1
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Wu Z, Sun X, Su J, Zhang X, Hu J, Li C. Revealing the graded activation mechanism of neurotensin receptor 1. Int J Biol Macromol 2024; 278:134488. [PMID: 39111461 DOI: 10.1016/j.ijbiomac.2024.134488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Revised: 08/02/2024] [Accepted: 08/02/2024] [Indexed: 08/16/2024]
Abstract
Graded activation contributes to the precise regulation of GPCR activity, presenting new opportunities for drug design. In this work, a total of 10 μs enhanced-sampling simulations are performed to provide molecular insights into the binding dynamics differences of the neurotensin receptor 1 (NTSR1) to the full agonist SRI-9829, partial agonist RTI-3a and inverse agonist SR48692. The possible graded activation mechanism of NTSR1 is revealed by an integrated analysis utilizing the reweighted potential of mean force (PMF), deep learning (DL) and transfer entropy (TE). Specifically, the orthosteric pocket is observed to undergo expansion and contraction, with the G-protein-binding site experiencing interconversions among the inactive, intermediate and active-like states. Detailed structural comparisons capture subtle conformational differences arising from ligand binding in allosteric signaling, which can well explain the graded activation. Critical microswitches that contribute to graded activation are efficiently identified with the DL model. TE calculations enable the visualization of allosteric communication networks within the receptor, elucidating the driver-responder relationships associated with signal transduction. Fortunately, the dissociation of the full agonist from the orthosteric pocket is observed. The current findings systematically reveal the mechanism of NTSR1 graded activation, and also provide implications for structure-based drug design.
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Affiliation(s)
- Zhixiang Wu
- College of Chemistry and Life Science, Beijing University of Technology, Beijing, China
| | - Xiaohan Sun
- College of Chemistry and Life Science, Beijing University of Technology, Beijing, China
| | - Jingjie Su
- College of Chemistry and Life Science, Beijing University of Technology, Beijing, China
| | - Xinyu Zhang
- College of Chemistry and Life Science, Beijing University of Technology, Beijing, China
| | - Jianping Hu
- Key Laboratory of Medicinal and Edible Plants Resources Development of Sichuan Education Department, School of Pharmacy, Chengdu University, Chengdu, China.
| | - Chunhua Li
- College of Chemistry and Life Science, Beijing University of Technology, Beijing, China.
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2
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Hong JD, Palczewski K. A short story on how chromophore is hydrolyzed from rhodopsin for recycling. Bioessays 2023; 45:e2300068. [PMID: 37454357 PMCID: PMC10614701 DOI: 10.1002/bies.202300068] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 05/24/2023] [Accepted: 05/30/2023] [Indexed: 07/18/2023]
Abstract
The photocycle of visual opsins is essential to maintain the light sensitivity of the retina. The early physical observations of the rhodopsin photocycle by Böll and Kühne in the 1870s inspired over a century's worth of investigations on rhodopsin biochemistry. A single photon isomerizes the Schiff-base linked 11-cis-retinylidene chromophore of rhodopsin, converting it to the all-trans agonist to elicit phototransduction through photoactivated rhodopsin (Rho*). Schiff base hydrolysis of the agonist is a key step in the photocycle, not only diminishing ongoing phototransduction but also allowing for entry and binding of fresh 11-cis chromophore to regenerate the rhodopsin pigment and maintain light sensitivity. Many challenges have been encountered in measuring the rate of this hydrolysis, but recent advancements have facilitated studies of the hydrolysis within the native membrane environment of rhodopsin. These techniques can now be applied to study hydrolysis of agonist in other opsin proteins that mediate phototransduction or chromophore turnover. In this review, we discuss the progress that has been made in characterizing the rhodopsin photocycle and the journey to characterize the hydrolysis of its all-trans-retinylidene agonist.
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Affiliation(s)
- John D. Hong
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California Irvine, Irvine, CA 92697, USA
- Department of Chemistry, University of California Irvine, Irvine, CA 92697, USA
| | - Krzysztof Palczewski
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California Irvine, Irvine, CA 92697, USA
- Department of Chemistry, University of California Irvine, Irvine, CA 92697, USA
- Department of Physiology and Biophysics, University of California Irvine, Irvine, CA 92697, USA
- Department of Molecular Biology and Biochemistry, University of California Irvine, Irvine, CA 92697, USA
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3
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Ren L, Jing Z, Xia F, Zhang JZ, Li Y. Toxic Effect of Fullerene and Its Derivatives upon the Transmembrane β2-Adrenergic Receptors. Molecules 2022; 27:molecules27144562. [PMID: 35889435 PMCID: PMC9323646 DOI: 10.3390/molecules27144562] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 06/28/2022] [Accepted: 07/10/2022] [Indexed: 12/04/2022] Open
Abstract
Numerous experiments have revealed that fullerene (C60) and its derivatives can bind to proteins and affect their biological functions. In this study, we explored the interaction between fullerine and the β2-adrenergic receptor (β2AR). The MD simulation results show that fullerene binds with the extracellular loop 2 (ECL2) and intracellular loop 2 (ICL2) of β2AR through hydrophobic interactions and π–π stacking interactions. In the C60_in1 trajectory, due to the π–π stacking interactions of fullerene molecules with PHE and PRO residues on ICL2, ICL2 completely flipped towards the fullerene direction and the fullerene moved slowly into the lipid membrane. When five fullerene molecules were placed on the extracellular side, they preferred to stack into a stable fullerene cluster (a deformed tetrahedral aggregate), and had almost no effect on the structure of β2AR. The hydroxyl groups of fullerene derivatives (C60(OH)X, X represents the number of hydroxyl groups, X = 4, 8) can form strong hydrogen bonds with the ECL2, helix6, and helix7 of β2AR. The hydroxyl groups firmly grasp the β2AR receptor like several claws, blocking the binding entry of ligands. The simulation results show that fullerene and fullerene derivatives may have a significant effect on the local structure of β2AR, especially the distortion of helix4, but bring about no great changes within the overall structure. It was found that C60 did not compete with ligands for binding sites, but blocked the ligands’ entry into the pocket channel. All the above observations suggest that fullerene and its derivatives exhibit certain cytotoxicity.
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Affiliation(s)
- Longlong Ren
- College of Mechanical and Electronic Engineering, Shandong Agricultural University, Tai’an 271018, China; (L.R.); (Z.J.)
| | - Zhenxiang Jing
- College of Mechanical and Electronic Engineering, Shandong Agricultural University, Tai’an 271018, China; (L.R.); (Z.J.)
| | - Fei Xia
- NYU-ECNU Center for Computational Chemistry at NYU Shanghai, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, China; (F.X.); (J.Z.Z.)
| | - John Zenghui Zhang
- NYU-ECNU Center for Computational Chemistry at NYU Shanghai, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, China; (F.X.); (J.Z.Z.)
| | - Yang Li
- College of Information Science and Engineering, Shandong Agricultural University, Tai’an 271018, China
- Correspondence:
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4
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Wang Y, Li M, Liang W, Shi X, Fan J, Kong R, Liu Y, Zhang J, Chen T, Lu S. Delineating the activation mechanism and conformational landscape of a class B G protein-coupled receptor glucagon receptor. Comput Struct Biotechnol J 2022; 20:628-639. [PMID: 35140883 PMCID: PMC8801358 DOI: 10.1016/j.csbj.2022.01.015] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 01/17/2022] [Accepted: 01/17/2022] [Indexed: 02/09/2023] Open
Abstract
Class B G protein-coupled receptors (GPCRs) are important targets in the treatment of metabolic syndrome and diabetes. Although multiple structures of class B GPCRs-G protein complexes have been elucidated, the detailed activation mechanism of the receptors remains unclear. Here, we combine Gaussian accelerated molecular dynamics simulations and Markov state models (MSM) to investigate the activation mechanism of a canonical class B GPCR, human glucagon receptor-GCGR, including the negative allosteric modulator-bound inactive state, the agonist glucagon-bound active state, and both glucagon- and Gs-bound fully active state. The free-energy landscapes of GCGR show the conformational ensemble consisting of three activation-associated states: inactive, active, and fully active. The structural analysis indicates the high dynamics of GCGR upon glucagon binding with both active and inactive conformations in the ensemble. Significantly, the H8 and TM6 exhibits distinct features from the inactive to the active states. The additional simulations demonstrate the role of H8 in the recruitment of Gs. Gs binding presents a crucial function of stabilizing the glucagon binding site and MSM highlights the absolute requirement of Gs to help the GCGR reach the fully active state. Together, our results reveal the detailed activation mechanism of GCGR from the view of conformational dynamics.
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Affiliation(s)
- Ying Wang
- Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University, School of Medicine, Shanghai 200025, China
- Medicinal Chemistry and Bioinformatics Center, Shanghai Jiao Tong University, School of Medicine, Shanghai 200025, China
| | - Mingyu Li
- Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University, School of Medicine, Shanghai 200025, China
| | - Wenqi Liang
- Department of Emergency, Changhai Hospital, Naval Medical University, Shanghai 200433, China
| | - Xinchao Shi
- Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University, School of Medicine, Shanghai 200025, China
| | - Jigang Fan
- Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University, School of Medicine, Shanghai 200025, China
| | - Ren Kong
- Institute of Bioinformatics and Medical Engineering, School of Electrical and Information Engineering, Jiangsu University of Technology, Changzhou 213001, China
| | - Yaqin Liu
- Medicinal Chemistry and Bioinformatics Center, Shanghai Jiao Tong University, School of Medicine, Shanghai 200025, China
| | - Jian Zhang
- Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University, School of Medicine, Shanghai 200025, China
- Medicinal Chemistry and Bioinformatics Center, Shanghai Jiao Tong University, School of Medicine, Shanghai 200025, China
| | - Ting Chen
- Department of Cardiology, Changzheng Hospital, Naval Medical University, Shanghai 200023, China
| | - Shaoyong Lu
- Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University, School of Medicine, Shanghai 200025, China
- Medicinal Chemistry and Bioinformatics Center, Shanghai Jiao Tong University, School of Medicine, Shanghai 200025, China
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5
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Kapla J, Rodríguez-Espigares I, Ballante F, Selent J, Carlsson J. Can molecular dynamics simulations improve the structural accuracy and virtual screening performance of GPCR models? PLoS Comput Biol 2021; 17:e1008936. [PMID: 33983933 PMCID: PMC8186765 DOI: 10.1371/journal.pcbi.1008936] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 06/08/2021] [Accepted: 04/02/2021] [Indexed: 01/14/2023] Open
Abstract
The determination of G protein-coupled receptor (GPCR) structures at atomic resolution has improved understanding of cellular signaling and will accelerate the development of new drug candidates. However, experimental structures still remain unavailable for a majority of the GPCR family. GPCR structures and their interactions with ligands can also be modelled computationally, but such predictions have limited accuracy. In this work, we explored if molecular dynamics (MD) simulations could be used to refine the accuracy of in silico models of receptor-ligand complexes that were submitted to a community-wide assessment of GPCR structure prediction (GPCR Dock). Two simulation protocols were used to refine 30 models of the D3 dopamine receptor (D3R) in complex with an antagonist. Close to 60 μs of simulation time was generated and the resulting MD refined models were compared to a D3R crystal structure. In the MD simulations, the receptor models generally drifted further away from the crystal structure conformation. However, MD refinement was able to improve the accuracy of the ligand binding mode. The best refinement protocol improved agreement with the experimentally observed ligand binding mode for a majority of the models. Receptor structures with improved virtual screening performance, which was assessed by molecular docking of ligands and decoys, could also be identified among the MD refined models. Application of weak restraints to the transmembrane helixes in the MD simulations further improved predictions of the ligand binding mode and second extracellular loop. These results provide guidelines for application of MD refinement in prediction of GPCR-ligand complexes and directions for further method development.
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Affiliation(s)
- Jon Kapla
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Ismael Rodríguez-Espigares
- Research Programme on Biomedical Informatics (GRIB), Department of Experimental and Health Sciences of Pompeu Fabra University (UPF), Hospital del Mar Medical Research Institute (IMIM), Barcelona, Spain
| | - Flavio Ballante
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Jana Selent
- Research Programme on Biomedical Informatics (GRIB), Department of Experimental and Health Sciences of Pompeu Fabra University (UPF), Hospital del Mar Medical Research Institute (IMIM), Barcelona, Spain
| | - Jens Carlsson
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
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6
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Ligand modulation of the conformational dynamics of the A 2A adenosine receptor revealed by single-molecule fluorescence. Sci Rep 2021; 11:5910. [PMID: 33723285 PMCID: PMC7960716 DOI: 10.1038/s41598-021-84069-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 02/11/2021] [Indexed: 02/07/2023] Open
Abstract
G protein-coupled receptors (GPCRs) are the largest class of transmembrane proteins, making them an important target for therapeutics. Activation of these receptors is modulated by orthosteric ligands, which stabilize one or several states within a complex conformational ensemble. The intra- and inter-state dynamics, however, is not well documented. Here, we used single-molecule fluorescence to measure ligand-modulated conformational dynamics of the adenosine A2A receptor (A2AR) on nanosecond to millisecond timescales. Experiments were performed on detergent-purified A2R in either the ligand-free (apo) state, or when bound to an inverse, partial or full agonist ligand. Single-molecule Förster resonance energy transfer (smFRET) was performed on detergent-solubilized A2AR to resolve active and inactive states via the separation between transmembrane (TM) helices 4 and 6. The ligand-dependent changes of the smFRET distributions are consistent with conformational selection and with inter-state exchange lifetimes ≥ 3 ms. Local conformational dynamics around residue 2296.31 on TM6 was measured using fluorescence correlation spectroscopy (FCS), which captures dynamic quenching due to photoinduced electron transfer (PET) between a covalently-attached dye and proximal aromatic residues. Global analysis of PET-FCS data revealed fast (150-350 ns), intermediate (50-60 μs) and slow (200-300 μs) conformational dynamics in A2AR, with lifetimes and amplitudes modulated by ligands and a G-protein mimetic (mini-Gs). Most notably, the agonist binding and the coupling to mini-Gs accelerates and increases the relative contribution of the sub-microsecond phase. Molecular dynamics simulations identified three tyrosine residues (Y112, Y2887.53, and Y2907.55) as being responsible for the dynamic quenching observed by PET-FCS and revealed associated helical motions around residue 2296.31 on TM6. This study provides a quantitative description of conformational dynamics in A2AR and supports the idea that ligands bias not only GPCR conformations but also the dynamics within and between distinct conformational states of the receptor.
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7
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Conrad M, Söldner CA, Miao Y, Sticht H. Agonist Binding and G Protein Coupling in Histamine H 2 Receptor: A Molecular Dynamics Study. Int J Mol Sci 2020; 21:ijms21186693. [PMID: 32932742 PMCID: PMC7554837 DOI: 10.3390/ijms21186693] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 09/04/2020] [Accepted: 09/08/2020] [Indexed: 02/06/2023] Open
Abstract
The histamine H2 receptor (H2R) plays an important role in the regulation of gastric acid secretion. Therefore, it is a main drug target for the treatment of gastroesophageal reflux or peptic ulcer disease. However, there is as of yet no 3D-structural information available hampering a mechanistic understanding of H2R. Therefore, we created a model of the histamine-H2R-Gs complex based on the structure of the ternary complex of the β2-adrenoceptor and investigated the conformational stability of this active GPCR conformation. Since the physiologically relevant motions with respect to ligand binding and conformational changes of GPCRs can only partly be assessed on the timescale of conventional MD (cMD) simulations, we also applied metadynamics and Gaussian accelerated molecular dynamics (GaMD) simulations. A multiple walker metadynamics simulation in combination with cMD was applied for the determination of the histamine binding mode. The preferential binding pose detected is in good agreement with previous data from site directed mutagenesis and provides a basis for rational ligand design. Inspection of the H2R-Gs interface reveals a network of polar interactions that may contribute to H2R coupling selectivity. The cMD and GaMD simulations demonstrate that the active conformation is retained on a μs-timescale in the ternary histamine-H2R-Gs complex and in a truncated complex that contains only Gs helix α5 instead of the entire G protein. In contrast, histamine alone is unable to stabilize the active conformation, which is in line with previous studies of other GPCRs.
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Affiliation(s)
- Marcus Conrad
- Bioinformatik, Institut für Biochemie, Emil-Fischer-Centrum, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Fahrstraße 17, 91054 Erlangen, Germany; (M.C.); (C.A.S.)
| | - Christian A. Söldner
- Bioinformatik, Institut für Biochemie, Emil-Fischer-Centrum, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Fahrstraße 17, 91054 Erlangen, Germany; (M.C.); (C.A.S.)
| | - Yinglong Miao
- Department of Computational Biology and Molecular Biosciences, University of Kansas, Lawrence, KS 66047, USA;
| | - Heinrich Sticht
- Bioinformatik, Institut für Biochemie, Emil-Fischer-Centrum, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Fahrstraße 17, 91054 Erlangen, Germany; (M.C.); (C.A.S.)
- Correspondence:
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8
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Grottesi A, Bešker N, Emerson A, Manelfi C, Beccari AR, Frigerio F, Lindahl E, Cerchia C, Talarico C. Computational Studies of SARS-CoV-2 3CLpro: Insights from MD Simulations. Int J Mol Sci 2020; 21:ijms21155346. [PMID: 32731361 PMCID: PMC7432786 DOI: 10.3390/ijms21155346] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 07/24/2020] [Accepted: 07/25/2020] [Indexed: 12/11/2022] Open
Abstract
Given the enormous social and health impact of the pandemic triggered by severe acute respiratory syndrome 2 (SARS-CoV-2), the scientific community made a huge effort to provide an immediate response to the challenges posed by Coronavirus disease 2019 (COVID-19). One of the most important proteins of the virus is an enzyme, called 3CLpro or main protease, already identified as an important pharmacological target also in SARS and Middle East respiratory syndrome virus (MERS) viruses. This protein triggers the production of a whole series of enzymes necessary for the virus to carry out its replicating and infectious activities. Therefore, it is crucial to gain a deeper understanding of 3CLpro structure and function in order to effectively target this enzyme. All-atoms molecular dynamics (MD) simulations were performed to examine the different conformational behaviors of the monomeric and dimeric form of SARS-CoV-2 3CLpro apo structure, as revealed by microsecond time scale MD simulations. Our results also shed light on the conformational dynamics of the loop regions at the entry of the catalytic site. Studying, at atomic level, the characteristics of the active site and obtaining information on how the protein can interact with its substrates will allow the design of molecules able to block the enzymatic function crucial for the virus.
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Affiliation(s)
| | - Neva Bešker
- Department HPC, CINECA, via dei Tizii 6, 00185 Roma, Italy; (A.G.); (N.B.)
| | - Andrew Emerson
- Department HPC, CINECA, via Magnanelli 6/3, 40033 Casalecchio di Reno (BO), Italy;
| | - Candida Manelfi
- Dompé Farmaceutici SpA, via Campo di Pile, 67100 L’Aquila, Italy; (C.M.); (A.R.B.)
| | - Andrea R. Beccari
- Dompé Farmaceutici SpA, via Campo di Pile, 67100 L’Aquila, Italy; (C.M.); (A.R.B.)
| | - Francesco Frigerio
- Department Physical Chemistry, R&D, Eni SpA, via Maritano 27, 20097 San Donato Milanese (MI), Italy;
| | - Erik Lindahl
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, 17165 Solna, Sweden;
| | - Carmen Cerchia
- Department of Pharmacy, University of Napoli “Federico II”, via D. Montesano 49, 80131 Napoli, Italy;
| | - Carmine Talarico
- Dompé Farmaceutici SpA, via Campo di Pile, 67100 L’Aquila, Italy; (C.M.); (A.R.B.)
- Correspondence: ; Tel.: +39-34-8379-6369
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9
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Structural basis of ligand recognition and self-activation of orphan GPR52. Nature 2020; 579:152-157. [PMID: 32076264 DOI: 10.1038/s41586-020-2019-0] [Citation(s) in RCA: 91] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 01/23/2020] [Indexed: 11/08/2022]
Abstract
GPR52 is a class-A orphan G-protein-coupled receptor that is highly expressed in the brain and represents a promising therapeutic target for the treatment of Huntington's disease and several psychiatric disorders1,2. Pathological malfunction of GPR52 signalling occurs primarily through the heterotrimeric Gs protein2, but it is unclear how GPR52 and Gs couple for signal transduction and whether a native ligand or other activating input is required. Here we present the high-resolution structures of human GPR52 in three states: a ligand-free state, a Gs-coupled self-activation state and a potential allosteric ligand-bound state. Together, our structures reveal that extracellular loop 2 occupies the orthosteric binding pocket and operates as a built-in agonist, conferring an intrinsically high level of basal activity to GPR523. A fully active state is achieved when Gs is coupled to GPR52 in the absence of an external agonist. The receptor also features a side pocket for ligand binding. These insights into the structure and function of GPR52 could improve our understanding of other self-activated GPCRs, enable the identification of endogenous and tool ligands, and guide drug discovery efforts that target GPR52.
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10
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Ryazantsev MN, Nikolaev DM, Struts AV, Brown MF. Quantum Mechanical and Molecular Mechanics Modeling of Membrane-Embedded Rhodopsins. J Membr Biol 2019; 252:425-449. [PMID: 31570961 DOI: 10.1007/s00232-019-00095-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 09/10/2019] [Indexed: 12/20/2022]
Abstract
Computational chemistry provides versatile methods for studying the properties and functioning of biological systems at different levels of precision and at different time scales. The aim of this article is to review the computational methodologies that are applicable to rhodopsins as archetypes for photoactive membrane proteins that are of great importance both in nature and in modern technologies. For each class of computational techniques, from methods that use quantum mechanics for simulating rhodopsin photophysics to less-accurate coarse-grained methodologies used for long-scale protein dynamics, we consider possible applications and the main directions for improvement.
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Affiliation(s)
- Mikhail N Ryazantsev
- Institute of Chemistry, Saint Petersburg State University, 26 Universitetskii pr, Saint Petersburg, Russia, 198504
| | - Dmitrii M Nikolaev
- Saint-Petersburg Academic University - Nanotechnology Research and Education Centre RAS, Saint Petersburg, Russia, 194021
| | - Andrey V Struts
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, USA.,Laboratory of Biomolecular NMR, Saint Petersburg State University, Saint Petersburg, Russia, 199034
| | - Michael F Brown
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, USA. .,Department of Physics, University of Arizona, Tucson, AZ, 85721, USA.
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11
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Abstract
G protein-coupled receptors (GPCRs) mediate the majority of cellular responses to external stimuli. Upon activation by a ligand, the receptor binds to a partner heterotrimeric G protein and promotes exchange of GTP for GDP, leading to dissociation of the G protein into α and βγ subunits that mediate downstream signals. GPCRs can also activate distinct signaling pathways through arrestins. Active states of GPCRs form by small rearrangements of the ligand-binding, or orthosteric, site that are amplified into larger conformational changes. Molecular understanding of the allosteric coupling between ligand binding and G protein or arrestin interaction is emerging from structures of several GPCRs crystallized in inactive and active states, spectroscopic data, and computer simulations. The coupling is loose, rather than concerted, and agonist binding does not fully stabilize the receptor in an active conformation. Distinct intermediates whose populations are shifted by ligands of different efficacies underlie the complex pharmacology of GPCRs.
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Affiliation(s)
- William I Weis
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305, USA; .,Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California 94305, USA;
| | - Brian K Kobilka
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California 94305, USA;
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12
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Martínez-Archundia M, Correa-Basurto J, Montaño S, Rosas-Trigueros JL. Studying the collective motions of the adenosine A2A receptor as a result of ligand binding using principal component analysis. J Biomol Struct Dyn 2019; 37:4685-4700. [DOI: 10.1080/07391102.2018.1564700] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Marlet Martínez-Archundia
- Laboratorio de Modelado Molecular y Bioinformática, Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional, Mexico City, Mexico
| | - José Correa-Basurto
- Laboratorio de Modelado Molecular y Bioinformática, Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional, Mexico City, Mexico
| | - Sarita Montaño
- Facultad de Ciencias Químico Biológicas, Universidad Autónoma de Sinaloa, Culiacan, Sinaloa, Mexico
| | - Jorge L. Rosas-Trigueros
- Laboratorio Transdisciplinario de Investigación en Sistemas Evolutivos, Sección de Estudios de Posgrado e Investigación, Escuela Superior de Cómputo, Instituto Politécnico Nacional, Mexico City, Mexico
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13
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Gao N, Liang T, Yuan Y, Xiao X, Zhao Y, Guo Y, Li M, Pu X. Exploring the mechanism of F282L mutation-caused constitutive activity of GPCR by a computational study. Phys Chem Chem Phys 2018; 18:29412-29422. [PMID: 27735961 DOI: 10.1039/c6cp03710k] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
G-protein-coupled receptors (GPCRs) are important drug targets and generally activated by ligands. However, some experiments found that GPCRs also give rise to constitutive activity through some mutations (viz., CAM), which are usually associated with different kinds of diseases. However, the mechanisms of CAMs and their roles in interactions with drug-ligands are unclear in experiments. Herein, we used microsecond molecular dynamics simulations to study the effect of one important F282L mutation on β2AR in order to address the questions above. With the aid of principle component and correlation analysis, our results revealed that the F282L mutation could increase the instability of the overall structure, increase the dramatic fluctuations of NPxxY and extracellular loops, and decrease restraint of the helices through weakening interhelical H-bonding and correlations between residues, which could partly contribute to the constitutive activity reported by the experiments. The observations from the protein structure network (PSN) analysis indicate that the mutant exhibits less information flow than the wild β2AR and weakens the role of TM5 and TM6 in the signal transmission, but it enhances the impact of TM3 on the orthosteric pathway and TM4 on the allosteric one. In addition, the results from the virtual screening reveal that the mutant prefers to select agonists rather than antagonists, similar to the active state but opposite of the inactive state, further confirming that the F282L mutation advances the activation of β2AR. Our observations provide valuable information for understanding the mechanism of the mutation-caused constitutive activity of GPCR and related drug-design.
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Affiliation(s)
- Nan Gao
- Faculty of Chemistry, Sichuan University, Chengdu, Sichuan 610064, People's Republic of China.
| | - Tao Liang
- Faculty of Chemistry, Sichuan University, Chengdu, Sichuan 610064, People's Republic of China.
| | - Yuan Yuan
- College of Management, Southwest University for Nationalities, Chengdu 610041, P. R. China
| | - Xiuchan Xiao
- Department of Architecture and Environmental Engineering, Chengdu Technological University, Chengdu, Sichuan 611730, China
| | - Yihuan Zhao
- Faculty of Chemistry, Sichuan University, Chengdu, Sichuan 610064, People's Republic of China.
| | - Yanzhi Guo
- Faculty of Chemistry, Sichuan University, Chengdu, Sichuan 610064, People's Republic of China.
| | - Menglong Li
- Faculty of Chemistry, Sichuan University, Chengdu, Sichuan 610064, People's Republic of China.
| | - Xuemei Pu
- Faculty of Chemistry, Sichuan University, Chengdu, Sichuan 610064, People's Republic of China.
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14
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Lynch DL, Hurst DP, Shore DM, Pitman MC, Reggio PH. Molecular Dynamics Methodologies for Probing Cannabinoid Ligand/Receptor Interaction. Methods Enzymol 2017; 593:449-490. [PMID: 28750815 PMCID: PMC5802876 DOI: 10.1016/bs.mie.2017.05.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The cannabinoid type 1 and 2 G-protein-coupled receptors are currently important pharmacological targets with significant drug discovery potential. These receptors have been shown to display functional selectivity or biased agonism, a property currently thought to have substantial therapeutic potential. Although recent advances in crystallization techniques have provided a wealth of structural information about this important class of membrane-embedded proteins, these structures lack dynamical information. In order to fully understand the interplay of structure and function for this important class of proteins, complementary techniques that address the dynamical aspects of their function are required such as NMR as well as a variety of other spectroscopies. Complimentary to these experimental approaches is molecular dynamics, which has been effectively used to help unravel, at the atomic level, the dynamics of ligand binding and activation of these membrane-bound receptors. Here, we discuss and present several representative examples of the application of molecular dynamics simulations to the understanding of the signatures of ligand-binding and -biased signaling at the cannabinoid type 1 and 2 receptors.
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Affiliation(s)
- Diane L Lynch
- University of North Carolina at Greensboro, Greensboro, NC, United States.
| | - Dow P Hurst
- University of North Carolina at Greensboro, Greensboro, NC, United States
| | - Derek M Shore
- University of North Carolina at Greensboro, Greensboro, NC, United States
| | - Mike C Pitman
- University of North Carolina at Greensboro, Greensboro, NC, United States
| | - Patricia H Reggio
- University of North Carolina at Greensboro, Greensboro, NC, United States
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15
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Rovati GE, Capra V, Shaw VS, Malik RU, Sivaramakrishnan S, Neubig RR. The DRY motif and the four corners of the cubic ternary complex model. Cell Signal 2017; 35:16-23. [PMID: 28347873 DOI: 10.1016/j.cellsig.2017.03.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 03/24/2017] [Indexed: 12/14/2022]
Abstract
Recent structural data on GPCRs using a variety of spectroscopic approaches suggest that GPCRs adopt a dynamic conformational landscape, with ligands stabilizing subsets of these states to activate one or more downstream signaling effectors. A key outstanding question posed by this emerging dynamic structural model of GPCRs is what states, active, inactive, or intermediate are captured by the numerous crystal structures of GPCRs complexed with a variety of agonists, partial agonists, and antagonists. In the early nineties the discovery of inverse agonists and constitutive activity led to the idea that the active receptor state (R⁎) is an intrinsic property of the receptor itself rather than of the RG complex, eventually leading to the formulation of the cubic ternary complex model (CTC). Here, by a careful analysis of a series of data obtained with a number of mutants of the highly conserved E/DRY motif, we show evidences for the existence of all the receptor states theorized by the CTC, four 'uncoupled (R, R⁎ and HR and HR⁎), and, consequently four 'coupled' (RG, R⁎G, HRG and HR⁎G). The E/DRY motif located at the cytosolic end of transmembrane helix III of Class A GPCRs has been widely studied and analyzed because it forms a network of interactions believed to lock receptors in the inactive conformation (R), and, thus, to play a key role in receptor activation. Our conclusions are supported by recent crystal and NMR spectra, as well as by results obtained with two prototypical GPCRs using a new FRET technology that de-couples G protein binding to the receptor from signal transduction. Thus, despite its complexity and limitations, we propose that the CTC is a useful framework to reconcile pharmacological, biochemical and structural data.
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Affiliation(s)
- G Enrico Rovati
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milano, Italy.
| | - Valérie Capra
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milano, Italy; Department of Health Science, University of Milan, Milano, Italy.
| | - Vincent S Shaw
- Department of Pharmacology & Toxicology, Michigan State University, East Lansing, MI, USA.
| | - Rabia U Malik
- Department of Genetics, Cell Biology & Development, College of Biological Sciences, University of Minnesota Twin Cities, Minneapolis, MN, USA.
| | - Sivaraj Sivaramakrishnan
- Department of Genetics, Cell Biology & Development, College of Biological Sciences, University of Minnesota Twin Cities, Minneapolis, MN, USA.
| | - Richard R Neubig
- Department of Pharmacology & Toxicology, Michigan State University, East Lansing, MI, USA.
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16
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Affiliation(s)
- Naomi R. Latorraca
- Department of Computer Science, ‡Biophysics Program, §Department of Molecular
and Cellular
Physiology, and ∥Institute for Computational and Mathematical Engineering, Stanford University, Stanford, California 94305, United States
| | - A. J. Venkatakrishnan
- Department of Computer Science, ‡Biophysics Program, §Department of Molecular
and Cellular
Physiology, and ∥Institute for Computational and Mathematical Engineering, Stanford University, Stanford, California 94305, United States
| | - Ron O. Dror
- Department of Computer Science, ‡Biophysics Program, §Department of Molecular
and Cellular
Physiology, and ∥Institute for Computational and Mathematical Engineering, Stanford University, Stanford, California 94305, United States
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17
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Neale C, Herce HD, Pomès R, García AE. Can Specific Protein-Lipid Interactions Stabilize an Active State of the Beta 2 Adrenergic Receptor? Biophys J 2016; 109:1652-62. [PMID: 26488656 DOI: 10.1016/j.bpj.2015.08.028] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 08/21/2015] [Accepted: 08/24/2015] [Indexed: 11/16/2022] Open
Abstract
G-protein-coupled receptors are eukaryotic membrane proteins with broad biological and pharmacological relevance. Like all membrane-embedded proteins, their location and orientation are influenced by lipids, which can also impact protein function via specific interactions. Extensive simulations totaling 0.25 ms reveal a process in which phospholipids from the membrane's cytosolic leaflet enter the empty G-protein binding site of an activated β2 adrenergic receptor and form salt-bridge interactions that inhibit ionic lock formation and prolong active-state residency. Simulations of the receptor embedded in an anionic membrane show increased lipid binding, providing a molecular mechanism for the experimental observation that anionic lipids can enhance receptor activity. Conservation of the arginine component of the ionic lock among Rhodopsin-like G-protein-coupled receptors suggests that intracellular lipid ingression between receptor helices H6 and H7 may be a general mechanism for active-state stabilization.
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Affiliation(s)
- Chris Neale
- Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, Troy, New York
| | - Henry D Herce
- Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, Troy, New York
| | - Régis Pomès
- Molecular Structure and Function, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Angel E García
- Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, Troy, New York; Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York.
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18
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Manna M, Kulig W, Javanainen M, Tynkkynen J, Hensen U, Müller DJ, Rog T, Vattulainen I. How To Minimize Artifacts in Atomistic Simulations of Membrane Proteins, Whose Crystal Structure Is Heavily Engineered: β₂-Adrenergic Receptor in the Spotlight. J Chem Theory Comput 2016; 11:3432-45. [PMID: 26575777 DOI: 10.1021/acs.jctc.5b00070] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Atomistic molecular dynamics (MD) simulations are used extensively to elucidate membrane protein properties. These simulations are based on three-dimensional protein structures that in turn are often based on crystallography. The protein structures resolved in crystallographic studies typically do not correspond to pristine proteins, however. Instead the crystallized proteins are commonly engineered, including structural modifications (mutations, replacement of protein sequences by antibodies, bound ligands, etc.) whose impact on protein structure and dynamics is largely unknown. Here we explore this issue through atomistic MD simulations (∼5 μs in total), focusing on the β2-adrenergic receptor (β2AR) that is one of the most studied members of the G-protein coupled receptor superfamily. Starting from an inactive-state crystal structure of β2AR, we remove the many modifications in β2AR systematically one at a time, in six consecutive steps. After each step, we equilibrate the system and simulate it quite extensively. The results of this step-by-step approach highlight that the structural modifications used in crystallization can affect ligand and G-protein binding sites, packing at the transmembrane-helix interface region, and the dynamics of connecting loops in β2AR. When the results of the systematic step-by-step approach are compared to an all-at-once technique where all modifications done on β2AR are removed instantaneously at the same time, it turns out that the step-by-step method provides results that are superior in terms of maintaining protein structural stability. The results provide compelling evidence that for membrane proteins whose 3D structure is based on structural engineering, the preparation of protein structure for atomistic MD simulations is a delicate and sensitive process. The results show that most valid results are found when the structural modifications are reverted slowly, one at a time.
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Affiliation(s)
- Moutusi Manna
- Department of Physics, Tampere University of Technology , P.O. Box 692, FI-33101 Tampere, Finland
| | - Waldemar Kulig
- Department of Physics, Tampere University of Technology , P.O. Box 692, FI-33101 Tampere, Finland
| | - Matti Javanainen
- Department of Physics, Tampere University of Technology , P.O. Box 692, FI-33101 Tampere, Finland
| | - Joona Tynkkynen
- Department of Physics, Tampere University of Technology , P.O. Box 692, FI-33101 Tampere, Finland
| | - Ulf Hensen
- Department of Biosystems Science and Engineering (D-BSSE), ETH-Zürich , 4058 Basel, Switzerland
| | - Daniel J Müller
- Department of Biosystems Science and Engineering (D-BSSE), ETH-Zürich , 4058 Basel, Switzerland
| | - Tomasz Rog
- Department of Physics, Tampere University of Technology , P.O. Box 692, FI-33101 Tampere, Finland
| | - Ilpo Vattulainen
- Department of Physics, Tampere University of Technology , P.O. Box 692, FI-33101 Tampere, Finland.,MEMPHYS-Center for Biomembrane Physics, University of Southern Denmark , Odense, Denmark
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19
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Topiol S, Sabio M. The role of experimental and computational structural approaches in 7TM drug discovery. Expert Opin Drug Discov 2015. [DOI: 10.1517/17460441.2015.1072166] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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20
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Romo TD, Leioatts N, Grossfield A. Lightweight object oriented structure analysis: tools for building tools to analyze molecular dynamics simulations. J Comput Chem 2014; 35:2305-18. [PMID: 25327784 PMCID: PMC4227929 DOI: 10.1002/jcc.23753] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 09/07/2014] [Indexed: 01/13/2023]
Abstract
LOOS (Lightweight Object Oriented Structure-analysis) is a C++ library designed to facilitate making novel tools for analyzing molecular dynamics simulations by abstracting out the repetitive tasks, allowing developers to focus on the scientifically relevant part of the problem. LOOS supports input using the native file formats of most common biomolecular simulation packages, including CHARMM, NAMD, Amber, Tinker, and Gromacs. A dynamic atom selection language based on the C expression syntax is included and is easily accessible to the tool-writer. In addition, LOOS is bundled with over 140 prebuilt tools, including suites of tools for analyzing simulation convergence, three-dimensional histograms, and elastic network models. Through modern C++ design, LOOS is both simple to develop with (requiring knowledge of only four core classes and a few utility functions) and is easily extensible. A python interface to the core classes is also provided, further facilitating tool development.
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Affiliation(s)
- Tod D Romo
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, New York, 14642
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21
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Shahane G, Parsania C, Sengupta D, Joshi M. Molecular insights into the dynamics of pharmacogenetically important N-terminal variants of the human β2-adrenergic receptor. PLoS Comput Biol 2014; 10:e1004006. [PMID: 25501358 PMCID: PMC4263363 DOI: 10.1371/journal.pcbi.1004006] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Accepted: 10/28/2014] [Indexed: 12/27/2022] Open
Abstract
The human β2-adrenergic receptor (β2AR), a member of the G-protein coupled receptor (GPCR) family, is expressed in bronchial smooth muscle cells. Upon activation by agonists, β2AR causes bronchodilation and relief in asthma patients. The N-terminal polymorphism of β2AR at the 16th position, Arg16Gly, has warranted a lot of attention since it is linked to variations in response to albuterol (agonist) treatment. Although the β2AR is one of the well-studied GPCRs, the N-terminus which harbors this mutation, is absent in all available experimental structures. The goal of this work was to study the molecular level differences between the N-terminal variants using structural modeling and atomistic molecular dynamics simulations. Our simulations reveal that the N-terminal region of the Arg variant shows greater dynamics than the Gly variant, leading to differential placement. Further, the position and dynamics of the N-terminal region, further, affects the ligand binding-site accessibility. Interestingly, long-range effects are also seen at the ligand binding site, which is marginally larger in the Gly as compared to the Arg variant resulting in the preferential docking of albuterol to the Gly variant. This study thus reveals key differences between the variants providing a molecular framework towards understanding the variable drug response in asthma patients. The human β2-adrenergic receptor (β2AR) is an important member of the GPCR family and a mutation at the 16th position, Arg16Gly, is commonly found in the population. This variation in asthma patients is linked to differential (good/bad) response to the drug albuterol, an agonist of the β2AR. To date, the coordinates of the N-terminal residues harboring the 16th position mutation have not been resolved. In our study we sought to glean insights into the dynamics of the variants that could address the differential response to albuterol. We used knowledge from class A GPCRs to build the N-terminal region of β2AR variants in conjunction with the available structure of the inactive receptor. This was followed by atomistic simulations in triplicate totaling to a sampling of 6 µs. We observe that the N-terminal region of the Arg variant is more dynamic than the Gly variant. Amongst the various differences between the variants, we observe long-range effects at the binding site leading to preferential docking of albuterol to the Gly variant. Our work is a first step to unravel the molecular mechanism linking the Arg16Gly variation to the differential response to albuterol in asthma patients.
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Affiliation(s)
| | | | - Durba Sengupta
- CSIR-National Chemical Laboratory, Pune, India
- * E-mail: (DS); (MJ)
| | - Manali Joshi
- Bioinformatics Center, University of Pune, Pune, India
- * E-mail: (DS); (MJ)
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22
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Markutsya S, Lamm MH. A coarse-graining approach for molecular simulation that retains the dynamics of the all-atom reference system by implementing hydrodynamic interactions. J Chem Phys 2014; 141:174107. [DOI: 10.1063/1.4898625] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
| | - Monica H. Lamm
- Ames Laboratory, Iowa State University, Ames, Iowa 50011, USA
- Department of Chemical and Biological Engineering, Iowa State University, Ames, Iowa 50011, USA
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23
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Kusek J, Yang Q, Witek M, Gruber CW, Nanoff C, Freissmuth M. Chaperoning of the A1-adenosine receptor by endogenous adenosine - an extension of the retaliatory metabolite concept. Mol Pharmacol 2014; 87:39-51. [PMID: 25354767 DOI: 10.1124/mol.114.094045] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cell-permeable orthosteric ligands can assist folding of G protein-coupled receptors in the endoplasmic reticulum (ER); this pharmacochaperoning translates into increased cell surface levels of receptors. Here we used a folding-defective mutant of human A1-adenosine receptor as a sensor to explore whether endogenously produced adenosine can exert a chaperoning effect. This A1-receptor-Y(288)A was retained in the ER of stably transfected human embryonic kidney 293 cells but rapidly reached the plasma membrane in cells incubated with an A1 antagonist. This was phenocopied by raising intracellular adenosine levels with a combination of inhibitors of adenosine kinase, adenosine deaminase, and the equilibrative nucleoside transporter: mature receptors with complex glycosylation accumulated at the cell surface and bound to an A1-selective antagonist with an affinity indistinguishable from the wild-type A1 receptor. The effect of the inhibitor combination was specific, because it did not result in enhanced surface levels of two folding-defective human V2-vasopressin receptor mutants, which were susceptible to pharmacochaperoning by their cognate antagonist. Raising cellular adenosine levels by subjecting cells to hypoxia (5% O2) reproduced chaperoning by the inhibitor combination and enhanced surface expression of A1-receptor-Y(288)A within 1 hour. These findings were recapitulated for the wild-type A1 receptor. Taken together, our observations document that endogenously formed adenosine can chaperone its cognate A1 receptor. This results in a positive feedback loop that has implications for the retaliatory metabolite concept of adenosine action: if chaperoning by intracellular adenosine results in elevated cell surface levels of A1 receptors, these cells will be more susceptible to extracellular adenosine and thus more likely to cope with metabolic distress.
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Affiliation(s)
- Justyna Kusek
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Qiong Yang
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Martin Witek
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Christian W Gruber
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Christian Nanoff
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Michael Freissmuth
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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24
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Leioatts N, Suresh P, Romo TD, Grossfield A. Structure-based simulations reveal concerted dynamics of GPCR activation. Proteins 2014; 82:2538-51. [PMID: 24889093 DOI: 10.1002/prot.24617] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Revised: 05/06/2014] [Accepted: 05/20/2014] [Indexed: 11/08/2022]
Abstract
G protein-coupled receptors (GPCRs) are a vital class of proteins that transduce biological signals across the cell membrane. However, their allosteric activation mechanism is not fully understood; crystal structures of active and inactive receptors have been reported, but the functional pathway between these two states remains elusive. Here, we use structure-based (Gō-like) models to simulate activation of two GPCRs, rhodopsin and the β₂ adrenergic receptor (β₂AR). We used data-derived reaction coordinates that capture the activation mechanism for both proteins, showing that activation proceeds through quantitatively different paths in the two systems. Both reaction coordinates are determined from the dominant concerted motions in the simulations so the technique is broadly applicable. There were two surprising results. First, the main structural changes in the simulations were distributed throughout the transmembrane bundle, and not localized to the obvious areas of interest, such as the intracellular portion of Helix 6. Second, the activation (and deactivation) paths were distinctly nonmonotonic, populating states that were not simply interpolations between the inactive and active structures. These transitions also suggest a functional explanation for β₂AR's basal activity: it can proceed through a more broadly defined path during the observed transitions.
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Affiliation(s)
- Nicholas Leioatts
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, New York, 14642
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25
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Paramo T, East A, Garzón D, Ulmschneider MB, Bond PJ. Efficient Characterization of Protein Cavities within Molecular Simulation Trajectories: trj_cavity. J Chem Theory Comput 2014; 10:2151-64. [DOI: 10.1021/ct401098b] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Teresa Paramo
- Unilever
Centre for Molecular Science Informatics, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Alexandra East
- Unilever
Centre for Molecular Science Informatics, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Diana Garzón
- Unilever
Centre for Molecular Science Informatics, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Martin B. Ulmschneider
- Department
of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Peter J. Bond
- Unilever
Centre for Molecular Science Informatics, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
- Bioinformatics Institute (A*STAR), 30
Biopolis Str, #07-01 Matrix, Singapore 138671
- Department
of Biological Sciences, National University of Singapore, 14 Science
Drive 4, 117543 Singapore
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26
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Miao Y, Nichols SE, McCammon JA. Free energy landscape of G-protein coupled receptors, explored by accelerated molecular dynamics. Phys Chem Chem Phys 2014; 16:6398-406. [PMID: 24445284 PMCID: PMC3960983 DOI: 10.1039/c3cp53962h] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Accepted: 01/14/2014] [Indexed: 11/21/2022]
Abstract
G-protein coupled receptors (GPCRs) mediate cellular responses to various hormones and neurotransmitters and are important targets for treating a wide spectrum of diseases. They are known to adopt multiple conformational states (e.g., inactive, intermediate and active) during their modulation of various cell signaling pathways. Here, the free energy landscape of GPCRs is explored using accelerated molecular dynamics (aMD) simulations as demonstrated on the M2 muscarinic receptor, a key GPCR that regulates human heart rate and contractile forces of cardiomyocytes. Free energy profiles of important structural motifs that undergo conformational transitions upon GPCR activation and allosteric signaling are analyzed in detail, including the Arg(3.50)-Glu(6.30) ionic lock, the Trp(6.48) toggle switch and the hydrogen interactions between Tyr(5.58)-Tyr(7.53).
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Affiliation(s)
- Yinglong Miao
- Howard Hughes Medical Institute , University of California at San Diego , La Jolla , CA 92093 , USA .
| | - Sara E. Nichols
- Department of Chemistry and Biochemistry , University of California at San Diego , La Jolla , CA 92093 , USA .
- Department of Pharmacology , University of California at San Diego , La Jolla , CA 92093 , USA
| | - J. Andrew McCammon
- Howard Hughes Medical Institute , University of California at San Diego , La Jolla , CA 92093 , USA .
- Department of Chemistry and Biochemistry , University of California at San Diego , La Jolla , CA 92093 , USA .
- Department of Pharmacology , University of California at San Diego , La Jolla , CA 92093 , USA
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27
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Ramanathan A, Savol A, Burger V, Chennubhotla CS, Agarwal PK. Protein conformational populations and functionally relevant substates. Acc Chem Res 2014; 47:149-56. [PMID: 23988159 DOI: 10.1021/ar400084s] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Functioning proteins do not remain fixed in a unique structure, but instead they sample a range of conformations facilitated by motions within the protein. Even in the native state, a protein exists as a collection of interconverting conformations driven by thermodynamic fluctuations. Motions on the fast time scale allow a protein to sample conformations in the nearby area of its conformational landscape, while motions on slower time scales give it access to conformations in distal areas of the landscape. Emerging evidence indicates that protein landscapes contain conformational substates with dynamic and structural features that support the designated function of the protein. Nuclear magnetic resonance (NMR) experiments provide information about conformational ensembles of proteins. X-ray crystallography allows researchers to identify the most populated states along the landscape, and computational simulations give atom-level information about the conformational substates of different proteins. This ability to characterize and obtain quantitative information about the conformational substates and the populations of proteins within them is allowing researchers to better understand the relationship between protein structure and dynamics and the mechanisms of protein function. In this Account, we discuss recent developments and challenges in the characterization of functionally relevant conformational populations and substates of proteins. In some enzymes, the sampling of functionally relevant conformational substates is connected to promoting the overall mechanism of catalysis. For example, the conformational landscape of the enzyme dihydrofolate reductase has multiple substates, which facilitate the binding and the release of the cofactor and substrate and catalyze the hydride transfer. For the enzyme cyclophilin A, computational simulations reveal that the long time scale conformational fluctuations enable the enzyme to access conformational substates that allow it to attain the transition state, therefore promoting the reaction mechanism. In the long term, this emerging view of proteins with conformational substates has broad implications for improving our understanding of enzymes, enzyme engineering, and better drug design. Researchers have already used photoactivation to modulate protein conformations as a strategy to develop a hypercatalytic enzyme. In addition, the alteration of the conformational substates through binding of ligands at locations other than the active site provides the basis for the design of new medicines through allosteric modulation.
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Affiliation(s)
- Arvind Ramanathan
- Computational Science and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Andrej Savol
- Joint Carnegie Mellon University−University of Pittsburgh Ph.D Program in Computational Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Virginia Burger
- Joint Carnegie Mellon University−University of Pittsburgh Ph.D Program in Computational Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Chakra S. Chennubhotla
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Pratul K. Agarwal
- Annavitas Biosciences, 2519 Caspian Drive, Knoxville, Tennessee 37932, United States
- Computational Biology Institute, and Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
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28
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Novikov GV, Sivozhelezov VS, Shaitan KV. Investigation of the conformational dynamics of the A2A adenosine receptor by molecular dynamics simulation. Biophysics (Nagoya-shi) 2013. [DOI: 10.1134/s0006350913040131] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
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29
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Pruitt MM, Lamm MH, Coffman CR. Molecular dynamics simulations on the Tre1 G protein-coupled receptor: exploring the role of the arginine of the NRY motif in Tre1 structure. BMC STRUCTURAL BIOLOGY 2013; 13:15. [PMID: 24044607 PMCID: PMC3848830 DOI: 10.1186/1472-6807-13-15] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Accepted: 09/16/2013] [Indexed: 11/10/2022]
Abstract
BACKGROUND The arginine of the D/E/NRY motif in Rhodopsin family G protein-coupled receptors (GPCRs) is conserved in 96% of these proteins. In some GPCRs, this arginine in transmembrane 3 can form a salt bridge with an aspartic acid or glutamic acid in transmembrane 6. The Drosophila melanogaster GPCR Trapped in endoderm-1 (Tre1) is required for normal primordial germ cell migration. In a mutant form of the protein, Tre1sctt, eight amino acids RYILIACH are missing, resulting in a severe disruption of primordial germ cell development. The impact of the loss of these amino acids on Tre1 structure is unknown. Since the missing amino acids in Tre1sctt include the arginine that is part of the D/E/NRY motif in Tre1, molecular dynamics simulations were performed to explore the hypothesis that these amino acids are involved in salt bridge formation and help maintain Tre1 structure. RESULTS Structural predictions of wild type Tre1 (Tre1+) and Tre1sctt were subjected to over 250 ns of molecular dynamics simulations. The ability of the model systems to form a salt bridge between the arginine of the D/E/NRY motif and an aspartic acid residue in transmembrane 6 was analyzed. The results indicate that a stable salt bridge can form in the Tre1+ systems and a weak salt bridge or no salt bridge, using an alternative arginine, is likely in the Tre1sctt systems. CONCLUSIONS The weak salt bridge or lack of a salt bridge in the Tre1sctt systems could be one possible explanation for the disrupted function of Tre1sctt in primordial germ cell migration. These results provide a framework for studying the importance of the arginine of the D/E/NRY motif in the structure and function of other GPCRs that are involved in cell migration, such as CXCR4 in the mouse, zebrafish, and chicken.
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Affiliation(s)
- Margaret M Pruitt
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
| | - Monica H Lamm
- Department of Chemical and Biological Engineering, Iowa State University, Ames, IA 50011, USA
| | - Clark R Coffman
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
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30
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Moreira IS. Structural features of the G-protein/GPCR interactions. Biochim Biophys Acta Gen Subj 2013; 1840:16-33. [PMID: 24016604 DOI: 10.1016/j.bbagen.2013.08.027] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 08/27/2013] [Accepted: 08/28/2013] [Indexed: 01/07/2023]
Abstract
BACKGROUND The details of the functional interaction between G proteins and the G protein coupled receptors (GPCRs) have long been subjected to extensive investigations with structural and functional assays and a large number of computational studies. SCOPE OF REVIEW The nature and sites of interaction in the G-protein/GPCR complexes, and the specificities of these interactions selecting coupling partners among the large number of families of GPCRs and G protein forms, are still poorly defined. MAJOR CONCLUSIONS Many of the contact sites between the two proteins in specific complexes have been identified, but the three dimensional molecular architecture of a receptor-Gα interface is only known for one pair. Consequently, many fundamental questions regarding this macromolecular assembly and its mechanism remain unanswered. GENERAL SIGNIFICANCE In the context of current structural data we review the structural details of the interfaces and recognition sites in complexes of sub-family A GPCRs with cognate G-proteins, with special emphasis on the consequences of activation on GPCR structure, the prevalence of preassembled GPCR/G-protein complexes, the key structural determinants for selective coupling and the possible involvement of GPCR oligomerization in this process.
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Affiliation(s)
- Irina S Moreira
- REQUIMTE/Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre s/n, 4169-007 Porto, Portugal.
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31
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Preininger AM, Meiler J, Hamm HE. Conformational flexibility and structural dynamics in GPCR-mediated G protein activation: a perspective. J Mol Biol 2013; 425:2288-98. [PMID: 23602809 DOI: 10.1016/j.jmb.2013.04.011] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 04/08/2013] [Accepted: 04/10/2013] [Indexed: 12/16/2022]
Abstract
Structure and dynamics of G proteins and their cognate receptors, both alone and in complex, are becoming increasingly accessible to experimental techniques. Understanding the conformational changes and timelines that govern these changes can lead to new insights into the processes of ligand binding and associated G protein activation. Experimental systems may involve the use of, or otherwise stabilize, non-native environments. This can complicate our understanding of structural and dynamic features of processes such as the ionic lock, tryptophan toggle, and G protein flexibility. While elements in the receptor's transmembrane helices and the C-terminal α5 helix of Gα undergo well-defined structural changes, regions subject to conformational flexibility may be important in fine-tuning the interactions between activated receptors and G proteins. The pairing of computational and experimental approaches will continue to provide powerful tools to probe the conformation and dynamics of receptor-mediated G protein activation.
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Affiliation(s)
- Anita M Preininger
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232-6600, USA.
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32
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Dror RO, Dirks RM, Grossman JP, Xu H, Shaw DE. Biomolecular simulation: a computational microscope for molecular biology. Annu Rev Biophys 2013; 41:429-52. [PMID: 22577825 DOI: 10.1146/annurev-biophys-042910-155245] [Citation(s) in RCA: 723] [Impact Index Per Article: 65.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Molecular dynamics simulations capture the behavior of biological macromolecules in full atomic detail, but their computational demands, combined with the challenge of appropriately modeling the relevant physics, have historically restricted their length and accuracy. Dramatic recent improvements in achievable simulation speed and the underlying physical models have enabled atomic-level simulations on timescales as long as milliseconds that capture key biochemical processes such as protein folding, drug binding, membrane transport, and the conformational changes critical to protein function. Such simulation may serve as a computational microscope, revealing biomolecular mechanisms at spatial and temporal scales that are difficult to observe experimentally. We describe the rapidly evolving state of the art for atomic-level biomolecular simulation, illustrate the types of biological discoveries that can now be made through simulation, and discuss challenges motivating continued innovation in this field.
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Affiliation(s)
- Ron O Dror
- D. E. Shaw Research, New York, New York 10036, USA.
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33
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Full and partial agonists of thromboxane prostanoid receptor unveil fine tuning of receptor superactive conformation and G protein activation. PLoS One 2013; 8:e60475. [PMID: 23555978 PMCID: PMC3610872 DOI: 10.1371/journal.pone.0060475] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 02/26/2013] [Indexed: 01/14/2023] Open
Abstract
The intrahelical salt bridge between E/D3.49 and R3.50 within the E/DRY motif on helix 3 (H3) and the interhelical hydrogen bonding between the E/DRY and residues on H6 are thought to be critical in stabilizing the class A G protein-coupled receptors in their inactive state. Removal of these interactions is expected to generate constitutively active receptors. This study examines how neutralization of E3.49/6.30 in the thromboxane prostanoid (TP) receptor alters ligand binding, basal, and agonist-induced activity and investigates the molecular mechanisms of G protein activation. We demonstrate here that a panel of full and partial agonists showed an increase in affinity and potency for E129V and E240V mutants. Yet, even augmenting the sensitivity to detect constitutive activity (CA) with overexpression of the receptor or the G protein revealed resistance to an increase in basal activity, while retaining fully the ability to cause agonist-induced signaling. However, direct G protein activation measured through bioluminescence resonance energy transfer (BRET) indicates that these mutants more efficiently communicate and/or activate their cognate G proteins. These results suggest the existence of additional constrains governing the shift of TP receptor to its active state, together with an increase propensity of these mutants to agonist-induced signaling, corroborating their definition as superactive mutants. The particular nature of the TP receptor as somehow “resistant” to CA should be examined in the context of its pathophysiological role in the cardiovascular system. Evolutionary forces may have favored regulation mechanisms leading to low basal activity and selected against more highly active phenotypes.
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34
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Characterization of the dynamic events of GPCRs by automated computational simulations. Biochem Soc Trans 2013; 41:205-12. [DOI: 10.1042/bst20120287] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The recent advances in membrane protein crystallography have provided extremely valuable structural information of the superfamily of GPCRs (G-protein-coupled receptors). This has been particularly true for a few receptors whose structure was solved several times under different biochemical conditions. It follows that the mechanisms of receptor conformational equilibrium and related dynamic events can be explored by computational simulations. In the present article, we summarize our recent understanding of several dynamic features of GPCRs, accomplished through the use of MD (molecular dynamics) simulations. Our pipeline for the MD simulations of GPCRs, implemented in the web service http://gpcr.usc.es, is updated in the present paper and illustrated by recent applications. Special emphasis is put on the A2A adenosine receptor, one of the selected cases where crystal structures in several conformations and conditions exist, and on the dimerization process of the CXCR4 (CXC chemokine receptor 4).
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35
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Taddese B, Simpson LM, Wall ID, Blaney FE, Reynolds CA. Modeling Active GPCR Conformations. Methods Enzymol 2013; 522:21-35. [DOI: 10.1016/b978-0-12-407865-9.00002-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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36
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Isin B, Estiu G, Wiest O, Oltvai ZN. Identifying ligand binding conformations of the β2-adrenergic receptor by using its agonists as computational probes. PLoS One 2012; 7:e50186. [PMID: 23300522 PMCID: PMC3534076 DOI: 10.1371/journal.pone.0050186] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Accepted: 10/22/2012] [Indexed: 11/19/2022] Open
Abstract
Recently available G-protein coupled receptor (GPCR) structures and biophysical studies suggest that the difference between the effects of various agonists and antagonists cannot be explained by single structures alone, but rather that the conformational ensembles of the proteins need to be considered. Here we use an elastic network model-guided molecular dynamics simulation protocol to generate an ensemble of conformers of a prototypical GPCR, β(2)-adrenergic receptor (β(2)AR). The resulting conformers are clustered into groups based on the conformations of the ligand binding site, and distinct conformers from each group are assessed for their binding to known agonists of β(2)AR. We show that the select ligands bind preferentially to different predicted conformers of β(2)AR, and identify a role of β(2)AR extracellular region as an allosteric binding site for larger drugs such as salmeterol. Thus, drugs and ligands can be used as "computational probes" to systematically identify protein conformers with likely biological significance.
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Affiliation(s)
- Basak Isin
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Guillermina Estiu
- Department of Chemistry and Biochemistry and Center for Rare and Neglected Diseases, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Olaf Wiest
- Department of Chemistry and Biochemistry and Center for Rare and Neglected Diseases, University of Notre Dame, Notre Dame, Indiana, United States of America
- Laboratory of Computational Chemistry and Drug Design, Laboratory of Chemical Genomics, Peking University, Shenzhen Graduate School, Shenzhen, China
| | - Zoltán N. Oltvai
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
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37
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Collu F, Ceccarelli M, Ruggerone P. Exploring binding properties of agonists interacting with a δ-opioid receptor. PLoS One 2012; 7:e52633. [PMID: 23300729 PMCID: PMC3530460 DOI: 10.1371/journal.pone.0052633] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2011] [Accepted: 11/20/2012] [Indexed: 11/19/2022] Open
Abstract
Ligand-receptor interactions are at the basis of the mediation of our physiological responses to a large variety of ligands, such as hormones, neurotransmitters and environmental stimulants, and their tuning represents the goal of a large variety of therapies. Several molecular details of these interactions are still largely unknown. In an effort to shed some light on this important issue, we performed a computational study on the interaction of two related compounds differing by a single methyl group (clozapine and desmethylclozapine) with a -opioid receptor. According to experiments, desmethylclozapine is more active than clozapine, providing a system well suited for a comparative study. We investigated stable configurations of the two drugs inside the receptor by simulating their escape routes by molecular dynamics simulations. Our results point out that the action of the compounds might be related to the spatial and temporal distribution of the affinity sites they visit during their permanency. Moreover, no particularly pronounced structural perturbations of the receptor were detected during the simulations, reinforcing the idea of a strong dynamical character of the interaction process, with an important role played by the solvent in addition.
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Affiliation(s)
- Francesca Collu
- CNR-IOM SLACS and Dipartimento di Fisica, Università degli Studi di Cagliari, Monserrato, Italy
| | - Matteo Ceccarelli
- Dipartimento di Fisica, Università degli Studi di Cagliari, Monserrato, Italy
| | - Paolo Ruggerone
- Dipartimento di Fisica, Università degli Studi di Cagliari, Monserrato, Italy
- * E-mail:
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38
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Lee JY, Lyman E. Agonist dynamics and conformational selection during microsecond simulations of the A(2A) adenosine receptor. Biophys J 2012; 102:2114-20. [PMID: 22824275 DOI: 10.1016/j.bpj.2012.03.061] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Revised: 03/16/2012] [Accepted: 03/22/2012] [Indexed: 11/19/2022] Open
Abstract
The G-protein-coupled receptors (GPCRs) are a ubiquitous family of signaling proteins of exceptional pharmacological importance. The recent publication of structures of several GPCRs cocrystallized with ligands of differing activity offers a unique opportunity to gain insight into their function. To that end, we performed microsecond-timescale simulations of the A(2A) adenosine receptor bound to either of two agonists, adenosine or UK432097. Our data suggest that adenosine is highly dynamic when bound to A(2A), in stark contrast to the case with UK432097. Remarkably, adenosine finds an alternate binding pose in which the ligand is inverted relative to the crystal structure, forming relatively stable interactions with helices I and II. Our observations suggest new experimental tests to validate our predictions and deepen our understanding of GPCR signaling. Overall, our data suggest an intriguing hypothesis: that the 100- to 1000-fold greater efficacy of UK432097 relative to adenosine arises because UK432097 stabilizes a much tighter neighborhood of active conformations, which manifests as a greater likelihood of G-protein activation per unit time.
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Affiliation(s)
- Ji Young Lee
- Department of Physics and Astronomy, and Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, USA
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39
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Wang CIA, Lewis RJ. Emerging opportunities for allosteric modulation of G-protein coupled receptors. Biochem Pharmacol 2012; 85:153-62. [PMID: 22975406 DOI: 10.1016/j.bcp.2012.09.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Revised: 09/03/2012] [Accepted: 09/04/2012] [Indexed: 12/23/2022]
Abstract
Their ubiquitous nature, wide cellular distribution and versatile molecular recognition and signalling help make G-protein binding receptors (GPCRs) the most important class of membrane proteins in clinical medicine, accounting for ∼40% of all current therapeutics. A large percentage of current drugs target the endogenous ligand binding (orthosteric) site, which are structurally and evolutionarily conserved, particularly among members of the same GPCR subfamily. With the recent advances in GPCR X-ray crystallography, new opportunities for developing novel subtype selective drugs have emerged. Given the increasing recognition that the extracellular surface conformation changes in response to ligand binding, it is likely that all GPCRs possess an allosteric site(s) capable of regulating GPCR signalling. Allosteric sites are less structurally conserved than their corresponding orthosteric site and thus provide new opportunities for the development of more selective drugs. Constitutive oligomerisation (dimerisation) identified in many of the GPCRs investigated, adds another dimension to the structural and functional complexity of GPCRs. In this review, we compare 60 crystal structures of nine GPCR subtypes (rhodopsin, ß₂-AR, ß₁-AR, A(2a)-AR, CXCR4, D₃R, H₁R, M₂R, M₃R) across four subfamilies of Class A GPCRs, and discuss mechanisms involved in receptor activation and potential allosteric binding sites across the highly variable extracellular surface of these GPCRs. This analysis has identified a new extracellular salt bridge (ESB-2) that might be exploited in the design of allosteric modulators.
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Affiliation(s)
- Ching-I Anderson Wang
- Institute for Molecular Bioscience, University of Queensland, Brisbane, QLD 4072 Australia
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40
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Trzaskowski B, Latek D, Yuan S, Ghoshdastider U, Debinski A, Filipek S. Action of molecular switches in GPCRs--theoretical and experimental studies. Curr Med Chem 2012; 19:1090-109. [PMID: 22300046 PMCID: PMC3343417 DOI: 10.2174/092986712799320556] [Citation(s) in RCA: 336] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Revised: 12/30/2011] [Accepted: 01/02/2012] [Indexed: 01/14/2023]
Abstract
G protein coupled receptors (GPCRs), also called 7TM receptors, form a huge superfamily of membrane proteins that, upon activation by extracellular agonists, pass the signal to the cell interior. Ligands can bind either to extracellular N-terminus and loops (e.g. glutamate receptors) or to the binding site within transmembrane helices (Rhodopsin-like family). They are all activated by agonists although a spontaneous auto-activation of an empty receptor can also be observed. Biochemical and crystallographic methods together with molecular dynamics simulations and other theoretical techniques provided models of the receptor activation based on the action of so-called "molecular switches" buried in the receptor structure. They are changed by agonists but also by inverse agonists evoking an ensemble of activation states leading toward different activation pathways. Switches discovered so far include the ionic lock switch, the 3-7 lock switch, the tyrosine toggle switch linked with the nPxxy motif in TM7, and the transmission switch. The latter one was proposed instead of the tryptophan rotamer toggle switch because no change of the rotamer was observed in structures of activated receptors. The global toggle switch suggested earlier consisting of a vertical rigid motion of TM6, seems also to be implausible based on the recent crystal structures of GPCRs with agonists. Theoretical and experimental methods (crystallography, NMR, specific spectroscopic methods like FRET/BRET but also single-molecule-force-spectroscopy) are currently used to study the effect of ligands on the receptor structure, location of stable structural segments/domains of GPCRs, and to answer the still open question on how ligands are binding: either via ensemble of conformational receptor states or rather via induced fit mechanisms. On the other hand the structural investigations of homoand heterodimers and higher oligomers revealed the mechanism of allosteric signal transmission and receptor activation that could lead to design highly effective and selective allosteric or ago-allosteric drugs.
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Affiliation(s)
- B Trzaskowski
- Faculty of Chemistry, University of Warsaw, ul. Pasteura 1, 02-093 Warsaw, Poland
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41
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Salon JA, Lodowski DT, Palczewski K. The significance of G protein-coupled receptor crystallography for drug discovery. Pharmacol Rev 2012; 63:901-37. [PMID: 21969326 DOI: 10.1124/pr.110.003350] [Citation(s) in RCA: 160] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Crucial as molecular sensors for many vital physiological processes, seven-transmembrane domain G protein-coupled receptors (GPCRs) comprise the largest family of proteins targeted by drug discovery. Together with structures of the prototypical GPCR rhodopsin, solved structures of other liganded GPCRs promise to provide insights into the structural basis of the superfamily's biochemical functions and assist in the development of new therapeutic modalities and drugs. One of the greatest technical and theoretical challenges to elucidating and exploiting structure-function relationships in these systems is the emerging concept of GPCR conformational flexibility and its cause-effect relationship for receptor-receptor and receptor-effector interactions. Such conformational changes can be subtle and triggered by relatively small binding energy effects, leading to full or partial efficacy in the activation or inactivation of the receptor system at large. Pharmacological dogma generally dictates that these changes manifest themselves through kinetic modulation of the receptor's G protein partners. Atomic resolution information derived from increasingly available receptor structures provides an entrée to the understanding of these events and practically applying it to drug design. Supported by structure-activity relationship information arising from empirical screening, a unified structural model of GPCR activation/inactivation promises to both accelerate drug discovery in this field and improve our fundamental understanding of structure-based drug design in general. This review discusses fundamental problems that persist in drug design and GPCR structural determination.
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Affiliation(s)
- John A Salon
- Department of Molecular Structure, Amgen Incorporated, Thousand Oaks, California, USA
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42
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Leioatts N, Romo TD, Grossfield A. Elastic Network Models are Robust to Variations in Formalism. J Chem Theory Comput 2012; 8:2424-2434. [PMID: 22924033 DOI: 10.1021/ct3000316] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Understanding the functions of biomolecules requires insight not only from structures, but from dynamics as well. Often, the most interesting processes occur on time scales too slow for exploration by conventional molecular dynamics (MD) simulations. For this reason, alternative computational methods such as elastic network models (ENMs) have become increasingly popular. These simple, coarse-grained models represent molecules as beads connected by harmonic springs; the system's motions are solved analytically by normal mode analysis. In the past few years, many different formalisms for performing ENM calculations have emerged, and several have been optimized using all-atom MD simulations. In contrast to other studies, we have compared the various formalisms in a systematic, quantitative way. In this study, we optimize many ENM functional forms using a uniform dataset containing only long (> 1 μs) all-atom MD simulations. Our results show that all models once optimized produce spring constants for immediate neighboring residues that are orders of magnitude stiffer than more distal contacts. In addition, the statistical significance of ENM performance varied with model resolution. We also show that fitting long trajectories does not improve ENM performance due to a problem inherent in all network models tested: they underestimate the relative importance of the most concerted motions. Finally, we characterize ENMs' resilience by tessellating the parameter space to show that broad ranges of parameters produce similar quality predictions. Taken together our data reveals that choice of spring function and parameters are not vital to performance of a network model and that simple parameters can by derived "by hand" when no data is available for fitting, thus illustrating the robustness of these models.
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Affiliation(s)
- Nicholas Leioatts
- Department of Biochemistry & Biophysics, University of Rochester Medical Center, Rochester, NY 14642, USA
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43
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Ligand-dependent conformations and dynamics of the serotonin 5-HT(2A) receptor determine its activation and membrane-driven oligomerization properties. PLoS Comput Biol 2012; 8:e1002473. [PMID: 22532793 PMCID: PMC3330085 DOI: 10.1371/journal.pcbi.1002473] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Accepted: 02/26/2012] [Indexed: 11/19/2022] Open
Abstract
From computational simulations of a serotonin 2A receptor (5-HT2AR) model complexed with pharmacologically and structurally diverse ligands we identify different conformational states and dynamics adopted by the receptor bound to the full agonist 5-HT, the partial agonist LSD, and the inverse agonist Ketanserin. The results from the unbiased all-atom molecular dynamics (MD) simulations show that the three ligands affect differently the known GPCR activation elements including the toggle switch at W6.48, the changes in the ionic lock between E6.30 and R3.50 of the DRY motif in TM3, and the dynamics of the NPxxY motif in TM7. The computational results uncover a sequence of steps connecting these experimentally-identified elements of GPCR activation. The differences among the properties of the receptor molecule interacting with the ligands correlate with their distinct pharmacological properties. Combining these results with quantitative analysis of membrane deformation obtained with our new method (Mondal et al, Biophysical Journal 2011), we show that distinct conformational rearrangements produced by the three ligands also elicit different responses in the surrounding membrane. The differential reorganization of the receptor environment is reflected in (i)-the involvement of cholesterol in the activation of the 5-HT2AR, and (ii)-different extents and patterns of membrane deformations. These findings are discussed in the context of their likely functional consequences and a predicted mechanism of ligand-specific GPCR oligomerization. The 5-HT2A receptor for the neurotransmitter serotonin (5-HT) belongs to family A (rhodopsin-like) G-protein coupled receptors (GPCRs), one of the most important classes of membrane proteins that are targeted by an extensive and diverse collection of external stimuli. Recently we learned that different ligands targeting the same GPCR can elicit different biological responses, but the mechanisms remain unknown. We address this fundamental question for the serotonin 5-HT2A receptor, because it is known to respond to the binding of structurally diverse ligands by producing similar stimuli in the cell, and to the binding of quite similar ligands with dramatically different responses. Molecular dynamics simulations of molecular models of the serotonin 5-HT2A receptor in complex with pharmacologically distinct ligands show the dynamic rearrangements of the receptor molecule to be different for these ligands, and the nature and extents of the rearrangements reflect the known pharmacological properties of the ligands as full, partial or inverse activators of the receptor. The different rearrangements of the receptor molecule are shown to produce different rearrangements of the surrounding membrane, a remodeling of the environment that can have differential ligand-determined effects on receptor function and association in the cell's membrane.
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44
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Isin B, Tirupula KC, Oltvai ZN, Klein-Seetharaman J, Bahar I. Identification of motions in membrane proteins by elastic network models and their experimental validation. Methods Mol Biol 2012; 914:285-317. [PMID: 22976035 DOI: 10.1007/978-1-62703-023-6_17] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Identifying the functional motions of membrane proteins is difficult because they range from large-scale collective dynamics to local small atomic fluctuations at different timescales that are difficult to measure experimentally due to the hydrophobic nature of these proteins. Elastic Network Models, and in particular their most widely used implementation, the Anisotropic Network Model (ANM), have proven to be useful computational methods in many recent applications to predict membrane protein dynamics. These models are based on the premise that biomolecules possess intrinsic mechanical characteristics uniquely defined by their particular architectures. In the ANM, interactions between residues in close proximity are represented by harmonic potentials with a uniform spring constant. The slow mode shapes generated by the ANM provide valuable information on the global dynamics of biomolecules that are relevant to their function. In its recent extension in the form of ANM-guided molecular dynamics (MD), this coarse-grained approach is augmented with atomic detail. The results from ANM and its extensions can be used to guide experiments and thus speedup the process of quantifying motions in membrane proteins. Testing the predictions can be accomplished through (a) direct observation of motions through studies of structure and biophysical probes, (b) perturbation of the motions by, e.g., cross-linking or site-directed mutagenesis, and (c) by studying the effects of such perturbations on protein function, typically through ligand binding and activity assays. To illustrate the applicability of the combined computational ANM-experimental testing framework to membrane proteins, we describe-alongside the general protocols-here the application of ANM to rhodopsin, a prototypical member of the pharmacologically relevant G-protein coupled receptor family.
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Affiliation(s)
- Basak Isin
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
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Fanelli F, De Benedetti PG. Update 1 of: computational modeling approaches to structure-function analysis of G protein-coupled receptors. Chem Rev 2011; 111:PR438-535. [PMID: 22165845 DOI: 10.1021/cr100437t] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Francesca Fanelli
- Dulbecco Telethon Institute, University of Modena and Reggio Emilia, via Campi 183, 41125 Modena, Italy.
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46
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Ghosh A, Sonavane U, Andhirka SK, Aradhyam GK, Joshi R. Structural insights into human GPCR protein OA1: a computational perspective. J Mol Model 2011; 18:2117-33. [DOI: 10.1007/s00894-011-1228-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Accepted: 08/18/2011] [Indexed: 11/24/2022]
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Johnston JM, Filizola M. Showcasing modern molecular dynamics simulations of membrane proteins through G protein-coupled receptors. Curr Opin Struct Biol 2011; 21:552-8. [PMID: 21764295 DOI: 10.1016/j.sbi.2011.06.008] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Revised: 06/06/2011] [Accepted: 06/21/2011] [Indexed: 12/30/2022]
Abstract
Despite many years of dedicated efforts, high-resolution structural determination of membrane proteins lags far behind that of soluble proteins. Computational methods in general, and molecular dynamics (MD) simulations in particular, have represented important alternative resources over the years to advance understanding of membrane protein structure and function. However, it is only recently that much progress has been achieved owing to new high-resolution membrane protein structures, specialized parallel computer architectures, and efficient simulation algorithms. This has definitely been the case for G protein-coupled receptors (GPCRs), which have assumed a leading role in the area of structural biology with several new structures appearing in the literature during the past five years. We provide here a concise overview of recent developments in computational biophysics of membrane proteins, using GPCRs as an example to showcase important information that can be derived from modern MD simulations.
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Affiliation(s)
- Jennifer M Johnston
- Department of Structural and Chemical Biology, Mount Sinai School of Medicine, 1425 Madison Avenue, Box 1677, New York, NY 10029, USA
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Grossfield A. Recent progress in the study of G protein-coupled receptors with molecular dynamics computer simulations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:1868-78. [DOI: 10.1016/j.bbamem.2011.03.010] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Revised: 02/23/2011] [Accepted: 03/21/2011] [Indexed: 01/28/2023]
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49
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Romo TD, Grossfield A. Block Covariance Overlap Method and Convergence in Molecular Dynamics Simulation. J Chem Theory Comput 2011; 7:2464-72. [DOI: 10.1021/ct2002754] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tod D. Romo
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, New York 14642, United States
| | - Alan Grossfield
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, New York 14642, United States
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Rodríguez D, Piñeiro Á, Gutiérrez-de-Terán H. Molecular Dynamics Simulations Reveal Insights into Key Structural Elements of Adenosine Receptors. Biochemistry 2011; 50:4194-208. [DOI: 10.1021/bi200100t] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- David Rodríguez
- Fundación Pública Galega de Medicina Xenómica, Hospital Clínico Universitario de Santiago (CHUS), planta-2, A Choupana, s/n E-15706 Santiago de Compostela, Spain
| | - Ángel Piñeiro
- Soft Matter and Molecular Biophysics Group, Department of Applied Physics, University of Santiago de Compostela, Campus Vida s/n, E-15782 Santiago de Compostela, Spain
| | - Hugo Gutiérrez-de-Terán
- Fundación Pública Galega de Medicina Xenómica, Hospital Clínico Universitario de Santiago (CHUS), planta-2, A Choupana, s/n E-15706 Santiago de Compostela, Spain
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