1
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Han CT, Nguyen KDQ, Berkow MW, Hussain S, Kiani A, Kinnebrew M, Idso MN, Baxter N, Chang E, Aye E, Winslow E, Rahman M, Seppälä S, O'Malley MA, Chmelka BF, Mertz B, Han S. Lipid membrane mimetics and oligomerization tune functional properties of proteorhodopsin. Biophys J 2023; 122:168-179. [PMID: 36352784 PMCID: PMC9822798 DOI: 10.1016/j.bpj.2022.11.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 08/01/2022] [Accepted: 11/07/2022] [Indexed: 11/10/2022] Open
Abstract
The functional properties of proteorhodopsin (PR) have been found to be strongly modulated by oligomeric distributions and lipid membrane mimetics. This study aims to distinguish and explain their effects by investigating how oligomer formation impacts PR's function of proton transport in lipid-based membrane mimetic environments. We find that PR forms stable hexamers and pentamers in both E. coli membranes and synthetic liposomes. Compared with the monomers, the photocycle kinetics of PR oligomers is ∼2 and ∼4.5 times slower for transitions between the K and M and the M and N photointermediates, respectively, indicating that oligomerization significantly slows PR's rate of proton transport in liposomes. In contrast, the apparent pKa of the key proton acceptor residue D97 (pKaD97) of liposome-embedded PR persists at 6.2-6.6, regardless of cross-protomer modulation of D97, suggesting that the liposome environment helps maintain PR's functional activity at neutral pH. By comparison, when extracted directly from E. coli membranes into styrene-maleic acid lipid particles, the pKaD97 of monomer-enriched E50Q PR drastically increases to 8.9, implying that there is a very low active PR population at neutral pH to engage in PR's photocycle. These findings demonstrate that oligomerization impacts PR's photocycle kinetics, while lipid-based membrane mimetics strongly affect PR's active population via different mechanisms.
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Affiliation(s)
- Chung-Ta Han
- Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, California
| | - Khanh Dinh Quoc Nguyen
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California
| | - Maxwell W Berkow
- Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, California
| | - Sunyia Hussain
- Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, California
| | - Ahmad Kiani
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia
| | - Maia Kinnebrew
- College of Creative Studies, Biology Department, University of California, Santa Barbara, Santa Barbara, California
| | - Matthew N Idso
- Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, California
| | - Naomi Baxter
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California
| | - Evelyn Chang
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California
| | - Emily Aye
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California
| | - Elsa Winslow
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California
| | - Mohammad Rahman
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia
| | - Susanna Seppälä
- Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, California
| | - Michelle A O'Malley
- Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, California
| | - Bradley F Chmelka
- Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, California
| | - Blake Mertz
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia
| | - Songi Han
- Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, California; Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California.
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2
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Astashkin R, Kovalev K, Bukhdruker S, Vaganova S, Kuzmin A, Alekseev A, Balandin T, Zabelskii D, Gushchin I, Royant A, Volkov D, Bourenkov G, Koonin E, Engelhard M, Bamberg E, Gordeliy V. Structural insights into light-driven anion pumping in cyanobacteria. Nat Commun 2022; 13:6460. [PMID: 36309497 PMCID: PMC9617919 DOI: 10.1038/s41467-022-34019-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 10/11/2022] [Indexed: 12/25/2022] Open
Abstract
Transmembrane ion transport is a key process in living cells. Active transport of ions is carried out by various ion transporters including microbial rhodopsins (MRs). MRs perform diverse functions such as active and passive ion transport, photo-sensing, and others. In particular, MRs can pump various monovalent ions like Na+, K+, Cl-, I-, NO3-. The only characterized MR proposed to pump sulfate in addition to halides belongs to the cyanobacterium Synechocystis sp. PCC 7509 and is named Synechocystis halorhodopsin (SyHR). The structural study of SyHR may help to understand what makes an MR pump divalent ions. Here we present the crystal structure of SyHR in the ground state, the structure of its sulfate-bound form as well as two photoreaction intermediates, the K and O states. These data reveal the molecular origin of the unique properties of the protein (exceptionally strong chloride binding and proposed pumping of divalent anions) and sheds light on the mechanism of anion release and uptake in cyanobacterial halorhodopsins. The unique properties of SyHR highlight its potential as an optogenetics tool and may help engineer different types of anion pumps with applications in optogenetics.
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Affiliation(s)
- R. Astashkin
- grid.450307.50000 0001 0944 2786Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale (IBS), Grenoble, France
| | - K. Kovalev
- grid.475756.20000 0004 0444 5410European Molecular Biology Laboratory, Hamburg unit c/o DESY, Hamburg, Germany
| | - S. Bukhdruker
- grid.5398.70000 0004 0641 6373European Synchrotron Radiation Facility Grenoble, Grenoble, France ,grid.8385.60000 0001 2297 375XInstitute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany ,grid.8385.60000 0001 2297 375XJuStruct: Jülich Center for Structural Biology, Forschungszentrum Jülich, Jülich, Germany
| | - S. Vaganova
- grid.8385.60000 0001 2297 375XInstitute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany ,grid.8385.60000 0001 2297 375XJuStruct: Jülich Center for Structural Biology, Forschungszentrum Jülich, Jülich, Germany
| | - A. Kuzmin
- grid.18763.3b0000000092721542Research Center for Molecular Mechanisms of Aging and Age-related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - A. Alekseev
- grid.18763.3b0000000092721542Research Center for Molecular Mechanisms of Aging and Age-related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - T. Balandin
- grid.8385.60000 0001 2297 375XInstitute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany ,grid.8385.60000 0001 2297 375XJuStruct: Jülich Center for Structural Biology, Forschungszentrum Jülich, Jülich, Germany
| | - D. Zabelskii
- grid.434729.f0000 0004 0590 2900European XFEL GmbH, Schenefeld, Germany
| | - I. Gushchin
- grid.18763.3b0000000092721542Research Center for Molecular Mechanisms of Aging and Age-related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - A. Royant
- grid.450307.50000 0001 0944 2786Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale (IBS), Grenoble, France ,grid.5398.70000 0004 0641 6373European Synchrotron Radiation Facility Grenoble, Grenoble, France
| | - D. Volkov
- grid.8385.60000 0001 2297 375XInstitute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany ,grid.8385.60000 0001 2297 375XJuStruct: Jülich Center for Structural Biology, Forschungszentrum Jülich, Jülich, Germany
| | - G. Bourenkov
- grid.475756.20000 0004 0444 5410European Molecular Biology Laboratory, Hamburg unit c/o DESY, Hamburg, Germany
| | - E. Koonin
- grid.419234.90000 0004 0604 5429National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD USA
| | - M. Engelhard
- grid.418441.c0000 0004 0491 3333Department Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany
| | - E. Bamberg
- grid.419494.50000 0001 1018 9466Max Planck Institute of Biophysics, Frankfurt am Main, Germany
| | - V. Gordeliy
- grid.450307.50000 0001 0944 2786Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale (IBS), Grenoble, France ,grid.8385.60000 0001 2297 375XInstitute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany ,grid.8385.60000 0001 2297 375XJuStruct: Jülich Center for Structural Biology, Forschungszentrum Jülich, Jülich, Germany
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3
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Qiu Y, Smith DGA, Stern CD, Feng M, Jang H, Wang LP. Driving torsion scans with wavefront propagation. J Chem Phys 2020; 152:244116. [PMID: 32610969 DOI: 10.1063/5.0009232] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The parameterization of torsional/dihedral angle potential energy terms is a crucial part of developing molecular mechanics force fields. Quantum mechanical (QM) methods are often used to provide samples of the potential energy surface (PES) for fitting the empirical parameters in these force field terms. To ensure that the sampled molecular configurations are thermodynamically feasible, constrained QM geometry optimizations are typically carried out, which relax the orthogonal degrees of freedom while fixing the target torsion angle(s) on a grid of values. However, the quality of results and computational cost are affected by various factors on a non-trivial PES, such as dependence on the chosen scan direction and the lack of efficient approaches to integrate results started from multiple initial guesses. In this paper, we propose a systematic and versatile workflow called TorsionDrive to generate energy-minimized structures on a grid of torsion constraints by means of a recursive wavefront propagation algorithm, which resolves the deficiencies of conventional scanning approaches and generates higher quality QM data for force field development. The capabilities of our method are presented for multi-dimensional scans and multiple initial guess structures, and an integration with the MolSSI QCArchive distributed computing ecosystem is described. The method is implemented in an open-source software package that is compatible with many QM software packages and energy minimization codes.
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Affiliation(s)
- Yudong Qiu
- Department of Chemistry, UC Davis, Davis, California 95616, USA
| | - Daniel G A Smith
- The Molecular Sciences Software Institute, Blacksburg, Virginia 24060, USA
| | - Chaya D Stern
- Computational and Systems Biology Program, Sloan-Kettering Institute, New York, New York 10065, USA
| | - Mudong Feng
- Department of Chemistry and Biochemistry, UC San Diego, La Jolla, California 92093, USA
| | - Hyesu Jang
- Department of Chemistry, UC Davis, Davis, California 95616, USA
| | - Lee-Ping Wang
- Department of Chemistry, UC Davis, Davis, California 95616, USA
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4
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Li W. Residue-Residue Mutual Work Analysis of Retinal-Opsin Interaction in Rhodopsin: Implications for Protein-Ligand Binding. J Chem Theory Comput 2020; 16:1834-1842. [PMID: 31972074 DOI: 10.1021/acs.jctc.9b01035] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Energetic contributions at the single-residue level for retinal-opsin interactions in rhodopsin were studied by combining molecular dynamics simulations, transition path sampling, and a newly developed energy decomposition approach. The virtual work at an infinitesimal time interval was decomposed into the work components on one residue due to its interaction with another residue, which were then averaged over the transition path ensemble along a proposed reaction coordinate. Such residue-residue mutual work analysis on 62 residues within the active center of rhodopsin resulted in a very sparse interaction matrix, which is generally not symmetric but antisymmetric to some extent. Fourteen residues were identified to be major players in retinal relaxation along a plausible pathway from bathorhodopsin to the blue-shifted intermediate, which is in good agreement with an existing NMR study. Based on the matrix of mutual work, a comprehensive network was constructed to provide detailed insights into the chromophore-protein interaction from a viewpoint of energy flow.
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Affiliation(s)
- Wenjin Li
- Institute for Advanced Study, Shenzhen University, Shenzhen, China
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5
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Ryazantsev MN, Nikolaev DM, Struts AV, Brown MF. Quantum Mechanical and Molecular Mechanics Modeling of Membrane-Embedded Rhodopsins. J Membr Biol 2019; 252:425-449. [PMID: 31570961 DOI: 10.1007/s00232-019-00095-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 09/10/2019] [Indexed: 12/20/2022]
Abstract
Computational chemistry provides versatile methods for studying the properties and functioning of biological systems at different levels of precision and at different time scales. The aim of this article is to review the computational methodologies that are applicable to rhodopsins as archetypes for photoactive membrane proteins that are of great importance both in nature and in modern technologies. For each class of computational techniques, from methods that use quantum mechanics for simulating rhodopsin photophysics to less-accurate coarse-grained methodologies used for long-scale protein dynamics, we consider possible applications and the main directions for improvement.
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Affiliation(s)
- Mikhail N Ryazantsev
- Institute of Chemistry, Saint Petersburg State University, 26 Universitetskii pr, Saint Petersburg, Russia, 198504
| | - Dmitrii M Nikolaev
- Saint-Petersburg Academic University - Nanotechnology Research and Education Centre RAS, Saint Petersburg, Russia, 194021
| | - Andrey V Struts
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, USA.,Laboratory of Biomolecular NMR, Saint Petersburg State University, Saint Petersburg, Russia, 199034
| | - Michael F Brown
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, USA. .,Department of Physics, University of Arizona, Tucson, AZ, 85721, USA.
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6
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Navidi M, Yadav S, Struts AV, Brown MF, Nesnas N. Synthesis of 9-CD 3-9- cis-Retinal Cofactor of Isorhodopsin. Tetrahedron Lett 2018; 59:4521-4524. [PMID: 30692701 DOI: 10.1016/j.tetlet.2018.11.034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We report the synthesis of 9-CD3-9-cis-retinal via a six-step procedure from β-ionone. The steps involve an initial deuteration of the methyl ketone of β-ionone followed by two consecutive Horner-Wadsworth-Emmons (HWE) coupling reactions and their corresponding DIBAL reductions. A final oxidation of the allylic alcohol of the retinol leads to the target compound. This deuterium labeled retinoid is an important cofactor for studying protein-retinoid interactions in isorhodopsin.
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Affiliation(s)
- Mozhgan Navidi
- Department of Biomedical & Chemical Engineering & Sciences, Florida Institute of Technology, Melbourne, Florida 32901, USA
| | - Shreya Yadav
- Department of Biomedical & Chemical Engineering & Sciences, Florida Institute of Technology, Melbourne, Florida 32901, USA
| | - Andrey V Struts
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721, USA
| | - Michael F Brown
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721, USA
| | - Nasri Nesnas
- Department of Biomedical & Chemical Engineering & Sciences, Florida Institute of Technology, Melbourne, Florida 32901, USA
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7
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Faramarzi S, Feng J, Mertz B. Allosteric Effects of the Proton Donor on the Microbial Proton Pump Proteorhodopsin. Biophys J 2018; 115:1240-1250. [PMID: 30219284 DOI: 10.1016/j.bpj.2018.08.028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 08/21/2018] [Accepted: 08/22/2018] [Indexed: 11/17/2022] Open
Abstract
Proteorhodopsin (PR) is a microbial proton pump that is ubiquitous in marine environments and may play an important role in the oceanic carbon cycle. Photoisomerization of the retinal chromophore in PR leads to a series of proton transfers between specific acidic amino acid residues and the Schiff base of retinal, culminating in a proton motive force to facilitate ATP synthesis. The proton donor in a similar retinal protein, bacteriorhodopsin, acts as a latch to allow the influx of bulk water. However, it is unclear if the proton donor in PR, E108, utilizes the same latch mechanism to become internally hydrated. Here, we used molecular dynamics simulations to model the changes in internal hydration of the blue variant of PR during photoactivation with the proton donor in protonated and deprotonated states. We find that there is a stark contrast in the levels of internal hydration of the cytoplasmic half of PR based on the protonation state of E108. Instead of a latch mechanism, deprotonation of E108 acts as a gate, taking advantage of a nearby polar residue (S61) to promote the formation of a stable water wire from bulk cytoplasm to the retinal-binding pocket over hundreds of nanoseconds. No large-scale conformational changes occur in PR over the microsecond timescale. This subtle yet clear difference in the effect of deprotonation of the proton donor in PR may help explain why the photointermediates that involve the proton donor (i.e., M and N states) have timescales that are orders of magnitude different from the archaeal proton pump, bacteriorhodopsin. In general, our study highlights the importance of understanding how structural fluctuations lead to differences in the way that retinal proteins accomplish the same task.
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Affiliation(s)
- Sadegh Faramarzi
- C. Eugene Department of Chemistry, West Virginia University, Morgantown, West Virginia
| | - Jun Feng
- C. Eugene Department of Chemistry, West Virginia University, Morgantown, West Virginia
| | - Blake Mertz
- C. Eugene Department of Chemistry, West Virginia University, Morgantown, West Virginia.
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8
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El Hage K, Brickel S, Hermelin S, Gaulier G, Schmidt C, Bonacina L, van Keulen SC, Bhattacharyya S, Chergui M, Hamm P, Rothlisberger U, Wolf JP, Meuwly M. Implications of short time scale dynamics on long time processes. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2017; 4:061507. [PMID: 29308419 PMCID: PMC5741438 DOI: 10.1063/1.4996448] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 09/15/2017] [Indexed: 05/02/2023]
Abstract
This review provides a comprehensive overview of the structural dynamics in topical gas- and condensed-phase systems on multiple length and time scales. Starting from vibrationally induced dissociation of small molecules in the gas phase, the question of vibrational and internal energy redistribution through conformational dynamics is further developed by considering coupled electron/proton transfer in a model peptide over many orders of magnitude. The influence of the surrounding solvent is probed for electron transfer to the solvent in hydrated I-. Next, the dynamics of a modified PDZ domain over many time scales is analyzed following activation of a photoswitch. The hydration dynamics around halogenated amino acid side chains and their structural dynamics in proteins are relevant for iodinated TyrB26 insulin. Binding of nitric oxide to myoglobin is a process for which experimental and computational analyses have converged to a common view which connects rebinding time scales and the underlying dynamics. Finally, rhodopsin is a paradigmatic system for multiple length- and time-scale processes for which experimental and computational methods provide valuable insights into the functional dynamics. The systems discussed here highlight that for a comprehensive understanding of how structure, flexibility, energetics, and dynamics contribute to functional dynamics, experimental studies in multiple wavelength regions and computational studies including quantum, classical, and more coarse grained levels are required.
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Affiliation(s)
- Krystel El Hage
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland
| | - Sebastian Brickel
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland
| | - Sylvain Hermelin
- Department of Applied Physics (GAP), University of Geneva, 22 Ch. de Pinchat, 1211 Geneva 4, Switzerland
| | - Geoffrey Gaulier
- Department of Applied Physics (GAP), University of Geneva, 22 Ch. de Pinchat, 1211 Geneva 4, Switzerland
| | - Cédric Schmidt
- Department of Applied Physics (GAP), University of Geneva, 22 Ch. de Pinchat, 1211 Geneva 4, Switzerland
| | - Luigi Bonacina
- Department of Applied Physics (GAP), University of Geneva, 22 Ch. de Pinchat, 1211 Geneva 4, Switzerland
| | - Siri C van Keulen
- Institute of Chemical Sciences and Engineering, EPFL, Lausanne, Switzerland
| | | | - Majed Chergui
- Institute of Chemical Sciences and Engineering, EPFL, Lausanne, Switzerland
| | - Peter Hamm
- Department of Chemistry, University of Zurich, Zurich, Switzerland
| | | | - Jean-Pierre Wolf
- Department of Applied Physics (GAP), University of Geneva, 22 Ch. de Pinchat, 1211 Geneva 4, Switzerland
| | - Markus Meuwly
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland
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9
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Kazmin R, Rose A, Szczepek M, Elgeti M, Ritter E, Piechnick R, Hofmann KP, Scheerer P, Hildebrand PW, Bartl FJ. The Activation Pathway of Human Rhodopsin in Comparison to Bovine Rhodopsin. J Biol Chem 2015; 290:20117-27. [PMID: 26105054 DOI: 10.1074/jbc.m115.652172] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Indexed: 11/06/2022] Open
Abstract
Rhodopsin, the photoreceptor of rod cells, absorbs light to mediate the first step of vision by activating the G protein transducin (Gt). Several human diseases, such as retinitis pigmentosa or congenital night blindness, are linked to rhodopsin malfunctions. Most of the corresponding in vivo studies and structure-function analyses (e.g. based on protein x-ray crystallography or spectroscopy) have been carried out on murine or bovine rhodopsin. Because these rhodopsins differ at several amino acid positions from human rhodopsin, we conducted a comprehensive spectroscopic characterization of human rhodopsin in combination with molecular dynamics simulations. We show by FTIR and UV-visible difference spectroscopy that the light-induced transformations of the early photointermediates are very similar. Significant differences between the pigments appear with formation of the still inactive Meta I state and the transition to active Meta II. However, the conformation of Meta II and its activity toward the G protein are essentially the same, presumably reflecting the evolutionary pressure under which the active state has developed. Altogether, our results show that although the basic activation pathways of human and bovine rhodopsin are similar, structural deviations exist in the inactive conformation and during receptor activation, even between closely related rhodopsins. These differences between the well studied bovine or murine rhodopsins and human rhodopsin have to be taken into account when the influence of point mutations on the activation pathway of human rhodopsin are investigated using the bovine or murine rhodopsin template sequences.
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Affiliation(s)
- Roman Kazmin
- From the Institut für Medizinische Physik und Biophysik, Charité-Universitätsmedizin Berlin, Institut für Biologie, Experimentelle Biophysik, Humboldt-Universität zu Berlin, 10115 Berlin, Germany, and
| | - Alexander Rose
- From the Institut für Medizinische Physik und Biophysik, Charité-Universitätsmedizin Berlin, AG ProteInformatics, Charitéplatz 1, 10117 Berlin, Germany
| | - Michal Szczepek
- From the Institut für Medizinische Physik und Biophysik, Charité-Universitätsmedizin Berlin, AG Protein X-ray Crystallography and Signal Transduction, and
| | - Matthias Elgeti
- From the Institut für Medizinische Physik und Biophysik, Charité-Universitätsmedizin Berlin
| | - Eglof Ritter
- Institut für Biologie, Experimentelle Biophysik, Humboldt-Universität zu Berlin, 10115 Berlin, Germany, and
| | - Ronny Piechnick
- From the Institut für Medizinische Physik und Biophysik, Charité-Universitätsmedizin Berlin
| | - Klaus Peter Hofmann
- From the Institut für Medizinische Physik und Biophysik, Charité-Universitätsmedizin Berlin, Zentrum für Biophysik und Bioinformatik (BPI), Humboldt-Universität zu Berlin, 10115 Berlin, Germany
| | - Patrick Scheerer
- From the Institut für Medizinische Physik und Biophysik, Charité-Universitätsmedizin Berlin, AG Protein X-ray Crystallography and Signal Transduction, and
| | - Peter W Hildebrand
- From the Institut für Medizinische Physik und Biophysik, Charité-Universitätsmedizin Berlin, AG ProteInformatics, Charitéplatz 1, 10117 Berlin, Germany
| | - Franz J Bartl
- From the Institut für Medizinische Physik und Biophysik, Charité-Universitätsmedizin Berlin,
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10
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Structure-Based Biophysical Analysis of the Interaction of Rhodopsin with G Protein and Arrestin. Methods Enzymol 2015; 556:563-608. [DOI: 10.1016/bs.mie.2014.12.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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11
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Mertz B, Feng J, Corcoran C, Neeley B. Explaining the mobility of retinal in activated rhodopsin and opsin. Photochem Photobiol Sci 2015; 14:1952-64. [PMID: 26248892 DOI: 10.1039/c5pp00173k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Computational studies reveal flexibility of the rhodopsin cofactor, retinal, within the protein binding pocket that play a key role in the activated state and regeneration of rhodopsin.
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Affiliation(s)
- Blake Mertz
- The C. Eugene Bennett Department of Chemistry
- West Virginia University
- Morgantown
- USA
| | - Jun Feng
- The C. Eugene Bennett Department of Chemistry
- West Virginia University
- Morgantown
- USA
| | - Conor Corcoran
- The C. Eugene Bennett Department of Chemistry
- West Virginia University
- Morgantown
- USA
| | - Brandon Neeley
- The C. Eugene Bennett Department of Chemistry
- West Virginia University
- Morgantown
- USA
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12
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Leioatts N, Mertz B, Martínez-Mayorga K, Romo TD, Pitman MC, Feller SE, Grossfield A, Brown MF. Retinal ligand mobility explains internal hydration and reconciles active rhodopsin structures. Biochemistry 2014; 53:376-85. [PMID: 24328554 DOI: 10.1021/bi4013947] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Rhodopsin, the mammalian dim-light receptor, is one of the best-characterized G-protein-coupled receptors, a pharmaceutically important class of membrane proteins that has garnered a great deal of attention because of the recent availability of structural information. Yet the mechanism of rhodopsin activation is not fully understood. Here, we use microsecond-scale all-atom molecular dynamics simulations, validated by solid-state (2)H nuclear magnetic resonance spectroscopy, to understand the transition between the dark and metarhodopsin I (Meta I) states. Our analysis of these simulations reveals striking differences in ligand flexibility between the two states. Retinal is much more dynamic in Meta I, adopting an elongated conformation similar to that seen in the recent activelike crystal structures. Surprisingly, this elongation corresponds to both a dramatic influx of bulk water into the hydrophobic core of the protein and a concerted transition in the highly conserved Trp265(6.48) residue. In addition, enhanced ligand flexibility upon light activation provides an explanation for the different retinal orientations observed in X-ray crystal structures of active rhodopsin.
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Affiliation(s)
- Nicholas Leioatts
- Department of Biochemistry and Biophysics, University of Rochester Medical Center , Rochester, New York 14642, United States
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Zhu S, Brown MF, Feller SE. Retinal conformation governs pKa of protonated Schiff base in rhodopsin activation. J Am Chem Soc 2013; 135:9391-8. [PMID: 23701524 PMCID: PMC5176254 DOI: 10.1021/ja4002986] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have explored the relationship between conformational energetics and the protonation state of the Schiff base in retinal, the covalently bound ligand responsible for activating the G protein-coupled receptor rhodopsin, using quantum chemical calculations. Guided by experimental structural determinations and large-scale molecular simulations on this system, we examined rotation about each bond in the retinal polyene chain, for both the protonated and deprotonated states that represent the dark and photoactivated states, respectively. Particular attention was paid to the torsional degrees of freedom that determine the shape of the molecule, and hence its interactions with the protein binding pocket. While most torsional degrees of freedom in retinal are characterized by large energetic barriers that minimize structural fluctuations under physiological temperatures, the C6-C7 dihedral defining the relative orientation of the β-ionone ring to the polyene chain has both modest barrier heights and a torsional energy surface that changes dramatically with protonation of the Schiff base. This surprising coupling between conformational degrees of freedom and protonation state is further quantified by calculations of the pKa as a function of the C6-C7 dihedral angle. Notably, pKa shifts of greater than two units arise from torsional fluctuations observed in molecular dynamics simulations of the full ligand-protein-membrane system. It follows that fluctuations in the protonation state of the Schiff base occur prior to forming the activated MII state. These new results shed light on important mechanistic aspects of retinal conformational changes that are involved in the activation of rhodopsin in the visual process.
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Affiliation(s)
- Shengshuang Zhu
- Department of Chemistry, Wabash College, Crawfordsville IN 47933
| | - Michael F. Brown
- Department of Chemistry and Biochemistry, University of Arizona, Tucson AZ 85721
- Department of Physics, University of Arizona, Tucson AZ 85721
| | - Scott E. Feller
- Department of Chemistry, Wabash College, Crawfordsville IN 47933
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G-protein-coupled receptor structure, ligand binding and activation as studied by solid-state NMR spectroscopy. Biochem J 2013; 450:443-57. [DOI: 10.1042/bj20121644] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
GPCRs (G-protein-coupled receptors) are versatile signalling molecules at the cell surface and make up the largest and most diverse family of membrane receptors in the human genome. They convert a large variety of extracellular stimuli into intracellular responses through the activation of heterotrimeric G-proteins, which make them key regulatory elements in a broad range of normal and pathological processes, and are therefore one of the most important targets for pharmaceutical drug discovery. Knowledge of a GPCR structure enables us to gain a mechanistic insight into its function and dynamics, and further aid rational drug design. Despite intensive research carried out over the last three decades, resolving the structural basis of GPCR function is still a major activity. The crystal structures obtained in the last 5 years provide the first opportunity to understand how protein structure dictates the unique functional properties of these complex signalling molecules. However, owing to the intrinsic hydrophobicity, flexibility and instability of membrane proteins, it is still a challenge to crystallize GPCRs, and, when this is possible, it is no longer in its native membrane environment and no longer without modification. Furthermore, the conformational change of the transmembrane α-helices associated with the structure activation increases the difficulty of capturing the activation state of a GPCR to a higher resolution by X-ray crystallography. On the other hand, solid-state NMR may offer a unique opportunity to study membrane protein structure, ligand binding and activation at atomic resolution in the native membrane environment, as well as described functionally significant dynamics. In the present review, we discuss some recent achievements of solid-state NMR for understanding GPCRs, the largest mammalian proteome at ~1% of the total expressed proteins. Structural information, details of determination, details of ligand conformations and the consequences of ligand binding to initiate activation can all be explored with solid-state NMR.
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Mertz B, Struts AV, Feller SE, Brown MF. Molecular simulations and solid-state NMR investigate dynamical structure in rhodopsin activation. BIOCHIMICA ET BIOPHYSICA ACTA 2012; 1818:241-51. [PMID: 21851809 PMCID: PMC5270601 DOI: 10.1016/j.bbamem.2011.08.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2011] [Revised: 08/01/2011] [Accepted: 08/01/2011] [Indexed: 10/17/2022]
Abstract
Rhodopsin has served as the primary model for studying G protein-coupled receptors (GPCRs)-the largest group in the human genome, and consequently a primary target for pharmaceutical development. Understanding the functions and activation mechanisms of GPCRs has proven to be extraordinarily difficult, as they are part of a complex signaling cascade and reside within the cell membrane. Although X-ray crystallography has recently solved several GPCR structures that may resemble the activated conformation, the dynamics and mechanism of rhodopsin activation continue to remain elusive. Notably solid-state ((2))H NMR spectroscopy provides key information pertinent to how local dynamics of the retinal ligand change during rhodopsin activation. When combined with molecular mechanics simulations of proteolipid membranes, a new paradigm for the rhodopsin activation process emerges. Experiment and simulation both suggest that retinal isomerization initiates the rhodopsin photocascade to yield not a single activated structure, but rather an ensemble of activated conformational states. This article is part of a Special Issue entitled: Membrane protein structure and function.
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Affiliation(s)
- Blake Mertz
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | - Andrey V. Struts
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
- Department of Medical Physics, St. Petersburg State Medical University, St. Petersburg 194100, Russia
| | - Scott E. Feller
- Department of Chemistry, Wabash College, Crawfordsville, IN 47933, USA
| | - Michael F. Brown
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
- Department of Physics, University of Arizona, Tucson, AZ 85721, USA
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