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Léger C, Pitard I, Sadi M, Carvalho N, Brier S, Mechaly A, Raoux-Barbot D, Davi M, Hoos S, Weber P, Vachette P, Durand D, Haouz A, Guijarro JI, Ladant D, Chenal A. Dynamics and structural changes of calmodulin upon interaction with the antagonist calmidazolium. BMC Biol 2022; 20:176. [PMID: 35945584 PMCID: PMC9361521 DOI: 10.1186/s12915-022-01381-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 07/29/2022] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND Calmodulin (CaM) is an evolutionarily conserved eukaryotic multifunctional protein that functions as the major sensor of intracellular calcium signaling. Its calcium-modulated function regulates the activity of numerous effector proteins involved in a variety of physiological processes in diverse organs, from proliferation and apoptosis, to memory and immune responses. Due to the pleiotropic roles of CaM in normal and pathological cell functions, CaM antagonists are needed for fundamental studies as well as for potential therapeutic applications. Calmidazolium (CDZ) is a potent small molecule antagonist of CaM and one the most widely used inhibitors of CaM in cell biology. Yet, CDZ, as all other CaM antagonists described thus far, also affects additional cellular targets and its lack of selectivity hinders its application for dissecting calcium/CaM signaling. A better understanding of CaM:CDZ interaction is key to design analogs with improved selectivity. Here, we report a molecular characterization of CaM:CDZ complexes using an integrative structural biology approach combining SEC-SAXS, X-ray crystallography, HDX-MS, and NMR. RESULTS We provide evidence that binding of a single molecule of CDZ induces an open-to-closed conformational reorientation of the two domains of CaM and results in a strong stabilization of its structural elements associated with a reduction of protein dynamics over a large time range. These CDZ-triggered CaM changes mimic those induced by CaM-binding peptides derived from physiological protein targets, despite their distinct chemical natures. CaM residues in close contact with CDZ and involved in the stabilization of the CaM:CDZ complex have been identified. CONCLUSION Our results provide molecular insights into CDZ-induced dynamics and structural changes of CaM leading to its inhibition and open the way to the rational design of more selective CaM antagonists. Calmidazolium is a potent and widely used inhibitor of calmodulin, a major mediator of calcium-signaling in eukaryotic cells. Structural characterization of calmidazolium-binding to calmodulin reveals that it triggers open-to-closed conformational changes similar to those induced by calmodulin-binding peptides derived from enzyme targets. These results provide molecular insights into CDZ-induced dynamics and structural changes of CaM leading to its inhibition and open the way to the rational design of more selective CaM antagonists.
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Affiliation(s)
- Corentin Léger
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, Paris, 75015, France
| | - Irène Pitard
- Biological NMR and HDX-MS Technological Platform, CNRS UMR3528, Université Paris Cité, Institut Pasteur, Paris, 75015, France
| | - Mirko Sadi
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, Paris, 75015, France
- Université Paris Cité, Paris, France
| | - Nicolas Carvalho
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, Paris, 75015, France
- Université Paris Cité, Paris, France
| | - Sébastien Brier
- Biological NMR and HDX-MS Technological Platform, CNRS UMR3528, Université Paris Cité, Institut Pasteur, Paris, 75015, France
| | - Ariel Mechaly
- Plate-forme de Cristallographie-C2RT, Université Paris Cité, CNRS UMR3528, Institut Pasteur, Paris, France
| | - Dorothée Raoux-Barbot
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, Paris, 75015, France
| | - Maryline Davi
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, Paris, 75015, France
| | - Sylviane Hoos
- Plateforme de Biophysique Moléculaire, Université Paris Cité, CNRS UMR3528, Institut Pasteur, Paris, France
| | - Patrick Weber
- Plate-forme de Cristallographie-C2RT, Université Paris Cité, CNRS UMR3528, Institut Pasteur, Paris, France
| | - Patrice Vachette
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Dominique Durand
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Ahmed Haouz
- Plate-forme de Cristallographie-C2RT, Université Paris Cité, CNRS UMR3528, Institut Pasteur, Paris, France
| | - J Iñaki Guijarro
- Biological NMR and HDX-MS Technological Platform, CNRS UMR3528, Université Paris Cité, Institut Pasteur, Paris, 75015, France
| | - Daniel Ladant
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, Paris, 75015, France.
| | - Alexandre Chenal
- Biochemistry of Macromolecular Interactions Unit, Department of Structural Biology and Chemistry, CNRS UMR3528, Institut Pasteur, Paris, 75015, France.
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2
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Giles J, Lopez V, McConnaha E, Hayden M, Kragenbring C, Carli D, Wauson E, Tran QK. Regulation of basal autophagy by calmodulin availability. FEBS J 2022; 289:5322-5340. [PMID: 35285161 DOI: 10.1111/febs.16432] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Revised: 01/17/2022] [Accepted: 03/10/2022] [Indexed: 01/18/2023]
Abstract
Macroautophagy (hereafter autophagy) is a process that degrades cellular components to maintain homeostasis. The Ca2+ sensor calmodulin (CaM) regulates numerous cell functions but is a limiting factor due to its insufficient availability for all target proteins. However, evidence that CaM availability regulates basal autophagy is lacking. Here, we have tested this hypothesis. CaM antagonists W-7, trifluoperazine and CGS9343b cause autophagosome accumulation and inhibit basal autophagic flux in the same manner as does chloroquine. These reagents promote the activity of AMP-activated protein kinase (AMPK) but not that of the mechanistic target of rapamycin (mTOR). Competitive binding assays using CaM sensors with different Ca2+ dependencies showed that chloroquine directly binds CaM in a Ca2+ -dependent fashion. The CaM antagonists have disparate effects on cytoplasmic Ca2+ , triggering from none to robust signals, indicating that their consistent inhibition of autophagy is due to inhibition of CaM and not Ca2+ . Chelating intracellular Ca2+ reduces the effect of the CaM antagonists to accumulate LC3-II, indicating that they do so by inhibiting CaM-dependent activities at basal Ca2+ level. The CaM antagonists cause lysosomal alkalinisation. Consistently, buffering CaM with a high-affinity CaM-binding protein that binds CaM at resting Ca2+ level increases lysosomal pH. Enhanced CaM buffering using a chimeric protein that contains two high-affinity CaM-binding sites that can collectively bind CaM at a large range of Ca2+ further increases lysosomal pH and increases LC3-II accumulation and AMPK activity, but not that of mTOR. These data demonstrate that CaM availability is required for basal autophagy.
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Affiliation(s)
- Jennifer Giles
- Department of Physiology & Pharmacology, Des Moines University College of Osteopathic Medicine, IA, USA
| | - Vanessa Lopez
- Department of Physiology & Pharmacology, Des Moines University College of Osteopathic Medicine, IA, USA
| | - Elizabeth McConnaha
- Department of Physiology & Pharmacology, Des Moines University College of Osteopathic Medicine, IA, USA
| | - Matthew Hayden
- Department of Physiology & Pharmacology, Des Moines University College of Osteopathic Medicine, IA, USA
| | - Caleb Kragenbring
- Department of Physiology & Pharmacology, Des Moines University College of Osteopathic Medicine, IA, USA
| | - David Carli
- Department of Physiology & Pharmacology, Des Moines University College of Osteopathic Medicine, IA, USA
| | - Eric Wauson
- Department of Physiology & Pharmacology, Des Moines University College of Osteopathic Medicine, IA, USA
| | - Quang-Kim Tran
- Department of Physiology & Pharmacology, Des Moines University College of Osteopathic Medicine, IA, USA
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3
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Voegele A, Sadi M, O'Brien DP, Gehan P, Raoux‐Barbot D, Davi M, Hoos S, Brûlé S, Raynal B, Weber P, Mechaly A, Haouz A, Rodriguez N, Vachette P, Durand D, Brier S, Ladant D, Chenal A. A High-Affinity Calmodulin-Binding Site in the CyaA Toxin Translocation Domain is Essential for Invasion of Eukaryotic Cells. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:2003630. [PMID: 33977052 PMCID: PMC8097335 DOI: 10.1002/advs.202003630] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 12/10/2020] [Indexed: 06/12/2023]
Abstract
The molecular mechanisms and forces involved in the translocation of bacterial toxins into host cells are still a matter of intense research. The adenylate cyclase (CyaA) toxin from Bordetella pertussis displays a unique intoxication pathway in which its catalytic domain is directly translocated across target cell membranes. The CyaA translocation region contains a segment, P454 (residues 454-484), which exhibits membrane-active properties related to antimicrobial peptides. Herein, the results show that this peptide is able to translocate across membranes and to interact with calmodulin (CaM). Structural and biophysical analyses reveal the key residues of P454 involved in membrane destabilization and calmodulin binding. Mutational analysis demonstrates that these residues play a crucial role in CyaA translocation into target cells. In addition, calmidazolium, a calmodulin inhibitor, efficiently blocks CyaA internalization. It is proposed that after CyaA binding to target cells, the P454 segment destabilizes the plasma membrane, translocates across the lipid bilayer and binds calmodulin. Trapping of CyaA by the CaM:P454 interaction in the cytosol may assist the entry of the N-terminal catalytic domain by converting the stochastic motion of the polypeptide chain through the membrane into an efficient vectorial chain translocation into host cells.
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Affiliation(s)
- Alexis Voegele
- Biochemistry of Macromolecular Interactions UnitDepartment of Structural Biology and ChemistryInstitut PasteurCNRS UMR3528Paris75015France
- Université de ParisSorbonne Paris CitéParis75006France
| | - Mirko Sadi
- Biochemistry of Macromolecular Interactions UnitDepartment of Structural Biology and ChemistryInstitut PasteurCNRS UMR3528Paris75015France
- Université de ParisSorbonne Paris CitéParis75006France
| | - Darragh Patrick O'Brien
- Biochemistry of Macromolecular Interactions UnitDepartment of Structural Biology and ChemistryInstitut PasteurCNRS UMR3528Paris75015France
| | - Pauline Gehan
- Sorbonne UniversitéÉcole normale supérieurePSL UniversityCNRSLaboratoire des biomoléculesLBMParis75005France
| | - Dorothée Raoux‐Barbot
- Biochemistry of Macromolecular Interactions UnitDepartment of Structural Biology and ChemistryInstitut PasteurCNRS UMR3528Paris75015France
| | - Maryline Davi
- Biochemistry of Macromolecular Interactions UnitDepartment of Structural Biology and ChemistryInstitut PasteurCNRS UMR3528Paris75015France
| | - Sylviane Hoos
- Plateforme de Biophysique MoléculaireInstitut PasteurUMR 3528 CNRSParis75015France
| | - Sébastien Brûlé
- Plateforme de Biophysique MoléculaireInstitut PasteurUMR 3528 CNRSParis75015France
| | - Bertrand Raynal
- Plateforme de Biophysique MoléculaireInstitut PasteurUMR 3528 CNRSParis75015France
| | - Patrick Weber
- Institut PasteurPlate‐forme de cristallographie‐C2RTUMR‐3528 CNRSParis75015France
| | - Ariel Mechaly
- Institut PasteurPlate‐forme de cristallographie‐C2RTUMR‐3528 CNRSParis75015France
| | - Ahmed Haouz
- Institut PasteurPlate‐forme de cristallographie‐C2RTUMR‐3528 CNRSParis75015France
| | - Nicolas Rodriguez
- Sorbonne UniversitéÉcole normale supérieurePSL UniversityCNRSLaboratoire des biomoléculesLBMParis75005France
| | - Patrice Vachette
- Université Paris‐SaclayCEACNRSInstitute for Integrative Biology of the Cell (I2BC)Gif‐sur‐Yvette91198France
| | - Dominique Durand
- Université Paris‐SaclayCEACNRSInstitute for Integrative Biology of the Cell (I2BC)Gif‐sur‐Yvette91198France
| | - Sébastien Brier
- Biological NMR Technological PlateformCenter for Technological Resources and ResearchDepartment of Structural Biology and ChemistryInstitut PasteurCNRS UMR3528Paris75015France
| | - Daniel Ladant
- Biochemistry of Macromolecular Interactions UnitDepartment of Structural Biology and ChemistryInstitut PasteurCNRS UMR3528Paris75015France
| | - Alexandre Chenal
- Biochemistry of Macromolecular Interactions UnitDepartment of Structural Biology and ChemistryInstitut PasteurCNRS UMR3528Paris75015France
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Jalalypour F, Sensoy O, Atilgan C. Perturb-Scan-Pull: A Novel Method Facilitating Conformational Transitions in Proteins. J Chem Theory Comput 2020; 16:3825-3841. [PMID: 32324386 DOI: 10.1021/acs.jctc.9b01222] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Conformational transitions in proteins facilitate precise physiological functions. Therefore, it is crucial to understand the mechanisms underlying these processes to modulate protein function. Yet, studying structural and dynamical properties of proteins is notoriously challenging due to the complexity of the underlying potential energy surfaces (PES). We have previously developed the perturbation-response scanning (PRS) method to identify key residues that participate in the communication network responsible for specific conformational transitions. PRS is based on a residue-by-residue scan of the protein to determine the subset of residues/forces which provide the closest conformational change leading to a target conformational state, inasmuch as linear response theory applies to these motions. Here, we develop a novel method to further evaluate if conformational transitions may be triggered on the PES. We aim to study functionally relevant conformational transitions in proteins by using results obtained from PRS and feeding them as inputs to steered molecular dynamics simulations. The success and the transferability of the method are evaluated on three protein systems having different complexities of motion on the PES: calmodulin, adenylate kinase, and bacterial ferric binding protein. We find that the method captures the target conformation, while providing key residues and the optimum paths with relatively low free energy profiles.
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Affiliation(s)
- Farzaneh Jalalypour
- Faculty of Engineering and Natural Sciences, Sabanci University, 34956, Istanbul, Turkey
| | - Ozge Sensoy
- School of Engineering and Natural Sciences, Istanbul Medipol University, 34810, Istanbul, Turkey
| | - Canan Atilgan
- Faculty of Engineering and Natural Sciences, Sabanci University, 34956, Istanbul, Turkey.,Sabanci University Nanotechnology Research and Application Center, SUNUM, 34956, Istanbul, Turkey
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5
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The KN-93 Molecule Inhibits Calcium/Calmodulin-Dependent Protein Kinase II (CaMKII) Activity by Binding to Ca 2+/CaM. J Mol Biol 2019; 431:1440-1459. [PMID: 30753871 DOI: 10.1016/j.jmb.2019.02.001] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 12/14/2018] [Accepted: 02/04/2019] [Indexed: 12/22/2022]
Abstract
Calcium/calmodulin-dependent protein kinase II (CaMKII) is a multifunctional serine/threonine protein kinase that transmits calcium signals in various cellular processes. CaMKII is activated by calcium-bound calmodulin (Ca2+/CaM) through a direct binding mechanism involving a regulatory C-terminal α-helix in CaMKII. The Ca2+/CaM binding triggers transphosphorylation of critical threonine residues proximal to the CaM-binding site leading to the autoactivated state of CaMKII. The demonstration of its critical roles in pathophysiological processes has elevated CaMKII to a key target in the management of numerous diseases. The molecule KN-93 is the most widely used inhibitor for studying the cellular and in vivo functions of CaMKII. It is widely believed that KN-93 binds directly to CaMKII, thus preventing kinase activation by competing with Ca2+/CaM. Herein, we employed surface plasmon resonance, NMR, and isothermal titration calorimetry to characterize this presumed interaction. Our results revealed that KN-93 binds directly to Ca2+/CaM and not to CaMKII. This binding would disrupt the ability of Ca2+/CaM to interact with CaMKII, effectively inhibiting CaMKII activation. Our findings also indicated that KN-93 can specifically compete with a CaMKIIδ-derived peptide for binding to Ca2+/CaM. As indicated by the surface plasmon resonance and isothermal titration calorimetry data, apparently at least two KN-93 molecules can bind to Ca2+/CaM. Our findings provide new insight into how in vitro and in vivo data obtained with KN-93 should be interpreted. They further suggest that other Ca2+/CaM-dependent, non-CaMKII activities should be considered in KN-93-based mechanism-of-action studies and drug discovery efforts.
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6
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Mukherjee R, Bhattacharya A, Sau A, Basu S, Chakrabarti S, Chakrabarti O. Calmodulin regulates MGRN1-GP78 interaction mediated ubiquitin proteasomal degradation system. FASEB J 2018; 33:1927-1945. [PMID: 30230921 DOI: 10.1096/fj.201701413rrr] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The mechanism by which the endoplasmic reticulum (ER) ubiquitin ligases sense stress to potentiate their activity is poorly understood. GP78, an ER E3 ligase, is best known for its role in ER-associated protein degradation, although its activity is also linked to mitophagy, ER-mitochondria junctions, and MAPK signaling, thus highlighting the importance of understanding its regulation. In healthy cells, Mahogunin really interesting new gene (RING) finger 1 (MGRN1) interacts with GP78 and proteasomally degrades it to alleviate mitophagy. Here, we identify calmodulin (CaM) as the adapter protein that senses fluctuating cytosolic Ca2+ levels and modulates the Ca2+-dependent MGRN1-GP78 interactions. When stress elevates cytosolic Ca2+ levels in cultured and primary neuronal cells, CaM binds to both E3 ligases and inhibits their interaction. Molecular docking, simulation, and biophysical studies show that CaM interacts with both proteins with different affinities and binding modes. The physiological impact of this interaction switch manifests in the regulation of ER-associated protein degradation, ER-mitochondria junctions, and relative distribution of smooth ER and rough ER.-Mukherjee, R., Bhattacharya, A., Sau, A., Basu, S., Chakrabarti, S., Chakrabarti, O. Calmodulin regulates MGRN1-GP78 interaction mediated ubiquitin proteasomal degradation system.
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Affiliation(s)
- Rukmini Mukherjee
- Biophysics and Structural Genomics Division, Saha Institute of Nuclear Physics, Kolkata, India.,Buchmann Institute for Molecular Life Sciences, Frankfurt Am Main, Germany
| | - Anshu Bhattacharya
- Structural Biology and Bioinformatics Division, Council of Scientific and Industrial Research-Indian Institute of Chemical Biology (CSIB-IICB), Kolkata, India
| | - Abhishek Sau
- Chemical Sciences Division, Saha Institute of Nuclear Physics, Kolkata, India
| | - Samita Basu
- Chemical Sciences Division, Saha Institute of Nuclear Physics, Kolkata, India.,Homi Bhabha National Institute, Mumbai, India
| | - Saikat Chakrabarti
- Structural Biology and Bioinformatics Division, Council of Scientific and Industrial Research-Indian Institute of Chemical Biology (CSIB-IICB), Kolkata, India
| | - Oishee Chakrabarti
- Biophysics and Structural Genomics Division, Saha Institute of Nuclear Physics, Kolkata, India.,Homi Bhabha National Institute, Mumbai, India
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Haiech J, Gendrault Y, Kilhoffer MC, Ranjeva R, Madec M, Lallement C. A general framework improving teaching ligand binding to a macromolecule. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:2348-55. [PMID: 24657812 DOI: 10.1016/j.bbamcr.2014.03.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Revised: 03/10/2014] [Accepted: 03/13/2014] [Indexed: 10/25/2022]
Abstract
The interaction of a ligand with a macromolecule has been modeled following different theories. The tenants of the induced fit model consider that upon ligand binding, the protein-ligand complex undergoes a conformational change. In contrast, the allosteric model assumes that only one among different coexisting conformers of a given protein is suitable to bind the ligand optimally. In the present paper, we propose a general framework to model the binding of ligands to a macromolecule. Such framework built on the binding polynomial allows opening new ways to teach in a unified manner ligand binding, enzymology and receptor binding in pharmacology. Moreover, we have developed simple software that allows building the binding polynomial from the schematic description of the biological system under study. Taking calmodulin as a canonical example, we show here that the proposed tool allows the easy retrieval of previously experimental and computational reports. This article is part of a Special Issue entitled: Calcium Signaling in Health and Disease. Guest Editors: Geert Bultynck, Jacques Haiech, Claus W. Heizmann, Joachim Krebs, and Marc Moreau.
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Affiliation(s)
- Jacques Haiech
- LIT, Therapeutic Innovation Laboratory, UMR7200 CNRS, University of Strasbourg, Faculty of Pharmacy, Illkirch, France.
| | - Yves Gendrault
- ICube, Engineering, Computer and Imaging Science Laboratory, UMR7357 CNRS, University of Strasbourg, Telecom - Strasbourg, France
| | - Marie-Claude Kilhoffer
- LIT, Therapeutic Innovation Laboratory, UMR7200 CNRS, University of Strasbourg, Faculty of Pharmacy, Illkirch, France
| | - Raoul Ranjeva
- LIT, Therapeutic Innovation Laboratory, UMR7200 CNRS, University of Strasbourg, Faculty of Pharmacy, Illkirch, France
| | - Morgan Madec
- ICube, Engineering, Computer and Imaging Science Laboratory, UMR7357 CNRS, University of Strasbourg, Telecom - Strasbourg, France
| | - Christophe Lallement
- ICube, Engineering, Computer and Imaging Science Laboratory, UMR7357 CNRS, University of Strasbourg, Telecom - Strasbourg, France
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Audran E, Dagher R, Gioria S, Tsvetkov PO, Kulikova AA, Didier B, Villa P, Makarov AA, Kilhoffer MC, Haiech J. A general framework to characterize inhibitors of calmodulin: use of calmodulin inhibitors to study the interaction between calmodulin and its calmodulin binding domains. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:1720-31. [PMID: 23333870 DOI: 10.1016/j.bbamcr.2013.01.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2012] [Revised: 01/01/2013] [Accepted: 01/03/2013] [Indexed: 01/29/2023]
Abstract
The prominent role of Ca(2+) in cell physiology is mediated by a whole set of proteins involved in Ca(2+)-signal generation, deciphering and arrest. Among these intracellular proteins, calmodulin (CaM) known as a prototypical calcium sensor, serves as a ubiquitous carrier of the intracellular calcium signal in all eukaryotic cell types. CaM is assumed to be involved in many diseases including Parkinson, Alzheimer, and rheumatoid arthritis. Defects in some of many reaction partners of CaM might be responsible for disease symptoms. Several classes of drugs bind to CaM with unwanted side effects rather than specific therapeutic use. Thus, it may be more promising to concentrate at searching for pharmacological interferences with the CaM target proteins, in order to find tools for dissecting and investigating CaM-regulatory and modulatory functions in cells. In the present study, we have established a screening assay based on fluorescence polarization (FP) to identify a diverse set of small molecules that disrupt the regulatory function of CaM. The FP-based CaM assay consists in the competition of two fluorescent probes and a library of chemical compounds for binding to CaM. Screening of about 5300 compounds (Strasbourg Academic Library) by displacement of the probe yielded 39 compounds in a first step, from which 6 were selected. Those 6 compounds were characterized by means of calorimetry studies and by competitive displacement of two fluorescent probes interacting with CaM. Moreover, those small molecules were tested for their capability to displace 8 different CaM binding domains from CaM. Our results show that these CaM/small molecules interactions are not functionally equivalent. The strategy that has been set up for CaM is a general model for the development and validation of other CaM interactors, to decipher their mode of action, or rationally design more specific CaM antagonists. Moreover, this strategy may be used for other protein binding assays intended to screen for molecules with preferred binding activity. This article is part of a Special Issue entitled: 12th European Symposium on Calcium.
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Haiech J, Audran E, Fève M, Ranjeva R, Kilhoffer MC. Revisiting intracellular calcium signaling semantics. Biochimie 2011; 93:2029-37. [DOI: 10.1016/j.biochi.2011.05.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2011] [Accepted: 05/06/2011] [Indexed: 10/18/2022]
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10
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Effects of external calcium on the biotransformation of ginsenoside Rb1 to ginsenoside Rd by Paecilomyces bainier 229-7. World J Microbiol Biotechnol 2011; 28:857-63. [DOI: 10.1007/s11274-011-0882-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Accepted: 09/05/2011] [Indexed: 01/29/2023]
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11
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Amelot N, Carrouche A, Danoun S, Bourque S, Haiech J, Pugin A, Ranjeva R, Grima-Pettenati J, Mazars C, Briere C. Cryptogein, a fungal elicitor, remodels the phenylpropanoid metabolism of tobacco cell suspension cultures in a calcium-dependent manner. PLANT, CELL & ENVIRONMENT 2011; 34:149-61. [PMID: 20946589 DOI: 10.1111/j.1365-3040.2010.02233.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Plant cells use calcium-based signalling pathways to transduce biotic and/or abiotic stimuli into adaptive responses. However, little is known about the coupling between calcium signalling, transcriptional regulation and the downstream biochemical processes. To understand these relationships better, we challenged tobacco BY-2 cells with cryptogein and evaluated how calcium transients (monitored through the calcium sensor aequorin) impact (1) transcript levels of phenylpropanoid genes (assessed by RT-qPCR); and (2) derived-phenolic compounds (analysed by mass spectrometry). Most genes of the phenylpropanoid pathway were up-regulated by cryptogein and cell wall-bound phenolic compounds accumulated (mainly 5-hydroxyferulic acid). The accumulation of both transcripts and phenolics was calcium-dependent. The transcriptional regulation of phenylpropanoid genes was correlated in a non-linear manner with stimulus intensity and with components of the cryptogein-induced calcium signature. In addition, calmodulin inhibitors increased the sensitivity of cells to low concentrations of cryptogein. These results led us to propose a model of coupling between the cryptogein signal, calcium signalling and the transcriptional response, exerting control of transcription through the coordinated action of two decoding modules exerting opposite effects.
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Affiliation(s)
- Nicolas Amelot
- Université de Toulouse, UPS, UMR 5546 Surfaces Cellulaires et Signalisation chez les Végétaux, BP 42617, F-31326, Castanet-Tolosan, France
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12
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Colomer J, Schmitt AA, Toone EJ, Means AR. Identification and inhibitory properties of a novel Ca(2+)/calmodulin antagonist. Biochemistry 2010; 49:4244-54. [PMID: 20392081 DOI: 10.1021/bi1001213] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We developed a high-throughput yeast-based assay to screen for chemical inhibitors of Ca(2+)/calmodulin-dependent kinase pathways. After screening two small libraries, we identified the novel antagonist 125-C9, a substituted ethyleneamine. In vitro kinase assays confirmed that 125-C9 inhibited several calmodulin-dependent kinases (CaMKs) competitively with Ca(2+)/calmodulin (Ca(2+)/CaM). This suggested that 125-C9 acted as an antagonist for Ca(2+)/CaM rather than for CaMKs. We confirmed this hypothesis by showing that 125-C9 binds directly to Ca(2+)/CaM using isothermal titration calorimetry. We further characterized binding of 125-C9 to Ca(2+)/CaM and compared its properties with those of two well-studied CaM antagonists: trifluoperazine (TFP) and W-13. Isothermal titration calorimetry revealed that binding of 125-C9 to CaM is absolutely Ca(2+)-dependent, likely occurs with a stoichiometry of five 125-C9 molecules to one CaM molecule, and involves an exchange of two protons at pH 7.0. Binding of 125-C9 is driven overall by entropy and appears to be competitive with TFP and W-13, which is consistent with occupation of similar binding sites. To test the effects of 125-C9 in living cells, we evaluated mitogen-stimulated re-entry of quiescent cells into proliferation and found similar, although slightly better, levels of inhibition by 125-C9 than by TFP and W-13. Our results not only define a novel Ca(2+)/CaM inhibitor but also reveal that chemically unique CaM antagonists can bind CaM by distinct mechanisms but similarly inhibit cellular actions of CaM.
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Affiliation(s)
- Josep Colomer
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, P.O. Box 3813, Durham, North Carolina 27710, USA
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