1
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Yee C, Görtemaker K, Wellpott R, Koch KW. Kinetics of cone specific G-protein signaling in avian photoreceptor cells. Front Mol Neurosci 2023; 16:1107025. [PMID: 36733826 PMCID: PMC9887155 DOI: 10.3389/fnmol.2023.1107025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 01/03/2023] [Indexed: 01/19/2023] Open
Abstract
Cone photoreceptor cells of night-migratory songbirds seem to process the primary steps of two different senses, vision and magnetoreception. The molecular basis of phototransduction is a prototypical G protein-coupled receptor pathway starting with the photoexcitation of rhodopsin or cone opsin thereby activating a heterotrimeric G protein named transducin. This interaction is well understood in vertebrate rod cells, but parameter describing protein-protein interactions of cone specific proteins are rare and not available for migratory birds. European robin is a model organism for studying the orientation of birds in the earth magnetic field. Recent findings showed a link between the putative magnetoreceptor cryptochrome 4a and the cone specific G-protein of European robin. In the present work, we investigated the interaction of European robin cone specific G protein and cytoplasmic regions of long wavelength opsin. We identified the second loop in opsin connecting transmembrane regions three and four as a critical binding interface. Surface plasmon resonance studies using a synthetic peptide representing the second cytoplasmic loop and purified G protein α-subunit showed a high affinity interaction with a K D value of 21 nM. Truncation of the G protein α-subunit at the C-terminus by six amino acids slightly decreased the affinity. Our results suggest that binding of the G protein to cryptochrome can compete with the interaction of G protein and non-photoexcited long wavelength opsin. Thus, the parallel presence of two different sensory pathways in bird cone photoreceptors is reasonable under dark-adapted conditions or during illumination with short wavelengths.
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Affiliation(s)
- Chad Yee
- Division of Biochemistry, Department of Neuroscience, University of Oldenburg, Oldenburg, Germany
| | - Katharina Görtemaker
- Division of Biochemistry, Department of Neuroscience, University of Oldenburg, Oldenburg, Germany
| | - Rieke Wellpott
- Division of Biochemistry, Department of Neuroscience, University of Oldenburg, Oldenburg, Germany
| | - Karl-Wilhelm Koch
- Division of Biochemistry, Department of Neuroscience, University of Oldenburg, Oldenburg, Germany,Research Center Neurosensory Sciences, University of Oldenburg, Oldenburg, Germany,*Correspondence: Karl-Wilhelm Koch, ✉
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2
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Direct Interaction of Avian Cryptochrome 4 with a Cone Specific G-Protein. Cells 2022; 11:cells11132043. [PMID: 35805127 PMCID: PMC9265643 DOI: 10.3390/cells11132043] [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] [Received: 05/31/2022] [Revised: 06/23/2022] [Accepted: 06/24/2022] [Indexed: 02/04/2023] Open
Abstract
Background: Night-migratory birds sense the Earth’s magnetic field by an unknown molecular mechanism. Theoretical and experimental evidence support the hypothesis that the light-induced formation of a radical-pair in European robin cryptochrome 4a (ErCry4a) is the primary signaling step in the retina of the bird. In the present work, we investigated a possible route of cryptochrome signaling involving the α-subunit of the cone-secific heterotrimeric G protein from European robin. Methods: Protein–protein interaction studies include surface plasmon resonance, pulldown affinity binding and Förster resonance energy transfer. Results: Surface plasmon resonance studies showed direct interaction, revealing high to moderate affinity for binding of non-myristoylated and myristoylated G protein to ErCry4a, respectively. Pulldown affinity experiments confirmed this complex formation in solution. We validated these in vitro data by monitoring the interaction between ErCry4a and G protein in a transiently transfected neuroretinal cell line using Förster resonance energy transfer. Conclusions: Our results suggest that ErCry4a and the G protein also interact in living cells and might constitute the first biochemical signaling step in radical-pair-based magnetoreception.
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3
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Jain S, Sekhar A. Elucidating the mechanisms underlying protein conformational switching using NMR spectroscopy. JOURNAL OF MAGNETIC RESONANCE OPEN 2022; 10-11:100034. [PMID: 35586549 PMCID: PMC7612731 DOI: 10.1016/j.jmro.2022.100034] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
How proteins switch between various ligand-free and ligand-bound structures has been a key biophysical question ever since the postulation of the Monod-Wyman-Changeux and Koshland-Nemethy-Filmer models over six decades ago. The ability of NMR spectroscopy to provide structural and kinetic information on biomolecular conformational exchange places it in a unique position as an analytical tool to interrogate the mechanisms of biological processes such as protein folding and biomolecular complex formation. In addition, recent methodological developments in the areas of saturation transfer and relaxation dispersion have expanded the scope of NMR for probing the mechanics of transitions in systems where one or more states constituting the exchange process are sparsely populated and 'invisible' in NMR spectra. In this review, we highlight some of the strategies available from NMR spectroscopy for examining the nature of multi-site conformational exchange, using five case studies that have employed NMR, either in isolation, or in conjunction with other biophysical tools.
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4
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Abbas S, Koch KW. Label-free Quantification of Direct Protein-protein Interactions with Backscattering Interferometry. Bio Protoc 2021; 11:e4256. [PMID: 35087916 DOI: 10.21769/bioprotoc.4256] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 10/04/2021] [Accepted: 10/07/2021] [Indexed: 12/25/2022] Open
Abstract
The functional performance of a cell depends on how macromolecules, in particular proteins, come together in a precise orientation, how they assemble into protein complexes and interact with each other. In order to study protein-protein interactions at a molecular level, a variety of methods to investigate these binding processes yield affinity constants and/or the identification of binding regions. There are several well-established biophysical techniques for biomolecular interaction studies, such as fluorescence spectroscopy and surface plasmon resonance. Although these techniques have been proven to be efficient, they either need labeling or immobilization of one interaction partner. Backscattering interferometry (BSI) is a label-free detection method, which allows label- and immobilization-free interaction analysis under physiologically relevant conditions with high sensitivity and in small volumes. We used BSI to measure the interaction of the neuronal calcium sensor recoverin with its target G protein-coupled receptor kinase 1 (GRK1) as a model system. Increasing concentrations of purified recoverin were mixed with a specific concentration of a GRK1 fusion protein. In this protocol, we provide a full description of the instrumental setup, data acquisition, and evaluation. Equilibrium dissociation constants of recoverin-GRK1 interaction determined by the BSI instrumental setup are in full agreement with affinity constants obtained by different methods as described in the literature.
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Affiliation(s)
- Seher Abbas
- Department of Neuroscience, University of Oldenburg, Oldenburg D-26129, Germany
| | - Karl-Wilhelm Koch
- Department of Neuroscience, University of Oldenburg, Oldenburg D-26129, Germany
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5
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Marino V, Riva M, Zamboni D, Koch KW, Dell'Orco D. Bringing the Ca 2+ sensitivity of myristoylated recoverin into the physiological range. Open Biol 2021; 11:200346. [PMID: 33401992 PMCID: PMC7881174 DOI: 10.1098/rsob.200346] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The prototypical Ca2+-sensor protein recoverin (Rec) is thought to regulate the activity of rhodopsin kinase (GRK1) in photoreceptors by switching from a relaxed (R) disc membrane-bound conformation in the dark to a more compact, cytosol-diffusing tense (T) conformation upon cell illumination. However, the apparent affinity for Ca2+ of its physiologically relevant form (myristoylated recoverin) is almost two orders of magnitude too low to support this mechanism in vivo. In this work, we compared the individual and synergistic roles of the myristic moiety, the GRK1 target and the disc membrane in modulating the calcium sensitivity of Rec. We show that the sole presence of the target or the disc membrane alone are not sufficient to achieve a physiological response to changes in intracellular [Ca2+]. Instead, the simultaneous presence of GRK1 and membrane allows the T to R transition to occur in a physiological range of [Ca2+] with high cooperativity via a conformational selection mechanism that drives the structural transitions of Rec in the presence of multiple ligands. Our conclusions may apply to other sensory transduction systems involving protein complexes and biological membranes.
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Affiliation(s)
- Valerio Marino
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, 37134 Verona, Italy
| | - Matteo Riva
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, 37134 Verona, Italy.,Department of Neuroscience, Division of Biochemistry, University of Oldenburg, 26111 Oldenburg, Germany
| | - Davide Zamboni
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, 37134 Verona, Italy.,Department of Neuroscience, Division of Biochemistry, University of Oldenburg, 26111 Oldenburg, Germany
| | - Karl-Wilhelm Koch
- Department of Neuroscience, Division of Biochemistry, University of Oldenburg, 26111 Oldenburg, Germany
| | - Daniele Dell'Orco
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, 37134 Verona, Italy
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6
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Ahrens N, Elbers D, Greb H, Janssen-Bienhold U, Koch KW. Interaction of G protein-coupled receptor kinases and recoverin isoforms is determined by localization in zebrafish photoreceptors. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1868:118946. [PMID: 33385424 DOI: 10.1016/j.bbamcr.2020.118946] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 12/22/2020] [Accepted: 12/23/2020] [Indexed: 12/14/2022]
Abstract
The zebrafish retina expresses four recoverin genes (rcv1a, rcv1b, rcv2a and rcv2b) and four opsin kinase genes (grk1a, grk1b, grk7a and grk7b) coding for recoverin and G protein-coupled receptor kinase (opsin kinase) paralogs, respectively. Both protein groups are suggested to form regulatory complexes in rod and cone outer segments, but at present, we lack information about co-localization of recoverin and opsin kinases in zebrafish retinae and which protein-protein interacting pairs form. We analyzed the distribution and co-localization of recoverin and opsin kinase expression in the zebrafish retina. For this purpose, we used custom-tailored monospecific antibodies revealing that the amount of recoverin paralogs in a zebrafish retina can differ by more than one order of magnitude with the highest amount for recoverin 1a and 2b. Further, immunohistochemical labelling showed presence of recoverin 1a in all rod cell compartments, but it only co-localized with opsin kinase 1a in rod outer segments. In contrast, recoverin 2b was only detected in double cones and co-localized with opsin kinases 1b, 7a and 7b. Further, we investigated the interaction between recoverin and opsin kinase variants by surface plasmon resonance spectroscopy indicating interaction of recoverin 1a and recoverin 2b with all opsin kinases. However, binding kinetics for recoverin 1a differed from those observed with recoverin 2b that showed slower association and dissociation processes. Our results indicate diverse recoverin and opsin kinase properties due to differential expression and interaction profiles.
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Affiliation(s)
- Nicole Ahrens
- Department of Neuroscience, Division of Biochemistry, University of Oldenburg, 26111 Oldenburg, Germany
| | - Dana Elbers
- Department of Neuroscience, Division of Biochemistry, University of Oldenburg, 26111 Oldenburg, Germany
| | - Helena Greb
- Department of Neuroscience, Division of Biochemistry, University of Oldenburg, 26111 Oldenburg, Germany
| | - Ulrike Janssen-Bienhold
- Department of Neuroscience, Division of Neurobiology, University of Oldenburg, 26111 Oldenburg, Germany
| | - Karl-Wilhelm Koch
- Department of Neuroscience, Division of Biochemistry, University of Oldenburg, 26111 Oldenburg, Germany.
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7
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Komolov KE, Sulon SM, Bhardwaj A, van Keulen SC, Duc NM, Laurinavichyute DK, Lou HJ, Turk BE, Chung KY, Dror RO, Benovic JL. Structure of a GRK5-Calmodulin Complex Reveals Molecular Mechanism of GRK Activation and Substrate Targeting. Mol Cell 2020; 81:323-339.e11. [PMID: 33321095 DOI: 10.1016/j.molcel.2020.11.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 09/15/2020] [Accepted: 11/12/2020] [Indexed: 10/22/2022]
Abstract
The phosphorylation of G protein-coupled receptors (GPCRs) by GPCR kinases (GRKs) facilitates arrestin binding and receptor desensitization. Although this process can be regulated by Ca2+-binding proteins such as calmodulin (CaM) and recoverin, the molecular mechanisms are poorly understood. Here, we report structural, computational, and biochemical analysis of a CaM complex with GRK5, revealing how CaM shapes GRK5 response to calcium. The CaM N and C domains bind independently to two helical regions at the GRK5 N and C termini to inhibit GPCR phosphorylation, though only the C domain interaction disrupts GRK5 membrane association, thereby facilitating cytoplasmic translocation. The CaM N domain strongly activates GRK5 via ordering of the amphipathic αN-helix of GRK5 and allosteric disruption of kinase-RH domain interaction for phosphorylation of cytoplasmic GRK5 substrates. These results provide a framework for understanding how two functional effects, GRK5 activation and localization, can cooperate under control of CaM for selective substrate targeting by GRK5.
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Affiliation(s)
- Konstantin E Komolov
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Sarah M Sulon
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Anshul Bhardwaj
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Siri C van Keulen
- Department of Computer Science, Department of Molecular and Cellular Physiology, Department of Structural Biology, and Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Nguyen Minh Duc
- School of Pharmacy, Sungkyunkwan University, Suwon 16419, South Korea; Division of Precision Medicine, Research Institute, National Cancer Center, Goyang, South Korea
| | - Daniela K Laurinavichyute
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Hua Jane Lou
- Department of Pharmacology, Yale School of Medicine, New Haven, CT 06520, USA
| | - Benjamin E Turk
- Department of Pharmacology, Yale School of Medicine, New Haven, CT 06520, USA
| | - Ka Young Chung
- School of Pharmacy, Sungkyunkwan University, Suwon 16419, South Korea
| | - Ron O Dror
- Department of Computer Science, Department of Molecular and Cellular Physiology, Department of Structural Biology, and Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA 94305, USA; Biophysics Program, Stanford University, Stanford, CA 94305, USA
| | - Jeffrey L Benovic
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA.
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8
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Lankford CK, Laird JG, Inamdar SM, Baker SA. A Comparison of the Primary Sensory Neurons Used in Olfaction and Vision. Front Cell Neurosci 2020; 14:595523. [PMID: 33250719 PMCID: PMC7676898 DOI: 10.3389/fncel.2020.595523] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Accepted: 10/06/2020] [Indexed: 12/18/2022] Open
Abstract
Vision, hearing, smell, taste, and touch are the tools used to perceive and navigate the world. They enable us to obtain essential resources such as food and highly desired resources such as mates. Thanks to the investments in biomedical research the molecular unpinning’s of human sensation are rivaled only by our knowledge of sensation in the laboratory mouse. Humans rely heavily on vision whereas mice use smell as their dominant sense. Both modalities have many features in common, starting with signal detection by highly specialized primary sensory neurons—rod and cone photoreceptors (PR) for vision, and olfactory sensory neurons (OSN) for the smell. In this chapter, we provide an overview of how these two types of primary sensory neurons operate while highlighting the similarities and distinctions.
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Affiliation(s)
- Colten K Lankford
- Department of Biochemistry, University of Iowa, Iowa City, IA, United States
| | - Joseph G Laird
- Department of Biochemistry, University of Iowa, Iowa City, IA, United States
| | - Shivangi M Inamdar
- Department of Biochemistry, University of Iowa, Iowa City, IA, United States
| | - Sheila A Baker
- Department of Biochemistry, University of Iowa, Iowa City, IA, United States.,Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, IA, United States
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9
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Borsatto A, Marino V, Abrusci G, Lattanzi G, Dell'Orco D. Effects of Membrane and Biological Target on the Structural and Allosteric Properties of Recoverin: A Computational Approach. Int J Mol Sci 2019; 20:ijms20205009. [PMID: 31658639 PMCID: PMC6829511 DOI: 10.3390/ijms20205009] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 10/01/2019] [Accepted: 10/08/2019] [Indexed: 12/12/2022] Open
Abstract
Recoverin (Rec) is a prototypical calcium sensor protein primarily expressed in the vertebrate retina. The binding of two Ca2+ ions to the functional EF-hand motifs induces the extrusion of a myristoyl group that increases the affinity of Rec for the membrane and leads to the formation of a complex with rhodopsin kinase (GRK1). Here, unbiased all-atom molecular dynamics simulations were performed to monitor the spontaneous insertion of the myristoyl group into a model multicomponent biological membrane for both isolated Rec and for its complex with a peptide from the GRK1 target. It was found that the functional membrane anchoring of the myristoyl group is triggered by persistent electrostatic protein-membrane interactions. In particular, salt bridges between Arg43, Arg46 and polar heads of phosphatidylserine lipids are necessary to enhance the myristoyl hydrophobic packing in the Rec-GRK1 assembly. The long-distance communication between Ca2+-binding EF-hands and residues at the interface with GRK1 is significantly influenced by the presence of the membrane, which leads to dramatic changes in the connectivity of amino acids mediating the highest number of persistent interactions (hubs). In conclusion, specific membrane composition and allosteric interactions are both necessary for the correct assembly and dynamics of functional Rec-GRK1 complex.
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Affiliation(s)
- Alberto Borsatto
- Department of Neuroscience, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, 37134 Verona, Italy.
- Department of Physics, University of Trento, 38123 Trento, Italy.
| | - Valerio Marino
- Department of Neuroscience, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, 37134 Verona, Italy.
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56026 Pisa, Italy.
| | - Gianfranco Abrusci
- Department of Physics, University of Trento, 38123 Trento, Italy.
- Trento Institute for Fundamental Physics and Applications (INFN-TIFPA), Via Sommarive 14, Povo, 38123 Trento, Italy.
| | - Gianluca Lattanzi
- Department of Physics, University of Trento, 38123 Trento, Italy.
- Trento Institute for Fundamental Physics and Applications (INFN-TIFPA), Via Sommarive 14, Povo, 38123 Trento, Italy.
| | - Daniele Dell'Orco
- Department of Neuroscience, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, 37134 Verona, Italy.
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10
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Tsvetkov PO, Roman AY, Baksheeva VE, Nazipova AA, Shevelyova MP, Vladimirov VI, Buyanova MF, Zinchenko DV, Zamyatnin AA, Devred F, Golovin AV, Permyakov SE, Zernii EY. Functional Status of Neuronal Calcium Sensor-1 Is Modulated by Zinc Binding. Front Mol Neurosci 2018; 11:459. [PMID: 30618610 PMCID: PMC6302015 DOI: 10.3389/fnmol.2018.00459] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2018] [Accepted: 11/28/2018] [Indexed: 11/29/2022] Open
Abstract
Neuronal calcium sensor-1 (NCS-1) protein is abundantly expressed in the central nervous system and retinal neurons, where it regulates many vital processes such as synaptic transmission. It coordinates three calcium ions by EF-hands 2-4, thereby transducing Ca2+ signals to a wide range of protein targets, including G protein-coupled receptors and their kinases. Here, we demonstrate that NCS-1 also has Zn2+-binding sites, which affect its structural and functional properties upon filling. Fluorescence and circular dichroism experiments reveal the impact of Zn2+ binding on NCS-1 secondary and tertiary structure. According to atomic absorption spectroscopy and isothermal titration calorimetry studies, apo-NCS-1 has two high-affinity (4 × 106 M-1) and one low-affinity (2 × 105 M-1) Zn2+-binding sites, whereas Mg2+-loaded and Ca2+-loaded forms (which dominate under physiological conditions) bind two zinc ions with submicromolar affinity. Metal competition analysis and circular dichroism studies suggest that Zn2+-binding sites of apo- and Mg2+-loaded NCS-1 overlap with functional EF-hands of the protein. Consistently, high Zn2+ concentrations displace Mg2+ from the EF-hands and decrease the stoichiometry of Ca2+ binding. Meanwhile, one of the EF-hands of Zn2+-saturated NCS-1 exhibits a 14-fold higher calcium affinity, which increases the overall calcium sensitivity of the protein. Based on QM/MM molecular dynamics simulations, Zn2+ binding to Ca2+-loaded NCS-1 could occur at EF-hands 2 and 4. The high-affinity zinc binding increases the thermal stability of Ca2+-free NCS-1 and favours the interaction of its Ca2+-loaded form with target proteins, such as dopamine receptor D2R and GRK1. In contrast, low-affinity zinc binding promotes NCS-1 aggregation accompanied by the formation of twisted rope-like structures. Altogether, our findings suggest a complex interplay between magnesium, calcium and zinc binding to NCS-1, leading to the appearance of multiple conformations of the protein, in turn modulating its functional status.
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Affiliation(s)
- Philipp O Tsvetkov
- Aix-Marseille University, CNRS, INP, Institute of Neurophysiopathology, Faculty of Pharmacy, Marseille, France
| | - Andrei Yu Roman
- Institute of Physiologically Active Compounds (RAS), Chernogolovka, Russia
| | - Viktoriia E Baksheeva
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Aliya A Nazipova
- Institute for Biological Instrumentation of the Russian Academy of Sciences, Pushchino, Russia
| | - Marina P Shevelyova
- Institute for Biological Instrumentation of the Russian Academy of Sciences, Pushchino, Russia
| | - Vasiliy I Vladimirov
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Pushchino, Russia
| | - Michelle F Buyanova
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russia
| | - Dmitry V Zinchenko
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Pushchino, Russia
| | - Andrey A Zamyatnin
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
- Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Moscow, Russia
| | - François Devred
- Aix-Marseille University, CNRS, INP, Institute of Neurophysiopathology, Faculty of Pharmacy, Marseille, France
| | - Andrey V Golovin
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russia
- Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Moscow, Russia
- Faculty of Computer Science, Higher School of Economics, Moscow, Russia
| | - Sergei E Permyakov
- Institute for Biological Instrumentation of the Russian Academy of Sciences, Pushchino, Russia
| | - Evgeni Yu Zernii
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
- Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Moscow, Russia
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11
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Ames JB. Dimerization of Neuronal Calcium Sensor Proteins. Front Mol Neurosci 2018; 11:397. [PMID: 30450035 PMCID: PMC6224351 DOI: 10.3389/fnmol.2018.00397] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 10/11/2018] [Indexed: 12/27/2022] Open
Abstract
Neuronal calcium sensor (NCS) proteins are EF-hand containing Ca2+ binding proteins that regulate sensory signal transduction. Many NCS proteins (recoverin, GCAPs, neurocalcin and visinin-like protein 1 (VILIP1)) form functional dimers under physiological conditions. The dimeric NCS proteins have similar amino acid sequences (50% homology) but each bind to and regulate very different physiological targets. Retinal recoverin binds to rhodopsin kinase and promotes Ca2+-dependent desensitization of light-excited rhodopsin during visual phototransduction. The guanylyl cyclase activating proteins (GCAP1–5) each bind and activate retinal guanylyl cyclases (RetGCs) in light-adapted photoreceptors. VILIP1 binds to membrane targets that modulate neuronal secretion. Here, I review atomic-level structures of dimeric forms of recoverin, GCAPs and VILIP1. The distinct dimeric structures in each case suggest that NCS dimerization may play a role in modulating specific target recognition. The dimerization of recoverin and VILIP1 is Ca2+-dependent and enhances their membrane-targeting Ca2+-myristoyl switch function. The dimerization of GCAP1 and GCAP2 facilitate their binding to dimeric RetGCs and may allosterically control the Ca2+-dependent activation of RetGCs.
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Affiliation(s)
- James B Ames
- Department of Chemistry, University of California, Davis, Davis, CA, United States
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12
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Lundy SK, Nikoopour E, Karoukis AJ, Ohara R, Othman MI, Tagett R, Jayasundera KT, Heckenlively JR. T Helper 1 Cellular Immunity Toward Recoverin Is Enhanced in Patients With Active Autoimmune Retinopathy. Front Med (Lausanne) 2018; 5:249. [PMID: 30271775 PMCID: PMC6146138 DOI: 10.3389/fmed.2018.00249] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 08/16/2018] [Indexed: 01/01/2023] Open
Abstract
Autoimmune retinopathy (AIR) causes rapidly progressive vision loss that is treatable but often is confused with other forms of retinal degeneration including retinitis pigmentosa (RP). Measurement of anti-retinal antibodies (ARA) by Western blot is a commonly used laboratory assay that supports the diagnosis yet does not reflect current disease activity. To search for better diagnostic indicators, this study was designed to compare immune biomarkers and responses toward the retinal protein, recoverin, between newly diagnosed AIR patients, slow progressing RP patients and healthy controls. All individuals had measurable anti-recoverin IgG and IgM antibodies by ELISA regardless of disease status or Western blot results. Many AIR patients had elevated anti-recoverin IgG1 levels and a strong cellular response toward recoverin dominated by IFNγ. RP patients and controls responded to recoverin with a lower IFNγ response that was balanced by IL-10 production. Both AIR and RP patients displayed lower levels of total peripheral blood mononuclear cells that were due to reductions of CD4+ TH cells. A comparison of messenger RNA (mRNA) for immune-related genes in whole blood of AIR patients versus RP patients or controls indicated lower expression of ATG5 and PTPN22 and higher expression of several genes involved in TH cell signaling/transcription and adhesion. These data indicate that an immune response toward recoverin is normal in humans, but that in AIR patients the balance shifts dramatically toward higher IFNγ production and cellular activation.
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Affiliation(s)
- Steven K Lundy
- Department of Internal Medicine-Rheumatology, University of Michigan Medical School, Ann Arbor, MI, United States.,Graduate Training Program in Immunology, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Enayat Nikoopour
- Department of Internal Medicine-Rheumatology, University of Michigan Medical School, Ann Arbor, MI, United States.,Department of Ophthalmology and Visual Sciences-Kellogg Eye Center, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Athanasios J Karoukis
- Department of Ophthalmology and Visual Sciences-Kellogg Eye Center, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Ray Ohara
- Department of Internal Medicine-Rheumatology, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Mohammad I Othman
- Department of Ophthalmology and Visual Sciences-Kellogg Eye Center, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Rebecca Tagett
- Biostatistics Core Facility, University of Michigan Medical School, Ann Arbor, MI, United States
| | - K Thiran Jayasundera
- Department of Ophthalmology and Visual Sciences-Kellogg Eye Center, University of Michigan Medical School, Ann Arbor, MI, United States
| | - John R Heckenlively
- Department of Ophthalmology and Visual Sciences-Kellogg Eye Center, University of Michigan Medical School, Ann Arbor, MI, United States
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13
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Christoffers J. Diaminoterephthalate Fluorescence Dyes - Versatile Tools for Life Sciences and Materials Science. European J Org Chem 2018. [DOI: 10.1002/ejoc.201701447] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Jens Christoffers
- Institut für Chemie; Carl von Ossietzky Universität Oldenburg; 26111 Oldenburg Germany
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14
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Wallisch M, Sulmann S, Koch KW, Christoffers J. Bifunctional Diaminoterephthalate Fluorescent Dye as Probe for Cross-Linking Proteins. Chemistry 2017; 23:6535-6543. [DOI: 10.1002/chem.201700774] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Indexed: 01/05/2023]
Affiliation(s)
- Melanie Wallisch
- Institut für Chemie; Carl von Ossietzky-Universität Oldenburg; 26111 Oldenburg Germany
| | - Stefan Sulmann
- Biochemistry Group, Department of Neuroscience; Carl von Ossietzky-Universität Oldenburg; 26111 Oldenburg Germany
| | - Karl-Wilhelm Koch
- Biochemistry Group, Department of Neuroscience; Carl von Ossietzky-Universität Oldenburg; 26111 Oldenburg Germany
| | - Jens Christoffers
- Institut für Chemie; Carl von Ossietzky-Universität Oldenburg; 26111 Oldenburg Germany
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15
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Label-free quantification of calcium-sensor targeting to photoreceptor guanylate cyclase and rhodopsin kinase by backscattering interferometry. Sci Rep 2017; 7:45515. [PMID: 28361875 PMCID: PMC5374524 DOI: 10.1038/srep45515] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 02/28/2017] [Indexed: 01/26/2023] Open
Abstract
Quantification of protein binding to membrane proteins is challenging and a limited set of methods is available to study such systems. Here we employed backscattering interferometry (BSI), a free-solution label-free method with high sensitivity, to quantify the interaction of neuronal Ca2+-Sensor proteins with their targets operating in phototransduction. We tested direct binding of guanylate cyclase–activating proteins (GCAP1 and GCAP2) to their membrane target guanylate cyclase 1. The regulatory mechanism of GCAPs including their binding interface in the target is unresolved. Here we used a label-free, free-solution assay method based on BSI to determine binding constants of GCAP1 and GCAP2 to the full-length membrane-bound guanylate cyclase type 1. GCAP1 and GCAP2 bound to different regions on the target guanylate cyclase with submicromolar affinity (apparent KD-values of 663 ± 121 nM and 231 ± 63 nM for Ca2+-free GCAP1 and GCAP2, respectively). A guanylate cyclase construct containing the juxta-membrane and kinase homology domain harbored an exclusive binding site for GCAP1 with similar affinities as the full-length protein, whereas GCAP2 did not bind to this region. We provide a model in which GCAP1 and GCAP2 do not share a single binding site to the target, thus cannot exchange upon fluctuating Ca2+ levels.
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Koch KW, Dell'Orco D. Protein and Signaling Networks in Vertebrate Photoreceptor Cells. Front Mol Neurosci 2015; 8:67. [PMID: 26635520 PMCID: PMC4646965 DOI: 10.3389/fnmol.2015.00067] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 10/26/2015] [Indexed: 01/10/2023] Open
Abstract
Vertebrate photoreceptor cells are exquisite light detectors operating under very dim and bright illumination. The photoexcitation and adaptation machinery in photoreceptor cells consists of protein complexes that can form highly ordered supramolecular structures and control the homeostasis and mutual dependence of the secondary messengers cyclic guanosine monophosphate (cGMP) and Ca2+. The visual pigment in rod photoreceptors, the G protein-coupled receptor rhodopsin is organized in tracks of dimers thereby providing a signaling platform for the dynamic scaffolding of the G protein transducin. Illuminated rhodopsin is turned off by phosphorylation catalyzed by rhodopsin kinase (GRK1) under control of Ca2+-recoverin. The GRK1 protein complex partly assembles in lipid raft structures, where shutting off rhodopsin seems to be more effective. Re-synthesis of cGMP is another crucial step in the recovery of the photoresponse after illumination. It is catalyzed by membrane bound sensory guanylate cyclases (GCs) and is regulated by specific neuronal Ca2+-sensor proteins called guanylate cyclase-activating proteins (GCAPs). At least one GC (ROS-GC1) was shown to be part of a multiprotein complex having strong interactions with the cytoskeleton and being controlled in a multimodal Ca2+-dependent fashion. The final target of the cGMP signaling cascade is a cyclic nucleotide-gated (CNG) channel that is a hetero-oligomeric protein located in the plasma membrane and interacting with accessory proteins in highly organized microdomains. We summarize results and interpretations of findings related to the inhomogeneous organization of signaling units in photoreceptor outer segments.
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Affiliation(s)
- Karl-Wilhelm Koch
- Department of Neurosciences, Biochemistry Group, University of Oldenburg Oldenburg, Germany
| | - Daniele Dell'Orco
- Department of Neurological, Biomedical and Movement Sciences, Section of Biological Chemistry and Center for BioMedical Computing (CBMC), University of Verona Verona, Italy
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17
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Zernii EY, Nazipova AA, Gancharova OS, Kazakov AS, Serebryakova MV, Zinchenko DV, Tikhomirova NK, Senin II, Philippov PP, Permyakov EA, Permyakov SE. Light-induced disulfide dimerization of recoverin under ex vivo and in vivo conditions. Free Radic Biol Med 2015; 83:283-95. [PMID: 25772009 DOI: 10.1016/j.freeradbiomed.2015.03.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 01/10/2015] [Accepted: 03/02/2015] [Indexed: 12/13/2022]
Abstract
Despite vast knowledge of the molecular mechanisms underlying photochemical damage of photoreceptors, linked to progression of age-related macular degeneration, information on specific protein targets of the light-induced oxidative stress is scarce. Here, we demonstrate that prolonged intense illumination (halogen bulb, 1500 lx, 1-5 h) of mammalian eyes under ex vivo (cow) or in vivo (rabbit) conditions induces disulfide dimerization of recoverin, a Ca(2+)-dependent inhibitor of rhodopsin kinase. Western blotting and mass spectrometry analysis of retinal extracts reveals illumination time-dependent accumulation of disulfide homodimers of recoverin and its higher order disulfide cross-linked species, including a minor fraction of mixed disulfides with intracellular proteins (tubulins, etc.). Meanwhile, monomeric bovine recoverin remains mostly reduced. These effects are accompanied by accumulation of disulfide homodimers of visual arrestin. Histological studies demonstrate that the light-induced oxidation of recoverin and arrestin occurs in intact retina (illumination for 2 h), while illumination for 5 h is associated with damage of the photoreceptor layer. A comparison of ex vivo levels of disulfide homodimers of bovine recoverin with redox dependence of its in vitro thiol-disulfide equilibrium (glutathione redox pair) gives the lowest estimate of redox potential in rod outer segments under illumination from -160 to -155 mV. Chemical crosslinking and dynamic light scattering data demonstrate an increased propensity of disulfide dimer of bovine recoverin to multimerization/aggregation. Overall, the oxidative stress caused by the prolonged intense illumination of retina might affect rhodopsin desensitization via concerted disulfide dimerization of recoverin and arrestin. The developed herein models of eye illumination are useful for studies of the light-induced thiol oxidation of visual proteins.
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Affiliation(s)
- Evgeni Yu Zernii
- Department of Cell Signaling, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992 Russia.
| | - Aliya A Nazipova
- Protein Research Group, Institute for Biological Instrumentation of the Russian Academy of Sciences, Pushchino, Moscow region, 142290 Russia
| | - Olga S Gancharova
- Department of Cell Signaling, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992 Russia
| | - Alexey S Kazakov
- Protein Research Group, Institute for Biological Instrumentation of the Russian Academy of Sciences, Pushchino, Moscow region, 142290 Russia
| | - Marina V Serebryakova
- Department of Cell Signaling, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992 Russia
| | - Dmitry V Zinchenko
- Branch of Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Pushchino, Moscow region, 142290 Russia
| | - Natalya K Tikhomirova
- Department of Cell Signaling, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992 Russia
| | - Ivan I Senin
- Department of Cell Signaling, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992 Russia
| | - Pavel P Philippov
- Department of Cell Signaling, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992 Russia
| | - Eugene A Permyakov
- Protein Research Group, Institute for Biological Instrumentation of the Russian Academy of Sciences, Pushchino, Moscow region, 142290 Russia; Department of Biomedical Engineering, Pushchino State Institute of Natural Sciences, Pushchino, Moscow region, 142290 Russia
| | - Sergei E Permyakov
- Protein Research Group, Institute for Biological Instrumentation of the Russian Academy of Sciences, Pushchino, Moscow region, 142290 Russia; Department of Biomedical Engineering, Pushchino State Institute of Natural Sciences, Pushchino, Moscow region, 142290 Russia
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18
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Zernii EY, Grigoriev II, Nazipova AA, Scholten A, Kolpakova TV, Zinchenko DV, Kazakov AS, Senin II, Permyakov SE, Dell'Orco D, Philippov PP, Koch KW. Regulatory function of the C-terminal segment of guanylate cyclase-activating protein 2. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2015; 1854:1325-37. [PMID: 26001899 DOI: 10.1016/j.bbapap.2015.05.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2015] [Revised: 04/22/2015] [Accepted: 05/13/2015] [Indexed: 12/13/2022]
Abstract
Neuronal responses to Ca2+-signals are provided by EF-hand-type neuronal Ca2+-sensor (NCS) proteins, which have similar core domains containing Ca2+-binding and target-recognizing sites. NCS proteins vary in functional specificity, probably depending on the structure and conformation of their non-conserved C-terminal segments. Here, we investigated the role of the C-terminal segment in guanylate cyclase activating protein-2, GCAP2, an NCS protein controlling the Ca2+-dependent regulation of photoreceptor guanylate cyclases. We obtained two chimeric proteins by exchanging C-terminal segments between GCAP2 and its photoreceptor homolog recoverin, a Ca2+-sensor controlling rhodopsin kinase (RK) activity. The exchange affected neither the structural integrity of GCAP2 and recoverin nor the Ca2+-sensitivity of GCAP2. Intrinsic fluorescence, circular dichroism, biochemical studies and hydrophobic dye probing revealed Ca2+-dependent conformational transition of the C-terminal segment of GCAP2 occurring in the molecular environment of both proteins. In Ca2+-GCAP2, the C-terminal segment was constrained and its replacement provided the protein with approximately two-fold inhibitory activity towards RK, suggesting that the segment contributes to specific target recognition by interfering with RK-binding. Upon Ca2+-release, it became less constrained and more available for phosphorylation by cyclic nucleotide-dependent protein kinase. The transition from the Ca2+-bound to the apo-state exposed hydrophobic sites in GCAP2, and was associated with its activating function without affecting its dimerization. The released C-terminal segment participated further in photoreceptor membrane binding making it sensitive to phosphorylation. Thus, the C-terminal segment in GCAP2 confers target selectivity, facilitates membrane binding and provides sensitivity of the membrane localization of the protein to phosphorylation by signaling kinases.
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Affiliation(s)
- Evgeni Yu Zernii
- Department of Cell Signaling, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992 Russia
| | - Ilya I Grigoriev
- Department of Cell Signaling, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992 Russia
| | - Aliya A Nazipova
- Protein Research Group, Institute for Biological Instrumentation of the Russian Academy of Sciences, Pushchino, Moscow region, 142290 Russia
| | - Alexander Scholten
- Department of Neurosciences, Biochemistry Group, University of Oldenburg, Oldenburg, 26111 Germany
| | - Tatiana V Kolpakova
- Department of Cell Signaling, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992 Russia
| | - Dmitry V Zinchenko
- Branch of Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Pushchino, Moscow region, 142290 Russia
| | - Alexey S Kazakov
- Protein Research Group, Institute for Biological Instrumentation of the Russian Academy of Sciences, Pushchino, Moscow region, 142290 Russia
| | - Ivan I Senin
- Department of Cell Signaling, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992 Russia
| | - Sergei E Permyakov
- Protein Research Group, Institute for Biological Instrumentation of the Russian Academy of Sciences, Pushchino, Moscow region, 142290 Russia
| | - Daniele Dell'Orco
- Department of Life Sciences and Reproduction, Section of Biological Chemistry and Center for BioMedical Computing, University of Verona, Verona, 37134 Italy
| | - Pavel P Philippov
- Department of Cell Signaling, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992 Russia
| | - Karl-W Koch
- Department of Neurosciences, Biochemistry Group, University of Oldenburg, Oldenburg, 26111 Germany.
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Invergo BM, Dell'Orco D, Montanucci L, Koch KW, Bertranpetit J. A comprehensive model of the phototransduction cascade in mouse rod cells. MOLECULAR BIOSYSTEMS 2014; 10:1481-9. [PMID: 24675755 DOI: 10.1039/c3mb70584f] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Vertebrate visual phototransduction is perhaps the most well-studied G-protein signaling pathway. A wealth of available biochemical and electrophysiological data has resulted in a rich history of mathematical modeling of the system. However, while the most comprehensive models have relied upon amphibian biochemical and electrophysiological data, modern research typically employs mammalian species, particularly mice, which exhibit significantly faster signaling dynamics. In this work, we present an adaptation of a previously published, comprehensive model of amphibian phototransduction that can produce quantitatively accurate simulations of the murine photoresponse. We demonstrate the ability of the model to predict responses to a wide range of stimuli and under a variety of mutant conditions. Finally, we employ the model to highlight a likely unknown mechanism related to the interaction between rhodopsin and rhodopsin kinase.
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Affiliation(s)
- Brandon M Invergo
- IBE - Institute of Evolutionary Biology (CSIC-Universitat Pompeu Fabra), CEXS-UPF-PRBB, Barcelona, Catalonia, Spain
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20
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Lim S, Dizhoor AM, Ames JB. Structural diversity of neuronal calcium sensor proteins and insights for activation of retinal guanylyl cyclase by GCAP1. Front Mol Neurosci 2014; 7:19. [PMID: 24672427 PMCID: PMC3956117 DOI: 10.3389/fnmol.2014.00019] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 02/27/2014] [Indexed: 01/08/2023] Open
Abstract
Neuronal calcium sensor (NCS) proteins, a sub-branch of the calmodulin superfamily, are expressed in the brain and retina where they transduce calcium signals and are genetically linked to degenerative diseases. The amino acid sequences of NCS proteins are highly conserved but their physiological functions are quite different. Retinal recoverin controls Ca2+-dependent inactivation of light-excited rhodopsin during phototransduction, guanylyl cyclase activating proteins 1 and 2 (GCAP1 and GCAP2) promote Ca2+-dependent activation of retinal guanylyl cyclases, and neuronal frequenin (NCS-1) modulates synaptic activity and neuronal secretion. Here we review the molecular structures of myristoylated forms of NCS-1, recoverin, and GCAP1 that all look very different, suggesting that the attached myristoyl group helps to refold these highly homologous proteins into different three-dimensional folds. Ca2+-binding to both recoverin and NCS-1 cause large protein conformational changes that ejects the covalently attached myristoyl group into the solvent exterior and promotes membrane targeting (Ca2+-myristoyl switch). The GCAP proteins undergo much smaller Ca2+-induced conformational changes and do not possess a Ca2+-myristoyl switch. Recent structures of GCAP1 in both its activator and Ca2+-bound inhibitory states will be discussed to understand structural determinants that control their Ca2+-dependent activation of retinal guanylyl cyclases.
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Affiliation(s)
- Sunghyuk Lim
- Department of Chemistry, University of California at Davis Davis, CA, USA
| | - Alexander M Dizhoor
- Basic Sciences, Pennsylvania College of Optometry, Salus University Elkins Park, PA, USA
| | - James B Ames
- Department of Chemistry, University of California at Davis Davis, CA, USA
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21
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Zernii EY, Zinchenko DV, Vladimirov VI, Grigoriev II, Skorikova EE, Baksheeva VE, Lipkin VM, Philippov PP, Senin II. Ca2+-dependent regulatory activity of recoverin in photoreceptor raft structures: The role of caveolin-1. BIOCHEMISTRY MOSCOW SUPPLEMENT SERIES A-MEMBRANE AND CELL BIOLOGY 2014. [DOI: 10.1134/s1990747813050255] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Myers WK, Xu X, Li C, Lagerstedt JO, Budamagunta MS, Voss JC, Britt RD, Ames JB. Double electron-electron resonance probes Ca²⁺-induced conformational changes and dimerization of recoverin. Biochemistry 2013; 52:5800-8. [PMID: 23906368 DOI: 10.1021/bi400538w] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Recoverin, a member of the neuronal calcium sensor (NCS) branch of the calmodulin superfamily, is expressed in retinal photoreceptor cells and serves as a calcium sensor in vision. Ca²⁺-induced conformational changes in recoverin cause extrusion of its covalently attached myristate (termed Ca²⁺-myristoyl switch) that promotes translocation of recoverin to disk membranes during phototransduction in retinal rod cells. Here we report double electron-electron resonance (DEER) experiments on recoverin that probe Ca²⁺-induced changes in distance as measured by the dipolar coupling between spin-labels strategically positioned at engineered cysteine residues on the protein surface. The DEER distance between nitroxide spin-labels attached at C39 and N120C is 2.5 ± 0.1 nm for Ca²⁺-free recoverin and 3.7 ± 0.1 nm for Ca²⁺-bound recoverin. An additional DEER distance (5-6 nm) observed for Ca²⁺-bound recoverin may represent an intermolecular distance between C39 and N120. ¹⁵N NMR relaxation analysis and CW-EPR experiments both confirm that Ca²⁺-bound recoverin forms a dimer at protein concentrations above 100 μM, whereas Ca²⁺-free recoverin is monomeric. We propose that Ca²⁺-induced dimerization of recoverin at the disk membrane surface may play a role in regulating Ca²⁺-dependent phosphorylation of dimeric rhodopsin. The DEER approach will be useful for elucidating dimeric structures of NCS proteins in general for which Ca²⁺-induced dimerization is functionally important but not well understood.
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Affiliation(s)
- William K Myers
- Department of Chemistry, University of California, Davis, California 95616, United States
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23
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Invergo BM, Montanucci L, Koch KW, Bertranpetit J, Dell'orco D. Exploring the rate-limiting steps in visual phototransduction recovery by bottom-up kinetic modeling. Cell Commun Signal 2013; 11:36. [PMID: 23693153 PMCID: PMC3732082 DOI: 10.1186/1478-811x-11-36] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Accepted: 05/09/2013] [Indexed: 01/20/2023] Open
Abstract
Background Phototransduction in vertebrate photoreceptor cells represents a paradigm of signaling pathways mediated by G-protein-coupled receptors (GPCRs), which share common modules linking the initiation of the cascade to the final response of the cell. In this work, we focused on the recovery phase of the visual photoresponse, which is comprised of several interacting mechanisms. Results We employed current biochemical knowledge to investigate the response mechanisms of a comprehensive model of the visual phototransduction pathway. In particular, we have improved the model by implementing a more detailed representation of the recoverin (Rec)-mediated calcium feedback on rhodopsin kinase and including a dynamic arrestin (Arr) oligomerization mechanism. The model was successfully employed to investigate the rate limiting steps in the recovery of the rod photoreceptor cell after illumination. Simulation of experimental conditions in which the expression levels of rhodospin kinase (RK), of the regulator of the G-protein signaling (RGS), of Arr and of Rec were altered individually or in combination revealed severe kinetic constraints to the dynamics of the overall network. Conclusions Our simulations confirm that RGS-mediated effector shutdown is the rate-limiting step in the recovery of the photoreceptor and show that the dynamic formation and dissociation of Arr homodimers and homotetramers at different light intensities significantly affect the timing of rhodopsin shutdown. The transition of Arr from its oligomeric storage forms to its monomeric form serves to temper its availability in the functional state. Our results may explain the puzzling evidence that overexpressing RK does not influence the saturation time of rod cells at bright light stimuli. The approach presented here could be extended to the study of other GPCR signaling pathways.
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Affiliation(s)
- Brandon M Invergo
- Department of Life Sciences and Reproduction, Section of Biological Chemistry and Center for BioMedical Computing (CBMC), University of Verona, Strada le Grazie 8, 37134, Verona, Italy.
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Ames JB, Lim S. Molecular structure and target recognition of neuronal calcium sensor proteins. BIOCHIMICA ET BIOPHYSICA ACTA 2012; 1820:1205-13. [PMID: 22020049 PMCID: PMC3266469 DOI: 10.1016/j.bbagen.2011.10.003] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Revised: 10/06/2011] [Accepted: 10/07/2011] [Indexed: 02/06/2023]
Abstract
BACKGROUND Neuronal calcium sensor (NCS) proteins, a sub-branch of the calmodulin superfamily, are expressed in the brain and retina where they transduce calcium signals and are genetically linked to degenerative diseases. The amino acid sequences of NCS proteins are highly conserved but their physiological functions are quite distinct. Retinal recoverin and guanylate cyclase activating proteins (GCAPs) both serve as calcium sensors in retinal rod cells, neuronal frequenin (NCS1) modulate synaptic activity and neuronal secretion, K+ channel interacting proteins (KChIPs) regulate ion channels to control neuronal excitability, and DREAM (KChIP3) is a transcriptional repressor that regulates neuronal gene expression. SCOPE OF REVIEW Here we review the molecular structures of myristoylated forms of NCS1, recoverin, and GCAP1 that all look very different, suggesting that the sequestered myristoyl group helps to refold these highly homologous proteins into very different structures. The molecular structure of NCS target complexes have been solved for recoverin bound to rhodopsin kinase, NCS-1 bound to phosphatidylinositol 4-kinase, and KChIP1 bound to A-type K+ channels. MAJOR CONCLUSIONS We propose the idea that N-terminal myristoylation is critical for shaping each NCS family member into a unique structure, which upon Ca2+-induced extrusion of the myristoyl group exposes a unique set of previously masked residues, thereby exposing a distinctive ensemble of hydrophobic residues to associate specifically with a particular physiological target. This article is part of a Special Issue entitled Biochemical, biophysical and genetic approaches to intracellular calcium signaling.
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Affiliation(s)
- James B Ames
- University of California, Davis Department of Chemistry, Davis, CA 95616, USa.
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25
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Nevet MJ, Vekslin S, Dizhoor AM, Olshevskaya EV, Tidhar R, Futerman AH, Ben-Yosef T. Ceramide kinase-like (CERKL) interacts with neuronal calcium sensor proteins in the retina in a cation-dependent manner. Invest Ophthalmol Vis Sci 2012; 53:4565-74. [PMID: 22678504 DOI: 10.1167/iovs.12-9770] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE CERKL encodes for a ceramide kinase (CERK)-like protein. CERKL mutations are associated with severe retinal degeneration. Several studies have been conducted to prove a biochemical similarity between CERK and CERKL enzymatic activities. However, so far there has been no evidence that CERKL phosphorylates ceramide or any other lipid substrate in vitro or in vivo. The purpose of this work was to characterize CERKL's function by identification of CERKL-interacting proteins in the mammalian retina. METHODS CERKL-interacting proteins were identified implementing the Ras-recruitment system (RRS) on a bovine retina cDNA library. Co-immunoprecipitation (co-IP) in transfected cells and in photoreceptor outer segments was used to verify the identified interactions. Serial deletion constructs were used to map the interacting sites. CERKL's kinase activity was tested by a CERK activity assay. RESULTS We identified an interaction between CERKL and several neuronal calcium sensor (NCS) proteins, including guanylate cyclase activating protein 1 (GCAP1), GCAP2, and recoverin. These interactions were confirmed by co-IP experiments in transfected mammalian cells. Moreover, the interaction between endogenous CERKL and GCAP2 was confirmed by co-IP in photoreceptor outer segments. We found that CERKL-GCAP interaction is cation dependent and is mediated by CERKL's N-terminal region and by GCAPs cation-binding domains (EF-hands 2-4). CONCLUSIONS This study, which is the first to describe the interactions of CERKL with other retinal proteins, links CERKL to proteins involved in the photoresponse and Ca(2+) signaling, providing important clues for future research required in this direction.
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Affiliation(s)
- Mariela J Nevet
- Department of Genetics and The Rappaport Family Institute for Research in the Medical Sciences, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
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Navarro G, Hradsky J, Lluís C, Casadó V, McCormick PJ, Kreutz MR, Mikhaylova M. NCS-1 associates with adenosine A(2A) receptors and modulates receptor function. Front Mol Neurosci 2012; 5:53. [PMID: 22529776 PMCID: PMC3328853 DOI: 10.3389/fnmol.2012.00053] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Accepted: 04/02/2012] [Indexed: 11/13/2022] Open
Abstract
Modulation of G protein-coupled receptor (GPCR) signaling by local changes in intracellular calcium concentration is an established function of Calmodulin (CaM) which is known to interact with many GPCRs. Less is known about the functional role of the closely related neuronal EF-hand Ca2+-sensor proteins that frequently associate with CaM targets with different functional outcome. In the present study we aimed to investigate if a target of CaM—the A2A adenosine receptor is able to associate with two other neuronal calcium binding proteins (nCaBPs), namely NCS-1 and caldendrin. Using bioluminescence resonance energy transfer (BRET) and co-immunoprecipitation experiments we show the existence of A2A—NCS-1 complexes in living cells whereas caldendrin did not associate with A2A receptors under the conditions tested. Interestingly, NCS-1 binding modulated downstream A2A receptor intracellular signaling in a Ca2+-dependent manner. Taken together this study provides further evidence that neuronal Ca2+-sensor proteins play an important role in modulation of GPCR signaling.
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Affiliation(s)
- Gemma Navarro
- Faculty of Biology, Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas and Department of Biochemistry and Molecular Biology, University of Barcelona Barcelona, Spain
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Grigoriev II, Senin II, Tikhomirova NK, Komolov KE, Permyakov SE, Zernii EY, Koch KW, Philippov PP. Synergetic effect of recoverin and calmodulin on regulation of rhodopsin kinase. Front Mol Neurosci 2012; 5:28. [PMID: 22408603 PMCID: PMC3296934 DOI: 10.3389/fnmol.2012.00028] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Accepted: 02/17/2012] [Indexed: 01/24/2023] Open
Abstract
Phosphorylation of photoactivated rhodopsin by rhodopsin kinase (RK or GRK1), a first step of the phototransduction cascade turnoff, is under the control of Ca2+/recoverin. Here, we demonstrate that calmodulin, a ubiquitous Ca2+-sensor, can inhibit RK, though less effectively than recoverin does. We have utilized the surface plasmon resonance technology to map the calmodulin binding site in the RK molecule. Calmodulin does not interact with the recoverin-binding site within amino acid residues M1-S25 of the enzyme. Instead, the high affinity calmodulin binding site is localized within a stretch of amino acid residues V150-K175 in the N-terminal regulatory region of RK. Moreover, the inhibitory effect of calmodulin and recoverin on RK activity is synergetic, which is in agreement with the existence of separate binding sites for each Ca2+-sensing protein. The synergetic inhibition of RK by both Ca2+-sensors occurs over a broader range of Ca2+-concentration than by recoverin alone, indicating increased Ca2+-sensitivity of RK regulation in the presence of both Ca2+-sensors. Taken together, our data suggest that RK regulation by calmodulin in photoreceptor cells could complement the well-known inhibitory effect of recoverin on RK.
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Affiliation(s)
- Ilya I Grigoriev
- Department of Cell Signaling, A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University Moscow, Russia
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28
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Ames JB, Lim S, Ikura M. Molecular structure and target recognition of neuronal calcium sensor proteins. Front Mol Neurosci 2012; 5:10. [PMID: 22363261 PMCID: PMC3275791 DOI: 10.3389/fnmol.2012.00010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Accepted: 01/26/2012] [Indexed: 01/19/2023] Open
Abstract
Neuronal calcium sensor (NCS) proteins, a sub-branch of the EF-hand superfamily, are expressed in the brain and retina where they transduce calcium signals and are genetically linked to degenerative diseases. The amino acid sequences of NCS proteins are highly conserved but their physiological functions are quite distinct. Retinal recoverin and guanylate cyclase activating proteins (GCAPs) both serve as calcium sensors in retinal rod cells, neuronal frequenin (NCS1) modulates synaptic activity and neuronal secretion, K+ channel interacting proteins (KChIPs) regulate ion channels to control neuronal excitability, and DREAM (KChIP3) is a transcriptional repressor that regulates neuronal gene expression. Here we review the molecular structures of myristoylated forms of NCS1, recoverin, and GCAP1 that all look very different, suggesting that the sequestered myristoyl group helps to refold these highly homologous proteins into very different structures. The molecular structure of NCS target complexes have been solved for recoverin bound to rhodopsin kinase (RK), NCS-1 bound to phosphatidylinositol 4-kinase, and KChIP1 bound to A-type K+ channels. We propose that N-terminal myristoylation is critical for shaping each NCS family member into a different structure, which upon Ca2+-induced extrusion of the myristoyl group exposes a unique set of previously masked residues that interact with a particular physiological target.
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Affiliation(s)
- James B Ames
- Department of Chemistry, University of California, Davis CA, USA
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29
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Burgoyne RD, Haynes LP. Understanding the physiological roles of the neuronal calcium sensor proteins. Mol Brain 2012; 5:2. [PMID: 22269068 PMCID: PMC3271974 DOI: 10.1186/1756-6606-5-2] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Accepted: 01/23/2012] [Indexed: 01/22/2023] Open
Abstract
Calcium signalling plays a crucial role in the control of neuronal function and plasticity. Changes in neuronal Ca2+ concentration are detected by Ca2+-binding proteins that can interact with and regulate target proteins to modify their function. Members of the neuronal calcium sensor (NCS) protein family have multiple non-redundant roles in the nervous system. Here we review recent advances in the understanding of the physiological roles of the NCS proteins and the molecular basis for their specificity.
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Affiliation(s)
- Robert D Burgoyne
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, University of Liverpool, Liverpool, UK.
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30
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Yanamala N, Gardner E, Riciutti A, Klein-Seetharaman J. The cytoplasmic rhodopsin-protein interface: potential for drug discovery. Curr Drug Targets 2012; 13:3-14. [PMID: 21777183 PMCID: PMC3275648 DOI: 10.2174/138945012798868461] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2010] [Revised: 02/08/2011] [Accepted: 02/10/2011] [Indexed: 01/20/2023]
Abstract
The mammalian dim-light photoreceptor rhodopsin is a prototypic G protein coupled receptor (GPCR), interacting with the G protein, transducin, rhodopsin kinase, and arrestin. All of these proteins interact with rhodopsin at its cytoplasmic surface. Structural and modeling studies have provided in-depth descriptions of the respective interfaces. Overlap and thus competition for binding surfaces is a major regulatory mechanism for signal processing. Recently, it was found that the same surface is also targeted by small molecules. These ligands can directly interfere with the binding and activation of the proteins of the signal transduction cascade, but they can also allosterically modulate the retinal ligand binding pocket. Because the pocket that is targeted contains residues that are highly conserved across Class A GPCRs, these findings imply that it may be possible to target multiple GPCRs with the same ligand(s). This is desirable for example in complex diseases such as cancer where multiple GPCRs participate in the disease networks.
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Affiliation(s)
- Naveena Yanamala
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA
| | - Eric Gardner
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA
| | - Alec Riciutti
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA
| | - Judith Klein-Seetharaman
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA
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31
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Biophysical investigation of retinal calcium sensor function. Biochim Biophys Acta Gen Subj 2011; 1820:1228-33. [PMID: 22020050 DOI: 10.1016/j.bbagen.2011.10.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Revised: 10/05/2011] [Accepted: 10/06/2011] [Indexed: 11/22/2022]
Abstract
BACKGROUND Neuronal calcium sensor proteins represent a subgroup of the family of EF-hand calcium binding proteins. Members of this subgroup are the guanylate cyclase-activating proteins and recoverin, which operate as important calcium sensors in retinal photoreceptor cells. Physiological and biochemical data indicate that these proteins participate in shaping the photoreceptor light response. SCOPE OF REVIEW Biophysical methods have been widely applied to investigate the molecular properties of retinal calcium binding proteins like the guanylate cyclase-activating proteins and recoverin. Properties include the determination of calcium affinities by isotope techniques and spectroscopical approaches. Conformational changes are investigated for example by tryptophan fluorescence emission. A special focus of this review is laid on a new experimental approach to study conformational changes in calcium binding proteins by surface plasmon resonance spectroscopy. In addition this technique has been employed for measuring the calcium-dependent binding of calcium sensors to membranes. MAJOR CONCLUSIONS Biophysical approaches provide valuable information about key properties of calcium sensor proteins involved in intracellular signalling. Parameters of their molecular properties like calcium binding and conformational changes help to define their physiological role derived from cellular, genetic or physiological studies. GENERAL SIGNIFICANCE Calcium is an important second messenger in intracellular signaling. Calcium signals are propagated via calcium binding proteins that are able to discriminate between incremental differences in intracellular calcium and that regulate their targets with high precision and specificity. This article is part of a Special Issue entitled Biochemical, biophysical and genetic approaches to intracellular calcium signalling.
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32
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Gurevich EV, Tesmer JJG, Mushegian A, Gurevich VV. G protein-coupled receptor kinases: more than just kinases and not only for GPCRs. Pharmacol Ther 2011; 133:40-69. [PMID: 21903131 DOI: 10.1016/j.pharmthera.2011.08.001] [Citation(s) in RCA: 319] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Accepted: 08/01/2011] [Indexed: 12/24/2022]
Abstract
G protein-coupled receptor (GPCR) kinases (GRKs) are best known for their role in homologous desensitization of GPCRs. GRKs phosphorylate activated receptors and promote high affinity binding of arrestins, which precludes G protein coupling. GRKs have a multidomain structure, with the kinase domain inserted into a loop of a regulator of G protein signaling homology domain. Unlike many other kinases, GRKs do not need to be phosphorylated in their activation loop to achieve an activated state. Instead, they are directly activated by docking with active GPCRs. In this manner they are able to selectively phosphorylate Ser/Thr residues on only the activated form of the receptor, unlike related kinases such as protein kinase A. GRKs also phosphorylate a variety of non-GPCR substrates and regulate several signaling pathways via direct interactions with other proteins in a phosphorylation-independent manner. Multiple GRK subtypes are present in virtually every animal cell, with the highest expression levels found in neurons, with their extensive and complex signal regulation. Insufficient or excessive GRK activity was implicated in a variety of human disorders, ranging from heart failure to depression to Parkinson's disease. As key regulators of GPCR-dependent and -independent signaling pathways, GRKs are emerging drug targets and promising molecular tools for therapy. Targeted modulation of expression and/or of activity of several GRK isoforms for therapeutic purposes was recently validated in cardiac disorders and Parkinson's disease.
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Affiliation(s)
- Eugenia V Gurevich
- Department of Pharmacology, Vanderbilt University, 2200 Pierce Avenue, Preston Research Building, Rm. 454, Nashville, TN 37232, United States.
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Mikhaylova M, Hradsky J, Kreutz MR. Between promiscuity and specificity: novel roles of EF-hand calcium sensors in neuronal Ca2+ signalling. J Neurochem 2011; 118:695-713. [PMID: 21722133 DOI: 10.1111/j.1471-4159.2011.07372.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In recent years, substantial progress has been made towards an understanding of the physiological function of EF-hand calcium sensor proteins of the Calmodulin (CaM) superfamily in neurons. This deeper appreciation is based on the identification of novel target interactions, structural studies and the discovery of novel signalling mechanisms in protein trafficking and synaptic plasticity, in which CaM-like sensor proteins appear to play a role. However, not all interactions are of plausible physiological relevance and in many cases it is not yet clear how the CaM signaling network relates to the proposed function of other EF-hand sensors. In this review, we will summarize these findings and address some of the open questions on the functional role of EF-hand calcium binding proteins in neurons.
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Affiliation(s)
- Marina Mikhaylova
- PG Neuroplasticity, Leibniz-Institute for Neurobiology, Magdeburg, Germany
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34
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Involvement of the recoverin C-terminal segment in recognition of the target enzyme rhodopsin kinase. Biochem J 2011; 435:441-50. [DOI: 10.1042/bj20110013] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
NCS (neuronal Ca2+ sensor) proteins belong to a family of calmodulin-related EF-hand Ca2+-binding proteins which, in spite of a high degree of structural similarity, are able to selectively recognize and regulate individual effector enzymes in a Ca2+-dependent manner. NCS proteins vary at their C-termini, which could therefore serve as structural control elements providing specific functions such as target recognition or Ca2+ sensitivity. Recoverin, an NCS protein operating in vision, regulates the activity of rhodopsin kinase, GRK1, in a Ca2+-dependent manner. In the present study, we investigated a series of recoverin forms that were mutated at the C-terminus. Using pull-down assays, surface plasmon resonance spectroscopy and rhodopsin phosphorylation assays, we demonstrated that truncation of recoverin at the C-terminus significantly reduced the affinity of recoverin for rhodopsin kinase. Site-directed mutagenesis of single amino acids in combination with structural analysis and computational modelling of the recoverin–kinase complex provided insight into the protein–protein interface between the kinase and the C-terminus of recoverin. Based on these results we suggest that Phe3 from the N-terminal helix of rhodopsin kinase and Lys192 from the C-terminal segment of recoverin form a cation–π interaction pair which is essential for target recognition by recoverin. Taken together, the results of the present study reveal a novel rhodopsin-kinase-binding site within the C-terminal region of recoverin, and highlights its significance for target recognition and regulation.
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35
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Fries R, Reddy PP, Mikhaylova M, Haverkamp S, Wei T, Müller M, Kreutz MR, Koch KW. Dynamic cellular translocation of caldendrin is facilitated by the Ca2+-myristoyl switch of recoverin. J Neurochem 2010; 113:1150-62. [PMID: 20236386 DOI: 10.1111/j.1471-4159.2010.06676.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Caldendrin and recoverin are Ca(2+)-sensor proteins operating in neuronal systems. In a search for novel binding partners of recoverin, we employed an affinity column and identified caldendrin as a possible interaction partner. Caldendrin and recoverin co-localized in the retina in a subset of bipolar cells and in the pineal gland as revealed by immunofluorescence studies. The binding process was controlled by Ca(2+) as revealed by pull-down assays, and surface plasmon resonance studies. Importantly, caldendrin existed as a Ca(2+)-independent homodimer whereas a complex of recoverin and caldendrin formed with low to moderate affinity in the presence of Ca(2+). Co-transfection of COS-7 cells with plasmids harboring the gene for fluorescently labeled recoverin and caldendrin was used to study the cellular distribution by time-lapse fluorescence microscopy. Apparently, the increase of intracellular Ca(2+) facilitates the translocation of caldendrin to intracellular membranes, which is under control of complex formation with recoverin.
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Affiliation(s)
- Ramona Fries
- Biochemistry group, Institute of Biology and Environmental Science, Faculty V, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
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