1
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Zang J, Neuhauss SCF. Biochemistry and physiology of zebrafish photoreceptors. Pflugers Arch 2021; 473:1569-1585. [PMID: 33598728 PMCID: PMC8370914 DOI: 10.1007/s00424-021-02528-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 01/25/2021] [Accepted: 01/28/2021] [Indexed: 02/06/2023]
Abstract
All vertebrates share a canonical retina with light-sensitive photoreceptors in the outer retina. These photoreceptors are of two kinds: rods and cones, adapted to low and bright light conditions, respectively. They both show a peculiar morphology, with long outer segments, comprised of ordered stacks of disc-shaped membranes. These discs host numerous proteins, many of which contribute to the visual transduction cascade. This pathway converts the light stimulus into a biological signal, ultimately modulating synaptic transmission. Recently, the zebrafish (Danio rerio) has gained popularity for studying the function of vertebrate photoreceptors. In this review, we introduce this model system and its contribution to our understanding of photoreception with a focus on the cone visual transduction cascade.
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Affiliation(s)
- Jingjing Zang
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrase 190, CH - 8057, Zürich, Switzerland
| | - Stephan C F Neuhauss
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrase 190, CH - 8057, Zürich, Switzerland.
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2
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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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3
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Abbas S, Marino V, Dell’Orco D, Koch KW. Molecular Recognition of Rhodopsin Kinase GRK1 and Recoverin Is Tuned by Switching Intra- and Intermolecular Electrostatic Interactions. Biochemistry 2019; 58:4374-4385. [DOI: 10.1021/acs.biochem.9b00846] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Seher Abbas
- Department of Neuroscience, Division of Biochemistry, University of Oldenburg, 26111 Oldenburg, Germany
| | - Valerio Marino
- Department of Neurosciences, 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, 56126 Pisa, Italy
| | - Daniele Dell’Orco
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, 37134 Verona, Italy
| | - Karl-Wilhelm Koch
- Department of Neuroscience, Division of Biochemistry, University of Oldenburg, 26111 Oldenburg, Germany
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4
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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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Permyakov SE, Vologzhannikova AS, Nemashkalova EL, Kazakov AS, Denesyuk AI, Denessiouk K, Baksheeva VE, Zamyatnin AA, Zernii EY, Uversky VN, Permyakov EA. Experimental Insight into the Structural and Functional Roles of the 'Black' and 'Gray' Clusters in Recoverin, a Calcium Binding Protein with Four EF-Hand Motifs. Molecules 2019; 24:E2494. [PMID: 31288444 PMCID: PMC6650976 DOI: 10.3390/molecules24132494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 07/03/2019] [Accepted: 07/07/2019] [Indexed: 11/17/2022] Open
Abstract
Recently, we have found that calcium binding proteins of the EF-hand superfamily (i.e., a large family of proteins containing helix-loop-helix calcium binding motif or EF-hand) contain two types of conserved clusters called cluster I ('black' cluster) and cluster II ('grey' cluster), which provide a supporting scaffold for the Ca2+ binding loops and contribute to the hydrophobic core of the EF-hand domains. Cluster I is more conservative and mostly incorporates aromatic amino acids, whereas cluster II includes a mix of aromatic, hydrophobic, and polar amino acids of different sizes. Recoverin is EF-hand Ca2+-binding protein containing two 'black' clusters comprised of F35, F83, Y86 (N-terminal domain) and F106, E169, F172 (C-terminal domain) as well as two 'gray' clusters comprised of F70, Q46, F49 (N-terminal domain) and W156, K119, V122 (C-terminal domain). To understand a role of these residues in structure and function of human recoverin, we sequentially substituted them for alanine and studied the resulting mutants by a set of biophysical methods. Under metal-free conditions, the 'black' clusters mutants (except for F35A and E169A) were characterized by an increase in the α-helical content, whereas the 'gray' cluster mutants (except for K119A) exhibited the opposite behavior. By contrast, in Ca2+-loaded mutants the α-helical content was always elevated. In the absence of calcium, the substitutions only slightly affected multimerization of recoverin regardless of their localization (except for K119A). Meanwhile, in the presence of calcium mutations in N-terminal domain of the protein significantly suppressed this process, indicating that surface properties of Ca2+-bound recoverin are highly affected by N-terminal cluster residues. The substitutions in C-terminal clusters generally reduced thermal stability of recoverin with F172A ('black' cluster) as well as W156A and K119A ('gray' cluster) being the most efficacious in this respect. In contrast, the mutations in the N-terminal clusters caused less pronounced differently directed changes in thermal stability of the protein. The substitutions of F172, W156, and K119 in C-terminal domain of recoverin together with substitution of Q46 in its N-terminal domain provoked significant but diverse changes in free energy associated with Ca2+ binding to the protein: the mutant K119A demonstrated significantly improved calcium binding, whereas F172A and W156A showed decrease in the calcium affinity and Q46A exhibited no ion coordination in one of the Ca2+-binding sites. The most of the N-terminal clusters mutations suppressed membrane binding of recoverin and its inhibitory activity towards rhodopsin kinase (GRK1). Surprisingly, the mutant W156A aberrantly activated rhodopsin phosphorylation regardless of the presence of calcium. Taken together, these data confirm the scaffolding function of several cluster-forming residues and point to their critical role in supporting physiological activity of recoverin.
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Affiliation(s)
- Sergey E Permyakov
- Institute for Biological Instrumentation of the Russian Academy of Sciences, Federal Research Center Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, 142290 Pushchino, Russia
| | - Alisa S Vologzhannikova
- Institute for Biological Instrumentation of the Russian Academy of Sciences, Federal Research Center Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, 142290 Pushchino, Russia
| | - Ekaterina L Nemashkalova
- Institute for Biological Instrumentation of the Russian Academy of Sciences, Federal Research Center Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, 142290 Pushchino, Russia
| | - Alexei S Kazakov
- Institute for Biological Instrumentation of the Russian Academy of Sciences, Federal Research Center Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, 142290 Pushchino, Russia
- Department of Biomedical Engineering, Pushchino State Institute of Natural Sciences, 142290 Pushchino, Russia
| | - Alexander I Denesyuk
- Institute for Biological Instrumentation of the Russian Academy of Sciences, Federal Research Center Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, 142290 Pushchino, Russia
- Structural Bioinformatics Laboratory, Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, 20520 Turku, Finland
| | - Konstantin Denessiouk
- Structural Bioinformatics Laboratory, Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, 20520 Turku, Finland
- Pharmaceutical Sciences Laboratory, Pharmacy, Faculty of Science and Engineering, Åbo Akademi University, 20520 Turku, Finland
| | - Viktoriia E Baksheeva
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992 Moscow, Russia
| | - Andrey A Zamyatnin
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992 Moscow, Russia
- Institute of Molecular Medicine, Sechenov First Moscow State Medical University, 119991 Moscow, Russia
| | - Evgeni Yu Zernii
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992 Moscow, Russia
- Institute of Molecular Medicine, Sechenov First Moscow State Medical University, 119991 Moscow, Russia
| | - Vladimir N Uversky
- Institute for Biological Instrumentation of the Russian Academy of Sciences, Federal Research Center Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, 142290 Pushchino, Russia.
- Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA.
| | - Eugene A Permyakov
- Institute for Biological Instrumentation of the Russian Academy of Sciences, Federal Research Center Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, 142290 Pushchino, Russia.
- Department of Biomedical Engineering, Pushchino State Institute of Natural Sciences, 142290 Pushchino, Russia.
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6
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Zang J, Neuhauss SCF. The Binding Properties and Physiological Functions of Recoverin. Front Mol Neurosci 2018; 11:473. [PMID: 30618620 PMCID: PMC6306944 DOI: 10.3389/fnmol.2018.00473] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 12/04/2018] [Indexed: 12/14/2022] Open
Abstract
Recoverin (Rcv) is a low molecular-weight, neuronal calcium sensor (NCS) primarily located in photoreceptor outer segments of the vertebrate retina. Calcium ions (Ca2+)-bound Rcv has been proposed to inhibit G-protein-coupled receptor kinase (GRKs) in darkness. During the light response, the Ca2+-free Rcv releases GRK, which in turn phosphorylates visual pigment, ultimately leading to the cessation of the visual transduction cascade. Technological advances over the last decade have contributed significantly to a deeper understanding of Rcv function. These include both biophysical and biochemical approaches that will be discussed in this review article. Furthermore, electrophysiological experiments uncovered additional functions of Rcv, such as regulation of the lifetime of Phosphodiesterase-Transducin complex. Recently, attention has been drawn to different roles in rod and cone photoreceptors.This review article focuses on Rcv binding properties to Ca2+, disc membrane and GRK, and its physiological functions in phototransduction and signal transmission.
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Affiliation(s)
- Jingjing Zang
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
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7
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Brand I, Matyszewska D, Koch KW. Binding of a Myristoylated Protein to the Lipid Membrane Influenced by Interactions with the Polar Head Group Region. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:14022-14032. [PMID: 30360613 DOI: 10.1021/acs.langmuir.8b02265] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Many cytoplasmic proteins contain a hydrophobic acyl chain, which facilitates protein binding to cell membranes. Hydrophobic interactions between the exposed acyl chain of the protein and hydrocarbon chains of lipids in the cell membrane are the driving force for this specific lipid-protein interaction. Recent studies point out that in addition to hydrophobic interactions the charge-charge and charge-dipole interactions between the polar head groups and basic amino acids contribute significantly to the binding process. Recoverin possesses a myristoyl chain at the N-terminus. In the presence of Ca2+ ions, the protein undergoes structural rearrangements, leading to the extrusion of the myristoyl chain, facilitating the protein binding to the membrane. In this work, we investigate the impact of interactions between the polar head group region of lipid molecules and recoverin which binds to the model membrane. The interaction with a planar lipid bilayer composed of phosphatidylcholine and cholesterol with myristoylated and nonmyristoylated recoverin is studied by in situ polarization modulation infrared reflection absorption spectroscopy. The binding of recoverin to the lipid bilayer depends on the transmembrane potential, indicating that the orientation of the permanent surface dipole in the supramolecular assembly of the lipid membrane influences the protein attachment to the membrane surface. Analysis of the amide I' mode indicates that the orientation of recoverin bound to the lipid bilayer is independent of the presence of myristoyl chain in the protein and of the folding of the protein into the tense or relaxed state. In contrast, it changes as a function of the membrane potential. At positive transmembrane potentials, the α-helical fragments of recoverin are oriented predominantly parallel to the bilayer surface. This orientation facilitates the insertion of the acyl chain of the protein into the hydrophobic region of the bilayer. At negative transmembrane potentials, the α-helical fragments of recoverin change their orientation with respect to the membrane surface, which is followed by the removal of the myristoyl chain from the membrane.
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Affiliation(s)
| | - Dorota Matyszewska
- Faculty of Chemistry, Biological and Chemical Research Centre , University of Warsaw , ul. Żwirki i Wigury 101 , 02-089 Warsaw , Poland
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8
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Elbers D, Scholten A, Koch KW. Zebrafish Recoverin Isoforms Display Differences in Calcium Switch Mechanisms. Front Mol Neurosci 2018; 11:355. [PMID: 30323742 PMCID: PMC6172410 DOI: 10.3389/fnmol.2018.00355] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Accepted: 09/11/2018] [Indexed: 12/29/2022] Open
Abstract
Primary steps in vertebrate vision occur in rod and cone cells of the retina and require precise molecular switches in excitation, recovery, and adaptation. In particular, recovery of the photoresponse and light adaptation processes are under control of neuronal Ca2+ sensor (NCS) proteins. Among them, the Ca2+ sensor recoverin undergoes a pronounced Ca2+-dependent conformational change, a prototypical so-called Ca2+-myristoyl switch, which allows selective targeting of G protein-coupled receptor kinase. Zebrafish (Danio rerio) has gained attention as a model organism in vision research. It expresses four different recoverin isoforms (zRec1a, zRec1b, zRec2a, and zRec2b) that are orthologs to the one known mammalian variant. The expression pattern of the four isoforms cover both rod and cone cells, but the differential distribution in cones points to versatile functions of recoverin in these cell types. Initial functional studies on zebrafish larvae indicate different Ca2+-sensitive working modes for zebrafish recoverins, but experimental evidence is lacking so far. The aims of the present study are (1) to measure specific Ca2+-sensing properties of the different recoverin isoforms, (2) to ask whether switch mechanisms triggered by Ca2+ resemble that one observed with mammalian recoverin, and (3) to investigate a possible impact of an attached myristoyl moiety. For addressing these questions, we employ fluorescence spectroscopy, surface plasmon resonance (SPR), dynamic light scattering, and equilibrium centrifugation. Exposure of hydrophobic amino acids, due to the myristoyl switch, differed among isoforms and depended also on the myristoylation state of the particular recoverin. Ca2+-induced rearrangement of the protein-water shell was for all variants less pronounced than for the bovine ortholog indicating either a modified Ca2+-myristoyl switch or no switch. Our results have implications for a step-by-step response of recoverin isoforms to changing intracellular Ca2+ during illumination.
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Affiliation(s)
- Dana Elbers
- Department of Neuroscience, Biochemistry, University of Oldenburg, Oldenburg, Germany
| | - Alexander Scholten
- Department of Neuroscience, Biochemistry, University of Oldenburg, Oldenburg, Germany
| | - Karl-Wilhelm Koch
- Department of Neuroscience, Biochemistry, University of Oldenburg, Oldenburg, Germany
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Vladimirov VI, Zernii EY, Baksheeva VE, Wimberg H, Kazakov AS, Tikhomirova NK, Nemashkalova EL, Mitkevich VA, Zamyatnin AA, Lipkin VM, Philippov PP, Permyakov SE, Senin II, Koch KW, Zinchenko DV. Photoreceptor calcium sensor proteins in detergent-resistant membrane rafts are regulated via binding to caveolin-1. Cell Calcium 2018; 73:55-69. [PMID: 29684785 DOI: 10.1016/j.ceca.2018.04.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 04/07/2018] [Accepted: 04/10/2018] [Indexed: 01/25/2023]
Abstract
Rod cell membranes contain cholesterol-rich detergent-resistant membrane (DRM) rafts, which accumulate visual cascade proteins as well as proteins involved in regulation of phototransduction such as rhodopsin kinase and guanylate cyclases. Caveolin-1 is the major integral component of DRMs, possessing scaffolding and regulatory activities towards various signaling proteins. In this study, photoreceptor Ca2+-binding proteins recoverin, NCS1, GCAP1, and GCAP2, belonging to neuronal calcium sensor (NCS) family, were recognized as novel caveolin-1 interacting partners. All four NCS proteins co-fractionate with caveolin-1 in DRMs, isolated from illuminated bovine rod outer segments. According to pull-down assay, surface plasmon resonance spectroscopy and isothermal titration calorimetry data, they are capable of high-affinity binding to either N-terminal fragment of caveolin-1 (1-101), or its short scaffolding domain (81-101) via a novel structural site. In recoverin this site is localized in C-terminal domain in proximity to the third EF-hand motif and composed of aromatic amino acids conserved among NCS proteins. Remarkably, the binding of NCS proteins to caveolin-1 occurs only in the absence of calcium, which is in agreement with higher accessibility of the caveolin-1 binding site in their Ca2+-free forms. Consistently, the presence of caveolin-1 produces no effect on regulatory activity of Ca2+-saturated recoverin or NCS1 towards rhodopsin kinase, but upregulates GCAP2, which potentiates guanylate cyclase activity being in Ca2+-free conformation. In addition, the interaction with caveolin-1 decreases cooperativity and augments affinity of Ca2 + binding to recoverin apparently by facilitating exposure of its myristoyl group. We suggest that at low calcium NCS proteins are compartmentalized in photoreceptor rafts via binding to caveolin-1, which may enhance their activity or ensure their faster responses on Ca2+-signals thereby maintaining efficient phototransduction recovery and light adaptation.
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Affiliation(s)
- Vasiliy I Vladimirov
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Pushchino, Moscow Region, 142290 Russia
| | - Evgeni Yu Zernii
- Department of Cell Signaling, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992 Russia; Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Moscow 119991, Russia.
| | - Viktoriia E Baksheeva
- Department of Cell Signaling, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992 Russia
| | - Hanna Wimberg
- Department of Neurosciences, Biochemistry Group, University of Oldenburg, Oldenburg, 26111 Germany
| | - Alexey S Kazakov
- Protein Research Group, Institute for Biological Instrumentation 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
| | - Ekaterina L Nemashkalova
- Protein Research Group, Institute for Biological Instrumentation of the Russian Academy of Sciences, Pushchino, Moscow Region, 142290 Russia
| | - Vladimir A Mitkevich
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow 119991, Russia
| | - Andrey A Zamyatnin
- Department of Cell Signaling, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992 Russia; Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Moscow 119991, Russia
| | - Valery M Lipkin
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Pushchino, Moscow Region, 142290 Russia
| | - Pavel P Philippov
- 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
| | - Ivan I Senin
- 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
| | - Dmitry V Zinchenko
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Pushchino, Moscow Region, 142290 Russia
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10
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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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11
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Identification of critical amino acid residues and functional conservation of the Neurospora crassa and Rattus norvegicus orthologues of neuronal calcium sensor-1. Genetica 2016; 144:665-674. [PMID: 27796528 DOI: 10.1007/s10709-016-9933-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 10/11/2016] [Indexed: 10/20/2022]
Abstract
Neuronal calcium sensor-1 (NCS-1) is a member of neuronal calcium sensor family of proteins consisting of an amino terminal myristoylation domain and four conserved calcium (Ca2+) binding EF-hand domains. We performed site-directed mutational analysis of three key amino acid residues that are glycine in the conserved site for the N-terminal myristoylation, a conserved glutamic acid residue responsible for Ca2+ binding in the third EF-hand (EF3), and an unusual non-conserved amino acid arginine at position 175 in the Neurospora crassa NCS-1. The N. crassa strains possessing the ncs-1 mutant allele of these three amino acid residues showed impairment in functions ranging from growth, Ca2+ stress tolerance, and ultraviolet survival. In addition, heterologous expression of the NCS-1 from Rattus norvegicus in N. crassa confirmed its interspecies functional conservation. Moreover, functions of glutamic acid at position 120, the first Ca2+ binding residue among all the EF-hands of the R. norvegicus NCS-1 was found conserved. Thus, we identified three critical amino acid residues of N. crassa NCS-1, and demonstrated its functional conservation across species using the orthologue from R. norvegicus.
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12
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Dell’Orco D, Koch KW. Fingerprints of Calcium-Binding Protein Conformational Dynamics Monitored by Surface Plasmon Resonance. ACS Chem Biol 2016; 11:2390-7. [PMID: 27380526 DOI: 10.1021/acschembio.6b00470] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Surface plasmon resonance (SPR) spectroscopy is widely used to probe interactions involving biological macromolecules by detecting changes in the refractive index in a metal/dielectric interface following the dynamic formation of a molecular complex. In past years, SPR-based experimental approaches were developed to monitor conformational changes induced by the binding of small analytes to proteins coupled to the surface of commercially available sensor chips. A significant contribution to our understanding of the phenomenon came from the study of several Ca(2+)-sensor proteins operating in diverse cellular scenarios, in which the conformational switch is triggered by specific Ca(2+) signals. Structural and physicochemical analyses demonstrated that the SPR signal not only depends on the change in protein size upon Ca(2+)-binding but likely originates from variations in the hydration shell structure. The resulting changes in the dielectric properties of water or of the protein-water interface eventually reflect different crowding conditions on the SPR sensor chip, which mimic the cellular environment. SPR could hence be used to monitor conformational transitions in proteins, especially when a significant variation in the hydrophobicity of the solvent-exposed protein surface occurs, thus leading to changes in the dielectric milieu of the whole sensor chip surface. We review recent work in which SPR has been successfully employed to provide a fingerprint of the conformational change dynamics in proteins under native and altered conditions, which include post-translational modifications, copresence of competing analytes, and point mutations of single amino acids associated with genetic diseases.
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Affiliation(s)
- Daniele Dell’Orco
- Department
of Neurosciences, Biomedicine and Movement Sciences, Section of Biological
Chemistry, University of Verona, I-37134 Verona, Italy
| | - Karl-Wilhelm Koch
- Department
of Neurosciences, Biochemistry Group, University of Oldenburg, D-26111 Oldenburg, Germany
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13
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Potvin-Fournier K, Lefèvre T, Picard-Lafond A, Marcotte C, Dufresne C, Cantin L, Salesse C, Auger M. Discriminating Lipid– from Protein–Calcium Binding To Understand the Interaction between Recoverin and Phosphatidylglycerol Model Membranes. Biochemistry 2016; 55:3481-91. [DOI: 10.1021/acs.biochem.6b00408] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Kim Potvin-Fournier
- Département
de chimie, Regroupement québécois de recherche sur la
fonction, l’ingénierie et les applications des protéines
(PROTEO), Centre de recherche sur les matériaux avancés
(CERMA), Centre québécois sur les matériaux fonctionnels
(CQMF), Université Laval, Pavillon Alexandre-Vachon, 1045
avenue de la médecine, Québec, Québec G1V 0A6, Canada
- CUO-recherche,
Centre de recherche du CHU de Québec, Hôpital du Saint-Sacrement,
Département d’ophtalmologie, Faculté de médecine,
PROTEO, Université Laval, Québec, Québec G1S 4L8, Canada
| | - Thierry Lefèvre
- Département
de chimie, Regroupement québécois de recherche sur la
fonction, l’ingénierie et les applications des protéines
(PROTEO), Centre de recherche sur les matériaux avancés
(CERMA), Centre québécois sur les matériaux fonctionnels
(CQMF), Université Laval, Pavillon Alexandre-Vachon, 1045
avenue de la médecine, Québec, Québec G1V 0A6, Canada
| | - Audrey Picard-Lafond
- Département
de chimie, Regroupement québécois de recherche sur la
fonction, l’ingénierie et les applications des protéines
(PROTEO), Centre de recherche sur les matériaux avancés
(CERMA), Centre québécois sur les matériaux fonctionnels
(CQMF), Université Laval, Pavillon Alexandre-Vachon, 1045
avenue de la médecine, Québec, Québec G1V 0A6, Canada
| | - Catherine Marcotte
- Département
de chimie, Regroupement québécois de recherche sur la
fonction, l’ingénierie et les applications des protéines
(PROTEO), Centre de recherche sur les matériaux avancés
(CERMA), Centre québécois sur les matériaux fonctionnels
(CQMF), Université Laval, Pavillon Alexandre-Vachon, 1045
avenue de la médecine, Québec, Québec G1V 0A6, Canada
| | - Caroline Dufresne
- Département
de chimie, Regroupement québécois de recherche sur la
fonction, l’ingénierie et les applications des protéines
(PROTEO), Centre de recherche sur les matériaux avancés
(CERMA), Centre québécois sur les matériaux fonctionnels
(CQMF), Université Laval, Pavillon Alexandre-Vachon, 1045
avenue de la médecine, Québec, Québec G1V 0A6, Canada
| | - Line Cantin
- CUO-recherche,
Centre de recherche du CHU de Québec, Hôpital du Saint-Sacrement,
Département d’ophtalmologie, Faculté de médecine,
PROTEO, Université Laval, Québec, Québec G1S 4L8, Canada
| | - Christian Salesse
- CUO-recherche,
Centre de recherche du CHU de Québec, Hôpital du Saint-Sacrement,
Département d’ophtalmologie, Faculté de médecine,
PROTEO, Université Laval, Québec, Québec G1S 4L8, Canada
| | - Michèle Auger
- Département
de chimie, Regroupement québécois de recherche sur la
fonction, l’ingénierie et les applications des protéines
(PROTEO), Centre de recherche sur les matériaux avancés
(CERMA), Centre québécois sur les matériaux fonctionnels
(CQMF), Université Laval, Pavillon Alexandre-Vachon, 1045
avenue de la médecine, Québec, Québec G1V 0A6, Canada
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14
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Sulmann S, Wallisch M, Scholten A, Christoffers J, Koch KW. Mapping Calcium-Sensitive Regions in the Neuronal Calcium Sensor GCAP2 by Site-Specific Fluorescence Labeling. Biochemistry 2016; 55:2567-77. [DOI: 10.1021/acs.biochem.6b00005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Stefan Sulmann
- Biochemistry
Group, Department of Neurosciences, Carl von Ossietzky Universität Oldenburg, D-26111 Oldenburg, Germany
| | - Melanie Wallisch
- Institut
für Chemie, Carl von Ossietzky Universität Oldenburg, D-26111 Oldenburg, Germany
| | - Alexander Scholten
- Biochemistry
Group, Department of Neurosciences, Carl von Ossietzky Universität Oldenburg, D-26111 Oldenburg, Germany
| | - Jens Christoffers
- Institut
für Chemie, Carl von Ossietzky Universität Oldenburg, D-26111 Oldenburg, Germany
| | - Karl-Wilhelm Koch
- Biochemistry
Group, Department of Neurosciences, Carl von Ossietzky Universität Oldenburg, D-26111 Oldenburg, Germany
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15
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Lemire S, Jeromin A, Boisselier É. Membrane binding of Neuronal Calcium Sensor-1 (NCS1). Colloids Surf B Biointerfaces 2015; 139:138-47. [PMID: 26705828 DOI: 10.1016/j.colsurfb.2015.11.065] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 10/29/2015] [Accepted: 11/22/2015] [Indexed: 01/10/2023]
Abstract
Neuronal Calcium Sensor-1 (NCS1) belongs to the family of Neuronal Calcium Sensor (NCS) proteins. NCS1 is composed of four EF-hand motifs and an N-terminal myristoylation. However, the presence of a calcium-myristoyl switch in NCS1 and its role in the membrane binding are controversial. The model of Langmuir lipid monolayers is thus used to mimic the cell membrane in order to characterize the membrane interactions of NCS1. Two binding parameters are calculated from monolayer measurements: the maximum insertion pressure, up to which protein binding is energetically favorable, and the synergy, reporting attractive or repulsive interactions with the lipid monolayers. Binding membrane measurements performed in the presence of myristoylated NCS1 reveal better binding interactions for phospholipids composed of phosphoethanolamine polar head groups and unsaturated fatty acyl chains. In the absence of calcium, the membrane binding measurements are drastically modified and suggest that the protein is more strongly bound to the membrane. Indeed, the binding of calcium by three EF-hand motifs of NCS1 leads to a conformation change. NCS1 arrangement at the membrane could thus be reshuffled for better interactions with its substrates. The N-terminal peptide of NCS1 is composed of two amphiphilic helices involved in the membrane interactions of NCS1. Moreover, the presence of the myristoyl group has a weak influence on the membrane binding of NCS1 suggesting the absence of a calcium-myristoyl switch mechanism in this protein. The myristoylation could thus have a structural role required in the folding/unfolding of NCS1 which is essential to its multiple biological functions.
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Affiliation(s)
- Samuel Lemire
- CUO-Recherche, Hôpital du Saint-Sacrement, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de médecine, Université Laval, Québec, Québec, Canada
| | | | - Élodie Boisselier
- CUO-Recherche, Hôpital du Saint-Sacrement, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de médecine, Université Laval, Québec, Québec, Canada.
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16
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Kumar RP, Ranaghan MJ, Ganjei AY, Oprian DD. Crystal Structure of Recoverin with Calcium Ions Bound to Both Functional EF Hands. Biochemistry 2015; 54:7222-8. [PMID: 26584024 DOI: 10.1021/acs.biochem.5b01160] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Recoverin (Rv), a small Ca(2+)-binding protein that inhibits rhodopsin kinase (RK), has four EF hands, two of which are functional (EF2 and EF3). Activation requires Ca(2+) in both EF hands, but crystal structures have never been observed with Ca(2+) ions in both sites; all previous structures have Ca(2+) bound to only EF3. We suspected that this was due to an intermolecular crystal contact between T80 and a surface glutamate (E153) that precluded coordination of a Ca(2+) ion in EF2. We constructed the E153A mutant, determined its X-ray crystal structure to 1.2 Å resolution, and showed that two Ca(2+) ions are bound, one in EF3 and one in EF2. Additionally, several other residues are shown to adopt conformations in the 2Ca(2+) structure not seen previously and not seen in a second structure of the E153A mutant containing Na(+) instead of Ca(2+) in the EF2 site. The side-chain rearrangements in these residues form a 28 Å allosteric cascade along the surface of the protein connecting the Ca(2+)-binding site of EF2 with the active-site pocket responsible for binding RK.
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Affiliation(s)
- Ramasamy P Kumar
- Department of Biochemistry, Brandeis University , Waltham, Massachusetts 02454, United States
| | - Matthew J Ranaghan
- Department of Biochemistry, Brandeis University , Waltham, Massachusetts 02454, United States
| | - Allen Y Ganjei
- Department of Biochemistry, Brandeis University , Waltham, Massachusetts 02454, United States
| | - Daniel D Oprian
- Department of Biochemistry, Brandeis University , Waltham, Massachusetts 02454, United States
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17
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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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18
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Sulmann S, Vocke F, Scholten A, Koch KW. Retina specific GCAPs in zebrafish acquire functional selectivity in Ca2+-sensing by myristoylation and Mg2+-binding. Sci Rep 2015; 5:11228. [PMID: 26061947 PMCID: PMC4462140 DOI: 10.1038/srep11228] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 05/18/2015] [Indexed: 11/09/2022] Open
Abstract
Zebrafish photoreceptor cells express six guanylate cyclase-activating proteins (zGCAPs) that share a high degree of amino acid sequence homology, but differ in Ca(2+)-binding properties, Ca(2+)-sensitive target regulation and spatial-temporal expression profiles. We here study a general problem in cellular Ca(2+)-sensing, namely how similar Ca(2+)-binding proteins achieve functional selectivity to control finely adjusted cellular responses. We investigated two parameters of critical importance for the trigger and switch function of guanylate cyclase-activating proteins: the myristoylation status and the occupation of Ca(2+)-binding sites with Mg(2+). All zGCAPs can be myristoylated in living cells using click chemistry. Myristoylation does not facilitate membrane binding of zGCAPs, but it significantly modified the regulatory properties of zGCAP2 and zGCAP5. We further determined for all zGCAPs at least two binding sites exhibiting high affinities for Ca(2+) with KD values in the submicromolar range, whereas for other zGCAPs (except zGCAP3) the affinity of the third binding site was in the micromolar range. Mg(2+) either occupied the low affinity Ca(2+)-binding site or it shifted the affinities for Ca(2+)-binding. Hydrodynamic properties of zGCAPs are more influenced by Ca(2+) than by Mg(2+), although to a different extent for each zGCAP. Posttranslational modification and competing ion-binding can tailor the properties of similar Ca(2+)-sensors.
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Affiliation(s)
- Stefan Sulmann
- Department of Neurosciences, Biochemistry Group, University of Oldenburg, D-26111-Oldenburg, Germany
| | - Farina Vocke
- Department of Neurosciences, Biochemistry Group, University of Oldenburg, D-26111-Oldenburg, Germany
| | - Alexander Scholten
- Department of Neurosciences, Biochemistry Group, University of Oldenburg, D-26111-Oldenburg, Germany
| | - Karl-Wilhelm Koch
- Department of Neurosciences, Biochemistry Group, University of Oldenburg, D-26111-Oldenburg, Germany
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19
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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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20
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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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21
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Marino V, Sulmann S, Koch KW, Dell'Orco D. Structural effects of Mg²⁺ on the regulatory states of three neuronal calcium sensors operating in vertebrate phototransduction. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1853:2055-65. [PMID: 25447547 DOI: 10.1016/j.bbamcr.2014.10.026] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 10/25/2014] [Accepted: 10/28/2014] [Indexed: 12/13/2022]
Abstract
The effects of physiological concentration of magnesium on the switch states of the neuronal calcium sensor proteins recoverin, GCAP1 and GCAP2 were investigated. Isothermal titration calorimetry was applied for binding studies. Circular dichroism spectroscopy was used to characterize protein thermal stability, secondary and tertiary structure in conditions of high and low [Ca²⁺], mimicking respectively the dark-adapted and light-exposed photoreceptor states during the phototransduction cascade. Further, molecular dynamics (MD) simulations were run to investigate the dynamical structural properties of GCAP1 in its activator, inhibitor and putative transitory states. Our results confirmed that Mg²⁺ is unable to trigger the typical Ca²⁺-induced conformational change of recoverin (myristoyl switch) while it decreases its thermal stability. Interestingly, Mg²⁺ seems to affect the conformation of GCAP2 both at high and low [Ca²⁺], however the variations are more substantial for myristoylated GCAP2 in the absence of Ca²⁺. GCAP1 is responsive to Mg²⁺ only in its low [Ca²⁺] state and Mg²⁺-GCAP1 tertiary structure slightly differs from both apo and Ca²⁺-bound states. Finally, MD simulations suggest that the GCAP1 state harboring one Mg²⁺ ion bound to EF2 acquires structural characteristics that are thought to be relevant for the activation of the guanylate cyclase. Moreover, all the putative Mg²⁺-bound states of myristoylated GCAP1 are structurally less flexible than Ca²⁺-bound states. GCAP1 acquires a more compact tertiary structure that is less accessible to the solvent, thereby inducing a different conformation to the myristoyl moiety, which might be crucial for the activation of the guanylate cyclase. This article is part of a Special Issue entitled: 13th European Symposium on Calcium.
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Affiliation(s)
- Valerio Marino
- Department of Life Sciences and Reproduction, Section of Biological Chemistry, University of Verona, Italy
| | - Stefan Sulmann
- Department of Neurosciences, Biochemistry Group, University of Oldenburg, Germany
| | - Karl-Wilhelm Koch
- Department of Neurosciences, Biochemistry Group, University of Oldenburg, Germany
| | - Daniele Dell'Orco
- Department of Life Sciences and Reproduction, Section of Biological Chemistry, University of Verona, Italy; Center for BioMedical Computing (CBMC), University of Verona, Italy.
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22
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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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23
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Marino V, Astegno A, Pedroni M, Piccinelli F, Dell'Orco D. Nanodevice-induced conformational and functional changes in a prototypical calcium sensor protein. NANOSCALE 2014; 6:412-423. [PMID: 24213152 DOI: 10.1039/c3nr04978g] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Calcium (Ca(2+)) plays a major role in a variety of cellular processes. Fine changes in its concentration are detected by calcium sensor proteins, which adopt specific conformations to regulate their molecular targets. Here, two distinct nanodevices were probed as biocompatible carriers of Ca(2+)-sensors and the structural and functional effects of protein-nanodevice interactions were investigated. The prototypical Ca(2+)-sensor recoverin (Rec) was incubated with 20-25 nm CaF2 nanoparticles (NPs) and 70-80 nm liposomes with lipid composition similar to that found in photoreceptor cells. Circular dichroism and fluorescence spectroscopy were used to characterize changes in the protein secondary and tertiary structure and in thermal stability upon interaction with the nanodevice, both in the presence and in the absence of free Ca(2+). Variations in the hydrodynamic diameter of the complex were measured by dynamic light scattering and the residual capability of the protein to act as a Ca(2+)-sensor in the presence of NPs was estimated spectroscopically. The conformation, thermal stability and Ca(2+)-sensing capability of Rec were all significantly affected by the presence of NPs, while liposomes did not significantly perturb Rec conformation and function, allowing reversible binding. NP-bound Rec maintained an all-helical fold but showed lower thermal stability and high cooperativity of unfolding. Our analysis can be proficiently used to validate the biocompatibility of other nanodevices intended for biomedical applications involving Ca(2+)-sensors.
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Affiliation(s)
- Valerio Marino
- Department of Life Sciences and Reproduction, Section of Biological Chemistry, University of Verona, Verona, Italy.
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Potvin-Fournier K, Lefèvre T, Picard-Lafond A, Valois-Paillard G, Cantin L, Salesse C, Auger M. The thermal stability of recoverin depends on calcium binding and its myristoyl moiety as revealed by infrared spectroscopy. Biochemistry 2013; 53:48-56. [PMID: 24359287 DOI: 10.1021/bi401336g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
To evaluate the structural stability of recoverin, a member of the neuronal calcium sensor family, the effect of temperature, myristoylation, and calcium:protein molar ratio on its secondary structure has been studied by transmission infrared spectroscopy. On the basis of the data, the protein predominantly adopts α-helical structures (∼50-55%) with turns, unordered structures, and β-sheets at 25 °C. The data show no significant impact of the presence of calcium and myristoylation on secondary structure. It is found that, in the absence of calcium, recoverin denatures and self-aggregates while being heated, with the formation of intermolecular antiparallel β-sheets. The nonmyristoylated protein (Rec-nMyr) exhibits a lower temperature threshold of aggregation and a higher intermolecular β-sheet content at 65 °C than the myristoylated protein (Rec-Myr). The former thus appears to be less thermally stable than the latter. In the presence of excess calcium ions (calcium:protein ratio of 10), the protein is thermally stable up to 65 °C with no significant conformational change, the presence of the myristoyl chain having no effect on the thermal stability of recoverin under these conditions. A decrease in the thermal stability of recoverin is observed as the calcium:protein molar ratio decreases, with Rec-nMyr being less stable than Rec-Myr. The data overall suggest that a minimal number of coordinated calcium ions is necessary to fully stabilize the structure of recoverin and that, when bound to the membrane, i.e., when the myristoyl chain protrudes from the interior pocket, recoverin should be more stable than in a Ca-free solution, i.e., when the myristoyl chain is sequestered in the interior.
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Affiliation(s)
- Kim Potvin-Fournier
- Département de chimie, Regroupement québécois de recherche sur la fonction, la structure et l'ingénierie des protéines (PROTEO), Centre de recherche sur les matériaux avancés (CERMA), Université Laval , Pavillon Alexandre-Vachon, 1045 avenue de la médecine, Québec, Québec G1V 0A6, Canada
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Ranaghan MJ, Kumar RP, Chakrabarti KS, Buosi V, Kern D, Oprian DD. A highly conserved cysteine of neuronal calcium-sensing proteins controls cooperative binding of Ca2+ to recoverin. J Biol Chem 2013; 288:36160-7. [PMID: 24189072 DOI: 10.1074/jbc.m113.524355] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Recoverin, a 23-kDa Ca(2+)-binding protein of the neuronal calcium sensing (NCS) family, inhibits rhodopsin kinase, a Ser/Thr kinase responsible for termination of photoactivated rhodopsin in rod photoreceptor cells. Recoverin has two functional EF hands and a myristoylated N terminus. The myristoyl chain imparts cooperativity to the Ca(2+)-binding sites through an allosteric mechanism involving a conformational equilibrium between R and T states of the protein. Ca(2+) binds preferentially to the R state; the myristoyl chain binds preferentially to the T state. In the absence of myristoylation, the R state predominates, and consequently, binding of Ca(2+) to the non-myristoylated protein is not cooperative. We show here that a mutation, C39A, of a highly conserved Cys residue among NCS proteins, increases the apparent cooperativity for binding of Ca(2+) to non-myristoylated recoverin. The binding data can be explained by an effect on the T/R equilibrium to favor the T state without affecting the intrinsic binding constants for the two Ca(2+) sites.
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Wache N, Scholten A, Klüner T, Koch KW, Christoffers J. Turning On Fluorescence with Thiols - Synthetic and Computational Studies on Diaminoterephthalates and Monitoring the Switch of the Ca2+Sensor Recoverin. European J Org Chem 2012. [DOI: 10.1002/ejoc.201200879] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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Fries R, Scholten A, Säftel W, Koch KW. Operation profile of zebrafish guanylate cyclase-activating protein 3. J Neurochem 2012; 121:54-65. [PMID: 22212098 DOI: 10.1111/j.1471-4159.2011.07643.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The expression pattern and property profile of the neuronal Ca(2+) sensor guanylate cyclase-activating protein 3 (zGCAP3) was studied by immunochemical approaches, biophysical methods and enzymatic assays. Using affinity purified antibodies immunoreactivity towards zGCAP3 was weakly detected in the outer and strongly in the inner segments of cone cells as well as in the outer plexiform layer, to a lesser degree also in the inner plexiform and ganglion cell layer of the zebrafish retina. This cellular distribution was independent of a dark/light cycle. Some neuronal Ca(2+) sensors are acylated (mainly myristoylated) at the amino-terminus. Probing larval and adult stages of the developing zebrafish retina indicated that zGCAP3 was first expressed in a non-myristoylated form, but was finally present in the adult retina as a myristoylated protein. While zGCAP3 did not undergo a classical Ca(2+) -myristoyl switch as investigated by surface plasmon resonance spectroscopy, myristoylation had two main other consequences: it enhanced the Ca(2+) -sensitivity of the Ca(2+) -induced conformational change and it stabilized the protein conformation. Differences between myristoylated and non-myristoylated zGCAP3 were also observed in modulating the kinetic and catalytic parameters of the GCAP-target, a membrane bound guanylate cyclase. Thus, the stabilizing effect of the myristoyl group is apparently less important in the larval than in the adult fish.
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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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Wache N, Schröder C, Koch KW, Christoffers J. Diaminoterephthalate Turn-On Fluorescence Probes for Thiols-Tagging of Recoverin and Tracking of its Conformational Change. Chembiochem 2012; 13:993-8. [DOI: 10.1002/cbic.201200027] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Indexed: 11/08/2022]
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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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Dell'Orco D, Sulmann S, Linse S, Koch KW. Dynamics of conformational Ca2+-switches in signaling networks detected by a planar plasmonic device. Anal Chem 2012; 84:2982-9. [PMID: 22404528 DOI: 10.1021/ac300213j] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Ca(2+)-sensor proteins regulate a variety of intracellular processes by adopting specific conformations in response to finely tuned changes in Ca(2+)-concentration. Here we present a surface plasmon resonance (SPR)-based approach, which allows for simultaneous detection of conformational dynamics of four Ca(2+)-sensor proteins (calmodulin, recoverin, GCAP1, and GCAP2) operating in the vertebrate phototransduction cascade, over variations in Ca(2+) concentration in the 0.1-0.6 μM range. By working at conditions that quantitatively mimic those found in the cell, we show that the method is able to detect subtle differences in the dynamics of each Ca(2+)-sensor, which appear to be influenced by the presence of free Mg(2+) at physiological concentration and by posttranslational modifications such as myristoylation. Comparison between the macroscopic Ca(2+)-binding constants, directly measured by competition with a chromophoric chelator, and the concerted binding-conformational switch detected by SPR at equilibrium reveals the relative contribution of the conformational change process to the SPR signal. This process appears to be influenced by the presence of other cations that perturb Ca(2+)-binding and the conformational transition by competing with Ca(2+), or by pure electrostatic screening. In conclusion, the approach described here allows a comparative analysis of protein conformational changes occurring under physiologically relevant molecular crowding conditions in ultrathin biosensor layers.
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Affiliation(s)
- Daniele Dell'Orco
- Institute of Biology and Environmental Sciences, University of Oldenburg, Oldenburg, Germany.
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A dynamic scaffolding mechanism for rhodopsin and transducin interaction in vertebrate vision. Biochem J 2012; 440:263-71. [PMID: 21843151 DOI: 10.1042/bj20110871] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The early steps in vertebrate vision require fast interactions between Rh (rhodopsin) and Gt (transducin), which are classically described by a collisional coupling mechanism driven by the free diffusion of monomeric proteins on the disc membranes of rod and cone cells. Recent findings, however, point to a very low mobility for Rh and support a substantially different supramolecular organization. Moreover, Rh-G(t) interactions seem to possibly occur even prior to light stimuli, which is also difficult to reconcile with the classical scenario. We investigated the kinetics of interaction between native Rh and G(t) in different conditions by surface plasmon resonance and analysed the results in the general physiological context by employing a holistic systems modelling approach. The results from the present study point to a mechanism that is intermediate between pure collisional coupling and physical scaffolding. Such a 'dynamic scaffolding', in which prevalently dimeric Rh and G(t) interact in the dark by forming transient complexes (~25% of G(t) is precoupled to Rh), does not slow down the phototransduction cascade, but is compatible with the observed photoresponses on a broad scale of light stimuli. We conclude that Rh molecules and Rh-G(t) complexes can both absorb photons and trigger the visual cascade.
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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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Senin II, Tikhomirova NK, Churumova VA, Grigoriev II, Kolpakova TA, Zinchenko DV, Philippov PP, Zernii EY. Amino acid sequences of two immune-dominant epitopes of recoverin are involved in Ca2+/recoverin-dependent inhibition of phosphorylation of rhodopsin. BIOCHEMISTRY (MOSCOW) 2011; 76:332-8. [PMID: 21568868 DOI: 10.1134/s0006297911030060] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Antibodies AB(60-72) and AB(80-92) against two immune-dominant epitopes of photoreceptor Ca(2+)-binding protein recoverin, 60-DPKAYAQHVFRSF-72 and 80-LDFKEYVIALHMT-92, which can be exposed in a Ca(2+)-dependent manner, were obtained. The presence of AB(60-72) or AB(80-92) results in a slight increase in Ca(2+)-affinity of recoverin and does not affect significantly a Ca(2+)-myristoyl switch mechanism of the protein. However in the presence of AB(60-72) or AB(80-92) recoverin loses its ability to interact with rhodopsin kinase and consequently to perform a function of Ca(2+)-sensitive inhibitor of rhodopsin phosphorylation in photoreceptor cells.
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Affiliation(s)
- I I Senin
- Department of Cell Signaling, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Russia.
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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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Nullmeier M, Koliwer-Brandl H, Kelm S, Zägel P, Koch KW, Brand I. Impact of Strong and Weak Lipid-Protein Interactions on the Structure of a Lipid Bilayer on a Gold Electrode Surface. Chemphyschem 2011; 12:1066-79. [DOI: 10.1002/cphc.201100036] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Revised: 02/07/2011] [Indexed: 01/13/2023]
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Permyakov SE, Zernii EY, Knyazeva EL, Denesyuk AI, Nazipova AA, Kolpakova TV, Zinchenko DV, Philippov PP, Permyakov EA, Senin II. Oxidation mimicking substitution of conservative cysteine in recoverin suppresses its membrane association. Amino Acids 2011; 42:1435-42. [PMID: 21344177 DOI: 10.1007/s00726-011-0843-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Accepted: 02/03/2011] [Indexed: 11/26/2022]
Abstract
Recoverin belongs to the family of intracellular Ca(2+)-binding proteins containing EF-hand domains, neuronal calcium sensors (NCS). In photoreceptor outer segments, recoverin is involved into the recovery of visual cycle via Ca(2+)-dependent interaction with disk membranes and inhibition of rhodopsin kinase. The function of a conservative within NCS family Cys residue in the inactive EF-loop 1 remains unclear, but previous study has shown its vulnerability to oxidation under mild oxidizing conditions. To elucidate the influence of oxidation of the conservative Cys39 in recoverin the properties of its C39D mutant, mimicking oxidative conversion of Cys39 into sulfenic, sulfinic or sulfonic acids have been studied using intrinsic fluorescence, circular dichroism, and equilibrium centrifugation methods. The C39D substitution results in essential changes in structural, physico-chemical and physiological properties of the protein: it reduces α-helical content, decreases thermal stability and suppresses protein affinity for photoreceptor membranes. The latter effect precludes proper functioning of the Ca(2+)-myristoyl switch in recoverin. The revealed significance of oxidation state of Cys39 for maintaining the protein functional status shows that it may serve as redox sensor in vision and suggests an explanation of the available data on localization and light-dependent translocation of recoverin in rod photoreceptors.
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Affiliation(s)
- Sergei E Permyakov
- Institute for Biological Instrumentation of Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
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Dell'Orco D, Müller M, Koch KW. Quantitative detection of conformational transitions in a calcium sensor protein by surface plasmon resonance. Chem Commun (Camb) 2010; 46:7316-8. [PMID: 20835460 DOI: 10.1039/c0cc02086a] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We determined the conditions under which surface plasmon resonance can be used to monitor at real-time the Ca(2+)-induced conformational transitions of the sensor protein recoverin immobilized over a sensor chip. The equilibrium and the kinetics of conformational transitions were detected and quantified over a physiological range of Ca(2+) and protein concentrations similar to those found within cells. Structural analysis suggests that the detection principle reflects changes in the hydrodynamic properties of the protein and is not due to a mass effect. The phenomenon appears to be related to changes in the refractive index at the metal/dielectric interface.
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Affiliation(s)
- Daniele Dell'Orco
- Institute of Biology and Environmental Sciences, Biochemistry Group, University of Oldenburg, D-26111 Oldenburg, Germany.
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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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Komolov KE, Senin II, Kovaleva NA, Christoph MP, Churumova VA, Grigoriev II, Akhtar M, Philippov PP, Koch KW. Mechanism of rhodopsin kinase regulation by recoverin. J Neurochem 2009; 110:72-9. [PMID: 19457073 DOI: 10.1111/j.1471-4159.2009.06118.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Recoverin is suggested to inhibit rhodopsin kinase (GRK1) at high [Ca(2+)] in the dark state of the photoreceptor cell. Decreasing [Ca(2+)] terminates inhibition and facilitates phosphorylation of illuminated rhodopsin (Rh*). When recoverin formed a complex with GRK1, it did not interfere with the phosphorylation of a C-terminal peptide of rhodopsin (S338-A348) by GRK1. Furthermore, while GRK1 competed with transducin on interaction with rhodopsin and thereby suppressed GTPase activity of transducin, recoverin in the complex with GRK1 did not influence this competition. Constructs of GRK1 that encompass its N-terminal, catalytic or C-terminal domains were used in pull-down assays and surface plasmon resonance analysis to monitor interaction. Ca(2+)-recoverin bound to the N-terminus of GRK1, but did not bind to the other constructs. GRK1 interacted with rhodopsin also by its N-terminus in a light-dependent manner. No interaction was observed with the C-terminus. We conclude that inhibition of GRK1 by recoverin is not the result of their direct competition for the same docking site on Rh*, although the interaction sites of GRK1/Rh* and GRK1/recoverin partially overlap. The N-terminus of GRK1 is recognized by Rh* leading to a conformational change which moves the C-terminus of Rh* into the catalytic kinase groove. Ca(2+)-recoverin interacting with the N-terminus of GRK1 prevents this conformational change and thus blocks Rh* phosphorylation by GRK1.
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Senin II, Churumova VA, Philippov PP, Koch KW. Membrane binding of the neuronal calcium sensor recoverin - modulatory role of the charged carboxy-terminus. BMC BIOCHEMISTRY 2007; 8:24. [PMID: 18034895 PMCID: PMC2203989 DOI: 10.1186/1471-2091-8-24] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2007] [Accepted: 11/22/2007] [Indexed: 11/10/2022]
Abstract
BACKGROUND The Ca2+-binding protein recoverin operates as a Ca2+-sensor in vertebrate photoreceptor cells. It undergoes a so-called Ca2+-myristoyl switch when cytoplasmic Ca2+-concentrations fluctuate in the cell. Its covalently attached myristoyl-group is exposed at high Ca2+-concentrations and enables recoverin to associate with lipid bilayers and to inhibit its target rhodopsin kinase. At low Ca2+-concentrations the myristoyl group is inserted into a hydrophobic pocket of recoverin thereby relieving inhibitory constraint on rhodopsin kinase. Hydrophobic and electrostatic interactions of recoverin with membranes have not been clearly determined, in particular the function of the positively charged carboxy-terminus in recoverin 191QKVKEKLKEKKL202 in this context is poorly understood. RESULTS Binding of myristoylated recoverin to lipid bilayer depends on the charge distribution in phospholipids. Binding was tested by equilibrium centrifugation and surface plasmon resonance (SPR) assays. It is enhanced to a certain degree by the inclusion of phosphatidylserine (up to 60%) in the lipid mixture. However, a recoverin mutant that lacked the charged carboxy-terminus displayed the same relative binding amplitudes as wildtype (WT) recoverin when bound to neutral or acidic lipids. Instead, the charged carboxy-terminus of recoverin has a significant impact on the biphasic dissociation of recoverin from membranes. On the other hand, the nonmyristoylated WT and truncated mutant form of recoverin did not bind to lipid bilayers to a substantial amount as binding amplitudes observed in SPR measurements are similar to bulk refractive index changes. CONCLUSION Our data indicate a small, but evident electrostatic contribution to the overall binding energy of recoverin association with lipid bilayer. Properties of the charged carboxy-terminus are consistent with a role of this region as an internal effector region that prolongs the time recoverin stays on the membrane by influencing its Ca2+-sensitivity.
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Affiliation(s)
- Ivan I Senin
- Department of Biology and Environmental Sciences (Biochemistry group), University of Oldenburg, D-26111 Oldenburg, Germany.
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Permyakov SE, Nazipova AA, Denesyuk AI, Bakunts AG, Zinchenko DV, Lipkin VM, Uversky VN, Permyakov EA. Recoverin as a redox-sensitive protein. J Proteome Res 2007; 6:1855-63. [PMID: 17385906 DOI: 10.1021/pr070015x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Recoverin is a member of the neuronal calcium sensor (NCS) family of EF-hand calcium binding proteins. In a visual cycle of photoreceptor cells, recoverin regulates activity of rhodopsin kinase in a Ca2+-dependent manner. Like all members of the NSC family, recoverin contains a conserved cysteine (Cys38) in nonfunctional EF-hand 1. This residue was shown to be critical for activation of target proteins in some members of the NCS family but not for interaction of recoverin with rhodopsin kinase. Spectrophotometric titration of Ca2+-loaded recoverin gave 7.6 for the pKa value of Cys38 thiol, suggesting partial deprotonation of the thiol in vivo conditions. An ability of recoverin to form a disulfide dimer and thiol-oxidized monomer under mild oxidizing conditions was found using SDS-PAGE in reducing and nonreducing conditions and Ellman's test. Both processes are reversible and modulated by Ca2+. Although formation of the disulfide dimer takes place only for Ca2+-loaded recoverin, accumulation of the oxidized monomer proceeds more effectively for apo-recoverin. The Ca2+ modulated susceptibility of the recoverin thiol to reversible oxidation may be of potential importance for functioning of recoverin in photoreceptor cells.
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Affiliation(s)
- Sergei E Permyakov
- Institute for Biological Instrumentation of the Russian Academy of Sciences, Pushchino, Moscow Region 142290, Russia
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Gensch T, Komolov KE, Senin II, Philippov PP, Koch KW. Ca2+-dependent conformational changes in the neuronal Ca2+-sensor recoverin probed by the fluorescent dye Alexa647. Proteins 2007; 66:492-9. [PMID: 17078090 DOI: 10.1002/prot.21231] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Recoverin belongs to the superfamily of EF-hand Ca2+-binding proteins and operates as a Ca2+-sensor in vertebrate photoreceptor cells, where it regulates the activity of rhodopsin kinase GRK1 in a Ca2+-dependent manner. Ca2+-dependent conformational changes in recoverin are allosterically controlled by the covalently attached myristoyl group. The amino acid sequence of recoverin harbors a unique cysteine at position 38. The cysteine can be modified by the fluorescent dye Alexa647 using a maleimide-thiol coupling step. Introduction of Alexa647 into recoverin did not disturb the biological function of recoverin, as it can regulate rhodopsin kinase activity like unlabeled recoverin. Performance of the Ca2+-myristoyl switch of labeled recoverin was monitored by Ca2+-dependent association with immobilized lipids using surface plasmon resonance spectroscopy. When the Ca2+-concentration was varied, labeled myristoylated recoverin showed a 37%-change in fluorescence emission and a 34%-change in excitation intensity, emission and excitation maxima shifted by 6 and 18 nm, respectively. In contrast, labeled nonmyristoylated recoverin exhibited only minimal changes. Time-resolved fluorescence measurements showed biexponentiell fluorescence decay, in which the slower time constant of 2 ns was specifically influenced by Ca2+-induced conformational changes. A similar influence on the slower time constant was observed with the recoverin mutant RecE85Q that has a disabled EF-hand 2, but no such influence was detected with the mutant RecE121Q (EF-hand 3 is nonfunctional) that contains the myristoyl group in a clamped position. We conclude from our results that Alexa647 bound to cysteine 38 can monitor the conformational transition in recoverin that is under control of the myristoyl group.
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Affiliation(s)
- Thomas Gensch
- IBI-1, Forschungszentrum Jülich, Jülich D-52425, Germany
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Burgoyne RD. Neuronal calcium sensor proteins: generating diversity in neuronal Ca2+ signalling. Nat Rev Neurosci 2007; 8:182-93. [PMID: 17311005 PMCID: PMC1887812 DOI: 10.1038/nrn2093] [Citation(s) in RCA: 426] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In neurons, intracellular calcium signals have crucial roles in activating neurotransmitter release and in triggering alterations in neuronal function. Calmodulin has been widely studied as a Ca(2+) sensor that has several defined roles in neuronal Ca(2+) signalling, but members of the neuronal calcium sensor protein family have also begun to emerge as key components in a number of regulatory pathways and have increased the diversity of neuronal Ca(2+) signalling pathways. The differing properties of these proteins allow them to have discrete, non-redundant functions.
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Affiliation(s)
- Robert D Burgoyne
- The Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, UK.
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Weiergräber OH, Senin II, Zernii EY, Churumova VA, Kovaleva NA, Nazipova AA, Permyakov SE, Permyakov EA, Philippov PP, Granzin J, Koch KW. Tuning of a neuronal calcium sensor. J Biol Chem 2006; 281:37594-602. [PMID: 17015448 DOI: 10.1074/jbc.m603700200] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Recoverin is a Ca(2+)-regulated signal transduction modulator expressed in the vertebrate retina that has been implicated in visual adaptation. An intriguing feature of recoverin is a cluster of charged residues at its C terminus, the functional significance of which is largely unclear. To elucidate the impact of this segment on recoverin structure and function, we have investigated a mutant lacking the C-terminal 12 amino acids. Whereas in myristoylated recoverin the truncation causes an overall decrease in Ca(2+) sensitivity, results for the non-myristoylated mutant indicate that the truncation primarily affects the high affinity EF-hand 3. The three-dimensional structure of the mutant has been determined by x-ray crystallography. In addition to significant changes in average coordinates compared with wild-type recoverin, the structure provides strong indication of increased conformational flexibility, particularly in the C-terminal domain. Based on these observations, we propose a novel role of the C-terminal segment of recoverin as an internal modulator of Ca(2+) sensitivity.
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Affiliation(s)
- Oliver H Weiergräber
- Institut für Biologische Informationsverarbeitung (IBI-2, Biologische Strukturforschung), Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany
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46
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Senin II, Bosch L, Ramon E, Zernii EY, Manyosa J, Philippov PP, Garriga P. Ca2+/recoverin dependent regulation of phosphorylation of the rhodopsin mutant R135L associated with retinitis pigmentosa. Biochem Biophys Res Commun 2006; 349:345-52. [PMID: 16934219 DOI: 10.1016/j.bbrc.2006.08.048] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2006] [Accepted: 08/11/2006] [Indexed: 11/19/2022]
Abstract
No single molecular mechanism accounts for the effect of mutations in rhodopsin associated with retinitis pigmentosa. Here we report on the specific effect of a Ca2+/recoverin upon phosphorylation of the autosomal dominant retinitis pigmentosa R135L rhodopsin mutant. This mutant shows specific features like impaired G-protein signaling but enhanced phosphorylation in the shut-off process. We now report that R135L hyperphosphorylation by rhodopsin kinase is less efficiently inhibited by Ca2+/recoverin than wild-type rhodopsin. This suggests an involvement of Ca2+/recoverin into the molecular pathogenic effect of the mutation in retinitis pigmentosa which is the cause of rod photoreceptor cell degeneration. This new proposed role of Ca2+/recoverin may be one of the specific features of the proposed new Type III class or rhodopsin mutations associated with retinitis pigmentosa.
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Affiliation(s)
- Ivan I Senin
- Department of Cell Signalling, A. N. Belozersky Institute of Physico-Chemical Biology, M.V. Lomonosov Moscow State University, Russia
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N/A, 夏 时. N/A. Shijie Huaren Xiaohua Zazhi 2006; 14:1602-1607. [DOI: 10.11569/wcjd.v14.i16.1602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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Korovkina VP, Brainard AM, England SK. Translocation of an endoproteolytically cleaved maxi-K channel isoform: mechanisms to induce human myometrial cell repolarization. J Physiol 2006; 573:329-41. [PMID: 16527852 PMCID: PMC1779727 DOI: 10.1113/jphysiol.2006.106922] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Large conductance Ca(2+)- and voltage-activated K+ (maxi-K) channels modulate human myometrial smooth muscle cell (hMSMC) excitability; however, the role of individual alternatively spliced isoforms remains unclear. We have previously shown that the transcript of a human maxi-K channel isoform (mK44) is expressed predominantly in myometrial and aortic smooth muscle and forms a functional channel in heterologous expression systems. The mK44 isoform contains unique consensus motifs for both endoproteolytic cleavage and N-myristoylation, although the function of these post-translational modifications is unknown. The goal of these studies was to determine the role of post-translational modifications in regulating mK44 channel function in hMSMCs. An mK44-specific antibody indicated that this channel is localized intracellularly in hMSMCs and translocates to the cell membrane in response to increases in intracellular Ca(2+). Immunological analyses using an N-terminally myc-tagged mK44 construct demonstrated endoproteolytical cleavage of mK44 in hMSMCs resulting in membrane localization of the mK44 N-termini and intracellular retention of the pore-forming C-termini. Caffeine-induced Ca(2+) release from intracellular stores resulted in translocation of the C-termini of mK44 to the cell membrane and co-localization with its N-termini. Translocation of mK44 channels to the cell membrane was concomitant with repolarization of the hMSMCs. Endoproteolytic digest of mK44 did not occur in HEK293 cells or mouse fibroblasts. MK44 truncated at a putative N-myristoylation site did not produce current when expressed alone, but formed a functional channel when co-expressed with the N-terminus. These findings provide novel insight into cell-specific regulation of maxi-K channel function.
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Affiliation(s)
- Victoria P Korovkina
- Department of Physiology and Biophysics, Carver College of Medicine, University of Iowa, 6-432 BSB Iowa City, IA 52242, USA
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Buchanan KT, Ames JB, Asfaw SH, Wingard JN, Olson CL, Campana PT, Araújo APU, Engman DM. A flagellum-specific calcium sensor. J Biol Chem 2005; 280:40104-11. [PMID: 16148003 DOI: 10.1074/jbc.m505777200] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The flagellar calcium-binding protein (FCaBP) of the flagellated protozoan Trypanosoma cruzi associates with the flagellar membrane via its N-terminal myristate and palmitate moieties in a calcium-modulated, conformation-dependent manner. This mechanism of localization is similar to that described for neuronal calcium sensors, which undergo calcium-dependent changes in conformation, which modulate the availability of the acyl groups for membrane interaction and partner association. To test whether FCaBP undergoes a calcium-dependent conformational change and to explore the role of such a change in flagellar targeting, we first introduced point mutations into each of the two EF-hand calcium-binding sites of FCaBP to define their affinities. Analysis of recombinant EF-3 mutant (E151Q), EF-4 mutant (E188Q), and double mutant proteins showed EF-3 to be the high affinity site (Kd approximately 9 microM) and EF-4 the low affinity site (Kd approximately 120 microM). These assignments also correlated with partial (E188Q), nearly complete (E151Q), and complete (E151Q,E188Q) disruption of calcium-induced conformational changes determined by NMR spectrometry. We next expressed the FCaBP E151Q mutant and the double mutant in T. cruzi epimastigotes. These transproteins localized to the flagellum, suggesting the existence of a calcium-dependent interaction of FCaBP that is independent of its intrinsic calcium binding capacity. Several proteins were identified by FCaBP affinity chromatography that interact with FCaBP in a calcium-dependent manner, but with differential dependence on calcium-binding by FCaBP. These findings may have broader implications for the calcium acyl switch mechanism of protein regulation.
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Affiliation(s)
- Kathryn T Buchanan
- Department of Pathology and Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
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50
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Komolov KE, Zinchenko DV, Churumova VA, Vaganova SA, Weiergräber OH, Senin II, Philippov PP, Koch KW. One of the Ca2+ binding sites of recoverin exclusively controls interaction with rhodopsin kinase. Biol Chem 2005; 386:285-9. [PMID: 15843174 DOI: 10.1515/bc.2005.034] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Recoverin is a neuronal calcium sensor protein that controls the activity of rhodopsin kinase in a Ca(2+)-dependent manner. Mutations in the EF-hand Ca2+ binding sites are valuable tools for investigating the functional properties of recoverin. In the recoverin mutant E121Q (Rec E121Q ) the high-affinity Ca2+ binding site is disabled. The non-myristoylated form of Rec E121Q binds one Ca2+ via its second Ca(2+)-binding site (EF-hand 2), whereas the myristoylated variant does not bind Ca2+ at all. Binding of Ca2+ to non-myristoylated Rec E121Q apparently triggers exposure of apolar side chains, allowing for association with hydrophobic matrices. Likewise, an interaction surface for the recoverin target rhodopsin kinase is constituted upon Ca2+ binding to the non-acylated mutant. Structural changes resulting from Ca(2+)-occupation of EF-hand 2 in myristoylated and non-myristoylated recoverin variants are discussed in terms of critical conditions required for biological activity.
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Affiliation(s)
- Konstantin E Komolov
- Institut für Biologische Informationsverarbeitung 1, Forschungszentrum Jülich, D-52425 Jülich, Germany
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