1
|
Poria D, Kolesnikov AV, Lee TJ, Salom D, Palczewski K, Kefalov VJ. Investigating the Role of Rhodopsin F45L Mutation in Mouse Rod Photoreceptor Signaling and Survival. eNeuro 2023; 10:ENEURO.0330-22.2023. [PMID: 36823167 PMCID: PMC9997694 DOI: 10.1523/eneuro.0330-22.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 01/16/2023] [Accepted: 01/24/2023] [Indexed: 02/25/2023] Open
Abstract
Rhodopsin is the critical receptor molecule which enables vertebrate rod photoreceptor cells to detect a single photon of light and initiate a cascade of molecular events leading to visual perception. Recently, it has been suggested that the F45L mutation in the transmembrane helix of rhodopsin disrupts its dimerization in vitro To determine whether this mutation of rhodopsin affects its signaling properties in vivo, we generated knock-in mice expressing the rhodopsin F45L mutant. We then examined the function of rods in the mutant mice versus wild-type controls, using in vivo electroretinography and transretinal and single cell suction recordings, combined with morphologic analysis and spectrophotometry. Although we did not evaluate the effect of the F45L mutation on the state of dimerization of the rhodopsin in vivo, our results revealed that F45L-mutant mice exhibit normal retinal morphology, normal rod responses as measured both in vivo and ex vivo, and normal rod dark adaptation. We conclude that the F45L mutation does not affect the signaling properties of rhodopsin in its natural setting.
Collapse
Affiliation(s)
- Deepak Poria
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, CA 92697
| | - Alexander V Kolesnikov
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, CA 92697
| | - Tae Jun Lee
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, MO 63110
| | - David Salom
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, CA 92697
| | - Krzysztof Palczewski
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, CA 92697
- Department of Chemistry, University of California, Irvine, CA 92697
- Department of Physiology and Biophysics, University of California, Irvine, CA 92697
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697
| | - Vladimir J Kefalov
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, CA 92697
- Department of Physiology and Biophysics, University of California, Irvine, CA 92697
| |
Collapse
|
2
|
Lobo GP, Radhakrishnan R, Leung M, Gruesen A, Knölker HJ, van Kuijk FJ, Montezuma SR. In Silico Prediction of MYO1C-Rhodopsin Interactions and Its Significance in Protein Localization and Visual Function. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1415:499-505. [PMID: 37440078 DOI: 10.1007/978-3-031-27681-1_73] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/14/2023]
Abstract
Rods and cones are photoreceptor neurons in the retina that are required for visual sensation in vertebrates, where proper protein localization and compartmentalization are critical for phototransduction and visual function. In human retinal diseases, improper protein transport to the outer segment (OS) or mislocalization of proteins to the inner segment (IS) could lead to impaired visual responses and photoreceptor cell degeneration, causing a loss of visual function. We showed involvement of an unconventional motor protein, MYO1C, in the proper localization of rhodopsin to the OS, where loss of MYO1C in a mammalian model caused mislocalization of rhodopsin to IS and cell bodies, leading to progressively severe retinal phenotypes. In this study, using modeling and docking analysis, we aimed to identify the protein-protein interaction sites between MYO1C and Rhodopsin to establish a hypothesis that a physical interaction between these proteins is necessary for the proper trafficking of rhodopsin and visual function.
Collapse
Affiliation(s)
- Glenn P Lobo
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN, USA.
| | - Rakesh Radhakrishnan
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN, USA
| | - Matthias Leung
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN, USA
| | - Andrew Gruesen
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN, USA
| | | | - Frederik J van Kuijk
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN, USA
| | - Sandra R Montezuma
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN, USA
| |
Collapse
|
3
|
Ortega JT, McKee AG, Roushar FJ, Penn WD, Schlebach JP, Jastrzebska B. Chromenone derivatives as novel pharmacological chaperones for retinitis pigmentosa-linked rod opsin mutants. Hum Mol Genet 2022; 31:3439-3457. [PMID: 35642742 PMCID: PMC9558842 DOI: 10.1093/hmg/ddac125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 05/23/2022] [Accepted: 05/24/2022] [Indexed: 11/14/2022] Open
Abstract
The correct expression of folded, functional rhodopsin (Rho) is critical for visual perception. However, this seven-transmembrane helical G protein-coupled receptor is prone to mutations with pathological consequences of retinal degeneration in retinitis pigmentosa (RP) due to Rho misfolding. Pharmacological chaperones that stabilize the inherited Rho variants by assisting their folding and membrane targeting could slow the progression of RP. In this study, we employed virtual screening of synthetic compounds with a natural product scaffold in conjunction with in vitro and in vivo evaluations to discover a novel chromenone-containing small molecule with favorable pharmacological properties that stabilize rod opsin. This compound reversibly binds to unliganded bovine rod opsin with an EC50 value comparable to the 9-cis-retinal chromophore analog and partially rescued membrane trafficking of multiple RP-related rod opsin variants in vitro. Importantly, this novel ligand of rod opsin was effective in vivo in murine models, protecting photoreceptors from deterioration caused by either bright light or genetic insult. Together, our current study suggests potential broad therapeutic implications of the new chromenone-containing non-retinoid small molecule against retinal diseases associated with photoreceptor degeneration.
Collapse
Affiliation(s)
- Joseph T Ortega
- Department of Pharmacology and Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Andrew G McKee
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, IN 47405-7102, USA
| | - Francis J Roushar
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, IN 47405-7102, USA
| | - Wesley D Penn
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, IN 47405-7102, USA
| | - Jonathan P Schlebach
- To whom correspondence should be addressed at: Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 441064965, USA. Tel: +1 2163685683; Fax: +1 2163681300; (Beata Jastrzebska); Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, IN 47405-7102, USA. Tel: +1 812-855-6779; Fax: +1 812-855-8300; (Jonathan P. Schlebach)
| | - Beata Jastrzebska
- To whom correspondence should be addressed at: Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 441064965, USA. Tel: +1 2163685683; Fax: +1 2163681300; (Beata Jastrzebska); Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, IN 47405-7102, USA. Tel: +1 812-855-6779; Fax: +1 812-855-8300; (Jonathan P. Schlebach)
| |
Collapse
|
4
|
Kennedy A, Ren HY, Madden VJ, Cyr DM. Lysosome docking to WIPI1 rings and ER-connected phagophores occurs during DNAJB12- and GABARAP-dependent selective autophagy of misfolded P23H-rhodopsin. Mol Biol Cell 2022; 33:ar84. [PMID: 35704470 PMCID: PMC9582645 DOI: 10.1091/mbc.e21-10-0505] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
We report on how the endoplasmic reticulum (ER)-associated-autophagy pathway (ERAA) delivers P23H-rhodopsin (P23H-R) to the lysosome. P23H-R accumulates in an ERAD-resistant conformation that is stabilized in a detergent-soluble state by DNAJB12 and Hsp70. P23H-R, DNAJB12, and FIP200 colocalize in discrete foci that punctuate the rim of omegasome rings coated by WIPI1. Loss of DNAJB12 function prevents the association of P23H-R containing ER tubules with omegasomes. P23H-R tubules thread through the wall of WIPI1 rings into their central cavity. Transfer of P23H-R from ER-connected phagophores to lysosomes requires GABARAP and is associated with the transient docking of lysosomes to WIPI1 rings. After departure from WIPI1 rings, new patches of P23H-R are seen in the membranes of lysosomes. The absence of GABARAP prevents transfer of P23H-R from phagophores to lysosomes without interfering with docking. These data identify lysosome docking to omegasomes as an important step in the DNAJB12- and GABARAP-dependent autophagic disposal of dominantly toxic P23H-R.
Collapse
Affiliation(s)
- Andrew Kennedy
- Department of Cell Biology and Physiology, School of Medicine, and
| | - Hong Yu Ren
- Department of Cell Biology and Physiology, School of Medicine, and
| | - Victoria J. Madden
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Douglas M. Cyr
- Department of Cell Biology and Physiology, School of Medicine, and,*Address correspondence to: Douglas M. Cyr ()
| |
Collapse
|
5
|
Radhakrishnan R, Dronamraju VR, Leung M, Gruesen A, Solanki AK, Walterhouse S, Roehrich H, Song G, da Costa Monsanto R, Cureoglu S, Martin R, Kondkar AA, van Kuijk FJ, Montezuma SR, Knöelker HJ, Hufnagel RB, Lobo GP. The role of motor proteins in photoreceptor protein transport and visual function. Ophthalmic Genet 2022; 43:285-300. [PMID: 35470760 DOI: 10.1080/13816810.2022.2062391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
BACKGROUND Rods and cones are photoreceptor neurons in the retina that are required for visual sensation in vertebrates, wherein the perception of vision is initiated when these neurons respond to photons in the light stimuli. The photoreceptor cell is structurally studied as outer segments (OS) and inner segments (IS) where proper protein sorting, localization, and compartmentalization are critical for phototransduction, visual function, and survival. In human retinal diseases, improper protein transport to the OS or mislocalization of proteins to the IS and other cellular compartments could lead to impaired visual responses and photoreceptor cell degeneration that ultimately cause loss of visual function. RESULTS Therefore, studying and identifying mechanisms involved in facilitating and maintaining proper protein transport in photoreceptor cells would help our understanding of pathologies involving retinal cell degeneration in inherited retinal dystrophies, age-related macular degeneration, and Usher Syndrome. CONCLUSIONS Our mini-review will discuss mechanisms of protein transport within photoreceptors and introduce a novel role for an unconventional motor protein, MYO1C, in actin-based motor transport of the visual chromophore Rhodopsin to the OS, in support of phototransduction and visual function.
Collapse
Affiliation(s)
- Rakesh Radhakrishnan
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, USA
| | - Venkateshwara R Dronamraju
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, USA
| | - Matthias Leung
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, USA
| | - Andrew Gruesen
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, USA
| | - Ashish K Solanki
- Department of Medicine, Drug Discovery Building, Medical University of South Carolina, South Carolina, USA
| | - Stephen Walterhouse
- Department of Medicine, Drug Discovery Building, Medical University of South Carolina, South Carolina, USA
| | - Heidi Roehrich
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, USA
| | - Grace Song
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, USA
| | - Rafael da Costa Monsanto
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, USA
| | - Sebahattin Cureoglu
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, USA
| | - René Martin
- Faculty of Chemistry, Technische Universität Dresden, Dresden, Germany
| | - Altaf A Kondkar
- Department of Ophthalmology.,Glaucoma Research Chair in Ophthalmology, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Frederik J van Kuijk
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, USA
| | - Sandra R Montezuma
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, USA
| | | | - Robert B Hufnagel
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Glenn P Lobo
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, USA.,Department of Medicine, Drug Discovery Building, Medical University of South Carolina, South Carolina, USA.,Department of Ophthalmology, Medical University of South Carolina, South Carolina, USA
| |
Collapse
|
6
|
Capturing a rhodopsin receptor signalling cascade across a native membrane. Nature 2022; 604:384-390. [PMID: 35388214 PMCID: PMC9007743 DOI: 10.1038/s41586-022-04547-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 02/14/2022] [Indexed: 11/12/2022]
Abstract
G protein-coupled receptors (GPCRs) are cell-surface receptors that respond to various stimuli to induce signalling pathways across cell membranes. Recent progress has yielded atomic structures of key intermediates1,2 and roles for lipids in signalling3,4. However, capturing signalling events of a wild-type receptor in real time, across a native membrane to its downstream effectors, has remained elusive. Here we probe the archetypal class A GPCR, rhodopsin, directly from fragments of native disc membranes using mass spectrometry. We monitor real-time photoconversion of dark-adapted rhodopsin to opsin, delineating retinal isomerization and hydrolysis steps, and further showing that the reaction is significantly slower in its native membrane than in detergent micelles. Considering the lipids ejected with rhodopsin, we demonstrate that opsin can be regenerated in membranes through photoisomerized retinal–lipid conjugates, and we provide evidence for increased association of rhodopsin with unsaturated long-chain phosphatidylcholine during signalling. Capturing the secondary steps of the signalling cascade, we monitor light activation of transducin (Gt) through loss of GDP to generate an intermediate apo-trimeric G protein, and observe Gαt•GTP subunits interacting with PDE6 to hydrolyse cyclic GMP. We also show how rhodopsin-targeting compounds either stimulate or dampen signalling through rhodopsin–opsin and transducin signalling pathways. Our results not only reveal the effect of native lipids on rhodopsin signalling and regeneration but also enable us to propose a paradigm for GPCR drug discovery in native membrane environments. The rhodopsin signalling cascade, initiated by light, is captured using mass spectrometry of a native membrane.
Collapse
|
7
|
Ortega JT, Jastrzebska B. Rhodopsin as a Molecular Target to Mitigate Retinitis Pigmentosa. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1371:61-77. [PMID: 34962636 DOI: 10.1007/5584_2021_682] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Retinitis pigmentosa (RP) is a group of hereditary degenerative diseases affecting 1 of 4000 people worldwide and being the most prevalent cause of visual handicap among working populations in developed countries. These disorders are mainly related to the abnormalities in the rod G protein-coupled receptor (GPCR), rhodopsin reflected in the dysregulated membrane trafficking, stability and phototransduction processes that lead to progressive loss of retina function and eventually blindness. Currently, there is no cure for RP, and the therapeutic options are limited. Targeting rhodopsin with small molecule chaperones to improve the folding and stability of the mutant receptor is one of the most promising pharmacological approaches to alleviate the pathology of RP. This review provides an update on the current knowledge regarding small molecule compounds that have been evaluated as rhodopsin modulators to be considered as leads for the development of novel therapies for RP.
Collapse
Affiliation(s)
- Joseph T Ortega
- Department of Pharmacology, School of Medicine, Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, Cleveland, OH, USA
| | - Beata Jastrzebska
- Department of Pharmacology, School of Medicine, Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, Cleveland, OH, USA.
| |
Collapse
|
8
|
Felline A, Schiroli D, Comitato A, Marigo V, Fanelli F. Structure network-based landscape of rhodopsin misfolding by mutations and algorithmic prediction of small chaperone action. Comput Struct Biotechnol J 2021; 19:6020-6038. [PMID: 34849206 PMCID: PMC8605067 DOI: 10.1016/j.csbj.2021.10.040] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 10/09/2021] [Accepted: 10/31/2021] [Indexed: 11/28/2022] Open
Abstract
Failure of a protein to achieve its functional structural state and normal cellular location contributes to the etiology and pathology of heritable human conformational diseases. The autosomal dominant form of retinitis pigmentosa (adRP) is an incurable blindness largely linked to mutations of the membrane protein rod opsin. While the mechanisms underlying the noxious effects of the mutated protein are not completely understood, a common feature is the functional protein conformational loss. Here, the wild type and 39 adRP rod opsin mutants were subjected to mechanical unfolding simulations coupled to the graph theory-based protein structure network analysis. A robust computational model was inferred and in vitro validated in its ability to predict endoplasmic reticulum retention of adRP mutants, a feature linked to the mutation-caused misfolding. The structure-based approach could also infer the structural determinants of small chaperone action on misfolded protein mutants with therapeutic implications. The approach is exportable to conformational diseases linked to missense mutations in any membrane protein.
Collapse
Affiliation(s)
- Angelo Felline
- Department of Life Sciences, University of Modena and Reggio Emilia, via Campi 103, 41125 Modena, Italy
| | - Davide Schiroli
- Department of Life Sciences, University of Modena and Reggio Emilia, via Campi 287, 41125 Modena, Italy
| | - Antonella Comitato
- Department of Life Sciences, University of Modena and Reggio Emilia, via Campi 287, 41125 Modena, Italy
| | - Valeria Marigo
- Department of Life Sciences, University of Modena and Reggio Emilia, via Campi 287, 41125 Modena, Italy.,Center for Neuroscience and Neurotechnology, Italy
| | - Francesca Fanelli
- Department of Life Sciences, University of Modena and Reggio Emilia, via Campi 103, 41125 Modena, Italy.,Center for Neuroscience and Neurotechnology, Italy
| |
Collapse
|
9
|
Fanelli F, Felline A, Marigo V. Structural aspects of rod opsin and their implication in genetic diseases. Pflugers Arch 2021; 473:1339-1359. [PMID: 33728518 DOI: 10.1007/s00424-021-02546-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2021] [Revised: 02/17/2021] [Accepted: 02/22/2021] [Indexed: 01/04/2023]
Abstract
Vision in dim-light conditions is triggered by photoactivation of rhodopsin, the visual pigment of rod photoreceptor cells. Rhodopsin is made of a protein, the G protein coupled receptor (GPCR) opsin, and the chromophore 11-cis-retinal. Vertebrate rod opsin is the GPCR best characterized at the atomic level of detail. Since the release of the first crystal structure 20 years ago, a huge number of structures have been released that, in combination with valuable spectroscopic determinations, unveiled most aspects of the photobleaching process. A number of spontaneous mutations of rod opsin have been found linked to vision-impairing diseases like autosomal dominant or autosomal recessive retinitis pigmentosa (adRP or arRP, respectively) and autosomal congenital stationary night blindness (adCSNB). While adCSNB is mainly caused by constitutive activation of rod opsin, RP shows more variegate determinants affecting different aspects of rod opsin function. The vast majority of missense rod opsin mutations affects folding and trafficking and is linked to adRP, an incurable disease that awaits light on its molecular structure determinants. This review article summarizes all major structural information available on vertebrate rod opsin conformational states and the insights gained so far into the structural determinants of adCSNB and adRP linked to rod opsin mutations. Strategies to design small chaperones with therapeutic potential for selected adRP rod opsin mutants will be discussed as well.
Collapse
Affiliation(s)
- Francesca Fanelli
- Department of Life Sciences, University of Modena and Reggio Emilia, via Campi 103, 41125, Modena, Italy. .,Center for Neuroscience and Neurotechnology, University of Modena and Reggio Emilia, via Campi 287, Modena, 41125, Italy.
| | - Angelo Felline
- Department of Life Sciences, University of Modena and Reggio Emilia, via Campi 103, 41125, Modena, Italy
| | - Valeria Marigo
- Center for Neuroscience and Neurotechnology, University of Modena and Reggio Emilia, via Campi 287, Modena, 41125, Italy.,Department of Life Sciences, University of Modena and Reggio Emilia, via Campi 287, 41125, Modena, Italy
| |
Collapse
|
10
|
Park PSH. Supramolecular organization of rhodopsin in rod photoreceptor cell membranes. Pflugers Arch 2021; 473:1361-1376. [PMID: 33591421 DOI: 10.1007/s00424-021-02522-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 01/12/2021] [Accepted: 01/18/2021] [Indexed: 11/30/2022]
Abstract
Rhodopsin is the light receptor in rod photoreceptor cells that initiates scotopic vision. Studies on the light receptor span well over a century, yet questions about the organization of rhodopsin within the photoreceptor cell membrane still persist and a consensus view on the topic is still elusive. Rhodopsin has been intensely studied for quite some time, and there is a wealth of information to draw from to formulate an organizational picture of the receptor in native membranes. Early experimental evidence in apparent support for a monomeric arrangement of rhodopsin in rod photoreceptor cell membranes is contrasted and reconciled with more recent visual evidence in support of a supramolecular organization of rhodopsin. What is known so far about the determinants of forming a supramolecular structure and possible functional roles for such an organization are also discussed. Many details are still missing on the structural and functional properties of the supramolecular organization of rhodopsin in rod photoreceptor cell membranes. The emerging picture presented here can serve as a springboard towards a more in-depth understanding of the topic.
Collapse
Affiliation(s)
- Paul S-H Park
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH, 44106, USA.
| |
Collapse
|
11
|
The Retinoid and Non-Retinoid Ligands of the Rod Visual G Protein-Coupled Receptor. Int J Mol Sci 2019; 20:ijms20246218. [PMID: 31835521 PMCID: PMC6941084 DOI: 10.3390/ijms20246218] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 11/27/2019] [Accepted: 12/06/2019] [Indexed: 02/06/2023] Open
Abstract
G protein-coupled receptors (GPCRs) play a predominant role in the drug discovery effort. These cell surface receptors are activated by a variety of specific ligands that bind to the orthosteric binding pocket located in the extracellular part of the receptor. In addition, the potential binding sites located on the surface of the receptor enable their allosteric modulation with critical consequences for their function and pharmacology. For decades, drug discovery focused on targeting the GPCR orthosteric binding sites. However, finding that GPCRs can be modulated allosterically opened a new venue for developing novel pharmacological modulators with higher specificity. Alternatively, focus on discovering of non-retinoid small molecules beneficial in retinopathies associated with mutations in rhodopsin is currently a fast-growing pharmacological field. In this review, we summarize the accumulated knowledge on retinoid ligands and non-retinoid modulators of the light-sensing GPCR, rhodopsin and their potential in combating the specific vision-related pathologies. Also, recent findings reporting the potential of biologically active compounds derived from natural products as potent rod opsin modulators with beneficial effects against degenerative diseases related to this receptor are highlighted here.
Collapse
|
12
|
Li Y, Wang M, Gao N, Li D, Lin J. The effect of dimerization on the activation and conformational dynamics of adenosine A 1 receptor. Phys Chem Chem Phys 2019; 21:22763-22773. [PMID: 31595279 DOI: 10.1039/c9cp04060a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The adenosine A1 receptor (A1R) is one of four adenosine receptors in humans, which are involved in the function of the cardiovascular, respiratory and central nervous systems. Experimental results indicate that A1R can form a homodimer and that the protomer-protomer interaction in the A1R dimer is related to certain pharmacological characteristics of A1R activation. In this work, we performed docking, metadynamics simulation, conventional molecular dynamics simulations, Gaussian-accelerated molecular dynamics simulations, potential of mean force calculations, dynamic cross-correlation motions analysis and community network analysis to study the binding mode of 5'-N-ethylcarboxamidoadenosine (NECA) to A1R and the effect of dimerization on the activation of A1R. Our results show that NECA binds to A1R in a similar mode to adenosine in the A1R crystal structure and NECA in the A2AR crystal structure. The A1R homodimer can be activated by one or two agonists with NECA occupying its orthosteric pockets in one (which we call the NECA-A1R system) or both protomers (which we call the dNECA-A1R system). In the NECA-A1R system, activation is predicated in the protomer without NECA bound. In the dNECA-A1R system, only one protomer achieves the active state. These findings suggest an asymmetrical activation mechanism of the homodimer and a negative cooperativity between the two protomers. We envision that our results may further facilitate the drug development of A1R.
Collapse
Affiliation(s)
- Yang Li
- State Key Laboratory of Medicinal Chemical Biology, College of Pharmacy and Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Haihe Education Park, 38 Tongyan Road, Tianjin 300353, People's Republic of China.
| | | | | | | | | |
Collapse
|
13
|
Single Proteoliposome High-Content Analysis Reveals Differences in the Homo-Oligomerization of GPCRs. Biophys J 2019; 115:300-312. [PMID: 30021106 DOI: 10.1016/j.bpj.2018.05.036] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 05/28/2018] [Accepted: 05/31/2018] [Indexed: 11/23/2022] Open
Abstract
G-protein-coupled receptors (GPCRs) control vital cellular signaling pathways. GPCR oligomerization is proposed to increase signaling diversity. However, many reports have arrived at disparate conclusions regarding the existence, stability, and stoichiometry of GPCR oligomers, partly because of cellular complexity and ensemble averaging of intrareconstitution heterogeneities that complicate the interpretation of oligomerization data. To overcome these limitations, we exploited fluorescence-microscopy-based high-content analysis of single proteoliposomes. This allowed multidimensional quantification of intrinsic monomer-monomer interactions of three class A GPCRs (β2-adrenergic receptor, cannabinoid receptor type 1, and opsin). Using a billion-fold less protein than conventional assays, we quantified oligomer stoichiometries, association constants, and the influence of two ligands and membrane curvature on oligomerization, revealing key similarities and differences for three GPCRs with decidedly different physiological functions. The assays introduced here will assist with the quantitative experimental observation of oligomerization for transmembrane proteins in general.
Collapse
|
14
|
Zhao DY, Pöge M, Morizumi T, Gulati S, Van Eps N, Zhang J, Miszta P, Filipek S, Mahamid J, Plitzko JM, Baumeister W, Ernst OP, Palczewski K. Cryo-EM structure of the native rhodopsin dimer in nanodiscs. J Biol Chem 2019; 294:14215-14230. [PMID: 31399513 DOI: 10.1074/jbc.ra119.010089] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2019] [Revised: 08/02/2019] [Indexed: 02/03/2023] Open
Abstract
Imaging of rod photoreceptor outer-segment disc membranes by atomic force microscopy and cryo-electron tomography has revealed that the visual pigment rhodopsin, a prototypical class A G protein-coupled receptor (GPCR), can organize as rows of dimers. GPCR dimerization and oligomerization offer possibilities for allosteric regulation of GPCR activity, but the detailed structures and mechanism remain elusive. In this investigation, we made use of the high rhodopsin density in the native disc membranes and of a bifunctional cross-linker that preserves the native rhodopsin arrangement by covalently tethering rhodopsins via Lys residue side chains. We purified cross-linked rhodopsin dimers and reconstituted them into nanodiscs for cryo-EM analysis. We present cryo-EM structures of the cross-linked rhodopsin dimer as well as a rhodopsin dimer reconstituted into nanodiscs from purified monomers. We demonstrate the presence of a preferential 2-fold symmetrical dimerization interface mediated by transmembrane helix 1 and the cytoplasmic helix 8 of rhodopsin. We confirmed this dimer interface by double electron-electron resonance measurements of spin-labeled rhodopsin. We propose that this interface and the arrangement of two protomers is a prerequisite for the formation of the observed rows of dimers. We anticipate that the approach outlined here could be extended to other GPCRs or membrane receptors to better understand specific receptor dimerization mechanisms.
Collapse
Affiliation(s)
- Dorothy Yanling Zhao
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Matthias Pöge
- Department of Molecular Structural Biology, Max-Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Takefumi Morizumi
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Sahil Gulati
- Gavin Herbert Eye Institute and the Department of Ophthalmology, University of California, Irvine, California 92697.,Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106
| | - Ned Van Eps
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Jianye Zhang
- Gavin Herbert Eye Institute and the Department of Ophthalmology, University of California, Irvine, California 92697.,Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106
| | - Przemyslaw Miszta
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Warsaw 02-093, Poland
| | - Slawomir Filipek
- Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Warsaw 02-093, Poland
| | - Julia Mahamid
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Jürgen M Plitzko
- Department of Molecular Structural Biology, Max-Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Wolfgang Baumeister
- Department of Molecular Structural Biology, Max-Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Oliver P Ernst
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada .,Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Krzysztof Palczewski
- Gavin Herbert Eye Institute and the Department of Ophthalmology, University of California, Irvine, California 92697 .,Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106
| |
Collapse
|
15
|
Chen G, Luo Y, Warncke K, Sun Y, Yu DS, Fu H, Behera M, Ramalingam SS, Doetsch PW, Duong DM, Lammers M, Curran WJ, Deng X. Acetylation regulates ribonucleotide reductase activity and cancer cell growth. Nat Commun 2019; 10:3213. [PMID: 31324785 PMCID: PMC6642173 DOI: 10.1038/s41467-019-11214-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 06/25/2019] [Indexed: 12/26/2022] Open
Abstract
Ribonucleotide reductase (RNR) catalyzes the de novo synthesis of deoxyribonucleoside diphosphates (dNDPs) to provide dNTP precursors for DNA synthesis. Here, we report that acetylation and deacetylation of the RRM2 subunit of RNR acts as a molecular switch that impacts RNR activity, dNTP synthesis, and DNA replication fork progression. Acetylation of RRM2 at K95 abrogates RNR activity by disrupting its homodimer assembly. RRM2 is directly acetylated by KAT7, and deacetylated by Sirt2, respectively. Sirt2, which level peak in S phase, sustains RNR activity at or above a threshold level required for dNTPs synthesis. We also find that radiation or camptothecin-induced DNA damage promotes RRM2 deacetylation by enhancing Sirt2-RRM2 interaction. Acetylation of RRM2 at K95 results in the reduction of the dNTP pool, DNA replication fork stalling, and the suppression of tumor cell growth in vitro and in vivo. This study therefore identifies acetylation as a regulatory mechanism governing RNR activity.
Collapse
Affiliation(s)
- Guo Chen
- Departments of Radiation Oncology, Emory University School of Medicine and Winship Cancer Institute of Emory University, 1365C Clifton Road NE, Atlanta, GA, 30322, USA
- Department of Medical Biochemistry and Molecular Biology, School of Medicine, Jinan University, 510632, Guangzhou, Guangdong, China
| | - Yin Luo
- Department of Pharmacology, Emory University School of Medicine and Winship Cancer Institute of Emory University, 1510 Clifton Rd. NE, Atlanta, GA, 30322, USA
| | - Kurt Warncke
- Department of Physics, Emory University, 400 Dowman Drive, Atlanta, GA, 30322, USA
| | - Youwei Sun
- Departments of Radiation Oncology, Emory University School of Medicine and Winship Cancer Institute of Emory University, 1365C Clifton Road NE, Atlanta, GA, 30322, USA
| | - David S Yu
- Departments of Radiation Oncology, Emory University School of Medicine and Winship Cancer Institute of Emory University, 1365C Clifton Road NE, Atlanta, GA, 30322, USA
| | - Haian Fu
- Department of Pharmacology, Emory University School of Medicine and Winship Cancer Institute of Emory University, 1510 Clifton Rd. NE, Atlanta, GA, 30322, USA
| | - Madhusmita Behera
- Department of Hematology and Medical Oncology, Emory University School of Medicine and Winship Cancer Institute of Emory University, 1365C Clifton Road NE, Atlanta, GA, 30322, USA
| | - Suresh S Ramalingam
- Department of Hematology and Medical Oncology, Emory University School of Medicine and Winship Cancer Institute of Emory University, 1365C Clifton Road NE, Atlanta, GA, 30322, USA
| | - Paul W Doetsch
- Laboratory of Genome Integrity and Structural Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, 27709, USA
| | - Duc M Duong
- Department of Biochemistry, Emory University School of Medicine, 1510 Clifton Rd. NE, Atlanta, GA, 30322, USA
| | - Michael Lammers
- Institute of Biochemistry, Synthetic and Structural Biochemistry, University of Greifswald, Felix-Hausdorff-Str. 4, Greifswald, 17487, Germany
| | - Walter J Curran
- Departments of Radiation Oncology, Emory University School of Medicine and Winship Cancer Institute of Emory University, 1365C Clifton Road NE, Atlanta, GA, 30322, USA
| | - Xingming Deng
- Departments of Radiation Oncology, Emory University School of Medicine and Winship Cancer Institute of Emory University, 1365C Clifton Road NE, Atlanta, GA, 30322, USA.
| |
Collapse
|
16
|
Park PSH. Rhodopsin Oligomerization and Aggregation. J Membr Biol 2019; 252:413-423. [PMID: 31286171 DOI: 10.1007/s00232-019-00078-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 06/25/2019] [Indexed: 12/18/2022]
Abstract
Rhodopsin is the light receptor in photoreceptor cells of the retina and a prototypical G protein-coupled receptor. Two types of quaternary structures can be adopted by rhodopsin. If rhodopsin folds and attains a proper tertiary structure, it can then form oligomers and nanodomains within the photoreceptor cell membrane. In contrast, if rhodopsin misfolds, it cannot progress through the biosynthetic pathway and instead will form aggregates that can cause retinal degenerative disease. In this review, emerging views are highlighted on the supramolecular organization of rhodopsin within the membrane of photoreceptor cells and the aggregation of rhodopsin that can lead to retinal degeneration.
Collapse
Affiliation(s)
- Paul S-H Park
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH, 44106, USA.
| |
Collapse
|
17
|
Li Z, Chen G, Chen L, Zhang Y, Dai Z. Solution Properties of Alkyl β‐D‐Maltosides. J SURFACTANTS DETERG 2019. [DOI: 10.1002/jsde.12281] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Zhencao Li
- College of Chemistry, Key Laboratory of Environmentally Friendly Chemistry and Application of Ministry of EducationXiangtan University Xiangtan, 411105 Hunan People's Republic of China Republic of China
| | - Guoyong Chen
- College of Chemistry, Key Laboratory of Environmentally Friendly Chemistry and Application of Ministry of EducationXiangtan University Xiangtan, 411105 Hunan People's Republic of China Republic of China
| | - Langqiu Chen
- College of Chemistry, Key Laboratory of Environmentally Friendly Chemistry and Application of Ministry of EducationXiangtan University Xiangtan, 411105 Hunan People's Republic of China Republic of China
| | - Yanhua Zhang
- College of Chemistry, Key Laboratory of Environmentally Friendly Chemistry and Application of Ministry of EducationXiangtan University Xiangtan, 411105 Hunan People's Republic of China Republic of China
| | - Zhiyong Dai
- Ausnutria Dairy (China) Co. Ltd. Changsha, 410005 Hunan People's Republic of China
| |
Collapse
|
18
|
Ortega JT, Parmar T, Jastrzebska B. Flavonoids enhance rod opsin stability, folding, and self-association by directly binding to ligand-free opsin and modulating its conformation. J Biol Chem 2019; 294:8101-8122. [PMID: 30944172 DOI: 10.1074/jbc.ra119.007808] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 03/27/2019] [Indexed: 12/29/2022] Open
Abstract
Rhodopsin (Rho) is a visual G protein-coupled receptor expressed in the rod photoreceptors of the eye, where it mediates transmission of a light signal into a cell and converts this signal into a nerve impulse. More than 100 mutations in Rho are linked to various ocular impairments, including retinitis pigmentosa (RP). Accordingly, much effort has been directed toward developing ligands that target Rho and improve its folding and stability. Natural compounds may provide another viable approach to such drug discovery efforts. The dietary polyphenol compounds, ubiquitously present in fruits and vegetables, have beneficial effects in several eye diseases. However, the underlying mechanism of their activity is not fully understood. In this study, we used a combination of computational methods, biochemical and biophysical approaches, including bioluminescence resonance energy transfer, and mammalian cell expression systems to clarify the effects of four common bioactive flavonoids (quercetin, myricetin, and their mono-glycosylated forms quercetin-3-rhamnoside and myricetrin) on rod opsin stability, function, and membrane organization. We observed that by directly interacting with ligand-free opsin, flavonoids modulate its conformation, thereby causing faster entry of the retinal chromophore into its binding pocket. Moreover, flavonoids significantly increased opsin stability, most likely by introducing structural rigidity and promoting receptor self-association within the biological membranes. Of note, the binding of flavonoids to an RP-linked P23H opsin variant partially restored its normal cellular trafficking. Together, our results suggest that flavonoids could be utilized as lead compounds in the development of effective nonretinoid therapeutics for managing RP-related retinopathies.
Collapse
Affiliation(s)
- Joseph T Ortega
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106
| | - Tanu Parmar
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106
| | - Beata Jastrzebska
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106.
| |
Collapse
|
19
|
Disruption of Rhodopsin Dimerization in Mouse Rod Photoreceptors by Synthetic Peptides Targeting Dimer Interface. Methods Mol Biol 2019; 1753:115-128. [PMID: 29564785 DOI: 10.1007/978-1-4939-7720-8_8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
Abstract
Synthetic peptides derived from transmembrane segments of G protein-coupled receptors (GPCR) are used to disrupt GPCR dimer interface. This peptide competition technique is an effective approach to map the dimer interface of GPCR and its functional significance. Here we present a technique to deliver synthetic transmembrane peptides to living mouse rod photoreceptors to disrupt rhodopsin (a prototypical member of Class A GPCRs) dimer formation in the endoplasmic reticulum (ER). We have shown that rhodopsin helix H1- or H8-peptide caused mislocalization of rhodopsin to the perinuclear endoplasmic reticulum (ER).
Collapse
|
20
|
Perera SMDC, Chawla U, Shrestha UR, Bhowmik D, Struts AV, Qian S, Chu XQ, Brown MF. Small-Angle Neutron Scattering Reveals Energy Landscape for Rhodopsin Photoactivation. J Phys Chem Lett 2018; 9:7064-7071. [PMID: 30489081 DOI: 10.1021/acs.jpclett.8b03048] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Knowledge of the activation principles for G-protein-coupled receptors (GPCRs) is critical to development of new pharmaceuticals. Rhodopsin is the archetype for the largest GPCR family, yet the changes in protein dynamics that trigger signaling are not fully understood. Here we show that rhodopsin can be investigated by small-angle neutron scattering (SANS) in fully protiated detergent micelles under contrast matching to resolve light-induced changes in the protein structure. In SANS studies of membrane proteins, the zwitterionic detergent [(cholamidopropyl)dimethylammonio]-propanesulfonate (CHAPS) is advantageous because of the low contrast difference between the hydrophobic core and hydrophilic head groups as compared with alkyl glycoside detergents. Combining SANS results with quasielastic neutron scattering reveals how changes in volumetric protein shape are coupled (slaved) to the aqueous solvent. Upon light exposure, rhodopsin is swollen by the penetration of water into the protein core, allowing interactions with effector proteins in the visual signaling mechanism.
Collapse
Affiliation(s)
- Suchithranga M D C Perera
- Department of Chemistry and Biochemistry , University of Arizona , Tucson , Arizona 85721 , United States
| | - Udeep Chawla
- Department of Chemistry and Biochemistry , University of Arizona , Tucson , Arizona 85721 , United States
| | - Utsab R Shrestha
- Department of Physics and Astronomy , Wayne State University , Detroit , Michigan 48201 , United States
| | - Debsindhu Bhowmik
- Department of Physics and Astronomy , Wayne State University , Detroit , Michigan 48201 , United States
| | - Andrey V Struts
- Department of Chemistry and Biochemistry , University of Arizona , Tucson , Arizona 85721 , United States
- Laboratory of Biomolecular NMR , St. Petersburg State University , St. Petersburg 199034 , Russia
| | - Shuo Qian
- Neutron Scattering Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Xiang-Qiang Chu
- Graduate School of China Academy of Engineering Physics , Beijing 100193 , China
| | - Michael F Brown
- Department of Chemistry and Biochemistry , University of Arizona , Tucson , Arizona 85721 , United States
- Department of Physics , University of Arizona , Tucson , Arizona 85721 , United States
| |
Collapse
|
21
|
Mallory DP, Gutierrez E, Pinkevitch M, Klinginsmith C, Comar WD, Roushar FJ, Schlebach JP, Smith AW, Jastrzebska B. The Retinitis Pigmentosa-Linked Mutations in Transmembrane Helix 5 of Rhodopsin Disrupt Cellular Trafficking Regardless of Oligomerization State. Biochemistry 2018; 57:5188-5201. [PMID: 30085663 DOI: 10.1021/acs.biochem.8b00403] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
G protein-coupled receptors can exist as dimers and higher-order oligomers in biological membranes. The specific oligomeric assembly of these receptors is believed to play a major role in their function, and the disruption of native oligomers has been implicated in specific human pathologies. Computational predictions and biochemical analyses suggest that two molecules of rhodopsin (Rho) associate through the interactions involving its fifth transmembrane helix (TM5). Interestingly, there are several pathogenic loss-of-function mutations within TM5 that face the lipid bilayer in a manner that could potentially influence the dimerization of Rho. Though several of these mutations are known to induce misfolding, the pathogenic defects associated with V209M and F220C Rho remain unclear. In this work, we utilized a variety of biochemical and biophysical approaches to elucidate the effects of these mutations on the dimerization, folding, trafficking, and function of Rho in relation to other pathogenic TM5 variants. Chemical cross-linking, bioluminescence energy transfer, and pulsed-interleaved excitation fluorescence cross-correlation spectroscopy experiments revealed that each of these mutants exhibits a wild type-like propensity to self-associate within the plasma membrane. However, V209M and F220C each exhibit subtle defects in cellular trafficking. Together, our results suggest that the RP pathology associated with the expression of the V209M and F220C mutants could arise from defects in folding and cellular trafficking rather than the disruption of dimerization, as has been previously proposed.
Collapse
Affiliation(s)
- D Paul Mallory
- Department of Chemistry , University of Akron , 190 Buchtel Common , Akron , Ohio 44325 , United States
| | - Elizabeth Gutierrez
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine , Case Western Reserve University , 10900 Euclid Avenue , Cleveland , Ohio 44106 , United States
| | - Margaret Pinkevitch
- Department of Chemistry , University of Akron , 190 Buchtel Common , Akron , Ohio 44325 , United States
| | - Christie Klinginsmith
- Department of Chemistry , University of Akron , 190 Buchtel Common , Akron , Ohio 44325 , United States
| | - William D Comar
- Department of Chemistry , University of Akron , 190 Buchtel Common , Akron , Ohio 44325 , United States
| | - Francis J Roushar
- Department of Chemistry , Indiana University , 800 East Kirkwood Avenue , Bloomington , Indiana 47405-7102 , United States
| | - Jonathan P Schlebach
- Department of Chemistry , Indiana University , 800 East Kirkwood Avenue , Bloomington , Indiana 47405-7102 , United States
| | - Adam W Smith
- Department of Chemistry , University of Akron , 190 Buchtel Common , Akron , Ohio 44325 , United States
| | - Beata Jastrzebska
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine , Case Western Reserve University , 10900 Euclid Avenue , Cleveland , Ohio 44106 , United States
| |
Collapse
|
22
|
Gurevich VV, Gurevich EV. GPCRs and Signal Transducers: Interaction Stoichiometry. Trends Pharmacol Sci 2018; 39:672-684. [PMID: 29739625 DOI: 10.1016/j.tips.2018.04.002] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 04/11/2018] [Accepted: 04/13/2018] [Indexed: 12/12/2022]
Abstract
Until the late 1990s, class A G protein-coupled receptors (GPCRs) were believed to function as monomers. Indirect evidence that they might internalize or even signal as dimers has emerged, along with proof that class C GPCRs are obligatory dimers. Crystal structures of GPCRs and their much larger binding partners were consistent with the idea that two receptors might engage a single G protein, GRK, or arrestin. However, recent biophysical, biochemical, and structural evidence invariably suggests that a single GPCR binds G proteins, GRKs, and arrestins. Here we review existing evidence of the stoichiometry of GPCR interactions with signal transducers and discuss potential biological roles of class A GPCR oligomers, including proposed homo- and heterodimers.
Collapse
Affiliation(s)
- Vsevolod V Gurevich
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA.
| | - Eugenia V Gurevich
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
| |
Collapse
|
23
|
Dimer Interface of the Human Serotonin Transporter and Effect of the Membrane Composition. Sci Rep 2018; 8:5080. [PMID: 29572541 PMCID: PMC5865177 DOI: 10.1038/s41598-018-22912-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 03/02/2018] [Indexed: 12/11/2022] Open
Abstract
The oligomeric state of membrane proteins has recently emerged in many cases as having an effect on their function. However, the intrinsic dynamics of their spatial organization in cells and model systems makes it challenging to characterize. Here we use molecular dynamics (MD) simulations at multiple resolutions to determine the dimer conformation of the human serotonin transporter (hSERT). From self-assembly simulations we predict dimer candidates and subsequently quantify their relative strength. We use umbrella sampling (US) replica exchange MD simulations for which we present extensive analysis of their efficiency and improved sampling compared to regular US MD simulations. The data shows that the most stable hSERT dimer interface is symmetrical and involves transmembrane helix 12 (TM12), similar to the crystal structure of the bacterial homologue LeuT, but with a slightly different orientation. We also describe the supramolecular organization of hSERT from a 250 μs self-assembly simulation. Finally, the effects of the presence of phosphatidylinositol bisphosphate or cholesterol in the membrane model has been quantified for the TM12-TM12 predicted interface. Collectively, the presented data bring new insight to the area of protein and lipid interplay in biological membranes.
Collapse
|
24
|
Wang L, Yuan Y, Chen X, Chen J, Guo Y, Li M, Li C, Pu X. Probing the cooperative mechanism of the μ–δ opioid receptor heterodimer by multiscale simulation. Phys Chem Chem Phys 2018; 20:29969-29982. [DOI: 10.1039/c8cp06652c] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The activation-cooperativity of the μ–δ opioid receptor heterodimer was probed by multiscale simulation coupled with a protein structure network.
Collapse
Affiliation(s)
- Longrong Wang
- Faculty of Chemistry
- Sichuan University
- Chengdu
- People's Republic of China
| | - Yuan Yuan
- College of Management
- Southwest University for Nationalities
- Chengdu 610041
- P. R. China
| | - Xin Chen
- Faculty of Chemistry
- Sichuan University
- Chengdu
- People's Republic of China
| | - Jiangfan Chen
- Faculty of Chemistry
- Sichuan University
- Chengdu
- People's Republic of China
| | - Yanzhi Guo
- Faculty of Chemistry
- Sichuan University
- Chengdu
- People's Republic of China
| | - Menglong Li
- Faculty of Chemistry
- Sichuan University
- Chengdu
- People's Republic of China
| | - Chuan Li
- College of Computer Science
- Sichuan University
- Chengdu
- P. R. China
| | - Xuemei Pu
- Faculty of Chemistry
- Sichuan University
- Chengdu
- People's Republic of China
| |
Collapse
|
25
|
Recent advances in biophysical studies of rhodopsins - Oligomerization, folding, and structure. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017; 1865:1512-1521. [PMID: 28844743 DOI: 10.1016/j.bbapap.2017.08.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2017] [Revised: 08/06/2017] [Accepted: 08/11/2017] [Indexed: 12/19/2022]
Abstract
Retinal-binding proteins, mainly known as rhodopsins, function as photosensors and ion transporters in a wide range of organisms. From halobacterial light-driven proton pump, bacteriorhodopsin, to bovine photoreceptor, visual rhodopsin, they have served as prototypical α-helical membrane proteins in a large number of biophysical studies and aided in the development of many cutting-edge techniques of structural biology and biospectroscopy. In the last decade, microbial and animal rhodopsin families have expanded significantly, bringing into play a number of new interesting structures and functions. In this review, we will discuss recent advances in biophysical approaches to retinal-binding proteins, primarily microbial rhodopsins, including those in optical spectroscopy, X-ray crystallography, nuclear magnetic resonance, and electron paramagnetic resonance, as applied to such fundamental biological aspects as protein oligomerization, folding, and structure.
Collapse
|
26
|
Charoensapyanan R, Takahashi Y, Murakami S, Ito K, Rudeekulthamrong P, Kaulpiboon J. Synthesis, structural characterization, and biological properties of pentyl- and isopentyl-α-D-glucosides. APPL BIOCHEM MICRO+ 2017. [DOI: 10.1134/s0003683817040020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
27
|
Photocyclic behavior of rhodopsin induced by an atypical isomerization mechanism. Proc Natl Acad Sci U S A 2017; 114:E2608-E2615. [PMID: 28289214 DOI: 10.1073/pnas.1617446114] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Vertebrate rhodopsin (Rh) contains 11-cis-retinal as a chromophore to convert light energy into visual signals. On absorption of light, 11-cis-retinal is isomerized to all-trans-retinal, constituting a one-way reaction that activates transducin (Gt) followed by chromophore release. Here we report that bovine Rh, regenerated instead with a six-carbon-ring retinal chromophore featuring a C11=C12 double bond locked in its cis conformation (Rh6mr), employs an atypical isomerization mechanism by converting 11-cis to an 11,13-dicis configuration for prolonged Gt activation. Time-dependent UV-vis spectroscopy, HPLC, and molecular mechanics analyses revealed an atypical thermal reisomerization of the 11,13-dicis to the 11-cis configuration on a slow timescale, which enables Rh6mr to function in a photocyclic manner similar to that of microbial Rhs. With this photocyclic behavior, Rh6mr repeatedly recruits and activates Gt in response to light stimuli, making it an excellent candidate for optogenetic tools based on retinal analog-bound vertebrate Rhs. Overall, these comprehensive structure-function studies unveil a unique photocyclic mechanism of Rh activation by an 11-cis-to-11,13-dicis isomerization.
Collapse
|
28
|
Quistgaard EM, Martinez Molledo M, Löw C. Structure determination of a major facilitator peptide transporter: Inward facing PepTSt from Streptococcus thermophilus crystallized in space group P3121. PLoS One 2017; 12:e0173126. [PMID: 28264013 PMCID: PMC5338821 DOI: 10.1371/journal.pone.0173126] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 02/15/2017] [Indexed: 12/03/2022] Open
Abstract
Major facilitator superfamily (MFS) peptide transporters (typically referred to as PepT, POT or PTR transporters) mediate the uptake of di- and tripeptides, and so play an important dietary role in many organisms. In recent years, a better understanding of the molecular basis for this process has emerged, which is in large part due to a steep increase in structural information. Yet, the conformational transitions underlying the transport mechanism are still not fully understood, and additional data is therefore needed. Here we report in detail the detergent screening, crystallization, experimental MIRAS phasing, and refinement of the peptide transporter PepTSt from Streptococcus thermophilus. The space group is P3121, and the protein is crystallized in a monomeric inward facing form. The binding site is likely to be somewhat occluded, as the lobe encompassing transmembrane helices 10 and 11 is markedly bent towards the central pore of the protein, but the extent of this potential occlusion could not be determined due to disorder at the apex of the lobe. Based on structural comparisons with the seven previously determined P212121 and C2221 structures of inward facing PepTSt, the structural flexibility as well as the conformational changes mediating transition between the inward open and inward facing occluded states are discussed. In conclusion, this report improves our understanding of the structure and conformational cycle of PepTSt, and can furthermore serve as a case study, which may aid in supporting future structure determinations of additional MFS transporters or other integral membrane proteins.
Collapse
Affiliation(s)
- Esben M. Quistgaard
- Centre for Structural Systems Biology (CSSB), DESY and European Molecular Biology Laboratory Hamburg, Hamburg, Germany
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Maria Martinez Molledo
- Centre for Structural Systems Biology (CSSB), DESY and European Molecular Biology Laboratory Hamburg, Hamburg, Germany
| | - Christian Löw
- Centre for Structural Systems Biology (CSSB), DESY and European Molecular Biology Laboratory Hamburg, Hamburg, Germany
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
- * E-mail:
| |
Collapse
|
29
|
Ji B, Liu H, Zhang R, Jiang Y, Wang C, Li S, Chen J, Bai B. Novel signaling of dynorphin at κ-opioid receptor/bradykinin B2 receptor heterodimers. Cell Signal 2017; 31:66-78. [PMID: 28069442 DOI: 10.1016/j.cellsig.2017.01.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 12/19/2016] [Accepted: 01/04/2017] [Indexed: 01/06/2023]
Abstract
The κ-opioid receptor (KOR) and bradykinin B2 receptor (B2R) are involved in a variety of important physiological processes and share many similar characteristics in terms of their distribution and functions in the nervous system. We first demonstrated the endogenous expression of KOR and B2R in human SH-SY5Y cells and their co-localization on the membrane of human embryonic kidney 293 (HEK293) cells. Bioluminescence and fluorescence resonance energy transfer and the proximity ligation assay were exploited to demonstrate the formation of functional KOR and B2R heteromers in transfected cells. KOR/B2R heteromers triggered dynorphin A (1-13)-induced Gαs/protein kinase A signaling pathway activity, including upregulation of intracellular cAMP levels and cAMP-response element luciferase reporter activity, resulting in increased cAMP-response element-binding protein (CREB) phosphorylation, which could be dampened by the protein kinase A (PKA) inhibitor H89. This indicated that the co-existence of KOR and B2R is critical for CREB phosphorylation. In addition, dynorphin A (1-13) induced a significantly higher rate of proliferation in HEK293-KOR/B2R and human SH-SY5Y cells than in the control group. These results indicate that KOR can form a heterodimer with B2R and this leads to increased protein kinase A activity by the CREB signaling pathway, leading to a significant increase in cell proliferation. The nature of this signaling pathway has significant implications for the role of dynorphin in the regulation of neuroprotective effects.
Collapse
Affiliation(s)
- Bingyuan Ji
- School of Life Science, Shandong Agricultural University, Taian 271018, PR China; Neurobiology Institute, Jining Medical University, Jining 272067, PR China
| | - Haiqing Liu
- Department of Physiology, Taishan Medical College, Taian 271000, PR China
| | - Rumin Zhang
- Neurobiology Institute, Jining Medical University, Jining 272067, PR China
| | - Yunlu Jiang
- Neurobiology Institute, Jining Medical University, Jining 272067, PR China
| | - Chunmei Wang
- Neurobiology Institute, Jining Medical University, Jining 272067, PR China
| | - Sheng Li
- Neurobiology Institute, Jining Medical University, Jining 272067, PR China
| | - Jing Chen
- Neurobiology Institute, Jining Medical University, Jining 272067, PR China; Division of Translational and Systems Medicine, Warwick Medical School, University of Warwick, Coventry, UK.
| | - Bo Bai
- Neurobiology Institute, Jining Medical University, Jining 272067, PR China.
| |
Collapse
|
30
|
Capra V, Mauri M, Guzzi F, Busnelli M, Accomazzo MR, Gaussem P, Nisar SP, Mundell SJ, Parenti M, Rovati GE. Impaired thromboxane receptor dimerization reduces signaling efficiency: A potential mechanism for reduced platelet function in vivo. Biochem Pharmacol 2016; 124:43-56. [PMID: 27845050 DOI: 10.1016/j.bcp.2016.11.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 11/10/2016] [Indexed: 12/16/2022]
Abstract
Thromboxane A2 is a potent mediator of inflammation and platelet aggregation exerting its effects through the activation of a G protein-coupled receptor (GPCR), termed TP. Although the existence of dimers/oligomers in Class A GPCRs is widely accepted, their functional significance still remains controversial. Recently, we have shown that TPα and TPβ homo-/hetero-dimers interact through an interface of residues in transmembrane domain 1 (TM1) whose disruption impairs dimer formation. Here, biochemical and pharmacological characterization of this dimer deficient mutant (DDM) in living cells indicates a significant impairment in its response to agonists. Interestingly, two single loss-of-function TPα variants, namely W29C and N42S recently identified in two heterozygous patients affected by bleeding disorders, match some of the residues mutated in our DDM. These two naturally occurring variants display a reduced potency to TP agonists and are characterized by impaired dimer formation in transfected HEK-293T cells. These findings provide proofs that lack of homo-dimer formation is a crucial process for reduced TPα function in vivo, and might represent one molecular mechanism through which platelet TPα receptor dysfunction affects the patient(s) carrying these mutations.
Collapse
Key Words
- (Z)-7-[(1R,2R,3R,4S)-3-[[2-(phenylcarbamoyl)hydrazinyl]methyl]-7-oxabicyclo[2.2.1]heptan-2-yl]hept-5-enoic acid
- (Z)-7-[(1S,2S,3R,4R)-3-[(E,3S)-3-hydroxyoct-1-enyl]-5-oxabicyclo[2.2.1]heptan-2-yl]hept-5-enoic acid
- (Z)-7-[(1S,2S,3S,4R)-3-[(E,3R)-3-hydroxy-4-(4-iodophenoxy)but-1-enyl]-7-oxabicyclo[2.2.1]heptan-2-yl]hept-5-enoic acid
- (Z)-7-[(1S,3R,4R,5S)-3-[(E,3R)-3-hydroxyoct-1-enyl]-6,6-dimethyl-4-bicyclo[3.1.1]heptanyl]hept-5-enoic acid
- 3-[(3R)-3-[(4-fluorophenyl)sulfonylamino]-1,2,3,4-tetrahydrocarbazol-9-yl]propanoic acid
- Eicosanoids
- G protein coupled receptors
- I-BOP (PubChem CID: 51015454)
- Pinane Thromboxane A2 (PTA2) (PubChem CID: 25834471)
- Platelets
- Ramatroban (PubChem CID: 123879)
- Receptor dimer
- SQ29,548 (PubChem CID: 6437074)
- Signal transduction
- Thromboxane A(2)
- U46619 (PubChem CID: 5311493)
Collapse
Affiliation(s)
- Valérie Capra
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milano, Italy; Department of Health Science, University of Milan, Milano, Italy.
| | - Mario Mauri
- Department of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy.
| | - Francesca Guzzi
- Department of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy.
| | - Marta Busnelli
- CNR, Institute of Neuroscience, University of Milan, Milan, Italy; Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy.
| | - Maria Rosa Accomazzo
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milano, Italy.
| | - Pascale Gaussem
- Inserm UMR-S1140, Faculte' de Pharmacie, Université Paris Descartes, Sorbonne Paris Cité, Paris and AP-HP, Hopital Européen Georges Pompidou, Service d'Hématologie Biologique, Paris, France.
| | - Shaista P Nisar
- School of Physiology and Pharmacology, University of Bristol, Bristol BS8 1TD, UK.
| | - Stuart J Mundell
- School of Physiology and Pharmacology, University of Bristol, Bristol BS8 1TD, UK.
| | - Marco Parenti
- Department of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy.
| | - G Enrico Rovati
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milano, Italy.
| |
Collapse
|
31
|
|
32
|
|
33
|
Jastrzebska B, Chen Y, Orban T, Jin H, Hofmann L, Palczewski K. Disruption of Rhodopsin Dimerization with Synthetic Peptides Targeting an Interaction Interface. J Biol Chem 2015; 290:25728-44. [PMID: 26330551 DOI: 10.1074/jbc.m115.662684] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Indexed: 11/06/2022] Open
Abstract
Although homo- and heterodimerizations of G protein-coupled receptors (GPCRs) are well documented, GPCR monomers are able to assemble in different ways, thus causing variations in the interactive interface between receptor monomers among different GPCRs. Moreover, the functional consequences of this phenomenon, which remain to be clarified, could be specific for different GPCRs. Synthetic peptides derived from transmembrane (TM) domains can interact with a full-length GPCR, blocking dimer formation and affecting its function. Here we used peptides corresponding to TM helices of bovine rhodopsin (Rho) to investigate the Rho dimer interface and functional consequences of its disruption. Incubation of Rho with TM1, TM2, TM4, and TM5 peptides in rod outer segment (ROS) membranes shifted the resulting detergent-solubilized protein migration through a gel filtration column toward smaller molecular masses with a reduced propensity for dimer formation in a cross-linking reaction. Binding of these TM peptides to Rho was characterized by both mass spectrometry and a label-free assay from which dissociation constants were calculated. A BRET (bioluminescence resonance energy transfer) assay revealed that the physical interaction between Rho molecules expressed in membranes of living cells was blocked by the same four TM peptides identified in our in vitro experiments. Although disruption of the Rho dimer/oligomer had no effect on the rates of G protein activation, binding of Gt to the activated receptor stabilized the dimer. However, TM peptide-induced disruption of dimer/oligomer decreased receptor stability, suggesting that Rho supramolecular organization could be essential for ROS stabilization and receptor trafficking.
Collapse
Affiliation(s)
- Beata Jastrzebska
- From the Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4965
| | - Yuanyuan Chen
- From the Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4965
| | - Tivadar Orban
- From the Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4965
| | - Hui Jin
- From the Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4965
| | - Lukas Hofmann
- From the Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4965
| | - Krzysztof Palczewski
- From the Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4965
| |
Collapse
|
34
|
Gunkel M, Schöneberg J, Alkhaldi W, Irsen S, Noé F, Kaupp UB, Al-Amoudi A. Higher-order architecture of rhodopsin in intact photoreceptors and its implication for phototransduction kinetics. Structure 2015; 23:628-38. [PMID: 25728926 DOI: 10.1016/j.str.2015.01.015] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Revised: 01/16/2015] [Accepted: 01/22/2015] [Indexed: 12/23/2022]
Abstract
The visual pigment rhodopsin belongs to the family of G protein-coupled receptors that can form higher oligomers. It is controversial whether rhodopsin forms oligomers and whether oligomers are functionally relevant. Here, we study rhodopsin organization in cryosections of dark-adapted mouse rod photoreceptors by cryoelectron tomography. We identify four hierarchical levels of organization. Rhodopsin forms dimers; at least ten dimers form a row. Rows form pairs (tracks) that are aligned parallel to the disk incisures. Particle-based simulation shows that the combination of tracks with fast precomplex formation, i.e. rapid association and dissociation between inactive rhodopsin and the G protein transducin, leads to kinetic trapping: rhodopsin first activates transducin from its own track, whereas recruitment of transducin from other tracks proceeds more slowly. The trap mechanism could produce uniform single-photon responses independent of rhodopsin lifetime. In general, tracks might provide a platform that coordinates the spatiotemporal interaction of signaling molecules.
Collapse
Affiliation(s)
- Monika Gunkel
- Department of Molecular Sensory Systems, Center of Advanced European Studies and Research (caesar), Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Johannes Schöneberg
- Computational Molecular Biology Group, Freie Universität Berlin, Arnimallee 6, 14195 Berlin, Germany
| | - Weaam Alkhaldi
- German Center of Neurodegenerative Diseases, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Stephan Irsen
- Department of Molecular Sensory Systems, Center of Advanced European Studies and Research (caesar), Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Frank Noé
- Computational Molecular Biology Group, Freie Universität Berlin, Arnimallee 6, 14195 Berlin, Germany
| | - U Benjamin Kaupp
- Department of Molecular Sensory Systems, Center of Advanced European Studies and Research (caesar), Ludwig-Erhard-Allee 2, 53175 Bonn, Germany.
| | - Ashraf Al-Amoudi
- German Center of Neurodegenerative Diseases, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany.
| |
Collapse
|
35
|
Palczewski K. Chemistry and biology of the initial steps in vision: the Friedenwald lecture. Invest Ophthalmol Vis Sci 2014; 55:6651-72. [PMID: 25338686 DOI: 10.1167/iovs.14-15502] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Visual transduction is the process in the eye whereby absorption of light in the retina is translated into electrical signals that ultimately reach the brain. The first challenge presented by visual transduction is to understand its molecular basis. We know that maintenance of vision is a continuous process requiring the activation and subsequent restoration of a vitamin A-derived chromophore through a series of chemical reactions catalyzed by enzymes in the retina and retinal pigment epithelium (RPE). Diverse biochemical approaches that identified key proteins and reactions were essential to achieve a mechanistic understanding of these visual processes. The three-dimensional arrangements of these enzymes' polypeptide chains provide invaluable insights into their mechanisms of action. A wealth of information has already been obtained by solving high-resolution crystal structures of both rhodopsin and the retinoid isomerase from pigment RPE (RPE65). Rhodopsin, which is activated by photoisomerization of its 11-cis-retinylidene chromophore, is a prototypical member of a large family of membrane-bound proteins called G protein-coupled receptors (GPCRs). RPE65 is a retinoid isomerase critical for regeneration of the chromophore. Electron microscopy (EM) and atomic force microscopy have provided insights into how certain proteins are assembled to form much larger structures such as rod photoreceptor cell outer segment membranes. A second challenge of visual transduction is to use this knowledge to devise therapeutic approaches that can prevent or reverse conditions leading to blindness. Imaging modalities like optical coherence tomography (OCT) and scanning laser ophthalmoscopy (SLO) applied to appropriate animal models as well as human retinal imaging have been employed to characterize blinding diseases, monitor their progression, and evaluate the success of therapeutic agents. Lately two-photon (2-PO) imaging, together with biochemical assays, are revealing functional aspects of vision at a new molecular level. These multidisciplinary approaches combined with suitable animal models and inbred mutant species can be especially helpful in translating provocative cell and tissue culture findings into therapeutic options for further development in animals and eventually in humans. A host of different approaches and techniques is required for substantial progress in understanding fundamental properties of the visual system.
Collapse
Affiliation(s)
- Krzysztof Palczewski
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States
| |
Collapse
|
36
|
Armando S, Quoyer J, Lukashova V, Maiga A, Percherancier Y, Heveker N, Pin JP, Prézeau L, Bouvier M. The chemokine CXC4 and CC2 receptors form homo- and heterooligomers that can engage their signaling G-protein effectors and βarrestin. FASEB J 2014; 28:4509-23. [PMID: 25053617 DOI: 10.1096/fj.13-242446] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
G-protein-coupled receptors have been shown to assemble at least as dimers early in the biosynthetic path, but some evidence suggests that they can also form larger oligomeric complexes. Using the human chemokine receptors CXCR4 and CCR2 as models, we directly probed the existence of higher order homo- and heterooligomers in human embryonic kidney cells. Combining bimolecular fluorescence and luminescence complementation (BiFC, BiLC) with bioluminescence resonance energy transfer (BRET) assays, we show that CXCR4 and CCR2 can assemble as homo- and heterooligomers, forming at least tetramers. Selective activation of CCR2 with the human monocyte chemotactic protein 1 (MCP-1) resulted in trans-conformational rearrangement of the CXCR4 dimer with an EC50 of 19.9 nM, compatible with a CCR2 action. Moreover, MCP-1 promoted the engagement of Gαi1, Gα13, Gαz, and βarrestin2 to the heterooligomer, resulting in calcium signaling that was synergistically potentiated on coactivation of CCR2 and CXCR4, demonstrating that complexes larger than dimers reach the cell surface as functional units. A mutation of CXCR4 (N119K), which prevents Gi activation, also affects the CCR2-promoted engagement of Gαi1 and βarrestin2 by the heterooligomer, supporting the occurrence of transprotomer regulation. Together, the results demonstrate that homo- and heteromultimeric CXCR4 and CCR2 can form functional signaling complexes that have unique properties.
Collapse
Affiliation(s)
- Sylvain Armando
- Department of Biochemistry, Institute for Research in Immunology and Cancer, and Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche (UMR) 5203, Institut National de la Santé et de la Recherche Médicale (INSERM) U661, University of Montpellier 1 and 2, Montpellier, France
| | - Julie Quoyer
- Department of Biochemistry, Institute for Research in Immunology and Cancer, and
| | - Viktorya Lukashova
- Department of Biochemistry, Institute for Research in Immunology and Cancer, and
| | - Arhamatoulaye Maiga
- Department of Biochemistry, Institute for Research in Immunology and Cancer, and
| | - Yann Percherancier
- Department of Biochemistry, Institute for Research in Immunology and Cancer, and
| | - Nikolaus Heveker
- Department of Biochemistry, Research Centre/Hôpital Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada; and
| | - Jean-Philippe Pin
- Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche (UMR) 5203, Institut National de la Santé et de la Recherche Médicale (INSERM) U661, University of Montpellier 1 and 2, Montpellier, France
| | - Laurent Prézeau
- Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche (UMR) 5203, Institut National de la Santé et de la Recherche Médicale (INSERM) U661, University of Montpellier 1 and 2, Montpellier, France
| | - Michel Bouvier
- Department of Biochemistry, Institute for Research in Immunology and Cancer, and
| |
Collapse
|
37
|
Dimers of G-protein coupled receptors as versatile storage and response units. Int J Mol Sci 2014; 15:4856-77. [PMID: 24651459 PMCID: PMC3975428 DOI: 10.3390/ijms15034856] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 02/28/2014] [Accepted: 03/04/2014] [Indexed: 11/17/2022] Open
Abstract
The status and use of transmembrane, extracellular and intracellular domains in oligomerization of heptahelical G-protein coupled receptors (GPCRs) are reviewed and for transmembrane assemblies also supplemented by new experimental evidence. The transmembrane-linked GPCR oligomers typically have as the minimal unit an asymmetric ~180 kDa pentamer consisting of receptor homodimer or heterodimer and a G-protein αβγ subunit heterotrimer. With neuropeptide Y (NPY) receptors, this assembly is converted to ~90 kDa receptor monomer-Gα complex by receptor and Gα agonists, and dimers/heteropentamers are depleted by neutralization of Gαi subunits by pertussis toxin. Employing gradient centrifugation, quantification and other characterization of GPCR dimers at the level of physically isolated and identified heteropentamers is feasible with labeled agonists that do not dissociate upon solubilization. This is demonstrated with three neuropeptide Y (NPY) receptors and could apply to many receptors that use large peptidic agonists.
Collapse
|
38
|
Schott RK, Refvik SP, Hauser FE, López-Fernández H, Chang BSW. Divergent positive selection in rhodopsin from lake and riverine cichlid fishes. Mol Biol Evol 2014; 31:1149-65. [PMID: 24509690 DOI: 10.1093/molbev/msu064] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Studies of cichlid evolution have highlighted the importance of visual pigment genes in the spectacular radiation of the African rift lake cichlids. Recent work, however, has also provided strong evidence for adaptive diversification of riverine cichlids in the Neotropics, which inhabit environments of markedly different spectral properties from the African rift lakes. These ecological and/or biogeographic differences may have imposed divergent selective pressures on the evolution of the cichlid visual system. To test these hypotheses, we investigated the molecular evolution of the dim-light visual pigment, rhodopsin. We sequenced rhodopsin from Neotropical and African riverine cichlids and combined these data with published sequences from African cichlids. We found significant evidence for positive selection using random sites codon models in all cichlid groups, with the highest levels in African lake cichlids. Tests using branch-site and clade models that partitioned the data along ecological (lake, river) and/or biogeographic (African, Neotropical) boundaries found significant evidence of divergent selective pressures among cichlid groups. However, statistical comparisons among these models suggest that ecological, rather than biogeographic, factors may be responsible for divergent selective pressures that have shaped the evolution of the visual system in cichlids. We found that branch-site models did not perform as well as clade models for our data set, in which there was evidence for positive selection in the background. One of our most intriguing results is that the amino acid sites found to be under positive selection in Neotropical and African lake cichlids were largely nonoverlapping, despite falling into the same three functional categories: spectral tuning, retinal uptake/release, and rhodopsin dimerization. Taken together, these results would imply divergent selection across cichlid clades, but targeting similar functions. This study highlights the importance of molecular investigations of ecologically important groups and the flexibility of clade models in explicitly testing ecological hypotheses.
Collapse
Affiliation(s)
- Ryan K Schott
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
| | | | | | | | | |
Collapse
|
39
|
Roche D, Gil D, Giraldo J. Mathematical modeling of G protein-coupled receptor function: what can we learn from empirical and mechanistic models? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 796:159-81. [PMID: 24158805 DOI: 10.1007/978-94-007-7423-0_8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Empirical and mechanistic models differ in their approaches to the analysis of pharmacological effect. Whereas the parameters of the former are not physical constants those of the latter embody the nature, often complex, of biology. Empirical models are exclusively used for curve fitting, merely to characterize the shape of the E/[A] curves. Mechanistic models, on the contrary, enable the examination of mechanistic hypotheses by parameter simulation. Regretfully, the many parameters that mechanistic models may include can represent a great difficulty for curve fitting, representing, thus, a challenge for computational method development. In the present study some empirical and mechanistic models are shown and the connections, which may appear in a number of cases between them, are analyzed from the curves they yield. It may be concluded that systematic and careful curve shape analysis can be extremely useful for the understanding of receptor function, ligand classification and drug discovery, thus providing a common language for the communication between pharmacologists and medicinal chemists.
Collapse
Affiliation(s)
- David Roche
- Laboratory of Systems Pharmacology and Bioinformatics, Institut de Neurociències and Unitat de Bioestadística, Universitat Autònoma de Barcelona, 08193, Bellaterra, Spain
| | | | | |
Collapse
|
40
|
Cardoso MVC, Sabadini E. Before and beyond the micellization of n-alkyl glycosides. A water-1H NMR relaxation study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:15778-15786. [PMID: 24308316 DOI: 10.1021/la403526w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The interactions between the headgroups of n-alkyl glycoside (AG) and water molecules were studied by nuclear magnetic transverse relaxation times (T2) of the water protons before and beyond the micellization. Despite the low concentration of the surfactants (mM), their micellization induce strong effect on the T2 values of bulk water when the AG molecules self-aggregate into micelles. This is associated with the decreasing of the fraction of OH headgroups of AG to exchange protons with water molecules due to the OH headgroups intermolecular interactions of AG at the micelle surface. These findings support the computational results described in the literature, which indicate that the water hydrogen bonding to OH headgroups is perturbed at AG micelle surfaces.
Collapse
Affiliation(s)
- Marcus V C Cardoso
- Department of Physical Chemistry, Institute of Chemistry, University of Campinas - UNICAMP . P.O. Box 6154, 13084-862, Campinas, SP, Brazil
| | | |
Collapse
|
41
|
Jastrzebska B. GPCR: G protein complexes--the fundamental signaling assembly. Amino Acids 2013; 45:1303-14. [PMID: 24052187 DOI: 10.1007/s00726-013-1593-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 09/10/2013] [Indexed: 12/15/2022]
Abstract
G protein coupled receptors (GPCR) constitute the largest group of cell surface receptors that transmit various signals across biological membranes through the binding and activation of heterotrimeric G proteins, which amplify the signal and activate downstream effectors leading to the biological responses. Thus, the first critical step in this signaling cascade is the interaction between receptor and its cognate G protein. Understanding this critical event at the molecular level is of high importance because abnormal function of GPCRs is associated with many diseases. Thus, these receptors are targets for drug development.
Collapse
Affiliation(s)
- Beata Jastrzebska
- Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH, 44106-4965, USA,
| |
Collapse
|
42
|
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.
Collapse
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.
| |
Collapse
|
43
|
Cascella M, Bärfuss S, Stocker A. Cis-retinoids and the chemistry of vision. Arch Biochem Biophys 2013; 539:187-95. [PMID: 23791723 DOI: 10.1016/j.abb.2013.06.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 06/04/2013] [Accepted: 06/10/2013] [Indexed: 11/17/2022]
Abstract
We discuss here principal biochemical transformations of retinoid molecules in the visual cycle. We focus our analysis on the accumulating evidence of alternate pathways and functional redundancies in the cycle. The efficiency of the visual cycle depends, on one hand, on fast regeneration of the photo-bleached chromophores. On the other hand, it is crucial that the cyclic process should be highly selective to avoid accumulation of byproducts. The state-of-the-art knowledge indicates that single enzymatically active components of the cycle are not strictly selective and may require chaperones to enhance their rates. It appears that protein-protein interactions significantly improve the biological stability of the visual cycle. In particular, synthesis of thermodynamically less stable 11-cis-retinoid conformers is favored by physical interactions of the isomerases present in the retina with cellular retinaldehyde binding protein.
Collapse
Affiliation(s)
- Michele Cascella
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland.
| | | | | |
Collapse
|
44
|
Palczewski K, Orban T. From atomic structures to neuronal functions of g protein-coupled receptors. Annu Rev Neurosci 2013; 36:139-64. [PMID: 23682660 DOI: 10.1146/annurev-neuro-062012-170313] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
G protein-coupled receptors (GPCRs) are essential mediators of signal transduction, neurotransmission, ion channel regulation, and other cellular events. GPCRs are activated by diverse stimuli, including light, enzymatic processing of their N-termini, and binding of proteins, peptides, or small molecules such as neurotransmitters. GPCR dysfunction caused by receptor mutations and environmental challenges contributes to many neurological diseases. Moreover, modern genetic technology has helped identify a rich array of mono- and multigenic defects in humans and animal models that connect such receptor dysfunction with disease affecting neuronal function. The visual system is especially suited to investigate GPCR structure and function because advanced imaging techniques permit structural studies of photoreceptor neurons at both macro and molecular levels that, together with biochemical and physiological assessment in animal models, provide a more complete understanding of GPCR signaling.
Collapse
Affiliation(s)
- Krzysztof Palczewski
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4965, USA.
| | | |
Collapse
|
45
|
Jastrzebska B, Ringler P, Palczewski K, Engel A. The rhodopsin-transducin complex houses two distinct rhodopsin molecules. J Struct Biol 2013; 182:164-72. [PMID: 23458690 DOI: 10.1016/j.jsb.2013.02.014] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2012] [Revised: 02/02/2013] [Accepted: 02/19/2013] [Indexed: 10/27/2022]
Abstract
Upon illumination the visual receptor rhodopsin (Rho) transitions to the activated form Rho(∗), which binds the heterotrimeric G protein, transducin (Gt) causing GDP to GTP exchange and Gt dissociation. Using succinylated concanavalin A (sConA) as a probe, we visualized native Rho dimers solubilized in 1mM n-dodecyl-β-d-maltoside (DDM) and Rho monomers in 5mM DDM. By nucleotide depletion and affinity chromatography together with crosslinking and size exclusion chromatography, we trapped and purified nucleotide-free Rho(∗)·Gt and sConA-Rho(∗)·Gt complexes kept in solution by either DDM or lauryl-maltose-neopentyl-glycol (LMNG). The 3 D envelope calculated from projections of negatively stained Rho(∗)·Gt-LMNG complexes accommodated two Rho molecules, one Gt heterotrimer and a detergent belt. Visualization of triple sConA-Rho(∗)·Gt complexes unequivocally demonstrated a pentameric assembly of the Rho(∗)·Gt complex in which the photoactivated Rho(∗) dimer serves as a platform for binding the Gt heterotrimer. Importantly, individual monomers of the Rho(∗) dimer in the heteropentameric complex exhibited different capabilities for regeneration with either 11-cis or 9-cis-retinal.
Collapse
Affiliation(s)
- Beata Jastrzebska
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106-4965, USA.
| | | | | | | |
Collapse
|
46
|
Latek D, Modzelewska A, Trzaskowski B, Palczewski K, Filipek S. G protein-coupled receptors--recent advances. Acta Biochim Pol 2012; 59:515-529. [PMID: 23251911 PMCID: PMC4322417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 12/05/2012] [Accepted: 12/10/2012] [Indexed: 06/01/2023]
Abstract
The years 2000 and 2007 witnessed milestones in current understanding of G protein-coupled receptor (GPCR) structural biology. In 2000 the first GPCR, bovine rhodopsin, was crystallized and the structure was solved, while in 2007 the structure of β(2)-adrenergic receptor, the first GPCR with diffusible ligands, was determined owing to advances in microcrystallization and an insertion of the fast-folding lysozyme into the receptor. In parallel with those crystallographic studies, the biological and biochemical characterization of GPCRs has advanced considerably because those receptors are molecular targets for many of currently used drugs. Therefore, the mechanisms of activation and signal transduction to the cell interior deduced from known GPCRs structures are of the highest importance for drug discovery. These proteins are the most diversified membrane receptors encoded by hundreds of genes in our genome. They participate in processes responsible for vision, smell, taste and neuronal transmission in response to photons or binding of ions, hormones, peptides, chemokines and other factors. Although the GPCRs share a common seven-transmembrane α-helical bundle structure their binding sites can accommodate thousands of different ligands. The ligands, including agonists, antagonists or inverse agonists change the structure of the receptor. With bound agonists they can form a complex with a suitable G protein, be phosphorylated by kinases or bind arrestin. The discovered signaling cascades invoked by arrestin independently of G proteins makes the GPCR activating scheme more complex such that a ligand acting as an antagonist for G protein signaling can also act as an agonist in arrestin-dependent signaling. Additionally, the existence of multiple ligand-dependent partial activation states as well as dimerization of GPCRs result in a 'microprocessor-like' action of these receptors rather than an 'on-off' switch as was commonly believed only a decade ago.
Collapse
Affiliation(s)
- Dorota Latek
- Biomodeling Laboratory, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Anna Modzelewska
- Biomodeling Laboratory, Faculty of Chemistry, University of Warsaw, Warsaw, Poland
| | - Bartosz Trzaskowski
- Biomodeling Laboratory, Faculty of Chemistry, University of Warsaw, Warsaw, Poland
| | - Krzysztof Palczewski
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio USA
| | - Sławomir Filipek
- Biomodeling Laboratory, Faculty of Chemistry, University of Warsaw, Warsaw, Poland
| |
Collapse
|
47
|
Structural insights on the plant salt-overly-sensitive 1 (SOS1) Na(+)/H(+) antiporter. J Mol Biol 2012; 424:283-94. [PMID: 23022605 DOI: 10.1016/j.jmb.2012.09.015] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Revised: 09/07/2012] [Accepted: 09/17/2012] [Indexed: 11/20/2022]
Abstract
The Arabidopsisthaliana Na(+)/H(+) antiporter salt-overly-sensitive 1 (SOS1) is essential to maintain low intracellular levels of toxic Na(+) under salt stress. Available data show that the plant SOS2 protein kinase and its interacting activator, the SOS3 calcium-binding protein, function together in decoding calcium signals elicited by salt stress and regulating the phosphorylation state and the activity of SOS1. Molecular genetic studies have shown that the activation implies a domain reorganization of the antiporter cytosolic moiety, indicating that there is a clear relationship between function and molecular structure of the antiporter. To provide information on this issue, we have carried out in vivo and in vitro studies on the oligomerization state of SOS1. In addition, we have performed electron microscopy and single-particle reconstruction of negatively stained full-length and active SOS1. Our studies show that the protein is a homodimer that contains a membrane domain similar to that found in other antiporters of the family and an elongated, large, and structured cytosolic domain. Both the transmembrane (TM) and cytosolic moieties contribute to the dimerization of the antiporter. The close contacts between the TM and the cytosolic domains provide a link between regulation and transport activity of the antiporter.
Collapse
|
48
|
Conformational dynamics of activation for the pentameric complex of dimeric G protein-coupled receptor and heterotrimeric G protein. Structure 2012; 20:826-40. [PMID: 22579250 DOI: 10.1016/j.str.2012.03.017] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2012] [Revised: 03/05/2012] [Accepted: 03/05/2012] [Indexed: 01/08/2023]
Abstract
Photoactivation of rhodopsin (Rho), a G protein-coupled receptor, causes conformational changes that provide a specific binding site for the rod G protein, G(t). In this work we employed structural mass spectrometry techniques to elucidate the structural changes accompanying transition of ground state Rho to photoactivated Rho (Rho(∗)) and in the pentameric complex between dimeric Rho(∗) and heterotrimeric G(t). Observed differences in hydroxyl radical labeling and deuterium uptake between Rho(∗) and the (Rho(∗))(2)-G(t) complex suggest that photoactivation causes structural relaxation of Rho following its initial tightening upon G(t) coupling. In contrast, nucleotide-free G(t) in the complex is significantly more accessible to deuterium uptake allowing it to accept GTP and mediating complex dissociation. Thus, we provide direct evidence that in the critical step of signal amplification, Rho(∗) and G(t) exhibit dissimilar conformational changes when they are coupled in the (Rho(∗))(2)-G(t) complex.
Collapse
|
49
|
Cangiano L, Asteriti S, Cervetto L, Gargini C. The photovoltage of rods and cones in the dark-adapted mouse retina. J Physiol 2012; 590:3841-55. [PMID: 22641773 DOI: 10.1113/jphysiol.2011.226878] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Research on photoreceptors has led to important insights into how light signals are detected and processed in the outer retina. Most information about photoreceptor function, however, comes from lower vertebrates. The large majority of mammalian studies are based on suction pipette recordings of outer segment currents, a technique that doesn't allow examination of phenomena occurring downstream of phototransduction. Only a small number of whole-cell recordings have been made, mainly in the macaque. Due to the growing importance of the mouse in vision research, we have optimized a retinal slice preparation that allows the reliable collection of perforated-patch recordings from light responding rods and cones. Unexpectedly, the frequency of cone recordings was much higher than their numeric proportion of ∼3%. This allowed us to obtain direct functional evidence suggestive of rod–cone coupling in the mouse. Moreover, rods had considerably larger single photon responses than previously published for mammals (3.44 mV, SD 1.37, n = 19 at 24°C; 2.46 mV, SD 1.08, n = 10 at 36°C), and a relatively high signal/noise ratio (6.4, SD 1.8 at 24°C; 6.8, SD 2.8 at 36°C). Both findings imply a more favourable transmission at the rod–rod bipolar cell synapse. Accordingly, relatively few photoisomerizations were sufficient to elicit a half-maximal response (6.7, SD 2.7, n = 5 at 24°C; 10.6, SD 1.7, n = 3 at 36°C), leading to a narrow linear response range. Our study demonstrates new features of mammalian photoreceptors and opens the way for further investigations into photoreceptor function using retinas from mutant mouse models.
Collapse
Affiliation(s)
- Lorenzo Cangiano
- Department of Physiological Sciences, University of Pisa, Via San Zeno 31, I-56123 Pisa, Italy.
| | | | | | | |
Collapse
|
50
|
Cordomí A, Perez JJ. Structural Rearrangements of Rhodopsin Subunits in a Dimer Complex: a Molecular Dynamics Simulation Study. J Biomol Struct Dyn 2012; 27:127-47. [DOI: 10.1080/07391102.2009.10507303] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Arnau Cordomí
- a Dept d'Enginyeria Química , Technical University of Catalonia (UPC), ETS d'Enginyeria Industrial , Av. Diagonal 647, 08028 , Barcelona , Spain
| | - Juan J. Perez
- a Dept d'Enginyeria Química , Technical University of Catalonia (UPC), ETS d'Enginyeria Industrial , Av. Diagonal 647, 08028 , Barcelona , Spain
| |
Collapse
|