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Miyauchi Y, Takechi S, Ishii Y. Functional Interaction between Cytochrome P450 and UDP-Glucuronosyltransferase on the Endoplasmic Reticulum Membrane: One of Post-translational Factors Which Possibly Contributes to Their Inter-Individual Differences. Biol Pharm Bull 2021; 44:1635-1644. [PMID: 34719641 DOI: 10.1248/bpb.b21-00286] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cytochrome P450 (P450) and uridine 5'-diphosphate (UDP)-glucuronosyltransferase (UGT) catalyze oxidation and glucuronidation in drug metabolism, respectively. It is believed that P450 and UGT work separately because they perform distinct reactions and exhibit opposite membrane topologies on the endoplasmic reticulum (ER). However, given that some chemicals are sequentially metabolized by P450 and UGT, it is reasonable to consider that the enzymes may interact and work cooperatively. Previous research by our team detected protein-protein interactions between P450 and UGT by analyzing solubilized rat liver microsomes with P450-immobilized affinity column chromatography. Although P450 and UGT have been known to form homo- and hetero-oligomers, this is the first report indicating a P450-UGT association. Based on our previous study, we focused on the P450-UGT interaction and reported lines of evidence that the P450-UGT association is a functional protein-protein interaction that can alter the enzymatic capabilities, including enhancement or suppression of the activities of P450 and UGT, helping UGT to acquire novel regioselectivity, and inhibiting substrate binding to P450. Biochemical and molecular bioscientific approaches suggested that P450 and UGT interact with each other at their internal hydrophobic domains in the ER membrane. Furthermore, several in vivo studies have reported the presence of a functional P450-UGT association under physiological conditions. The P450-UGT interaction is expected to function as a novel post-translational factor for inter-individual differences in the drug-metabolizing enzymes.
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Affiliation(s)
- Yuu Miyauchi
- Laboratory of Hygienic Chemistry, Faculty of Pharmaceutical Sciences, Sojo University.,Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences, Kyushu University
| | - Shinji Takechi
- Laboratory of Hygienic Chemistry, Faculty of Pharmaceutical Sciences, Sojo University
| | - Yuji Ishii
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences, Kyushu University.,Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences, Kyushu University
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Miyauchi Y, Kurohara K, Kimura A, Esaki M, Fujimoto K, Hirota Y, Takechi S, Mackenzie PI, Ishii Y, Tanaka Y. The carboxyl-terminal di-lysine motif is essential for catalytic activity of UDP-glucuronosyltransferase 1A9. Drug Metab Pharmacokinet 2020; 35:466-474. [PMID: 32883578 DOI: 10.1016/j.dmpk.2020.07.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 07/29/2020] [Accepted: 07/29/2020] [Indexed: 11/25/2022]
Abstract
UDP-Glucuronosyltransferase (UGT) is a type I membrane protein localized to the endoplasmic reticulum (ER). UGT has a di-lysine motif (KKXX/KXKXX) in its cytoplasmic domain, which is defined as an ER retention signal. However, our previous study has revealed that UGT2B7, one of the major UGT isoform in human, localizes to the ER in a manner that is independent of this motif. In this study, we focused on another UGT isoform, UGT1A9, and investigated the role of the di-lysine motif in its ER localization, glucuronidation activity, and homo-oligomer formation. Immunofluorescence microscopy indicated that the cytoplasmic domain of UGT1A9 functioned as an ER retention signal in a chimeric protein with CD4, but UGT1A9 itself could localize to the ER in a di-lysine motif-independent manner. In addition, UGT1A9 formed homo-oligomers in the absence of the motif. However, deletion of the di-lysine motif or substitution of lysines in the motif for alanines, severely impaired glucuronidation activity of UGT1A9. This is the first study that re-defines the cytoplasmic di-lysine motif of UGT as an essential peptide for retaining glucuronidation capacity.
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Affiliation(s)
- Yuu Miyauchi
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan; Laboratory of Hygienic Chemistry, Faculty of Pharmaceutical Sciences, Sojo University, Kumamoto, Japan.
| | - Ken Kurohara
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Akane Kimura
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Madoka Esaki
- Laboratory of Hygienic Chemistry, Faculty of Pharmaceutical Sciences, Sojo University, Kumamoto, Japan
| | - Keiko Fujimoto
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Yuko Hirota
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Shinji Takechi
- Laboratory of Hygienic Chemistry, Faculty of Pharmaceutical Sciences, Sojo University, Kumamoto, Japan
| | - Peter I Mackenzie
- Clinical Pharmacology, College of Medicine and Public Health, Flinders Medical Centre and Flinders University, Adelaide, Australia
| | - Yuji Ishii
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan; Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan.
| | - Yoshitaka Tanaka
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
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Miyauchi Y, Tanaka Y, Nagata K, Yamazoe Y, Mackenzie PI, Yamada H, Ishii Y. UDP-Glucuronosyltransferase (UGT)-mediated attenuations of cytochrome P450 3A4 activity: UGT isoform-dependent mechanism of suppression. Br J Pharmacol 2019; 177:1077-1089. [PMID: 31660580 DOI: 10.1111/bph.14900] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2018] [Revised: 09/19/2019] [Accepted: 09/28/2019] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND AND PURPOSE Cytochrome P450 (CYP, P450) 3A4 is involved in the metabolism of 50% of drugs and its catalytic activity in vivo is not explained only by hepatic expression levels. We previously demonstrated that UDP-glucuronosyltransferase (UGT) 2B7 suppressed CYP3A4 activity through an interaction. In the present study, we target UGT1A9 as another candidate modulator of CYP3A4. EXPERIMENTAL APPROACH We prepared co-expressed enzymes using the baculovirus-insect cell expression system and compared CYP3A4 activity in the presence and absence of UGT1A9. Wistar rats were treated with dexamethasone and liver microsomes were used to elucidate the role of CYP3A-UGT1A interactions. KEY RESULTS UGT1A9 and UGT2B7 interacted with and suppressed CYP3A4. Kinetic analyses showed that both of the UGTs significantly reduced Vmax of CYP3A4 activity. In addition, C-terminal truncated mutants of UGT1A9 and UGT2B7 still retained the suppressive capacity. Dexamethasone treatment induced hepatic CYP3As and UGT1As at different magnitudes. Turnover of CYP3A was enhanced about twofold by this treatment. CONCLUSION AND IMPLICATIONS The changes of kinetic parameters suggested that UGT1A9 suppressed CYP3A4 activity with almost the same mechanism as UGT2B7. The luminal domain of UGTs contains the suppressive interaction site(s), whereas the C-terminal domain may contribute to modulating suppression in a UGT isoform-specific manner. CYP3A-UGT1A interaction seemed to be disturbed by dexamethasone treatment and the suppression was partially cancelled. CYP3A4-UGT interactions would help to better understand the causes of inter/intra-individual differences in CYP3A4 activity.
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Affiliation(s)
- Yuu Miyauchi
- Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan.,Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Yoshitaka Tanaka
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Kiyoshi Nagata
- Department of Environmental and Health Science, School of Pharmaceutical Sciences, Tohoku Medical and Pharmaceutical University, Sendai, Japan
| | - Yasushi Yamazoe
- Food Safety Commission, Cabinet Office, Government of Japan, Tokyo, Japan
| | - Peter I Mackenzie
- Department of Clinical Pharmacology, Flinders Medical Centre and Flinders University, Adelaide, SA, Australia
| | - Hideyuki Yamada
- Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Yuji Ishii
- Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
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Miyauchi Y, Kimura S, Kimura A, Kurohara K, Hirota Y, Fujimoto K, Mackenzie PI, Tanaka Y, Ishii Y. Investigation of the Endoplasmic Reticulum Localization of UDP-Glucuronosyltransferase 2B7 with Systematic Deletion Mutants. Mol Pharmacol 2019; 95:551-562. [PMID: 30944207 DOI: 10.1124/mol.118.113902] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 03/05/2019] [Indexed: 11/22/2022] Open
Abstract
UDP-Glucuronosyltransferase (UGT) plays an important role in the metabolism of endogenous and exogenous compounds. UGT is a type I membrane protein, and has a dilysine motif (KKXX/KXKXX) in its C-terminal cytoplasmic domain. Although a dilysine motif is defined as an endoplasmic reticulum (ER) retrieval signal, it remains a matter of debate whether this motif functions in the ER localization of UGT. To address this issue, we generated systematic deletion mutants of UGT2B7, a major human isoform, and compared their subcellular localizations with that of an ER marker protein calnexin (CNX), using subcellular fractionation and immunofluorescent microscopy. We found that although the dilysine motif functioned as the ER retention signal in a chimera that replaced the cytoplasmic domain of CD4 with that of UGT2B7, UGT2B7 truncated mutants lacking this motif extensively colocalized with CNX, indicating dilysine motif-independent ER retention of UGT2B7. Moreover, deletion of the C-terminal transmembrane and cytoplasmic domains did not affect ER localization of UGT2B7, suggesting that the signal necessary for ER retention of UGT2B7 is present in its luminal domain. Serial deletions of the luminal domain, however, did not affect the ER retention of the mutants. Further, a cytoplasmic and transmembrane domain-deleted mutant of UGT2B7 was localized to the ER without being secreted. These results suggest that UGT2B7 could localize to the ER without any retention signal, and lead to the conclusion that the static localization of UGT results from lack of a signal for export from the ER.
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Affiliation(s)
- Yuu Miyauchi
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences (Y.M., A.K., K.K., Y.H., K.F., Y.T.) and Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences (Y.M., S.K., Y.I.), Kyushu University, Fukuoka, Japan; and Department of Clinical Pharmacology, Flinders Medical Centre and Flinders University, Adelaide, South Australia, Australia (P.I.M.)
| | - Sora Kimura
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences (Y.M., A.K., K.K., Y.H., K.F., Y.T.) and Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences (Y.M., S.K., Y.I.), Kyushu University, Fukuoka, Japan; and Department of Clinical Pharmacology, Flinders Medical Centre and Flinders University, Adelaide, South Australia, Australia (P.I.M.)
| | - Akane Kimura
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences (Y.M., A.K., K.K., Y.H., K.F., Y.T.) and Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences (Y.M., S.K., Y.I.), Kyushu University, Fukuoka, Japan; and Department of Clinical Pharmacology, Flinders Medical Centre and Flinders University, Adelaide, South Australia, Australia (P.I.M.)
| | - Ken Kurohara
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences (Y.M., A.K., K.K., Y.H., K.F., Y.T.) and Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences (Y.M., S.K., Y.I.), Kyushu University, Fukuoka, Japan; and Department of Clinical Pharmacology, Flinders Medical Centre and Flinders University, Adelaide, South Australia, Australia (P.I.M.)
| | - Yuko Hirota
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences (Y.M., A.K., K.K., Y.H., K.F., Y.T.) and Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences (Y.M., S.K., Y.I.), Kyushu University, Fukuoka, Japan; and Department of Clinical Pharmacology, Flinders Medical Centre and Flinders University, Adelaide, South Australia, Australia (P.I.M.)
| | - Keiko Fujimoto
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences (Y.M., A.K., K.K., Y.H., K.F., Y.T.) and Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences (Y.M., S.K., Y.I.), Kyushu University, Fukuoka, Japan; and Department of Clinical Pharmacology, Flinders Medical Centre and Flinders University, Adelaide, South Australia, Australia (P.I.M.)
| | - Peter I Mackenzie
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences (Y.M., A.K., K.K., Y.H., K.F., Y.T.) and Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences (Y.M., S.K., Y.I.), Kyushu University, Fukuoka, Japan; and Department of Clinical Pharmacology, Flinders Medical Centre and Flinders University, Adelaide, South Australia, Australia (P.I.M.)
| | - Yoshitaka Tanaka
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences (Y.M., A.K., K.K., Y.H., K.F., Y.T.) and Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences (Y.M., S.K., Y.I.), Kyushu University, Fukuoka, Japan; and Department of Clinical Pharmacology, Flinders Medical Centre and Flinders University, Adelaide, South Australia, Australia (P.I.M.)
| | - Yuji Ishii
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences (Y.M., A.K., K.K., Y.H., K.F., Y.T.) and Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences (Y.M., S.K., Y.I.), Kyushu University, Fukuoka, Japan; and Department of Clinical Pharmacology, Flinders Medical Centre and Flinders University, Adelaide, South Australia, Australia (P.I.M.)
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Protein-protein interactions between the bilirubin-conjugating UDP-glucuronosyltransferase UGT1A1 and its shorter isoform 2 regulatory partner derived from alternative splicing. Biochem J 2013; 450:107-14. [PMID: 23148825 DOI: 10.1042/bj20121594] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The oligomerization of UGTs [UDP (uridine diphosphate)-glucuronosyltransferases] modulates their enzyme activities. Recent findings also indicate that glucuronidation is negatively regulated by the formation of inactive oligomeric complexes between UGT1A enzymes [i1 (isoform 1)] and an enzymatically inactive alternatively spliced i2 (isoform 2). In the present paper, we assessed whether deletion of the UGT-interacting domains previously reported to be critical for enzyme function might be involved in i1-i2 interactions. The bilirubin-conjugating UGT1A1 was used as a prototype. We also explored whether intermolecular disulfide bonds are involved in i1-i2 interactions and the potential role of selected cysteine residues. Co-immunoprecipitation assays showed that UGT1A1 lacking the SP (signal peptide) alone or also lacking the transmembrane domain (absent from i2) did not self-interact, but still interacted with i2. The deletion of other N- or C-terminal domains did not compromise i1-i2 complex formation. Under non-reducing conditions, we also observed formation of HMWCs (high-molecular-mass complexes) for cells overexpressing i1 and i2. The presence of UGTs in these complexes was confirmed by MS. Mutation of individual cysteine residues throughout UGT1A1 did not compromise i1-i1 or i1-i2 complex formation. These findings are compatible with the hypothesis that the interaction between i1 and i2 proteins (either transient or stable) involves binding of more than one domain that probably differs from those involved in i1-i1 interactions.
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Ishii Y, Takeda S, Yamada H. Modulation of UDP-glucuronosyltransferase activity by protein-protein association. Drug Metab Rev 2010; 42:145-58. [PMID: 19817679 DOI: 10.3109/03602530903208579] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Drug oxidation and conjugation mediated by cytochrome P450 (P450) and UDP-glucuronosyltransferase (UGT) have long been considered to take place separately. However, our recent studies have suggested that CYP3A4 specifically associates with UGT2B7 and alters the regioselectivity of morphine glucuronidation. This observation strongly supports the view that there is functional cooperation between P450 and UGT to facilitate multistep drug metabolism. In recent years, accumulating evidence has suggested an interaction between UGT isoforms or between P450 and UGTs and a change in UGT function by protein-protein association. In this review, we summarize these interactions and discuss their relevance to UGT function.
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Affiliation(s)
- Yuji Ishii
- Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan.
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7
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Laakkonen L, Finel M. A molecular model of the human UDP-glucuronosyltransferase 1A1, its membrane orientation, and the interactions between different parts of the enzyme. Mol Pharmacol 2010; 77:931-9. [PMID: 20215562 DOI: 10.1124/mol.109.063289] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The vertebrate UDP-glucuronosyltransferases (UGTs) are membrane-bound enzymes of the endoplasmic reticulum that process both endogenous and exogenous substrates. The human UGTs are well known biologically, but biophysical understanding is scarce, largely because of problems in purification. The one resolved crystal structure covers the C-terminal domain of the human UGT2B7. Here, we present a homology model of the complete monomeric human UGT1A1, the enzyme that catalyzes bilirubin glucuronidation. The enzyme can be seen as composed of four different domains: two large ones, the N- and C-terminal domains, and two small ones, the "envelope" helices and the transmembrane segment that includes the cytoplasmic tail. The hydrophobic core of the N-terminal domain and the two envelope helices that connect the large domains are shown to be structurally well conserved even among distant homologs and can thus be modeled with good certainty according to plant and bacterial structures. We consider alternative solutions for the highly variable N-terminal regions that probably contribute to substrate binding. The bilirubin binding site, known pathological mutations in UGT1A1, and other specific residues have been examined in the context of the model with regard to available experimental data. A putative orientation of the protein relative to the membrane has been derived from the location of predicted N-glycosylation sites. The model presents extensive interactions between the N- and C-terminal domains, the two envelope helices, and the membrane. Together, these interactions could allow for a concerted large-scale conformational change during catalysis.
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Affiliation(s)
- Liisa Laakkonen
- Centre for Drug Research, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
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8
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Trubetskoy O, Finel M, Trubetskoy V. High-throughput screening technologies for drug glucuronidation profiling. J Pharm Pharmacol 2010; 60:1061-7. [DOI: 10.1211/jpp.60.8.0012] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Abstract
A significant number of endogenous and exogenous compounds, including many therapeutic agents, are metabolized in humans via glucuronidation, catalysed by uridine diphosphoglucurono-syltransferases (UGTs). The study of the UGTs is a growing field of research, with constantly accumulated and updated information regarding UGT structure, purification, substrate specificity and inhibition, including clinically relevant drug interactions. Development of reliable UGT assays for the assessment of individual isoform substrate specificity and for the discovery of novel isoform-specific substrates and inhibitors is crucial for understanding the function and regulation of the UGT enzyme family and its clinical and pharmacological relevance. High-throughput screening (HTS) is a powerful technology used to search for novel substrates and inhibitors for a wide variety of targets. However, application of HTS in the context of UGTs is complicated because of the poor stability, low levels of expression, low affinity and broad substrate specificity of the enzymes, combined with difficulties in obtaining individual UGT isoforms in purified format, and insufficient information regarding isoform-specific substrates and inhibitors. This review examines the current status of HTS assays used in the search for novel UGT substrates and inhibitors, emphasizing advancements and challenges in HTS technologies for drug glucuronidation profiling, and discusses possible avenues for future advancement of the field.
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Affiliation(s)
- Olga Trubetskoy
- School of Pharmacy, University of Wisconsin, Madison, Wisconsin, USA
| | - Moshe Finel
- DDTC, Faculty of Pharmacy, University of Helsinki, Finland
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9
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Patana AS, Kurkela M, Finel M, Goldman A. Mutation analysis in UGT1A9 suggests a relationship between substrate and catalytic residues in UDP-glucuronosyltransferases. Protein Eng Des Sel 2008; 21:537-43. [PMID: 18502788 DOI: 10.1093/protein/gzn030] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
UDP-glucuronosyltransferases (UGTs) catalyze the transfer of glucuronic acid from UDP-glucuronic acid to endo- and xenobiotics in our body. UGTs belong to the GT1 family of glycosyltransferases and many GT1s use a serine protease-like catalytic mechanism in which an Asp-His pair deprotonates a hydroxyl on the aglycone for nucleophilic attack on the sugar donor. The pair in human UGTs could be H37 and either D143 or D148 (UGT1A9 numbering). However, H37 is not totally conserved, being replaced by either Pro or Leu in UGT1A4 and UGT2B10. We therefore investigated the role of H37, D143 and D148 in UGT1A9 by site-directed mutagenesis, activity and kinetic measurements with several substrates. The results suggest that H37 is not critical in N-glucuronidation, but is so in O-glucuronidation. The V(max) of the H37A mutant was much less affected in N- than O-glucuronidation, while the reverse was true for the Asp mutations, particularly D143A. We suggest that this is due to the opposing properties of O- and N- nucleophiles. O-nucleophiles require the histidine to deprotonate them so that they become effective nucleophiles, while N-nucleophiles develop a formal positive charge during the reaction (RNH(2)(+)-GlcA), and thus require a negatively charged residue to stabilize the transition state.
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Affiliation(s)
- Anne-Sisko Patana
- Structural Biology and Biophysics, Institute of Biotechnology, University of Helsinki, Biocenter 3, PO Box 65, Viikinkaari 1, FIN-00014 Helsinki, Finland
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10
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Iyanagi T. Molecular mechanism of phase I and phase II drug-metabolizing enzymes: implications for detoxification. ACTA ACUST UNITED AC 2007; 260:35-112. [PMID: 17482904 DOI: 10.1016/s0074-7696(06)60002-8] [Citation(s) in RCA: 157] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Enzymes that catalyze the biotransformation of drugs and xenobiotics are generally referred to as drug-metabolizing enzymes (DMEs). DMEs can be classified into two main groups: oxidative or conjugative. The NADPH-cytochrome P450 reductase (P450R)/cytochrome P450 (P450) electron transfer systems are oxidative enzymes that mediate phase I reactions, whereas the UDP-glucuronosyltransferases (UGTs) are conjugative enzymes that mediate phase II enzymes. Both enzyme systems are localized to the endoplasmic reticulum (ER) where a number of drugs are sequentially metabolized. DMEs, including P450s and UGTs, generally have a highly plastic active site that can accommodate a wide variety of substrates. The P450 and UGT genes constitute a supergene family, in which UGT proteins are encoded by distinct genes and a complex gene. Both the P450 and UGT genes have evolved to diversify their functions. This chapter reviews advances in understanding the structure and function of the P450R/P450 and UGT enzyme systems. In particular, the coordinate biotransformation of xenobiotics by phase I and II enzymes in the ER membrane is examined.
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Affiliation(s)
- Takashi Iyanagi
- Biometal Science Laboratory, RIKEN SPring-8 Center, Harima Institute, Hyogo 679-5148, Japan
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11
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Locuson CW, Tracy TS. Comparative modelling of the human UDP-glucuronosyltransferases: insights into structure and mechanism. Xenobiotica 2007; 37:155-68. [PMID: 17484518 DOI: 10.1080/00498250601129109] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
UDP-glucuronosyltranferases (UGTs) affect the disposition of drugs and other xenobiotics by catalysing the conjugation of glucuronic acid to available oxygen, nitrogen, and sulfur atoms. Several related mammalian isoforms of UGT are expressed that have different binding affinities and turnover rates for the substrates they encounter in the liver and other tissues. Because no high-resolution structural information is available to dissect the enzyme-substrate interactions that give rise to different specificities, a search was conducted to find the best available templates to use for comparative protein modelling. Sequence identity analysis was used to identify some recently crystallized plant UGTs as homologues of microsomal UGTs. Because UGTs contain a Rossman fold motif predicted to bind the UDP-containing sugar donor substrate, this consensus sequence was used to aid sequence alignment, as were other conserved residues thought to be involved in catalysis or substrate binding, and the predicted secondary structure. Docking of UDP-glucuronic acid to a model of UGT1A1 resulted in a root mean square deviation of only 0.37 angstroms vs. UDP co-crystallized with the plant UGT71G1 template. The significance of a comparative model generated for UGT1A1 with respect to both the sugar donor and aglycone binding sites, and mechanism, is discussed.
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Affiliation(s)
- C W Locuson
- Pfizer Animal Health, Veterinary Medicine Research and Development, Metabolism and Safety, Kalamazoo, MI 49007, USA.
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12
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Tress ML, Martelli PL, Frankish A, Reeves GA, Wesselink JJ, Yeats C, Ólason PĹ, Albrecht M, Hegyi H, Giorgetti A, Raimondo D, Lagarde J, Laskowski RA, López G, Sadowski MI, Watson JD, Fariselli P, Rossi I, Nagy A, Kai W, Størling Z, Orsini M, Assenov Y, Blankenburg H, Huthmacher C, Ramírez F, Schlicker A, Denoeud F, Jones P, Kerrien S, Orchard S, Antonarakis SE, Reymond A, Birney E, Brunak S, Casadio R, Guigo R, Harrow J, Hermjakob H, Jones DT, Lengauer T, A. Orengo C, Patthy L, Thornton JM, Tramontano A, Valencia A. The implications of alternative splicing in the ENCODE protein complement. Proc Natl Acad Sci U S A 2007; 104:5495-500. [PMID: 17372197 PMCID: PMC1838448 DOI: 10.1073/pnas.0700800104] [Citation(s) in RCA: 160] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2006] [Indexed: 12/22/2022] Open
Abstract
Alternative premessenger RNA splicing enables genes to generate more than one gene product. Splicing events that occur within protein coding regions have the potential to alter the biological function of the expressed protein and even to create new protein functions. Alternative splicing has been suggested as one explanation for the discrepancy between the number of human genes and functional complexity. Here, we carry out a detailed study of the alternatively spliced gene products annotated in the ENCODE pilot project. We find that alternative splicing in human genes is more frequent than has commonly been suggested, and we demonstrate that many of the potential alternative gene products will have markedly different structure and function from their constitutively spliced counterparts. For the vast majority of these alternative isoforms, little evidence exists to suggest they have a role as functional proteins, and it seems unlikely that the spectrum of conventional enzymatic or structural functions can be substantially extended through alternative splicing.
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Affiliation(s)
- Michael L. Tress
- Structural Computational Biology Programme, Spanish National Cancer Research Centre, E-28029 Madrid, Spain
| | | | - Adam Frankish
- HAVANA Group, The Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, United Kingdom
| | - Gabrielle A. Reeves
- European Bioinformatics Institute, Hinxton, Cambridge CB10 1SD, United Kingdom
| | - Jan Jaap Wesselink
- Structural Computational Biology Programme, Spanish National Cancer Research Centre, E-28029 Madrid, Spain
| | - Corin Yeats
- Department of Biochemistry and Molecular Biology and
| | - Páll ĺsólfur Ólason
- Center for Biological Sequence Analysis, BioCentrum-DTU, DK-2800 Lyngby, Denmark
| | - Mario Albrecht
- Max Planck Institute for Informatics, 66123 Saarbrücken, Germany
| | - Hedi Hegyi
- Biological Research Center, Hungarian Academy of Sciences, 1113 Budapest, Hungary
| | - Alejandro Giorgetti
- Department of Biochemical Sciences, University of Rome “La Sapienza,” 2-00185 Rome, Italy
| | - Domenico Raimondo
- Department of Biochemical Sciences, University of Rome “La Sapienza,” 2-00185 Rome, Italy
| | - Julien Lagarde
- Research Unit on Biomedical Informatics, Institut Municipal d'Investigació Mèdica, E-8003 Barcelona, Spain
| | - Roman A. Laskowski
- European Bioinformatics Institute, Hinxton, Cambridge CB10 1SD, United Kingdom
| | - Gonzalo López
- Structural Computational Biology Programme, Spanish National Cancer Research Centre, E-28029 Madrid, Spain
| | - Michael I. Sadowski
- Bioinformatics Unit, University College London, London WC1E 6BT, United Kingdom
| | - James D. Watson
- European Bioinformatics Institute, Hinxton, Cambridge CB10 1SD, United Kingdom
| | - Piero Fariselli
- Department of Biology, University of Bologna, 33-40126 Bologna, Italy
| | - Ivan Rossi
- Department of Biology, University of Bologna, 33-40126 Bologna, Italy
| | - Alinda Nagy
- Biological Research Center, Hungarian Academy of Sciences, 1113 Budapest, Hungary
| | - Wang Kai
- Center for Biological Sequence Analysis, BioCentrum-DTU, DK-2800 Lyngby, Denmark
| | - Zenia Størling
- Center for Biological Sequence Analysis, BioCentrum-DTU, DK-2800 Lyngby, Denmark
| | - Massimiliano Orsini
- Center for Advanced Studies, Research and Development in Sardinia (CRS4), 09010 Pula, Italy
| | - Yassen Assenov
- Max Planck Institute for Informatics, 66123 Saarbrücken, Germany
| | | | | | - Fidel Ramírez
- Max Planck Institute for Informatics, 66123 Saarbrücken, Germany
| | | | - France Denoeud
- Research Unit on Biomedical Informatics, Institut Municipal d'Investigació Mèdica, E-8003 Barcelona, Spain
| | - Phil Jones
- European Bioinformatics Institute, Hinxton, Cambridge CB10 1SD, United Kingdom
| | - Samuel Kerrien
- European Bioinformatics Institute, Hinxton, Cambridge CB10 1SD, United Kingdom
| | - Sandra Orchard
- European Bioinformatics Institute, Hinxton, Cambridge CB10 1SD, United Kingdom
| | - Stylianos E. Antonarakis
- Department of Genetic Medicine and Development, University of Geneva Medical School, 1211 Geneva, Switzerland
| | - Alexandre Reymond
- Center for Integrative Genomics, Genopode building, University of Lausanne, 1015 Lausanne, Switzerland; and
| | - Ewan Birney
- European Bioinformatics Institute, Hinxton, Cambridge CB10 1SD, United Kingdom
| | - Søren Brunak
- Center for Biological Sequence Analysis, BioCentrum-DTU, DK-2800 Lyngby, Denmark
| | - Rita Casadio
- Department of Biology, University of Bologna, 33-40126 Bologna, Italy
| | - Roderic Guigo
- Research Unit on Biomedical Informatics, Institut Municipal d'Investigació Mèdica, E-8003 Barcelona, Spain
- Centre de Regulació Genòmica, Universitat Pompeu Fabra, E-08003 Barcelona, Spain
| | - Jennifer Harrow
- HAVANA Group, The Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, United Kingdom
| | - Henning Hermjakob
- European Bioinformatics Institute, Hinxton, Cambridge CB10 1SD, United Kingdom
| | - David T. Jones
- Bioinformatics Unit, University College London, London WC1E 6BT, United Kingdom
| | - Thomas Lengauer
- Max Planck Institute for Informatics, 66123 Saarbrücken, Germany
| | | | - László Patthy
- Biological Research Center, Hungarian Academy of Sciences, 1113 Budapest, Hungary
| | - Janet M. Thornton
- European Bioinformatics Institute, Hinxton, Cambridge CB10 1SD, United Kingdom
| | | | - Alfonso Valencia
- Structural Computational Biology Programme, Spanish National Cancer Research Centre, E-28029 Madrid, Spain
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Kurkela M, Patana AS, Mackenzie PI, Court MH, Tate CG, Hirvonen J, Goldman A, Finel M. Interactions with other human UDP-glucuronosyltransferases attenuate the consequences of the Y485D mutation on the activity and substrate affinity of UGT1A6. Pharmacogenet Genomics 2007; 17:115-26. [PMID: 17301691 DOI: 10.1097/fpc.0b013e328011b598] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES To explore the possible role of hetero-oligomerization among the human UDP-glucuronosyltransferases in attenuating the consequences of the pathological Y486D mutation (UGT1A1 numbering) that often causes hyperbilirubinaemia. Owing to exon sharing in the human UGT1A gene, the equivalent mutation is present in all other UGT1As of the affected individuals. It is unknown, however, if this mutation results in clinical conditions, other than impaired bilirubin conjugation by UGT1A1. METHODS The main experimental approach in this study was to try and form hetero-oligomers of selected UDP-glucuronosyltransferases by coinfecting insect cells with recombinant baculoviruses that encode different human UDP-glucuronosyltransferases and mutants thereof. The infected cells were analysed for both relative expression levels and catalytic activity in each case, the combination of which yielded normalized activity. Kinetic analyses and copurification by affinity chromatography were also performed. RESULTS Coinfections with UGT1A4 increased the normalized scopoletin glucuronidation of 6YD (the Y485D mutant of UGT1A6) much more than it affected 1YD (the Y486D mutant of UGT1A1). Serotonin glucuronidation analyses revealed that coexpression of 6YD with most other human UDP-glucuronosyltransferases significantly increased the normalized activity of this mutant. Using 1-naphthol as the aglycone substrate, the Km of 6YD for the cosubstrate UDP-glucuronic acid was about 50 times higher than in UGT1A6. Yet, coexpression of 6YD with UGT1A4 lowered the Km for UDP-glucuronic acid to the level of UGT1A6. Coexpression also influenced wild-type UGT1A6 and UGT2B7, increasing the normalized activity of UGT1A6, but decreasing it for UGT2B7. CONCLUSION Hetero-oligomerization may play an important role in UDP-glucuronosyltransferases activity.
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Affiliation(s)
- Mika Kurkela
- Drug Discovery and Development Technology Center (DDTC) and Division of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
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14
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Kurkela M, Hirvonen J, Kostiainen R, Finel M. The interactions between the N-terminal and C-terminal domains of the human UDP-glucuronosyltransferases are partly isoform-specific, and may involve both monomers. Biochem Pharmacol 2004; 68:2443-50. [PMID: 15548391 DOI: 10.1016/j.bcp.2004.08.019] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2004] [Accepted: 08/09/2004] [Indexed: 11/16/2022]
Abstract
The pathological mutation Y486D was previously shown to reduce the activities of the UDP-glucuronosyltransferases (UGTs) 1A1 and 1A6 by about 88% and 99%, respectively. Surprisingly, the corresponding mutation in UGT1A9 (Y483D) doubled the Vmax of scopoletin glucuronidation, whereas the entacapone glucuronidation rate was decreased by about 50%. Due to the primary structure identity of the C-terminal half of all the human UGTs of the 1A subfamily, the sharp differences between them in the effect of a mutation deep inside the C-terminal half suggested that there are isoform-specific interactions between the variable N- and the conserved C-terminal halves. In dimeric enzymes, like the UGTs, such interactions might either occur within the same polypeptide, or between opposite monomers. The latter implies functional monomer-monomer interactions, and this was investigated using hetero-dimeric UGTs. Insect cells were co-infected with mixtures containing different combinations of recombinant baculoviruses encoding either UGT1A4 or 1A9Sol. The UGT1A4 was selected because it glucuronidates neither entacapone nor scopoletin at significant rates. The active enzyme in these hetero-dimers was 1A9Sol, a truncation mutant of UGT1A9 that exhibited a very low ratio of entacapone to scopoletin glucuronidation rates. Interestingly, the ratio of entacapone to scopoletin glucuronidation rates in the co-infected cells was dependent on, and markedly increased with, the probability that 1A9Sol forms hetero-dimers with UGT1A4. In addition, the apparent Km for entacapone in the hetero-dimers was much lower than in 1A9Sol, and resembled the corresponding value in full-length UGT1A9. The results, thus, revealed important monomer-monomer interactions within the UGTs.
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Affiliation(s)
- Mika Kurkela
- Viikki DDTC, University of Helsinki, P.O. Box 56 (Viikinkaari 5E), 00014 Helsinki, Finland
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