1
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Reed JR, Guidry JJ, Eyer M, Backes WL. The Influence of Lipid Microdomain Heterogeneity on Protein-Protein Interactions: Proteomic Analysis of Co-Immunoprecipitated Binding Partners of P450 1A2 and P450 3A in Rat Liver Microsomes. Drug Metab Dispos 2023; 51:1196-1206. [PMID: 37349115 PMCID: PMC10449098 DOI: 10.1124/dmd.123.001287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 06/02/2023] [Accepted: 06/07/2023] [Indexed: 06/24/2023] Open
Abstract
Liver cytochrome P450s (CYPs) of the endoplasmic reticulum (ER) are involved in the metabolism of exogenous and endogenous chemicals. The ER is not uniform, but possesses ordered lipid microdomains containing higher levels of saturated fatty acids, sphingomyelin, and cholesterol and disordered regions containing higher levels of polyunsaturated fatty acid chains. The various forms of drug-metabolizing P450s partition to either the ordered or disordered lipid microdomains with different degrees of specificity. P450s readily form complexes with ER-resident proteins, including other forms of P450. This study aims to ascertain whether lipid microdomain localization influences protein-P450 interactions in rat liver microsomes. Thus, liver microsomes were co-immunoprecipitated with CYP1A2-specific and CYP3A-specific antibodies, and the co-immunoprecipitating proteins were identified by liquid chromatography mass spectrometry proteomic analysis. These two P450s preferentially partition to ordered and disordered microdomains, respectively. More than 100 proteins were co-immunoprecipitated with each P450. Segregation of proteins into different microdomains did not preclude their interaction. However, CYP3A interacted broadly with proteins from ordered microdomains, whereas CYP1A2 reacted with a limited subset of these proteins. This is consistent with the concept of lipid raft heterogeneity and may indicate that CYP1A2 is targeted to a specific type of lipid raft. Although many of the interacting proteins for both P450s were other-drug metabolizing enzymes, other interactions were also evident. The consistent CYP3A binding partners were predominantly involved in phase I/II drug metabolism; however, CYP1A2 interacted not only with xenobiotic metabolizing enzymes, but also with enzymes involved in diverse cellular responses such as ER stress and protein folding. SIGNIFICANCE STATEMENT: This work describes the protein interactomes in rat liver microsomes of two important cytochromes P450s (CYP1A2 and CYP3A) in drug metabolism and describes the relationship of the interacting proteins to lipid microdomain distribution.
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Affiliation(s)
- James R Reed
- Department of Pharmacology and Experimental Therapeutics and The Stanley S. Scott Cancer Center, Louisiana State University Health Science Center, New Orleans, Louisiana
| | - Jessie J Guidry
- Department of Pharmacology and Experimental Therapeutics and The Stanley S. Scott Cancer Center, Louisiana State University Health Science Center, New Orleans, Louisiana
| | - Marilyn Eyer
- Department of Pharmacology and Experimental Therapeutics and The Stanley S. Scott Cancer Center, Louisiana State University Health Science Center, New Orleans, Louisiana
| | - Wayne L Backes
- Department of Pharmacology and Experimental Therapeutics and The Stanley S. Scott Cancer Center, Louisiana State University Health Science Center, New Orleans, Louisiana
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2
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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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3
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Dangi B, Davydova NY, Maldonado MA, Ahire D, Prasad B, Davydov DR. Probing functional interactions between cytochromes P450 with principal component analysis of substrate saturation profiles and targeted proteomics. Arch Biochem Biophys 2021; 708:108937. [PMID: 34058150 PMCID: PMC8260145 DOI: 10.1016/j.abb.2021.108937] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 05/01/2021] [Accepted: 05/21/2021] [Indexed: 11/28/2022]
Abstract
We investigated the correspondence between drug metabolism routes and the composition of the P450 ensemble in human liver microsomes (HLM). As a probe, we used Coumarin 152 (C152), a fluorogenic substrate metabolized by multiple P450 species. Studying the substrate-saturation profiles (SSP) in seven pooled HLM preparations, we sought to correlate them with the P450 pool's composition characterized by targeted proteomics. This analysis, complemented with the assays with specific inhibitors of CYP3A4 and CYP2C19, the primary C152 metabolizers, demonstrated a significant contrast between different HLM samples. To unveil the source of these differences, we implemented Principal Component Analysis (PCA) of the SSP series obtained with HLM samples with a known composition of the P450 pool. Our analysis revealed that the parameters of C152 metabolism are primarily determined by the content of CYP2A6, CYP2B6, CYP2C8, CYP2E1, and CYP3A5 of those only CYP2B6 and CYP3A5 can metabolize C152. To validate this finding, we studied the effect of enriching HLM with CYP2A6, CYP2E1, and CYP3A5. The incorporation of CYP3A5 into HLM decreases the rate of C152 metabolism while increasing the role of CYP2B6 in its turnover. In contrast, incorporation of CYP2A6 and CYP2E1 reroutes the C152 demethylation towards some P450 enzyme with a moderate affinity to the substrate, most likely CYP3A4. Our results reveal a sharp non-additivity of the individual P450 properties and suggest a pivotal role of P450-P450 interactions in determining drug metabolism routes. This study demonstrates the high potential of our new PCA-based approach in unveiling functional interrelationships between different P450 species.
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Affiliation(s)
- Bikash Dangi
- Department of Chemistry, Washington State University, Pullman, WA, 99164, USA
| | - Nadezhda Y Davydova
- Department of Chemistry, Washington State University, Pullman, WA, 99164, USA
| | - Marc A Maldonado
- Department of Chemistry, Washington State University, Pullman, WA, 99164, USA
| | - Deepak Ahire
- Department of Pharmaceutical Sciences, Washington State University, Spokane, WA, 99202, USA
| | - Bhagwat Prasad
- Department of Pharmaceutical Sciences, Washington State University, Spokane, WA, 99202, USA
| | - Dmitri R Davydov
- Department of Chemistry, Washington State University, Pullman, WA, 99164, USA.
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4
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Identification of the contact region responsible for the formation of the homomeric CYP1A2•CYP1A2 complex. Biochem J 2021; 478:2163-2178. [PMID: 34032264 DOI: 10.1042/bcj20210269] [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: 04/19/2021] [Revised: 05/21/2021] [Accepted: 05/25/2021] [Indexed: 11/17/2022]
Abstract
Previous studies showed that cytochrome P450 1A2 (CYP1A2) forms a homomeric complex that influences its metabolic characteristics. Specifically, CYP1A2 activity exhibits a sigmoidal response as a function of NADPH-cytochrome P450 reductase (POR) concentration and is consistent with an inhibitory CYP1A2•CYP1A2 complex that is disrupted by increasing [POR] (Reed et al. (2012) Biochem. J. 446, 489-497). The goal of this study was to identify the CYP1A2 contact regions involved in homomeric complex formation. Examination of X-ray structure of CYP1A2 implicated the proximal face in homomeric complex formation. Consequently, the involvement of residues L91-K106 (P1 region) located on the proximal face of CYP1A2 was investigated. This region was replaced with the homologous region of CYP2B4 (T81-S96) and the protein was expressed in HEK293T/17 cells. Complex formation and its disruption was observed using bioluminescence resonance energy transfer (BRET). The P1-CYP1A2 (CYP1A2 with the modified P1 region) exhibited a decreased BRET signal as compared with wild-type CYP1A2 (WT-CYP1A2). On further examination, P1-CYP1A2 was much less effective at disrupting the CYP1A2•CYP1A2 homomeric complex, when compared with WT-CYP1A2, thereby demonstrating impaired binding of P1-CYP1A2 to WT-CYP1A2 protein. In contrast, the P1 substitution did not affect its ability to form a heteromeric complex with CYP2B4. P1-CYP1A2 also showed decreased activity as compared with WT-CYP1A2, which was consistent with a decrease in the ability of P1-CYP1A2 to associate with WT-POR, again implicating the P1 region in POR binding. These results indicate that the contact region responsible for the CYP1A2•CYP1A2 homomeric complex resides in the proximal region of the protein.
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5
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Fujimoto K, Takeuchi H, Takaku T, Abe J, Harada K. Designing a novel photoinduced electron transfer-based small-molecule fluorescent probe specific for CYP3A isozymes. Bioorg Med Chem Lett 2021; 47:128195. [PMID: 34119614 DOI: 10.1016/j.bmcl.2021.128195] [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: 01/21/2021] [Revised: 06/01/2021] [Accepted: 06/06/2021] [Indexed: 10/21/2022]
Abstract
Cytochrome P450 (CYPs) are oxidoreductases distributed in various tissues in plants and animals. Among the CYP families, CYP3A is the most abundant in vivo, particularly in humans, and it is involved in the metabolism of many drugs. It is crucial to measure CYP3A activity for both pharmaceuticals and agrochemicals because inhibition or induction of this enzyme can seriously affect the occurrence of toxicity or efficacy. In the present study, a novel fluorescent probe, 6-(2,5-bis(trifluoromethyl)benzyloxy)-9-(4-methoxy-2-methylphenyl)-3H-xanthen-3-one (BMX, quantum efficiency: 21%), was designed and synthesized. The design was done by photoinduced electron transfer strategy. BMX was specifically metabolized only using CYP3A to generate 2-Me-4-MeO TokyoGreen (quantum efficiency: 85%), resulting in strong fluorescence in the presence of CYP3A isozymes. Protein assays using recombinant human, rat, and mouse CYP isozymes demonstrated the selective metabolism of BMX and production of fluorescence only by CYP3A in all species.
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Affiliation(s)
- Keiichi Fujimoto
- Environmental Health Science Laboratory, Sumitomo Chemical Co., Ltd, 1-98, Kasugade-Naka 3-Chome, Konohana-Ku, Osaka 554-8558, Japan.
| | - Hayato Takeuchi
- Environmental Health Science Laboratory, Sumitomo Chemical Co., Ltd, 1-98, Kasugade-Naka 3-Chome, Konohana-Ku, Osaka 554-8558, Japan.
| | - Tomoyuki Takaku
- Corporate Planning Office, Sumitomo Chemical Co., Ltd, 27-1, Shinkawa 2-chome Chuo-Ku, Tokyo 104-8260, Japan.
| | - Jun Abe
- Environmental Health Science Laboratory, Sumitomo Chemical Co., Ltd, 1-98, Kasugade-Naka 3-Chome, Konohana-Ku, Osaka 554-8558, Japan.
| | - Koichiro Harada
- Intellectual Property Departure, Sumitomo Chemical Co., Ltd, 5-33, Kitahama 4-chome, Chuo-Ku, Osaka 541-8550, Japan.
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6
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Regioselective Hydroxylation of Phloretin, a Bioactive Compound from Apples, by Human Cytochrome P450 Enzymes. Pharmaceuticals (Basel) 2020; 13:ph13110330. [PMID: 33105851 PMCID: PMC7690628 DOI: 10.3390/ph13110330] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 10/17/2020] [Accepted: 10/21/2020] [Indexed: 01/15/2023] Open
Abstract
Phloretin, the major polyphenol compound in apples and apple products, is interesting because it shows beneficial effects on human health. It is mainly found as a form of glucoside, phlorizin. However, the metabolic pathway of phloretin in humans has not been reported. Therefore, identifying phloretin metabolites made in human liver microsomes and the human cytochrome P450 (P450) enzymes to make them is interesting. In this study, the roles of human liver P450s for phloretin oxidation were examined using human liver microsomes and recombinant human liver P450s. One major metabolite of phloretin in human liver microsomes was 3-OH phloretin, which is the same product of a bacterial CYP102A1-catalyzed reaction of phloretin. CYP3A4 and CYP2C19 showed kcat values of 3.1 and 5.8 min-1, respectively. However, CYP3A4 has a 3.3-fold lower Km value than CYP2C19. The catalytic efficiency of a CYP3A4-catalyzed reaction is 1.8-fold higher than a reaction catalyzed by CYP2C19. Whole-cell biotransformation with CYP3A4 was achieved 0.16 mM h-1 productivity for 3-OH phlorein from 8 mM phloretin at optimal condition. Phloretin was a potent inhibitor of CYP3A4-catalyzed testosterone 6β-hydroxylation activity. Antibodies against CYP3A4 inhibited up to 90% of the microsomal activity of phloretin 3-hydroxylation. The immunoinhibition effect of anti-2C19 is much lower than that of anti-CYP3A4. Thus, CYP3A4 majorly contributes to the human liver microsomal phloretin 3-hydroxylation, and CYP2C19 has a minor role.
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7
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Huff HC, Maroutsos D, Das A. Lipid composition and macromolecular crowding effects on CYP2J2-mediated drug metabolism in nanodiscs. Protein Sci 2019; 28:928-940. [PMID: 30861250 DOI: 10.1002/pro.3603] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 03/11/2019] [Indexed: 01/13/2023]
Abstract
Lipid composition and macromolecular crowding are key external effectors of protein activity and stability whose role varies between different proteins. Therefore, it is imperative to study their effects on individual protein function. CYP2J2 is a membrane-bound cytochrome P450 in the heart involved in the metabolism of fatty acids and xenobiotics. In order to facilitate this metabolism, cytochrome P450 reductase (CPR), transfers electrons to CYP2J2 from NADPH. Herein, we use nanodiscs to show that lipid composition of the membrane bilayer affects substrate metabolism of the CYP2J2-CPR nanodisc (ND) system. Differential effects on both NADPH oxidation and substrate metabolism by CYP2J2-CPR are dependent on the lipid composition. For instance, sphingomyelin containing nanodiscs produced more secondary substrate metabolites than discs of other lipid compositions, implying a possible conformational change leading to processive metabolism. Furthermore, we demonstrate that macromolecular crowding plays a role in the lipid-solubilized CYP2J2-CPR system by increasing the Km and decreasing the Vmax , and effect that is size-dependent. Crowding also affects the CYP2J2-CPR-ND system by decreasing both the Km and Vmax for Dextran-based macromolecular crowding agents, implying an increase in substrate affinity but a lack of metabolism. Finally, protein denaturation studies show that crowding agents destabilize CYP2J2, while the multidomain protein CPR is stabilized. Overall, these studies are the first report on the role of the surrounding lipid environment and macromolecular crowding in modulating enzymatic function of CYP2J2-CPR membrane protein system.
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Affiliation(s)
- Hannah C Huff
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Demetri Maroutsos
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Aditi Das
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801.,Beckman Institute for Advanced Science and Technology, Division of Nutritional Science, Neuroscience Program, and Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801.,Department of Comparative Biosciences, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
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8
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Sagwan-Barkdoll L, Anterola AM. Taxadiene-5α-ol is a minor product of CYP725A4 when expressed in Escherichia coli. Biotechnol Appl Biochem 2018; 65:294-305. [PMID: 28876471 PMCID: PMC5839926 DOI: 10.1002/bab.1606] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 09/02/2017] [Indexed: 11/11/2022]
Abstract
CYP725A4 is a P450 enzyme from Taxus cuspidata that catalyzes the formation of taxadiene-5α-ol (T5α-ol) from taxadiene in paclitaxel biosynthesis. Past attempts expressing CYP725A4 in heterologous hosts reported the formation of 5(12)-oxa-3(11)-cyclotaxane (OCT) and/or 5(11)-oxa-3(11)-cyclotaxane (iso-OCT) instead of, or in addition to, T5α-ol. Here, we report that T5α-ol is produced as a minor product by Escherichia coli expressing both taxadiene synthase and CYP725A4. The major products were OCT and iso-OCT, while trace amounts of unidentified monooxygenated taxanes were also detected by gas chromatography-mass spectrometry. Since OCT and iso-OCT had not been found in nature, we tested the hypothesis that protein-protein interaction of CYP725A4 with redox partners, such as cytochrome P450 reductase (CPR) and cytochrome b5, may affect the products formed by CYP725A4, possibly favoring the formation of T5α-ol over OCT and iso-OCT. Our results show that coexpression of CYP725A4 with CPR from different organisms did not change the relative ratios of OCT, iso-OCT, and T5α-ol, while cytochrome b5 decreased overall levels of the products formed. Although unsuccessful in finding conditions that promote T5α-ol formation over other products, we used our results to clarify conflicting claims in the literature and discuss other possible approaches to produce paclitaxel via metabolic and enzyme engineering.
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Affiliation(s)
- Laxmi Sagwan-Barkdoll
- Department of Plant Biology, Southern Illinois University, Carbondale, IL 62901, USA
| | - Aldwin M. Anterola
- Department of Plant Biology, Southern Illinois University, Carbondale, IL 62901, USA
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9
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Bart AG, Scott EE. Structural and functional effects of cytochrome b5 interactions with human cytochrome P450 enzymes. J Biol Chem 2017; 292:20818-20833. [PMID: 29079577 DOI: 10.1074/jbc.ra117.000220] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Revised: 10/22/2017] [Indexed: 02/04/2023] Open
Abstract
The small heme-containing protein cytochrome b5 can facilitate, inhibit, or have no effect on cytochrome P450 catalysis, often in a P450-dependent and substrate-dependent manner that is not well understood. Herein, solution NMR was used to identify b5 residues interacting with different human drug-metabolizing P450 enzymes. NMR results revealed that P450 enzymes bound to either b5 α4-5 (CYP2A6 and CYP2E1) or this region and α2-3 (CYP2D6 and CYP3A4) and suggested variation in the affinity for b5 Mutations of key b5 residues suggest not only that different b5 surfaces are responsible for binding different P450 enzymes, but that these different complexes are relevant to the observed effects on P450 catalysis.
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Affiliation(s)
| | - Emily E Scott
- From the Biophysics Program and .,the Departments of Medicinal Chemistry and Pharmacology, University of Michigan, Ann Arbor, Michigan 48109
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10
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Reed JR, Backes WL. The functional effects of physical interactions involving cytochromes P450: putative mechanisms of action and the extent of these effects in biological membranes. Drug Metab Rev 2017; 48:453-69. [PMID: 27500687 DOI: 10.1080/03602532.2016.1221961] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Cytochromes P450 represent a family of enzymes, which are responsible for the oxidative metabolism of a wide variety of xenobiotics. Although the mammalian P450s require interactions with their redox partners in order to function, more recently, P450 system proteins have been shown to exist as multi-protein complexes that include the formation of P450•P450 complexes. Evidence has shown that the metabolism of some substrates by a given P450 can be influenced by the specific interaction of the enzyme with other forms of P450. Detailed kinetic analysis of these reactions in vitro has shown that the P450-P450 interactions can alter metabolism by changing the ability of a P450 to bind to its cognate redox partner, NADPH-cytochrome P450 reductase; by altering substrate binding to the affected P450; and/or by changing the rate of a catalytic step of the reaction cycle. This review summarizes the known examples of P450-P450 interactions that have been shown in vitro to influence metabolism and categorizes them according to the mechanism(s) causing the effects. P450-P450 interactions have the potential to cause major changes in the metabolism and elimination of drugs in vivo. This review summarizes the evidence that the P450-P450 interactions influence metabolism in biological membranes and discusses the studies, which will provide further insight into the extent of these effects in the future.
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Affiliation(s)
- James R Reed
- a Department of Pharmacology and Experimental Therapeutics, and The Stanley S. Scott Cancer Center , Louisiana State University Health Sciences Center , New Orleans , LA , USA
| | - Wayne L Backes
- a Department of Pharmacology and Experimental Therapeutics, and The Stanley S. Scott Cancer Center , Louisiana State University Health Sciences Center , New Orleans , LA , USA
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11
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Albertolle ME, Kim D, Nagy LD, Yun CH, Pozzi A, Savas Ü, Johnson EF, Guengerich FP. Heme-thiolate sulfenylation of human cytochrome P450 4A11 functions as a redox switch for catalytic inhibition. J Biol Chem 2017; 292:11230-11242. [PMID: 28533430 DOI: 10.1074/jbc.m117.792200] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 05/16/2017] [Indexed: 11/06/2022] Open
Abstract
Cytochrome P450 (P450, CYP) 4A11 is a human fatty acid ω-hydroxylase that catalyzes the oxidation of arachidonic acid to the eicosanoid 20-hydroxyeicosatetraenoic acid (20-HETE), which plays important roles in regulating blood pressure regulation. Variants of P450 4A11 have been associated with high blood pressure and resistance to anti-hypertensive drugs, and 20-HETE has both pro- and antihypertensive properties relating to increased vasoconstriction and natriuresis, respectively. These physiological activities are likely influenced by the redox environment, but the mechanisms are unclear. Here, we found that reducing agents (e.g. dithiothreitol and tris(2-carboxyethyl)phosphine) strongly enhanced the catalytic activity of P450 4A11, but not of 10 other human P450s tested. Conversely, added H2O2 attenuated P450 4A11 catalytic activity. Catalytic roles of five of the potentially eight implicated Cys residues of P450 4A11 were eliminated by site-directed mutagenesis. Using an isotope-coded dimedone/iododimedone-labeling strategy and mass spectrometry of peptides, we demonstrated that the heme-thiolate cysteine (Cys-457) is selectively sulfenylated in an H2O2 concentration-dependent manner. This sulfenylation could be reversed by reducing agents, including dithiothreitol and dithionite. Of note, we observed heme ligand cysteine sulfenylation of P450 4A11 ex vivo in kidneys and livers derived from CYP4A11 transgenic mice. We also detected sulfenylation of murine P450 4a12 and 4b1 heme peptides in kidneys. To our knowledge, reversible oxidation of the heme thiolate has not previously been observed in P450s and may have relevance for 20-HETE-mediated functions.
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Affiliation(s)
- Matthew E Albertolle
- From the Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146
| | - Donghak Kim
- From the Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146.,the Department of Biological Sciences, Konkuk University, Seoul 05025, Korea
| | - Leslie D Nagy
- From the Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146
| | - Chul-Ho Yun
- the School of Biological Sciences and Technology, Chonnam National University, Gwangju 61186, Korea
| | - Ambra Pozzi
- the Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37232-6602.,the Veterans Affairs Medical Center, Nashville, Tennessee 37232, and
| | - Üzen Savas
- the Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California 92037
| | - Eric F Johnson
- the Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California 92037
| | - F Peter Guengerich
- From the Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146,
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12
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Abstract
Membrane proteins play a most important part in metabolism, signaling, cell motility, transport, development, and many other biochemical and biophysical processes which constitute fundamentals of life on the molecular level. Detailed understanding of these processes is necessary for the progress of life sciences and biomedical applications. Nanodiscs provide a new and powerful tool for a broad spectrum of biochemical and biophysical studies of membrane proteins and are commonly acknowledged as an optimal membrane mimetic system that provides control over size, composition, and specific functional modifications on the nanometer scale. In this review we attempted to combine a comprehensive list of various applications of nanodisc technology with systematic analysis of the most attractive features of this system and advantages provided by nanodiscs for structural and mechanistic studies of membrane proteins.
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Affiliation(s)
- Ilia G Denisov
- Department of Biochemistry and Department of Chemistry, University of Illinois , Urbana, Illinois 61801, United States
| | - Stephen G Sligar
- Department of Biochemistry and Department of Chemistry, University of Illinois , Urbana, Illinois 61801, United States
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13
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Shimada T, Takenaka S, Murayama N, Yamazaki H, Kim JH, Kim D, Yoshimoto FK, Guengerich FP, Komori M. Oxidation of Acenaphthene and Acenaphthylene by Human Cytochrome P450 Enzymes. Chem Res Toxicol 2016; 28:268-78. [PMID: 25642975 DOI: 10.1021/tx500505y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Acenaphthene and acenaphthylene, two known environmental polycyclic aromatic hydrocarbon (PAH)pollutants, were incubated at 50 μM concentrations in a standard reaction mixture with human P450s 2A6, 2A13, 1B1,1A2, 2C9, and 3A4, and the oxidation products were determined using HPLC and LC-MS. HPLC analysis showed that P450 2A6 converted acenaphthene and acenaphthylene to several mono- and dioxygenated products. LC-MS analysis of acenaphthene oxidation by P450s indicated the formation of1-acenaphthenol as a major product, with turnover rates of 6.7,4.5, and 3.6 nmol product formed/min/nmol P450 for P4502A6, 2A13, and 1B1, respectively. Acenaphthylene oxidation by P450 2A6 showed the formation of 1,2-epoxyacenaphthene as a major product (4.4 nmol epoxide formed/min/nmol P450) and also several mono- and dioxygenated products.P450 2A13, 1B1, 1A2, 2C9, and 3A4 formed 1,2-epoxyacenaphthene at rates of 0.18, 5.3 2.4, 0.16, and 3.8 nmol/min/nmol P450, respectively. 1-Acenaphthenol, which induced Type I binding spectra with P450 2A13, was further oxidized by P450 2A13 but not P450 2A6. 1,2-Epoxyacenaphthene induced Type I binding spectra with P450 2A6 and 2A13 (K(s) 1.8 and 0.16 μM,respectively) and was also oxidized to several oxidation products by these P450s. Molecular docking analysis suggested different orientations of acenaphthene, acenaphthylene, 1-acenaphthenol, and 1,2-epoxyacenaphthene in their interactions with P450 2A6a nd 2A13. Neither of these four PAHs induced umu gene expression in a Salmonella typhimurium NM tester strain. These results suggest, for the first time, that acenaphthene and acenaphthylene are oxidized by human P450s 2A6 and 2A13 and other P450s to form several mono- and dioxygenated products. The results are of use in considering the biological and toxicological significance of these environmental PAHs in humans.
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15
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Characterization of cytochrome P450 isoforms involved in sequential two-step bioactivation of diclofenac to reactive p-benzoquinone imines. Toxicol Lett 2016; 253:46-54. [PMID: 27130197 DOI: 10.1016/j.toxlet.2016.04.022] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 04/08/2016] [Accepted: 04/22/2016] [Indexed: 11/23/2022]
Abstract
Idiosyncratic drug-induced lever injury (IDILI) is a rare but severe side effect of diclofenac (DF). Several mechanisms have been proposed as cause of DF-induced toxicity including the formation of protein-reactive diclofenac-1',4'-quinone imine (DF-1',4'-QI) and diclofenac-2,5-quinone imine (DF-2,5-QI). Formation of these p-benzoquinone imines result from two-step oxidative metabolism involving aromatic hydroxylation to 4'-hydroxydiclofenac and 5-hydroxydiclofenac followed by dehydrogenation to DF-1',4'-QI and DF-2,5-QI, respectively. Although the contribution of individual cytochrome P450s (CYPs) in aromatic hydroxylation of DF is well studied, the enzymes involved in the dehydrogenation reactions have been poorly characterized. The results of the present study show that both formation of 4'-hydroxydiclofenac and it subsequent bioactivation to DF-1',4'-QI is selectively catalyzed by CYP2C9. However, the two-step bioactivation to DF-2,5-QI appears to be catalyzed with highest activity by two different CYPs: 5-hydroxylation of DF is predominantly catalyzed by CYP3A4, whereas its subsequent bioactivation to DF-2,5-QI is catalyzed with 14-fold higher intrinsic clearance by CYP2C9. The fact that both CYPs involved in two-step bioactivation of DF show large interindividual variability may play a role in different susceptibility of patients to DF-induced IDILI. Furthermore, expression levels of these enzymes and protective enzymes might be important factors determining sensitivity of in vitro models for hepatotoxicity.
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Davydov DR. Molecular organization of the microsomal oxidative system: a new connotation for an old term. BIOCHEMISTRY MOSCOW-SUPPLEMENT SERIES B-BIOMEDICAL CHEMISTRY 2016. [DOI: 10.1134/s1990750816010042] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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17
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Bostick CD, Hickey KM, Wollenberg LA, Flora DR, Tracy TS, Gannett PM. Immobilized Cytochrome P450 for Monitoring of P450-P450 Interactions and Metabolism. ACTA ACUST UNITED AC 2016; 44:741-9. [PMID: 26961240 DOI: 10.1124/dmd.115.067637] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 03/09/2016] [Indexed: 11/22/2022]
Abstract
Cytochrome P450 (P450) protein-protein interactions have been shown to alter their catalytic activity. Furthermore, these interactions are isoform specific and can elicit activation, inhibition, or no effect on enzymatic activity. Studies show that these effects are also dependent on the protein partner cytochrome P450 reductase (CPR) and the order of protein addition to purified reconstituted enzyme systems. In this study, we use controlled immobilization of P450s to a gold surface to gain a better understanding of P450-P450 interactions between three key drug-metabolizing isoforms (CYP2C9, CYP3A4, and CYP2D6). Molecular modeling was used to assess the favorability of homomeric/heteromeric P450 complex formation. P450 complex formation in vitro was analyzed in real time utilizing surface plasmon resonance. Finally, the effects of P450 complex formation were investigated utilizing our immobilized platform and reconstituted enzyme systems. Molecular modeling shows favorable binding of CYP2C9-CPR, CYP2C9-CYP2D6, CYP2C9-CYP2C9, and CYP2C9-CYP3A4, in rank order.KDvalues obtained via surface plasmon resonance show strong binding, in the nanomolar range, for the above pairs, with CYP2C9-CYP2D6 yielding the lowestKD, followed by CYP2C9-CYP2C9, CYP2C9-CPR, and CYP2C9-CYP3A4. Metabolic incubations show that immobilized CYP2C9 metabolism was activated by homomeric complex formation. CYP2C9 metabolism was not affected by the presence of CYP3A4 with saturating CPR concentrations. CYP2C9 metabolism was activated by CYP2D6 at saturating CPR concentrations in solution but was inhibited when CYP2C9 was immobilized. The order of addition of proteins (CYP2C9, CYP2D6, CYP3A4, and CPR) influenced the magnitude of inhibition for CYP3A4 and CYP2D6. These results indicate isoform-specific P450 interactions and effects on P450-mediated metabolism.
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Affiliation(s)
- Chris D Bostick
- Department of Pharmaceutical Sciences, School of Pharmacy, West Virginia University, Morgantown, West Virginia (C.D.B., K.M.H.); Array BioPharma, Boulder, Colorado (L.A.W.); Department of Experimental and Clinical Pharmacology, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota (D.R.F.); College of Pharmacy, University of Kentucky, Lexington, Kentucky (T.S.T.); and Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Ft. Lauderdale, Florida (P.M.G.)
| | - Katherine M Hickey
- Department of Pharmaceutical Sciences, School of Pharmacy, West Virginia University, Morgantown, West Virginia (C.D.B., K.M.H.); Array BioPharma, Boulder, Colorado (L.A.W.); Department of Experimental and Clinical Pharmacology, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota (D.R.F.); College of Pharmacy, University of Kentucky, Lexington, Kentucky (T.S.T.); and Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Ft. Lauderdale, Florida (P.M.G.)
| | - Lance A Wollenberg
- Department of Pharmaceutical Sciences, School of Pharmacy, West Virginia University, Morgantown, West Virginia (C.D.B., K.M.H.); Array BioPharma, Boulder, Colorado (L.A.W.); Department of Experimental and Clinical Pharmacology, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota (D.R.F.); College of Pharmacy, University of Kentucky, Lexington, Kentucky (T.S.T.); and Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Ft. Lauderdale, Florida (P.M.G.)
| | - Darcy R Flora
- Department of Pharmaceutical Sciences, School of Pharmacy, West Virginia University, Morgantown, West Virginia (C.D.B., K.M.H.); Array BioPharma, Boulder, Colorado (L.A.W.); Department of Experimental and Clinical Pharmacology, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota (D.R.F.); College of Pharmacy, University of Kentucky, Lexington, Kentucky (T.S.T.); and Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Ft. Lauderdale, Florida (P.M.G.)
| | - Timothy S Tracy
- Department of Pharmaceutical Sciences, School of Pharmacy, West Virginia University, Morgantown, West Virginia (C.D.B., K.M.H.); Array BioPharma, Boulder, Colorado (L.A.W.); Department of Experimental and Clinical Pharmacology, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota (D.R.F.); College of Pharmacy, University of Kentucky, Lexington, Kentucky (T.S.T.); and Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Ft. Lauderdale, Florida (P.M.G.)
| | - Peter M Gannett
- Department of Pharmaceutical Sciences, School of Pharmacy, West Virginia University, Morgantown, West Virginia (C.D.B., K.M.H.); Array BioPharma, Boulder, Colorado (L.A.W.); Department of Experimental and Clinical Pharmacology, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota (D.R.F.); College of Pharmacy, University of Kentucky, Lexington, Kentucky (T.S.T.); and Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Ft. Lauderdale, Florida (P.M.G.)
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Davydov DR. [Molecular organization of the microsomal oxidative system: a new connotation for an old term]. BIOMEDIT︠S︡INSKAI︠A︡ KHIMII︠A︡ 2015; 61:176-87. [PMID: 25978385 DOI: 10.18097/pbmc20156102176] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The central role that cytochromes P450 play in the metabolism of drugs and other xenobiotics makes these enzymes a major subject for studies of drug disposition, adverse drug effects and drug-drug interactions. Although there has been tremendous success in delineating P450 mechanisms, the concept of the drug-metabolizing ensemble as a functionally integrated system remains undeveloped. However, eukaryotic cells typically possess a multitude of different P450 enzymes that are co-localized in the membrane of endoplasmic reticulum (ER) and interact with each other with the formation of dynamic heteromeric complexes (mixed oligomers). Appreciation of the importance of developing an integral, systems approach to the ensemble of cytochromes P450 as an integral system inspired growing interest of researchers to the molecular organization of microsomal monooxygenase, which remained in the focus of research of academician Archakov for over 40 years. Fundamental studies carried out under his guidance have an important impact on our current concepts in this area. Further exploration of the molecular organization of the system of microsomal monooxygenase as an integral multienzyme and multifunctional system will have an essential impact on our understanding of the key factors that determine the changes in human drug metabolism and other P450-related functions in development, aging, and disease, as well as under influence of drugs, food ingredients, and environmental contaminants.
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Affiliation(s)
- D R Davydov
- Institute of Biomedical Chemistry, Moscow, Russia; Department of Chemistry, Washington State University, Washington, USA
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Stiborová M, Bárta F, Levová K, Hodek P, Schmeiser HH, Arlt VM, Martínek V. A Mechanism of O-Demethylation of Aristolochic Acid I by Cytochromes P450 and Their Contributions to This Reaction in Human and Rat Livers: Experimental and Theoretical Approaches. Int J Mol Sci 2015; 16:27561-75. [PMID: 26593908 PMCID: PMC4661905 DOI: 10.3390/ijms161126047] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 10/30/2015] [Accepted: 11/05/2015] [Indexed: 01/30/2023] Open
Abstract
Aristolochic acid I (AAI) is a plant alkaloid causing aristolochic acid nephropathy, Balkan endemic nephropathy and their associated urothelial malignancies. AAI is detoxified by cytochrome P450 (CYP)-mediated O-demethylation to 8-hydroxyaristolochic acid I (aristolochic acid Ia, AAIa). We previously investigated the efficiencies of human and rat CYPs in the presence of two other components of the mixed-functions-oxidase system, NADPH:CYP oxidoreductase and cytochrome b₅, to oxidize AAI. Human and rat CYP1A are the major enzymes oxidizing AAI. Other CYPs such as CYP2C, 3A4, 2D6, 2E1, and 1B1, also form AAIa, but with much lower efficiency than CYP1A. Based on velocities of AAIa formation by examined CYPs and their expression levels in human and rat livers, here we determined the contributions of individual CYPs to AAI oxidation in these organs. Human CYP1A2 followed by CYP2C9, 3A4 and 1A1 were the major enzymes contributing to AAI oxidation in human liver, while CYP2C and 1A were most important in rat liver. We employed flexible in silico docking methods to explain the differences in AAI oxidation in the liver by human CYP1A1, 1A2, 2C9, and 3A4, the enzymes that all O-demethylate AAI, but with different effectiveness. We found that the binding orientations of the methoxy group of AAI in binding centers of the CYP enzymes and the energies of AAI binding to the CYP active sites dictate the efficiency of AAI oxidation. Our results indicate that utilization of experimental and theoretical methods is an appropriate study design to examine the CYP-catalyzed reaction mechanisms of AAI oxidation and contributions of human hepatic CYPs to this metabolism.
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Affiliation(s)
- Marie Stiborová
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, Prague 2 CZ-12843, Czech Republic.
| | - František Bárta
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, Prague 2 CZ-12843, Czech Republic.
| | - Kateřina Levová
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, Prague 2 CZ-12843, Czech Republic.
| | - Petr Hodek
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, Prague 2 CZ-12843, Czech Republic.
| | - Heinz H Schmeiser
- Division of Radiopharmaceutical Chemistry, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg 69120, Germany.
| | - Volker M Arlt
- Analytical and Environmental Sciences Division, MRC-PHE Centre for Environment and Health, King's College London, London SE1 9NH, UK.
| | - Václav Martínek
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, Prague 2 CZ-12843, Czech Republic.
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20
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Ječmen T, Ptáčková R, Černá V, Dračínská H, Hodek P, Stiborová M, Hudeček J, Šulc M. Photo-initiated crosslinking extends mapping of the protein-protein interface to membrane-embedded portions of cytochromes P450 2B4 and b₅. Methods 2015; 89:128-37. [PMID: 26235815 DOI: 10.1016/j.ymeth.2015.07.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Revised: 07/27/2015] [Accepted: 07/28/2015] [Indexed: 01/17/2023] Open
Abstract
Protein-protein interactions play a central role in the regulation of many biochemical processes (e.g. the system participating in enzyme catalysis). Therefore, a deeper understanding of protein-protein interactions may contribute to the elucidation of many biologically important mechanisms. For this purpose, it is necessary to establish the composition and stoichiometry of supramolecular complexes and to identify the crucial portions of the interacting molecules. This study is devoted to structure-functional relationships in the microsomal Mixed Function Oxidase (MFO) complex, which is responsible for biotransformation of many hydrophobic endogenous compounds and xenobiotics. In particular, the cytochrome b5 interaction with MFO terminal oxygenase cytochrome P-450 (P450) was studied. To create photolabile probes suitable for this purpose, we prepared cytochrome b5 which had a photolabile diazirine analog of methionine (pMet) incorporated into the protein sequence, employing recombinant expression in Escherichia coli. In addition to wild-type cytochrome b5, where three methionines (Met) are located at positions 96, 126, and 131, six mutants containing only one Met in the sequence were designed and expressed (see Table 1). In these mutants, a single Met was engineered into the catalytic domain (at positions 23, 41, or 46), into the linker between the protein domains (at position 96), or into the membrane region (at positions 126 or 131). These mutants should confirm or exclude these portions of cytochrome b5 which are involved in the interaction with P450. After UV irradiation, the pMet group(s) in the photolabile cytochrome b5 probe was(were) activated, producing covalent crosslinks with the interacting parts of P450 2B4 in the close vicinity. The covalent complexes were analyzed by the "bottom up" approach with high-accuracy mass spectrometry. The analysis provided an identification of the contacts in the supramolecular complex with low structural resolution. We found that all the above-mentioned cytochrome b5 Met residues can form intermolecular crosslinks and thus participate in the interaction. In addition, our results indicate the existence of at least two P450:cytochrome b5 complexes which differ in the orientation of individual proteins. The results demonstrate the advantages of the photo-initiated crosslinking technique which is able to map the protein-protein interfaces not only in the solvent exposed regions, but also in the membrane-embedded segments (compared to a typical crosslinking approach which generally only identifies crosslinks in solvent exposed regions).
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Affiliation(s)
- Tomáš Ječmen
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, CZ-12843 Prague 2, Czech Republic; Institute of Microbiology v.v.i., Academy of Sciences of the Czech Republic, Vídeňská 1083, CZ-14220 Prague 4, Czech Republic
| | - Renata Ptáčková
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, CZ-12843 Prague 2, Czech Republic; Institute of Microbiology v.v.i., Academy of Sciences of the Czech Republic, Vídeňská 1083, CZ-14220 Prague 4, Czech Republic
| | - Věra Černá
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, CZ-12843 Prague 2, Czech Republic
| | - Helena Dračínská
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, CZ-12843 Prague 2, Czech Republic
| | - Petr Hodek
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, CZ-12843 Prague 2, Czech Republic
| | - Marie Stiborová
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, CZ-12843 Prague 2, Czech Republic
| | - Jiří Hudeček
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, CZ-12843 Prague 2, Czech Republic
| | - Miroslav Šulc
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, CZ-12843 Prague 2, Czech Republic; Institute of Microbiology v.v.i., Academy of Sciences of the Czech Republic, Vídeňská 1083, CZ-14220 Prague 4, Czech Republic.
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21
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Zhang H, Gao N, Liu T, Fang Y, Qi B, Wen Q, Zhou J, Jia L, Qiao H. Effect of Cytochrome b5 Content on the Activity of Polymorphic CYP1A2, 2B6, and 2E1 in Human Liver Microsomes. PLoS One 2015; 10:e0128547. [PMID: 26046844 PMCID: PMC4457846 DOI: 10.1371/journal.pone.0128547] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 04/28/2015] [Indexed: 11/18/2022] Open
Abstract
Human cytochrome b5 (Cyt b5) plays important roles in cytochrome P450 (CYP)-mediated drug metabolism. However, the expression level of Cyt b5 in normal human liver remains largely unknown. The effect of Cyt b5 on overall CYP activity in human liver microsomes (HLM) has rarely been reported and the relationship between Cyt b5 and the activity of polymorphic CYP has not been systematically investigated. In this study, we found that the median value of Cyt b5 protein was 270.01 pmol/mg from 123 HLM samples, and 12- and 19-fold individual variation was observed in Cyt b5 mRNA and protein levels, respectively. Gender and smoking clearly influenced Cyt b5 content. In addition, we found that Cyt b5 protein levels significantly correlated with the overall activity of CYP1A2, 2B6, and 2E1 in HLM. However, when the CYP activities were sorted by single nucleotide polymorphisms (SNP), the effect of Cyt b5 protein on the kinetic parameters varied greatly. There were significant correlations between Cyt b5 content and Vmax and CLint of CYP1A2 wild-types (3860GG, 2159GG, and 5347CC) as well as homozygous mutants (163AA and 3113GG). In contrast to Vmax and CLint, the Km of CYP2B6 516GG and 785AA genotypes was inversely associated with Cyt b5 content. Correlations between Cyt b5 content and Vmax and CLint of CYP2E1 -1293GG, -1293GC, 7632TT, 7632TA, -333TT, and -352AA genotypes were also observed. In conclusion, Cyt b5 expression levels varied considerably in the Chinese cohort from this study. Cyt b5 had significant impact on the overall activity of CYP1A2, 2B6, and 2E1 in HLM and the effects of Cyt b5 protein on polymorphic CYP1A2, 2B6, and 2E1 activity were SNP-dependent. These findings suggest that Cyt b5 plays an important role in CYP-mediated activities in HLM and may possibly be a contributing factor for the individual variation observed in CYP enzyme activities.
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Affiliation(s)
- Haifeng Zhang
- Institute of Clinical Pharmacology, Zhengzhou University, Zhengzhou, China
| | - Na Gao
- Institute of Clinical Pharmacology, Zhengzhou University, Zhengzhou, China
| | - Tingting Liu
- Institute of Clinical Pharmacology, Zhengzhou University, Zhengzhou, China
| | - Yan Fang
- Institute of Clinical Pharmacology, Zhengzhou University, Zhengzhou, China
| | - Bing Qi
- Institute of Clinical Pharmacology, Zhengzhou University, Zhengzhou, China
| | - Qiang Wen
- Institute of Clinical Pharmacology, Zhengzhou University, Zhengzhou, China
| | - Jun Zhou
- Institute of Clinical Pharmacology, Zhengzhou University, Zhengzhou, China
| | - Linjing Jia
- Institute of Clinical Pharmacology, Zhengzhou University, Zhengzhou, China
| | - Hailing Qiao
- Institute of Clinical Pharmacology, Zhengzhou University, Zhengzhou, China
- * E-mail:
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22
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Davydov DR, Davydova NY, Sineva EV, Halpert JR. Interactions among cytochromes P450 in microsomal membranes: oligomerization of cytochromes P450 3A4, 3A5, and 2E1 and its functional consequences. J Biol Chem 2015; 290:3850-64. [PMID: 25533469 PMCID: PMC4319048 DOI: 10.1074/jbc.m114.615443] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 12/02/2014] [Indexed: 12/31/2022] Open
Abstract
The body of evidence of physiologically relevant P450-P450 interactions in microsomal membranes continues to grow. Here we probe oligomerization of human CYP3A4, CYP3A5, and CYP2E1 in microsomal membranes. Using a technique based on luminescence resonance energy transfer, we demonstrate that all three proteins are subject to a concentration-dependent equilibrium between the monomeric and oligomeric states. We also observed the formation of mixed oligomers in CYP3A4/CYP3A5, CYP3A4/CYP2E1, and CYP3A5/CYP2E1 pairs and demonstrated that the association of either CYP3A4 or CYP3A5 with CYP2E1 causes activation of the latter enzyme. Earlier we hypothesized that the intersubunit interface in CYP3A4 oligomers is similar to that observed in the crystallographic dimers of some microsomal drug-metabolizing cytochromes P450 (Davydov, D. R., Davydova, N. Y., Sineva, E. V., Kufareva, I., and Halpert, J. R. (2013) Pivotal role of P450-P450 interactions in CYP3A4 allostery: the case of α-naphthoflavone. Biochem. J. 453, 219-230). Here we report the results of intermolecular cross-linking of CYP3A4 oligomers with thiol-reactive bifunctional reagents as well as the luminescence resonance energy transfer measurements of interprobe distances in the oligomers of labeled CYP3A4 single-cysteine mutants. The results provide compelling support for the physiological relevance of the dimer-specific peripheral ligand-binding site observed in certain CYP3A4 structures. According to our interpretation, these results reveal an important general mechanism that regulates the activity and substrate specificity of the cytochrome P450 ensemble through interactions between multiple P450 species. As a result of P450-P450 cross-talk, the catalytic properties of the cytochrome P450 ensemble cannot be predicted by simple summation of the properties of the individual P450 species.
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Affiliation(s)
- Dmitri R Davydov
- From the Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California 92093 and the V. N. Orekhovich Institute of Biomedical Chemistry, Russian Academy of Medical Sciences, 10 Pogodinskaya Str., Moscow 119832, Russia
| | - Nadezhda Y Davydova
- From the Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California 92093 and
| | - Elena V Sineva
- From the Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California 92093 and
| | - James R Halpert
- From the Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California 92093 and
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23
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Henderson CJ, McLaughlin LA, Scheer N, Stanley LA, Wolf CR. Cytochrome b5 is a major determinant of human cytochrome P450 CYP2D6 and CYP3A4 activity in vivo. Mol Pharmacol 2015; 87:733-9. [PMID: 25657337 DOI: 10.1124/mol.114.097394] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The cytochrome P450-dependent mono-oxygenase system is responsible for the metabolism and disposition of chemopreventive agents, chemical toxins and carcinogens, and >80% of therapeutic drugs. Cytochrome P450 (P450) activity is regulated transcriptionally and by the rate of electron transfer from P450 reductase. In vitro studies have demonstrated that cytochrome b5 (Cyb5) also modulates P450 function. We recently showed that hepatic deletion of Cyb5 in the mouse (HBN) markedly alters in vivo drug pharmacokinetics; a key outstanding question is whether Cyb5 modulates the activity of the major human P450s in drug disposition in vivo. To address this, we crossed mice humanized for CYP2D6 or CYP3A4 with mice carrying a hepatic Cyb5 deletion. In vitro triazolam 4-hydroxylation (probe reaction for CYP3A4) was reduced by >50% in hepatic microsomes from CYP3A4-HBN mice compared with controls. Similar reductions in debrisoquine 4-hydroxylation and metoprolol α-hydroxylation were observed using CYP2D6-HBN microsomes, indicating a significant role for Cyb5 in the activity of both enzymes. This effect was confirmed by the concentration-dependent restoration of CYP3A4-mediated triazolam turnover and CYP2D6-mediated bufuralol and debrisoquine turnover on addition of Escherichia coli membranes containing recombinant Cyb5. In vivo, the peak plasma concentration and area under the concentration time curve from 0 to 8 hours (AUC0-8 h) of triazolam were increased 4- and 5.7-fold, respectively, in CYP3A4-HBN mice. Similarly, the pharmacokinetics of bufuralol and debrisoquine were significantly altered in CYP2D6-HBN mice, the AUC0-8 h being increased ∼1.5-fold and clearance decreased by 40-60%. These data demonstrate that Cyb5 can be a major determinant of CYP3A4 and CYP2D6 activity in vivo, with a potential impact on the metabolism, efficacy, and side effects of numerous therapeutic drugs.
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Affiliation(s)
- Colin J Henderson
- Medical Research Institute, University of Dundee, Ninewells Hospital and Medical School, University of Dundee, Dundee, United Kingdom (C.J.H., L.A.M., C.R.W.), TaconicArtemis, Cologne, Germany (N.S.); and Consultant in Investigative Toxicology, Linlithgow, United Kingdom (L.A.S.)
| | - Lesley A McLaughlin
- Medical Research Institute, University of Dundee, Ninewells Hospital and Medical School, University of Dundee, Dundee, United Kingdom (C.J.H., L.A.M., C.R.W.), TaconicArtemis, Cologne, Germany (N.S.); and Consultant in Investigative Toxicology, Linlithgow, United Kingdom (L.A.S.)
| | - Nico Scheer
- Medical Research Institute, University of Dundee, Ninewells Hospital and Medical School, University of Dundee, Dundee, United Kingdom (C.J.H., L.A.M., C.R.W.), TaconicArtemis, Cologne, Germany (N.S.); and Consultant in Investigative Toxicology, Linlithgow, United Kingdom (L.A.S.)
| | - Lesley A Stanley
- Medical Research Institute, University of Dundee, Ninewells Hospital and Medical School, University of Dundee, Dundee, United Kingdom (C.J.H., L.A.M., C.R.W.), TaconicArtemis, Cologne, Germany (N.S.); and Consultant in Investigative Toxicology, Linlithgow, United Kingdom (L.A.S.)
| | - C Roland Wolf
- Medical Research Institute, University of Dundee, Ninewells Hospital and Medical School, University of Dundee, Dundee, United Kingdom (C.J.H., L.A.M., C.R.W.), TaconicArtemis, Cologne, Germany (N.S.); and Consultant in Investigative Toxicology, Linlithgow, United Kingdom (L.A.S.)
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Stiborová M, Černá V, Moserová M, Mrízová I, Arlt VM, Frei E. The anticancer drug ellipticine activated with cytochrome P450 mediates DNA damage determining its pharmacological efficiencies: studies with rats, Hepatic Cytochrome P450 Reductase Null (HRN™) mice and pure enzymes. Int J Mol Sci 2014; 16:284-306. [PMID: 25547492 PMCID: PMC4307247 DOI: 10.3390/ijms16010284] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2014] [Accepted: 12/17/2014] [Indexed: 12/30/2022] Open
Abstract
Ellipticine is a DNA-damaging agent acting as a prodrug whose pharmacological efficiencies and genotoxic side effects are dictated by activation with cytochrome P450 (CYP). Over the last decade we have gained extensive experience in using pure enzymes and various animal models that helped to identify CYPs metabolizing ellipticine. In this review we focus on comparison between the in vitro and in vivo studies and show a necessity of both approaches to obtain valid information on CYP enzymes contributing to ellipticine metabolism. Discrepancies were found between the CYP enzymes activating ellipticine to 13-hydroxy- and 12-hydroxyellipticine generating covalent DNA adducts and those detoxifying this drug to 9-hydroxy- and 7-hydroellipticine in vitro and in vivo. In vivo, formation of ellipticine-DNA adducts is dependent not only on expression levels of CYP3A, catalyzing ellipticine activation in vitro, but also on those of CYP1A that oxidize ellipticine in vitro mainly to the detoxification products. The finding showing that cytochrome b5 alters the ratio of ellipticine metabolites generated by CYP1A1/2 and 3A4 explained this paradox. Whereas the detoxification of ellipticine by CYP1A and 3A is either decreased or not changed by cytochrome b5, activation leading to ellipticine-DNA adducts increased considerably. We show that (I) the pharmacological effects of ellipticine mediated by covalent ellipticine-derived DNA adducts are dictated by expression levels of CYP1A, 3A and cytochrome b5, and its own potency to induce these enzymes in tumor tissues, (II) animal models, where levels of CYPs are either knocked out or induced are appropriate to identify CYPs metabolizing ellipticine in vivo, and (III) extrapolation from in vitro data to the situation in vivo is not always possible, confirming the need for these animal models.
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Affiliation(s)
- Marie Stiborová
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, CZ-12843 Prague 2, Czech Republic.
| | - Věra Černá
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, CZ-12843 Prague 2, Czech Republic.
| | - Michaela Moserová
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, CZ-12843 Prague 2, Czech Republic.
| | - Iveta Mrízová
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, CZ-12843 Prague 2, Czech Republic.
| | - Volker M Arlt
- Analytical and Environmental Sciences Division, MRC-PHE Centre for Environmental & Health, King's College London, 150 Stamford Street, London SE1 9NH, UK.
| | - Eva Frei
- Division of Preventive Oncology, National Center for Tumor Diseases, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
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Regulation of cytochrome b5 expression by miR-223 in human liver: effects on cytochrome P450 activities. Pharm Res 2014; 31:780-94. [PMID: 24078287 DOI: 10.1007/s11095-013-1200-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2013] [Accepted: 08/31/2013] [Indexed: 01/24/2023]
Abstract
PURPOSE Cytochrome b5 (b5) is a hemoprotein that transfers electrons to several enzymes to fulfill functions in fatty acid desaturation, methemoglobin reduction, steroidogenesis, and drug metabolism. Despite the importance of b5, the regulation of b5 expression in human liver remains largely unknown. We investigated whether microRNA (miRNA) might be involved in the regulation of human b5. METHODS Twenty-four human liver specimens were used for correlation analysis. In silico analysis and luciferase assay were performed to determine whether the predicted miRNAs functionally target to b5. The miR-223 was overexpressed into HepG2 cells infected with adenovirus expressing human cytochrome P450. RESULTS In human livers, the b5 protein levels were not positively correlated with the b5 mRNA levels, and miR-223 levels were inversely correlated with the b5 mRNA levels or the translational efficiencies. The luciferase assay showed that miR-223 functionally binds to the element in the 3′-untranslated region of b5 mRNA. The overexpression of miR-223 significantly reduced the endogenous b5 protein level and the mRNA stability in HepG2 cells. Moreover, the overexpression of miR-223 significantly reduced CYP3A4-catalyzed testosterone 6β-hydroxylation activity and CYP2E1-catalyzed chlorzoxazone 6-hydroxylase activity but not CYP1A2-catalyzed 7-ethoxyresorufin O-deethylase activity. CONCLUSIONS miR-223 down-regulates b5 expression in the human liver, modulating P450 activities.
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Kandel SE, Lampe JN. Role of protein-protein interactions in cytochrome P450-mediated drug metabolism and toxicity. Chem Res Toxicol 2014; 27:1474-86. [PMID: 25133307 PMCID: PMC4164225 DOI: 10.1021/tx500203s] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
![]()
Through their unique oxidative chemistry,
cytochrome P450 monooxygenases
(CYPs) catalyze the elimination of most drugs and toxins from the
human body. Protein–protein interactions play a critical role
in this process. Historically, the study of CYP–protein interactions
has focused on their electron transfer partners and allosteric mediators,
cytochrome P450 reductase and cytochrome b5. However, CYPs can bind
other proteins that also affect CYP function. Some examples include
the progesterone receptor membrane component 1, damage resistance
protein 1, human and bovine serum albumin, and intestinal fatty acid
binding protein, in addition to other CYP isoforms. Furthermore, disruption
of these interactions can lead to altered paths of metabolism and
the production of toxic metabolites. In this review, we summarize
the available evidence for CYP protein–protein interactions
from the literature and offer a discussion of the potential impact
of future studies aimed at characterizing noncanonical protein–protein
interactions with CYP enzymes.
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Affiliation(s)
- Sylvie E Kandel
- XenoTech, LLC , 16825 West 116th Street, Lenexa, Kansas 66219, United States
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Ramsden D, Tweedie DJ, Chan TS, Tracy TS. Altered CYP2C9 activity following modulation of CYP3A4 levels in human hepatocytes: an example of protein-protein interactions. Drug Metab Dispos 2014; 42:1940-6. [PMID: 25157098 DOI: 10.1124/dmd.114.057901] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cytochrome P450 (P450) protein-protein interactions resulting in modulation of enzyme activities have been well documented using recombinant isoforms. This interaction has been less clearly demonstrated in a more physiologic in vitro system such as human hepatocytes. As an expansion of earlier work (Subramanian et al., 2010), in which recombinant CYP2C9 activity decreased with increasing levels of CYP3A4, the current study modulated CYP3A4 content in human hepatocytes to determine the impact on CYP2C9. Modulation of CYP3A4 levels in situ was enabled by the use of a long-term human hepatocyte culture model (HepatoPac) shown to retain phenotypic hepatocyte function over a number of weeks. The extended period of culture allowed time for knockdown of CYP3A4 protein by small interfering RNA (siRNA) with subsequent recovery, as well as upregulation through induction with a recovery period. CYP3A4 gene silencing resulted in a 60% decrease in CYP3A4 activity and protein levels with a concomitant 74% increase in CYP2C9 activity, with no change in CYP2C9 mRNA levels. Upon removal of siRNA, both CYP2C9 and CYP3A4 activities returned to pre-knockdown levels. Importantly, modulation of CYP3A4 protein levels had no impact on cytochrome P450 reductase activities or levels. However, the possibility for competition for limiting reductase cannot be ruled out. Interestingly, lowering CYP3A4 levels also increased UDP-glucuronosyltransferase 2B7 activity. These studies clearly demonstrate that alterations in CYP3A4 levels can modulate CYP2C9 activity in situ and suggest that further studies are warranted to evaluate the possible clinical consequences of these findings.
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Affiliation(s)
- Diane Ramsden
- Drug Metabolism and Pharmacokinetics, Boehringer Ingelheim Pharmaceuticals, Ridgefield, Connecticut (D.R., D.J.T., T.S.C.); and Department of Pharmaceutical Sciences, University of Kentucky, Lexington, Kentucky (T.S.T.)
| | - Donald J Tweedie
- Drug Metabolism and Pharmacokinetics, Boehringer Ingelheim Pharmaceuticals, Ridgefield, Connecticut (D.R., D.J.T., T.S.C.); and Department of Pharmaceutical Sciences, University of Kentucky, Lexington, Kentucky (T.S.T.)
| | - Tom S Chan
- Drug Metabolism and Pharmacokinetics, Boehringer Ingelheim Pharmaceuticals, Ridgefield, Connecticut (D.R., D.J.T., T.S.C.); and Department of Pharmaceutical Sciences, University of Kentucky, Lexington, Kentucky (T.S.T.)
| | - Timothy S Tracy
- Drug Metabolism and Pharmacokinetics, Boehringer Ingelheim Pharmaceuticals, Ridgefield, Connecticut (D.R., D.J.T., T.S.C.); and Department of Pharmaceutical Sciences, University of Kentucky, Lexington, Kentucky (T.S.T.)
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Peng HM, Auchus RJ. Two surfaces of cytochrome b5 with major and minor contributions to CYP3A4-catalyzed steroid and nifedipine oxygenation chemistries. Arch Biochem Biophys 2013; 541:53-60. [PMID: 24256945 DOI: 10.1016/j.abb.2013.11.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 10/22/2013] [Accepted: 11/04/2013] [Indexed: 10/26/2022]
Abstract
Conserved human cytochrome b5 (b5) residues D58 and D65 are critical for interactions with CYP2E1 and CYP2C19, whereas E48 and E49 are essential for stimulating the 17,20-lyase activity of CYP17A1. Here, we show that b5 mutations E48G, E49G, D58G, and D65G have reduced capacity to stimulate CYP3A4-catalyzed progesterone and testosterone 6β-hydroxylation or nifedipine oxidation. The b5 double mutation D58G/D65G fails to stimulate these reactions, similar to CYP2E1 and CYP2C19, whereas mutation E48G/E49G retains 23-42% of wild-type stimulation. Neither mutation impairs the activity stimulation of wild-type b5, nor does mutation D58G/D65G impair the partial stimulation of mutations E48G or E48G/E49G. For assays reconstituted with a single phospholipid, phosphatidyl serine afforded the highest testosterone 6β-hydroxylase activity with wild-type b5 but the poorest activity with b5 mutation E48G/E49G, and the activity stimulation of mutation E48G/E49G was lost at [NaCl]>50mM. Cross-linking of CYP3A4 and b5 decreased in the order wild-type>E48G/E49G>D58G/D65G and varied with phospholipid. We conclude that two b5 acidic surfaces, primarily the domain including residues D58-D65, participate in the stimulation of CYP3A4 activities. Our data suggest that a minor population of CYP3A4 molecules remains sensitive to b5 mutation E48G/E49G, consistent with phospholipid-dependent conformational heterogeneity of CYP3A4.
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Affiliation(s)
- Hwei-Ming Peng
- Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, United States
| | - Richard J Auchus
- Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, United States.
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Johnson EF, Connick JP, Reed JR, Backes WL, Desai MC, Xu L, Estrada DF, Laurence JS, Scott EE. Correlating structure and function of drug-metabolizing enzymes: progress and ongoing challenges. Drug Metab Dispos 2013; 42:9-22. [PMID: 24130370 DOI: 10.1124/dmd.113.054627] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
This report summarizes a symposium sponsored by the American Society for Pharmacology and Experimental Therapeutics at Experimental Biology held April 20-24 in Boston, MA. Presentations discussed the status of cytochrome P450 (P450) knowledge, emphasizing advances and challenges in relating structure with function and in applying this information to drug design. First, at least one structure of most major human drug-metabolizing P450 enzymes is known. However, the flexibility of these active sites can limit the predictive value of one structure for other ligands. A second limitation is our coarse-grain understanding of P450 interactions with membranes, other P450 enzymes, NADPH-cytochrome P450 reductase, and cytochrome b5. Recent work has examined differential P450 interactions with reductase in mixed P450 systems and P450:P450 complexes in reconstituted systems and cells, suggesting another level of functional control. In addition, protein nuclear magnetic resonance is a new approach to probe these protein/protein interactions, identifying interacting b5 and P450 surfaces, showing that b5 and reductase binding are mutually exclusive, and demonstrating ligand modulation of CYP17A1/b5 interactions. One desired outcome is the application of such information to control drug metabolism and/or design selective P450 inhibitors. A final presentation highlighted development of a CYP3A4 inhibitor that slows clearance of human immunodeficiency virus drugs otherwise rapidly metabolized by CYP3A4. Although understanding P450 structure/function relationships is an ongoing challenge, translational advances will benefit from continued integration of existing and new biophysical approaches.
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Affiliation(s)
- Eric F Johnson
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California (E.F.J.); Department of Pharmacology and Experimental Therapeutics and the Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, New Orleans, Louisiana (J.P.C., J.R.R., W.L.B.); Department of Medicinal Chemistry, Gilead Sciences, Inc., Foster City, California (M.C.D., L.X.); Department of Pharmaceutical Chemistry (J.S.L.) and Department of Medicinal Chemistry (D.F.E., E.E.S.), University of Kansas, Lawrence, Kansas
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Henderson CJ, McLaughlin LA, Finn RD, Ronseaux S, Kapelyukh Y, Wolf CR. A role for cytochrome b5 in the In vivo disposition of anticancer and cytochrome P450 probe drugs in mice. Drug Metab Dispos 2013; 42:70-7. [PMID: 24115751 DOI: 10.1124/dmd.113.055277] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The role of microsomal cytochrome b5 (Cyb5) in defining the rate of drug metabolism and disposition has been intensely debated for several decades. Recently we described mouse models involving the hepatic or global deletion of Cyb5, demonstrating its central role in in vivo drug disposition. We have now used the cytochrome b5 complete null (BCN) model to determine the role of Cyb5 in the metabolism of ten pharmaceuticals metabolized by a range of cytochrome P450s, including five anticancer drugs, in vivo and in vitro. The extent to which metabolism was significantly affected by the absence of Cyb5 was substrate-dependent; AUC increased (75-245%) and clearance decreased (35-72%) for phenacetin, metoprolol, and chlorzoxazone. Tolbutamide disposition was not significantly altered by Cyb5 deletion, while for midazolam clearance was decreased by 66%. The absence of Cyb5 had no effect on gefitinib and paclitaxel disposition, while significant changes in the in vivo pharmacokinetics were measured for: cyclophosphamide [maximum plasma concentration (Cmax) and terminal half-life increased 55% and 40%, respectively], tamoxifen (AUClast and Cmax increased 370% and 233%, respectively), and anastrozole (AUC and terminal half-life increased 125% and 62%, respectively; clearance down 80%). These data provide strong evidence that both hepatic and extrahepatic Cyb5 levels are an important determinant of in vivo drug disposition catalyzed by a range of cytochrome P450s, including currently prescribed anticancer agents, and that individuality in Cyb5 expression could be a significant determinant in rates of drug disposition in man.
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Affiliation(s)
- Colin J Henderson
- Division of Cancer Research, Medical Research Institute, University of Dundee, and Ninewells Hospital and Medical School, Dundee, United Kingdom
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Functional characterization of eight human CYP1A2 variants: the role of cytochrome b5. Pharmacogenet Genomics 2013; 23:41-52. [PMID: 23295917 DOI: 10.1097/fpc.0b013e32835c2ddf] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Interindividual variability in cytochrome P450 (CYP)-mediated xenobiotic metabolism is extensive. CYP metabolism requires two electrons, which can be donated by NADPH cytochrome P450 oxidoreductase (CYPOR) and/or cytochrome b5 (b5). Although substantial number of studies have reported on the function and effect of b5 in CYP-mediated catalysis, its mode of action is still not fully understood. OBJECTIVE The aim of this work was to examine the effect of b5 on the activities of eight natural-occurring variants of human CYP1A2, namely, T83M, S212C, S298R, G299S, I314V, I386F, C406Y, and R456H. MATERIALS AND METHODS An approach, as used in our former study was applied, coexpressing these polymorphic CYP1A2 variants separately with CYPOR and b5 in the bacterial cell model BTC-CYP. For each variant, 16 different activity parameters were measured, using eight different substrates. This heterogeneous data set was merged with the one of our former study (i.e. without b5) and a multivariate analysis was carried out. RESULTS This analysis indicated that b5 seems to have the ability to affect CYP1A2 variants to behave more like the wild-type variant. This was especially the case for variant I386F, for which the presence of b5 was crucial to show activity. Variants T83M and C406Y showed considerably different activity-profiles when in the presence of b5. Furthermore, our data seem to implicate CYP1A2 residue G299 in its interaction with CYPOR and/or b5. CONCLUSION Results indicate the ability of b5 to affect CYP1A2 variants to behave more like the wild-type variant, attenuating detrimental effects of structural mutations of these variants, seemingly through extensive allosteric effects.
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Peng HM, Auchus RJ. The action of cytochrome b(5) on CYP2E1 and CYP2C19 activities requires anionic residues D58 and D65. Biochemistry 2012. [PMID: 23193974 DOI: 10.1021/bi301384n] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The capacity of cytochrome b(5) (b(5)) to influence cytochrome P450 activities has been extensively studied and physiologically validated. Apo-b(5) enhances the activities of CYP3A4, CYP2A6, CYP2C19, and CYP17A1 but not that of CYP2E1 or CYP2D6, suggesting that the b(5) interaction varies among P450s. We previously showed that b(5) residues E48 and E49 are required to stimulate the 17,20-lyase activity of CYP17A1, but these same residues might not mediate b(5) activation of other P450 reactions, such as CYP2E1-catalyzed oxygenations, which are insensitive to apo-b(5). Using purified P450, b(5), and reductase (POR) in reconstituted assays, the D58G/D65G double mutation, of residues located in a hydrophilic α-helix of b(5), totally abolished the ability to stimulate CYP2E1-catalyzed chlorzoxazone 6-hydroxylation. In sharp contrast, the D58G/D65G double mutation retained the full ability to stimulate the 17,20-lyase activity of CYP17A1. The D58G/D65G double mutation competes poorly with wild-type b(5) for binding to the CYP2E1·POR complex yet accepts electrons from POR at a similar rate. Furthermore, the phospholipid composition markedly influences P450 turnover and b(5) stimulation and specificity, particularly for CYP17A1, in the following order: phosphatidylserine > phosphatidylethanolamine > phosphatidylcholine. The D58G/D65G double mutation also failed to stimulate CYP2C19-catalyzed (S)-mephenytoin 4-hydroxylation, whereas the E48G/E49G double mutation stimulated these activities of CYP2C19 and CYP2E1 equivalent to wild-type b(5). We conclude that b(5) residues D58 and D65 are essential for the stimulation of CYP2E1 and CYP2C19 activities and that the phospholipid composition significantly influences the b(5)-P450 interaction. At least two surfaces of b(5) differentially influence P450 activities, and the critical residues for individual P450 reactions cannot be predicted from sensitivity to apo-b(5) alone.
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Affiliation(s)
- Hwei-Ming Peng
- Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA
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Zhao C, Gao Q, Roberts AG, Shaffer SA, Doneanu CE, Xue S, Goodlett DR, Nelson SD, Atkins WM. Cross-linking mass spectrometry and mutagenesis confirm the functional importance of surface interactions between CYP3A4 and holo/apo cytochrome b(5). Biochemistry 2012; 51:9488-500. [PMID: 23150942 DOI: 10.1021/bi301069r] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cytochrome b(5) (cyt b(5)) is one of the key components in the microsomal cytochrome P450 monooxygenase system. Consensus has not been reached about the underlying mechanism of cyt b(5) modulation of CYP catalysis. Both cyt b(5) and apo b(5) are reported to stimulate the activity of several P450 isoforms. In this study, the surface interactions of both holo and apo b(5) with CYP3A4 were investigated and compared for the first time. Chemical cross-linking coupled with mass spectrometric analysis was used to identify the potential electrostatic interactions between the protein surfaces. Subsequently, the models of interaction of holo/apo b(5) with CYP3A4 were built using the identified interacting sites as constraints. Both cyt b(5) and apo b(5) were predicted to bind to the same groove on CYP3A4 with close contacts to the B-B' loop of CYP3A4, a substrate recognition site. Mutagenesis studies further confirmed that the interacting sites on CYP3A4 (Lys96, Lys127, and Lys421) are functionally important. Mutation of these residues reduced or abolished cyt b(5) binding affinity. The critical role of Arg446 on CYP3A4 in binding to cyt b(5) and/or cytochrome P450 reductase was also discovered. The results indicated that electrostatic interactions on the interface of the two proteins are functionally important. The results indicate that apo b(5) can dock with CYP3A4 in a manner analogous to that of holo b(5), so electron transfer from cyt b(5) is not required for its effects.
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Affiliation(s)
- Chunsheng Zhao
- Department of Medicinal Chemistry, University of Washington, Box 357610, Seattle, WA 98195, USA
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Abstract
Previous studies have shown that the presence of one P450 enzyme can affect the function of another. The goal of the present study was to determine if P450 enzymes are capable of forming homomeric complexes that affect P450 function. To address this problem, the catalytic activities of several P450s were examined in reconstituted systems containing NADPH-POR (cytochrome P450 reductase) and a single P450. CYP2B4 (cytochrome P450 2B4)-, CYP2E1 (cytochrome P450 2E1)- and CYP1A2 (cytochrome P450 1A2)-mediated activities were measured as a function of POR concentration using reconstituted systems containing different concentrations of P450. Although CYP2B4-dependent activities could be explained by a simple Michaelis-Menten interaction between POR and CYP2B4, both CYP2E1 and CYP1A2 activities generally produced a sigmoidal response as a function of [POR]. Interestingly, the non-Michaelis behaviour of CYP1A2 could be converted into a simple mass-action response by increasing the ionic strength of the buffer. Next, physical interactions between CYP1A2 enzymes were demonstrated in reconstituted systems by chemical cross-linking and in cellular systems by BRET (bioluminescence resonance energy transfer). Cross-linking data were consistent with the kinetic responses in that both were similarly modulated by increasing the ionic strength of the surrounding solution. Taken together, these results show that CYP1A2 forms CYP1A2-CYP1A2 complexes that exhibit altered catalytic activity.
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Ellipticine oxidation and DNA adduct formation in human hepatocytes is catalyzed by human cytochromes P450 and enhanced by cytochrome b5. Toxicology 2012; 302:233-41. [PMID: 22917556 DOI: 10.1016/j.tox.2012.08.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2012] [Revised: 08/05/2012] [Accepted: 08/06/2012] [Indexed: 11/24/2022]
Abstract
Ellipticine is an antineoplastic agent considered a pro-drug, the pharmacological and genotoxic effects of which are dependent on cytochrome P450 (CYP)- and/or peroxidase-mediated activation to covalent DNA adducts. We investigated whether ellipticine-DNA adducts are formed in human hepatic microsomes and human hepatocytes. We then identified which human CYPs oxidize ellipticine to metabolites forming DNA adducts and the effect of cytochrome b(5) on this oxidation. 13-Hydroxyellipticine, the metabolite forming the major ellipticine-DNA adduct, was generated mainly by CYP3A4 and 1A1, followed by CYP2D6>2C19>1B1>1A2>2E1 and >2C9. Cytochrome b(5) increased formation of this metabolite by human CYPs, predominantly by CYP1A1, 3A4, 1A2 and 2C19. Formation of 12-hydroxyellipticine is generated mainly by CYP2C19, followed by CYP2C9>3A4>2D6>2E1 and >2A6. Other CYPs were less active (CYP2C8 and 2B6) or did not oxidize ellipticine to this metabolite (CYP1A1, 1A2 and 1B1). CYP2D6 was the most efficient enzyme generating ellipticine N(2)-oxide. CYP3A4 and 1A1 in the presence of cytochrome b(5) are mainly responsible for bioactivation of ellipticine to DNA adduct 1 (formed by ellipticine-13-ylium from 13-hydroxyellipticine), while 12-hydroxyellipticine generated during the CYP2C19-mediated ellipticine oxidation is the predominant metabolite forming ellipticine-12-ylium that generates ellipticine-DNA adduct 2. These ellipticine-DNA adducts were also generated by human hepatic microsomes and in primary human hepatocytes exposed to ellipticine. Ellipticine is toxic to these hepatocytes, decreasing their viability; the IC(50) value of ellipticine in these cells was 0.7 μM. In liver CYP3A4 is the predominant ellipticine activating CYP species, which is expected to result in efficient metabolism after oral ingestion of ellipticine in humans.
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Sushko TA, Gilep AA, Usanov SA. Mechanism of intermolecular interactions of microsomal cytochrome P450s CYP17 and CYP21 involved in steroid hormone biosynthesis. BIOCHEMISTRY (MOSCOW) 2012; 77:585-92. [DOI: 10.1134/s0006297912060041] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Bakken GV, Molden E, Knutsen K, Lunder N, Hermann M. Metabolism of the active metabolite of quetiapine, N-desalkylquetiapine in vitro. Drug Metab Dispos 2012; 40:1778-84. [PMID: 22688609 DOI: 10.1124/dmd.112.045237] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The antipsychotic drug quetiapine has been approved for the treatment of unipolar and bipolar depression. The antidepressant activity is considered to be mediated by the active metabolite N-desalkylquetiapine, which is mainly formed by CYP3A4. Little is known about the subsequent elimination of this metabolite. Therefore, this study investigated the possible involvement of cytochrome P450 (P450) enzymes in the metabolism of N-desalkylquetiapine. Screening for and interpretation of metabolites were performed by incubating N-desalkylquetiapine in human liver microsomes (HLM) followed by liquid chromatography-tandem mass spectrometry. The possible involvement of P450 enzymes in N-desalkylquetiapine metabolism was evaluated by coincubation of selective P450 inhibitors in HLM and subsequent experiments with recombinant human P450 enzymes. In HLM experiments, three chromatographic peaks were interpreted as possible metabolites of N-desalkylquetiapine, namely, N-desalkylquetiapine sulfoxide, 7-hydroxy-N-desalkylquetiapine, and an unrecognized metabolite (denoted M3). Inhibition of CYP2D6 (by quinidine) reduced formation of 7-hydroxy-N-desalkylquetiapine by 81%, whereas the CYP3A4 inhibitor ketoconazole inhibited formation of N-desalkylquetiapine sulfoxide and M3 by 65 and 34%, respectively. Inhibitors of CYP1A2, CYP2C9, and CYP2C19 showed only limited changes in metabolite formation. In recombinant systems, 7-hydroxy-N-desalkylquetiapine was exclusively formed by CYP2D6, whereas N-desalkylquetiapine sulfoxide and M3 were formed by both CYP3A4 and CYP2D6. Overall, intrinsic clearance of N-desalkylquetiapine was 12-fold higher by recombinant CYP2D6 relative to CYP3A4. In conclusion, N-desalkylquetiapine is metabolized by both CYP2D6 and CYP3A4 in vitro with preference for the former enzyme. The pharmacologically active metabolite, 7-hydroxy-N-desalkylquetiapine, was exclusively formed by CYP2D6, whereas the two other metabolites were mainly formed by CYP3A4.
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Affiliation(s)
- Gry Vibeke Bakken
- Center for Psychopharmacology, Diakonhjemmet Hospital, P.O. Box 85, Vinderen, N-0319 Oslo, Norway.
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Stiborová M, Indra R, Moserová M, Černá V, Rupertová M, Martínek V, Eckschlager T, Kizek R, Frei E. Cytochrome b5 Increases Cytochrome P450 3A4-Mediated Activation of Anticancer Drug Ellipticine to 13-Hydroxyellipticine Whose Covalent Binding to DNA Is Elevated by Sulfotransferases and N,O-Acetyltransferases. Chem Res Toxicol 2012; 25:1075-85. [DOI: 10.1021/tx3000335] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Marie Stiborová
- Department of Biochemistry,
Faculty of Science, Charles University,
Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Radek Indra
- Department of Biochemistry,
Faculty of Science, Charles University,
Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Michaela Moserová
- Department of Biochemistry,
Faculty of Science, Charles University,
Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Věra Černá
- Department of Biochemistry,
Faculty of Science, Charles University,
Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Martina Rupertová
- Department of Biochemistry,
Faculty of Science, Charles University,
Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Václav Martínek
- Department of Biochemistry,
Faculty of Science, Charles University,
Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Tomáš Eckschlager
- Department of Pediatric Hematology
and Oncology, Charles University and University Hospital Motol, Prague, Czech Republic
| | - René Kizek
- Department of Chemistry and Biochemistry,
Faculty of Agronomy, Mendel University,
Brno, Czech Republic
| | - Eva Frei
- Division
of Preventive Oncology,
National Center for Tumor Diseases, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
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Reed JR, Backes WL. Formation of P450 · P450 complexes and their effect on P450 function. Pharmacol Ther 2011; 133:299-310. [PMID: 22155419 DOI: 10.1016/j.pharmthera.2011.11.009] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Accepted: 11/11/2011] [Indexed: 11/24/2022]
Abstract
Cytochromes P450 (P450) are membrane-bound enzymes that catalyze the monooxygenation of a diverse array of xenobiotic and endogenous compounds. The P450s responsible for foreign compound metabolism generally are localized in the endoplasmic reticulum of the liver, lung and small intestine. P450 enzymes do not act alone but require an interaction with other electron transfer proteins such as NADPH-cytochrome P450 reductase (CPR) and cytochrome b(5). Because P450s are localized in the endoplasmic reticulum with these and other ER-resident proteins, there is a potential for protein-protein interactions to influence P450 function. There has been increasing evidence that P450 enzymes form complexes in the ER, with compelling support that formation of P450 · P450 complexes can significantly influence their function. Our goal is to review the research supporting the formation of P450 · P450 complexes, their specificity, and how drug metabolism may be affected. This review describes the potential mechanisms by which P450s may interact, and provides evidence to support each of the possible mechanisms. Additionally, evidence for the formation of both heteromeric and homomeric P450 complexes are reviewed. Finally, direct physical evidence for P450 complex formation in solution and in membranes is summarized, and questions directing the future research of functional P450 interactions are discussed with respect to their potential impact on drug metabolism.
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Affiliation(s)
- James R Reed
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
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40
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Cytochrome b5 shifts oxidation of the anticancer drug ellipticine by cytochromes P450 1A1 and 1A2 from its detoxication to activation, thereby modulating its pharmacological efficacy. Biochem Pharmacol 2011; 82:669-80. [DOI: 10.1016/j.bcp.2011.06.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Revised: 06/03/2011] [Accepted: 06/03/2011] [Indexed: 01/19/2023]
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41
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Oda S, Nakajima M, Toyoda Y, Fukami T, Yokoi T. Progesterone Receptor Membrane Component 1 Modulates Human Cytochrome P450 Activities in an Isoform-Dependent Manner. Drug Metab Dispos 2011; 39:2057-65. [DOI: 10.1124/dmd.111.040907] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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42
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Crewe HK, Barter ZE, Yeo KR, Rostami-Hodjegan A. Are there differences in the catalytic activity per unit enzyme of recombinantly expressed and human liver microsomal cytochrome P450 2C9? A systematic investigation into inter-system extrapolation factors. Biopharm Drug Dispos 2011; 32:303-18. [PMID: 21725985 DOI: 10.1002/bdd.760] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Revised: 05/02/2011] [Accepted: 05/05/2011] [Indexed: 11/07/2022]
Abstract
The 'relative activity factor' (RAF) compares the activity per unit of microsomal protein in recombinantly expressed cytochrome P450 enzymes (rhCYP) and human liver without separating the potential sources of variation (i.e. abundance of enzyme per mg of protein or variation of activity per unit enzyme). The dimensionless 'inter-system extrapolation factor' (ISEF) dissects differences in activity from those in CYP abundance. Detailed protocols for the determination of this scalar, which is used in population in vitro-in vivo extrapolation (IVIVE), are currently lacking. The present study determined an ISEF for CYP2C9 and, for the first time, systematically evaluated the effects of probe substrate, cytochrome b5 and methods for assessing the intrinsic clearance (CL(int) ). Values of ISEF for S-warfarin, tolbutamide and diclofenac were 0.75 ± 0.18, 0.57 ± 0.07 and 0.37 ± 0.07, respectively, using CL(int) values derived from the kinetic values V(max) and K(m) of metabolite formation in rhCYP2C9 + reductase + b5 BD Supersomes™. The ISEF values obtained using rhCYP2C9 + reductase BD Supersomes™ were more variable, with values of 7.16 ± 1.25, 0.89 ± 0.52 and 0.50 ± 0.05 for S-warfarin, tolbutamide and diclofenac, respectively. Although the ISEF values obtained from rhCYP2C9 + reductase + b5 for the three probe substrates were statistically different (p < 0.001), the use of the mean value of 0.54 resulted in predicted oral clearance values for all three substrates within 1.4 fold of the observed literature values. For consistency in the relative activity across substrates, use of a b5 expressing recombinant system, with the intrinsic clearance calculated from full kinetic data is recommended for generation of the CYP2C9 ISEF. Furthermore, as ISEFs have been found to be sensitive to differences in accessory proteins, rhCYP system specific ISEFs are recommended.
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Affiliation(s)
- H K Crewe
- Academic Unit of Clinical Pharmacology, University of Sheffield, Royal Hallamshire Hospital, Sheffield, UK
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Davydov DR. Microsomal monooxygenase as a multienzyme system: the role of P450-P450 interactions. Expert Opin Drug Metab Toxicol 2011; 7:543-58. [PMID: 21395496 DOI: 10.1517/17425255.2011.562194] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION There is increasing evidence of physical interactions (association) among cytochromes P450 in the membranes of the endoplasmic reticulum. Functional consequences of these interactions are often underestimated. AREAS COVERED This article provides a comprehensive overview of available experimental material regarding P450-P450 interactions. Special emphasis is given to the interactions between different P450 species and to the functional consequences of homo- and heterooligomerization. EXPERT OPINION Recent advances provide conclusive evidence for a substantial degree of P450 oligomerization in membranes. Interactions between different P450 species resulting in the formation of mixed oligomers with altered activity and substrate specificity have been demonstrated clearly. There are important indications that oligomerization impedes electron flow to a fraction of the P450 population, which renders some P450 species nonfunctional. Functional consequences of P450-P450 interactions make the integrated properties of the microsomal monooxygenase remarkably different from a simple summation of the properties of the individual P450 species. This complexity compromises the predictive power of the current in vitro models of drug metabolism and warrants an urgent need for development of new model systems that consider the interactions of multiple P450 species.
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Affiliation(s)
- Dmitri R Davydov
- University of California - San Diego, Skaggs School of Pharmacy and Pharmaceutical Sciences, La Jolla, CA 92093, USA.
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Traylor MJ, Chai J, Clark DS. Simultaneous measurement of CYP1A2 activity, regioselectivity, and coupling: Implications for environmental sensitivity of enzyme-substrate binding. Arch Biochem Biophys 2010; 505:186-93. [PMID: 20933493 DOI: 10.1016/j.abb.2010.10.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Revised: 10/04/2010] [Accepted: 10/04/2010] [Indexed: 11/15/2022]
Abstract
The cytochrome P450 (CYP) reaction mechanism often yields a broad array of coupled and uncoupled products from a single substrate. While it is well known that reaction conditions can drastically affect the rate of P450 catalysis, their effects on regioselectivity and coupling are not well characterized. To investigate such effects, the CYP1A2 oxidation of 7-ethoxymethoxy-3-cyanocoumarin (EOMCC) was examined as a function of buffer type, buffer concentration, pH, and temperature. A high-throughput, optical method was developed to simultaneously measure the rate of substrate depletion, NADPH depletion, and generation of the O-dealkylated product. Increasing the phosphate buffer concentration and temperature increased both the NADPH and EOMCC depletion rates by 6-fold, whereas coupling was constant at 7.9% and the regioselectivity of O-dealkylation to other coupled pathways was constant at 21.7%. Varying the buffer type and pH increased NADPH depletion by 2.5-fold and EOMCC depletion by 3.5-fold; however, neither coupling nor regioselectivity was constant, with variations of 14.4% and 21.6%, respectively. Because the enzyme-substrate binding interaction is a primary determinant of both coupling and regioselectivity, it is reasonable to conclude that ionic strength, as varied by the buffer concentration, and temperature alter the rate without affecting binding while buffer type and pH alter both.
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Affiliation(s)
- Matthew J Traylor
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, 94720, United States
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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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46
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Swart AC, Storbeck KH, Swart P. A single amino acid residue, Ala 105, confers 16alpha-hydroxylase activity to human cytochrome P450 17alpha-hydroxylase/17,20 lyase. J Steroid Biochem Mol Biol 2010; 119:112-20. [PMID: 20043997 DOI: 10.1016/j.jsbmb.2009.12.014] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2009] [Revised: 12/17/2009] [Accepted: 12/21/2009] [Indexed: 11/19/2022]
Abstract
In adrenal steroidogenesis, CYP17 catalyses the 17alpha-hydroxylation of pregnenolone and progesterone and the subsequent 17,20-lyase reaction, yielding adrenal androgens. The enzyme exhibits distinctly different selectivities towards these substrates in various species. CYP17 has also been shown to exhibit 16alpha-hydroxylase activity towards progesterone in some species, with only human and chimp CYP17 catalysing the biosynthesis of substantial amounts of 16-OHprogesterone. The 16alpha-hydroxylase activity was investigated by introducing an Ala105Leu substitution into human CYP17. The converse mutation, Leu105Ala was introduced into the baboon, goat and pig enzymes. Wt human CYP17 converted approximately 30% progesterone to 16-OHprogesterone while the Ala105Leu mutant converted negligible amounts to 16-OHprogesterone ( approximately 9%), comparable to wt CYP17 of the other three species when expressed in COS-1 cells. The ratio of 17-hydroxylated products to 16-OHprogesterone of human CYP17 was 2.7 and that of the mutant human construct 10.5. Similar ratios were observed for human and goat CYP17 with the corresponding Ala or Leu residues. Although the Leu105Ala mutation of both baboon and pig CYP17 exhibited the same trend regarding the ratios, the rate of progesterone conversion was reduced. Coexpression with cytochrome b(5) significantly decreased the ratio of 17-hydroxylated products to 16-OHprogesterone in the Leu105 constructs, while effects were negligible with Ala at this position. Homology models show that Ala105 faces towards the active pocket in the predicted B'-C domain of CYP17. The smaller residue allows more flexibility of movement in the active pocket than Leu, presenting both the C16 and C17 of progesterone to the iron-oxy complex.
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Affiliation(s)
- Amanda C Swart
- Department of Biochemistry, University of Stellenbosch, Stellenbosch 7600, South Africa.
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47
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Subramanian M, Tam H, Zheng H, Tracy TS. CYP2C9-CYP3A4 protein-protein interactions: role of the hydrophobic N terminus. Drug Metab Dispos 2010; 38:1003-9. [PMID: 20215413 DOI: 10.1124/dmd.109.030155] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cytochromes P450 (P450s) interact with redox transfer proteins, including P450 reductase (CPR) and cytochrome b(5) (b5), all being membrane-bound. In multiple in vitro systems, P450-P450 interactions also have been observed, resulting in alterations in enzymatic activity. The current work investigated the effects and mechanisms of interaction between CYP2C9 and CYP3A4 in a reconstituted system. CYP2C9-mediated metabolism of S-naproxen and S-flurbiprofen was inhibited up to 80% by coincubation with CYP3A4, although K(m) values were unchanged. Increasing CYP3A4 concentrations increased the degree of inhibition, whereas increasing CPR concentrations resulted in less inhibition. Addition of b5 only marginally affected the magnitude of inhibition. In contrast, CYP2C9 did not alter the CYP3A4-mediated metabolism of testosterone. The potential role of the hydrophobic N terminus on these interactions was assessed by incubating truncated CYP2C9 with full-length CYP3A4, and vice versa. In both cases, the inhibition was fully abolished, indicating an important role for hydrophobic forces in CYP2C9-CYP3A4 interactions. Finally, a CYP2C9/CYP3A4 heteromer complex was isolated by coimmunoprecipitation techniques, confirming the physical interaction of the proteins. These results show that the N-terminal membrane binding domains of CYP2C9 and CYP3A4 are involved in heteromer complex formation and that at least one consequence is a reduction in CYP2C9 activity.
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Affiliation(s)
- Murali Subramanian
- Department of Experimental and Clinical Pharmacology, College of Pharmacy, University of Minnesota, Minneapolis, MN 55126, USA
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48
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Reed JR, Eyer M, Backes WL. Functional interactions between cytochromes P450 1A2 and 2B4 require both enzymes to reside in the same phospholipid vesicle: evidence for physical complex formation. J Biol Chem 2010; 285:8942-52. [PMID: 20071338 DOI: 10.1074/jbc.m109.076885] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Previous studies have shown that the combined presence of two cytochrome P450 enzymes (P450s) can affect the function of both enzymes, results that are consistent with the formation of heteromeric P450.P450 complexes. The goal of this study was to provide direct evidence for a physical interaction between P450 1A2 (CYP1A2) and P450 2B4 (CYP2B4), by determining if the interactions required both enzymes to reside in the same lipid vesicles. When NADPH-cytochrome P450 reductase (CPR) and a single P450 were incorporated into separate vesicles, extremely slow reduction rates were observed, demonstrating that the enzymes were anchored in the vesicles. Next, several reconstituted systems were prepared: 1) CPR.CYP1A2, 2) CPR.CYP2B4, 3) a mixture of CPR.CYP1A2 vesicles with CPR.CYP2B4 vesicles, and 4) CPR.CYP1A2.CYP2B4 in the same vesicles (ternary system). When in the ternary system, CYP2B4-mediated metabolism was significantly inhibited, and CYP1A2 activities were stimulated by the presence of the alternate P450. In contrast, P450s in separate vesicles were unable to interact. These data demonstrate that P450s must be in the same vesicles to alter metabolism. Additional evidence for a physical interaction among CPR, CYP1A2, and CYP2B4 was provided by cross-linking with bis(sulfosuccinimidyl) suberate. The results showed that after cross-linking, antibody to CYP1A2 was able to co-immunoprecipitate CYP2B4 but only when both proteins were in the same phospholipid vesicles. These results clearly demonstrate that the alterations in P450 function require both P450s to be present in the same vesicles and support a mechanism whereby P450s form a physical complex in the membrane.
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Affiliation(s)
- James R Reed
- Department of Pharmacology, Stanley S Scott Cancer Center, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA
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Subramanian M, Low M, Locuson CW, Tracy TS. CYP2D6-CYP2C9 protein-protein interactions and isoform-selective effects on substrate binding and catalysis. Drug Metab Dispos 2009; 37:1682-9. [PMID: 19448135 DOI: 10.1124/dmd.109.026500] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cytochrome P450 (P450) protein-protein interactions have been observed with various in vitro systems. It is interesting to note that these interactions seem to be isoform-dependent, with some combinations producing no effect and others producing increased or decreased catalytic activity. With some exceptions, most of the work to date has involved P450s from rabbit, rat, and other animal species, with few studies including human P450s. In the studies presented herein, the interactions of two key drug-metabolizing enzymes, CYP2C9 and CYP2D6, were analyzed in a purified, reconstituted enzyme system for changes in both substrate-binding affinity and rates of catalysis. In addition, an extensive study was conducted as to the "order of mixing" for the reconstituted enzyme system and the impact on the observations. CYP2D6 coincubation inhibited CYP2C9-mediated (S)-flurbiprofen metabolism in a protein concentration-dependent manner. V(max) values were reduced by up to 50%, but no appreciable effect on K(m) was observed. Spectral binding studies revealed a 20-fold increase in the K(S) of CYP2C9 toward (S)-flurbiprofen in the presence of CYP2D6. CYP2C9 coincubation had no effect on CYP2D6-mediated dextromethorphan O-demethylation. The order of combination of the proteins (CYP2C9, CYP2D6, and cytochrome P450 reductase) influenced the magnitude of catalysis inhibition as well as the ability of increased cytochrome P450 reductase to attenuate the change in activity. A simple model, congruent with current results and those of others, is proposed to explain oligomer formation. In summary, CYP2C9-CYP2D6 interactions can alter catalytic activity and, thus, influence in vitro-in vivo correlation predictions.
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Affiliation(s)
- Murali Subramanian
- Department of Experimental and Clinical Pharmacology, College of Pharmacy, University of Minnesota, 308 Harvard Street SE, Minneapolis, MN 55126, USA.
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50
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Davydov DR, Halpert JR. Allosteric P450 mechanisms: multiple binding sites, multiple conformers or both? Expert Opin Drug Metab Toxicol 2009; 4:1523-35. [PMID: 19040328 DOI: 10.1517/17425250802500028] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
According to the initial hypothesis on the mechanisms of cooperativity in drug-metabolizing cytochromes P450, a loose fit of a single substrate molecule in the P450 active site results in a requirement for the binding of multiple ligand molecules for efficient catalysis. Although simultaneous occupancy of the active site by multiple ligands is now well established, there is increasing evidence that the mechanistic basis of cooperativity also involves an important ligand-induced conformational transition. Moreover, recent studies demonstrate that the conformational heterogeneity of the enzyme is stabilized by ligand-dependent interactions of several P450 molecules. Application of the concept of an oligomeric allosteric enzyme to microsomal cytochromes P450 in combination with a general paradigm of multiple ligand occupancy of the active site provides an excellent explanation for complex manifestations of the atypical kinetic behavior of the enzyme.
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Affiliation(s)
- Dmitri R Davydov
- Skaggs School of Pharmacy and Pharmaceutical Sciences, UCSD, 9500 Gilman Drive, La Jolla, CA 9209, USA.
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