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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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Rydzewski J, Walczewska-Szewc K, Czach S, Nowak W, Kuczera K. Enhancing the Inhomogeneous Photodynamics of Canonical Bacteriophytochrome. J Phys Chem B 2022; 126:2647-2657. [PMID: 35357137 PMCID: PMC9014414 DOI: 10.1021/acs.jpcb.2c00131] [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] [Indexed: 11/28/2022]
Abstract
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The ability of phytochromes
to act as photoswitches in plants and
microorganisms depends on interactions between a bilin-like chromophore
and a host protein. The interconversion occurs between the spectrally
distinct red (Pr) and far-red (Pfr) conformers. This conformational
change is triggered by the photoisomerization of the chromophore D-ring
pyrrole. In this study, as a representative example of a phytochrome-bilin
system, we consider biliverdin IXα (BV) bound to bacteriophytochrome
(BphP) from Deinococcus radiodurans. In the absence
of light, we use an enhanced sampling molecular dynamics (MD) method
to overcome the photoisomerization energy barrier. We find that the
calculated free energy (FE) barriers between essential metastable
states agree with spectroscopic results. We show that the enhanced
dynamics of the BV chromophore in BphP contributes to triggering nanometer-scale
conformational movements that propagate by two experimentally determined
signal transduction pathways. Most importantly, we describe how the
metastable states enable a thermal transition known as the dark reversion
between Pfr and Pr, through a previously unknown intermediate state
of Pfr. We present the heterogeneity of temperature-dependent Pfr
states at the atomistic level. This work paves a way toward understanding
the complete mechanism of the photoisomerization of a bilin-like chromophore
in phytochromes.
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Affiliation(s)
- Jakub Rydzewski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100, Torun, Poland
| | - Katarzyna Walczewska-Szewc
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100, Torun, Poland
| | - Sylwia Czach
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100, Torun, Poland
| | - Wieslaw Nowak
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100, Torun, Poland
| | - Krzysztof Kuczera
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66047, United States.,Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
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3
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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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4
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Ritacco I, Saltalamacchia A, Spinello A, Ippoliti E, Magistrato A. All-Atom Simulations Disclose How Cytochrome Reductase Reshapes the Substrate Access/Egress Routes of Its Partner CYP450s. J Phys Chem Lett 2020; 11:1189-1193. [PMID: 31986051 DOI: 10.1021/acs.jpclett.9b03798] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Cytochromes P450 enzymes (CYP450s) promote the oxidative metabolism of a variety of substrates via the electrons supplied by the cytochrome P450 reductase (CPR) and upon formation of a CPR/CYP450 adduct. In spite of the pivotal regulatory importance of this process, the impact of CPR binding on the functional properties of its partner CYP450 remains elusive. By performing multiple microsecond-long all-atom molecular dynamics simulations of a 520 000-atom model of a CPR/CYP450 adduct embedded in a membrane mimic, we disclose the molecular terms for their interactions, considering the aromatase (HA) enzyme as a proxy of the CYP450 family. Our study strikingly unveils that CPR binding alters HA's functional motions, bolstering a change in the shape and type of the channels traveled by substrates/products during their access/egress to/from the enzyme's active site. Our outcomes unprecedentedly contribute to extricate the many entangled facets of the CYP450 metabolon, redrafting its intricate panorama from an atomic-level perspective.
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Affiliation(s)
- Ida Ritacco
- CNR-IOM c/o SISSA , via Bonomea 265 , 34136 Trieste , Italy
| | | | | | - Emiliano Ippoliti
- IAS-5/INM-9 Computational Biomedicine Institute and JARA-HPC , Forschungszentrum Jülich , Wilhelm-Johnen-Straße , 52425 Jülich , Germany
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5
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Rydzewski J, Valsson O. Finding multiple reaction pathways of ligand unbinding. J Chem Phys 2019; 150:221101. [DOI: 10.1063/1.5108638] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Affiliation(s)
- Jakub Rydzewski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87–100 Torun, Poland
| | - Omar Valsson
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
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6
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Nunes-Alves A, Zuckerman DM, Arantes GM. Escape of a Small Molecule from Inside T4 Lysozyme by Multiple Pathways. Biophys J 2019. [PMID: 29539393 DOI: 10.1016/j.bpj.2018.01.014] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The T4 lysozyme L99A mutant is often used as a model system to study small-molecule binding to proteins, but pathways for ligand entry and exit from the buried binding site and the associated protein conformational changes have not been fully resolved. Here, molecular dynamics simulations were employed to model benzene exit from its binding cavity using the weighted ensemble (WE) approach to enhance sampling of low-probability unbinding trajectories. Independent WE simulations revealed four pathways for benzene exit, which correspond to transient tunnels spontaneously formed in previous simulations of apo T4 lysozyme. Thus, benzene unbinding occurs through multiple pathways partially created by intrinsic protein structural fluctuations. Motions of several α-helices and side chains were involved in ligand escape from metastable microstates. WE simulations also provided preliminary estimates of rate constants for each exit pathway. These results complement previous works and provide a semiquantitative characterization of pathway heterogeneity for binding of small molecules to proteins.
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Affiliation(s)
- Ariane Nunes-Alves
- Department of Biochemistry, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Daniel M Zuckerman
- Department of Biomedical Engineering, School of Medicine, Oregon Health & Science University, Portland, Oregon.
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7
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Follmer AH, Mahomed M, Goodin DB, Poulos TL. Substrate-Dependent Allosteric Regulation in Cytochrome P450cam (CYP101A1). J Am Chem Soc 2018; 140:16222-16228. [DOI: 10.1021/jacs.8b09441] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Alec H. Follmer
- Departments of Molecular Biology and Biochemistry, Pharmaceutical Sciences, and Chemistry, University of California, Irvine, California 92697-3900, United States
| | - Mavish Mahomed
- 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
| | - Thomas L. Poulos
- Departments of Molecular Biology and Biochemistry, Pharmaceutical Sciences, and Chemistry, University of California, Irvine, California 92697-3900, United States
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8
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Rydzewski J, Jakubowski R, Nowak W, Grubmüller H. Kinetics of Huperzine A Dissociation from Acetylcholinesterase via Multiple Unbinding Pathways. J Chem Theory Comput 2018; 14:2843-2851. [PMID: 29715428 DOI: 10.1021/acs.jctc.8b00173] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The dissociation of huperzine A (hupA) from Torpedo californica acetylcholinesterase ( TcAChE) was investigated by 4 μs unbiased and biased all-atom molecular dynamics (MD) simulations in explicit solvent. We performed our study using memetic sampling (MS) for the determination of reaction pathways (RPs), metadynamics to calculate free energy, and maximum-likelihood estimation (MLE) to recover kinetic rates from unbiased MD simulations. Our simulations suggest that the dissociation of hupA occurs mainly via two RPs: a front door along the axis of the active-site gorge (pwf) and through a new transient side door (pws), i.e., formed by the Ω-loop (residues 67-94 of TcAChE). An analysis of the inhibitor unbinding along the RPs suggests that pws is opened transiently after hupA and the Ω-loop reach a low free-energy transition state characterized by the orientation of the pyridone group of the inhibitor directed toward the Ω-loop plane. Unlike pws, pwf does not require large structural changes in TcAChE to be accessible. The estimated free energies and rates agree well with available experimental data. The dissociation rates along the unbinding pathways are similar, suggesting that the dissociation of hupA along pws is likely to be relevant. This indicates that perturbations to hupA- TcAChE interactions could potentially induce pathway hopping. In summary, our results characterize the slow-onset inhibition of TcAChE by hupA, which may provide the structural and energetic bases for the rational design of the next-generation slow-onset inhibitors with optimized pharmacokinetic properties for the treatment of Alzheimer's disease.
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Affiliation(s)
- J Rydzewski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University , Grudziadzka 5 , 87-100 Toruń , Poland
| | - R Jakubowski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University , Grudziadzka 5 , 87-100 Toruń , Poland.,Centre of New Technologies, University of Warsaw , Banacha 2c , 02-097 Warsaw , Poland
| | - W Nowak
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University , Grudziadzka 5 , 87-100 Toruń , Poland
| | - H Grubmüller
- Max Planck Institute for Biophysical Chemistry , Am Faßberg 11 , 37077 Göttingen , Germany
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9
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Rare-event sampling in ligand diffusion. Phys Life Rev 2017; 22-23:85-87. [DOI: 10.1016/j.plrev.2017.08.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 08/27/2017] [Indexed: 01/06/2023]
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