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Rwere F, Cartee NMP, Yang Y, Waskell L. A flexible linker of 8-amino acids between the membrane binding segment and the FMN domain of cytochrome P450 reductase is necessary for optimal activity. J Inorg Biochem 2024; 259:112667. [PMID: 39032346 PMCID: PMC11298297 DOI: 10.1016/j.jinorgbio.2024.112667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Revised: 07/11/2024] [Accepted: 07/15/2024] [Indexed: 07/23/2024]
Abstract
The diflavin NADPH-cytochrome P450 reductase (CYPOR) plays a critical role in human cytochrome P450 (CYP) activity by sequentially delivering two electrons from NADPH to CYP enzymes during catalysis. Although electron transfer to forty-eight human CYP enzymes by the FMN hydroquinone of CYPOR is well-known, the role of the linker between the NH2-terminus membrane-binding domain (MBD) and FMN domain in supporting the activity of P450 enzymes remains poorly understood. Here we demonstrate that a linker with at least eight residues is required to form a functional CYPOR-CYP2B4 complex. The linker has been shortened in two amino-acid increments from Phe44 to Ile57 using site directed mutagenesis. The ability of the deletion mutants to support cytochrome P450 2B4 (CYP2B4) catalysis and reduce ferric CYP2B4 was determined using an in vitro assay and stopped-flow spectrophotometry. Steady-state enzyme kinetics showed that shortening the linker by 8-14 amino acids inhibited (63-99%) the ability of CYPOR to support CYP2B4 activity and significantly increased the Km of CYPOR for CYP2B4. In addition, the reductase mutants decreased the rate of reduction of ferric CYP2B4 (46-95%) compared to wildtype when the linker was shortened by 8-14 residues. These results indicate that a linker with a minimum length of eight residues is necessary to enable the FMN domain of reductase to interact with CYP2B4 to form a catalytically competent complex. Our study provides evidence that the length of the MBD-FMN domain linker is a major determinant of the ability of CYPOR to support CYP catalysis and drug metabolism by P450 enzymes. PREAMBLE: This manuscript is dedicated in memory of Dr. James R. Kincaid who was the doctoral advisor to Dr. Freeborn Rwere and a longtime collaborator and friend of Dr. Lucy Waskell. Dr. James R. Kincaid was a distinguished professor of chemistry specializing in resonance Raman (rR) studies of heme proteins. He inspired Dr. Rwere (a Zimbabwean native) and three other Zimbabweans (Dr. Remigio Usai, Dr. Daniel Kaluka and Ms. Munyaradzi E. Manyumwa) to use lasers to document subtle changes occurring at heme active site of globin proteins (myoglobin and hemoglobin) and cytochrome P450 enzymes. Dr. Rwere appreciate his contributions to the development of talented Black scientists from Africa.
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Affiliation(s)
- Freeborn Rwere
- Department of Anesthesiology, University of Michigan and VAMC, 2215 Fuller Road, Ann Arbor, MI, USA; Department of Anesthesiology, Perioperative and Pain Medicine, School of Medicine, Stanford University, 3174 Porter Dr, Palo Alto, CA, USA.
| | - Naw May P Cartee
- Department of Anesthesiology, University of Michigan and VAMC, 2215 Fuller Road, Ann Arbor, MI, USA
| | - Yuting Yang
- Department of Anesthesiology, University of Michigan and VAMC, 2215 Fuller Road, Ann Arbor, MI, USA
| | - Lucy Waskell
- Department of Anesthesiology, University of Michigan and VAMC, 2215 Fuller Road, Ann Arbor, MI, USA
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Krishnarjuna B, Im SC, Ravula T, Marte J, Auchus RJ, Ramamoorthy A. Non-Ionic Inulin-Based Polymer Nanodiscs Enable Functional Reconstitution of a Redox Complex Composed of Oppositely Charged CYP450 and CPR in a Lipid Bilayer Membrane. Anal Chem 2022; 94:11908-11915. [PMID: 35977417 PMCID: PMC10851674 DOI: 10.1021/acs.analchem.2c02489] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Although polymer-based lipid nanodiscs are increasingly used in the structural studies of membrane proteins, the charge of the belt-forming polymer is a major limitation for functional reconstitution of membrane proteins possessing an opposite net charge to that of the polymer. This limitation also rules out the reconstitution of a protein-protein complex composed of oppositely charged membrane proteins. In this study, we report the first successful functional reconstitution of a membrane-bound redox complex constituting a cationic cytochrome P450 (CYP450) and an anionic cytochrome P450 reductase (CPR) in non-ionic inulin-based lipid nanodiscs. The gel-to-liquid-crystalline phase-transition temperature (Tm) of DMPC:DMPG (7:3 w/w) lipids in polymer nanodiscs was determined by differential scanning calorimetry (DSC) and 31P NMR experiments. The CYP450-CPR redox complex reconstitution in polymer nanodiscs was characterized by size-exclusion chromatography (SEC), and the electron transfer kinetics was carried out using the stopped-flow technique under anaerobic conditions. The Tm of DMPC:DMPG (7:3 w/w) in polymer nanodiscs measured from 31P NMR agrees with that obtained from DSC and was found to be higher than that for liposomes due to the decreased cooperativity of lipids present in the nanodiscs. The stopped-flow measurements revealed the CYP450-CPR redox complex reconstituted in nanodiscs to be functional, and the electron transfer kinetics was found to be temperature-dependent. Based on the successful demonstration of the use of non-ionic inulin-based polymer nanodiscs reported in this study, we expect them to be useful in studying the function and structures of a variety of membrane proteins/complexes irrespective of the charge of the molecular components. Since the polymer nanodiscs were shown to align in an externally applied magnetic field, they can also be used to measure residual dipolar couplings (RDCs) and residual quadrupolar couplings (RQCs) for various molecules ranging from small molecules to soluble proteins and nucleic acids.
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Affiliation(s)
- Bankala Krishnarjuna
- Biophysics Program, Department of Chemistry, Macromolecular Science and Engineering, Biomedical Engineering, Michigan Neuroscience Institute, The University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Sang-Choul Im
- Department of Pharmacology and Internal Medicine, Division of Metabolism, Endocrinology, & Diabetes, University of Michigan, Ann Arbor, MI 48109
| | - Thirupathi Ravula
- Biophysics Program, Department of Chemistry, Macromolecular Science and Engineering, Biomedical Engineering, Michigan Neuroscience Institute, The University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Joseph Marte
- Biophysics Program, Department of Chemistry, Macromolecular Science and Engineering, Biomedical Engineering, Michigan Neuroscience Institute, The University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Richard J. Auchus
- Department of Pharmacology and Internal Medicine, Division of Metabolism, Endocrinology, & Diabetes, University of Michigan, Ann Arbor, MI 48109
| | - Ayyalusamy Ramamoorthy
- Biophysics Program, Department of Chemistry, Macromolecular Science and Engineering, Biomedical Engineering, Michigan Neuroscience Institute, The University of Michigan, Ann Arbor, MI 48109-1055, USA
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Nolden M, Paine MJI, Nauen R. Biochemical profiling of functionally expressed CYP6P9 variants of the malaria vector Anopheles funestus with special reference to cytochrome b 5 and its role in pyrethroid and coumarin substrate metabolism. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2022; 182:105051. [PMID: 35249659 DOI: 10.1016/j.pestbp.2022.105051] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 01/24/2022] [Accepted: 01/24/2022] [Indexed: 06/14/2023]
Abstract
Cytochrome P450 monooxygenases (P450s) are well studied enzymes catalyzing the oxidative metabolism of xenobiotics in insects including mosquitoes. Their duplication and upregulation in agricultural and public health pests such as anopheline mosquitoes often leads to an enhanced metabolism of insecticides which confers resistance. In the laboratory strain Anopheles funestus FUMOZ-R the duplicated P450s CYP6P9a and CYP6P9b are highly upregulated and proven to confer pyrethroid resistance. Microsomal P450 activity is regulated by NADPH cytochrome P450 oxidoreductase (CPR) required for electron transfer, whereas the modulatory role of cytochrome b5 (CYB5) on insect P450 activity is less clear. In previous studies CYP6P9a and CYP6P9b were recombinantly expressed in tandem with An. gambiae CPR using E. coli-expression systems and CYB5 added to the reaction mix to enhance activity. However, the precise role of CYB5 on substrate turn-over when combined with CYP6P9a and CYP6P9b remains poorly investigated, thus one objective of our study was to address this knowledge gap. In contrast to the CYP6P9 variants, the expression levels of both CYB5 and CPR were not upregulated in the pyrethroid resistant FUMOZ-R strain when compared to the susceptible FANG strain, suggesting no immediate regulatory role of these genes in pyrethroid resistance in FUMOZ-R. Here, for the first time we recombinantly expressed CYP6P9a and CYP6P9b from An. funestus in a baculovirus expression system using High-5 insect cells. Co-expression of each enzyme with CPR from either An. gambiae or An. funestus did not reveal noteworthy differences in catalytic capacity. Whereas the co-expression of An. funestus CYB5 - tested at different multiplicity of infection (MOI) ratios - resulted in a significantly higher metabolization of coumarin substrates as measured by fluorescence assays. This was confirmed by Michaelis-Menten kinetics using the most active substrate, 7-benzyloxymethoxy-4-trifluoromethylcoumarin (BOMFC). We observed a similar increase in coumarin substrate turnover by adding human CYB5 to the reaction mix. Finally, we compared by UPLC-MS/MS analysis the depletion rate of deltamethrin and the formation of 4'OH-deltamethrin by recombinantly expressed CYP6P9a and CYP6P9b with and without CYB5 and detected no difference in the extent of deltamethrin metabolism. Our results suggest that co-expression (or addition) of CYB5 with CYP6P9 variants, recombinantly expressed in insect cells, can significantly enhance their metabolic capacity to oxidize coumarins, but not deltamethrin.
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Affiliation(s)
- Melanie Nolden
- Bayer AG, Crop Science Division, Alfred Nobel Str. 50, D-40789 Monheim am Rhein, Germany; Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, United Kingdom
| | - Mark J I Paine
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, United Kingdom
| | - Ralf Nauen
- Bayer AG, Crop Science Division, Alfred Nobel Str. 50, D-40789 Monheim am Rhein, Germany.
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Rwere F, Im S, Waskell L. The FMN "140s Loop" of Cytochrome P450 Reductase Controls Electron Transfer to Cytochrome P450. Int J Mol Sci 2021; 22:ijms221910625. [PMID: 34638963 PMCID: PMC8508823 DOI: 10.3390/ijms221910625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 09/25/2021] [Accepted: 09/25/2021] [Indexed: 11/29/2022] Open
Abstract
Cytochrome P450 reductase (CYPOR) provides electrons to all human microsomal cytochrome P450s (cyt P450s). The length and sequence of the “140s” FMN binding loop of CYPOR has been shown to be a key determinant of its redox potential and activity with cyt P450s. Shortening the “140s loop” by deleting glycine-141(ΔGly141) and by engineering a second mutant that mimics flavo-cytochrome P450 BM3 (ΔGly141/Glu142Asn) resulted in mutants that formed an unstable anionic semiquinone. In an attempt to understand the molecular basis of the inability of these mutants to support activity with cyt P450, we expressed, purified, and determined their ability to reduce ferric P450. Our results showed that the ΔGly141 mutant with a very mobile loop only reduced ~7% of cyt P450 with a rate similar to that of the wild type. On the other hand, the more stable loop in the ΔGly141/Glu142Asn mutant allowed for ~55% of the cyt P450 to be reduced ~60% faster than the wild type. Our results reveal that the poor activity of the ΔGly141 mutant is primarily accounted for by its markedly diminished ability to reduce ferric cyt P450. In contrast, the poor activity of the ΔGly141/Glu142Asn mutant is presumably a consequence of the altered structure and mobility of the “140s loop”.
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Affiliation(s)
- Freeborn Rwere
- Department of Anesthesiology, University of Michigan and VAMC, 2215 Fuller Road, Ann Arbor, MI 48105, USA; (S.I.); (L.W.)
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA 94305, USA
- Correspondence:
| | - Sangchoul Im
- Department of Anesthesiology, University of Michigan and VAMC, 2215 Fuller Road, Ann Arbor, MI 48105, USA; (S.I.); (L.W.)
- Department of Internal Medicine, University of Michigan and VAMC, 2215 Fuller Road, Ann Arbor, MI 48105, USA
| | - Lucy Waskell
- Department of Anesthesiology, University of Michigan and VAMC, 2215 Fuller Road, Ann Arbor, MI 48105, USA; (S.I.); (L.W.)
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5
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Kim D, Kim V, Tateishi Y, Guengerich FP. Cytochrome b 5 Binds Tightly to Several Human Cytochrome P450 Enzymes. Drug Metab Dispos 2021; 49:902-909. [PMID: 34330716 DOI: 10.1124/dmd.121.000475] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 07/13/2021] [Indexed: 01/18/2023] Open
Abstract
Numerous studies have been reported in the past 50-plus years regarding the stimulatory role of cytochrome b 5 (b 5) in some, but not all, microsomal cytochrome P450 (P450) reactions with drugs and steroids. A missing element in most of these studies has been a sensitive and accurate measure of binding affinities of b 5 with P450s. In the course of work with P450 17A1, we developed a fluorescent derivative of a human b 5 site-directed mutant, Alexa 488-T70C-b 5, that could be used in binding assays at sub-μM concentrations. Alexa 488-T70C-b 5 bound to human P450s 1A2, 2B6, 2C8, 2C9, 2E1, 2S1, 4A11, 3A4, and 17A1, with estimated K d values ranging from 2.5 to 61 nM. Only weak binding was detected with P450 2D6, and no fluorescence attenuation was observed with P450 2A6. All of the P450s that bound b 5 have some reported activity stimulation except for P450 2S1. The affinity of P450 3A4 for b 5 was decreased somewhat by the presence of a substrate or inhibitor. The fluorescence of a P450 3A4•Alexa 488-T70C-b 5 complex was partially restored by titration with NADPH-P450 reductase (POR) (K d,apparent 89 nM), suggesting the existence of a ternary P450 3A4-b 5-POR complex, as observed previously with P450 17A1. Gel filtration evidence was also obtained for this ternary complex with P450 3A4. Overall, the results indicated that the affinity of b 5 for many P450s is very high, and that ternary P450-b 5-POR complexes are relevant in P450 3A4 reactions as opposed to a shuttle mechanism. SIGNIFICANCE STATEMENT: High-affinity binding of cytochrome b 5 (b 5) (K d < 100 nM) was observed with many drug-metabolizing cytochrome P450 (P450) enzymes. There is some correlation of binding with reported stimulation, with several exceptions. Evidence is provided for a ternary P450 3A4-b 5-NADPH-P450 reductase complex.
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Affiliation(s)
- Donghak Kim
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146 (D.K., Y.T., F.P.G.), and Department of Biological Sciences, Konkuk University, Seoul, Republic of Korea (D.K., V.K.)
| | - Vitchan Kim
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146 (D.K., Y.T., F.P.G.), and Department of Biological Sciences, Konkuk University, Seoul, Republic of Korea (D.K., V.K.)
| | - Yasuhiro Tateishi
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146 (D.K., Y.T., F.P.G.), and Department of Biological Sciences, Konkuk University, Seoul, Republic of Korea (D.K., V.K.)
| | - F Peter Guengerich
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146 (D.K., Y.T., F.P.G.), and Department of Biological Sciences, Konkuk University, Seoul, Republic of Korea (D.K., V.K.)
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6
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Liu Y, Denisov IG, Sligar SG, Kincaid JR. Substrate-Specific Allosteric Effects on the Enhancement of CYP17A1 Lyase Efficiency by Cytochrome b5. J Am Chem Soc 2021; 143:3729-3733. [PMID: 33656879 DOI: 10.1021/jacs.1c00581] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
CYP17A1 is an essential human steroidogenic enzyme, which catalyzes two sequential reactions leading to the formation of androstenedione from progesterone and dehydroepiandrosterone from pregnenolone. The second reaction is the C17-C20 bond scission, which is strongly dependent on the presence of cytochrome b5 and displays a heretofore unexplained more pronounced acceleration when 17OH-progesteone (17OH-PROG) is a substrate. The origin of the stimulating effect of cytochrome b5 on C-C bond scission catalyzed by CYP17A1 is still debated as mostly due to either the acceleration of the electron transfer to the P450 oxy complex or allosteric effects of cytochrome b5 favoring active site conformations that promote lyase activity. Using resonance Raman spectroscopy, we compared the effect of Mn-substituted cytochrome b5 (Mn-Cytb5) on the oxy complex of CYP17A1 with both proteins co-incorporated in lipid nanodiscs. For CYP17A1 with 17OH-PROG, a characteristic shift of the Fe-O mode is observed in the presence of Mn-b5, indicating reorientation of a hydrogen bond between the 17OH group of the substrate from the terminal to the proximal oxygen atom of the Fe-O-O moiety, a configuration favorable for the lyase catalysis. For 17OH-pregnenolone, no such shift is observed, the favorable H-bonding orientation being present even without Mn-Cytb5. These new data provide a precise allosteric interpretation for the more pronounced acceleration seen for the 17OH-PROG substrate.
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Affiliation(s)
- Yilin Liu
- Department of Chemistry, Marquette University, 1414W Clybourn Street, Milwaukee, Wisconsin 53233, United States
| | | | | | - James R Kincaid
- Department of Chemistry, Marquette University, 1414W Clybourn Street, Milwaukee, Wisconsin 53233, United States
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7
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He Z, Deng H, Wang Q, Li Y, Liang X, Liu D, Wu Y. Electrochemical and spectroscopic characteristics of cytochrome P450 55A3 and its interaction with nitric oxide. Int J Biol Macromol 2020; 167:1406-1413. [PMID: 33202279 DOI: 10.1016/j.ijbiomac.2020.11.094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 08/17/2020] [Accepted: 11/12/2020] [Indexed: 11/30/2022]
Abstract
Cytochrome P450 55A3 (CYP55A3) is an enzyme with the catalytic activity of nitric oxide (NO) to nitrous oxide using NADH or NADPH as the electron donor. Herein CYP55A3 has been expressed in E. coli and purified by His-tag columns. The electrochemical and spectroscopic characteristic of CYP55A3 and its interaction with NO has been studied. The direct electrochemistry of Fe3+/Fe2+ redox peaks in CYP55A3 was realized on the pyrolitic graphite electrode with the redox potential of -475 mV in pH 7.0 phosphate buffer. With the addition of NO a ferric nitroxyl complex (Fe3+-NO) formed with a new reduction peak at -0.78 V. The reduction peak current increased with the concentration of NO and showed typical Michaelis-Menten kinetic characteristics with the apparent Michaelis constant Kmapp 9.78 μM. The binding constant K calculated to be 3.93 × 104 M by UV-vis method. The fluorescence emission spectra of iron porphyrin in CYP55A3 showed with the peak wavelength 633 nm, and its fluorescence intensity increased after binding with NO. The fluorescence analysis demonstrated that NADH can relay electrons to iron porphyrin and reduce NO. The reductive product of NO released and the iron porphyrin in CYP55A3 turned back to the original form.
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Affiliation(s)
- Zheng He
- College of Life Science, South Central University for Nationalities, Wuhan 430074, PR China
| | - Huan Deng
- College of Life Science, South Central University for Nationalities, Wuhan 430074, PR China
| | - Qiang Wang
- College of Pharmacy, South Central University for Nationalities, Wuhan 430074, PR China
| | - Yong Li
- College of Life Science, South Central University for Nationalities, Wuhan 430074, PR China
| | - Xiaosheng Liang
- College of Life Science, South Central University for Nationalities, Wuhan 430074, PR China
| | - Deli Liu
- College of Life Science, Central China Normal University, Wuhan 430079, PR China
| | - Yunhua Wu
- College of Life Science, South Central University for Nationalities, Wuhan 430074, PR China.
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8
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Orr TJ, Kitanovic S, Schramm KM, Skopec MM, Wilderman PR, Halpert JR, Dearing MD. Strategies in herbivory by mammals revisited: The role of liver metabolism in a juniper specialist (Neotoma stephensi) and a generalist (Neotoma albigula). Mol Ecol 2020; 29:1674-1683. [PMID: 32246507 DOI: 10.1111/mec.15431] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 03/03/2020] [Accepted: 03/11/2020] [Indexed: 10/24/2022]
Abstract
Although herbivory is widespread among mammals, few species have adopted a strategy of dietary specialization. Feeding on a single plant species often exposes herbivores to high doses of plant secondary metabolites (PSMs), which may exceed the animal's detoxification capacities. Theory predicts that specialists will have unique detoxification mechanisms to process high levels of dietary toxins. To evaluate this hypothesis, we compared liver microsomal metabolism of a juniper specialist, Neotoma stephensi (diet >85% juniper), to a generalist, N. albigula (diet ≤30% juniper). Specifically, we quantified the concentration of a key detoxification enzyme, cytochrome P450 2B (CYP2B) in liver microsomes, and the metabolism of α-pinene, the most abundant terpene in the juniper species consumed by the specialist woodrat. In both species, a 30% juniper diet increased the total CYP2B concentration (2-3×) in microsomes and microsomal α-pinene metabolism rates (4-fold). In N. stephensi, higher levels of dietary juniper (60% and 100%) further induced CYP2B and increased metabolism rates of α-pinene. Although no species-specific differences in metabolism rates were observed at 30% dietary juniper, total microsomal CYP2B concentration was 1.7× higher in N. stephensi than in N. albigula (p < .01), suggesting N. stephensi produces one or more variant of CYP2B that is less efficient at processing α-pinene. In N. stephensi, the rates of α-pinene metabolism increased with dietary juniper and were positively correlated with CYP2B concentration. The ability of N. stephensi to elevate CYP2B concentration and rate of α-pinene metabolism with increasing levels of juniper in the diet may facilitate juniper specialization in this species.
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Affiliation(s)
- Teri J Orr
- School of Biological Sciences, University of Utah, Salt Lake City, UT, USA
| | - Smiljka Kitanovic
- School of Biological Sciences, University of Utah, Salt Lake City, UT, USA
| | - Katharina M Schramm
- School of Biological Sciences, University of Utah, Salt Lake City, UT, USA.,Department of Botany, Weber State University, Ogden, UT, USA
| | | | | | - James R Halpert
- School of Pharmacy, University of Connecticut, Storrs, CT, USA
| | - M Denise Dearing
- School of Biological Sciences, University of Utah, Salt Lake City, UT, USA
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9
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Gentry KA, Anantharamaiah GM, Ramamoorthy A. Probing protein-protein and protein-substrate interactions in the dynamic membrane-associated ternary complex of cytochromes P450, b 5, and reductase. Chem Commun (Camb) 2019; 55:13422-13425. [PMID: 31638629 PMCID: PMC6879317 DOI: 10.1039/c9cc05904k] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cytochrome P450 (cytP450) interacts with two redox partners, cytP450 reductase and cytochrome-b5, to metabolize substrates. Using NMR, we reveal changes in the dynamic interplay when all three proteins are incorporated into lipid nanodiscs in the absence and presence of substrates.
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Affiliation(s)
- Katherine A Gentry
- Biophysics and Department of Chemistry, Biomedical Engineering, Macromolecular Science and Engineering, University of Michigan, Ann Arbor, MI 48109-1055, USA.
| | - G M Anantharamaiah
- Department of Medicine, UAB Medical Center, Birmingham, Alabama 35294, USA
| | - Ayyalusamy Ramamoorthy
- Biophysics and Department of Chemistry, Biomedical Engineering, Macromolecular Science and Engineering, University of Michigan, Ann Arbor, MI 48109-1055, USA.
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10
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Jiang Z, Lin C, Liu H, Feng J, Zheng Z, Cai S. Specific biological responses following dextran-coated ultra-small superparamagnetic particles of iron oxides administration. Nanomedicine (Lond) 2019; 14:1371-1386. [PMID: 31215328 DOI: 10.2217/nnm-2018-0433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Aim: The potential bio-related risks of dextran-coated ultra-small superparamagnetic particles of iron oxides (D-USPIO) were assessed. Materials & methods: Metabolic responses of D-USPIO in BALB/C mice were obtained using 1H-NMR-based metabolomic strategy combined with the traditional biochemical assay. Results: The metabolomic analyses of biological fluids (plasma and urine) and organs (liver, kidney and spleen) indicated that the disturbance, impairment and recovery of the physiological functions were related to the metabolic response to D-USPIO. The correlations between the biofluids and tissue metabolomes described the specific metabolic information of D-USPIO on their in vivo transportation, absorption, biodistribution and excretion. Conclusion: Metabolomic analysis provides preliminary validation for the use of D-USPIO in clinical medicine, and the results help to understand the potential adverse effects of the similar bio-nanomaterials further serve to their synthesis optimization and biocompatibility improvement.
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Affiliation(s)
- Zhiming Jiang
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma & Magnetic Resonance, Xiamen University, Xiamen 361005, PR China
| | - Chenghong Lin
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma & Magnetic Resonance, Xiamen University, Xiamen 361005, PR China
| | - Huili Liu
- State Key Laboratory of Magnetic Resonance & Atomic & Molecular Physics, Wuhan Center for Magnetic Resonance, Wuhan Institute of Physics & Mathematics, Chinese Academy of Sciences, Wuhan 430071, PR China
| | - Jianghua Feng
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma & Magnetic Resonance, Xiamen University, Xiamen 361005, PR China
| | - Zhenyao Zheng
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma & Magnetic Resonance, Xiamen University, Xiamen 361005, PR China
| | - Shuhui Cai
- Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma & Magnetic Resonance, Xiamen University, Xiamen 361005, PR China
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11
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Luan H, Niu H, Luo J, Zhi H. Soybean Cytochrome b5 Is a Restriction Factor for Soybean Mosaic Virus. Viruses 2019; 11:E546. [PMID: 31212671 PMCID: PMC6631803 DOI: 10.3390/v11060546] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 06/06/2019] [Accepted: 06/07/2019] [Indexed: 12/25/2022] Open
Abstract
Soybean mosaic virus (SMV) is one of the most destructive viral diseases in soybeans (Glycine max). In this study, an interaction between the SMV P3 protein and cytochrome b5 was detected by yeast two-hybrid assay, and bimolecular fluorescence complementation assay showed that the interaction took place at the cell periphery. Further, the interaction was confirmed by co-immunoprecipitation analysis. Quantitative real-time polymerase chain reaction analysis revealed that GmCYB5 gene was differentially expressed in resistant and susceptible soybean plants after inoculation with SMV-SC15 strain. To test the involvement of this gene in SMV resistance, the GmCYB5 was silenced using a bean pod mottle virus (BPMV)-based vector construct. Results showed that GmCYB5-1 was 83% and 99% downregulated in susceptible (NN1138-2) and resistant (RN-9) cultivars, respectively, compared to the empty vector-treated plants. Silencing of GmCYB5 gene promotes SMV replication in soybean plants. Our results suggest that during SMV infection, the host CYB5 protein targets P3 protein to inhibit its proliferation. Taken together, these results suggest that CYB5 is an important factor in SMV infection and replication in soybeans, which could help soybean breeders develop SMV resistant soybean cultivars.
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Affiliation(s)
- Hexiang Luan
- National Center for Soybean Improvement, Nanjing Agricultural University, Nanjing 210095, China.
| | - Haopeng Niu
- National Center for Soybean Improvement, Nanjing Agricultural University, Nanjing 210095, China.
| | - Jinyan Luo
- National Center for Soybean Improvement, Nanjing Agricultural University, Nanjing 210095, China.
| | - Haijian Zhi
- National Center for Soybean Improvement, Nanjing Agricultural University, Nanjing 210095, China.
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12
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Frankincense essential oil suppresses melanoma cancer through down regulation of Bcl-2/Bax cascade signaling and ameliorates heptotoxicity via phase I and II drug metabolizing enzymes. Oncotarget 2019; 10:3472-3490. [PMID: 31191820 PMCID: PMC6544398 DOI: 10.18632/oncotarget.26930] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 04/03/2019] [Indexed: 12/19/2022] Open
Abstract
Melanoma is a deadly form of malignancy and according to the World Health Organization 132,000 new cases of melanoma are diagnosed worldwide each year. Surgical resection and chemo/drug treatments opted for early and late stage of melanoma respectively, however detrimental post surgical and chemotherapy consequences are inevitable. Noticeably melanoma drug treatments are associated with liver injuries such as hepatitis and cholestasis which are very common. Alleviation of these clinical manifestations with better treatment options would enhance prognosis status and patients survival. Natural products which induce cytotoxicity with minimum side effects are of interest to achieve high therapeutic efficiency. In this study we investigated anti-melanoma and hepatoprotective activities of frankincense essential oil (FEO) in both in vitro and in vivo models. Pretreatment with FEO induce a significant (p < 0.05) dose-dependent reduction in the cell viability of mouse (B16-F10) and human melanoma (FM94) but not in the normal human epithelial melanocytes (HNEM). Immunoblot analysis showed that FEO induces down regulation of Bcl-2 and up regulation of BAX in B16-F10 cells whereas in FM94 cells FEO induced dose-dependent cleavage of caspase 3, caspase 9 and PARP. Furthermore, FEO (10 μg/ml) treatment down regulated MCL1 in a time-dependent manner in FM94 cells. In vivo toxicity analysis reveals that weekly single dose of FEO (1200 mg/kg body weight) did not elicit detrimental effect on body weight during four weeks of experimental period. Histology of tissue sections also indicated that there were no observable histopathologic differences in the brain, heart, liver, and kidney compare to control groups. FEO (300 and 600 mg/kg body weight) treatments significantly reduced the tumor burden in C57BL/6 mice melanoma model. Acetaminophen (750 mg/kg body weight) was used to induce hepatic injury in Swiss albino mice. Pre treatment with FEO (250 and 500 mg/kg body weight) for seven days retained hematology (complete blood count), biochemical parameters (AST, ALT, ALK, total bilirubin, total protein, glucose, albumin/globulin ratio, cholesterol and triglyceride), and the level of phase I and II drug metabolizing enzymes (cytochrome P450, cytochromeb5, glutathione-S-transferase) which were obstructed by the administration of acetaminophen. Further liver histology showed that FEO treatments reversed the damages (central vein dilation, hemorrhage, and nuclei condensation) caused by acetaminophen. In conclusion, FEO elicited marked anti-melanoma in both in vitro and in vivo with a significant heptoprotection.
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13
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Abstract
Enzymes are complex biological catalysts and are critical to life. Most oxidations of chemicals are catalyzed by cytochrome P450 (P450, CYP) enzymes, which generally utilize mixed-function oxidase stoichiometry, utilizing pyridine nucleotides as electron donors: NAD(P)H + O2 + R → NAD(P)+ + RO + H2O (where R is a carbon substrate and RO is an oxidized product). The catalysis of oxidations is largely understood in the context of the heme iron-oxygen complex generally referred to as Compound I, formally FeO3+, whose basis was in peroxidase chemistry. Many X-ray crystal structures of P450s are now available (≥ 822 structures from ≥146 different P450s) and have helped in understanding catalytic specificity. In addition to hydroxylations, P450s catalyze more complex oxidations, including C-C bond formation and cleavage. Enzymes derived from P450s by directed evolution can even catalyze more unusual reactions, e.g. cyclopropanation. Current P450 questions under investigation include the potential role of the intermediate Compound 0 (formally FeIII-O2 -) in catalysis of some reactions, the roles of high- and low-spin forms of Compound I, the mechanism of desaturation, the roles of open and closed structures of P450s in catalysis, the extent of processivity in multi-step oxidations, and the role of the accessory protein cytochrome b 5. More global questions include exactly how structure drives function, prediction of catalysis, and roles of multiple protein conformations.
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Affiliation(s)
- F. Peter Guengerich
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, United States
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14
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Gentry KA, Zhang M, Im SC, Waskell L, Ramamoorthy A. Substrate mediated redox partner selectivity of cytochrome P450. Chem Commun (Camb) 2018; 54:5780-5783. [PMID: 29781479 DOI: 10.1039/c8cc02525h] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Investigating the interplay between cytochrome-P450 and its redox partners (CPR and cytochrome-b5) is vital for understanding the metabolism of most hydrophobic drugs. Dynamic structural interactions with the ternary complex, with and without substrates, captured by NMR reveal a gating mechanism for redox partners to promote P450 function.
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Affiliation(s)
- Katherine A Gentry
- Biophysics and Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA.
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15
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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: 20] [Impact Index Per Article: 3.3] [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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16
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Zhang H, Yokom AL, Cheng S, Su M, Hollenberg PF, Southworth DR, Osawa Y. The full-length cytochrome P450 enzyme CYP102A1 dimerizes at its reductase domains and has flexible heme domains for efficient catalysis. J Biol Chem 2018; 293:7727-7736. [PMID: 29618513 DOI: 10.1074/jbc.ra117.000600] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 03/28/2018] [Indexed: 11/06/2022] Open
Abstract
The cytochrome P450 enzyme CYP102A1 from Bacillus megaterium is a highly efficient hydroxylase of fatty acids, and there is a significant interest in using CYP102A1 for biotechnological applications. Here, we used size-exclusion chromatography-multiangle light scattering (SEC-MALS) analysis and negative-stain EM to investigate the molecular architecture of CYP102A1. The SEC-MALS analysis yielded a homogeneous peak with an average molecular mass of 235 ± 5 kDa, consistent with homodimeric CYP102A1. The negative-stain EM of dimeric CYP102A1 revealed four distinct lobes, representing the two heme and two reductase domains. Two of the lobes were in close contact, whereas the other two were often observed apart and at the ends of a U-shaped configuration. The overall dimension of the dimer was ∼130 Å. To determine the identity of the lobes, we FLAG-tagged the N or C terminus of CYP102A1 to visualize additional densities in EM and found that anti-FLAG Fab could bind only the N-tagged P450. Single-particle analysis of this anti-Flag Fab-CYP102A1 complex revealed additional density in the N-terminally tagged heme domains, indicating that the heme domains appear flexible, whereas the reductase domains remain tightly associated. The effects of truncation on CYP102A1 dimerization, identification of cross-linked sites by peptide mapping, and molecular modeling results all were consistent with the dimerization of the reductase domain. We conclude that functional CYP102A1 is a compact globular protein dimerized at its reductase domains, with its heme domains exhibiting multiple conformations that likely contribute to the highly efficient catalysis of CYP102A1.
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Affiliation(s)
| | | | - Shen Cheng
- From the Departments of Pharmacology and
| | - Min Su
- the Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109
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17
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Bhatt MR, Khatri Y, Rodgers RJ, Martin LL. Role of cytochrome b5 in the modulation of the enzymatic activities of cytochrome P450 17α-hydroxylase/17,20-lyase (P450 17A1). J Steroid Biochem Mol Biol 2017; 170:2-18. [PMID: 26976652 DOI: 10.1016/j.jsbmb.2016.02.033] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 02/25/2016] [Accepted: 02/27/2016] [Indexed: 12/13/2022]
Abstract
Cytochrome b5 (cyt b5) is a small hemoprotein that plays a significant role in the modulation of activities of an important steroidogenic enzyme, cytochrome P450 17α-hydroxylase/17,20-lyase (P450 17A1, CYP17A1). Located in the zona fasciculata and zona reticularis of the adrenal cortex and in the gonads, P450 17A1 catalyzes two different reactions in the steroidogenic pathway; the 17α-hydroxylation and 17,20-lyase, in the endoplasmic reticulum of these respective tissues. The activities of P450 17A1 are regulated by cyt b5 that enhances the 17,20-lyase reaction by promoting the coupling of P450 17A1 and cytochrome P450 reductase (CPR), allosterically. Cyt b5 can also act as an electron donor to enhance the 16-ene-synthase activity of human P450 17A1. In this review, we discuss the many roles of cyt b5 and focus on the modulation of CYP17A1 activities by cyt b5 and the mechanisms involved.
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Affiliation(s)
- Megh Raj Bhatt
- Everest Biotech Pvt. Ltd., Khumaltar, Lalitpur, P.O. Box 21608, Kathmandu 44600, Nepal
| | - Yogan Khatri
- Institute of Biochemistry, Saarland University, 66123 Saarbrücken, Germany
| | - Raymond J Rodgers
- School of Medicine, Robinson Research Institute, University of Adelaide, Adelaide SA 5005, Australia
| | - Lisandra L Martin
- School of Chemistry, Monash University, Clayton, 3800, Victoria, Australia.
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18
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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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19
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Yadav R, Petrunak EM, Estrada DF, Scott EE. Structural insights into the function of steroidogenic cytochrome P450 17A1. Mol Cell Endocrinol 2017; 441:68-75. [PMID: 27566228 PMCID: PMC5235955 DOI: 10.1016/j.mce.2016.08.035] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 08/19/2016] [Accepted: 08/22/2016] [Indexed: 12/12/2022]
Abstract
Cytochrome P450 17A1 (CYP17A1) operates at the core of human steroidogenesis, directing precursors into mineralocorticoids, glucocorticoids, or sex steroids. Although the 17α-hydroxylase and 17,20-lyase activities of this dual function enzyme have been investigated extensively, until recently no CYP17A1 structures were available to inform our understanding. Structures of CYP17A1 with a range of steroidal inhibitors and substrates are now available. This review relates functional knowledge of this enzyme to structural features defining the selective differentiation between its various substrates. While both hydroxylase and lyase substrates have similar orientations with respect to the heme, subtle differences in hydrogen bonding between CYP17A1 and the C3 substituent at the opposite end of ligands appear to correlate with differential substrate utilization and product formation. Complementary structural information from solution NMR supports cytochrome b5 allosteric modulation of the lyase reaction, implicating regions involved in ligand access to the otherwise buried active site.
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Affiliation(s)
- Rahul Yadav
- Department of Medicinal Chemistry, 1251 Wescoe Hall Dr., The University of Kansas, Lawrence, KS 66045, USA
| | - Elyse M Petrunak
- Department of Medicinal Chemistry, 1251 Wescoe Hall Dr., The University of Kansas, Lawrence, KS 66045, USA
| | - D Fernando Estrada
- Department of Medicinal Chemistry, 1251 Wescoe Hall Dr., The University of Kansas, Lawrence, KS 66045, USA
| | - Emily E Scott
- Department of Medicinal Chemistry, 1251 Wescoe Hall Dr., The University of Kansas, Lawrence, KS 66045, USA.
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20
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Pearl NM, Wilcoxen J, Im S, Kunz R, Darty J, Britt RD, Ragsdale SW, Waskell L. Protonation of the Hydroperoxo Intermediate of Cytochrome P450 2B4 Is Slower in the Presence of Cytochrome P450 Reductase Than in the Presence of Cytochrome b5. Biochemistry 2016; 55:6558-6567. [PMID: 27797496 DOI: 10.1021/acs.biochem.6b00996] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Microsomal cytochromes P450 (P450) require two electrons and two protons for the oxidation of substrates. Although the two electrons can be provided by cytochrome P450 reductase, the second electron can also be donated by cytochrome b5 (b5). The steady-state activity of P450 2B4 is increased up to 10-fold by b5. To improve our understanding of the molecular basis of the stimulatory effect of b5 and to test the hypothesis that b5 stimulates catalysis by more rapid protonation of the anionic ferric hydroperoxo heme intermediate of P450 (Fe3+OOH)- and subsequent formation of the active oxidizing species (Fe+4═O POR•+), we have freeze-quenched the reaction mixture during a single turnover following reduction of oxyferrous P450 2B4 by each of its redox partners, b5 and P450 reductase. The electron paramagnetic resonance spectra of the freeze-quenched reaction mixtures lacked evidence of a hydroperoxo intermediate when b5 was the reductant presumably because hydroperoxo protonation and catalysis occurred within the dead time of the instrument. However, when P450 reductase was the reductant, a hydroperoxo P450 intermediate was observed. The effect of b5 on the enzymatic efficiency in D2O and the kinetic solvent isotope effect under steady-state conditions are both consistent with the ability of b5 to promote rapid protonation of the hydroperoxo species and more efficient catalysis. In summary, by binding to the proximal surface of P450, b5 stimulates the activity of P450 2B4 by enhancing the rate of protonation of the hydroperoxo intermediate and formation of Compound I, the active oxidizing species, which allows less time for side product formation.
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Affiliation(s)
- Naw May Pearl
- Department of Anesthesiology, University of Michigan Medical School , Ann Arbor, Michigan 48109-0112, United States
| | - Jarett Wilcoxen
- Department of Chemistry, University of California, Davis , Davis, California 95616, United States
| | - Sangchoul Im
- Department of Anesthesiology, University of Michigan Medical School , Ann Arbor, Michigan 48109-0112, United States
| | - Ryan Kunz
- Department of Biological Chemistry, University of Michigan Medical School , Ann Arbor, Michigan 48109-0600, United States
| | - Joseph Darty
- Department of Biological Chemistry, University of Michigan Medical School , Ann Arbor, Michigan 48109-0600, United States
| | - R David Britt
- Department of Chemistry, University of California, Davis , Davis, California 95616, United States
| | - Stephen W Ragsdale
- Department of Biological Chemistry, University of Michigan Medical School , Ann Arbor, Michigan 48109-0600, United States
| | - Lucy Waskell
- Department of Anesthesiology, University of Michigan Medical School , Ann Arbor, Michigan 48109-0112, United States
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21
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Scott EE, Wolf CR, Otyepka M, Humphreys SC, Reed JR, Henderson CJ, McLaughlin LA, Paloncýová M, Navrátilová V, Berka K, Anzenbacher P, Dahal UP, Barnaba C, Brozik JA, Jones JP, Estrada DF, Laurence JS, Park JW, Backes WL. The Role of Protein-Protein and Protein-Membrane Interactions on P450 Function. Drug Metab Dispos 2016; 44:576-90. [PMID: 26851242 PMCID: PMC4810767 DOI: 10.1124/dmd.115.068569] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Accepted: 02/03/2016] [Indexed: 11/22/2022] Open
Abstract
This symposium summary, sponsored by the ASPET, was held at Experimental Biology 2015 on March 29, 2015, in Boston, Massachusetts. The symposium focused on: 1) the interactions of cytochrome P450s (P450s) with their redox partners; and 2) the role of the lipid membrane in their orientation and stabilization. Two presentations discussed the interactions of P450s with NADPH-P450 reductase (CPR) and cytochrome b5. First, solution nuclear magnetic resonance was used to compare the protein interactions that facilitated either the hydroxylase or lyase activities of CYP17A1. The lyase interaction was stimulated by the presence of b5 and 17α-hydroxypregnenolone, whereas the hydroxylase reaction was predominant in the absence of b5. The role of b5 was also shown in vivo by selective hepatic knockout of b5 from mice expressing CYP3A4 and CYP2D6; the lack of b5 caused a decrease in the clearance of several substrates. The role of the membrane on P450 orientation was examined using computational methods, showing that the proximal region of the P450 molecule faced the aqueous phase. The distal region, containing the substrate-access channel, was associated with the membrane. The interaction of NADPH-P450 reductase (CPR) with the membrane was also described, showing the ability of CPR to "helicopter" above the membrane. Finally, the endoplasmic reticulum (ER) was shown to be heterogeneous, having ordered membrane regions containing cholesterol and more disordered regions. Interestingly, two closely related P450s, CYP1A1 and CYP1A2, resided in different regions of the ER. The structural characteristics of their localization were examined. These studies emphasize the importance of P450 protein organization to their function.
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Affiliation(s)
- Emily E Scott
- Departments of Medicinal Chemistry and Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas (D.F.E, J.S.L., E.E.S.); Division of Cancer Research, School of Medicine, University of Dundee, Ninewells Hospital, Dundee, United Kingdom (C.R.W., C.J.H., L.A.M.); Regional Center of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science (M.O., M.P., V.N., K.B.) and Department of Pharmacology, Faculty of Medicine and Dentistry (P.A.), Palacký University, Olomouc, Czech Republic; Department of Chemistry, Washington State University, Pullman, Washington (S.C.H., U.P.D., C.B., J.A.B., J.P.J.); and Department of Pharmacology and Experimental Therapeutics, and the Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, New Orleans, Louisiana (J.R.R., J.W.P., W.L.B.)
| | - C Roland Wolf
- Departments of Medicinal Chemistry and Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas (D.F.E, J.S.L., E.E.S.); Division of Cancer Research, School of Medicine, University of Dundee, Ninewells Hospital, Dundee, United Kingdom (C.R.W., C.J.H., L.A.M.); Regional Center of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science (M.O., M.P., V.N., K.B.) and Department of Pharmacology, Faculty of Medicine and Dentistry (P.A.), Palacký University, Olomouc, Czech Republic; Department of Chemistry, Washington State University, Pullman, Washington (S.C.H., U.P.D., C.B., J.A.B., J.P.J.); and Department of Pharmacology and Experimental Therapeutics, and the Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, New Orleans, Louisiana (J.R.R., J.W.P., W.L.B.)
| | - Michal Otyepka
- Departments of Medicinal Chemistry and Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas (D.F.E, J.S.L., E.E.S.); Division of Cancer Research, School of Medicine, University of Dundee, Ninewells Hospital, Dundee, United Kingdom (C.R.W., C.J.H., L.A.M.); Regional Center of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science (M.O., M.P., V.N., K.B.) and Department of Pharmacology, Faculty of Medicine and Dentistry (P.A.), Palacký University, Olomouc, Czech Republic; Department of Chemistry, Washington State University, Pullman, Washington (S.C.H., U.P.D., C.B., J.A.B., J.P.J.); and Department of Pharmacology and Experimental Therapeutics, and the Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, New Orleans, Louisiana (J.R.R., J.W.P., W.L.B.)
| | - Sara C Humphreys
- Departments of Medicinal Chemistry and Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas (D.F.E, J.S.L., E.E.S.); Division of Cancer Research, School of Medicine, University of Dundee, Ninewells Hospital, Dundee, United Kingdom (C.R.W., C.J.H., L.A.M.); Regional Center of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science (M.O., M.P., V.N., K.B.) and Department of Pharmacology, Faculty of Medicine and Dentistry (P.A.), Palacký University, Olomouc, Czech Republic; Department of Chemistry, Washington State University, Pullman, Washington (S.C.H., U.P.D., C.B., J.A.B., J.P.J.); and Department of Pharmacology and Experimental Therapeutics, and the Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, New Orleans, Louisiana (J.R.R., J.W.P., W.L.B.)
| | - James R Reed
- Departments of Medicinal Chemistry and Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas (D.F.E, J.S.L., E.E.S.); Division of Cancer Research, School of Medicine, University of Dundee, Ninewells Hospital, Dundee, United Kingdom (C.R.W., C.J.H., L.A.M.); Regional Center of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science (M.O., M.P., V.N., K.B.) and Department of Pharmacology, Faculty of Medicine and Dentistry (P.A.), Palacký University, Olomouc, Czech Republic; Department of Chemistry, Washington State University, Pullman, Washington (S.C.H., U.P.D., C.B., J.A.B., J.P.J.); and Department of Pharmacology and Experimental Therapeutics, and the Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, New Orleans, Louisiana (J.R.R., J.W.P., W.L.B.)
| | - Colin J Henderson
- Departments of Medicinal Chemistry and Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas (D.F.E, J.S.L., E.E.S.); Division of Cancer Research, School of Medicine, University of Dundee, Ninewells Hospital, Dundee, United Kingdom (C.R.W., C.J.H., L.A.M.); Regional Center of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science (M.O., M.P., V.N., K.B.) and Department of Pharmacology, Faculty of Medicine and Dentistry (P.A.), Palacký University, Olomouc, Czech Republic; Department of Chemistry, Washington State University, Pullman, Washington (S.C.H., U.P.D., C.B., J.A.B., J.P.J.); and Department of Pharmacology and Experimental Therapeutics, and the Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, New Orleans, Louisiana (J.R.R., J.W.P., W.L.B.)
| | - Lesley A McLaughlin
- Departments of Medicinal Chemistry and Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas (D.F.E, J.S.L., E.E.S.); Division of Cancer Research, School of Medicine, University of Dundee, Ninewells Hospital, Dundee, United Kingdom (C.R.W., C.J.H., L.A.M.); Regional Center of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science (M.O., M.P., V.N., K.B.) and Department of Pharmacology, Faculty of Medicine and Dentistry (P.A.), Palacký University, Olomouc, Czech Republic; Department of Chemistry, Washington State University, Pullman, Washington (S.C.H., U.P.D., C.B., J.A.B., J.P.J.); and Department of Pharmacology and Experimental Therapeutics, and the Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, New Orleans, Louisiana (J.R.R., J.W.P., W.L.B.)
| | - Markéta Paloncýová
- Departments of Medicinal Chemistry and Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas (D.F.E, J.S.L., E.E.S.); Division of Cancer Research, School of Medicine, University of Dundee, Ninewells Hospital, Dundee, United Kingdom (C.R.W., C.J.H., L.A.M.); Regional Center of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science (M.O., M.P., V.N., K.B.) and Department of Pharmacology, Faculty of Medicine and Dentistry (P.A.), Palacký University, Olomouc, Czech Republic; Department of Chemistry, Washington State University, Pullman, Washington (S.C.H., U.P.D., C.B., J.A.B., J.P.J.); and Department of Pharmacology and Experimental Therapeutics, and the Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, New Orleans, Louisiana (J.R.R., J.W.P., W.L.B.)
| | - Veronika Navrátilová
- Departments of Medicinal Chemistry and Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas (D.F.E, J.S.L., E.E.S.); Division of Cancer Research, School of Medicine, University of Dundee, Ninewells Hospital, Dundee, United Kingdom (C.R.W., C.J.H., L.A.M.); Regional Center of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science (M.O., M.P., V.N., K.B.) and Department of Pharmacology, Faculty of Medicine and Dentistry (P.A.), Palacký University, Olomouc, Czech Republic; Department of Chemistry, Washington State University, Pullman, Washington (S.C.H., U.P.D., C.B., J.A.B., J.P.J.); and Department of Pharmacology and Experimental Therapeutics, and the Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, New Orleans, Louisiana (J.R.R., J.W.P., W.L.B.)
| | - Karel Berka
- Departments of Medicinal Chemistry and Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas (D.F.E, J.S.L., E.E.S.); Division of Cancer Research, School of Medicine, University of Dundee, Ninewells Hospital, Dundee, United Kingdom (C.R.W., C.J.H., L.A.M.); Regional Center of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science (M.O., M.P., V.N., K.B.) and Department of Pharmacology, Faculty of Medicine and Dentistry (P.A.), Palacký University, Olomouc, Czech Republic; Department of Chemistry, Washington State University, Pullman, Washington (S.C.H., U.P.D., C.B., J.A.B., J.P.J.); and Department of Pharmacology and Experimental Therapeutics, and the Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, New Orleans, Louisiana (J.R.R., J.W.P., W.L.B.)
| | - Pavel Anzenbacher
- Departments of Medicinal Chemistry and Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas (D.F.E, J.S.L., E.E.S.); Division of Cancer Research, School of Medicine, University of Dundee, Ninewells Hospital, Dundee, United Kingdom (C.R.W., C.J.H., L.A.M.); Regional Center of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science (M.O., M.P., V.N., K.B.) and Department of Pharmacology, Faculty of Medicine and Dentistry (P.A.), Palacký University, Olomouc, Czech Republic; Department of Chemistry, Washington State University, Pullman, Washington (S.C.H., U.P.D., C.B., J.A.B., J.P.J.); and Department of Pharmacology and Experimental Therapeutics, and the Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, New Orleans, Louisiana (J.R.R., J.W.P., W.L.B.)
| | - Upendra P Dahal
- Departments of Medicinal Chemistry and Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas (D.F.E, J.S.L., E.E.S.); Division of Cancer Research, School of Medicine, University of Dundee, Ninewells Hospital, Dundee, United Kingdom (C.R.W., C.J.H., L.A.M.); Regional Center of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science (M.O., M.P., V.N., K.B.) and Department of Pharmacology, Faculty of Medicine and Dentistry (P.A.), Palacký University, Olomouc, Czech Republic; Department of Chemistry, Washington State University, Pullman, Washington (S.C.H., U.P.D., C.B., J.A.B., J.P.J.); and Department of Pharmacology and Experimental Therapeutics, and the Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, New Orleans, Louisiana (J.R.R., J.W.P., W.L.B.)
| | - Carlo Barnaba
- Departments of Medicinal Chemistry and Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas (D.F.E, J.S.L., E.E.S.); Division of Cancer Research, School of Medicine, University of Dundee, Ninewells Hospital, Dundee, United Kingdom (C.R.W., C.J.H., L.A.M.); Regional Center of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science (M.O., M.P., V.N., K.B.) and Department of Pharmacology, Faculty of Medicine and Dentistry (P.A.), Palacký University, Olomouc, Czech Republic; Department of Chemistry, Washington State University, Pullman, Washington (S.C.H., U.P.D., C.B., J.A.B., J.P.J.); and Department of Pharmacology and Experimental Therapeutics, and the Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, New Orleans, Louisiana (J.R.R., J.W.P., W.L.B.)
| | - James A Brozik
- Departments of Medicinal Chemistry and Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas (D.F.E, J.S.L., E.E.S.); Division of Cancer Research, School of Medicine, University of Dundee, Ninewells Hospital, Dundee, United Kingdom (C.R.W., C.J.H., L.A.M.); Regional Center of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science (M.O., M.P., V.N., K.B.) and Department of Pharmacology, Faculty of Medicine and Dentistry (P.A.), Palacký University, Olomouc, Czech Republic; Department of Chemistry, Washington State University, Pullman, Washington (S.C.H., U.P.D., C.B., J.A.B., J.P.J.); and Department of Pharmacology and Experimental Therapeutics, and the Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, New Orleans, Louisiana (J.R.R., J.W.P., W.L.B.)
| | - Jeffrey P Jones
- Departments of Medicinal Chemistry and Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas (D.F.E, J.S.L., E.E.S.); Division of Cancer Research, School of Medicine, University of Dundee, Ninewells Hospital, Dundee, United Kingdom (C.R.W., C.J.H., L.A.M.); Regional Center of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science (M.O., M.P., V.N., K.B.) and Department of Pharmacology, Faculty of Medicine and Dentistry (P.A.), Palacký University, Olomouc, Czech Republic; Department of Chemistry, Washington State University, Pullman, Washington (S.C.H., U.P.D., C.B., J.A.B., J.P.J.); and Department of Pharmacology and Experimental Therapeutics, and the Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, New Orleans, Louisiana (J.R.R., J.W.P., W.L.B.)
| | - D Fernando Estrada
- Departments of Medicinal Chemistry and Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas (D.F.E, J.S.L., E.E.S.); Division of Cancer Research, School of Medicine, University of Dundee, Ninewells Hospital, Dundee, United Kingdom (C.R.W., C.J.H., L.A.M.); Regional Center of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science (M.O., M.P., V.N., K.B.) and Department of Pharmacology, Faculty of Medicine and Dentistry (P.A.), Palacký University, Olomouc, Czech Republic; Department of Chemistry, Washington State University, Pullman, Washington (S.C.H., U.P.D., C.B., J.A.B., J.P.J.); and Department of Pharmacology and Experimental Therapeutics, and the Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, New Orleans, Louisiana (J.R.R., J.W.P., W.L.B.)
| | - Jennifer S Laurence
- Departments of Medicinal Chemistry and Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas (D.F.E, J.S.L., E.E.S.); Division of Cancer Research, School of Medicine, University of Dundee, Ninewells Hospital, Dundee, United Kingdom (C.R.W., C.J.H., L.A.M.); Regional Center of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science (M.O., M.P., V.N., K.B.) and Department of Pharmacology, Faculty of Medicine and Dentistry (P.A.), Palacký University, Olomouc, Czech Republic; Department of Chemistry, Washington State University, Pullman, Washington (S.C.H., U.P.D., C.B., J.A.B., J.P.J.); and Department of Pharmacology and Experimental Therapeutics, and the Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, New Orleans, Louisiana (J.R.R., J.W.P., W.L.B.)
| | - Ji Won Park
- Departments of Medicinal Chemistry and Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas (D.F.E, J.S.L., E.E.S.); Division of Cancer Research, School of Medicine, University of Dundee, Ninewells Hospital, Dundee, United Kingdom (C.R.W., C.J.H., L.A.M.); Regional Center of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science (M.O., M.P., V.N., K.B.) and Department of Pharmacology, Faculty of Medicine and Dentistry (P.A.), Palacký University, Olomouc, Czech Republic; Department of Chemistry, Washington State University, Pullman, Washington (S.C.H., U.P.D., C.B., J.A.B., J.P.J.); and Department of Pharmacology and Experimental Therapeutics, and the Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, New Orleans, Louisiana (J.R.R., J.W.P., W.L.B.)
| | - Wayne L Backes
- Departments of Medicinal Chemistry and Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas (D.F.E, J.S.L., E.E.S.); Division of Cancer Research, School of Medicine, University of Dundee, Ninewells Hospital, Dundee, United Kingdom (C.R.W., C.J.H., L.A.M.); Regional Center of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science (M.O., M.P., V.N., K.B.) and Department of Pharmacology, Faculty of Medicine and Dentistry (P.A.), Palacký University, Olomouc, Czech Republic; Department of Chemistry, Washington State University, Pullman, Washington (S.C.H., U.P.D., C.B., J.A.B., J.P.J.); and Department of Pharmacology and Experimental Therapeutics, and the Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, New Orleans, Louisiana (J.R.R., J.W.P., W.L.B.)
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22
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Zhang M, Huang R, Ackermann R, Im SC, Waskell L, Schwendeman A, Ramamoorthy A. Reconstitution of the Cytb5-CytP450 Complex in Nanodiscs for Structural Studies using NMR Spectroscopy. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201600073] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Meng Zhang
- Department of Chemistry; University of Michigan; Ann Arbor MI 48109-1055 USA
| | - Rui Huang
- Department of Chemistry; University of Michigan; Ann Arbor MI 48109-1055 USA
| | - Rose Ackermann
- Department of Medicinal Chemistry; The Biointerfaces Institute; University of Michigan; North Campus Research Complex; Ann Arbor MI 48109 USA
| | - Sang-Choul Im
- Department of Anesthesiology; University of Michigan and VA Medical Center; Ann Arbor MI 48105 USA
| | - Lucy Waskell
- Department of Anesthesiology; University of Michigan and VA Medical Center; Ann Arbor MI 48105 USA
| | - Anna Schwendeman
- Department of Medicinal Chemistry; The Biointerfaces Institute; University of Michigan; North Campus Research Complex; Ann Arbor MI 48109 USA
| | - Ayyalusamy Ramamoorthy
- Biophysics and Department of Chemistry; University of Michigan; Ann Arbor MI 48109-1055 USA
- Department of Chemistry; University of Michigan; Ann Arbor MI 48109-1055 USA
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23
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Zhang M, Huang R, Ackermann R, Im SC, Waskell L, Schwendeman A, Ramamoorthy A. Reconstitution of the Cytb5-CytP450 Complex in Nanodiscs for Structural Studies using NMR Spectroscopy. Angew Chem Int Ed Engl 2016; 55:4497-9. [PMID: 26924779 DOI: 10.1002/anie.201600073] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 01/22/2016] [Indexed: 11/05/2022]
Abstract
Cytochrome P450s (P450s) are a superfamily of enzymes responsible for the catalysis of a wide range of substrates. Dynamic interactions between full-length membrane-bound P450 and its redox partner cytochrome b5 (cytb5 ) have been found to be important for the enzymatic activity of P450. However, the stability of the circa 70 kDa membrane-bound complex in model membranes renders high-resolution structural NMR studies particularly difficult. To overcome these challenges, reconstitution of the P450-cytb5 complex in peptide-based nanodiscs, containing no detergents, has been demonstrated, which are characterized by size exclusion chromatography and NMR spectroscopy. In addition, NMR experiments are used to identify the binding interface of the P450-cytb5 complex in the nanodisc. This is the first successful demonstration of a protein-protein complex in a nanodisc using NMR structural studies and should be useful to obtain valuable structural information on membrane-bound protein complexes.
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Affiliation(s)
- Meng Zhang
- Department of Chemistry, University of Michigan, Ann Arbor, MI, 48109-1055, USA
| | - Rui Huang
- Department of Chemistry, University of Michigan, Ann Arbor, MI, 48109-1055, USA
| | - Rose Ackermann
- Department of Medicinal Chemistry, The Biointerfaces Institute, University of Michigan, North Campus Research Complex, Ann Arbor, MI, 48109, USA
| | - Sang-Choul Im
- Department of Anesthesiology, University of Michigan and VA Medical Center, Ann Arbor, MI, 48105, USA
| | - Lucy Waskell
- Department of Anesthesiology, University of Michigan and VA Medical Center, Ann Arbor, MI, 48105, USA
| | - Anna Schwendeman
- Department of Medicinal Chemistry, The Biointerfaces Institute, University of Michigan, North Campus Research Complex, Ann Arbor, MI, 48109, USA
| | - Ayyalusamy Ramamoorthy
- Biophysics and Department of Chemistry, University of Michigan, Ann Arbor, MI, 48109-1055, USA. .,Department of Chemistry, University of Michigan, Ann Arbor, MI, 48109-1055, USA.
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24
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Estrada DF, Laurence JS, Scott EE. Cytochrome P450 17A1 Interactions with the FMN Domain of Its Reductase as Characterized by NMR. J Biol Chem 2015; 291:3990-4003. [PMID: 26719338 DOI: 10.1074/jbc.m115.677294] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Indexed: 11/06/2022] Open
Abstract
To accomplish key physiological processes ranging from drug metabolism to steroidogenesis, human microsomal cytochrome P450 enzymes require the sequential input of two electrons delivered by the FMN domain of NADPH-cytochrome P450 reductase. Although some human microsomal P450 enzymes can instead accept the second electron from cytochrome b5, for human steroidogenic CYP17A1, the cytochrome P450 reductase FMN domain delivers both electrons, and b5 is an allosteric modulator. The structural basis of these key but poorly understood protein interactions was probed by solution NMR using the catalytically competent soluble domains of each protein. Formation of the CYP17A1·FMN domain complex induced differential line broadening of the NMR signal for each protein. Alterations in the exchange dynamics generally occurred for residues near the surface of the flavin mononucleotide, including 87-90 (loop 1), and for key CYP17A1 active site residues. These interactions were modulated by the identity of the substrate in the buried CYP17A1 active site and by b5. The FMN domain outcompetes b5 for binding to CYP17A1 in the three-component system. These results and comparison with previous NMR studies of the CYP17A1·b5 complex suggest a model of CYP17A1 enzyme regulation.
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Affiliation(s)
- D Fernando Estrada
- From the Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas 66045 and
| | - Jennifer S Laurence
- the Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, Kansas 66047
| | - Emily E Scott
- From the Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas 66045 and
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25
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Storbeck KH, Swart AC, Fox CL, Swart P. Cytochrome b5 modulates multiple reactions in steroidogenesis by diverse mechanisms. J Steroid Biochem Mol Biol 2015; 151:66-73. [PMID: 25446886 DOI: 10.1016/j.jsbmb.2014.11.024] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 11/02/2014] [Accepted: 11/21/2014] [Indexed: 12/18/2022]
Abstract
Cytochrome b5 (cyt-b5) is a relatively small haemoprotein which plays an important role in the regulation of mammalian steroidogenesis. This unique protein has the ability to modulate the activity of key steroidogenic enzymes via a number of diverse reaction mechanisms. Cyt-b5 can augment the 17,20-lyase activity of CYP17A1 by promoting the interaction of CYP17A1 and POR; enhance the 16-ene-synthase activity of CYP17A1 by acting as an electron donor; and enhance the activity of 3βHSD by increasing the affinity of 3βHSD for its cofactor NAD(+). We review the modulation of CYP17A1 and 3βHSD activity by cyt-b5 and discuss the reaction mechanisms associated with each activity. The physiological importance of cyt-b5 in regulating mammalian steroidogenesis is presented and the impact of inactivating cyt-b5 mutations are reviewed. This article is part of a Special Issue entitled 'Steroid/Sterol signaling'.
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Affiliation(s)
- Karl-Heinz Storbeck
- Department of Biochemistry, University of Stellenbosch, Stellenbosch 7600, South Africa
| | - Amanda C Swart
- Department of Biochemistry, University of Stellenbosch, Stellenbosch 7600, South Africa
| | - Cheryl L Fox
- Department of Biochemistry, University of Stellenbosch, Stellenbosch 7600, South Africa
| | - Pieter Swart
- Department of Biochemistry, University of Stellenbosch, Stellenbosch 7600, South Africa.
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26
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Zhang M, Huang R, Im SC, Waskell L, Ramamoorthy A. Effects of membrane mimetics on cytochrome P450-cytochrome b5 interactions characterized by NMR spectroscopy. J Biol Chem 2015; 290:12705-18. [PMID: 25795780 DOI: 10.1074/jbc.m114.597096] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Indexed: 01/08/2023] Open
Abstract
Mammalian cytochrome P450 (P450) is a membrane-bound monooxygenase whose catalytic activities require two electrons to be sequentially delivered from its redox partners: cytochrome b5 (cytb5) and cytochrome P450 reductase, both of which are membrane proteins. Although P450 functional activities are known to be affected by lipids, experimental evidence to reveal the effect of membrane on P450-cytb5 interactions is still lacking. Here, we present evidence for the influence of phospholipid bilayers on complex formation between rabbit P450 2B4 (CYP2B4) and rabbit cytb5 at the atomic level, utilizing NMR techniques. General line broadening and modest chemical shift perturbations of cytb5 resonances characterize CYP2B4-cytb5 interactions on the intermediate time scale. More significant intensity attenuation and a more specific protein-protein binding interface are observed in bicelles as compared with lipid-free solution, highlighting the importance of the lipid bilayer in stabilizing stronger and more specific interactions between CYP2B4 and cytb5, which may lead to a more efficient electron transfer. Similar results observed for the interactions between CYP2B4 lacking the transmembrane domain (tr-CYP2B4) and cytb5 imply interactions between tr-CYP2B4 and the membrane surface, which might assist in CYP2B4-cytb5 complex formation by orienting tr-CYP2B4 for efficient contact with cytb5. Furthermore, the observation of weak and nonspecific interactions between CYP2B4 and cytb5 in micelles suggests that lipid bilayer structures and low curvature membrane surface are preferable for CYP2B4-cytb5 complex formation. Results presented in this study provide structural insights into the mechanism behind the important role that the lipid bilayer plays in the interactions between P450s and their redox partners.
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Affiliation(s)
- Meng Zhang
- From the Department of Chemistry and Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055 and
| | - Rui Huang
- From the Department of Chemistry and Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055 and
| | - Sang-Choul Im
- the Department of Anesthesiology, University of Michigan and Veterans Affairs Medical Center, Ann Arbor, Michigan 48105
| | - Lucy Waskell
- the Department of Anesthesiology, University of Michigan and Veterans Affairs Medical Center, Ann Arbor, Michigan 48105
| | - Ayyalusamy Ramamoorthy
- From the Department of Chemistry and Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055 and
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27
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Insights into the role of substrates on the interaction between cytochrome b5 and cytochrome P450 2B4 by NMR. Sci Rep 2015; 5:8392. [PMID: 25687717 PMCID: PMC4330534 DOI: 10.1038/srep08392] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 12/16/2014] [Indexed: 01/08/2023] Open
Abstract
Mammalian cytochrome b5 (cyt b5) is a membrane-bound protein capable of donating an electron to cytochrome P450 (P450) in the P450 catalytic cycle. The interaction between cyt b5 and P450 has been reported to be affected by the substrates of P450; however, the mechanism of substrate modulation on the cyt b5-P450 complex formation is still unknown. In this study, the complexes between full-length rabbit cyt b5 and full-length substrate-free/substrate-bound cytochrome P450 2B4 (CYP2B4) are investigated using NMR techniques. Our findings reveal that the population of complexes is ionic strength dependent, implying the importance of electrostatic interactions in the complex formation process. The observation that the cyt b5-substrate-bound CYP2B4 complex shows a weaker dependence on ionic strength than the cyt b5-substrate-free CYP2B4 complex suggests the presence of a larger fraction of steoreospecific complexes when CYP2B4 is substrate-bound. These results suggest that a CYP2B4 substrate likely promotes specific interactions between cyt b5 and CYP2B4. Residues D65, V66, T70, D71 and A72 are found to be involved in specific interactions between the two proteins due to their weak response to ionic strength change. These findings provide insights into the mechanism underlying substrate modulation on the cyt b5-P450 complexation process.
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28
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Jeřábek P, Florián J, Stiborová M, Martínek V. Flexible docking-based molecular dynamics/steered molecular dynamics calculations of protein-protein contacts in a complex of cytochrome P450 1A2 with cytochrome b5. Biochemistry 2014; 53:6695-705. [PMID: 25313797 DOI: 10.1021/bi500814t] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Formation of transient complexes of cytochrome P450 (P450) with another protein of the endoplasmic reticulum membrane, cytochrome b5 (cyt b5), dictates the catalytic activities of several P450s. Therefore, we examined formation and binding modes of the complex of human P450 1A2 with cyt b5. Docking of soluble domains of these proteins was performed using an information-driven flexible docking approach implemented in HADDOCK. Stabilities of the five unique binding modes of the P450 1A2-cyt b5 complex yielded by HADDOCK were evaluated using explicit 10 ns molecular dynamics (MD) simulations in aqueous solution. Further, steered MD was used to compare the stability of the individual P450 1A2-cyt b5 binding modes. The best binding mode was characterized by a T-shaped mutual orientation of the porphyrin rings and a 10.7 Å distance between the two redox centers, thus satisfying the condition for a fast electron transfer. Mutagenesis studies and chemical cross-linking, which, in the absence of crystal structures, were previously used to deduce specific P450-cyt b5 interactions, indicated that the negatively charged convex surface of cyt b5 binds to the positively charged concave surface of P450. Our simulations further elaborate structural details of this interface, including nine ion pairs between R95, R100, R138, R362, K442, K455, and K465 side chains of P450 1A2 and E42, E43, E49, D65, D71, and heme propionates of cyt b5. The universal heme-centric system of internal coordinates was proposed to facilitate consistent classification of the orientation of the two porphyrins in any protein complex.
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Affiliation(s)
- Petr Jeřábek
- Department of Biochemistry, Faculty of Science, Charles University in Prague , Albertov 2030, 128 43 Prague 2, Czech Republic
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29
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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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30
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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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31
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Electrochemistry of mammalian cytochrome P450 2B4 indicates tunable thermodynamic parameters in surfactant films. J Inorg Biochem 2013; 129:30-4. [PMID: 24013063 DOI: 10.1016/j.jinorgbio.2013.07.039] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 07/28/2013] [Accepted: 07/29/2013] [Indexed: 11/23/2022]
Abstract
Electrochemical methods continue to present an attractive means for achieving in vitro biocatalysis with cytochromes P450; however understanding fully the nature of electrode-bound P450 remains elusive. Herein we report thermodynamic parameters using electrochemical analysis of full-length mammalian microsomal cytochrome P450 2B4 (CYP 2B4) in didodecyldimethylammonium bromide (DDAB) surfactant films. Electronic absorption spectra of CYP 2B4-DDAB films on silica slides reveal an absorption maximum at 418nm, characteristic of low-spin, six-coordinate, water-ligated Fe(III) heme in P450. The Fe(III/II) and Fe(II/I) redox couples (E1/2) of substrate-free CYP 2B4 measured by cyclic voltammetry are -0.23V and -1.02V (vs. SCE, or 14mV and -776mV vs. NHE) at 21°C. The standard heterogeneous rate constant for electron transfer from the electrode to the heme for the Fe(III/II) couple was estimated at 170s(-1). Experiments indicate that the system is capable of catalytic reduction of dioxygen, however substrate oxidation was not observed. From the variation of E1/2 with temperature (18-40°C), we have measured entropy and enthalpy changes that accompany heme reduction, -151Jmol(-1)K(-1) and -46kJmol(-1), respectfully. The corresponding entropy and enthalpy values are less for the six-coordinate low-spin, imidazole-ligated enzyme (-59Jmol(-1)K(-1) and -18kJmol(-1)), consistent with limited conformational changes upon reduction. These thermodynamic parameters are comparable to those measured for bacterial P450 from Bacillus megaterium (CYP BM3), confirming our prior reports that the surfactant environment exerts a strong influence on the redox properties of the heme.
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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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Ahuja S, Jahr N, Im SC, Vivekanandan S, Popovych N, Le Clair SV, Huang R, Soong R, Xu J, Yamamoto K, Nanga RP, Bridges A, Waskell L, Ramamoorthy A. A model of the membrane-bound cytochrome b5-cytochrome P450 complex from NMR and mutagenesis data. J Biol Chem 2013; 288:22080-95. [PMID: 23709268 DOI: 10.1074/jbc.m112.448225] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Microsomal cytochrome b5 (cytb5) is a membrane-bound protein that modulates the catalytic activity of its redox partner, cytochrome P4502B4 (cytP450). Here, we report the first structure of full-length rabbit ferric microsomal cytb5 (16 kDa), incorporated in two different membrane mimetics (detergent micelles and lipid bicelles). Differential line broadening of the cytb5 NMR resonances and site-directed mutagenesis data were used to characterize the cytb5 interaction epitope recognized by ferric microsomal cytP450 (56 kDa). Subsequently, a data-driven docking algorithm, HADDOCK (high ambiguity driven biomolecular docking), was used to generate the structure of the complex between cytP4502B4 and cytb5 using experimentally derived restraints from NMR, mutagenesis, and the double mutant cycle data obtained on the full-length proteins. Our docking and experimental results point to the formation of a dynamic electron transfer complex between the acidic convex surface of cytb5 and the concave basic proximal surface of cytP4502B4. The majority of the binding energy for the complex is provided by interactions between residues on the C-helix and β-bulge of cytP450 and residues at the end of helix α4 of cytb5. The structure of the complex allows us to propose an interprotein electron transfer pathway involving the highly conserved Arg-125 on cytP450 serving as a salt bridge between the heme propionates of cytP450 and cytb5. We have also shown that the addition of a substrate to cytP450 likely strengthens the cytb5-cytP450 interaction. This study paves the way to obtaining valuable structural, functional, and dynamic information on membrane-bound complexes.
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Affiliation(s)
- Shivani Ahuja
- Department of Chemistry and Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, USA
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Estrada DF, Laurence JS, Scott EE. Substrate-modulated cytochrome P450 17A1 and cytochrome b5 interactions revealed by NMR. J Biol Chem 2013; 288:17008-17018. [PMID: 23620596 DOI: 10.1074/jbc.m113.468926] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The membrane heme protein cytochrome b5 (b5) can enhance, inhibit, or have no effect on cytochrome P450 (P450) catalysis, depending on the specific P450, substrate, and reaction conditions, but the structural basis remains unclear. Here the interactions between the soluble domain of microsomal b5 and the catalytic domain of the bifunctional steroidogenic cytochrome P450 17A1 (CYP17A1) were investigated. CYP17A1 performs both steroid hydroxylation, which is unaffected by b5, and an androgen-forming lyase reaction that is facilitated 10-fold by b5. NMR chemical shift mapping of b5 titrations with CYP17A1 indicates that the interaction occurs in an intermediate exchange regime and identifies charged surface residues involved in the protein/protein interface. The role of these residues is confirmed by disruption of the complex upon mutagenesis of either the anionic b5 residues (Glu-48 or Glu-49) or the corresponding cationic CYP17A1 residues (Arg-347, Arg-358, or Arg-449). Cytochrome b5 binding to CYP17A1 is also mutually exclusive with binding of NADPH-cytochrome P450 reductase. To probe the differential effects of b5 on the two CYP17A1-mediated reactions and, thus, communication between the superficial b5 binding site and the buried CYP17A1 active site, CYP17A1/b5 complex formation was characterized with either hydroxylase or lyase substrates bound to CYP17A1. Significantly, the CYP17A1/b5 interaction is stronger when the hydroxylase substrate pregnenolone is present in the CYP17A1 active site than when the lyase substrate 17α-hydroxypregnenolone is in the active site. These findings form the basis for a clearer understanding of this important interaction by directly measuring the reversible binding of the two proteins, providing evidence of communication between the CYP17A1 active site and the superficial proximal b5 binding site.
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Affiliation(s)
| | | | - Emily E Scott
- Departments of Medicinal Chemistry, Lawrence, Kansas 66045.
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Henderson CJ, McLaughlin LA, Wolf CR. Evidence that cytochrome b5 and cytochrome b5 reductase can act as sole electron donors to the hepatic cytochrome P450 system. Mol Pharmacol 2013; 83:1209-17. [PMID: 23530090 DOI: 10.1124/mol.112.084616] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
We previously described the development of genetic models to study the in vivo functions of the hepatic cytochrome P450 (P450) system, through the hepatic deletion of either cytochrome P450 oxidoreductase [POR; HRN (hepatic reductase null) line] or cytochrome b(5) [HBN (hepatic cytochrome b(5) null) line]. However, HRN mice still exhibit low levels of mono-oxygenase activity in spite of the absence of detectable reductase protein. To investigate whether this is because cytochrome b(5) and cytochrome b(5) reductase can act as the sole electron donor to the P450 system, we crossed HRN with HBN mice to generate a line lacking hepatic expression of both electron donors (HBRN). HBRN mice exhibited exacerbation of the phenotypic characteristics of the HRN line: liver enlargement, hepatosteatosis, and increased expression of certain P450s. Also, drug metabolizing activities in vitro were further reduced relative to the HRN model, in some cases to undetectable levels. Pharmacokinetic studies in vivo demonstrated that midazolam half-life, C(max), and area under the concentration-time curve were increased, and clearance was decreased, to a greater extent in the HBRN line than in either the HBN or HRN model. Microsomal incubations using NADPH concentrations below the apparent K(m) of cytochrome b(5) reductase, but well above that for POR, led to the virtual elimination of 7-benzyloxyquinoline turnover in HRN samples. These data provide strong evidence that cytochrome b(5)/cytochrome b(5) reductase can act as a sole electron donor to the P450 system in vitro and in vivo.
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Affiliation(s)
- Colin J Henderson
- Division of Cancer Research, Medical Research Institute, University of Dundee, Jacqui Wood Cancer Centre, Ninewells Hospitaland Medical School, Dundee, United Kingdom
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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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Tang T, Zhao C, Feng X, Liu X, Qiu L. Knockdown of several components of cytochrome P450 enzyme systems by RNA interference enhances the susceptibility of Helicoverpa armigera to fenvalerate. PEST MANAGEMENT SCIENCE 2012; 68:1501-11. [PMID: 22689565 DOI: 10.1002/ps.3336] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 03/15/2012] [Accepted: 04/04/2012] [Indexed: 05/03/2023]
Abstract
BACKGROUND The function of cytochrome P450 proteins (P450s) in the metabolism of a variety of compounds by oxidation and reduction is well elucidated, but its interactions with other electron transfer components in the pyrethroid resistance of insect pests have been a mystery for a long time. In previous studies the authors cloned and characterised CYP6B7 and cytochrome b(5) (Cyt-b(5)) in the fenvalerate-resistant HDFR strain of cotton bollworm (Helicoverpa armigera Hübner) and showed that CYP6B7 mRNA was overexpressed and important for resistance to fenvalerate. In the present study, the functional interactions of CYP6B7, NADPH-dependent cytochrome P450 reductase (CPR) and Cyt-b(5) were assessed using RNA interference (RNAi) strategies and monitoring for fenvalerate resistance levels. RESULTS RT-qPCR analyses indicated that the expression levels of CYP6B7, CPR and Cyt-b(5) mRNA were decreased drastically in the midgut of fourth-instar larvae of the H. armigera HDFR strain after corresponding double-stranded RNA (dsRNA) injection, compared with that of the control. The knockdown of CYP6B7, CPR and Cyt-b(5) transcripts was time course dependent during a 12-48 h period after dsRNA injection. At the earlier time points analysed, significant suppression of CYP6B7 mRNA levels was observed in larvae injected with dsCYP6B7-313 as compared with controls, and further suppression was observed in larvae injected with dsCYP6B7-313, dsCPR-403 and dsCyt-b(5) . The injection of dsCYP6B7-313 together with dsCPR-403 and dsCyt-b(5) increased larval susceptibility of the HDFR strain to fenvalerate. CONCLUSION The results demonstrated that silencing of CYP6B7 alone or CYP6B7 together with CPR and/or Cyt-b(5) increased the susceptibility of H. armigera to fenvalerate, suggesting that CYP6B7, CPR and Cyt-b(5) collaboratively participated in enhanced metabolism of fenvalerate and played an important role in the resistance of H. armigera to fenvalerate.
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Affiliation(s)
- Tao Tang
- Key Laboratory of Pesticide Chemistry and Application Technology, Ministry of Agriculture, College of Science, China Agricultural University, Beijing, China
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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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Xu C, Ogburn ET, Guo Y, Desta Z. Effects of the CYP2B6*6 allele on catalytic properties and inhibition of CYP2B6 in vitro: implication for the mechanism of reduced efavirenz metabolism and other CYP2B6 substrates in vivo. Drug Metab Dispos 2012; 40:717-25. [PMID: 22232427 DOI: 10.1124/dmd.111.042416] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The mechanism by which CYP2B6*6 allele alters drug metabolism in vitro and in vivo is not fully understood. To test the hypothesis that altered substrate binding and/or catalytic properties contribute to its functional consequences, efavirenz 8-hydroxylation and bupropion 4-hydroxylation were determined in CYP2B6.1 and CYP2B6.6 proteins expressed without and with cytochrome b5 (Cyt b5) and in human liver microsomes (HLMs) obtained from liver tissues genotyped for the CYP2B6*6 allele. The susceptibility of the variant protein to inhibition was also tested in HLMs. Significantly higher V(max) and K(m) values for 8-hydroxyefavirenz formation and ∼2-fold lower intrinsic clearance (Cl(int)) were noted in expressed CYP2B6.6 protein (-b5) compared with that of CYP2B6.1 protein (-b5); this effect was abolished by Cyt b5. The V(max) and Cl(int) values for 4-hydroxybupropion formation were significantly higher in CYP2B6.6 than in CYP2B6.1 protein, with no difference in K(m), whereas coexpression with Cyt b5 reversed the genetic effect on these kinetic parameters. In HLMs, CYP2B6*6/*6 genotype was associated with markedly lower V(max) (and moderate increase in K(m)) and thus lower Cl(int) values for efavirenz and bupropion metabolism, but no difference in catalytic properties was noted between CYP2B6*1/*1 and CYP2B6*1/*6 genotypes. Inhibition of efavirenz 8-hydroxylation by voriconazole was significantly greater in HLMs with the CYP2B6*6 allele (K(i) = 1.6 ± 0.8 μM) than HLMs with CYP2B6*1/*1 genotype (K(i) = 3.0 ± 1.1 μM). In conclusion, our data suggest the CYP2B6*6 allele influences metabolic activity by altering substrate binding and catalytic activity in a substrate- and Cyt b5-dependent manner. It may also confer susceptibility to inhibition.
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Affiliation(s)
- Cong Xu
- Indiana University School of Medicine, Indianapolis, IN 46202, USA
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41
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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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Abstract
This review focuses on the interrelationship between ageing and autophagy. There is a striking similarity between the signalling aspects of these two processes. Both ageing and autophagy involve several of the signalling components such as insulin/IGF-1, AMPK, Ras-cAMP-PKA, Sch9 and mTOR. Ageing and ageing-mediated defective autophagy involve accumulation of lipofuscin. Components of anti-ageing and autophagy include SirTs and FoxOs. Nutritional deprivation or calorie restriction as well as several nutriceuticals including resveratrol, spermidine, curcumin and piperine can enhance autophagy and increase lifespan. Such striking similarities indicate that lifespan is strongly dependent on autophagy.
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Affiliation(s)
- Goran Petrovski
- Department of Biochemistry and Molecular Biology, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary
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The interaction of microsomal cytochrome P450 2B4 with its redox partners, cytochrome P450 reductase and cytochrome b(5). Arch Biochem Biophys 2010; 507:144-53. [PMID: 21055385 DOI: 10.1016/j.abb.2010.10.023] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Revised: 10/27/2010] [Accepted: 10/28/2010] [Indexed: 11/21/2022]
Abstract
Cytochrome P450 2B4 is a microsomal protein with a multi-step reaction cycle similar to that observed in the majority of other cytochromes P450. The cytochrome P450 2B4-substrate complex is reduced from the ferric to the ferrous form by cytochrome P450 reductase. After binding oxygen, the oxyferrous protein accepts a second electron which is provided by either cytochrome P450 reductase or cytochrome b(5). In both instances, product formation occurs. When the second electron is donated by cytochrome b(5), catalysis (product formation) is ∼10- to 100-fold faster than in the presence of cytochrome P450 reductase. This allows less time for side product formation (hydrogen peroxide and superoxide) and improves by ∼15% the coupling of NADPH consumption to product formation. Cytochrome b(5) has also been shown to compete with cytochrome P450 reductase for a binding site on the proximal surface of cytochrome P450 2B4. These two different effects of cytochrome b(5) on cytochrome P450 2B4 reactivity can explain how cytochrome b(5) is able to stimulate, inhibit, or have no effect on cytochrome P450 2B4 activity. At low molar ratios (<1) of cytochrome b(5) to cytochrome P450 reductase, the more rapid catalysis results in enhanced substrate metabolism. In contrast, at high molar ratios (>1) of cytochrome b(5) to cytochrome P450 reductase, cytochrome b(5) inhibits activity by binding to the proximal surface of cytochrome P450 and preventing the reductase from reducing ferric cytochrome P450 to the ferrous protein, thereby aborting the catalytic reaction cycle. When the stimulatory and inhibitory effects of cytochrome b(5) are equal, it will appear to have no effect on the enzymatic activity. It is hypothesized that cytochrome b(5) stimulates catalysis by causing a conformational change in the active site, which allows the active oxidizing oxyferryl species of cytochrome P450 to be formed more rapidly than in the presence of reductase.
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Pratt-Hyatt M, Zhang H, Snider NT, Hollenberg PF. Effects of a commonly occurring genetic polymorphism of human CYP3A4 (I118V) on the metabolism of anandamide. Drug Metab Dispos 2010; 38:2075-82. [PMID: 20702771 DOI: 10.1124/dmd.110.033712] [Citation(s) in RCA: 25] [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 endocannabinoid system plays an important role in numerous physiological processes including mood, appetite, and pain sensation. A critical compound in maintaining cannabinoid tone is the endocannabinoid anandamide (AEA). We have recently shown that AEA is metabolized by several different human cytochromes P450 (P450) to form a number of metabolites, one of which exhibits increased biological activity. CYP3A4, one of the major P450s involved in the metabolism of AEA, produces four major metabolites. One of these metabolites, 5,6-epoxyeicosatrienoic acid ethanolamide (5,6-EET-EA), exhibits a much higher affinity than AEA for the cannabinoid 2 receptor (CB-2), which leads to a marked decrease in intracellular cAMP levels in cells expressing CB-2. There are multiple human alleles of CYP3A4, and the CYP3A4.4 allele has been shown to exhibit a significant decrease in activity. Recombinant CYP3A4*4 was expressed in Escherichia coli and was demonstrated to produce 60% less 6-hydroxytestosterone than the wild-type (WT) 3A4 in a reconstituted system. The metabolism of AEA by the WT and the CYP3A4.4 variant was investigated. The mutant produced 60% less of the four EET-EA metabolites than the WT. The mutant also produced a new peak on liquid chromatography-mass spectrometry not seen with the WT, which corresponded to 19-hydroxyeicosatetraenoic acid-ethanolamide. In addition, the mutant produces four novel peaks at m/z 380, which correspond to the addition of two oxygen atoms, possibly to form a peroxide bond. These data indicate that individuals expressing the CYP3A4.4 allele may exhibit significant variations in the metabolism of AEA as well as any other compounds resembling AEA.
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Affiliation(s)
- Matthew Pratt-Hyatt
- Departments of Pharmacology, University of Michigan School of Medicine, Ann Arbor, Michigan 48109-5632, USA
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McLaughlin LA, Ronseaux S, Finn RD, Henderson CJ, Roland Wolf C. Deletion of microsomal cytochrome b5 profoundly affects hepatic and extrahepatic drug metabolism. Mol Pharmacol 2010; 78:269-78. [PMID: 20430864 DOI: 10.1124/mol.110.064246] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We demonstrated recently that cytochrome b(5) plays an important in vivo role in hepatic cytochrome P450 (P450) function [J Biol Chem 283:31385-31393, 2008]. We have now generated a model in which cytochrome b(5) has been deleted in all tissues [cytochrome b(5) complete null (BCN)], which surprisingly results in a viable mouse despite the putative in vivo roles of this protein in lipid and steroid hormone metabolism and the reduction of methemoglobin. In contrast to the liver-specific deletion, complete deletion of cytochrome b(5) leads to a neonatal increase in the expression of many hepatic P450s at both the protein and mRNA level. In extrahepatic tissues, some changes in P450 expression were also observed that were isoform-dependent. In vitro cytochrome P450 activities in liver, kidney, lung, and small intestine of BCN mice were determined for a range of model substrates and probe drugs; a profound reduction in the metabolism of some substrates, particularly in lung, kidney, and small intestine, was observed. In vivo, the metabolism of metoprolol was significantly altered in BCN mice, in contrast to the previous finding in the liver-specific cytochrome b(5) deletion, suggesting that extrahepatic cytochrome b(5) plays a significant role in its disposition. Testicular Cyp17 hydroxylase and lyase activities were also significantly reduced by cytochrome b(5) deletion, leading to significantly lower levels of testicular testosterone. The BCN mouse provides an additional model system with which to further investigate the functions of cytochrome b(5), particularly in extrahepatic tissues.
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Affiliation(s)
- Lesley A McLaughlin
- Cancer Research UK Molecular Pharmacology Unit, Biomedical Research Institute, Ninewells Hospital & Medical School, Dundee, United Kingdom
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Zhang H, Kenaan C, Hamdane D, Hoa GHB, Hollenberg PF. Effect of conformational dynamics on substrate recognition and specificity as probed by the introduction of a de novo disulfide bond into cytochrome P450 2B1. J Biol Chem 2009; 284:25678-86. [PMID: 19605359 PMCID: PMC2757969 DOI: 10.1074/jbc.m109.032748] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Revised: 07/15/2009] [Indexed: 11/06/2022] Open
Abstract
The conformational dynamics of cytochrome P450 2B1 (CYP2B1) were investigated through the introduction of a disulfide bond to link the I- and K-helices by generation of a double Cys variant, Y309C/S360C. The consequences of the disulfide bonding were examined both experimentally and in silico by molecular dynamics simulations. Under high hydrostatic pressures, the partial inactivation volume for the Y309C/S360C variant was determined to be -21 cm3mol(-1), which is more than twice as much as those of the wild type (WT) and single Cys variants (Y309C, S360C). This result indicates that the engineered disulfide bond has substantially reduced the protein plasticity of the Y309C/S360C variant. Under steady-state turnover conditions, the S360C variant catalyzed the N-demethylation of benzphetamine and O-deethylation of 7-ethoxy-trifluoromethylcoumarin as the WT did, whereas the Y309C variant retained only 39% of the N-demethylation activity and 66% of the O-deethylation activity compared with the WT. Interestingly, the Y309C/S360C variant restored the N-demethylation activity to the same level as that of the WT but decreased the O-deethylation activity to only 19% of the WT. Furthermore, the Y309C/S360C variant showed increased substrate specificity for testosterone over androstenedione. Molecular dynamics simulations revealed that the engineered disulfide bond altered substrate access channels. Taken together, these results suggest that protein dynamics play an important role in regulating substrate entry and recognition.
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Affiliation(s)
- Haoming Zhang
- From the Department of Pharmacology, University of Michigan, Ann Arbor, Michigan 48109 and
| | - Cesar Kenaan
- From the Department of Pharmacology, University of Michigan, Ann Arbor, Michigan 48109 and
| | - Djemel Hamdane
- INSERM U779, 78 rue du Général Leclerc, 94275 Le Kremlin-Bicêtre, France
| | - Gaston Hui Bon Hoa
- INSERM U779, 78 rue du Général Leclerc, 94275 Le Kremlin-Bicêtre, France
| | - Paul F. Hollenberg
- From the Department of Pharmacology, University of Michigan, Ann Arbor, Michigan 48109 and
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Zhang H, Lin HL, Walker VJ, Hamdane D, Hollenberg PF. tert-Butylphenylacetylene is a potent mechanism-based inactivator of cytochrome P450 2B4: inhibition of cytochrome P450 catalysis by steric hindrance. Mol Pharmacol 2009; 76:1011-8. [PMID: 19720728 DOI: 10.1124/mol.109.059808] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We have demonstrated that 4-(tert-butyl)-phenylacetylene (tBPA) is a potent mechanism-based inactivator for cytochrome P450 2B4 (P450 2B4) in the reconstituted system. It inactivates P450 2B4 in a NADPH- and time-dependent manner with a K(I) of 0.44 microM and k(inact) of 0.12 min(-1). The partition ratio was approximately zero, indicating that inactivation occurs without the reactive intermediate leaving the active site. Liquid chromatography-mass spectrometry analyses revealed that tBPA forms a protein adduct with a 1:1 stoichiometry. Peptide mapping of the tBPA-modified protein provides evidence that tBPA is covalently bound to Thr302. This is consistent with results of molecular modeling that show the terminal carbon of the acetylenic group is only 3.65 A away from Thr302. To characterize the effect of covalent modification of Thr302, tBPA-modified P450 2B4 was purified to homogeneity from the reconstituted system. The Soret band of tBPA-modified protein is red-shifted by 5 to 422 nm compared with unmodified protein. Benzphetamine binding to the modified P450 2B4 causes no spin shift, indicating that substrate binding and/or the heme environment has been altered by covalently bound tBPA. Cytochrome P450 reductase reduces the unmodified and tBPA-modified P450s at approximately the same rate. However, addition of benzphetamine stimulates the rate of reduction of unmodified P450 2B4 by approximately 20-fold but only marginally stimulates reduction of the tBPA-modified protein. This large discrepancy in the stimulation of the first electron transfer by benzphetamine strongly suggests that the impairment of P450 catalysis is due to inhibition of benzphetamine binding to the tBPA-modified P450 2B4.
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Affiliation(s)
- Haoming Zhang
- Department of Pharmacology, The University of Michigan, Ann Arbor, MI 48109-5632, USA
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Hamdane D, Zhang H, Hollenberg P. Oxygen activation by cytochrome P450 monooxygenase. PHOTOSYNTHESIS RESEARCH 2008; 98:657-66. [PMID: 18600471 PMCID: PMC2743973 DOI: 10.1007/s11120-008-9322-1] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2008] [Accepted: 06/11/2008] [Indexed: 05/18/2023]
Abstract
Unlike photosystem II (PSII) that catalyzes formation of the O-O bond, the cytochromes P450 (P450), members of a superfamily of hemoproteins, catalyze the scission of the O-O bond of dioxygen molecules and insert a single oxygen atom into unactivated hydrocarbons through a hydrogen abstraction-oxygen rebound mechanism. Hydroxylation of the unactivated hydrocarbons at physiological temperatures is vital for many cellar processes such as the biosynthesis of many endogenous compounds and the detoxification of xenobiotics in humans and plants. Even though it carries out the opposite of the water splitting reaction, P450 may share similarities to PSII in proton delivery networks, oxygen and water access channels, and consecutive electron transfer processes. In this article, we review recent advances in understanding the molecular mechanisms by which P450 activates dioxygen.
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Affiliation(s)
- Djemel Hamdane
- Department of Pharmacology and Department of Anesthesiology, The University of Michigan, Ann Arbor, MI 48109, USA
| | - Haoming Zhang
- Department of Pharmacology and Department of Anesthesiology, The University of Michigan, Ann Arbor, MI 48109, USA
| | - Paul Hollenberg
- Department of Pharmacology and Department of Anesthesiology, The University of Michigan, Ann Arbor, MI 48109, USA
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Finn RD, McLaughlin LA, Ronseaux S, Rosewell I, Houston JB, Henderson CJ, Wolf CR. Defining the in Vivo Role for cytochrome b5 in cytochrome P450 function through the conditional hepatic deletion of microsomal cytochrome b5. J Biol Chem 2008; 283:31385-93. [PMID: 18805792 PMCID: PMC2581580 DOI: 10.1074/jbc.m803496200] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
In vitro, cytochrome b5 modulates the rate of
cytochrome P450-dependent mono-oxygenation reactions. However, the role of
this enzyme in determining drug pharmacokinetics in vivo and the
consequential effects on drug absorption distribution, metabolism, excretion,
and toxicity are unclear. In order to resolve this issue, we have carried out
the conditional deletion of microsomal cytochrome b5 in
the liver to create the hepatic microsomal cytochrome b5
null mouse. These mice develop and breed normally and have no overt phenotype.
In vitro studies using a range of substrates for different P450
enzymes showed that in hepatic microsomal cytochrome b5
null NADH-mediated metabolism was essentially abolished for most substrates,
and the NADPH-dependent metabolism of many substrates was reduced by
50–90%. This reduction in metabolism was also reflected in the in
vivo elimination profiles of several drugs, including midazolam,
metoprolol, and tolbutamide. In the case of chlorzoxazone, elimination was
essentially unchanged. For some drugs, the pharmacokinetics were also markedly
altered; for example, when administered orally, the maximum plasma
concentration for midazolam was increased by 2.5-fold, and the clearance
decreased by 3.6-fold in hepatic microsomal cytochrome b5
null mice. These data indicate that microsomal cytochrome
b5 can play a major role in the in vivo
metabolism of certain drugs and chemicals but in a P450- and
substrate-dependent manner.
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Affiliation(s)
- Robert D Finn
- Cancer Research UK Molecular Pharmacology Unit, Biomedical Research Institute, Level 5, Ninewells Hospital and Medical School, Dundee DD1 9SY, United Kingdom
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