1
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Koch KW. Molecular tuning of calcium dependent processes by neuronal calcium sensor proteins in the retina. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2023; 1870:119491. [PMID: 37230154 DOI: 10.1016/j.bbamcr.2023.119491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 05/04/2023] [Accepted: 05/05/2023] [Indexed: 05/27/2023]
Abstract
Vertebrate photoreceptor cells are exquisite light detectors operating under very dim and bright illumination mediated by phototransduction, which is under control of the two secondary messengers cGMP and Ca2+. Feedback mechanisms enable photoreceptor cells to regain their responsiveness after light stimulation and involve neuronal Ca2+-sensor proteins, named GCAPs (guanylate cyclase-activating proteins) and recoverins. This review compares the diversity in Ca2+-related signaling mediated by GCAP and recoverin variants that exhibit differences in Ca2+-sensing, protein conformational changes, myristoyl switch mechanisms, diversity in divalent cation binding and dimer formation. In summary, both subclasses of neuronal Ca2+-sensor proteins contribute to a complex signaling network in rod and cone cells, which is perfectly suited to match the requirements for sensitive cell responses and maintaining this responsiveness in the presence of different background light intensities.
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Affiliation(s)
- Karl-Wilhelm Koch
- Department of Neuroscience, Division of Biochemistry, University of Oldenburg, 26111 Oldenburg, Germany.
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2
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Avesani A, Marino V, Zanzoni S, Koch KW, Dell'Orco D. Molecular properties of human guanylate cyclase-activating protein 2 (GCAP2) and its retinal dystrophy-associated variant G157R. J Biol Chem 2021; 296:100619. [PMID: 33812995 PMCID: PMC8113879 DOI: 10.1016/j.jbc.2021.100619] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Revised: 03/25/2021] [Accepted: 03/30/2021] [Indexed: 12/31/2022] Open
Abstract
In murine and bovine photoreceptors, guanylate cyclase-activating protein 2 (GCAP2) activates retinal guanylate cyclases (GCs) at low Ca2+ levels, thus contributing to the Ca2+/cGMP negative feedback on the cyclase together with its paralog guanylate cyclase-activating protein 1, which has the same function but different Ca2+ sensitivity. In humans, a GCAP2 missense mutation (G157R) has been associated with inherited retinal degeneration (IRD) via an unknown molecular mechanism. Here, we characterized the biochemical properties of human GCAP2 and the G157R variant, focusing on its dimerization and the Ca2+/Mg2+-binding processes in the presence or absence of N-terminal myristoylation. We found that human GCAP2 and its bovine/murine orthologs significantly differ in terms of oligomeric properties, cation binding, and GC regulation. Myristoylated GCAP2 endothermically binds up to 3 Mg2+ with high affinity and forms a compact dimer that may reversibly dissociate in the presence of Ca2+. Conversely, nonmyristoylated GCAP2 does not bind Mg2+ over the physiological range and remains as a monomer in the absence of Ca2+. Both myristoylated and nonmyristoylated GCAP2 bind Ca2+ with high affinity. At odds with guanylate cyclase-activating protein 1 and independently of myristoylation, human GCAP2 does not significantly activate retinal GC1 in a Ca2+-dependent fashion. The IRD-associated G157R variant is characterized by a partly misfolded, molten globule-like conformation with reduced affinity for cations and prone to form aggregates, likely mediated by hydrophobic interactions. Our findings suggest that GCAP2 might be mostly implicated in processes other than phototransduction in human photoreceptors and suggest a possible molecular mechanism for G157R-associated IRD.
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Affiliation(s)
- Anna Avesani
- Department of Neurosciences, Biomedicine and Movement Sciences, Biological Chemistry Section, University of Verona, Verona, Italy
| | - Valerio Marino
- Department of Neurosciences, Biomedicine and Movement Sciences, Biological Chemistry Section, University of Verona, Verona, Italy
| | - Serena Zanzoni
- Centro Piattaforme Tecnologiche, University of Verona, Verona, Italy
| | - Karl-Wilhelm Koch
- Department of Neuroscience, Division of Biochemistry, University of Oldenburg, Oldenburg, Germany
| | - Daniele Dell'Orco
- Department of Neurosciences, Biomedicine and Movement Sciences, Biological Chemistry Section, University of Verona, Verona, Italy.
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3
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Potvin-Fournier K, Valois-Paillard G, Lefèvre T, Cantin L, Salesse C, Auger M. Membrane fluidity is a driving force for recoverin myristoyl immobilization in zwitterionic lipids. Biochem Biophys Res Commun 2017; 490:1268-1273. [DOI: 10.1016/j.bbrc.2017.07.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 07/02/2017] [Indexed: 01/08/2023]
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4
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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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5
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Scheidt HA, Klingler J, Huster D, Keller S. Structural Thermodynamics of myr-Src(2-19) Binding to Phospholipid Membranes. Biophys J 2016; 109:586-94. [PMID: 26244740 DOI: 10.1016/j.bpj.2015.06.051] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Revised: 06/24/2015] [Accepted: 06/24/2015] [Indexed: 12/19/2022] Open
Abstract
Many proteins are anchored to lipid bilayer membranes through a combination of hydrophobic and electrostatic interactions. In the case of the membrane-bound nonreceptor tyrosine kinase Src from Rous sarcoma virus, these interactions are mediated by an N-terminal myristoyl chain and an adjacent cluster of six basic amino-acid residues, respectively. In contrast with the acyl modifications of other lipid-anchored proteins, the myristoyl chain of Src does not match the host lipid bilayer in terms of chain conformation and dynamics, which is attributed to a tradeoff between hydrophobic burial of the myristoyl chain and repulsion of the peptidic moiety from the phospholipid headgroup region. Here, we combine thermodynamic information obtained from isothermal titration calorimetry with structural data derived from (2)H, (13)C, and (31)P solid-state nuclear magnetic resonance spectroscopy to decipher the hydrophobic and electrostatic contributions governing the interactions of a myristoylated Src peptide with zwitterionic and anionic membranes made from lauroyl (C12:0) or myristoyl (C14:0) lipids. Although the latter are expected to enable better hydrophobic matching, the Src peptide partitions more avidly into the shorter-chain lipid analog because this does not require the myristoyl chain to stretch extensively to avoid unfavorable peptide/headgroup interactions. Moreover, we find that Coulombic and intrinsic contributions to membrane binding are not additive, because the presence of anionic lipids enhances membrane binding more strongly than would be expected on the basis of simple Coulombic attraction.
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Affiliation(s)
- Holger A Scheidt
- Institut für Medizinische Physik und Biophysik, Universität Leipzig, Leipzig, Germany
| | - Johannes Klingler
- Molecular Biophysics, University of Kaiserslautern, Kaiserslautern, Germany
| | - Daniel Huster
- Institut für Medizinische Physik und Biophysik, Universität Leipzig, Leipzig, Germany
| | - Sandro Keller
- Molecular Biophysics, University of Kaiserslautern, Kaiserslautern, Germany.
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6
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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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7
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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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8
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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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9
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Guanylate Cyclase-Activating Protein-2 Undergoes Structural Changes upon Binding to Detergent Micelles and Bicelles. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:2767-77. [DOI: 10.1016/j.bbamem.2014.07.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 07/11/2014] [Accepted: 07/14/2014] [Indexed: 11/23/2022]
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10
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Lim S, Dizhoor AM, Ames JB. Structural diversity of neuronal calcium sensor proteins and insights for activation of retinal guanylyl cyclase by GCAP1. Front Mol Neurosci 2014; 7:19. [PMID: 24672427 PMCID: PMC3956117 DOI: 10.3389/fnmol.2014.00019] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 02/27/2014] [Indexed: 01/08/2023] Open
Abstract
Neuronal calcium sensor (NCS) proteins, a sub-branch of the calmodulin superfamily, are expressed in the brain and retina where they transduce calcium signals and are genetically linked to degenerative diseases. The amino acid sequences of NCS proteins are highly conserved but their physiological functions are quite different. Retinal recoverin controls Ca2+-dependent inactivation of light-excited rhodopsin during phototransduction, guanylyl cyclase activating proteins 1 and 2 (GCAP1 and GCAP2) promote Ca2+-dependent activation of retinal guanylyl cyclases, and neuronal frequenin (NCS-1) modulates synaptic activity and neuronal secretion. Here we review the molecular structures of myristoylated forms of NCS-1, recoverin, and GCAP1 that all look very different, suggesting that the attached myristoyl group helps to refold these highly homologous proteins into different three-dimensional folds. Ca2+-binding to both recoverin and NCS-1 cause large protein conformational changes that ejects the covalently attached myristoyl group into the solvent exterior and promotes membrane targeting (Ca2+-myristoyl switch). The GCAP proteins undergo much smaller Ca2+-induced conformational changes and do not possess a Ca2+-myristoyl switch. Recent structures of GCAP1 in both its activator and Ca2+-bound inhibitory states will be discussed to understand structural determinants that control their Ca2+-dependent activation of retinal guanylyl cyclases.
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Affiliation(s)
- Sunghyuk Lim
- Department of Chemistry, University of California at Davis Davis, CA, USA
| | - Alexander M Dizhoor
- Basic Sciences, Pennsylvania College of Optometry, Salus University Elkins Park, PA, USA
| | - James B Ames
- Department of Chemistry, University of California at Davis Davis, CA, USA
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Mobius K, Nordsieck K, Pichert A, Samsonov SA, Thomas L, Schiller J, Kalkhof S, Teresa Pisabarro M, Beck-Sickinger AG, Huster D. Investigation of lysine side chain interactions of interleukin-8 with heparin and other glycosaminoglycans studied by a methylation-NMR approach. Glycobiology 2013; 23:1260-9. [DOI: 10.1093/glycob/cwt062] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
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12
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Nordsieck K, Pichert A, Samsonov SA, Thomas L, Berger C, Pisabarro MT, Huster D, Beck-Sickinger AG. Residue 75 of Interleukin-8 is Crucial for its Interactions with Glycosaminoglycans. Chembiochem 2012; 13:2558-66. [DOI: 10.1002/cbic.201200467] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2012] [Indexed: 12/22/2022]
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13
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Schlorke D, Thomas L, Samsonov SA, Huster D, Arnhold J, Pichert A. The influence of glycosaminoglycans on IL-8-mediated functions of neutrophils. Carbohydr Res 2012; 356:196-203. [DOI: 10.1016/j.carres.2012.02.025] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Revised: 02/21/2012] [Accepted: 02/24/2012] [Indexed: 02/07/2023]
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14
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Kollmann H, Becker SF, Shirdel J, Scholten A, Ostendorp A, Lienau C, Koch KW. Probing the Ca(2+) switch of the neuronal Ca(2+) sensor GCAP2 by time-resolved fluorescence spectroscopy. ACS Chem Biol 2012; 7:1006-14. [PMID: 22409623 DOI: 10.1021/cb3000748] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
We report fluorescence lifetime and rotational anisotropy measurements of the fluorescent dye Alexa647 attached to the guanylate cyclase-activating protein 2 (GCAP2), an intracellular myristoylated calcium sensor protein operating in photoreceptor cells. By linking the dye to different protein regions critical for monitoring calcium-induced conformational changes, we could measure fluorescence lifetimes and rotational correlation times as a function of myristoylation, calcium, and position of the attached dye, while GCAP2 was still able to regulate guanylate cyclase in a Ca(2+)-sensitive manner. We observe distinct site-specific variations in the fluorescence dynamics when externally changing the protein conformation. A clear reduction in fluorescence lifetime suggests that in the calcium-free state a dye marker in amino acid position 131 senses a more hydrophobic protein environment than in position 111. Saturating GCAP2 with calcium increases the fluorescence lifetime and hence leads to larger exposure of position 111 to the solvent and at the same time to a movement of position 131 into a hydrophobic protein cleft. In addition, we find distinct, biexponential anisotropy decays reflecting the reorientational motion of the fluorophore dipole and the dye/protein complex, respectively. Our experimental data are well described by a "wobbling-in-a-cone" model and reveal that for dye markers in position 111 of the GCAP2 protein both addition of calcium and myristoylation results in a pronounced increase in orientational flexibility of the fluorophore. Our results provide evidence that the up-and-down movement of an α-helix that is situated between position 111 and 131 is a key feature of the dynamics of the protein-dye complex. Operation of this piston-like movement is triggered by the intracellular messenger calcium.
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Affiliation(s)
- Heiko Kollmann
- Ultrafast
Nano-Optics, Institute of Physics and §Biochemistry, Institute of Biology and Environmental
Sciences, Faculty V, University of Oldenburg, D-26111 Oldenburg, Germany
- Center
of Interface Science and
- Research Center Neurosensory Science, University of Oldenburg, D-26111 Oldenburg, Germany
| | - Simon F. Becker
- Ultrafast
Nano-Optics, Institute of Physics and §Biochemistry, Institute of Biology and Environmental
Sciences, Faculty V, University of Oldenburg, D-26111 Oldenburg, Germany
- Center
of Interface Science and
- Research Center Neurosensory Science, University of Oldenburg, D-26111 Oldenburg, Germany
| | - Javid Shirdel
- Ultrafast
Nano-Optics, Institute of Physics and §Biochemistry, Institute of Biology and Environmental
Sciences, Faculty V, University of Oldenburg, D-26111 Oldenburg, Germany
- Center
of Interface Science and
- Research Center Neurosensory Science, University of Oldenburg, D-26111 Oldenburg, Germany
| | - Alexander Scholten
- Ultrafast
Nano-Optics, Institute of Physics and §Biochemistry, Institute of Biology and Environmental
Sciences, Faculty V, University of Oldenburg, D-26111 Oldenburg, Germany
- Center
of Interface Science and
- Research Center Neurosensory Science, University of Oldenburg, D-26111 Oldenburg, Germany
| | - Anna Ostendorp
- Ultrafast
Nano-Optics, Institute of Physics and §Biochemistry, Institute of Biology and Environmental
Sciences, Faculty V, University of Oldenburg, D-26111 Oldenburg, Germany
- Center
of Interface Science and
- Research Center Neurosensory Science, University of Oldenburg, D-26111 Oldenburg, Germany
| | - Christoph Lienau
- Ultrafast
Nano-Optics, Institute of Physics and §Biochemistry, Institute of Biology and Environmental
Sciences, Faculty V, University of Oldenburg, D-26111 Oldenburg, Germany
- Center
of Interface Science and
- Research Center Neurosensory Science, University of Oldenburg, D-26111 Oldenburg, Germany
| | - Karl-Wilhelm Koch
- Ultrafast
Nano-Optics, Institute of Physics and §Biochemistry, Institute of Biology and Environmental
Sciences, Faculty V, University of Oldenburg, D-26111 Oldenburg, Germany
- Center
of Interface Science and
- Research Center Neurosensory Science, University of Oldenburg, D-26111 Oldenburg, Germany
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15
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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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16
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Pichert A, Samsonov SA, Theisgen S, Thomas L, Baumann L, Schiller J, Beck-Sickinger AG, Huster D, Pisabarro MT. Characterization of the interaction of interleukin-8 with hyaluronan, chondroitin sulfate, dermatan sulfate and their sulfated derivatives by spectroscopy and molecular modeling. Glycobiology 2011; 22:134-45. [PMID: 21873605 PMCID: PMC3230280 DOI: 10.1093/glycob/cwr120] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The interactions between glycosaminoglycans (GAGs), important components of the extracellular matrix, and proteins such as growth factors and chemokines play critical roles in cellular regulation processes. Therefore, the design of GAG derivatives for the development of innovative materials with bio-like properties in terms of their interaction with regulatory proteins is of great interest for tissue engineering and regenerative medicine. Previous work on the chemokine interleukin-8 (IL-8) has focused on its interaction with heparin and heparan sulfate, which regulate chemokine function. However, the extracellular matrix contains other GAGs, such as hyaluronic acid (HA), dermatan sulfate (DS) and chondroitin sulfate (CS), which have so far not been characterized in terms of their distinct molecular recognition properties towards IL-8 in relation to their length and sulfation patterns. NMR and molecular modeling have been in great part the methods of choice to study the structural and recognition properties of GAGs and their protein complexes. However, separately these methods have challenges to cope with the high degree of similarity and flexibility that GAGs exhibit. In this work, we combine fluorescence spectroscopy, NMR experiments, docking and molecular dynamics simulations to study the configurational and recognition properties of IL-8 towards a series of HA and CS derivatives and DS. We analyze the effects of GAG length and sulfation patterns in binding strength and specificity, and the influence of GAG binding on IL-8 dimer formation. Our results highlight the importance of combining experimental and theoretical approaches to obtain a better understanding of the molecular recognition properties of GAG–protein systems.
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Affiliation(s)
- Annelie Pichert
- Institute of Medical Physics and Biophysics, University of Leipzig, Härtelstr. 16-18, D-04107 Leipzig, Germany
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A myristoyl/phosphoserine switch controls cAMP-dependent protein kinase association to membranes. J Mol Biol 2011; 411:823-36. [PMID: 21740913 DOI: 10.1016/j.jmb.2011.06.034] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Revised: 06/16/2011] [Accepted: 06/18/2011] [Indexed: 11/21/2022]
Abstract
The cAMP-dependent protein kinase [protein kinase A (PKA)] mediates a myriad of cellular signaling events, and its activity is tightly regulated in both space and time. Among these regulatory mechanisms is N-myristoylation, whose biological role has been elusive. Using a combination of thermodynamics, kinetics, and spectroscopic methods, we analyzed the effects of N-myristoylation and phosphorylation at Ser10 on the interactions of PKA with model membranes. We found that, in the absence of lipids, the myristoyl group is tucked into the hydrophobic binding pocket of the enzyme (myr-in state). Upon association with lipid bilayers, the myristoyl group is extruded and inserts into the hydrocarbon region of the lipid bilayer (myr-out state). NMR data indicate that the enzyme undergoes conformational equilibrium between myr-in and myr-out states, which can be shifted byeither interaction with membranes and/or phosphorylation at Ser10. Our results provide evidence that the membrane binding motif of the myristoylated C-subunit of PKA (PKA-C) steers the enzyme toward lipids independent of its regulatory subunit or an A-kinase anchoring protein, providing an additional mechanism to localize the enzyme near membrane-bound substrates.
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