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Sevrioukova IF. Interaction of CYP3A4 with the inhibitor cobicistat: Structural and mechanistic insights and comparison with ritonavir. Arch Biochem Biophys 2024; 758:110071. [PMID: 38909836 DOI: 10.1016/j.abb.2024.110071] [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: 04/17/2024] [Revised: 06/20/2024] [Accepted: 06/21/2024] [Indexed: 06/25/2024]
Abstract
Cobicistat is a derivative of ritonavir marketed as a pharmacoenhancer for anti-HIV therapy. This study investigated the interaction of cobicistat with the target protein, drug-metabolizing cytochrome P450 3A4 (CYP3A4), at the molecular level using spectral, kinetic, functional, and structural approaches. It was found that, similar to ritonavir, cobicistat directly coordinates to the heme via the thiazole nitrogen but its affinity and the binding rate are 2-fold lower: 0.030 μM and 0.72 s-1, respectively. The newly determined 2.5 Å crystal structure of cobicistat-bound CYP3A4 suggests that these changes arise from the inability of cobicistat to H-bond to the active site S119 and establish multiple stabilizing contacts with the F-F' connecting fragment, which becomes disordered upon steric clashing with the bulky morpholine moiety. Nonetheless, cobicistat inhibits recombinant CYP3A4 as potently as ritonavir (IC50 of 0.24 μM vs 0.22 μM, respectively) due to strong ligation to the heme and formation of extensive hydrophobic/aromatic interactions via the phenyl side-groups. To get insights into the inhibitory mechanism, the K257 residue, known to be solely and irreversibly modified by the reactive ritonavir metabolite, was substituted with alanine. Neither this nor control K266A mutation changed the extent of time-dependent inhibition of CYP3A4 by cobicistat and ritonavir, suggesting the existence of alternative inactivation mechanism(s). More importantly, K257 was found to be functionally important and contributed to CYP3A4 allosterism, possibly by modulating protein-ligand interactions through conformational dynamics.
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Affiliation(s)
- Irina F Sevrioukova
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA, 92697-3900, USA.
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2
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Oladipo SD, Zamisa SJ, Badeji AA, Ejalonibu MA, Adeleke AA, Lawal IA, Henni A, Lawal MM. Ni 2+ and Cu 2+ complexes of N-(2,6-dichlorophenyl)-N-mesityl formamidine dithiocarbamate structural and functional properties as CYP3A4 potential substrates. Sci Rep 2023; 13:13414. [PMID: 37591990 PMCID: PMC10435461 DOI: 10.1038/s41598-023-39502-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 07/26/2023] [Indexed: 08/19/2023] Open
Abstract
Metal compounds continued to attract diverse applications due to their malleability in several capacities. In this study, we present our findings on the crystal structures and functional properties of Ni2+ and Cu2+ complexes of N'-(2,6-dichlorophenyl)-N-mesitylformamidine dithiocarbamate (L) comprising [Ni-(L)2] (1) and [Cu-(L)2] (2) with a four-coordinate metal center. We established the two complex structures through 1H and 13C nuclear magnetic resonance (NMR), elemental, and single-crystal X-ray analysis. The analyses showed that the two complexes are isomorphous, having P21/c as a space group and a unit-cell similarity index (π) of 0.002. The two complexes conform to a distorted square planar geometry around the metal centers. The calculated and experimental data, including bond lengths, angles, and NMR values, are similar. Hirshfeld surface analysis revealed the variational contribution of the different types of intermolecular contacts driven by the crystal lattice of the two solvated complexes. Our knowledge of the potential biological implication of these structures enabled us to probe the compounds as prospective CYP3A4 inhibitors. This approach mimics current trends in pharmaceutical design and biomedicine by incorporating potentially active molecules into various media to predict their biological efficacies. The simulations show appreciable binding of compounds 1 and 2 to CYP3A4 with average interaction energies of -97 and -87 kcal/mol, respectively. The protein attains at least five conformational states in the three studied models using a Gaussian Mixture Model-based clustering and free energy prediction. Electric field analysis shows the crucial residues to substrate binding at the active site, enabling CYP3A4 structure to function prediction. The predicted inhibition with these Ni2+ and Cu2+ complexes indicates that CYP3A4 overexpression in a diseased state like cancer would reduce, thereby increasing the chemotherapeutic compounds' shelf-lives for adsorption. This multidimensional study addresses various aspects of molecular metal electronics, including their application as substrate-mimicking inhibitors. The outcome would enable further research on bio-metal compounds of critical potential.
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Affiliation(s)
- Segun D Oladipo
- Department of Chemical Sciences, Olabisi Onabanjo University, P.M.B 2002, Ago-Iwoye, Nigeria.
- School of Chemistry and Physics, Westville Campus, University of KwaZulu-Natal, Private Bag X54001, Durban, 4000, South Africa.
| | - Sizwe J Zamisa
- School of Chemistry and Physics, Westville Campus, University of KwaZulu-Natal, Private Bag X54001, Durban, 4000, South Africa
| | - Abosede A Badeji
- Department of Chemical Sciences, Tai Solarin University of Education, Ogun State, Ijagun, Nigeria
| | - Murtala A Ejalonibu
- Discipline of Medical Biochemistry, School of Laboratory Medicine and Medical Sciences, University of KwaZulu-Natal, Private Bag X54001, Durban, 4000, South Africa
| | - Adesola A Adeleke
- Department of Chemical Sciences, Olabisi Onabanjo University, P.M.B 2002, Ago-Iwoye, Nigeria
| | - Isiaka A Lawal
- Faculty of Engineering and Applied Science, University of Regina, 3737 Wascana Parkway, Regina, SK, S4S 0A2, Canada
| | - Amr Henni
- Faculty of Engineering and Applied Science, University of Regina, 3737 Wascana Parkway, Regina, SK, S4S 0A2, Canada
| | - Monsurat M Lawal
- Discipline of Medical Biochemistry, School of Laboratory Medicine and Medical Sciences, University of KwaZulu-Natal, Private Bag X54001, Durban, 4000, South Africa.
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3
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Mohamed H, Ghith A, Bell SG. The binding of nitrogen-donor ligands to the ferric and ferrous forms of cytochrome P450 enzymes. J Inorg Biochem 2023; 242:112168. [PMID: 36870164 DOI: 10.1016/j.jinorgbio.2023.112168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 01/24/2023] [Accepted: 02/21/2023] [Indexed: 02/27/2023]
Abstract
The cytochrome P450 superfamily of heme-thiolate monooxygenase enzymes can catalyse various oxidation reactions. The addition of a substrate or an inhibitor ligand induces changes in the absorption spectrum of these enzymes and UV-visible (UV-vis) absorbance spectroscopy is the most common and readily available technique used to interrogate their heme and active site environment. Nitrogen-containing ligands can inhibit the catalytic cycle of heme enzymes by interacting with the heme. Here we evaluate the binding of imidazole and pyridine-based ligands to the ferric and ferrous forms of a selection of bacterial cytochrome P450 enzymes using UV-visible absorbance spectroscopy. The majority of these ligands interact with the heme as one would expect for type II nitrogen directly coordinated to a ferric heme-thiolate species. However, the spectroscopic changes observed in the ligand-bound ferrous forms indicated differences in the heme environment across these P450 enzyme/ligand combinations. Multiple species were observed in the UV-vis spectra of the ferrous ligand-bound P450s. None of the enzymes gave rise to the isolation of a single species with a Soret band at ∼442-447 nm, indicative of a 6-coordinate ferrous thiolate species with a nitrogen-donor ligand. A ferrous species with Soret band at ∼427 nm coupled with an α-band of increased intensity was observed with the imidazole ligands. With some enzyme-ligand combinations reduction resulted in breaking of the iron‑nitrogen bond yielding a 5-coordinate high-spin ferrous species. In other instances, the ferrous form was readily oxidised back to the ferric form on addition of the ligand.
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Affiliation(s)
- Hebatalla Mohamed
- Department of Chemistry, University Adelaide, Adelaide, SA 5005, Australia
| | - Amna Ghith
- Department of Chemistry, University Adelaide, Adelaide, SA 5005, Australia
| | - Stephen G Bell
- Department of Chemistry, University Adelaide, Adelaide, SA 5005, Australia.
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4
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Interaction of CYP3A4 with Rationally Designed Ritonavir Analogues: Impact of Steric Constraints Imposed on the Heme-Ligating Group and the End-Pyridine Attachment. Int J Mol Sci 2022; 23:ijms23137291. [PMID: 35806297 PMCID: PMC9266530 DOI: 10.3390/ijms23137291] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 06/27/2022] [Accepted: 06/28/2022] [Indexed: 02/04/2023] Open
Abstract
Controlled inhibition of drug-metabolizing cytochrome P450 3A4 (CYP3A4) is utilized to boost bioavailability of anti-viral and immunosuppressant pharmaceuticals. We investigate structure–activity relationships (SARs) in analogues of ritonavir, a potent CYP3A4 inhibitor marketed as pharmacoenhancer, to determine structural elements required for potent inhibition and whether the inhibitory potency can be further improved via a rational structure-based design. This study investigated eight (series VI) inhibitors differing in head- and end-moieties and their respective linkers. SAR analysis revealed the multifactorial regulation of inhibitory strength, with steric constraints imposed on the tethered heme-ligating moiety being a key factor. Minimization of these constraints by changing the linkers’ length/flexibility and N-heteroatom position strengthened heme coordination and markedly improved binding and/or inhibitory strength. Impact of the end-pyridine attachment was not uniform due to influence of other determinants controlling the ligand-binding mode. This interplay between pharmacophoric determinants and the end-group enlargement can be used for further inhibitor optimization.
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Podgorski MN, Coleman T, Giang PD, Wang CR, Bruning JB, Bernhardt PV, De Voss JJ, Bell SG. To Be, or Not to Be, an Inhibitor: A Comparison of Azole Interactions with and Oxidation by a Cytochrome P450 Enzyme. Inorg Chem 2021; 61:236-245. [PMID: 34910500 DOI: 10.1021/acs.inorgchem.1c02786] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The cytochrome P450 (CYP) superfamily of heme monooxygenases is involved in a range of important chemical biotransformations across nature. Azole-containing molecules have been developed as drugs that bind to the heme center of these enzymes, inhibiting their function. The optical spectrum of CYP enzymes after the addition of these inhibitors is used to assess how the molecules bind. Here we use the bacterial CYP199A4 enzyme, from Rhodopseudomonas palustris HaA2, to compare how imidazolyl and triazolyl inhibitors bind to ferric and ferrous heme. 4-(Imidazol-1-yl)benzoic acid induced a red shift in the Soret wavelength (424 nm) in the ferric enzyme along with an increase and a decrease in the intensities of the δ and α bands, respectively. 4-(1H-1,2,4-Triazol-1-yl)benzoic acid binds to CYP199A4 with a 10-fold lower affinity and induces a smaller red shift in the Soret band. The crystal structures of CYP199A4 with these two inhibitors confirmed that these differences in the optical spectra were due to coordination of the imidazolyl ligand to the ferric Fe, but the triazolyl inhibitor interacts with, rather than displaces, the ferric aqua ligand. Additional water molecules were present in the active site of 4-(1H-1,2,4-triazol-1-yl)benzoic acid-bound CYP199A4. The space required to accommodate these additional water molecules in the active site necessitates changes in the position of the hydrophobic phenylalanine 298 residue. Upon reduction of the heme, the imidazole-based inhibitor Fe-N ligation was not retained. A 5-coordinate heme was also the predominant species in 4-(1H-1,2,4-triazol-1-yl)benzoic acid-bound ferrous CYP199A4, but there was an obvious shoulder at 447 nm indicative of some degree of Fe-N coordination. Rather than inhibit CYP199A4, 4-(imidazol-1-yl)benzoic acid was a substrate and was oxidized to generate a metabolite derived from ring opening of the imidazolyl ring: 4-[[2-(formylamino)acetyl]amino]benzoic acid.
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Affiliation(s)
- Matthew N Podgorski
- Department of Chemistry, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Tom Coleman
- Department of Chemistry, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Peter D Giang
- School of Chemistry and Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia
| | - C Ruth Wang
- Department of Chemistry, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - John B Bruning
- School of Biological Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Paul V Bernhardt
- School of Chemistry and Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia
| | - James J De Voss
- School of Chemistry and Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Stephen G Bell
- Department of Chemistry, University of Adelaide, Adelaide, South Australia 5005, Australia
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6
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Campomizzi CS, Ghanatios GE, Estrada DF. 19F-NMR reveals substrate specificity of CYP121A1 in Mycobacterium tuberculosis. J Biol Chem 2021; 297:101287. [PMID: 34634307 PMCID: PMC8571521 DOI: 10.1016/j.jbc.2021.101287] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 10/04/2021] [Accepted: 10/06/2021] [Indexed: 01/10/2023] Open
Abstract
Cytochromes P450 are versatile enzymes that function in endobiotic and xenobiotic metabolism and undergo meaningful structural changes that relate to their function. However, the way in which conformational changes inform the specific recognition of the substrate is often unknown. Here, we demonstrate the utility of fluorine (19F)-NMR spectroscopy to monitor structural changes in CYP121A1, an essential enzyme from Mycobacterium tuberculosis. CYP121A1 forms functional dimers that catalyze the phenol-coupling reaction of the dipeptide dicyclotyrosine. The thiol-reactive compound 3-bromo-1,1,1-trifluoroacetone was used to label an S171C mutation of the enzyme FG loop, which is located adjacent to the homodimer interface. Substrate titrations and inhibitor-bound 19F-NMR spectra indicate that ligand binding reduces conformational heterogeneity at the FG loop in both the dimer and in an engineered monomer of CYP121A1. However, only the dimer was found to promote a substrate-bound conformation that was preexisting in the substrate-free spectra, thus confirming a role for the dimer interface in dicyclotyrosine recognition. Moreover, 19F-NMR spectra in the presence of substrate analogs indicate the hydrogen-bonding feature of the dipeptide aromatic side chain as a dicyclotyrosine specificity criterion. This study demonstrates the utility of 19F-NMR as applied to a multimeric cytochrome P450, while also revealing mechanistic insights for an essential M. tuberculosis enzyme.
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Affiliation(s)
- Christopher S Campomizzi
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Science, University at Buffalo, Buffalo, New York, USA
| | - George E Ghanatios
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Science, University at Buffalo, Buffalo, New York, USA
| | - D Fernando Estrada
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Science, University at Buffalo, Buffalo, New York, USA.
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7
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Ducharme J, Sevrioukova IF, Thibodeaux CJ, Auclair K. Structural Dynamics of Cytochrome P450 3A4 in the Presence of Substrates and Cytochrome P450 Reductase. Biochemistry 2021; 60:2259-2271. [PMID: 34196520 DOI: 10.1021/acs.biochem.1c00178] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cytochrome P450 3A4 (CYP3A4) is the most important drug-metabolizing enzyme in humans and has been associated with harmful drug interactions. The activity of CYP3A4 is known to be modulated by several compounds and by the electron transfer partner, cytochrome P450 reductase (CPR). The underlying mechanism of these effects, however, is poorly understood. We have used hydrogen-deuterium exchange mass spectrometry to investigate the impact of binding of CPR and of three different substrates (7-benzyloxy-4-trifluoromethyl-coumarin, testosterone, and progesterone) on the conformational dynamics of CYP3A4. Here, we report that interaction of CYP3A4 with substrates or with the oxidized or reduced forms of CPR leads to a global rigidification of the CYP3A4 structure. This was evident from the suppression of deuterium exchange in several regions of CYP3A4, including regions known to be involved in protein-protein interactions (helix C) and substrate binding and specificity (helices B' and E, and loop K/β1). Furthermore, the bimodal isotopic distributions observed for some CYP3A4-derived peptides were drastically impacted upon binding to CPR and/or substrates, suggesting the existence of stable CYP3A4 conformational populations that are perturbed by ligand/CPR binding. The results have implications for understanding the mechanisms of ligand binding, allostery, and catalysis in CYP enzymes.
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Affiliation(s)
- Julie Ducharme
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec, Canada H3A 0B8
| | - Irina F Sevrioukova
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697, United States
| | - Christopher J Thibodeaux
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec, Canada H3A 0B8
| | - Karine Auclair
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec, Canada H3A 0B8
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8
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Ducharme J, Polic V, Thibodeaux CJ, Auclair K. Combining Small-Molecule Bioconjugation and Hydrogen-Deuterium Exchange Mass Spectrometry (HDX-MS) to Expose Allostery: the Case of Human Cytochrome P450 3A4. ACS Chem Biol 2021; 16:882-890. [PMID: 33913317 DOI: 10.1021/acschembio.1c00084] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
We report a novel approach to study allostery which combines the use of carefully selected bioconjugates and hydrogen-deuterium exchange mass spectrometry (HDX-MS). This strategy avoids issues related to weak substrate binding and ligand relocalization. The utility of our method is demonstrated using human cytochrome P450 3A4 (CYP3A4), the most important drug-metabolizing enzyme. Allosteric activation and inhibition of CYP3A4 by pharmaceuticals is an important mechanism of drug interactions. We performed HDX-MS analysis on several CYP3A4-effector bioconjugates, some of which mimic the allosteric effect of positive effectors, while others show activity enhancement even though the label does not occupy the allosteric pocket (agonistic) or do not show activation while still blocking the allosteric site (antagonistic). This allowed us to better define the position of the allosteric site, the protein structural dynamics associated with allosteric activation, and the presence of coexisting conformers.
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Affiliation(s)
- Julie Ducharme
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montréal, Québec, Canada H3A 0B8
| | - Vanja Polic
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montréal, Québec, Canada H3A 0B8
| | - Christopher J. Thibodeaux
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montréal, Québec, Canada H3A 0B8
| | - Karine Auclair
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montréal, Québec, Canada H3A 0B8
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9
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Wort JL, Ackermann K, Norman DG, Bode BE. A general model to optimise Cu II labelling efficiency of double-histidine motifs for pulse dipolar EPR applications. Phys Chem Chem Phys 2021; 23:3810-3819. [PMID: 33533341 DOI: 10.1039/d0cp06196d] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Electron paramagnetic resonance (EPR) distance measurements are making increasingly important contributions to studies of biomolecules underpinning health and disease by providing highly accurate and precise geometric constraints. Combining double-histidine (dH) motifs with CuII spin labels shows promise for further increasing the precision of distance measurements, and for investigating subtle conformational changes. However, non-covalent coordination-based spin labelling is vulnerable to low binding affinity. Dissociation constants of dH motifs for CuII-nitrilotriacetic acid were previously investigated via relaxation induced dipolar modulation enhancement (RIDME), and demonstrated the feasibility of exploiting the dH motif for EPR applications at sub-μM protein concentrations. Herein, the feasibility of using modulation depth quantitation in CuII-CuII RIDME to simultaneously estimate a pair of non-identical independent KD values in such a tetra-histidine model protein is addressed. Furthermore, we develop a general speciation model to optimise CuII labelling efficiency, depending upon pairs of identical or disparate KD values and total CuII label concentration. We find the dissociation constant estimates are in excellent agreement with previously determined values, and empirical modulation depths support the proposed model.
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Affiliation(s)
- Joshua L Wort
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex, and Centre of Magnetic Resonance, University of St Andrews North Haugh, St Andrews KY16 9ST, UK.
| | - Katrin Ackermann
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex, and Centre of Magnetic Resonance, University of St Andrews North Haugh, St Andrews KY16 9ST, UK.
| | - David G Norman
- School of Life Sciences, University of Dundee, Medical Sciences Institute, Dundee, DD1 5EH, UK
| | - Bela E Bode
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex, and Centre of Magnetic Resonance, University of St Andrews North Haugh, St Andrews KY16 9ST, UK.
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10
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Guengerich FP, McCarty KD, Chapman JG. Kinetics of cytochrome P450 3A4 inhibition by heterocyclic drugs defines a general sequential multistep binding process. J Biol Chem 2021; 296:100223. [PMID: 33449875 PMCID: PMC7948456 DOI: 10.1074/jbc.ra120.016855] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 12/16/2020] [Accepted: 12/21/2020] [Indexed: 11/21/2022] Open
Abstract
Cytochrome P450 (P450) 3A4 is the enzyme most involved in the metabolism of drugs and can also oxidize numerous steroids. This enzyme is also involved in one-half of pharmacokinetic drug-drug interactions, but details of the exact mechanisms of P450 3A4 inhibition are still unclear in many cases. Ketoconazole, clotrimazole, ritonavir, indinavir, and itraconazole are strong inhibitors; analysis of the kinetics of reversal of inhibition with the model substrate 7-benzoyl quinoline showed lag phases in several cases, consistent with multiple structures of P450 3A4 inhibitor complexes. Lags in the onset of inhibition were observed when inhibitors were added to P450 3A4 in 7-benzoyl quinoline O-debenzylation reactions, and similar patterns were observed for inhibition of testosterone 6β-hydroxylation by ritonavir and indinavir. Upon mixing with inhibitors, P450 3A4 showed rapid binding as judged by a spectral shift with at least partial high-spin iron character, followed by a slower conversion to a low-spin iron-nitrogen complex. The changes were best described by two intermediate complexes, one being a partial high-spin form and the second another intermediate, with half-lives of seconds. The kinetics could be modeled in a system involving initial loose binding of inhibitor, followed by a slow step leading to a tighter complex on a multisecond time scale. Although some more complex possibilities cannot be dismissed, these results describe a system in which conformationally distinct forms of P450 3A4 bind inhibitors rapidly and two distinct P450-inhibitor complexes exist en route to the final enzyme-inhibitor complex with full inhibitory activity.
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Affiliation(s)
- F Peter Guengerich
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.
| | - Kevin D McCarty
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Jesse G Chapman
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
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11
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Shi X, Chuo SW, Liou SH, Goodin DB. Double Electron–Electron Resonance Shows That the Substrate but Not the Inhibitors Causes Disorder in the F/G Loop of CYP119 in Solution. Biochemistry 2020; 59:1823-1831. [DOI: 10.1021/acs.biochem.0c00171] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Xiaoxiao Shi
- Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616, United States
- Department of Plant Sciences, University of California, One Shields Avenue, Davis, California 95616, United States
| | - Shih-Wei Chuo
- Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616, United States
| | - Shu-Hao Liou
- Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616, United States
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461, United States
| | - David B. Goodin
- Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616, United States
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12
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Podgorski MN, Harbort JS, Coleman T, Stok JE, Yorke JA, Wong LL, Bruning JB, Bernhardt PV, De Voss JJ, Harmer JR, Bell SG. Biophysical Techniques for Distinguishing Ligand Binding Modes in Cytochrome P450 Monooxygenases. Biochemistry 2020; 59:1038-1050. [PMID: 32058707 DOI: 10.1021/acs.biochem.0c00027] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The cytochrome P450 superfamily of heme monooxygenases catalyzes important chemical reactions across nature. The changes in the optical spectra of these enzymes, induced by the addition of substrates or inhibitors, are critical for assessing how these molecules bind to the P450, enhancing or inhibiting the catalytic cycle. Here we use the bacterial CYP199A4 enzyme (Uniprot entry Q2IUO2), from Rhodopseudomonas palustris HaA2, and a range of substituted benzoic acids to investigate different binding modes. 4-Methoxybenzoic acid elicits an archetypal type I spectral response due to a ≥95% switch from the low- to high-spin state with concomitant dissociation of the sixth aqua ligand. 4-(Pyridin-3-yl)- and 4-(pyridin-2-yl)benzoic acid induced different type II ultraviolet-visible (UV-vis) spectral responses in CYP199A4. The former induced a greater red shift in the Soret wavelength (424 nm vs 422 nm) along with a larger overall absorbance change and other differences in the α-, β-, and δ-bands. There were also variations in the ferrous UV-vis spectra of these two substrate-bound forms with a spectrum indicative of Fe-N bond formation with 4-(pyridin-3-yl)benzoic acid. The crystal structures of CYP199A4, with the pyridinyl compounds bound, revealed that while the nitrogen of 4-(pyridin-3-yl)benzoic acid is coordinated to the heme, with 4-(pyridin-2-yl)benzoic acid an aqua ligand remains. Continuous wave and pulse electron paramagnetic resonance data in frozen solution revealed that the substrates are bound in the active site in a form consistent with the crystal structures. The redox potential of each CYP199A4-substrate combination was measured, allowing correlation among binding modes, spectroscopic properties, and the observed biochemical activity.
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Affiliation(s)
- Matthew N Podgorski
- Department of Chemistry, University of Adelaide, Adelaide, SA 5005, Australia
| | - Joshua S Harbort
- Center for Advanced Imaging, University of Queensland, Brisbane, QLD 4072, Australia
| | - Tom Coleman
- Department of Chemistry, University of Adelaide, Adelaide, SA 5005, Australia
| | - Jeanette E Stok
- School of Chemistry and Molecular Bioscience, University of Queensland, Brisbane, QLD 4072, Australia
| | - Jake A Yorke
- Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, U.K
| | - Luet-Lok Wong
- Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, U.K
| | - John B Bruning
- School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Paul V Bernhardt
- School of Chemistry and Molecular Bioscience, University of Queensland, Brisbane, QLD 4072, Australia
| | - James J De Voss
- School of Chemistry and Molecular Bioscience, University of Queensland, Brisbane, QLD 4072, Australia
| | - Jeffrey R Harmer
- Center for Advanced Imaging, University of Queensland, Brisbane, QLD 4072, Australia
| | - Stephen G Bell
- Department of Chemistry, University of Adelaide, Adelaide, SA 5005, Australia
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