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Roberts AG, Stevens JC, Szklarz GD, Scott EE, Kumar S, Shah MB, Halpert JR. Four Decades of Cytochrome P450 2B Research: From Protein Adducts to Protein Structures and Beyond. Drug Metab Dispos 2023; 51:111-122. [PMID: 36310033 PMCID: PMC11022898 DOI: 10.1124/dmd.122.001109] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 10/18/2022] [Accepted: 10/20/2022] [Indexed: 01/03/2023] Open
Abstract
This article features selected findings from the senior author and colleagues dating back to 1978 and covering approximately three-fourths of the 60 years since the discovery of cytochrome P450. Considering the vast number of P450 enzymes in this amazing superfamily and their importance for so many fields of science and medicine, including drug design and development, drug therapy, environmental health, and biotechnology, a comprehensive review of even a single topic is daunting. To make a meaningful contribution to the 50th anniversary of Drug Metabolism and Disposition, we trace the development of the research in a single P450 laboratory through the eyes of seven individuals with different backgrounds, perspectives, and subsequent career trajectories. All co-authors are united in their fascination for the structural basis of mammalian P450 substrate and inhibitor selectivity and using such information to improve drug design and therapy. An underlying theme is how technological advances enable scientific discoveries that were impossible and even inconceivable to prior generations. The work performed spans the continuum from: 1) purification of P450 enzymes from animal tissues to purification of expressed human P450 enzymes and their site-directed mutants from bacteria; 2) inhibition, metabolism, and spectral studies to isothermal titration calorimetry, deuterium exchange mass spectrometry, and NMR; 3) homology models based on bacterial P450 X-ray crystal structures to rabbit and human P450 structures in complex with a wide variety of ligands. Our hope is that humanizing the scientific endeavor will encourage new generations of scientists to make fundamental new discoveries in the P450 field. SIGNIFICANCE STATEMENT: The manuscript summarizes four decades of work from Dr. James Halpert's laboratory, whose investigations have shaped the cytochrome P450 field, and provides insightful perspectives of the co-authors. This work will also inspire future drug metabolism scientists to make critical new discoveries in the cytochrome P450 field.
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Affiliation(s)
- Arthur G Roberts
- Pharmaceutical and Biomedical Sciences Department, University of Georgia, 240 W. Green St., Athens, Georgia (A.G.R.); Unaffiliated (J.C.S.); Department of Pharmaceutical Sciences, West Virginia University, Morgantown, West Virginia (G.D.S.); Departments of Medicinal Chemistry, Pharmacology, and Biological Chemistry and the Program in Biophysics, University of Michigan, Ann Arbor, Michigan (E.E.S.); Department of Pharmaceutical Sciences, The University of Tennessee Health Science Center, Memphis, Tennessee (S.K.); Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York (M.B.S.); Department of Pharmacology and Toxicology, University of Arizona, 1703 E. Mabel Street, P.O. Box 210207, Tucson, Arizona (J.R.H.).
| | - Jeffrey C Stevens
- Pharmaceutical and Biomedical Sciences Department, University of Georgia, 240 W. Green St., Athens, Georgia (A.G.R.); Unaffiliated (J.C.S.); Department of Pharmaceutical Sciences, West Virginia University, Morgantown, West Virginia (G.D.S.); Departments of Medicinal Chemistry, Pharmacology, and Biological Chemistry and the Program in Biophysics, University of Michigan, Ann Arbor, Michigan (E.E.S.); Department of Pharmaceutical Sciences, The University of Tennessee Health Science Center, Memphis, Tennessee (S.K.); Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York (M.B.S.); Department of Pharmacology and Toxicology, University of Arizona, 1703 E. Mabel Street, P.O. Box 210207, Tucson, Arizona (J.R.H.)
| | - Grazyna D Szklarz
- Pharmaceutical and Biomedical Sciences Department, University of Georgia, 240 W. Green St., Athens, Georgia (A.G.R.); Unaffiliated (J.C.S.); Department of Pharmaceutical Sciences, West Virginia University, Morgantown, West Virginia (G.D.S.); Departments of Medicinal Chemistry, Pharmacology, and Biological Chemistry and the Program in Biophysics, University of Michigan, Ann Arbor, Michigan (E.E.S.); Department of Pharmaceutical Sciences, The University of Tennessee Health Science Center, Memphis, Tennessee (S.K.); Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York (M.B.S.); Department of Pharmacology and Toxicology, University of Arizona, 1703 E. Mabel Street, P.O. Box 210207, Tucson, Arizona (J.R.H.)
| | - Emily E Scott
- Pharmaceutical and Biomedical Sciences Department, University of Georgia, 240 W. Green St., Athens, Georgia (A.G.R.); Unaffiliated (J.C.S.); Department of Pharmaceutical Sciences, West Virginia University, Morgantown, West Virginia (G.D.S.); Departments of Medicinal Chemistry, Pharmacology, and Biological Chemistry and the Program in Biophysics, University of Michigan, Ann Arbor, Michigan (E.E.S.); Department of Pharmaceutical Sciences, The University of Tennessee Health Science Center, Memphis, Tennessee (S.K.); Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York (M.B.S.); Department of Pharmacology and Toxicology, University of Arizona, 1703 E. Mabel Street, P.O. Box 210207, Tucson, Arizona (J.R.H.)
| | - Santosh Kumar
- Pharmaceutical and Biomedical Sciences Department, University of Georgia, 240 W. Green St., Athens, Georgia (A.G.R.); Unaffiliated (J.C.S.); Department of Pharmaceutical Sciences, West Virginia University, Morgantown, West Virginia (G.D.S.); Departments of Medicinal Chemistry, Pharmacology, and Biological Chemistry and the Program in Biophysics, University of Michigan, Ann Arbor, Michigan (E.E.S.); Department of Pharmaceutical Sciences, The University of Tennessee Health Science Center, Memphis, Tennessee (S.K.); Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York (M.B.S.); Department of Pharmacology and Toxicology, University of Arizona, 1703 E. Mabel Street, P.O. Box 210207, Tucson, Arizona (J.R.H.)
| | - Manish B Shah
- Pharmaceutical and Biomedical Sciences Department, University of Georgia, 240 W. Green St., Athens, Georgia (A.G.R.); Unaffiliated (J.C.S.); Department of Pharmaceutical Sciences, West Virginia University, Morgantown, West Virginia (G.D.S.); Departments of Medicinal Chemistry, Pharmacology, and Biological Chemistry and the Program in Biophysics, University of Michigan, Ann Arbor, Michigan (E.E.S.); Department of Pharmaceutical Sciences, The University of Tennessee Health Science Center, Memphis, Tennessee (S.K.); Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York (M.B.S.); Department of Pharmacology and Toxicology, University of Arizona, 1703 E. Mabel Street, P.O. Box 210207, Tucson, Arizona (J.R.H.)
| | - James R Halpert
- Pharmaceutical and Biomedical Sciences Department, University of Georgia, 240 W. Green St., Athens, Georgia (A.G.R.); Unaffiliated (J.C.S.); Department of Pharmaceutical Sciences, West Virginia University, Morgantown, West Virginia (G.D.S.); Departments of Medicinal Chemistry, Pharmacology, and Biological Chemistry and the Program in Biophysics, University of Michigan, Ann Arbor, Michigan (E.E.S.); Department of Pharmaceutical Sciences, The University of Tennessee Health Science Center, Memphis, Tennessee (S.K.); Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Albany, New York (M.B.S.); Department of Pharmacology and Toxicology, University of Arizona, 1703 E. Mabel Street, P.O. Box 210207, Tucson, Arizona (J.R.H.)
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Skopec MM, Halpert JR, Dearing MD. Mammalian cytochrome P450 biodiversity: Physiological importance, function, and protein and genomic structures of cytochromes P4502B in multiple species of woodrats with different dietary preferences. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2022; 95:107-129. [PMID: 35953153 DOI: 10.1016/bs.apha.2022.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The vast diversity of cytochrome P450 enzymes in mammals has been proposed to result in large measure from plant-animal warfare, whereby evolution of chemical defenses such as phenolics and terpenoids in plants led to duplication and divergence of P450 genes in herbivores. Over evolutionary time, natural selection is predicted to have produced P450s with high affinity and enhanced metabolism of substrates that are ingested regularly by herbivores. Interestingly, however, almost all knowledge of the interactions of mammalian P450 enzymes with substrates stems from studies of the metabolism of drugs and model compounds rather than studies on wild mammalian herbivores and their respective PSMs. A question of particular interest centers on the role of individual P450 enzymes in the ability of certain herbivores to specialize on plants that are lethal to most other species, including those from the same genus as the specialists. We tackled this intricate problem using a tractable natural system (herbivorous woodrats, genus Neotoma) focusing on comparisons of the specialist N. stephensi, the facultative specialist N. lepida, and the generalist N. albigula, and employing a cross-disciplinary approach involving ecology, biochemistry, pharmacology, structural biology, and genomics. Based on multiple findings suggesting the importance of CYP2B enzymes for ingestion of juniper and a major constituent, α-pinene, we characterized the structure, function and activity of several CYP2B enzymes in woodrats with different dietary habits. Results to date suggest that differences in CYP2B gene copy number may contribute to differential tolerance of PSMs among woodrat species, although additional work is warranted to firmly link gene copy number to juniper tolerance.
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Affiliation(s)
- Michele M Skopec
- Department of Zoology, Weber State University, Ogden, UT, United States
| | - James R Halpert
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, AZ, United States.
| | - M Denise Dearing
- School of Biological Sciences, University of Utah, Salt Lake City, UT, United States.
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Chen C, Liu J, Halpert JR, Wilderman PR. Use of Phenoxyaniline Analogues To Generate Biochemical Insights into the Interactio n of Polybrominated Diphenyl Ether with CYP2B Enzymes. Biochemistry 2018; 57:817-826. [PMID: 29215266 DOI: 10.1021/acs.biochem.7b01024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Human hepatic cytochromes P450 (CYP) are integral to xenobiotic metabolism. CYP2B6 is a major catalyst of biotransformation of environmental toxicants, including polybrominated diphenyl ethers (PBDEs). CYP2B substrates tend to contain halogen atoms, but the biochemical basis for this selectivity and for species specific determinants of metabolism has not been identified. Spectral binding titrations and inhibition studies were performed to investigate interactions of rat CYP2B1, rabbit CYP2B4, and CYP2B6 with a series of phenoxyaniline (POA) congeners that are analogues of PBDEs. For most congeners, there was a <3-fold difference between the spectral binding constants (KS) and IC50 values. In contrast, large discrepancies between these values were observed for POA and 3-chloro-4-phenoxyaniline. CYP2B1 was the enzyme most sensitive to POA congeners, so the Val-363 residue from that enzyme was introduced into CYP2B4 or CYP2B6. This substitution partially altered the protein-ligand interaction profiles to make them more similar to that of CYP2B1. Addition of cytochrome P450 oxidoreductase (POR) to titrations of CYP2B6 with POA or 2'4'5'TCPOA decreased the affinity of both ligands for the enzyme. Addition of cytochrome b5 to a recombinant enzyme system containing POR and CYP2B6 increased the POA IC50 value and decreased the 2'4'5'TCPOA IC50 value. Overall, the inconsistency between KS and IC50 values for POA versus 2'4'5'TCPOA is largely due to the effects of redox partner binding. These results provide insight into the biochemical basis of binding of diphenyl ethers to human CYP2B6 and changes in CYP2B6-mediated metabolism that are dependent on POA congener and redox partner identity.
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Affiliation(s)
- Chao Chen
- University of Connecticut School of Pharmacy , Storrs, Connecticut 06269, United States
| | - Jingbao Liu
- University of Connecticut School of Pharmacy , Storrs, Connecticut 06269, United States
| | - James R Halpert
- University of Connecticut School of Pharmacy , Storrs, Connecticut 06269, United States
| | - P Ross Wilderman
- University of Connecticut School of Pharmacy , Storrs, Connecticut 06269, United States
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