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de Grip WJ, Ganapathy S. Rhodopsins: An Excitingly Versatile Protein Species for Research, Development and Creative Engineering. Front Chem 2022; 10:879609. [PMID: 35815212 PMCID: PMC9257189 DOI: 10.3389/fchem.2022.879609] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Accepted: 05/16/2022] [Indexed: 01/17/2023] Open
Abstract
The first member and eponym of the rhodopsin family was identified in the 1930s as the visual pigment of the rod photoreceptor cell in the animal retina. It was found to be a membrane protein, owing its photosensitivity to the presence of a covalently bound chromophoric group. This group, derived from vitamin A, was appropriately dubbed retinal. In the 1970s a microbial counterpart of this species was discovered in an archaeon, being a membrane protein also harbouring retinal as a chromophore, and named bacteriorhodopsin. Since their discovery a photogenic panorama unfolded, where up to date new members and subspecies with a variety of light-driven functionality have been added to this family. The animal branch, meanwhile categorized as type-2 rhodopsins, turned out to form a large subclass in the superfamily of G protein-coupled receptors and are essential to multiple elements of light-dependent animal sensory physiology. The microbial branch, the type-1 rhodopsins, largely function as light-driven ion pumps or channels, but also contain sensory-active and enzyme-sustaining subspecies. In this review we will follow the development of this exciting membrane protein panorama in a representative number of highlights and will present a prospect of their extraordinary future potential.
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Affiliation(s)
- Willem J. de Grip
- Leiden Institute of Chemistry, Department of Biophysical Organic Chemistry, Leiden University, Leiden, Netherlands
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - Srividya Ganapathy
- Department of Imaging Physics, Delft University of Technology, Netherlands
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El‐Tahawy MMT, Conti I, Bonfanti M, Nenov A, Garavelli M. Tailoring Spectral and Photochemical Properties of Bioinspired Retinal Mimics by in Silico Engineering. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202008644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Mohsen M. T. El‐Tahawy
- Dipartimento di Chimica industriale “Toso Montanari” Università di Bologna Viale del Risorigmento 4 40136 Bologna Italy
- Chemistry Department Faculty of Science Damanhour University Damanhour 22511 Egypt
| | - Irene Conti
- Dipartimento di Chimica industriale “Toso Montanari” Università di Bologna Viale del Risorigmento 4 40136 Bologna Italy
| | - Matteo Bonfanti
- Dipartimento di Chimica industriale “Toso Montanari” Università di Bologna Viale del Risorigmento 4 40136 Bologna Italy
| | - Artur Nenov
- Dipartimento di Chimica industriale “Toso Montanari” Università di Bologna Viale del Risorigmento 4 40136 Bologna Italy
| | - Marco Garavelli
- Dipartimento di Chimica industriale “Toso Montanari” Università di Bologna Viale del Risorigmento 4 40136 Bologna Italy
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El‐Tahawy MMT, Conti I, Bonfanti M, Nenov A, Garavelli M. Tailoring Spectral and Photochemical Properties of Bioinspired Retinal Mimics by in Silico Engineering. Angew Chem Int Ed Engl 2020; 59:20619-20627. [DOI: 10.1002/anie.202008644] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Indexed: 11/08/2022]
Affiliation(s)
- Mohsen M. T. El‐Tahawy
- Dipartimento di Chimica industriale “Toso Montanari” Università di Bologna Viale del Risorigmento 4 40136 Bologna Italy
- Chemistry Department Faculty of Science Damanhour University Damanhour 22511 Egypt
| | - Irene Conti
- Dipartimento di Chimica industriale “Toso Montanari” Università di Bologna Viale del Risorigmento 4 40136 Bologna Italy
| | - Matteo Bonfanti
- Dipartimento di Chimica industriale “Toso Montanari” Università di Bologna Viale del Risorigmento 4 40136 Bologna Italy
| | - Artur Nenov
- Dipartimento di Chimica industriale “Toso Montanari” Università di Bologna Viale del Risorigmento 4 40136 Bologna Italy
| | - Marco Garavelli
- Dipartimento di Chimica industriale “Toso Montanari” Università di Bologna Viale del Risorigmento 4 40136 Bologna Italy
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Szefczyk B, Grabarek D, Walczak E, Andruniów T. Excited-state minima and emission energies of retinal chromophore analogues: Performance of CASSCF and CC2 methods as compared with CASPT2. J Comput Chem 2017; 38:1799-1810. [PMID: 28512740 DOI: 10.1002/jcc.24821] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 04/10/2017] [Accepted: 04/13/2017] [Indexed: 11/08/2022]
Abstract
This study provides gas-phase S1 excited-state geometries along with emission and adiabatic energies for methylated/demethylated and ring-locked analogues of protonated Schiff base retinal models comprising system of five conjugated double bonds (PSB5), using second order multiconfiguration perturbation theory (CASPT2). CASPT2 results serve as reference data to assess the performance of CC2 (second-order approximate coupled cluster singles and doubles) and a commonly used CASSCF/CASPT2 protocol, that is, complete active space self-consistent field (CASSCF) geometry optimization followed by CASPT2 energy calculation. We find that the CASSCF methodology fails to locate planar S1 minimum energy structures for four out of five investigated planar models in contrast to CC2 and CASPT2 methods. However, for those which were found: one planar and two twisted minima, there is an excellent agreement between CASSCF and CASPT2 results in terms of geometrical parameters, one-electron properties, as well as emission and adiabatic energies. CC2 performs well for in-plane S1 minima and their spectroscopic and electronic properties. However, this picture deteriorates for twisted minima. As expected, the CC2 description of the S2 electronic state, with strong multireference and significant double excitation character, is very poor, exhibiting errors in transition energies exceeding 1 eV. They may be substantially diminished by recalculating transition energies with CASPT2 method. Our work shows that CASSCF/CASPT2 and CC2 shortcomings may influence gas-phase retinal analogues' excited state description in a dramatic way. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Borys Szefczyk
- Advanced Materials Engineering and Modelling Group, Department of Chemistry, Wroclaw University of Science and Technology, Wyb. Wyspianskiego 27, Wroclaw, 50-370, Poland
| | - Dawid Grabarek
- Advanced Materials Engineering and Modelling Group, Department of Chemistry, Wroclaw University of Science and Technology, Wyb. Wyspianskiego 27, Wroclaw, 50-370, Poland
| | - Elżbieta Walczak
- Advanced Materials Engineering and Modelling Group, Department of Chemistry, Wroclaw University of Science and Technology, Wyb. Wyspianskiego 27, Wroclaw, 50-370, Poland
| | - Tadeusz Andruniów
- Advanced Materials Engineering and Modelling Group, Department of Chemistry, Wroclaw University of Science and Technology, Wyb. Wyspianskiego 27, Wroclaw, 50-370, Poland
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Struts AV, Barmasov AV, Brown MF. CONDENSED-MATTER SPECTROSCOPY SPECTRAL METHODS FOR STUDY OF THE G-PROTEIN-COUPLED RECEPTOR RHODOPSIN. II. MAGNETIC RESONANCE METHODS. OPTICS AND SPECTROSCOPY 2016; 120:286-293. [PMID: 28260816 PMCID: PMC5334789 DOI: 10.1134/s0030400x16010197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
This article continues our review of spectroscopic studies of G-protein-coupled receptors. Magnetic resonance methods including electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) provide specific structural and dynamical data for the protein in conjunction with optical methods (vibrational, electronic spectroscopy) as discussed in the accompanying article. An additional advantage is the opportunity to explore the receptor proteins in the natural membrane lipid environment. Solid-state 2H and 13C NMR methods yield information about the both local structure and dynamics of the cofactor bound to the protein and its light induced changes. Complementary site-directed spin labeling studies monitor the structural alterations over larger distances and correspondingly longer time scales. A multi-scale reaction mechanism describes how local changes of the retinal cofactor unlock the receptor to initiate large-scale conformational changes of rhodopsin. Activation of the G-protein-coupled receptor involves an ensemble of conformational substates within the rhodopsin manifold that characterize the dynamically active receptor.
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Affiliation(s)
- A V Struts
- St. Petersburg State Medical University, 194100 St. Petersburg, Russia; St. Petersburg State University, 199034 St. Petersburg, Russia; University of Arizona, Tucson, AZ 85721 USA
| | - A V Barmasov
- St. Petersburg State Medical University, 194100 St. Petersburg, Russia; St. Petersburg State University, 199034 St. Petersburg, Russia
| | - M F Brown
- St. Petersburg State Medical University, 194100 St. Petersburg, Russia
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Struts AV, Barmasov AV, Brown MF. SPECTRAL METHODS FOR STUDY OF THE G-PROTEIN-COUPLED RECEPTOR RHODOPSIN. I. VIBRATIONAL AND ELECTRONIC SPECTROSCOPY. OPTICS AND SPECTROSCOPY 2015; 118:711-717. [PMID: 28260815 PMCID: PMC5334778 DOI: 10.1134/s0030400x15050240] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Here we review the application of modern spectral methods for the study of G-protein-coupled receptors (GPCRs) using rhodopsin as a prototype. Because X-ray analysis gives us immobile snapshots of protein conformations, it is imperative to apply spectroscopic methods for elucidating their function: vibrational (Raman, FTIR), electronic (UV-visible absorption, fluorescence) spectroscopies, and magnetic resonance (electron paramagnetic resonance, EPR), and nuclear magnetic resonance, NMR). In the first of the two companion articles, we discuss the application of optical spectroscopy for studying rhodopsin in a membrane environment. Information is obtained regarding the time-ordered sequence of events in rhodopsin activation. Isomerization of the chromophore and deprotonation of the retinal Schiff base leads to a structural change of the protein involving the motion of helices H5 and H6 in a pH-dependent process. Information is obtained that is unavailable from X-ray crystallography, which can be combined with spectroscopic studies to achieve a more complete understanding of GPCR function.
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Affiliation(s)
- A V Struts
- St. Petersburg State Medical University, 194100 St. Petersburg, Russia; St. Petersburg State University, 199034 St. Petersburg, Russia; University of Arizona, Tucson, AZ 85721 USA
| | - A V Barmasov
- St. Petersburg State Medical University, 194100 St. Petersburg, Russia; St. Petersburg State University, 199034 St. Petersburg, Russia
| | - M F Brown
- University of Arizona, Tucson, AZ 85721 USA
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Sproviero EM. Opsin Effect on the Electronic Structure of the Retinylidene Chromophore in Rhodopsin. J Chem Theory Comput 2015; 11:1206-19. [PMID: 26579769 DOI: 10.1021/ct500612n] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Direct examination of experimental NMR parameters combined with electronic structure analysis was used to provide a first-principle interpretation of NMR experiments and give a precise evaluation of how the electronic perturbation of the protein environment affects the electronic properties of the retinylidene chromophere in rhodopsin. To this end, we pursued a theoretical analysis using a combination of tools including quantum mechanics/molecular mechanics (QM/MM) at the Density Functional Theory (DFT) level, in conjunction with gauge independent atomic orbital (GIAO) calculations of (13)C NMR chemical shieldings and (1)J(CC) spin-spin coupling constants obtained with the Coupled Perturbed DFT (CPDFT) method. The opsin effect on the retinylidene chromophere is interpreted as an inductive effect of Glu-113 which readjusts the weighting factors of resonance substructures of the conjugated chain of the chromophere. These changes give a rationalization to the alternating effect of the (13)C chemical shifts magnitudes when comparing the retinylidene chromophere in the presence and absence of the protein environment. Conversely, perturbation of π orbitals has little to no effect over (1)J (13)C-(13)C spin-spin coupling constants, as they are mainly dominated by the Fermi contact term, and hence the counteraion effect is restricted to the vicinity of the perturbation. Thus, the apparent contradiction between experimental findings based on chemical shifts (deep penetration) and one-bond J-couplings (localized effects of the protonated Schiff base at the chain terminus) is in fact a consequence of different properties responding differently to the same external perturbation.
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Affiliation(s)
- Eduardo M Sproviero
- Department of Chemistry & Biochemistry, University of the Sciences in Philadelphia , 600 South 43rd Street, Philadelphia, Pennsylvania 19104-4495, United States
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Struts AV, Chawla U, Perera SMDC, Brown MF. Investigation of rhodopsin dynamics in its signaling state by solid-state deuterium NMR spectroscopy. Methods Mol Biol 2015; 1271:133-58. [PMID: 25697522 DOI: 10.1007/978-1-4939-2330-4_10] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Site-directed deuterium NMR spectroscopy is a valuable tool to study the structural dynamics of biomolecules in cases where solution NMR is inapplicable. Solid-state (2)H NMR spectral studies of aligned membrane samples of rhodopsin with selectively labeled retinal provide information on structural changes of the chromophore in different protein states. Moreover (2)H NMR relaxation time measurements allow one to study the dynamics of the ligand during the transition from the inactive to the active state. Here we describe the methodological aspects of solid-state (2)H NMR spectroscopy for functional studies of rhodopsin, with an emphasis on the dynamics of the retinal cofactor. We provide complete protocols for the preparation of NMR samples of rhodopsin with 11-cis-retinal selectively deuterated at the methyl groups in aligned membranes. In addition we review optimized conditions for trapping the rhodopsin photointermediates; and we address the challenging problem of trapping the signaling state of rhodopsin in aligned membrane films.
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Affiliation(s)
- Andrey V Struts
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, USA
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Walczak E, Andruniów T. Impacts of retinal polyene (de)methylation on the photoisomerization mechanism and photon energy storage of rhodopsin. Phys Chem Chem Phys 2015; 17:17169-81. [DOI: 10.1039/c5cp01939g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Similar to native rhodopsin, a two-mode space-saving isomerization mechanism drives the photoreaction in (de)methylated rhodopsin analogues.
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Affiliation(s)
- Elżbieta Walczak
- Department of Chemistry
- Wroclaw University of Technology
- 50-370 Wroclaw
- Poland
| | - Tadeusz Andruniów
- Department of Chemistry
- Wroclaw University of Technology
- 50-370 Wroclaw
- Poland
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Walczak E, Szefczyk B, Andruniów T. Geometries and Vertical Excitation Energies in Retinal Analogues Resolved at the CASPT2 Level of Theory: Critical Assessment of the Performance of CASSCF, CC2, and DFT Methods. J Chem Theory Comput 2013; 9:4915-27. [DOI: 10.1021/ct400423u] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Elżbieta Walczak
- Wroclaw University of Technology, Institute of Physical & Theoretical Chemistry, Wyb. Wyspianskiego 27, 50-370 Wroclaw, Poland
| | - Borys Szefczyk
- Wroclaw University of Technology, Institute of Physical & Theoretical Chemistry, Wyb. Wyspianskiego 27, 50-370 Wroclaw, Poland
| | - Tadeusz Andruniów
- Wroclaw University of Technology, Institute of Physical & Theoretical Chemistry, Wyb. Wyspianskiego 27, 50-370 Wroclaw, Poland
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Pope A, Eilers M, Reeves PJ, Smith SO. Amino acid conservation and interactions in rhodopsin: probing receptor activation by NMR spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1837:683-93. [PMID: 24183693 DOI: 10.1016/j.bbabio.2013.10.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 10/15/2013] [Accepted: 10/18/2013] [Indexed: 11/30/2022]
Abstract
Rhodopsin is a classical two-state G protein-coupled receptor (GPCR). In the dark, its 11-cis retinal chromophore serves as an inverse agonist to lock the receptor in an inactive state. Retinal-protein and protein-protein interactions have evolved to reduce the basal activity of the receptor in order to achieve low dark noise in the visual system. In contrast, absorption of light triggers rapid isomerization of the retinal, which drives the conversion of the receptor to a fully active conformation. Several specific protein-protein interactions have evolved that maintain the lifetime of the active state in order to increase the sensitivity of this receptor for dim-light vision in vertebrates. In this article, we review the molecular interactions that stabilize rhodopsin in the dark-state and describe the use of solid-state NMR spectroscopy for probing the structural changes that occur upon light-activation. Amino acid conservation provides a guide for those interactions that are common in the class A GPCRs as well as those that are unique to the visual system. This article is part of a Special Issue entitled: Retinal Proteins - You can teach an old dog new tricks.
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Affiliation(s)
- Andreyah Pope
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Markus Eilers
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Philip J Reeves
- School of Biological Sciences, University of Essex, Wivenhoe Park, Essex CO4 3SQ, UK
| | - Steven O Smith
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA.
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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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Eilers M, Goncalves JA, Ahuja S, Kirkup C, Hirshfeld A, Simmerling C, Reeves PJ, Sheves M, Smith SO. Structural transitions of transmembrane helix 6 in the formation of metarhodopsin I. J Phys Chem B 2012; 116:10477-89. [PMID: 22564141 DOI: 10.1021/jp3019183] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Absorption of light by the visual pigment rhodopsin triggers a rapid cis-trans photoisomerization of its retinal chromophore and a series of conformational changes in both the retinal and protein. The largest structural change is an outward tilt of transmembrane helix H6 that increases the separation of the intracellular ends of H6 and H3 and opens up the G-protein binding site. In the dark state of rhodopsin, Glu247 at the intracellular end of H6 forms a salt bridge with Arg135 on H3 to tether H6 in an inactive conformation. The Arg135-Glu247 interaction is broken in the active state of the receptor, and Arg135 is then stabilized by interactions with Tyr223, Met257, and Tyr306 on helices H5, H6, and H7, respectively. To address the mechanism of H6 motion, solid-state NMR measurements are undertaken of Metarhodopsin I (Meta I), the intermediate preceding the active Metarhodopsin II (Meta II) state of the receptor. (13)C NMR dipolar recoupling measurements reveal an interhelical contact of (13)Cζ-Arg135 with (13)Cε-Met257 in Meta I but not with (13)Cζ-Tyr223 or (13)Cζ-Tyr306. These observations suggest that helix H6 has rotated in the formation of Meta I but that structural changes involving helices H5 and H7 have not yet occurred. Together, our results provide insights into the sequence of events leading up to the outward motion of H6, a hallmark of G protein-coupled receptor activation.
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Affiliation(s)
- Markus Eilers
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York 11794-5215, United States
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Carlomagno T. NMR in natural products: understanding conformation, configuration and receptor interactions. Nat Prod Rep 2012; 29:536-54. [PMID: 22456471 DOI: 10.1039/c2np00098a] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Covering: up to 2011. Natural products are of tremendous importance in both traditional and modern medicine. For medicinal chemistry natural products represent a challenge, as their chemical synthesis and modification are complex processes, which require many, often stereo-selective, synthetic steps. A prerequisite for the design of analogs of natural products, with more accessible synthetic routes, is the availability of their bioactive conformation. Nuclear Magnetic Resonance (NMR) spectroscopy and X-ray crystallography are the two techniques of choice to investigate the structure of natural products. In this review, I describe the most recent advances in NMR to study the conformation of natural products either free in solution or bound to their cellular receptors. In chapter 2, I focus on the use of residual dipolar couplings (RDC). On the basis of a few examples, I discuss the benefit of complementing classical NMR parameters, such as NOEs and scalar couplings, with dipolar couplings to simultaneously determine both the conformation and the relative configuration of natural products in solution. Chapter 3 is dedicated to the study of the structure of natural products in complex with their cellular receptors and is further divided in two sections. In the first section, I describe two solution-state NMR methodologies to investigate the binding mode of low-affinity ligands to macromolecular receptors. The first approach, INPHARMA (Interligand Noes for PHArmacophore Mapping), is based on the observation of interligand NOEs between two small molecules binding competitively to a common receptor. INPHARMA reveals the relative binding mode of the two ligands, thus allowing ligand superimposition. The second approach is based on paramagnetic relaxation enhancement (PRE) of ligand resonances in the presence of a receptor containing a paramagnetic center. In the second section, I focus on solid-state NMR spectroscopy as a tool to access the bioactive conformation of natural products in complex with macromolecular receptors.
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Affiliation(s)
- Teresa Carlomagno
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, Meyerhofstrasse 1, D-69117 Heidelberg
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15
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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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16
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Sekharan S, Morokuma K. Why 11-cis-retinal? Why not 7-cis-, 9-cis-, or 13-cis-retinal in the eye? J Am Chem Soc 2011; 133:19052-5. [PMID: 22026715 DOI: 10.1021/ja208789h] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
One of the basic and unresolved puzzles in the chemistry of vision concerns the natural selection of 11-cis-retinal as the light-sensing chromophore in visual pigments. A detailed computational examination of the structure, stability, energetics, and spectroscopy of 7-cis-, 9-cis-, 11-cis-, and 13-cis-retinal isomers in vertebrate (bovine, monkey) and invertebrate (squid) visual pigments was carried out using a hybrid quantum mechanics/molecular mechanics (QM/MM) method. The results show that the electrostatic interaction between retinal and opsin dominates the natural selection of 11-cis-retinal over other cis isomers in the dark state. In all of the pigments, 9-cis-retinal was found to be only slightly higher in energy than 11-cis-retinal, which provides strong evidence for the presence of 9-cis-rhodopsin in nature. 7-cis-Retinal is suggested to be an "upside-down" version of the all-trans isomer because the structural rearrangements observed for 7-cis-rhodopsin from squid were found to be very similar to those for squid bathorhodopsin. The progressive red shift in the calculated absorption wavelength (λ(max)) (431, 456, 490, and 508 nm for the 7-cis-, 9-cis-, 11-cis-, and 13-cis-retinal isomers) is due to the decrease in bond length alternation of the retinal.
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Affiliation(s)
- Sivakumar Sekharan
- Cherry L. Emerson Center for Scientific Computation and Department of Chemistry, Emory University, Atlanta, Georgia 30322, USA
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McLean NJ, Gansmuller A, Concistre M, Brown LJ, Levitt MH, Brown RC. Syntheses of 13C2-labelled 11Z-retinals. Tetrahedron 2011. [DOI: 10.1016/j.tet.2011.07.092] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Lu CH, Choi JH, Moran NE, Jin YS, Erdman JW. Laboratory-scale production of 13C-labeled lycopene and phytoene by bioengineered Escherichia coli. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2011; 59:9996-10005. [PMID: 21888370 PMCID: PMC3178727 DOI: 10.1021/jf202599z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Consumption of tomato products has been associated with decreased risks of chronic diseases such as cardiovascular disease and cancer, and therefore the biological functions of tomato carotenoids such as lycopene, phytoene, and phytofluene are being investigated. To study the absorption, distribution, metabolism, and excretion of these carotenoids, a bioengineered Escherichia coli model was evaluated for laboratory-scale production of stable isotope-labeled carotenoids. Carotenoid biosynthetic genes from Enterobacter agglomerans were introduced into the BL21Star(DE3) strain to yield lycopene. Over 96% of accumulated lycopene was in the all-trans form, and the molecules were highly enriched with 13C by 13C-glucose dosing. In addition, error-prone PCR was used to disrupt phytoene desaturase (crtI) function and create a phytoene-accumulating strain, which was also found to maintain the transcription of phytoene synthase (crtB). Phytoene molecules were also highly enriched with 13C when the 13C-glucose was the only carbon source. The development of this production model will provide carotenoid researchers a source of labeled tracer materials to further investigate the metabolism and biological functions of these carotenoids.
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Affiliation(s)
- Chi-Hua Lu
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, 905 S. Goodwin Ave, Urbana, Illinois 61801
| | - Jin-Ho Choi
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, 905 S. Goodwin Ave, Urbana, Illinois 61801
| | - Nancy Engelmann Moran
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, 300 W. 10th Ave., Columbus, Ohio 43210
| | - Yong-Su Jin
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, 905 S. Goodwin Ave, Urbana, Illinois 61801
| | - John W. Erdman
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, 905 S. Goodwin Ave, Urbana, Illinois 61801
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Sekharan S, Morokuma K. QM/MM study of the structure, energy storage, and origin of the bathochromic shift in vertebrate and invertebrate bathorhodopsins. J Am Chem Soc 2011; 133:4734-7. [PMID: 21391708 PMCID: PMC3075117 DOI: 10.1021/ja200322w] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
By comparing the results from a hybrid quantum mechanics/molecular mechanics method (SORCI+Q//B3LYP/6-31G*:Amber) between vertebrate (bovine) and invertebrate (squid) visual pigments, the mechanism of molecular rearrangements, energy storage, and origin of the bathochromic shift accompanying the transformation of rhodopsin to bathorhodopsin have been evaluated. The analysis reveals that, in the presence of an unrelaxed binding site, bathorhodopsin was found to carry almost 27 kcal/mol energy in both visual pigments and absorb (λ(max)) at 528 nm in bovine and 554 nm in squid. However, when the residues within 4.0 Å radius of the retinal are relaxed during the isomerization event, almost ∼16 kcal/mol energy is lost in squid compared to only ∼8 kcal/mol in bovine. Loss of a larger amount of energy in squid is attributed to the presence of a flexible binding site compared to a rigid binding site in bovine. Structure of the squid bathorhodopsin is characterized by formation of a direct H-bond between the Schiff base and Asn87.
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Schapiro I, Ryazantsev MN, Frutos LM, Ferré N, Lindh R, Olivucci M. The Ultrafast Photoisomerizations of Rhodopsin and Bathorhodopsin Are Modulated by Bond Length Alternation and HOOP Driven Electronic Effects. J Am Chem Soc 2011; 133:3354-64. [DOI: 10.1021/ja1056196] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Igor Schapiro
- Chemistry Department, Bowling Green State University, Bowling Green, Ohio 43403, United States
| | | | - Luis Manuel Frutos
- Departamento de Química Física, Universidad de Alcalá, 28871 Alcalá de Henares, Madrid, Spain
| | - Nicolas Ferré
- Laboratoire Chimie Provence UMR 6264, Université de Provence, Campus Saint Jérôme Case 521, 13397 Marseille Cedex 20, France
| | - Roland Lindh
- Department of Quantum Chemistry, Ångströmlab, Lägerhyddsv. 1, Box 518, 751 20 Uppsala University, Sweden
| | - Massimo Olivucci
- Chemistry Department, Bowling Green State University, Bowling Green, Ohio 43403, United States
- Dipartimento di Chimica, Università degli Studi di Siena, via Aldo Moro 2, I-53100 Siena, Italy
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Retinal dynamics underlie its switch from inverse agonist to agonist during rhodopsin activation. Nat Struct Mol Biol 2011; 18:392-4. [PMID: 21278756 DOI: 10.1038/nsmb.1982] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2010] [Accepted: 11/16/2010] [Indexed: 11/08/2022]
Abstract
X-ray and magnetic resonance approaches, though central to studies of G protein-coupled receptor (GPCR)-mediated signaling, cannot address GPCR protein dynamics or plasticity. Here we show that solid-state (2)H NMR relaxation elucidates picosecond-to-nanosecond-timescale motions of the retinal ligand that influence larger-scale functional dynamics of rhodopsin in membranes. We propose a multiscale activation mechanism whereby retinal initiates collective helix fluctuations in the meta I-meta II equilibrium on the microsecond-to-millisecond timescale.
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Goncalves JA, Ahuja S, Erfani S, Eilers M, Smith SO. Structure and function of G protein-coupled receptors using NMR spectroscopy. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2010; 57:159-80. [PMID: 20633362 PMCID: PMC2907352 DOI: 10.1016/j.pnmrs.2010.04.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2010] [Accepted: 04/08/2010] [Indexed: 05/15/2023]
Affiliation(s)
- Joseph A Goncalves
- Department of Biochemistry and Cell Biology, Center for Structural Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
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Dawadi PBS, Lugtenburg J. Synthesis and use of stable isotope enriched retinals in the field of vitamin A. Molecules 2010; 15:1825-72. [PMID: 20336016 PMCID: PMC6257204 DOI: 10.3390/molecules15031825] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Revised: 02/18/2010] [Accepted: 03/02/2010] [Indexed: 01/05/2023] Open
Abstract
The role of vitamin A and its metabolites in the life processes starting with the historical background and its up to date information is discussed in the introduction. Also the role of 11Z-retinal in vision and retinoic acid in the biological processes is elucidated. The essential role of isotopically enriched systems in the progress of vision research, nutrition research etc. is discussed. In part B industrial commercial syntheses of vitamin A by the two leading companies Hoffmann-La Roche (now DSM) and BASF are discussed. The knowledge obtained via these pioneering syntheses has been essential for the further synthetic efforts in vitamin A field by other scientific groups. The rest of the paper is devoted to the synthetic efforts of the Leiden group that gives an access to the preparation of site directed high level isotope enrichment in retinals. First the synthesis of the retinals with deuterium incorporation in the conjugated side chain is reviewed. Then, 13C-labeled retinals are discussed. This is followed by the discussion of a convergent synthetic scheme that allows a rational access to prepare any isotopomer of retinals. The schemes that provide access to prepare any possible isotope enriched chemically modified systems are discussed. Finally, nor-retinals and bridged retinals that give access to a whole (as yet incomplete) library of possible isotopomers are reviewed.
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Affiliation(s)
- Prativa B S Dawadi
- Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA, Leiden, The Netherlands.
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Ahuja S, Eilers M, Hirshfeld A, Yan ECY, Ziliox M, Sakmar TP, Sheves M, Smith SO. 6-s-cis Conformation and polar binding pocket of the retinal chromophore in the photoactivated state of rhodopsin. J Am Chem Soc 2010; 131:15160-9. [PMID: 19795853 DOI: 10.1021/ja9034768] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The visual pigment rhodopsin is unique among the G protein-coupled receptors in having an 11-cis retinal chromophore covalently bound to the protein through a protonated Schiff base linkage. The chromophore locks the visual receptor in an inactive conformation through specific steric and electrostatic interactions. This efficient inverse agonist is rapidly converted to an agonist, the unprotonated Schiff base of all-trans retinal, upon light activation. Here, we use magic angle spinning NMR spectroscopy to obtain the (13)C chemical shifts (C5-C20) of the all-trans retinylidene chromophore and the (15)N chemical shift of the Schiff base nitrogen in the active metarhodopsin II intermediate. The retinal chemical shifts are sensitive to the conformation of the chromophore and its molecular interactions within the protein-binding site. Comparison of the retinal chemical shifts in metarhodopsin II with those of retinal model compounds reveals that the Schiff base environment is polar. In particular, the (13)C15 and (15)Nepsilon chemical shifts indicate that the C horizontal lineN bond is highly polarized in a manner that would facilitate Schiff base hydrolysis. We show that a strong perturbation of the retinal (13)C12 chemical shift observed in rhodopsin is reduced in wild-type metarhodopsin II and in the E181Q mutant of rhodopsin. On the basis of the T(1) relaxation time of the retinal (13)C18 methyl group and the conjugated retinal (13)C5 and (13)C8 chemical shifts, we have determined that the conformation of the retinal C6-C7 single bond connecting the beta-ionone ring and the retinylidene chain is 6-s-cis in both the inactive and the active states of rhodopsin. These results are discussed within the general framework of ligand-activated G protein-coupled receptors.
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Affiliation(s)
- Shivani Ahuja
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-5215, USA
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Bovee-Geurts PHM, Fernández Fernández I, Liu RSH, Mathies RA, Lugtenburg J, DeGrip WJ. Fluoro Derivatives of Retinal Illuminate the Decisive Role of the C12-H Element in Photoisomerization and Rhodopsin Activation. J Am Chem Soc 2009; 131:17933-42. [DOI: 10.1021/ja907577p] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Petra H. M. Bovee-Geurts
- Department of Biochemistry, UMCN 286, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands, Department of BioOrganic Photochemistry, Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands, Department of Chemistry, University of Hawaii at Manao, 2545 The Mall, Honolulu, Hawaii 96822, and Department of Chemistry, University of California, Berkeley, California 94720
| | - Isabelle Fernández Fernández
- Department of Biochemistry, UMCN 286, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands, Department of BioOrganic Photochemistry, Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands, Department of Chemistry, University of Hawaii at Manao, 2545 The Mall, Honolulu, Hawaii 96822, and Department of Chemistry, University of California, Berkeley, California 94720
| | - Robert S. H. Liu
- Department of Biochemistry, UMCN 286, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands, Department of BioOrganic Photochemistry, Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands, Department of Chemistry, University of Hawaii at Manao, 2545 The Mall, Honolulu, Hawaii 96822, and Department of Chemistry, University of California, Berkeley, California 94720
| | - Richard A. Mathies
- Department of Biochemistry, UMCN 286, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands, Department of BioOrganic Photochemistry, Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands, Department of Chemistry, University of Hawaii at Manao, 2545 The Mall, Honolulu, Hawaii 96822, and Department of Chemistry, University of California, Berkeley, California 94720
| | - Johan Lugtenburg
- Department of Biochemistry, UMCN 286, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands, Department of BioOrganic Photochemistry, Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands, Department of Chemistry, University of Hawaii at Manao, 2545 The Mall, Honolulu, Hawaii 96822, and Department of Chemistry, University of California, Berkeley, California 94720
| | - Willem J. DeGrip
- Department of Biochemistry, UMCN 286, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands, Department of BioOrganic Photochemistry, Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands, Department of Chemistry, University of Hawaii at Manao, 2545 The Mall, Honolulu, Hawaii 96822, and Department of Chemistry, University of California, Berkeley, California 94720
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Brown MF, Salgado GFJ, Struts AV. Retinal dynamics during light activation of rhodopsin revealed by solid-state NMR spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1798:177-93. [PMID: 19716801 DOI: 10.1016/j.bbamem.2009.08.013] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2009] [Revised: 07/25/2009] [Accepted: 08/12/2009] [Indexed: 11/28/2022]
Abstract
Rhodopsin is a canonical member of class A of the G protein-coupled receptors (GPCRs) that are implicated in many of the drug interventions in humans and are of great pharmaceutical interest. The molecular mechanism of rhodopsin activation remains unknown as atomistic structural information for the active metarhodopsin II state is currently lacking. Solid-state (2)H NMR constitutes a powerful approach to study atomic-level dynamics of membrane proteins. In the present application, we describe how information is obtained about interactions of the retinal cofactor with rhodopsin that change with light activation of the photoreceptor. The retinal methyl groups play an important role in rhodopsin function by directing conformational changes upon transition into the active state. Site-specific (2)H labels have been introduced into the methyl groups of retinal and solid-state (2)H NMR methods applied to obtain order parameters and correlation times that quantify the mobility of the cofactor in the inactive dark state, as well as the cryotrapped metarhodopsin I and metarhodopsin II states. Analysis of the angular-dependent (2)H NMR line shapes for selectively deuterated methyl groups of rhodopsin in aligned membranes enables determination of the average ligand conformation within the binding pocket. The relaxation data suggest that the beta-ionone ring is not expelled from its hydrophobic pocket in the transition from the pre-activated metarhodopsin I to the active metarhodopsin II state. Rather, the major structural changes of the retinal cofactor occur already at the metarhodopsin I state in the activation process. The metarhodopsin I to metarhodopsin II transition involves mainly conformational changes of the protein within the membrane lipid bilayer rather than the ligand. The dynamics of the retinylidene methyl groups upon isomerization are explained by an activation mechanism involving cooperative rearrangements of extracellular loop E2 together with transmembrane helices H5 and H6. These activating movements are triggered by steric clashes of the isomerized all-trans retinal with the beta4 strand of the E2 loop and the side chains of Glu(122) and Trp(265) within the binding pocket. The solid-state (2)H NMR data are discussed with regard to the pathway of the energy flow in the receptor activation mechanism.
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Affiliation(s)
- Michael F Brown
- Department of Chemistry, University of Arizona, Tucson, AZ 85721, USA; Department of Physics, University of Arizona, Tucson, AZ 85721, USA.
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Feldman TB, Kholmurodov KT, Ostrovsky MA, Khrenova MG, Nemukhin AV. Studies on the conformational state of the chromophore group (11-cis-retinal) in rhodopsin by computer molecular simulation methods. Biophysics (Nagoya-shi) 2009. [DOI: 10.1134/s0006350909040113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Brown MF, Martínez-Mayorga K, Nakanishi K, Salgado GFJ, Struts AV. Retinal conformation and dynamics in activation of rhodopsin illuminated by solid-state H NMR spectroscopy. Photochem Photobiol 2009; 85:442-53. [PMID: 19267870 DOI: 10.1111/j.1751-1097.2008.00510.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Solid-state NMR spectroscopy gives a powerful avenue for investigating G protein-coupled receptors and other integral membrane proteins in a native-like environment. This article reviews the use of solid-state (2)H NMR to study the retinal cofactor of rhodopsin in the dark state as well as the meta I and meta II photointermediates. Site-specific (2)H NMR labels have been introduced into three regions (methyl groups) of retinal that are crucially important for the photochemical function of rhodopsin. Despite its phenomenal stability (2)H NMR spectroscopy indicates retinal undergoes rapid fluctuations within the protein binding cavity. The spectral lineshapes reveal the methyl groups spin rapidly about their three-fold (C(3)) axes with an order parameter for the off-axial motion of SC(3) approximately 0.9. For the dark state, the (2)H NMR structure of 11-cis-retinal manifests torsional twisting of both the polyene chain and the beta-ionone ring due to steric interactions of the ligand and the protein. Retinal is accommodated within the rhodopsin binding pocket with a negative pretwist about the C11=C12 double bond. Conformational distortion explains its rapid photochemistry and reveals the trajectory of the 11-cis to trans isomerization. In addition, (2)H NMR has been applied to study the retinylidene dynamics in the dark and light-activated states. Upon isomerization there are drastic changes in the mobility of all three methyl groups. The relaxation data support an activation mechanism whereby the beta-ionone ring of retinal stays in nearly the same environment, without a large displacement of the ligand. Interactions of the beta-ionone ring and the retinylidene Schiff base with the protein transmit the force of the retinal isomerization. Solid-state (2)H NMR thus provides information about the flow of energy that triggers changes in hydrogen-bonding networks and helix movements in the activation mechanism of the photoreceptor.
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Affiliation(s)
- Michael F Brown
- Department of Chemistry, University of Arizona, Tucson, AZ, USA.
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Concistrè M, Gansmüller A, McLean N, Johannessen OG, Marín Montesinos I, Bovee-Geurts PHM, Brown RCD, DeGrip WJ, Levitt MH. Light penetration and photoisomerization in rhodopsin studied by numerical simulations and double-quantum solid-state NMR spectroscopy. J Am Chem Soc 2009; 131:6133-40. [PMID: 19354207 DOI: 10.1021/ja809878c] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The penetration of light into optically thick samples containing the G-protein-coupled receptor rhodopsin is studied by numerical finite-element simulations and double-quantum solid-state NMR experiments. Illumination with white light leads to the generation of the active bathorhodopsin photostate in the outer layer of the sample but generates a large amount of the side product, isorhodopsin, in the sample interior. The overall yield of bathorhodopsin is improved by using monochromatic 420 nm illumination and by mixing the sample with transparent glass beads. The implications of these findings on the interpretation of previously published rhodopsin NMR data are discussed.
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Gansmüller A, Concistrè M, McLean N, Johannessen OG, Marín-Montesinos I, Bovee-Geurts PHM, Verdegem P, Lugtenburg J, Brown RCD, Degrip WJ, Levitt MH. Towards an interpretation of 13C chemical shifts in bathorhodopsin, a functional intermediate of a G-protein coupled receptor. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:1350-7. [PMID: 19265671 DOI: 10.1016/j.bbamem.2009.02.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Revised: 02/13/2009] [Accepted: 02/18/2009] [Indexed: 10/21/2022]
Abstract
Photoisomerization of the membrane-bound light receptor protein rhodopsin leads to an energy-rich photostate called bathorhodopsin, which may be trapped at temperatures of 120 K or lower. We recently studied bathorhodopsin by low-temperature solid-state NMR, using in situ illumination of the sample in a purpose-built NMR probe. In this way we acquired (13)C chemical shifts along the retinylidene chain of the chromophore. Here we compare these results with the chemical shifts of the dark state chromophore in rhodopsin, as well as with the chemical shifts of retinylidene model compounds in solution. An earlier solid-state NMR study of bathorhodopsin found only small changes in the (13)C chemical shifts upon isomerization, suggesting only minor perturbations of the electronic structure in the isomerized retinylidene chain. This is at variance with our recent measurements which show much larger perturbations of the (13)C chemical shifts. Here we present a tentative interpretation of our NMR results involving an increased charge delocalization inside the polyene chain of the bathorhodopsin chromophore. Our results suggest that the bathochromic shift of bathorhodopsin is due to modified electrostatic interactions between the chromophore and the binding pocket, whereas both electrostatic interactions and torsional strain are involved in the energy storage mechanism of bathorhodopsin.
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Affiliation(s)
- Axel Gansmüller
- School of Chemistry, University of Southampton, SO17 1BJ Southampton, England, UK
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Brown MF, Heyn MP, Job C, Kim S, Moltke S, Nakanishi K, Nevzorov AA, Struts AV, Salgado GFJ, Wallat I. Solid-state 2H NMR spectroscopy of retinal proteins in aligned membranes. BIOCHIMICA ET BIOPHYSICA ACTA 2007; 1768:2979-3000. [PMID: 18021739 PMCID: PMC5233718 DOI: 10.1016/j.bbamem.2007.10.014] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2007] [Revised: 10/10/2007] [Accepted: 10/10/2007] [Indexed: 11/21/2022]
Abstract
Solid-state 2H NMR spectroscopy gives a powerful avenue to investigating the structures of ligands and cofactors bound to integral membrane proteins. For bacteriorhodopsin (bR) and rhodopsin, retinal was site-specifically labeled by deuteration of the methyl groups followed by regeneration of the apoprotein. 2H NMR studies of aligned membrane samples were conducted under conditions where rotational and translational diffusion of the protein were absent on the NMR time scale. The theoretical lineshape treatment involved a static axial distribution of rotating C-C2H3 groups about the local membrane frame, together with the static axial distribution of the local normal relative to the average normal. Simulation of solid-state 2H NMR lineshapes gave both the methyl group orientations and the alignment disorder (mosaic spread) of the membrane stack. The methyl bond orientations provided the angular restraints for structural analysis. In the case of bR the retinal chromophore is nearly planar in the dark- and all-trans light-adapted states, as well upon isomerization to 13-cis in the M state. The C13-methyl group at the "business end" of the chromophore changes its orientation to the membrane upon photon absorption, moving towards W182 and thus driving the proton pump in energy conservation. Moreover, rhodopsin was studied as a prototype for G protein-coupled receptors (GPCRs) implicated in many biological responses in humans. In contrast to bR, the retinal chromophore of rhodopsin has an 11-cis conformation and is highly twisted in the dark state. Three sites of interaction affect the torsional deformation of retinal, viz. the protonated Schiff base with its carboxylate counterion; the C9-methyl group of the polyene; and the beta-ionone ring within its hydrophobic pocket. For rhodopsin, the strain energy and dynamics of retinal as established by 2H NMR are implicated in substituent control of activation. Retinal is locked in a conformation that is twisted in the direction of the photoisomerization, which explains the dark stability of rhodopsin and allows for ultra-fast isomerization upon absorption of a photon. Torsional strain is relaxed in the meta I state that precedes subsequent receptor activation. Comparison of the two retinal proteins using solid-state 2H NMR is thus illuminating in terms of their different biological functions.
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Affiliation(s)
- Michael F Brown
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721, USA.
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Tanaka K, Struts AV, Krane S, Fujioka N, Salgado GFJ, Martínez-Mayorga K, Brown MF, Nakanishi K. Synthesis of CD3-Labeled 11-cis-Retinals and Application to Solid-State Deuterium NMR Spectroscopy of Rhodopsin. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2007. [DOI: 10.1246/bcsj.80.2177] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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The conformation of acetylcholine at its target site in the membrane-embedded nicotinic acetylcholine receptor. Proc Natl Acad Sci U S A 2007; 104:18031-6. [PMID: 17989232 DOI: 10.1073/pnas.0704785104] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The conformation of the neurotransmitter acetylcholine bound to the fully functional nicotinic acetylcholine receptor embedded in its native membrane environment has been characterized by using frequency-selective recoupling solid-state NMR. Six dipolar couplings among five resolved (13)C-labeled atoms of acetylcholine were measured. Bound acetylcholine adopts a bent conformation characterized with a quaternary ammonium-to-carbonyl distance of 5.1 A. In this conformation, and with its orientation constrained to that previously determined by us, the acetylcholine could be docked satisfactorily in the agonist pocket of the agonist-bound, but not the agonist-free, crystal structure of a soluble acetylcholine-binding protein from Lymnaea stagnali. The quaternary ammonium group of the acetylcholine was determined to be within 3.9 A of five aromatic residues and its acetyl group close to residues C187/188 of the principle and residue L112 of the complementary subunit. The observed >C O chemical shift is consistent with H bonding to the nicotinic acetylcholine receptor residues gammaY116 and deltaT119 that are homologous to L112 in the soluble acetylcholine-binding protein.
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Frutos LM, Andruniów T, Santoro F, Ferré N, Olivucci M. Tracking the excited-state time evolution of the visual pigment with multiconfigurational quantum chemistry. Proc Natl Acad Sci U S A 2007; 104:7764-9. [PMID: 17470789 PMCID: PMC1876521 DOI: 10.1073/pnas.0701732104] [Citation(s) in RCA: 221] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2007] [Indexed: 11/18/2022] Open
Abstract
The primary event that initiates vision is the photoinduced isomerization of retinal in the visual pigment rhodopsin (Rh). Here, we use a scaled quantum mechanics/molecular mechanics potential that reproduces the isomerization path determined with multiconfigurational perturbation theory to follow the excited-state evolution of bovine Rh. The analysis of a 140-fs trajectory provides a description of the electronic and geometrical changes that prepare the system for decay to the ground state. The data uncover a complex change of the retinal backbone that, at approximately 60-fs delay, initiates a space saving "asynchronous bicycle-pedal or crankshaft" motion, leading to a conical intersection on a 110-fs time scale. It is shown that the twisted structure achieved at decay features a momentum that provides a natural route toward the photoRh structure recently resolved by using femtosecond-stimulated Raman spectroscopy.
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Affiliation(s)
- Luis Manuel Frutos
- Dipartimento di Chimica, Università di Siena, via Aldo Moro 2, I-53100 Siena, Italy
| | - Tadeusz Andruniów
- Institute of Physical and Theoretical Chemistry, Department of Chemistry, Wroclaw University of Technology, 27 Wyb. Wyspianskiego, 50-370, Wroclaw, Poland
| | - Fabrizio Santoro
- Istituto per i Processi Chimico-Fisici, Consiglio Nazionale delle Ricerche, Via Moruzzi 1, I-56124 Pisa, Italy; and
| | - Nicolas Ferré
- Laboratoire de Chimie Théorique et de Modélisation Moléculaire, Unité Mixte de Recherche 6517, Centre National de la Recherche Scientifique, Université de Provence, Case 521, Faculté de Saint-Jérôme, Avenue Esc. Normandie Niemen, 13397 Marseille Cedex 20, France
| | - Massimo Olivucci
- Dipartimento di Chimica, Università di Siena, via Aldo Moro 2, I-53100 Siena, Italy
- Department of Chemistry, Bowling Green State University, Bowling Green, OH 43403
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Werner K, Lehner I, Dhiman HK, Richter C, Glaubitz C, Schwalbe H, Klein-Seetharaman J, Khorana HG. Combined solid state and solution NMR studies of alpha,epsilon-15N labeled bovine rhodopsin. JOURNAL OF BIOMOLECULAR NMR 2007; 37:303-12. [PMID: 17318366 DOI: 10.1007/s10858-007-9143-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2007] [Accepted: 01/08/2007] [Indexed: 05/14/2023]
Abstract
Rhodopsin is the visual pigment of the vertebrate rod photoreceptor cell and is the only member of the G protein coupled receptor family for which a crystal structure is available. Towards the study of dynamics in rhodopsin, we report NMR-spectroscopic investigations of alpha,epsilon-15N-tryptophan labeled rhodopsin in detergent micelles and reconstituted in phospholipids. Using a combination of solid state 13C,15N-REDOR and HETCOR experiments of all possible 13C'(i-1) carbonyl/15N(i)-tryptophan isotope labeled amide pairs, and H/D exchange 1H,15N-HSQC experiments conducted in solution, we assigned chemical shifts to all five rhodopsin tryptophan backbone 15N nuclei and partially to their bound protons. 1H,15N chemical shift assignment was achieved for indole side chains of Trp35(1.30) and Trp175(4.65). 15N chemical shifts were found to be similar when comparing those obtained in the native like reconstituted lipid environment and those obtained in detergent micelles for all tryptophans except Trp175(4.65) at the membrane interface. The results suggest that the integrated solution and solid state NMR approach presented provides highly complementary information in the study of structure and dynamics of large membrane proteins like rhodopsin.
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Affiliation(s)
- Karla Werner
- Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-Universität Frankfurt, Max-von-Laue-Str. 7, 60438 Frankfurt/Main, Germany
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Struts AV, Salgado GFJ, Tanaka K, Krane S, Nakanishi K, Brown MF. Structural analysis and dynamics of retinal chromophore in dark and meta I states of rhodopsin from 2H NMR of aligned membranes. J Mol Biol 2007; 372:50-66. [PMID: 17640664 PMCID: PMC5233725 DOI: 10.1016/j.jmb.2007.03.046] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2006] [Revised: 03/02/2007] [Accepted: 03/19/2007] [Indexed: 11/29/2022]
Abstract
Rhodopsin is a prototype for G protein-coupled receptors (GPCRs) that are implicated in many biological responses in humans. A site-directed (2)H NMR approach was used for structural analysis of retinal within its binding cavity in the dark and pre-activated meta I states. Retinal was labeled with (2)H at the C5, C9, or C13 methyl groups by total synthesis, and was used to regenerate the opsin apoprotein. Solid-state (2)H NMR spectra were acquired for aligned membranes in the low-temperature lipid gel phase versus the tilt angle to the magnetic field. Data reduction assumed a static uniaxial distribution, and gave the retinylidene methyl bond orientations plus the alignment disorder (mosaic spread). The dark-state (2)H NMR structure of 11-cis-retinal shows torsional twisting of the polyene chain and the beta-ionone ring. The ligand undergoes restricted motion, as evinced by order parameters of approximately 0.9 for the spinning C-C(2)H(3) groups, with off-axial fluctuations of approximately 15 degrees . Retinal is accommodated within the rhodopsin binding pocket with a negative pre-twist about the C11=C12 double bond that explains its rapid photochemistry and the trajectory of 11-cis to trans isomerization. In the cryo-trapped meta I state, the (2)H NMR structure shows a reduction of the polyene strain, while torsional twisting of the beta-ionone ring is maintained. Distortion of the retinal conformation is interpreted through substituent control of receptor activation. Steric hindrance between trans retinal and Trp265 can trigger formation of the subsequent activated meta II state. Our results are pertinent to quantum and molecular mechanics simulations of ligands bound to GPCRs, and illustrate how (2)H NMR can be applied to study their biological mechanisms of action.
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Affiliation(s)
- Andrey V. Struts
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721, USA
| | - Gilmar F. J. Salgado
- Department of Biochemistry & Molecular Biophysics, University of Arizona, Tucson, Arizona 85721, USA
| | - Katsunori Tanaka
- Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - Sonja Krane
- Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - Koji Nakanishi
- Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - Michael F. Brown
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721, USA
- Department of Biochemistry & Molecular Biophysics, University of Arizona, Tucson, Arizona 85721, USA
- Department of Physics, University of Arizona, Tucson, Arizona 85721, USA
- Corresponding author:
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38
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Coto PB, Strambi A, Ferré N, Olivucci M. The color of rhodopsins at the ab initio multiconfigurational perturbation theory resolution. Proc Natl Acad Sci U S A 2006; 103:17154-9. [PMID: 17090682 PMCID: PMC1859901 DOI: 10.1073/pnas.0604048103] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2006] [Indexed: 11/18/2022] Open
Abstract
We demonstrate that "brute force" quantum-mechanics/molecular-mechanics computations based on ab initio (i.e., first principles) multiconfigurational perturbation theory can reproduce the absorption maxima of a set of modified bovine rhodopsins with an accuracy allowing for the analysis of the factors determining their colors. In particular, we show that the theory accounts for the changes in excitation energy even when the proteins display the same charge distribution. Three color-tuning mechanisms, leading to changes of close magnitude, are demonstrated to operate in these conditions. The first is based on the change of the conformation of the conjugated backbone of the retinal chromophore. The second operates through the control of the distance between the positive charge residing on the chromophore and the carboxylate counterion. Finally, the third mechanism operates through the changes in orientation of the chromophore relative to the protein. These results offer perspectives for the unbiased computational design of mutants or chemically modified proteins with wanted optical properties.
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Affiliation(s)
- Pedro B. Coto
- Dipartimento di Chimica, Università di Siena, via Aldo Moro 2, I-53100 Siena, Italy
| | - Angela Strambi
- Dipartimento di Chimica, Università di Siena, via Aldo Moro 2, I-53100 Siena, Italy
| | - Nicolas Ferré
- Laboratoire de Chimie Théorique et de Modélisation Moléculaire, Unite Mixte de Recherche 6517, Centre National de la Recherche Scientifique, Université de Provence, Case 521 Faculté de Saint-Jérôme, Avenue Esc. Normandie Niemen, 13397 Marseille Cedex 20, France; and
| | - Massimo Olivucci
- Dipartimento di Chimica, Università di Siena, via Aldo Moro 2, I-53100 Siena, Italy
- Chemistry Department, Bowling Green State University, Bowling Green, OH 43403
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Verhoeven MA, Bovee-Geurts PHM, de Groot HJM, Lugtenburg J, DeGrip WJ. Methyl Substituents at the 11 or 12 Position of Retinal Profoundly and Differentially Affect Photochemistry and Signalling Activity of Rhodopsin. J Mol Biol 2006; 363:98-113. [PMID: 16962138 DOI: 10.1016/j.jmb.2006.07.039] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2006] [Revised: 07/12/2006] [Accepted: 07/19/2006] [Indexed: 11/18/2022]
Abstract
The C-11=C-12 double bond of the retinylidene chromophore of rhodopsin holds a central position in its light-induced photoisomerization and hence the photosensory function of this visual pigment. To probe the local environment of the HC-11=C-12H element we have prepared the 11-methyl and 12-methyl derivatives of 11-Z retinal and incorporated these into opsin to generate the rhodopsin analogs 11-methyl and 12-methyl rhodopsin. These analog pigments form with much slower kinetics and lower efficiency than the native pigment. The initial photochemistry and the signaling activity of the analog pigments were investigated by UV-vis and FTIR spectroscopy, and by a G protein activation assay. Our data indicate that the ultrafast formation of the first photointermediate is strongly perturbed by the presence of an 11-methyl substituent, but much less by a 12-methyl substituent. These results support the current concept of the mechanism of the primary photoisomerization event in rhodopsin. An important stronghold of this concept is an out-of-plane movement of the C-12H element, which is facilitated by torsion as well as extended positive charge delocalization into the C-10-C-13 segment of the chromophore. We argue that this mechanism is maintained principally with a methyl substituent at C-12. In addition, we show that both an 11-methyl and a 12-methyl substitutent perturb the photointermediate cascade and finally yield a low-activity state of the receptor. The 11-methyl pigment retains about 30% of the G protein activation rate of native rhodopsin, while the 12-methyl chromophore behaves like an inverse agonist up to at least 20 degrees C, trapping the protein in a perturbed Meta-I-like conformation. We conclude that the isomerization region of the chromophore and the spatial structure of the binding site are finely tuned, in order to achieve a high photosensory potential with an efficient pathway to a high-activity state.
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40
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Kholmurodov KT, Feldman TB, Ostrovsky MA. Visual pigment rhodopsin : a computer simulation of the molecular dynamics of 11-cis-retinal chromophore and amino-acid residues in the chromophore centre. MENDELEEV COMMUNICATIONS 2006. [DOI: 10.1070/mc2006v016n01abeh002255] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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41
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Andruniów T, Ferré N, Olivucci M. Structure, initial excited-state relaxation, and energy storage of rhodopsin resolved at the multiconfigurational perturbation theory level. Proc Natl Acad Sci U S A 2004; 101:17908-13. [PMID: 15604139 PMCID: PMC539762 DOI: 10.1073/pnas.0407997101] [Citation(s) in RCA: 186] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We demonstrate that a "brute force" quantum chemical calculation based on an ab initio multiconfigurational second order perturbation theory approach implemented in a quantum mechanics/molecular mechanics strategy can be applied to the investigation of the excited state of the visual pigment rhodopsin (Rh) with a computational error <5 kcal.mol(-1). As a consequence, the simulation of the absorption and fluorescence of Rh and its retinal chromophore in solution allows for a nearly quantitative analysis of the factors determining the properties of the protein environment. More specifically, we demonstrate that the Rh environment is more similar to the "gas phase" than to the solution environment and that the so-called "opsin shift" originates from the inability of the solvent to effectively "shield" the chromophore from its counterion. The same strategy is used to investigate three transient structures involved in the photoisomerization of Rh under the assumption that the protein cavity does not change shape during the reaction. Accordingly, the analysis of the initially relaxed excited-state structure, the conical intersection driving the excited-state decay, and the primary isolable bathorhodopsin intermediate supports a mechanism where the photoisomerization coordinate involves a "motion" reminiscent of the so-called bicycle-pedal reaction coordinate. Most importantly, it is shown that the mechanism of the approximately 30 kcal.mol(-1) photon energy storage observed for Rh is not consistent with a model based exclusively on the change of the electrostatic interaction of the chromophore with the protein/counterion environment.
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Affiliation(s)
- Tadeusz Andruniów
- Dipartimento di Chimica, Università di Siena, Via Aldo Moro I-53100 Siena, Italy
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42
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Wang Y, Lugtenburg J. Preparation of (all-E)- and (11Z)-12-Haloretinals and (11Z,13Z)- and (13Z)-14-Haloretinals by the C15 + C5 Route ? Exploring the Possibility of Preparing any Retinoid Rationally Chemically Modified at any Position in the Conjugated Tail. European J Org Chem 2004. [DOI: 10.1002/ejoc.200400488] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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43
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Okada T, Sugihara M, Bondar AN, Elstner M, Entel P, Buss V. The retinal conformation and its environment in rhodopsin in light of a new 2.2 A crystal structure. J Mol Biol 2004; 342:571-83. [PMID: 15327956 DOI: 10.1016/j.jmb.2004.07.044] [Citation(s) in RCA: 847] [Impact Index Per Article: 42.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2004] [Revised: 07/07/2004] [Accepted: 07/12/2004] [Indexed: 11/27/2022]
Abstract
A new high-resolution structure is reported for bovine rhodopsin, the visual pigment in rod photoreceptor cells. Substantial improvement of the resolution limit to 2.2 A has been achieved by new crystallization conditions, which also reduce significantly the probability of merohedral twinning in the crystals. The new structure completely resolves the polypeptide chain and provides further details of the chromophore binding site including the configuration about the C6-C7 single bond of the 11-cis-retinal Schiff base. Based on both an earlier structure and the new improved model of the protein, a theoretical study of the chromophore geometry has been carried out using combined quantum mechanics/force field molecular dynamics. The consistency between the experimental and calculated chromophore structures is found to be significantly improved for the 2.2 A model, including the angle of the negatively twisted 6-s-cis-bond. Importantly, the new crystal structure refinement reveals significant negative pre-twist of the C11-C12 double bond and this is also supported by the theoretical calculation although the latter converges to a smaller value. Bond alternation along the unsaturated chain is significant, but weaker in the calculated structure than the one obtained from the X-ray data. Other differences between the experimental and theoretical structures in the chromophore binding site are discussed with respect to the unique spectral properties and excited state reactivity of the chromophore.
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Affiliation(s)
- Tetsuji Okada
- Biological Information Research Center, National Institute of Advanced Industrial Science and Technology, 2-41-6 Aomi, Koto-ku, Tokyo 135-0064, Japan.
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44
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Sakmar TP, Menon ST, Marin EP, Awad ES. Rhodopsin: insights from recent structural studies. ANNUAL REVIEW OF BIOPHYSICS AND BIOMOLECULAR STRUCTURE 2002; 31:443-84. [PMID: 11988478 DOI: 10.1146/annurev.biophys.31.082901.134348] [Citation(s) in RCA: 189] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The recent report of the crystal structure of rhodopsin provides insights concerning structure-activity relationships in visual pigments and related G protein-coupled receptors (GPCRs). The seven transmembrane helices of rhodopsin are interrupted or kinked at multiple sites. An extensive network of interhelical interactions stabilizes the ground state of the receptor. The ligand-binding pocket of rhodopsin is remarkably compact, and several chromophore-protein interactions were not predicted from mutagenesis or spectroscopic studies. The helix movement model of receptor activation, which likely applies to all GPCRs of the rhodopsin family, is supported by several structural elements that suggest how light-induced conformational changes in the ligand-binding pocket are transmitted to the cytoplasmic surface. The cytoplasmic domain of the receptor includes a helical domain extending from the seventh transmembrane segment parallel to the bilayer surface. The cytoplasmic surface appears to be approximately large enough to bind to the transducin heterotrimer in a one-to-one complex. The structural basis for several unique biophysical properties of rhodopsin, including its extremely low dark noise level and high quantum efficiency, can now be addressed using a combination of structural biology and various spectroscopic methods. Future high-resolution structural studies of rhodopsin and other GPCRs will form the basis to elucidate the detailed molecular mechanism of GPCR-mediated signal transduction.
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Affiliation(s)
- Thomas P Sakmar
- Howard Hughes Medical Institute, Laboratory of Molecular Biology and Biochemistry, The Rockefeller University, New York, NY 10021, USA.
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45
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Creemers AFL, Kiihne S, Bovee-Geurts PHM, DeGrip WJ, Lugtenburg J, de Groot HJM. (1)H and (13)C MAS NMR evidence for pronounced ligand-protein interactions involving the ionone ring of the retinylidene chromophore in rhodopsin. Proc Natl Acad Sci U S A 2002; 99:9101-6. [PMID: 12093898 PMCID: PMC123100 DOI: 10.1073/pnas.112677599] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2001] [Indexed: 11/18/2022] Open
Abstract
Rhodopsin is a member of the superfamily of G-protein-coupled receptors. This seven alpha-helix transmembrane protein is the visual pigment of the vertebrate rod photoreceptor cells that mediate dim light vision. In the active binding site of this protein the ligand or chromophore, 11-cis-retinal, is covalently bound via a protonated Schiff base to lysine residue 296. Here we present the complete (1)H and (13)C assignments of the 11-cis-retinylidene chromophore in its ligand-binding site determined with ultra high field magic angle spinning NMR. Native bovine opsin was regenerated with 99% enriched uniformly (13)C-labeled 11-cis-retinal. From the labeled pigment, (13)C carbon chemical shifts could be obtained by using two-dimensional radio frequency-driven dipolar recoupling in a solid-state magic angle spinning homonuclear correlation experiment. The (1)H chemical shifts were assigned by two-dimensional heteronuclear ((1)H-(13)C) dipolar correlation spectroscopy with phase-modulated Lee-Goldburg homonuclear (1)H decoupling applied during the t(1) period. The data indicate nonbonding interactions between the protons of the methyl groups of the retinylidene ionone ring and the protein. These nonbonding interactions are attributed to nearby aromatic acid residues Phe-208, Phe-212, and Trp-265 that are in close contact with, respectively, H-16/H-17 and H-18. Furthermore, binding of the chromophore involves a chiral selection of the ring conformation, resulting in equatorial and axial positions for CH(3)-16 and CH(3)-17.
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Affiliation(s)
- Alain F L Creemers
- Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA, Leiden, The Netherlands
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46
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Fujimoto Y, Fishkin N, Pescitelli G, Decatur J, Berova N, Nakanishi K. Solution and biologically relevant conformations of enantiomeric 11-cis-locked cyclopropyl retinals. J Am Chem Soc 2002; 124:7294-302. [PMID: 12071738 DOI: 10.1021/ja020083e] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
To gain information on the conformation of the 11-cis-retinylidene chromophore bound to bovine opsin, the enantiomeric pair (2a and 2b) of 11-cis-locked bicyclo[5.1.0]octyl retinal (retCPr) 2 was prepared and its conformation was investigated by NMR, geometry optimization, and CD calculations. This compound is also of interest since it contains a unique moiety in which a chiral cyclopropyl group is flanked by triene and enal chromophores, and hence would clarify the little-known chiroptical contribution of a cyclopropyl ring linked to polyene systems. NMR revealed that the seven-membered ring of retCPr adopts a twist chair conformation. The NMR-derived structure constraints were then used for optimizing the geometry of 2 with molecular mechanics and ab initio methods. This revealed that enantiomer 2a with a 11 beta,12 beta-cyclopropyl group exists as two populations of diastereomers depending on the twist around the 6-s bond; however, the sense of twist around the 12-s is positive in both rotamers. The theoretical Boltzmann-weighted CD obtained with the pi-SCF-CI-DV MO method and experimental spectra were consistent, thus suggesting that the conjugative effect of the cyclopropyl moiety is minimal. It was found that only the beta-cyclopropyl enantiomer 2a, but not the alpha-enantiomer 2b, binds to opsin. This observation, together with earlier retinal analogues incorporation results, led to the conclusion that the chromophore sinks into the N-terminal of the opsin receptor from the side of the 4-methylene and 15-aldehyde, and that the binding cleft accommodates 11-cis-retinal with a slightly positive twist around C12/C13. A reinterpretation of the previously published negative CD couplet of 11,12-dihydrorhodopsin also leads to a chromophoric C12/C13 twist conformation with the 13-Me in front as in 1b. Such a conformation for the chromophore accounts for both the observed biostereoselectivity of retCPr 2a and the observed negative couplet of 11,12-dihydro-Rh7.
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Affiliation(s)
- Yukari Fujimoto
- Department of Chemistry, Columbia University, New York, New York 10027, USA
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47
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Choi G, Landin J, Galan JF, Birge RR, Albert AD, Yeagle PL. Structural studies of metarhodopsin II, the activated form of the G-protein coupled receptor, rhodopsin. Biochemistry 2002; 41:7318-24. [PMID: 12044163 DOI: 10.1021/bi025507w] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The structural changes that accompany activation of a G-protein coupled receptor (GPCR) are not well understood. To better understand the activation of rhodopsin, the GPCR responsible for visual transduction, we report studies on the three-dimensional structure for the activated state of this receptor, metarhodopsin II. Differences between the three-dimensional structure of ground state rhodopsin and metarhodopsin II, particularly in the cytoplasmic face of the receptor, suggest how the receptor is activated to couple with transducin. In particular, activation opens a groove on the surface of the receptor that could bind the N-terminal helix of the G protein, transducin alpha.
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Affiliation(s)
- Gregory Choi
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, USA
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48
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Pan D, Ganim Z, Kim JE, Verhoeven MA, Lugtenburg J, Mathies RA. Time-resolved resonance Raman analysis of chromophore structural changes in the formation and decay of rhodopsin's BSI intermediate. J Am Chem Soc 2002; 124:4857-64. [PMID: 11971736 PMCID: PMC1440918 DOI: 10.1021/ja012666e] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Time-resolved resonance Raman microchip flow experiments are performed to obtain the vibrational spectrum of the chromophore in rhodopsin's BSI intermediate and to probe structural changes in the bathorhodopsin-to-BSI and BSI-to-lumirhodopsin transitions. Kinetic Raman spectra from 250 ns to 3 micros identify the key vibrational features of BSI. BSI exhibits relatively intense HOOP modes at 886 and 945 cm(-1) that are assigned to C(14)H and C(11)H=C(12)H A(u) wags, respectively. This result suggests that in the bathorhodopsin-to-BSI transition the highly strained all-trans chromophore has relaxed in the C(10)-C(11)=C(12)-C(13) region, but is still distorted near C(14). The low frequency of the 11,12 A(u) HOOP mode in BSI compared with that of lumirhodopsin and metarhodopsin I indicates weaker coupling between the 11H and 12H wags due to residual distortion of the BSI chromophore near C(11)=C(12). The C=NH(+) stretching mode in BSI at 1653 cm(-1) exhibits a normal deuteriation induced downshift of 23 cm(-1), implying that there is no significant structural rearrangement of the Schiff base counterion region in the transition of bathorhodopsin to BSI. However, a dramatic Schiff base environment change occurs in the BSI-to-lumirhodopsin transition, because the 1638 cm(-1) C=NH(+) stretching mode in lumirhodopsin is unusually low and shifts only 7 cm(-1) in D(2)O, suggesting that it has essentially no H-bonding acceptor. With these data we can for the first time compare and discuss the room temperature resonance Raman vibrational structure of all the key intermediates in visual excitation.
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Affiliation(s)
- Duohai Pan
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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49
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van Rossum BJ, Schulten EAM, Raap J, Oschkinat H, de Groot HJM. A 3-D structural model of solid self-assembled chlorophyll a/H(2)O from multispin labeling and MAS NMR 2-D dipolar correlation spectroscopy in high magnetic field. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2002; 155:1-14. [PMID: 11945028 DOI: 10.1006/jmre.2002.2502] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Magic angle spinning (MAS) NMR with Lee-Goldburg cross-polarization (LG-CP) is used to promote long-range heteronuclear transfer of magnetization and to constrain a structural model for uniformly labeled chlorophyll a/H(2)O. An effective maximum transfer range d(max) can be determined experimentally from the detection of a gradually decreasing series of intramolecular correlations with the (13)C along the molecular skeleton. To probe intermolecular contacts, d(max) can be set to approximately 4.2 A by choosing an LG-CP contact time of 2 ms. Long-range (1)H-(13)C correlations are used in conjunction with carbon and proton aggregation shifts to establish the stacking of the chlorophyll a (Chl a) molecules. First, high-field (14.1 T) 2-D MAS NMR homonuclear ((13)C-(13)C) dipolar correlation spectra provide a complete assignment of the carbon chemical shifts. Second, proton chemical shifts are obtained from (1)H-(13)C heteronuclear dipolar correlation spectroscopy in high magnetic field. The shift constraints and long-range (1)H-(13)C intermolecular correlations reveal a 2-D stacking homologous to the molecular arrangement in crystalline solid ethyl-chlorophyllide a. A doubling of a small subset of the carbon resonances, in the 7-methyl region of the molecule, provides evidence for two marginally different well-defined molecular environments. Evidence is found for the presence of neutral structural water molecules forming a hydrogen-bonded network to stabilize Chl a sheets. In line with the microcrystalline order observed for the rings, the long T(1)'s, and absence of conformational shifts for the (13)C in the phytyl tails, it is proposed that the Chl a form a rigid 3-D space-filling structure. Probably the only way this can be realized with the sheets is by forming bilayers with interpenetration of elongated tails. Such a 3-D space-filling organization of the aggregated Chl a from MAS NMR would match existing models inferred from electron microscopy and low-resolution X-ray powder diffraction, while a micellar model based on neutron diffraction and antiparallel stacking observed in solution can be discarded.
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Affiliation(s)
- Barth J van Rossum
- Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, The Netherlands
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Eilers M, Ying W, Reeves PJ, Khorana HG, Smith SO. Magic angle spinning nuclear magnetic resonance of isotopically labeled rhodopsin. Methods Enzymol 2002; 343:212-22. [PMID: 11675791 DOI: 10.1016/s0076-6879(02)43137-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Markus Eilers
- Department of Biochemistry and Cell Biology, State University of New York, Stony Brook, New York 11794, USA
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