1
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Sahil M, Singh T, Ghosh S, Mondal J. 3site Multisubstrate-Bound State of Cytochrome P450cam. J Am Chem Soc 2023; 145:23488-23502. [PMID: 37867463 DOI: 10.1021/jacs.3c06144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2023]
Abstract
We identified a multisubstrate-bound state, hereby referred as a 3site state, in cytochrome P450cam via integrating molecular dynamics simulation with nuclear magnetic resonance (NMR) pseudocontact shift measurements. The 3site state is a result of simultaneous binding of three camphor molecules in three locations around P450cam: (a) in a well-established "catalytic" site near heme, (b) in a kink-separated "waiting" site along channel-1, and (c) in a previously reported "allosteric" site at E, F, G, and H helical junctions. These three spatially distinct binding modes in the 3site state mutually communicate with each other via homotropic allostery and act cooperatively to render P450cam functional. The 3site state shows a significantly superior fit with NMR pseudo contact shift (PCS) data with a Q-score of 0.045 than previously known bound states and consists of D251 free of salt-bridges with K178 and R186, rendering the enzyme functionally primed. To date, none of the reported cocomplex of P450cam with its redox partner putidaredoxin (pdx) has been able to match solution NMR data and controversial pdx-induced opening of P450cam's channel-1 remains a matter of recurrent discourse. In this regard, inclusion of pdx to the 3site state is able to perfectly fit the NMR PCS measurement with a Q-score of 0.08 and disfavors the pdx-induced opening of channel-1, reconciling previously unexplained remarkably fast hydroxylation kinetics with a koff of 10.2 s-1. Together, our findings hint that previous experimental observations may have inadvertently captured the 3site state as an in vitro solution state, instead of the catalytic state alone, and provided a distinct departure from the conventional understanding of cytochrome P450.
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Affiliation(s)
- Mohammad Sahil
- Tata Institute of Fundamental Research, Hyderabad 500046, India
| | - Tejender Singh
- Tata Institute of Fundamental Research, Hyderabad 500046, India
| | - Soumya Ghosh
- Tata Institute of Fundamental Research, Hyderabad 500046, India
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2
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Miao Q, Nitsche C, Orton H, Overhand M, Otting G, Ubbink M. Paramagnetic Chemical Probes for Studying Biological Macromolecules. Chem Rev 2022; 122:9571-9642. [PMID: 35084831 PMCID: PMC9136935 DOI: 10.1021/acs.chemrev.1c00708] [Citation(s) in RCA: 35] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Indexed: 12/11/2022]
Abstract
Paramagnetic chemical probes have been used in electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) spectroscopy for more than four decades. Recent years witnessed a great increase in the variety of probes for the study of biological macromolecules (proteins, nucleic acids, and oligosaccharides). This Review aims to provide a comprehensive overview of the existing paramagnetic chemical probes, including chemical synthetic approaches, functional properties, and selected applications. Recent developments have seen, in particular, a rapid expansion of the range of lanthanoid probes with anisotropic magnetic susceptibilities for the generation of structural restraints based on residual dipolar couplings and pseudocontact shifts in solution and solid state NMR spectroscopy, mostly for protein studies. Also many new isotropic paramagnetic probes, suitable for NMR measurements of paramagnetic relaxation enhancements, as well as EPR spectroscopic studies (in particular double resonance techniques) have been developed and employed to investigate biological macromolecules. Notwithstanding the large number of reported probes, only few have found broad application and further development of probes for dedicated applications is foreseen.
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Affiliation(s)
- Qing Miao
- Leiden
Institute of Chemistry, Leiden University, Einsteinweg 55, Leiden 2333 CC, The Netherlands
- School
of Chemistry &Chemical Engineering, Shaanxi University of Science & Technology, Xi’an710021, China
| | - Christoph Nitsche
- Research
School of Chemistry, The Australian National
University, Sullivans Creek Road, Canberra, Australian Capital Territory 2601, Australia
| | - Henry Orton
- Research
School of Chemistry, The Australian National
University, Sullivans Creek Road, Canberra, Australian Capital Territory 2601, Australia
- ARC
Centre of Excellence for Innovations in Peptide & Protein Science,
Research School of Chemistry, Australian
National University, Sullivans Creek Road, Canberra, Australian Capital Territory 2601, Australia
| | - Mark Overhand
- Leiden
Institute of Chemistry, Leiden University, Einsteinweg 55, Leiden 2333 CC, The Netherlands
| | - Gottfried Otting
- Research
School of Chemistry, The Australian National
University, Sullivans Creek Road, Canberra, Australian Capital Territory 2601, Australia
- ARC
Centre of Excellence for Innovations in Peptide & Protein Science,
Research School of Chemistry, Australian
National University, Sullivans Creek Road, Canberra, Australian Capital Territory 2601, Australia
| | - Marcellus Ubbink
- Leiden
Institute of Chemistry, Leiden University, Einsteinweg 55, Leiden 2333 CC, The Netherlands
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3
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Poulos TL, Follmer AH. Updating the Paradigm: Redox Partner Binding and Conformational Dynamics in Cytochromes P450. Acc Chem Res 2022; 55:373-380. [PMID: 34965086 PMCID: PMC8959394 DOI: 10.1021/acs.accounts.1c00632] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
This Account summarizes recent findings centered on the role that redox partner binding, allostery, and conformational dynamics plays in cytochrome P450 proton coupled electron transfer. P450s are one of Nature's largest enzyme families and it is not uncommon to find a P450 wherever substrate oxidation is required in the formation of essential molecules critical to the life of the organism or in xenobiotic detoxification. P450s can operate on a remarkably large range of substrates from the very small to the very large, yet the overall P450 three-dimensional structure is conserved. Given this conservation of structure, it is generally assumed that the basic catalytic mechanism is conserved. In nearly all P450s, the O2 O-O bond must be cleaved heterolytically enabling one oxygen atom, the distal oxygen, to depart as water and leave behind a heme iron-linked O atom as the powerful oxidant that is used to activate the nearby substrate. For this process to proceed efficiently, externally supplied electrons and protons are required. Two protons must be added to the departing O atom while an electron is transferred from a redox partner that typically contains either a Fe2S2 or FMN redox center. The paradigm P450 used to unravel the details of these mechanisms has been the bacterial CYP101A1 or P450cam. P450cam is specific for its own Fe2S2 redox partner, putidaredoxin or Pdx, and it has long been postulated that Pdx plays an effector/allosteric role by possibly switching P450cam to an active conformation. Crystal structures, spectroscopic data, and direct binding experiments of the P450cam-Pdx complex provide some answers. Pdx shifts the conformation of P450cam to a more open state, a transition that is postulated to trigger the proton relay network required for O2 activation. An essential part of this proton relay network is a highly conserved Asp (sometimes Glu) that is known to be critical for activity in a number of P450s. How this Asp and proton delivery networks are connected to redox partner binding is quite simple. In the closed state, this Asp is tied down by salt bridges, but these salt bridges are ruptured when Pdx binds, leaving the Asp free to serve its role in proton transfer. An alternative hypothesis suggests that a specific proton relay network is not really necessary. In this scenario, the Asp plays a structural role in the open/close transition and merely opening the active site access channel is sufficient to enable solvent protons in for O2 protonation. Experiments designed to test these various hypotheses have revealed some surprises in both P450cam and other bacterial P450s. Molecular dynamics and crystallography show that P450cam can undergo rather significant conformational gymnastics that result in a large restructuring of the active site requiring multiple cis/trans proline isomerizations. It also has been found that X-ray driven substrate hydroxylation is a useful tool for better understanding the role that the essential Asp and surrounding residues play in catalysis. Here we summarize these recent results which provide a much more dynamic picture of P450 catalysis.
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Affiliation(s)
- Thomas L. Poulos
- Departments of Molecular Biology & Biochemistry, Pharmaceutical Sciences, and Chemistry, University of California, Irvine, Irvine, California 92697-3900, United States
| | - Alec H. Follmer
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
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4
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Skinner SP, Follmer AH, Ubbink M, Poulos TL, Houwing-Duistermaat JJ, Paci E. Partial Opening of Cytochrome P450cam (CYP101A1) Is Driven by Allostery and Putidaredoxin Binding. Biochemistry 2021; 60:2932-2942. [PMID: 34519197 DOI: 10.1021/acs.biochem.1c00406] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Cytochrome P450cam (CYP101A1) catalyzes the regio- and stereo-specific 5-exo-hydroxylation of camphor via a multistep catalytic cycle that involves two-electron transfer steps, with an absolute requirement that the second electron be donated by the ferrodoxin, putidaredoxin (Pdx). Whether P450cam, once camphor has bound to the active site and the substrate entry channel has closed, opens up upon Pdx binding, during the second electron transfer step, or it remains closed is still a matter of debate. A potential allosteric site for camphor binding has been identified and postulated to play a role in the binding of Pdx. Here, we have revisited paramagnetic NMR spectroscopy data and determined a heterogeneous ensemble of structures that explains the data, provides a complete representation of the P450cam/Pdx complex in solution, and reconciles alternative hypotheses. The allosteric camphor binding site is always present, and the conformational changes induced by camphor binding to this site facilitates Pdx binding. We also determined that the state to which Pdx binds comprises an ensemble of structures that have features of both the open and closed state. These results demonstrate that there is a finely balanced interaction between allosteric camphor binding and the binding of Pdx at high camphor concentrations.
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Affiliation(s)
- Simon P Skinner
- School of Molecular and Cell Biology and Astbury Centre, University of Leeds, Leeds LS2 9JT, U.K
| | - Alec H Follmer
- Department of Chemistry, University of California, Irvine, California 92697-3900, United States
| | - Marcellus Ubbink
- Leiden University, Institute of Chemistry, Einsteinweg 55, 2333 CC Leiden, The Netherlands
| | - Thomas L Poulos
- Department of Chemistry, University of California, Irvine, California 92697-3900, United States.,Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697-3900, United States.,Department of Pharmaceutical Sciences, University of California, Irvine, California 92697-3900, United States
| | | | - Emanuele Paci
- School of Molecular and Cell Biology and Astbury Centre, University of Leeds, Leeds LS2 9JT, U.K
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5
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Mammoser CC, Ramos S, Thielges MC. Active Site Hydrogen Bonding Induced in Cytochrome P450cam by Effector Putidaredoxin. Biochemistry 2021; 60:1699-1707. [PMID: 34006086 DOI: 10.1021/acs.biochem.1c00075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cytochrome P450s are diverse and powerful catalysts that can activate molecular oxygen to oxidize a wide variety of substrates. Catalysis relies on effective uptake of two electrons and two protons. For cytochrome P450cam, an archetypal member of the superfamily, the second electron must be supplied by the redox partner putidaredoxin (Pdx). Pdx also plays an effector role beyond electron transfer, but after decades the mechanism remains under investigation. We applied infrared spectroscopy to heme-ligated CN- to examine the influence of Pdx binding. The results indicate that Pdx induces the population of a conformation wherein the CN- ligand forms a strong hydrogen bond to a solvent water molecule, experimentally corroborating the formation of a proposed proton delivery network. Further, characterization of T252A P450cam implicates the side chain of Thr252 in regulating the population equilibrium of hydrogen-bonded states within the P450cam/Pdx complex, which could underlie its role in directing activated oxygen toward product formation and preventing reaction uncoupling through peroxide release.
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Affiliation(s)
- Claire C Mammoser
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Sashary Ramos
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Megan C Thielges
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
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6
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Dandekar BR, Ahalawat N, Mondal J. Reconciling conformational heterogeneity and substrate recognition in cytochrome P450. Biophys J 2021; 120:1732-1745. [PMID: 33675756 PMCID: PMC8204291 DOI: 10.1016/j.bpj.2021.02.040] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 02/20/2021] [Accepted: 02/24/2021] [Indexed: 01/08/2023] Open
Abstract
Cytochrome P450, the ubiquitous metalloenzyme involved in detoxification of foreign components, has remained one of the most popular systems for substrate-recognition process. However, despite being known for its high substrate specificity, the mechanistic basis of substrate-binding by archetypal system cytochrome P450cam has remained at odds with the contrasting reports of multiple diverse crystallographic structures of its substrate-free form. Here, we address this issue by elucidating the probability of mutual dynamical transition to the other crystallographic pose of cytochrome P450cam and vice versa via unbiased all-atom computer simulation. A robust Markov state model, constructed using adaptively sampled 84-μs-long molecular dynamics simulation trajectories, maps the broad and heterogenous P450cam conformational landscape into five key substates. In particular, the Markov state model identifies an intermediate-assisted dynamic equilibrium between a pair of conformations of P450cam, in which the substrate-recognition sites remain "closed" and "open," respectively. However, the estimate of a significantly higher stationary population of closed conformation, coupled with faster rate of open → closed transition than its reverse process, dictates that the net conformational equilibrium would be swayed in favor of "closed" conformation. Together, the investigation quantitatively infers that although a potential substrate of cytochrome P450cam would, in principle, explore a diverse array of conformations of substrate-free protein, it would mostly encounter a "closed" or solvent-occluded conformation and hence would follow an induced-fit-based recognition process. Overall, the work reconciles multiple precedent crystallographic, spectroscopic investigations and establishes how a statistical elucidation of conformational heterogeneity in protein would provide crucial insights in the mechanism of potential substrate-recognition process.
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Affiliation(s)
- Bhupendra R Dandekar
- Tata Institute of Fundamental Research, Center for Interdisciplinary Sciences, Hyderabad, India
| | - Navjeet Ahalawat
- Department of Molecular Biology, Biotechnology and Bioinformatics, Chaudhary Charan Singh Haryana Agricultural University, Hisar, India
| | - Jagannath Mondal
- Tata Institute of Fundamental Research, Center for Interdisciplinary Sciences, Hyderabad, India.
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7
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Guengerich FP, Child SA, Barckhausen IR, Goldfarb MH. Kinetic Evidence for an Induced Fit Mechanism in the Binding of the Substrate Camphor by Cytochrome P450 cam. ACS Catal 2021; 11:639-649. [PMID: 34327042 PMCID: PMC8318206 DOI: 10.1021/acscatal.0c04455] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Bacterial cytochrome P450 (P450) 101A1 (P450cam) has served as a prototype among the P450 enzymes and has high catalytic activity towards its cognate substrate, camphor. X-ray crystallography and NMR and IR spectroscopy have demonstrated the existence of multiple conformations of many P450s, including P450cam. Kinetic studies have indicated that substrate binding to several P450s is dominated by a conformational selection process, in which the substrate binds an individual conformer(s) of the unliganded enzyme. P450cam was found to differ in that binding of the substrate camphor is dominated by an induced fit mechanism, in which the enzyme binds camphor and then changes conformation, as evidenced by the equivalence of binding eigenvalues observed when varying both camphor and P450cam concentrations. The accessory protein putidaredoxin had no effect on substrate binding. Estimation of the rate of dissociation of the P450cam·camphor complex (15 s-1) and fitting of the data yield a minimal kinetic mechanism in which camphor binds (1.5 × 107 M-1 s-1) and the initial P450cam•camphor complex undergoes a reversible equilibrium (k forward 112 s-1, k reverse 28 s-1) to a final complex. This induced fit mechanism differs from those reported for several mammalian P450s and bacterial P450BM-3, indicative of the diversity of how P450s recognize multiple substrates. However, similar behavior was not observed with the alternate substrates (+)-α-pinene and 2-adamantanone, which probably utilize a conformational selection process.
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Affiliation(s)
- F Peter Guengerich
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, United States
| | - Stella A Child
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, United States
| | - Ian R Barckhausen
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, United States
| | - Margo H Goldfarb
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, United States
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8
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Denis M, Softley C, Giuntini S, Gentili M, Ravera E, Parigi G, Fragai M, Popowicz G, Sattler M, Luchinat C, Cerofolini L, Nativi C. The Photocatalyzed Thiol-ene reaction: A New Tag to Yield Fast, Selective and reversible Paramagnetic Tagging of Proteins. Chemphyschem 2020; 21:863-869. [PMID: 32092218 PMCID: PMC7384118 DOI: 10.1002/cphc.202000071] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 02/21/2020] [Indexed: 11/18/2022]
Abstract
Paramagnetic restraints have been used in biomolecular NMR for the last three decades to elucidate and refine biomolecular structures, but also to characterize protein-ligand interactions. A common technique to generate such restraints in proteins, which do not naturally contain a (paramagnetic) metal, consists in the attachment to the protein of a lanthanide-binding-tag (LBT). In order to design such LBTs, it is important to consider the efficiency and stability of the conjugation, the geometry of the complex (conformational exchanges and coordination) and the chemical inertness of the ligand. Here we describe a photo-catalyzed thiol-ene reaction for the cysteine-selective paramagnetic tagging of proteins. As a model, we designed an LBT with a vinyl-pyridine moiety which was used to attach our tag to the protein GB1 in fast and irreversible fashion. Our tag T1 yields magnetic susceptibility tensors of significant size with different lanthanides and has been characterized using NMR and relaxometry measurements.
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Affiliation(s)
- Maxime Denis
- Giotto Biotech, S.R.LVia Madonna del piano 650019Sesto Fiorentino (FI)Italy
- Department of Chemistry “Ugo Schiff”University of FlorenceVia della Lastruccia 350019Sesto Fiorentino (FI), Italy
| | - Charlotte Softley
- Biomolecular NMR, Department ChemieTechnical University of MunichLichtenbergstrasse 485747GarchingGermany
- Institute of Structural BiologyHelmholtz Center MunichNeuherbergGermany
| | - Stefano Giuntini
- Department of Chemistry “Ugo Schiff”University of FlorenceVia della Lastruccia 350019Sesto Fiorentino (FI), Italy
- Magnetic Resonance Center (CERM)University of Florence, and Consorzio Interuniversitario Risonanze Magnetiche di Metalloproteine (C.I.R.M.M.P)Via L. Sacconi 650019Sesto FIorentino (FI)Italy
| | - Matteo Gentili
- Giotto Biotech, S.R.LVia Madonna del piano 650019Sesto Fiorentino (FI)Italy
| | - Enrico Ravera
- Magnetic Resonance Center (CERM)University of Florence, and Consorzio Interuniversitario Risonanze Magnetiche di Metalloproteine (C.I.R.M.M.P)Via L. Sacconi 650019Sesto FIorentino (FI)Italy
| | - Giacomo Parigi
- Department of Chemistry “Ugo Schiff”University of FlorenceVia della Lastruccia 350019Sesto Fiorentino (FI), Italy
- Magnetic Resonance Center (CERM)University of Florence, and Consorzio Interuniversitario Risonanze Magnetiche di Metalloproteine (C.I.R.M.M.P)Via L. Sacconi 650019Sesto FIorentino (FI)Italy
| | - Marco Fragai
- Department of Chemistry “Ugo Schiff”University of FlorenceVia della Lastruccia 350019Sesto Fiorentino (FI), Italy
- Magnetic Resonance Center (CERM)University of Florence, and Consorzio Interuniversitario Risonanze Magnetiche di Metalloproteine (C.I.R.M.M.P)Via L. Sacconi 650019Sesto FIorentino (FI)Italy
| | - Grzegorz Popowicz
- Institute of Structural BiologyHelmholtz Center MunichNeuherbergGermany
| | - Michael Sattler
- Biomolecular NMR, Department ChemieTechnical University of MunichLichtenbergstrasse 485747GarchingGermany
- Institute of Structural BiologyHelmholtz Center MunichNeuherbergGermany
| | - Claudio Luchinat
- Department of Chemistry “Ugo Schiff”University of FlorenceVia della Lastruccia 350019Sesto Fiorentino (FI), Italy
- Magnetic Resonance Center (CERM)University of Florence, and Consorzio Interuniversitario Risonanze Magnetiche di Metalloproteine (C.I.R.M.M.P)Via L. Sacconi 650019Sesto FIorentino (FI)Italy
| | - Linda Cerofolini
- Magnetic Resonance Center (CERM)University of Florence, and Consorzio Interuniversitario Risonanze Magnetiche di Metalloproteine (C.I.R.M.M.P)Via L. Sacconi 650019Sesto FIorentino (FI)Italy
| | - Cristina Nativi
- Department of Chemistry “Ugo Schiff”University of FlorenceVia della Lastruccia 350019Sesto Fiorentino (FI), Italy
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9
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Ugur I, Chandrasekhar P. Proton relay network in P450cam formed upon docking of putidaredoxin. Proteins 2019; 88:558-572. [PMID: 31597203 DOI: 10.1002/prot.25835] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Revised: 09/13/2019] [Accepted: 09/28/2019] [Indexed: 11/08/2022]
Abstract
Cytochromes P450 are versatile heme-based enzymes responsible for vital life processes. Of these, P450cam (substrate camphor) has been most studied. Despite this, precise mechanisms of the key O─O cleavage step remain partly elusive to date; effects observed in various enzyme mutants remain partly unexplained. We have carried out extended (to 1000 ns) MM-MD and follow-on quantum mechanics/molecular mechanics computations, both on the well-studied FeOO state and on Cpd(0) (compound 0). Our simulations include (all camphor-bound): (a) WT (wild type), FeOO state. (b) WT, Cpd(0). (c) Pdx (Putidaredoxin, redox partner of P450)-docked-WT, FeOO state. (d) Pdx-docked WT, Cpd(0). (e) Pdx-docked T252A mutant, Cpd(0). Among our key findings: (a) Effect of Pdx docking appears to go far beyond that indicated in prior studies: it leads to specific alterations in secondary structure that create the crucial proton relay network. (b) Specific proton relay networks we identify are: FeOO(H)⋯T252⋯nH 2 O⋯D251 in WT; FeOO(H)⋯nH 2 O⋯D251 in T252A mutant; both occur with Pdx docking. (c) Direct interaction of D251 with -FeOOH is, respectively, rare/frequent in WT/T252A mutant. (d) In WT, T252 is in the proton relay network. (e) Positioning of camphor appears significant: when camphor is part of H-bonding network, second protonation appears to be facilitated.
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Affiliation(s)
- Ilke Ugur
- Research Division, Ashwin-Ushas Corporation, Marlboro, New Jersey
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10
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Chuo SW, Wang LP, Britt RD, Goodin DB. An Intermediate Conformational State of Cytochrome P450cam-CN in Complex with Putidaredoxin. Biochemistry 2019; 58:2353-2361. [PMID: 30994334 DOI: 10.1021/acs.biochem.9b00192] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Cytochrome P450cam is an archetypal example of the vast family of heme monooxygenases and serves as a model for an enzyme that is highly specific for both its substrate and reductase. During catalysis, it undergoes significant conformational changes of the F and G helices upon binding its substrate and redox partner, putidaredoxin (Pdx). Recent studies have shown that Pdx binding to the closed camphor-bound form of ferric P450cam results in its conversion to a fully open state. However, during catalytic turnover, it remains unclear whether this same conformational change also occurs or whether it is coupled to the formation of the critical compound I intermediate. Here, we have examined P450cam bound simultaneously by camphor, CN-, and Pdx as a mimic of the catalytically competent ferrous oxy-P450cam-Pdx state. The combined use of double electron-electron resonance and molecular dynamics showed direct observation of intermediate conformational states of the enzyme upon CN- and subsequent Pdx binding. This state is coupled to the movement of the I helix and residues at the active site, including Arg-186, Asp-251, and Thr-252. These movements enable occupation of a water molecule that has been implicated in proton delivery and peroxy bond cleavage to give compound I. These findings provide a detailed understanding of how the Pdx-induced conformational change may sequentially promote compound I formation followed by product release, while retaining stereoselective hydroxylation of the substrate of this highly specific monooxygenase.
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Affiliation(s)
- Shih-Wei Chuo
- Department of Chemistry , University of California, Davis , One Shields Avenue , Davis , California 95616 , United States
| | - Lee-Ping Wang
- Department of Chemistry , University of California, Davis , One Shields Avenue , Davis , California 95616 , United States
| | - R David Britt
- Department of Chemistry , University of California, Davis , One Shields Avenue , Davis , California 95616 , United States
| | - David B Goodin
- Department of Chemistry , University of California, Davis , One Shields Avenue , Davis , California 95616 , United States
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11
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Ahalawat N, Mondal J. Mapping the Substrate Recognition Pathway in Cytochrome P450. J Am Chem Soc 2018; 140:17743-17752. [PMID: 30479124 DOI: 10.1021/jacs.8b10840] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Cytochrome P450s are ubiquitous metalloenzymes involved in the metabolism and detoxification of foreign components via catalysis of the hydroxylation reactions of a vast array of organic substrates. However, the mechanism underlying the pharmaceutically critical process of substrate access to the catalytic center of cytochrome P450 is a long-standing puzzle, further complicated by the crystallographic evidence of a closed catalytic center in both substrate-free and substrate-bound cytochrome P450. Here, we address a crucial question whether the conformational heterogeneity prevalent in cytochrome P450 translates to heterogeneous pathways for substrate access to the catalytic center of these metalloenzymes. By atomistically capturing the full process of spontaneous substrate association from bulk solvent to the occluded catalytic center of an archetypal system P450cam in multi-microsecond-long continuous unbiased molecular dynamics simulations, we here demonstrate that the substrate recognition in P450cam always occurs through a single well-defined dominant pathway. The simulated final bound pose resulting from these unguided simulations is in striking resemblance with the crystallographic bound pose. Each individual binding trajectory reveals that the substrate, initially placed at random locations in bulk solvent, spontaneously lands on a single key channel on the protein-surface of P450cam and resides there for an uncharacteristically long period, before correctly identifying the occluded target-binding cavity. Surprisingly, the passage of substrate to the closed catalytic center is not accompanied by any large-scale opening in protein. Rather, the unbiased simulated trajectories (∼57 μs) and underlying Markov state model, in combination with free-energy analysis, unequivocally show that the substrate recognition process in P450cam needs a substrate-induced side-chain displacement coupled with a complex array of dynamical interconversions of multiple metastable substrate conformations. Further, the work reconciles multiple precedent experimental and theoretical observations on P450cam and establishes a comprehensive view of substrate-recognition in cytochrome P450 that only occurs via substrate-induced structural rearrangements.
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Affiliation(s)
- Navjeet Ahalawat
- Tata Institute of Fundamental Research, Center for Interdisciplinary Sciences , Hyderabad 500107 , India
| | - Jagannath Mondal
- Tata Institute of Fundamental Research, Center for Interdisciplinary Sciences , Hyderabad 500107 , India
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12
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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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13
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Ramos S, Basom EJ, Thielges MC. Conformational Change Induced by Putidaredoxin Binding to Ferrous CO-ligated Cytochrome P450cam Characterized by 2D IR Spectroscopy. Front Mol Biosci 2018; 5:94. [PMID: 30483514 PMCID: PMC6243089 DOI: 10.3389/fmolb.2018.00094] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 10/22/2018] [Indexed: 11/16/2022] Open
Abstract
The importance of conformational dynamics to protein function is now well-appreciated. An outstanding question is whether they are involved in the effector role played by putidaredoxin (Pdx) in its reduction of the O2 complex of cytochrome P450cam (P450cam), an archetypical member of the cytochrome P450 superfamily. Recent studies have reported that binding of Pdx induces a conformational change from a closed to an open state of ferric P450cam, but a similar conformational change does not appear to occur for the ferrous, CO-ligated enzyme. To better understand the effector role of Pdx when binding the ferrous, CO-ligated P450cam, we applied 2D IR spectroscopy to compare the conformations and dynamics of the wild-type (wt) enzyme in the absence and presence of Pdx, as well as of L358P P450cam (L358P), which has served as a putative model for the Pdx complex. The CO vibrations of the Pdx complex and L358P report population of two conformational states in which the CO experiences distinct environments. The dynamics among the CO frequencies indicate that the energy landscape of substates within one conformation are reflective of the closed state of P450cam, and for the other conformation, differ from the free wt enzyme, but are equivalent between the Pdx complex and L358P. The two states co-populated by the Pdx complex are postulated to reflect a loosely bound encounter complex and a more tightly bound state, as is commonly observed for the dynamic complexes of redox partners. Significantly, this study shows that the binding of Pdx to ferrous, CO-ligated P450cam does perturb the conformational ensemble in a way that might underlie the effector role of Pdx.
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Affiliation(s)
- Sashary Ramos
- Department of Chemistry, Indiana University, Bloomington, IN, United States
| | - Edward J Basom
- Department of Chemistry, Indiana University, Bloomington, IN, United States
| | - Megan C Thielges
- Department of Chemistry, Indiana University, Bloomington, IN, United States
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14
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Goodin DB, Chuo SW, Liou SH. Conformational Changes in Cytochrome P450cam and the Effector Role of Putidaredoxin. DIOXYGEN-DEPENDENT HEME ENZYMES 2018. [DOI: 10.1039/9781788012911-00292] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The cytochromes P450 form an enormous family of over 20 000 enzyme variants found in all branches of life. They catalyze the O2 dependent monooxygenation of a wide range of substrates in reactions important to drug metabolism, biosynthesis and energy utilization. Understanding how they function is important for biomedical science and requires a full description of their notorious propensity for specificity and promiscuity. The bacterial P450cam is an unusual example, having the most well characterized chemical mechanism of all of the forms. It also undergoes an increasingly well characterized structural change upon substrate binding, which may be similar to to that displayed by some, but not all forms of P450. Finally, P450cam is one of the rare forms that have a strict requirement for a particular electron donor, putidaredoxin (pdx). Pdx provides the required electrons for enzyme turnover, but it also induces specific changes in the enzyme to allow enzyme turnover, long known as its effector role. This review summarizes recent crystallographic and double electron–electron resonance studies that have revealed the effects of substrate and pdx binding on the structure of P450cam. We describe an emerging idea for how pdx exerts its effector function by inducing a conformational change in the enzyme. This change then propagates to the active site to enable cleavage of the ferric–hydroperoxy bond during catalysis, and appears to provide a very elegant approach for P450cam to attain both high efficiency and protection from oxidative damage.
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Affiliation(s)
- David B. Goodin
- University of California Davis, Department of Chemistry One Shields Ave Davis CA 95616 USA
| | - Shih-Wei Chuo
- University of California Davis, Department of Chemistry One Shields Ave Davis CA 95616 USA
| | - Shu-Hao Liou
- Research Group EPR Spectroscopy, Max-Planck-Institute for Biophysical Chemistry Göttingen 37077 Germany
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15
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Sugiki T, Furuita K, Fujiwara T, Kojima C. Amino Acid Selective 13C Labeling and 13C Scrambling Profile Analysis of Protein α and Side-Chain Carbons in Escherichia coli Utilized for Protein Nuclear Magnetic Resonance. Biochemistry 2018; 57:3576-3589. [PMID: 29924600 DOI: 10.1021/acs.biochem.8b00182] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Amino acid selective isotope labeling is an important nuclear magnetic resonance technique, especially for larger proteins, providing strong bases for the unambiguous resonance assignments and information concerning the structure, dynamics, and intermolecular interactions. Amino acid selective 15N labeling suffers from isotope dilution caused by metabolic interconversion of the amino acids, resulting in isotope scrambling within the target protein. Carbonyl 13C atoms experience less isotope scrambling than the main-chain 15N atoms do. However, little is known about the side-chain 13C atoms. Here, the 13C scrambling profiles of the Cα and side-chain carbons were investigated for 15N scrambling-prone amino acids, such as Leu, Ile, Tyr, Phe, Thr, Val, and Ala. The level of isotope scrambling was substantially lower in 13Cα and 13C side-chain labeling than in 15N labeling. We utilized this reduced scrambling-prone character of 13C as a simple and efficient method for amino acid selective 13C labeling using an Escherichia coli cold-shock expression system and high-cell density fermentation. Using this method, the 13C labeling efficiency was >80% for Leu and Ile, ∼60% for Tyr and Phe, ∼50% for Thr, ∼40% for Val, and 30-40% for Ala. 1H-15N heteronuclear single-quantum coherence signals of the 15N scrambling-prone amino acid were also easily filtered using 15N-{13Cα} spin-echo difference experiments. Our method could be applied to the assignment of the 55 kDa protein.
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Affiliation(s)
- Toshihiko Sugiki
- Institute for Protein Research , Osaka University , 3-2 Yamadaoka , Suita , Osaka 565-0871 , Japan
| | - Kyoko Furuita
- Institute for Protein Research , Osaka University , 3-2 Yamadaoka , Suita , Osaka 565-0871 , Japan
| | - Toshimichi Fujiwara
- Institute for Protein Research , Osaka University , 3-2 Yamadaoka , Suita , Osaka 565-0871 , Japan
| | - Chojiro Kojima
- Institute for Protein Research , Osaka University , 3-2 Yamadaoka , Suita , Osaka 565-0871 , Japan.,Graduate School of Engineering Science , Yokohama National University , 79-5 Tokiwadai , Hodogaya-ku, Yokohama 240-8501 , Japan
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16
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Structure of cytochrome P450 2B4 with an acetate ligand and an active site hydrogen bond network similar to oxyferrous P450cam. J Inorg Biochem 2018; 185:17-25. [PMID: 29730233 DOI: 10.1016/j.jinorgbio.2018.04.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 04/19/2018] [Accepted: 04/21/2018] [Indexed: 02/03/2023]
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17
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Gao J, Liang E, Ma R, Li F, Liu Y, Liu J, Jiang L, Li C, Dai H, Wu J, Su X, He W, Ruan K. Fluorine Pseudocontact Shifts Used for Characterizing the Protein-Ligand Interaction Mode in the Limit of NMR Intermediate Exchange. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201707114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Jia Gao
- Hefei National Laboratory for Physical Science at the Microscale; School of Life Science; University of Science and Technology of China; Huangshan Road Hefei Anhui 230027 P. R. China
- Center of Medical Physics and Technology; Hefei Institute of Physical Science, Cancer Hospital; Chinese Academy of Science; Hefei Anhui 230031 P. R. China
| | - E Liang
- Department of pharmacology and Pharmaceutical Sciences; School of Medicine, Tsinghua-Peking Joint centers for Lifer Sciences; Tsinghua University; Beijing 100084 P. R. China
| | - Rongsheng Ma
- Hefei National Laboratory for Physical Science at the Microscale; School of Life Science; University of Science and Technology of China; Huangshan Road Hefei Anhui 230027 P. R. China
| | - Fudong Li
- Hefei National Laboratory for Physical Science at the Microscale; School of Life Science; University of Science and Technology of China; Huangshan Road Hefei Anhui 230027 P. R. China
| | - Yixiang Liu
- Key Laboratory of Magnet Resonance in Biological Systems; State Key Laboratory of Magnet Resonance and Atomic and Molecular Physics; Wuhan Center for Magnet Resonance Department; Wuhan Institute of Physics and Mathematics; Chinese Academy of Science; Wuhan Hubei 430071 P. R. China
| | - Jiuyang Liu
- Hefei National Laboratory for Physical Science at the Microscale; School of Life Science; University of Science and Technology of China; Huangshan Road Hefei Anhui 230027 P. R. China
| | - Ling Jiang
- Key Laboratory of Magnet Resonance in Biological Systems; State Key Laboratory of Magnet Resonance and Atomic and Molecular Physics; Wuhan Center for Magnet Resonance Department; Wuhan Institute of Physics and Mathematics; Chinese Academy of Science; Wuhan Hubei 430071 P. R. China
| | - Conggang Li
- Key Laboratory of Magnet Resonance in Biological Systems; State Key Laboratory of Magnet Resonance and Atomic and Molecular Physics; Wuhan Center for Magnet Resonance Department; Wuhan Institute of Physics and Mathematics; Chinese Academy of Science; Wuhan Hubei 430071 P. R. China
| | - Haiming Dai
- Center of Medical Physics and Technology; Hefei Institute of Physical Science, Cancer Hospital; Chinese Academy of Science; Hefei Anhui 230031 P. R. China
| | - Jihui Wu
- Hefei National Laboratory for Physical Science at the Microscale; School of Life Science; University of Science and Technology of China; Huangshan Road Hefei Anhui 230027 P. R. China
| | - Xuncheng Su
- State Key Laboratory of Elemento-Organic Chemistry; Collatorative Innovation Center of Chemical Science and Engineering(Tianjin); Nankai University; Tianjin 300071 P. R. China
| | - Wei He
- Department of pharmacology and Pharmaceutical Sciences; School of Medicine, Tsinghua-Peking Joint centers for Lifer Sciences; Tsinghua University; Beijing 100084 P. R. China
| | - Ke Ruan
- Hefei National Laboratory for Physical Science at the Microscale; School of Life Science; University of Science and Technology of China; Huangshan Road Hefei Anhui 230027 P. R. China
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18
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Gao J, Liang E, Ma R, Li F, Liu Y, Liu J, Jiang L, Li C, Dai H, Wu J, Su X, He W, Ruan K. Fluorine Pseudocontact Shifts Used for Characterizing the Protein-Ligand Interaction Mode in the Limit of NMR Intermediate Exchange. Angew Chem Int Ed Engl 2017; 56:12982-12986. [DOI: 10.1002/anie.201707114] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 08/15/2017] [Indexed: 11/10/2022]
Affiliation(s)
- Jia Gao
- Hefei National Laboratory for Physical Science at the Microscale; School of Life Science; University of Science and Technology of China; Huangshan Road Hefei Anhui 230027 P. R. China
- Center of Medical Physics and Technology; Hefei Institute of Physical Science, Cancer Hospital; Chinese Academy of Science; Hefei Anhui 230031 P. R. China
| | - E Liang
- Department of pharmacology and Pharmaceutical Sciences; School of Medicine, Tsinghua-Peking Joint centers for Lifer Sciences; Tsinghua University; Beijing 100084 P. R. China
| | - Rongsheng Ma
- Hefei National Laboratory for Physical Science at the Microscale; School of Life Science; University of Science and Technology of China; Huangshan Road Hefei Anhui 230027 P. R. China
| | - Fudong Li
- Hefei National Laboratory for Physical Science at the Microscale; School of Life Science; University of Science and Technology of China; Huangshan Road Hefei Anhui 230027 P. R. China
| | - Yixiang Liu
- Key Laboratory of Magnet Resonance in Biological Systems; State Key Laboratory of Magnet Resonance and Atomic and Molecular Physics; Wuhan Center for Magnet Resonance Department; Wuhan Institute of Physics and Mathematics; Chinese Academy of Science; Wuhan Hubei 430071 P. R. China
| | - Jiuyang Liu
- Hefei National Laboratory for Physical Science at the Microscale; School of Life Science; University of Science and Technology of China; Huangshan Road Hefei Anhui 230027 P. R. China
| | - Ling Jiang
- Key Laboratory of Magnet Resonance in Biological Systems; State Key Laboratory of Magnet Resonance and Atomic and Molecular Physics; Wuhan Center for Magnet Resonance Department; Wuhan Institute of Physics and Mathematics; Chinese Academy of Science; Wuhan Hubei 430071 P. R. China
| | - Conggang Li
- Key Laboratory of Magnet Resonance in Biological Systems; State Key Laboratory of Magnet Resonance and Atomic and Molecular Physics; Wuhan Center for Magnet Resonance Department; Wuhan Institute of Physics and Mathematics; Chinese Academy of Science; Wuhan Hubei 430071 P. R. China
| | - Haiming Dai
- Center of Medical Physics and Technology; Hefei Institute of Physical Science, Cancer Hospital; Chinese Academy of Science; Hefei Anhui 230031 P. R. China
| | - Jihui Wu
- Hefei National Laboratory for Physical Science at the Microscale; School of Life Science; University of Science and Technology of China; Huangshan Road Hefei Anhui 230027 P. R. China
| | - Xuncheng Su
- State Key Laboratory of Elemento-Organic Chemistry; Collatorative Innovation Center of Chemical Science and Engineering(Tianjin); Nankai University; Tianjin 300071 P. R. China
| | - Wei He
- Department of pharmacology and Pharmaceutical Sciences; School of Medicine, Tsinghua-Peking Joint centers for Lifer Sciences; Tsinghua University; Beijing 100084 P. R. China
| | - Ke Ruan
- Hefei National Laboratory for Physical Science at the Microscale; School of Life Science; University of Science and Technology of China; Huangshan Road Hefei Anhui 230027 P. R. China
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19
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Thermodynamics of camphor migration in cytochrome P450cam by atomistic simulations. Sci Rep 2017; 7:7736. [PMID: 28798338 PMCID: PMC5552751 DOI: 10.1038/s41598-017-07993-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 07/05/2017] [Indexed: 01/12/2023] Open
Abstract
Understanding the mechanisms of ligand binding to enzymes is of paramount importance for the design of new drugs. Here, we report on the use of a novel biased molecular dynamics (MD) methodology to study the mechanism of camphor binding to cytochrome P450cam. Microsecond-long MD simulations allowed us to observe reaction coordinates characterizing ligand diffusion from the active site of cytochrome P450cam to solvent via three egress routes. These atomistic simulations were used to estimate thermodynamic quantities along the reaction coordinates and indicate diverse binding configurations. The results suggest that the diffusion of camphor along the pathway near the substrate recognition site (SRS) is thermodynamically preferred. In addition, we show that the diffusion near the SRS is triggered by a transition from a heterogeneous collection of closed ligand-bound conformers to the basin comprising the open conformations of cytochrome P450cam. The conformational change accompanying this switch is characterized by the retraction of the F and G helices and the disorder of the B' helix. These results are corroborated by experimental studies and provide detailed insight into ligand binding and conformational behavior of the cytochrome family. The presented methodology is general and can be applied to other ligand-protein systems.
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20
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Liou SH, Myers WK, Oswald JD, Britt RD, Goodin DB. Putidaredoxin Binds to the Same Site on Cytochrome P450cam in the Open and Closed Conformation. Biochemistry 2017; 56:4371-4378. [DOI: 10.1021/acs.biochem.7b00564] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Shu-Hao Liou
- Department
of Chemistry, University of California, Davis, California 95616, United States
- Research
Group EPR Spectroscopy, Max-Planck-Institute for Biophysical Chemistry, Göttingen 37077, Germany
| | - William K. Myers
- Centre
for Advanced Electron Spin Resonance, Inorganic Chemistry Laboratory, University of Oxford, Oxford OX1 3QR, United Kingdom
| | - Jason D. Oswald
- Department
of Chemistry, University of California, Davis, California 95616, United States
| | - R. David Britt
- Department
of Chemistry, University of California, Davis, California 95616, United States
| | - David B. Goodin
- Department
of Chemistry, University of California, Davis, California 95616, United States
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21
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Pearce BJG, Jabar S, Loh CT, Szabo M, Graham B, Otting G. Structure restraints from heteronuclear pseudocontact shifts generated by lanthanide tags at two different sites. JOURNAL OF BIOMOLECULAR NMR 2017; 68:19-32. [PMID: 28434103 DOI: 10.1007/s10858-017-0111-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 04/11/2017] [Indexed: 05/14/2023]
Abstract
Pseudocontact shifts (PCS) encode long-range information on 3D structures of protein backbones and side-chains. The level of structural detail that can be obtained increases with the number of different sites tagged with a paramagnetic metal ion to generate PCSs. Here we show that PCSs from two different sites can suffice to determine the structure of polypeptide chains and their location and orientation relative to the magnetic susceptibility tensor χ, provided that PCSs are available for 1H as well as heteronuclear spins. In addition, PCSs from two different sites are shown to provide detailed structural information on the conformation of methyl group-bearing amino-acid side-chains. A previously published ensemble structure of ubiquitin is shown to explain the magnetic susceptibility and alignment tensors slightly better than structures that try to explain the experimental data by a single conformation, illustrating the potential of PCSs as a tool to investigate small conformational changes.
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Affiliation(s)
- Benjamin J G Pearce
- Research School of Chemistry, Australian National University, Canberra, ACT, 2601, Australia
| | - Shereen Jabar
- Research School of Chemistry, Australian National University, Canberra, ACT, 2601, Australia
| | - Choy-Theng Loh
- Research School of Chemistry, Australian National University, Canberra, ACT, 2601, Australia
| | - Monika Szabo
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Bim Graham
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Gottfried Otting
- Research School of Chemistry, Australian National University, Canberra, ACT, 2601, Australia.
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22
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Identification of productive and futile encounters in an electron transfer protein complex. Proc Natl Acad Sci U S A 2017; 114:E1840-E1847. [PMID: 28223532 DOI: 10.1073/pnas.1616813114] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Well-defined, stereospecific states in protein complexes are often in exchange with an ensemble of more dynamic orientations: the encounter states. The structure of the stereospecific complex between cytochrome P450cam and putidaredoxin was solved recently by X-ray diffraction as well as paramagnetic NMR spectroscopy. Other than the stereospecific complex, the NMR data clearly show the presence of additional states in the complex in solution. In these encounter states, populated for a small percentage of the time, putidaredoxin assumes multiple orientations and samples a large part of the surface of cytochrome P450cam. To characterize the nature of the encounter states, an extensive paramagnetic NMR dataset has been analyzed using the Maximum Occurrence of Regions methodology. The analysis reveals the location and maximal spatial extent of the additional states needed to fully explain the NMR data. Under the assumption of sparsity of the size of the conformational ensemble, several minor states can be located quite precisely. The distribution of these minor states correlates with the electrostatic potential map around cytochrome P450cam. Whereas some minor states are on isolated positively charged patches, others are connected to the stereospecific site via positively charged paths. The existence of electrostatically favorable pathways between the stereospecific interaction site and the different minor states or lack thereof suggests a means to discriminate between productive and futile encounter states.
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23
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Nitsche C, Otting G. Pseudocontact shifts in biomolecular NMR using paramagnetic metal tags. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2017; 98-99:20-49. [PMID: 28283085 DOI: 10.1016/j.pnmrs.2016.11.001] [Citation(s) in RCA: 114] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 11/11/2016] [Accepted: 11/12/2016] [Indexed: 05/14/2023]
Affiliation(s)
- Christoph Nitsche
- Australian National University, Research School of Chemistry, Canberra, ACT 2601, Australia.
| | - Gottfried Otting
- Australian National University, Research School of Chemistry, Canberra, ACT 2601, Australia. http://www.rsc.anu.edu.au/~go/index.html
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24
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Liou SH, Mahomed M, Lee YT, Goodin DB. Effector Roles of Putidaredoxin on Cytochrome P450cam Conformational States. J Am Chem Soc 2016; 138:10163-72. [PMID: 27452076 DOI: 10.1021/jacs.6b04110] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In this study, the effector role of Pdx (putidaredoxin) on cytochrome P450cam conformation is refined by attaching two different spin labels, MTSL or BSL (bifunctional spin-label) onto the F or G helices and using DEER (double electron-electron resonance) to measure the distance between labels. Recent EPR and crystallographic studies have observed that oxidized Pdx induces substrate-bound P450cam to change from the closed to the open state. However, this change was not observed by DEER in the reduced Pdx complex with carbon-monoxide-bound P450cam (Fe(2+)CO). In addition, recent NMR studies have failed to observe a change in P450cam conformation upon binding Pdx. Hence, resolving these issues is important for a full understanding the effector role of Pdx. Here we show that oxidized Pdx induces camphor-bound P450cam to shift from the closed to the open conformation when labeled on either the F or G helices with MTSL. BSL at these sites can either narrow the distance distribution widths dramatically or alter the extent of the conformational change. In addition, we report DEER spectra on a mixed oxidation state containing oxidized Pdx and ferrous CO-bound P450cam, showing that P450cam remains closed. This indicates that CO binding to the heme prevents P450cam from opening, overriding the influence exerted by Pdx binding. Finally, we report the open form P450cam crystal structure with substrate bound, which suggests that crystal packing effects may prevent conformational conversion. Using multiple labeling approaches, DEER provides a unique perspective to resolve how the conformation of P450cam depends on Pdx and ligand states.
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Affiliation(s)
- Shu-Hao Liou
- Department of Chemistry, University of California, Davis , One Shields Avenue, Davis, California 95616, United States
| | - Mavish Mahomed
- Department of Chemistry, University of California, Davis , One Shields Avenue, Davis, California 95616, United States
| | - Young-Tae Lee
- Department of Chemistry, University of California, Davis , One Shields Avenue, Davis, California 95616, United States
| | - David B Goodin
- Department of Chemistry, University of California, Davis , One Shields Avenue, Davis, California 95616, United States
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25
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Abstract
The heme iron of cytochromes P450 must be reduced to bind and activate molecular oxygen for substrate oxidation. Reducing equivalents are derived from a redox partner, which requires the formation of a protein-protein complex. A subject of increasing discussion is the role that redox partner binding plays, if any, in favoring significant structural changes in the P450s that are required for activity. Many P450s now have been shown to experience large open and closed motions. Several structural and spectral studies indicate that the well-studied P450cam adopts the open conformation when its redox partner, putidaredoxin (Pdx), binds, whereas recent NMR studies indicate that this view is incorrect. Given the relevance of this discrepancy to P450 chemistry, it is important to determine whether Pdx favors the open or closed form of P450cam. Here, we have used both computational and experimental isothermal titration calorimetry studies that unequivocally show Pdx favors binding to the open form of P450cam. Analyses of molecular-dynamic trajectories also provide insights into intermediate conformational states that could be relevant to catalysis.
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26
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Basom EJ, Maj M, Cho M, Thielges MC. Site-Specific Characterization of Cytochrome P450cam Conformations by Infrared Spectroscopy. Anal Chem 2016; 88:6598-606. [PMID: 27185328 DOI: 10.1021/acs.analchem.6b01520] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Conformational changes are central to protein function but challenging to characterize with both high spatial and temporal precision. The inherently fast time scale and small chromophores of infrared (IR) spectroscopy are well-suited for characterization of potentially rapidly fluctuating environments, and when frequency-resolved probes are incorporated to overcome spectral congestion, enable characterization of specific sites in proteins. We selectively incorporated p-cyanophenylalanine (CNF) as a vibrational probe at five distinct locations in the enzyme cytochrome P450cam and used IR spectroscopy to characterize the environments in substrate and/or ligand complexes reflecting those in the catalytic cycle. Molecular dynamics (MD) simulations were performed to provide a structural basis for spectral interpretation. Together the experimental and simulation data suggest that the CN frequencies are sensitive to both long-range influences, resulting from the particular location of a residue within the enzyme, as well as short-range influences from hydrogen bonding and packing interactions. The IR spectra demonstrate that the environments and effects of substrate and/or ligand binding are different at each position probed and also provide evidence that a single site can experience multiple environments. This study illustrates how IR spectroscopy, when combined with the spectral decongestion and spatial selectivity afforded by CNF incorporation, provides detailed information about protein structural changes that underlie function.
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Affiliation(s)
- Edward J Basom
- Department of Chemistry, Indiana University , 800 East Kirkwood, Bloomington, Indiana 47405, United States
| | - Michał Maj
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Korea University , Seoul 02841, Republic of Korea.,Department of Chemistry, Korea University , Seoul 02841, Republic of Korea
| | - Minhaeng Cho
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Korea University , Seoul 02841, Republic of Korea.,Department of Chemistry, Korea University , Seoul 02841, Republic of Korea
| | - Megan C Thielges
- Department of Chemistry, Indiana University , 800 East Kirkwood, Bloomington, Indiana 47405, United States
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27
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Álvarez L, Lewis-Ballester A, Roitberg A, Estrin DA, Yeh SR, Marti MA, Capece L. Structural Study of a Flexible Active Site Loop in Human Indoleamine 2,3-Dioxygenase and Its Functional Implications. Biochemistry 2016; 55:2785-93. [PMID: 27112409 DOI: 10.1021/acs.biochem.6b00077] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Human indoleamine 2,3-dioxygenase catalyzes the oxidative cleavage of tryptophan to N-formyl kynurenine, the initial and rate-limiting step in the kynurenine pathway. Additionally, this enzyme has been identified as a possible target for cancer therapy. A 20-amino acid protein segment (the JK loop), which connects the J and K helices, was not resolved in the reported hIDO crystal structure. Previous studies have shown that this loop undergoes structural rearrangement upon substrate binding. In this work, we apply a combination of replica exchange molecular dynamics simulations and site-directed mutagenesis experiments to characterize the structure and dynamics of this protein region. Our simulations show that the JK loop can be divided into two regions: the first region (JK loop(C)) displays specific and well-defined conformations and is within hydrogen bonding distance of the substrate, while the second region (JK loop(N)) is highly disordered and exposed to the solvent. The peculiar flexible nature of JK loop(N) suggests that it may function as a target for post-translational modifications and/or a mediator for protein-protein interactions. In contrast, hydrogen bonding interactions are observed between the substrate and Thr379 in the highly conserved "GTGG" motif of JK loop(C), thereby anchoring JK loop(C) in a closed conformation, which secures the appropriate substrate binding mode for catalysis. Site-directed mutagenesis experiments confirm the key role of this residue, highlighting the importance of the JK loop(C) conformation in regulating the enzymatic activity. Furthermore, the existence of the partially and totally open conformations in the substrate-free form suggests a role of JK loop(C) in controlling substrate and product dynamics.
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Affiliation(s)
- Lucía Álvarez
- Dto. de Química Inorgánica, Analítica y Química Física, Fac. de Ciencias Exactas y Naturales, Universidad de Buenos Aires , Buenos Aires C1428EGA, Argentina.,INQUIMAE-CONICET , Buenos Aires C1428EGA, Argentina
| | - Ariel Lewis-Ballester
- Department of Physiology and Biophysics, Albert Einstein College of Medicine , 1300 Morris Park Avenue, New York, New York 10461, United States
| | - Adrián Roitberg
- Department of Chemistry, University of Florida , 440 Leigh Hall, Gainesville, Florida 32611-7200, United States
| | - Darío A Estrin
- Dto. de Química Inorgánica, Analítica y Química Física, Fac. de Ciencias Exactas y Naturales, Universidad de Buenos Aires , Buenos Aires C1428EGA, Argentina.,INQUIMAE-CONICET , Buenos Aires C1428EGA, Argentina
| | - Syun-Ru Yeh
- Department of Physiology and Biophysics, Albert Einstein College of Medicine , 1300 Morris Park Avenue, New York, New York 10461, United States
| | - Marcelo A Marti
- Dto. de Química Biologica Fac. de Ciencias Exactas y Naturales, Universidad de Buenos Aires , Buenos Aires C1428EGA, Argentina.,IQUIBICEN-CONICET , Buenos Aires C1428EGA, Argentina
| | - Luciana Capece
- Dto. de Química Inorgánica, Analítica y Química Física, Fac. de Ciencias Exactas y Naturales, Universidad de Buenos Aires , Buenos Aires C1428EGA, Argentina.,INQUIMAE-CONICET , Buenos Aires C1428EGA, Argentina
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28
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Colthart AM, Tietz DR, Ni Y, Friedman JL, Dang M, Pochapsky TC. Detection of substrate-dependent conformational changes in the P450 fold by nuclear magnetic resonance. Sci Rep 2016; 6:22035. [PMID: 26911901 PMCID: PMC4766564 DOI: 10.1038/srep22035] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Accepted: 02/03/2016] [Indexed: 01/23/2023] Open
Abstract
Cytochrome P450 monooxygenases typically catalyze the insertion of one atom of oxygen from O2 into unactivated carbon-hydrogen and carbon-carbon bonds, with concomitant reduction of the other oxygen atom to H2O by NAD(P)H. Comparison of the average structures of the camphor hydroxylase cytochrome P450(cam) (CYP101) obtained from residual dipolar coupling (RDC)-restrained molecular dynamics (MD) in the presence and absence of substrate camphor shows structural displacements resulting from the essential collapse of the active site upon substrate removal. This collapse has conformational consequences that extend across the protein structure, none of which were observed in analogous crystallographic structures. Mutations were made to test the involvement of the observed conformational changes in substrate binding and recognition. All of the mutations performed based upon the NMR-detected perturbations, even those remote from the active site, resulted in modified substrate selectivity, enzyme efficiency and/or haem iron spin state. The results demonstrate that solution NMR can provide insights into enzyme structure-function relationships that are difficult to obtain by other methods.
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Affiliation(s)
- Allison M. Colthart
- Departments of Chemistry and Biochemistry Brandeis University, 415 South St., Waltham MA 02454-9110, USA
| | - Drew R. Tietz
- Departments of Chemistry and Biochemistry Brandeis University, 415 South St., Waltham MA 02454-9110, USA
| | - Yuhua Ni
- Departments of Chemistry and Biochemistry Brandeis University, 415 South St., Waltham MA 02454-9110, USA
| | - Jessica L. Friedman
- Departments of Chemistry and Biochemistry Brandeis University, 415 South St., Waltham MA 02454-9110, USA
| | - Marina Dang
- Departments of Chemistry and Biochemistry Brandeis University, 415 South St., Waltham MA 02454-9110, USA
| | - Thomas C. Pochapsky
- Departments of Chemistry and Biochemistry Brandeis University, 415 South St., Waltham MA 02454-9110, USA
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29
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Ma RS, Li QF, Wang AD, Zhang JH, Liu ZJ, Wu JH, Su XC, Ruan K. Determination of pseudocontact shifts of low-populated excited states by NMR chemical exchange saturation transfer. Phys Chem Chem Phys 2016; 18:13794-8. [DOI: 10.1039/c6cp01127f] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Angular and distance restraints for low populated excited conformations are studied using PCS–CEST NMR spectroscopy.
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Affiliation(s)
- R. S. Ma
- Hefei National Laboratory for Physical Science at the Microscale
- School of Life Sciences
- University of Science and Technology of China
- Hefei
- China
| | - Q. F. Li
- State Key Laboratory of Elemento-Organic Chemistry
- Collatorative Innovation Center of Chemical Science and Engineering (Tianjin)
- Nankai University
- Tianjin 300071
- China
| | - A. D. Wang
- Hefei National Laboratory for Physical Science at the Microscale
- School of Life Sciences
- University of Science and Technology of China
- Hefei
- China
| | - J. H. Zhang
- Hefei National Laboratory for Physical Science at the Microscale
- School of Life Sciences
- University of Science and Technology of China
- Hefei
- China
| | - Z. J. Liu
- National Center for Protein Science Shanghai
- Shanghai 201210
- China
| | - J. H. Wu
- Hefei National Laboratory for Physical Science at the Microscale
- School of Life Sciences
- University of Science and Technology of China
- Hefei
- China
| | - X. C. Su
- State Key Laboratory of Elemento-Organic Chemistry
- Collatorative Innovation Center of Chemical Science and Engineering (Tianjin)
- Nankai University
- Tianjin 300071
- China
| | - K. Ruan
- Hefei National Laboratory for Physical Science at the Microscale
- School of Life Sciences
- University of Science and Technology of China
- Hefei
- China
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30
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Barb AW, Subedi GP. An encodable lanthanide binding tag with reduced size and flexibility for measuring residual dipolar couplings and pseudocontact shifts in large proteins. JOURNAL OF BIOMOLECULAR NMR 2016; 64:75-85. [PMID: 26728077 PMCID: PMC4884023 DOI: 10.1007/s10858-015-0009-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 12/28/2015] [Indexed: 05/03/2023]
Abstract
Metal ions serve important roles in structural biology applications from long-range perturbations seen in magnetic resonance experiments to electron-dense signatures in X-ray crystallography data; however, the metal ion must be secured in a molecular framework to achieve the maximum benefit. Polypeptide-based lanthanide-binding tags (LBTs) represent one option that can be directly encoded within a recombinant protein expression construct. However, LBTs often exhibit significant mobility relative to the target molecule. Here we report the characterization of improved LBTs sequences for insertion into a protein loop. These LBTs were inserted to connect two parallel alpha helices of an immunoglobulin G (IgG)-binding Z domain platform. Variants A and B bound Tb(3+) with high affinity (0.70 and 0.13 μM, respectively) and displayed restricted LBT motion. Compared to the parent construct, the metal-bound A experienced a 2.5-fold reduction in tag motion as measured by magnetic field-induced residual dipolar couplings and was further studied in a 72.2 kDa complex with the human IgG1 fragment crystallizable (IgG1 Fc) glycoprotein. The appearance of both pseudo-contact shifts (-0.221 to 0.081 ppm) and residual dipolar couplings (-7.6 to 14.3 Hz) of IgG1 Fc resonances in the IgG1 Fc:(variant A:Tb(3+))2 complex indicated structural restriction of the LBT with respect to the Fc. These studies highlight the applicability of improved LBT sequences with reduced mobility to probe the structure of macromolecular systems.
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Affiliation(s)
- Adam W Barb
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, 2214 Molecular Biology Building, Ames, IA, 50011, USA.
| | - Ganesh P Subedi
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, 2214 Molecular Biology Building, Ames, IA, 50011, USA
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31
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Lee MD, Dennis ML, Swarbrick JD, Graham B. Enantiomeric two-armed lanthanide-binding tags for complementary effects in paramagnetic NMR spectroscopy. Chem Commun (Camb) 2016; 52:7954-7. [DOI: 10.1039/c6cc02325h] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
A new pair of two-armed lanthanide-binding tags provide distinct sets of structural restraints when attached to the same site of a protein.
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Affiliation(s)
- Michael D. Lee
- Monash Institute of Pharmaceutical Sciences
- Monash University
- Parkville
- Australia
| | - Matthew L. Dennis
- Monash Institute of Pharmaceutical Sciences
- Monash University
- Parkville
- Australia
- CSIRO Biosciences Program
| | - James D. Swarbrick
- Monash Institute of Pharmaceutical Sciences
- Monash University
- Parkville
- Australia
| | - Bim Graham
- Monash Institute of Pharmaceutical Sciences
- Monash University
- Parkville
- Australia
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32
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Yang F, Wang X, Pan BB, Su XC. Single-armed phenylsulfonated pyridine derivative of DOTA is rigid and stable paramagnetic tag in protein analysis. Chem Commun (Camb) 2016; 52:11535-11538. [DOI: 10.1039/c6cc06114a] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
Single-armed DOTA-like phenylsulfonated pyridine derivatives are rigid and stable paramagnetic tags for site-specific labelling of proteins. The respective protein conjugates yield valuable long-range structural restraints for proteins.
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Affiliation(s)
- Feng Yang
- State Key Laboratory of Elemento-Organic Chemistry
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin)
- Nankai University
- Tianjin 300071
- China
| | - Xiao Wang
- State Key Laboratory of Elemento-Organic Chemistry
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin)
- Nankai University
- Tianjin 300071
- China
| | - Bin-Bin Pan
- State Key Laboratory of Elemento-Organic Chemistry
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin)
- Nankai University
- Tianjin 300071
- China
| | - Xun-Cheng Su
- State Key Laboratory of Elemento-Organic Chemistry
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin)
- Nankai University
- Tianjin 300071
- China
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33
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Pseudocontact Shift-Driven Iterative Resampling for 3D Structure Determinations of Large Proteins. J Mol Biol 2016; 428:522-32. [DOI: 10.1016/j.jmb.2016.01.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 01/08/2016] [Accepted: 01/08/2016] [Indexed: 01/23/2023]
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34
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Abdelkader EH, Yao X, Feintuch A, Adams LA, Aurelio L, Graham B, Goldfarb D, Otting G. Pulse EPR-enabled interpretation of scarce pseudocontact shifts induced by lanthanide binding tags. JOURNAL OF BIOMOLECULAR NMR 2016; 64:39-51. [PMID: 26597990 DOI: 10.1007/s10858-015-0003-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 11/17/2015] [Indexed: 06/05/2023]
Abstract
Pseudocontact shifts (PCS) induced by tags loaded with paramagnetic lanthanide ions provide powerful long-range structure information, provided the location of the metal ion relative to the target protein is known. Usually, the metal position is determined by fitting the magnetic susceptibility anisotropy (Δχ) tensor to the 3D structure of the protein in an 8-parameter fit, which requires a large set of PCSs to be reliable. In an alternative approach, we used multiple Gd(3+)-Gd(3+) distances measured by double electron-electron resonance (DEER) experiments to define the metal position, allowing Δχ-tensor determinations from more robust 5-parameter fits that can be performed with a relatively sparse set of PCSs. Using this approach with the 32 kDa E. coli aspartate/glutamate binding protein (DEBP), we demonstrate a structural transition between substrate-bound and substrate-free DEBP, supported by PCSs generated by C3-Tm(3+) and C3-Tb(3+) tags attached to a genetically encoded p-azidophenylalanine residue. The significance of small PCSs was magnified by considering the difference between the chemical shifts measured with Tb(3+) and Tm(3+) rather than involving a diamagnetic reference. The integrative sparse data approach developed in this work makes poorly soluble proteins of limited stability amenable to structural studies in solution, without having to rely on cysteine mutations for tag attachment.
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Affiliation(s)
- Elwy H Abdelkader
- Research School of Chemistry, Australian National University, Canberra, ACT, 2601, Australia
| | - Xuejun Yao
- Research School of Chemistry, Australian National University, Canberra, ACT, 2601, Australia
| | - Akiva Feintuch
- Department of Chemical Physics, Weizmann Institute of Science, 76100, Rehovot, Israel
| | - Luke A Adams
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Luigi Aurelio
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Bim Graham
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia
| | - Daniella Goldfarb
- Department of Chemical Physics, Weizmann Institute of Science, 76100, Rehovot, Israel
| | - Gottfried Otting
- Research School of Chemistry, Australian National University, Canberra, ACT, 2601, Australia.
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35
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Quesne MG, Borowski T, de Visser SP. Quantum Mechanics/Molecular Mechanics Modeling of Enzymatic Processes: Caveats and Breakthroughs. Chemistry 2015; 22:2562-81. [PMID: 26696271 DOI: 10.1002/chem.201503802] [Citation(s) in RCA: 113] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Indexed: 11/08/2022]
Abstract
Nature has developed large groups of enzymatic catalysts with the aim to transfer substrates into useful products, which enables biosystems to perform all their natural functions. As such, all biochemical processes in our body (we drink, we eat, we breath, we sleep, etc.) are governed by enzymes. One of the problems associated with research on biocatalysts is that they react so fast that details of their reaction mechanisms cannot be obtained with experimental work. In recent years, major advances in computational hardware and software have been made and now large (bio)chemical systems can be studied using accurate computational techniques. One such technique is the quantum mechanics/molecular mechanics (QM/MM) technique, which has gained major momentum in recent years. Unfortunately, it is not a black-box method that is easily applied, but requires careful set-up procedures. In this work we give an overview on the technical difficulties and caveats of QM/MM and discuss work-protocols developed in our groups for running successful QM/MM calculations.
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Affiliation(s)
- Matthew G Quesne
- Jerzy Haber Institute of Catalysis and Surface Chemistry of the, Polish Academy of Sciences, Niezapominajek 8, 30-239, Krakow, Poland. .,Manchester Institute of Biotechnology and, School of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK.
| | - Tomasz Borowski
- Jerzy Haber Institute of Catalysis and Surface Chemistry of the, Polish Academy of Sciences, Niezapominajek 8, 30-239, Krakow, Poland.
| | - Sam P de Visser
- Manchester Institute of Biotechnology and, School of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK.
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