysis for NodST: a mass spectrometry approach. Protein Sci 2004; 13:903-12. [PMID: 15044725 PMCID: PMC2280043 DOI: 10.1110/ps.03581904] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
An efficient enzyme kinetics assay using electrospray ionization mass spectrometry (ESI-MS) was initially applied to the catalytic mechanism investigation of a carbohydrate sulfotransferase, NodST. Herein, the recombinant NodST was overexpressed with a His(6)-tag and purified via Ni-NTA metal-affinity chromatography. In this bisubstrate enzymatic system, an internal standard similar in structure and ionization efficiency to the product was chosen in the ESI-MS assay, and a single point normalization factor was determined and used to quantify the product concentration. The catalytic mechanism of NodST was rapidly determined by fitting the MS kinetic data into a nonlinear regression analysis program. The initial rate kinetics analysis and product inhibition study described support a hybrid double-displacement, two-site ping-pong mechanism of NodST with formation of a sulfated NodST intermediate. This covalent intermediate was further isolated and detected via trypsin digestion and Fourier transform ion cyclotron resonance mass spectrometry. To our knowledge, these are the first mechanistic data reported for the bacterial sulfotransferase, NodST, which demonstrated the power of mass spectrometry in elucidating the reaction pathway and catalytic mechanism of promising enzymatic systems.
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Affiliation(s)
- Na Pi
- Department of Chemistry, University of California, Berkeley, CA 94720, USA
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Tsoi C, Widersten M, Morgenstern R, Swedmark S. Amino acid residue 247 in canine sulphotransferase SULT1D1: a new determinant of substrate selectivity. Biochem J 2004; 378:687-92. [PMID: 14614767 PMCID: PMC1223967 DOI: 10.1042/bj20031470] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2003] [Revised: 11/10/2003] [Accepted: 11/14/2003] [Indexed: 11/17/2022]
Abstract
The SULT (sulphotransferase) family plays a critical role in the detoxification and activation of endogenous and exogenous compounds as well as in the regulation of steroid hormone actions and neurotransmitter functions. The structure-activity relationships of the human SULTs have been investigated with focus on the amino acid 146 in hSULT1A3 and its impact on dopamine/PNP (p-nitrophenol) specificity. In the present study, we have generated canine SULT1D1 (cSULT1D1) variants with mutations at amino acid residues in the substrate-binding pocket [A146E (Ala-146-->Glu), A146D, A146Q, I86D or D247L]. These mutation sites were chosen with regard to their possible contribution to the marked dopamine/PNP preference of cSULT1D1. After characterization, we found that the overall sulphation efficiencies for the cSULT1D1 A146 and the I86 mutants were strongly decreased for both substrates compared with wild-type cSULT1D1 but the substrate preference was unchanged. In contrast, the D247L mutant was found to be more than 21-fold better at sulphating PNP (120-fold decrease in K(m) value) but 54-fold less efficient in sulphating dopamine (8-fold increase in K(m) value) and the preference was switched from dopamine to PNP, indicating the importance of this amino acid in the dopamine/PNP preference in cSULT1D1. Our results show that Asp-247 has a pronounced effect on the substrate specificity of cSULT1D1 and thus we have identified a previously unrecognized contributor to active-site selectivity.
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Affiliation(s)
- Carrie Tsoi
- Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE-171 77 Stockholm, Sweden.
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Chen G. Histidine residues in human phenol sulfotransferases. Biochem Pharmacol 2004; 67:1355-61. [PMID: 15013851 DOI: 10.1016/j.bcp.2003.12.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2003] [Accepted: 12/04/2003] [Indexed: 10/26/2022]
Abstract
Sulfotransferases are phase II drug-metabolizing enzymes that catalyze the sulfation of hydroxyl-containing compounds, leading to detoxification of xenobiotic toxicants. The universal sulfuryl donor is adenosine 3'-phosphate-5'-phosphosulfate. Human simple phenol sulfotransferase (P-PST) is one of the major human sulfotransferases that catalyze the sulfation of most phenols. Human monoamine phenol sulfotransferase (M-PST) has high affinity for monoamines and also catalyzes the sulfation of simple phenols at high substrate concentrations. In this report, the amino acid modification method was used for studies of His residues in the active site of P-PST and M-PST. The His specific modification reagent diethylpyrocarbonate was used for the modification of His residues in P-PST and M-PST. Diethylpyrocarbonate inactivation kinetic data suggest that there is one His residue in the active site that is critical for catalytic activity of both P-PST and M-PST. The modification has no effect on phenol or monoamine substrate binding for M-PST, but it does have an effect on adenosine 3'-phosphate-5'-phosphosulfate binding with M-PST. The experimental results agree with amino acid sequence alignment, mutation, and the crystal structures of P-PST and M-PST and suggest that His108 is the only critical His residue in both P-PST and M-PST. The differing roles His108 plays in P-PST and M-PST may explain the substrate specificity of the two isoforms.
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Affiliation(s)
- Guangping Chen
- Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078, USA.
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Blanchard RL, Freimuth RR, Buck J, Weinshilboum RM, Coughtrie MWH. A proposed nomenclature system for the cytosolic sulfotransferase (SULT) superfamily. ACTA ACUST UNITED AC 2004; 14:199-211. [PMID: 15167709 DOI: 10.1097/00008571-200403000-00009] [Citation(s) in RCA: 224] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
A nomenclature system for the cytosolic sulfotransferase (SULT) superfamily has been developed. The nomenclature guidelines were applied to 65 SULT cDNAs and 18 SULT genes that were characterized from eukaryotic organisms. SULT cDNA and gene sequences were identified by querying the GenBank databases and from published reports of their identification and characterization. These sequences were evaluated and named on the basis of encoded amino acid sequence identity and, in a few cases, a necessity to maintain historical naming convention. Family members share at least 45% amino acid sequence identity whereas subfamily members are at least 60% identical. cDNAs which encode amino acid sequences of at least 97% identity to each other were assigned identical isoform names. We also attempted to categorize orthologous enzymes between various species, where these have been identified, and the nomenclature includes a species descriptor. We present recommendations for the naming of allelic variants of SULT genes and their derived allozymes arising from single nucleotide polymorphisms and other genetic variation. The superfamily currently comprises 47 mammalian SULT isoforms, one insect isoform and eight plant enzymes, and collectively these sequences represent nine separate SULT families and 14 subfamilies. It is hoped that this nomenclature system will be widely adopted and that, as novel SULTs are identified and characterized, investigators will name their discoveries according to these guidelines.
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Affiliation(s)
- Rebecca L Blanchard
- Department of Pharmacology, Fox Chase Cancer Center, Philadelphia, Pennsylvania, USA.
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Barnett AC, Tsvetanov S, Gamage N, Martin JL, Duggleby RG, McManus ME. Active site mutations and substrate inhibition in human sulfotransferase 1A1 and 1A3. J Biol Chem 2004; 279:18799-805. [PMID: 14871892 DOI: 10.1074/jbc.m312253200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human SULT1A1 is primarily responsible for sulfonation of xenobiotics, including the activation of promutagens, and it has been implicated in several forms of cancer. Human SULT1A3 has been shown to be the major sulfotransferase that sulfonates dopamine. These two enzymes shares 93% amino acid sequence identity and have distinct but overlapping substrate preferences. The resolution of the crystal structures of these two enzymes has enabled us to elucidate the mechanisms controlling their substrate preferences and inhibition. The presence of two p-nitrophenol (pNP) molecules in the crystal structure of SULT1A1 was postulated to explain cooperativity at low and inhibition at high substrate concentrations, respectively. In SULT1A1, substrate inhibition occurs with pNP as the substrate but not with dopamine. For SULT1A3, substrate inhibition is found for dopamine but not with pNP. We investigated how substrate inhibition occurs in these two enzymes using molecular modeling, site-directed mutagenesis, and kinetic analysis. The results show that residue Phe-247 of SULT1A1, which interacts with both p-nitrophenol molecules in the active site, is important for substrate inhibition. Mutation of phenylalanine to leucine at this position in SULT1A1 results in substrate inhibition by dopamine. We also propose, based on modeling and kinetic studies, that substrate inhibition by dopamine in SULT1A3 is caused by binding of two dopamine molecules in the active site.
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Affiliation(s)
- Amanda C Barnett
- School of Biomedical Sciences, Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia
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