The Experts below are selected from a list of 249 Experts worldwide ranked by ideXlab platform
Martin Biel - One of the best experts on this subject based on the ideXlab platform.
-
Cyclic Nucleotide-Regulated Cation Channels
Encyclopedia of Biological Chemistry, 2013Co-Authors: Martin BielAbstract:Cyclic Nucleotide-regulated cation channels are ion channels whose activation is regulated by the direct binding of Cyclic adenosine monophosphate or Cyclic guanosine monophosphate to the channel protein. Two structurally related families of channels regulated by Cyclic Nucleotides have been identified, the Cyclic Nucleotide-gated (CNG) channels and the hyperpolarization-activated Cyclic Nucleotide-gated (HCN) channels. CNG channels play a key role in visual and olfactory transduction. HCN channels are present in the conduction system of the heart and are involved in the control of cardiac automaticity. Moreover, these channels are widely expressed in central and peripheral neurons where they control a variety of fundamental processes.
-
regulation of hyperpolarization activated Cyclic Nucleotide gated hcn channel activity by ccmp
Journal of Biological Chemistry, 2012Co-Authors: Xiangang Zong, Christian Gruner, Xiaochun Caoehlker, Stefanie Fenske, Christian Wahlschott, Jens Krüger, Chengchang Chen, S Krause, Martin BielAbstract:Abstract Activation of hyperpolarization-activated Cyclic Nucleotide-gated (HCN) channels is facilitated in vivo by direct binding of the second messenger cAMP. This process plays a fundamental role in the fine tuning of HCN channel activity and is critical for the modulation of cardiac and neuronal rhythmicity. Here, we identify the pyrimidine Cyclic Nucleotide, Cyclic cytidine 3′, 5′-monophosphate (cCMP) as another regulator of HCN channels. We demonstrate that cCMP shifts the activation curves of two members of the HCN channel family, HCN2 and HCN4, to more depolarized voltages. Moreover, cCMP speeds up activation and slows down deactivation kinetics of these channels. The two other members of the HCN channel family, HCN1 and HCN3, are not sensitive to cCMP. The modulatory effect of cCMP is reversible and requires the presence of a functional Cyclic Nucleotide binding domain. We determined EC50 values of around 30 μM for cCMP as compared to 1 μM for cAMP. Notably, cCMP is a partial agonist of HCN channels displaying an efficacy of about 0.6. Cyclic CMP increased the frequency of pacemaker potentials from isolated sinoatrial pacemaker cells in presence of endogenous cAMP concentrations. Electrophysiological recordings indicated that this increase was caused by a depolarizing shift of the activation curve of the native HCN current which in turn leads to an enhancement of the slope of the diastolic depolarization of SAN cells. In conclusion, our findings establish cCMP as gating regulator of HCN channels and indicate that this Cyclic Nucleotide has to be considered in HCN channel regulated processes.
-
Cyclic Nucleotide gated channels.
Handbook of experimental pharmacology, 2009Co-Authors: Martin Biel, Stylianos MichalakisAbstract:Cyclic Nucleotide-gated (CNG) channels are ion channels which are activated by the binding of cGMP or cAMP. The channels are important cellular switches which transduce changes in intracellular concentrations of Cyclic Nucleotides into changes of the membrane potential and the Ca2+ concentration. CNG channels play a central role in the signal transduction pathways of vision and olfaction. Structurally, the channels belong to the superfamily of pore-loop cation channels. They share a common domain structure with hyperpolarization-activated Cyclic Nucleotide-gated (HCN) channels and Eag-like K+ channels. In this chapter, we give an overview on the molecular properties of CNG channels and describe the signal transduction pathways these channels are involved in. We will also summarize recent insights into the physiological and pathophysiological role of CNG channel proteins that have emerged from the analysis of CNG channel-deficient mouse models and human channelopathies.
-
Cyclic Nucleotide-regulated Cation Channels
The Journal of biological chemistry, 2008Co-Authors: Martin BielAbstract:Cyclic Nucleotide-regulated cation channels are ion channels whose activation is regulated by the direct binding of cAMP or cGMP to the channel protein. Two structurally related families of channels regulated by Cyclic Nucleotides have been identified, the Cyclic Nucleotide-gated channels and the hyperpolarization-activated Cyclic Nucleotide-gated channels. Cyclic Nucleotide-gated channels play a key role in visual and olfactory transduction. Hyperpolarization-activated Cyclic Nucleotide-gated channels are present in the conduction system of the heart and are involved in the control of cardiac automaticity. Moreover, these channels are widely expressed in central and peripheral neurons, where they control a variety of fundamental processes.
-
International Union of Pharmacology. XLII. Compendium of Voltage-Gated Ion Channels: Cyclic Nucleotide-Modulated Channels
Pharmacological Reviews, 2003Co-Authors: Franz Hofmann, Martin Biel, U. Benjamin KauppAbstract:This summary article presents an overview of the molecular relationships among the voltage-gated Cyclic Nucleotide-modulated channels and a standard nomenclature for them, which is derived from the IUPHAR Compendium of Voltage-Gated Ion Channels. The complete Compendium, including data tables for each member of the Cyclic Nucleotide-modulated channel family can be found at http://www.iuphar-db.org/iuphar-ic/.
Joe Beavo - One of the best experts on this subject based on the ideXlab platform.
-
biochemistry and physiology of Cyclic Nucleotide phosphodiesterases essential components in Cyclic Nucleotide signaling
Annual Review of Biochemistry, 2007Co-Authors: Marco Conti, Joe BeavoAbstract:AbstractAlthough Cyclic Nucleotide phosphodiesterases (PDEs) were described soon after the discovery of cAMP, their complexity and functions in signaling is only recently beginning to become fully realized. We now know that at least 100 different PDE proteins degrade cAMP and cGMP in eukaryotes. A complex PDE gene organization and a large number of PDE splicing variants serve to fine-tune Cyclic Nucleotide signals and contribute to specificity in signaling. Here we review some of the major concepts related to our understanding of PDE function and regulation including: (a) the structure of catalytic and regulatory domains and arrangement in holoenzymes; (b) PDE integration into signaling complexes; (c) the nature and function of negative and positive feedback circuits that have been conserved in PDEs from prokaryotes to human; (d) the emerging association of mutant PDE alleles with inherited diseases; and (e) the role of PDEs in generating subcellular signaling compartments.
-
Cyclic Nucleotide phosphodiesterases
xPharm: The Comprehensive Pharmacology Reference, 2007Co-Authors: Joe BeavoAbstract:Cyclic Nucleotide phosphodiesterases (PDEs) are a family of enzymes that function to terminate the action of the hormone …
-
Cyclic Nucleotide Phosphodiesterases in Health and Disease - Cyclic Nucleotide Phosphodiesterases in Health and Disease
2006Co-Authors: Joe Beavo, Sharron H. Francis, Miles D HouslayAbstract:Cyclic Nucleotide Phosphodiesterase Superfamily, J. A. Beavo, M. D. Houslay, and S. H. Francis Phosphodiesterase Isoforms-An Annotated List, G. B. Bolger Section A Specific Phosphodiesterase Families-Regulation, Molecular and Biochemical Characteristics Calmodulin-Stimulated Cyclic Nucleotide Phosphodiesterases, A. T. Bender PDE2 Structure and Functions, S. E. Martinez Phosphodiesterase 3B: An Important Regulator of Energy Homeostasis, E. Degerman and V. Manganiello Cellular Functions of PDE4 Enzymes, G. B. Bolger, M. Conti, and M. D. Houslay Phosphodiesterase 5: Molecular Characteristics Relating to Structure, Function, and Regulation, S. H. Francis, R. Zoraghi, J. Kotera, H. Ke, E. P. Bessay, M. A. Blount, and J. D. Corbin Photoreceptor Phosphodiesterase (PDE6): A G-Protein-Activated PDE Regulating Visual Excitation in Rod and Cone Photoreceptor Cells, R. H. Cote PDE7, T. Michaeli cAMP-Phosphodiesterase PDE 8 , V. Vasta PDE9, J. Kotera and K. Omori PDE10A: A Striatum Enriched, Dual-Substrate Phosphodiesterase, C. A. Strick, C. J. Schmidt, and F. S. Menniti PDE11, K. Omori and J. Kotera Section B Nonmammalian Phosphodiesterases Protozoal Phosphodiesterases, L.Wentzinger and T. Seebeck Studies of Phosphodiesterase Function Using Fruit Fly Genomics and Transgenics, S. A. Davies and J. P. Day Section C Phosphodiesterases Functional Significance: Gene-Targeted Knockout Strategies Insights into the Physiological Functions of PDE4 from Knockout Mice, S. L. C. Jin, W. Richter, and M. Conti Regulation of cAMP Level by PDE3B-Physiological Implications in Energy Balance and Insulin Secretion, A. Z. Zhao and L. Stenson Holst Section D Compartmentation in Cyclic Nucleotide Signaling Heart Failure, Fibrosis, and Cyclic Nucleotide Metabolism in Cardiac Fibroblasts, S. A. Epperson and L. L. Brunton Role of A-Kinase Anchoring Proteins in the Compartmentation in Cyclic Nucleotide Signaling, O. Witczak, E. M. Aandahl, and K. Tasken Role of Phosphodiesterases in Cyclic Nucleotide Compartmentation in Cardiac Myocytes, A. Abi-Gerges, L. R.V. Castro, F. Rochais, G. Vandecasteele, and R. Fischmeister Section E Phosphodiesterases as Pharmacological Targets in Disease Processes Role of PDEs in Vascular Health and Disease: Endothelial PDEs and Angiogenesis, T. Keravis, A. P. Silva, L. Favot, and C. Lugnier Regulation of PDE Expression in Arteries: Role in Controlling Vascular Cyclic Nucleotide Signaling, D. H. Maurice and D. G. Tilley Regulation and Function of Cyclic Nucleotide Phosphodiesterases in Vascular Smooth Muscle and Vascular Diseases, C. Yan, D. J. Nagel, and K. Jeon Role of Cyclic Nucleotide Phosphodiesterases in Heart Failure and Hypertension, M. A. Movsesian and C. J. Smith Molecular Determinants in Pulmonary Hypertension: The Role of PDE5, N.J. Pyne, F. Murray, R. Tate, and M.R. MacLean Role of PDE5 in Migraine, C. Kruuse Phosphodiesterase-4 as a Pharmacological Target Mediating Antidepressant and Cognitive Effects on Behavior, H. T. Zhang and J. M. O'Donnell Role of Phosphodiesterases in Apoptosis, A. Lerner, E. Y.Moon, and S. Tiwari Section F Development of Specific Phosphodiesterase Inhibitors as Therapeutic Agents Crystal Structure of Phosphodiesterase Families and the Potential for Rational Drug Design, K. Y. J. Zhang Structure, Catalytic Mechanism, and Inhibitor Selectivity of Cyclic Nucleotide Phosphodiesterases, H. Ke and H. Wang Bench to Bedside: Multiple Actions of the PDE3 Inhibitor Cilostazol, J. Kambayashi, Y. Shakur, and Y. Liu Reinventing the Wheel: Nonselective Phosphodiesterase Inhibitors for Chronic Inflammatory Diseases, M. A. Giembycz Medicinal Chemistry of PDE4 Inhibitors, J. M. McKenna and G. W. Muller Index
-
Cyclic Nucleotide phosphodiesterases in health and disease
2006Co-Authors: Joe Beavo, Sharron H. Francis, Miles D HouslayAbstract:Cyclic Nucleotide Phosphodiesterase Superfamily, J. A. Beavo, M. D. Houslay, and S. H. Francis Phosphodiesterase Isoforms-An Annotated List, G. B. Bolger Section A Specific Phosphodiesterase Families-Regulation, Molecular and Biochemical Characteristics Calmodulin-Stimulated Cyclic Nucleotide Phosphodiesterases, A. T. Bender PDE2 Structure and Functions, S. E. Martinez Phosphodiesterase 3B: An Important Regulator of Energy Homeostasis, E. Degerman and V. Manganiello Cellular Functions of PDE4 Enzymes, G. B. Bolger, M. Conti, and M. D. Houslay Phosphodiesterase 5: Molecular Characteristics Relating to Structure, Function, and Regulation, S. H. Francis, R. Zoraghi, J. Kotera, H. Ke, E. P. Bessay, M. A. Blount, and J. D. Corbin Photoreceptor Phosphodiesterase (PDE6): A G-Protein-Activated PDE Regulating Visual Excitation in Rod and Cone Photoreceptor Cells, R. H. Cote PDE7, T. Michaeli cAMP-Phosphodiesterase PDE 8 , V. Vasta PDE9, J. Kotera and K. Omori PDE10A: A Striatum Enriched, Dual-Substrate Phosphodiesterase, C. A. Strick, C. J. Schmidt, and F. S. Menniti PDE11, K. Omori and J. Kotera Section B Nonmammalian Phosphodiesterases Protozoal Phosphodiesterases, L.Wentzinger and T. Seebeck Studies of Phosphodiesterase Function Using Fruit Fly Genomics and Transgenics, S. A. Davies and J. P. Day Section C Phosphodiesterases Functional Significance: Gene-Targeted Knockout Strategies Insights into the Physiological Functions of PDE4 from Knockout Mice, S. L. C. Jin, W. Richter, and M. Conti Regulation of cAMP Level by PDE3B-Physiological Implications in Energy Balance and Insulin Secretion, A. Z. Zhao and L. Stenson Holst Section D Compartmentation in Cyclic Nucleotide Signaling Heart Failure, Fibrosis, and Cyclic Nucleotide Metabolism in Cardiac Fibroblasts, S. A. Epperson and L. L. Brunton Role of A-Kinase Anchoring Proteins in the Compartmentation in Cyclic Nucleotide Signaling, O. Witczak, E. M. Aandahl, and K. Tasken Role of Phosphodiesterases in Cyclic Nucleotide Compartmentation in Cardiac Myocytes, A. Abi-Gerges, L. R.V. Castro, F. Rochais, G. Vandecasteele, and R. Fischmeister Section E Phosphodiesterases as Pharmacological Targets in Disease Processes Role of PDEs in Vascular Health and Disease: Endothelial PDEs and Angiogenesis, T. Keravis, A. P. Silva, L. Favot, and C. Lugnier Regulation of PDE Expression in Arteries: Role in Controlling Vascular Cyclic Nucleotide Signaling, D. H. Maurice and D. G. Tilley Regulation and Function of Cyclic Nucleotide Phosphodiesterases in Vascular Smooth Muscle and Vascular Diseases, C. Yan, D. J. Nagel, and K. Jeon Role of Cyclic Nucleotide Phosphodiesterases in Heart Failure and Hypertension, M. A. Movsesian and C. J. Smith Molecular Determinants in Pulmonary Hypertension: The Role of PDE5, N.J. Pyne, F. Murray, R. Tate, and M.R. MacLean Role of PDE5 in Migraine, C. Kruuse Phosphodiesterase-4 as a Pharmacological Target Mediating Antidepressant and Cognitive Effects on Behavior, H. T. Zhang and J. M. O'Donnell Role of Phosphodiesterases in Apoptosis, A. Lerner, E. Y.Moon, and S. Tiwari Section F Development of Specific Phosphodiesterase Inhibitors as Therapeutic Agents Crystal Structure of Phosphodiesterase Families and the Potential for Rational Drug Design, K. Y. J. Zhang Structure, Catalytic Mechanism, and Inhibitor Selectivity of Cyclic Nucleotide Phosphodiesterases, H. Ke and H. Wang Bench to Bedside: Multiple Actions of the PDE3 Inhibitor Cilostazol, J. Kambayashi, Y. Shakur, and Y. Liu Reinventing the Wheel: Nonselective Phosphodiesterase Inhibitors for Chronic Inflammatory Diseases, M. A. Giembycz Medicinal Chemistry of PDE4 Inhibitors, J. M. McKenna and G. W. Muller Index
-
Regulation of Cyclic Nucleotide hydrolysis by cGMP
BMC Pharmacology, 2005Co-Authors: Joe BeavoAbstract:In this presentation I will discuss some of the physiological roles played by Cyclic Nucleotide phosphodiesterases that either hydrolyze cGMP or are regulated by cGMP. This will include potential new roles for PDE1B in the differentiation of monocytes into macrophages and dendritic cells. I will also discuss the concept that in many systems cAMP and cGMP act as physiological "brakes" on the function of the cells. Recently, it is becoming clear that one of the major reasons for having so many different Cyclic Nucleotide phosophodiesterases in the genome, is so that their expression can be individually regulated as a mechanism of releasing these "brakes" and thereby allowing the function to proceed. Examples that will be discussed include, regulation of fluid volume in the circulatory system, activation and function of T cells, proliferation of smooth muscle, and differentiation of monocytes. Finally, I will discuss some of the structural basis for the ability of cGMP to bind to and activate the Cyclic Nucleotide binding GAF domains on several different phosphodiesterases. from 2nd International Conference of cGMP Generators, Effectors and Therapeutic Implications Potsdam, Germany, 10–12 June, 2005
Henning Stahlberg - One of the best experts on this subject based on the ideXlab platform.
-
high resolution cryoelectron microscopy structure of the Cyclic Nucleotide modulated potassium channel mlok1 in a lipid bilayer
Structure, 2018Co-Authors: Julia Kowal, Crina M. Nimigean, Mohamed Chami, Paul Baumgartner, Nikhil Biyani, Sebastian Scherer, Andrzej J Rzepiela, Vikrant Upadhyay, Henning StahlbergAbstract:Eukaryotic Cyclic Nucleotide-modulated channels perform their diverse physiological roles by opening and closing their pores to ions in response to Cyclic Nucleotide binding. We here present a structural model for the Cyclic Nucleotide-modulated potassium channel homolog from Mesorhizobium loti, MloK1, determined from 2D crystals in the presence of lipids. Even though crystals diffract electrons to only ∼10 A, using cryoelectron microscopy (cryo-EM) and recently developed computational methods, we have determined a 3D map of full-length MloK1 in the presence of Cyclic AMP (cAMP) at ∼4.5 A isotropic 3D resolution. The structure provides a clear picture of the arrangement of the Cyclic Nucleotide-binding domains with respect to both the pore and the putative voltage sensor domains when cAMP is bound, and reveals a potential gating mechanism in the context of the lipid-embedded channel.
-
Real-time visualization of conformational changes within single MloK1 Cyclic Nucleotide-modulated channels.
Nature Communications, 2016Co-Authors: Martina Rangl, Atsushi Miyagi, Julia Kowal, Henning Stahlberg, Crina M. Nimigean, Simon ScheuringAbstract:Some ion channels are modulated by binding of Cyclic Nucleotide to a Cyclic Nucleotide-binding domain. Here, the authors use high-speed atomic force microscopy to directly monitor the conformational changes induced by ligand binding to a Cyclic Nucleotide-modulated channel from Mesorhizobium loti.
-
Ligand-induced structural changes in the Cyclic Nucleotide-modulated potassium channel MloK1.
Nature Communications, 2014Co-Authors: Julia Kowal, Martina Rangl, Crina M. Nimigean, Simon Scheuring, Mohamed Chami, Paul Baumgartner, Marcel Arheit, Po-lin Chiu, Gunnar Schroeder, Henning StahlbergAbstract:Cyclic Nucleotide-modulated ion channels are important for signal transduction and pacemaking in eukaryotes. The molecular determinants of ligand gating in these channels are still unknown, mainly because of a lack of direct structural information. Here we report ligand-induced conformational changes in full-length MloK1, a Cyclic Nucleotide-modulated potassium channel from the bacterium Mesorhizobium loti, analysed by electron crystallography and atomic force microscopy. Upon cAMP binding, the Cyclic Nucleotide-binding domains move vertically towards the membrane, and directly contact the S1-S4 voltage sensor domains. This is accompanied by a significant shift and tilt of the voltage sensor domain helices. In both states, the inner pore-lining helices are in an 'open' conformation. We propose a mechanism in which ligand binding can favour pore opening via a direct interaction between the Cyclic Nucleotide-binding domains and voltage sensors. This offers a simple mechanistic hypothesis for the coupling between ligand gating and voltage sensing in eukaryotic HCN channels.
Friedrich W. Herberg - One of the best experts on this subject based on the ideXlab platform.
-
Mutations of PKA Cyclic Nucleotide-binding domains reveal novel aspects of Cyclic Nucleotide selectivity.
The Biochemical journal, 2017Co-Authors: Robin Lorenz, Eui-whan Moon, Jeong Joo Kim, Sven H. Schmidt, Banumathi Sankaran, Ioannis V. Pavlidis, Choel Kim, Friedrich W. HerbergAbstract:Cyclic AMP and Cyclic GMP are ubiquitous second messengers that regulate the activity of effector proteins in all forms of life. The main effector proteins, the 3′,5′-Cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKA) and the 3′,5′-Cyclic guanosine monophosphate (cGMP)-dependent protein kinase (PKG), are preferentially activated by cAMP and cGMP, respectively. However, the molecular basis of this Cyclic Nucleotide selectivity is still not fully understood. Analysis of isolated Cyclic Nucleotide-binding (CNB) domains of PKA regulatory subunit type Iα (RIα) reveals that the C-terminal CNB-B has a higher cAMP affinity and selectivity than the N-terminal CNB-A. Here, we show that introducing cGMP-specific residues using site-directed mutagenesis reduces the selectivity of CNB-B, while the combination of two mutations (G316R/A336T) results in a cGMP-selective binding domain. Furthermore, introducing the corresponding mutations (T192R/A212T) into the PKA RIα CNB-A turns this domain into a highly cGMP-selective domain, underlining the importance of these contacts for achieving cGMP specificity. Binding data with the generic purine Nucleotide 3′,5′-Cyclic inosine monophosphate (cIMP) reveal that introduced arginine residues interact with the position 6 oxygen of the nucleobase. Co-crystal structures of an isolated CNB-B G316R/A336T double mutant with either cAMP or cGMP reveal that the introduced threonine and arginine residues maintain their conserved contacts as seen in PKG I CNB-B. These results improve our understanding of Cyclic Nucleotide binding and the molecular basis of Cyclic Nucleotide specificity.
-
Cyclic Nucleotide Mapping of Hyperpolarization-Activated Cyclic Nucleotide-Gated (HCN) Channels
ACS Chemical Biology, 2014Co-Authors: Stefan Möller, Anna Moroni, Andrea Alfieri, Daniela Bertinetti, Marco Aquila, Frank Schwede, Marco Lolicato, Holger Rehmann, Friedrich W. HerbergAbstract:Hyperpolarization-activated Cyclic Nucleotide-gated (HCN) channels play a central role in the regulation of cardiac and neuronal firing rate, and these channels can be dually activated by membrane hyperpolarization and by binding of Cyclic Nucleotides. cAMP has been shown to directly bind HCN channels and modulate their activity. Despite this, while there are selective inhibitors that block the activation potential of the HCN channels, regulation by cAMP analogs has not been well investigated. A comprehensive screen of 47 Cyclic Nucleotides with modifications in the nucleobase, ribose moiety, and Cyclic phosphate was tested on the three isoforms HCN1, HCN2, and HCN4. 7-CH-cAMP was identified to be a high affinity binder for HCN channels and crosschecked for its ability to act on other cAMP receptor proteins. While 7-CH-cAMP is a general activator for cAMP- and cGMP-dependent protein kinases as well as for the guanine Nucleotide exchange factors Epac1 and Epac2, it displays the highest affinity to HCN chan...
Crina M. Nimigean - One of the best experts on this subject based on the ideXlab platform.
-
high resolution cryoelectron microscopy structure of the Cyclic Nucleotide modulated potassium channel mlok1 in a lipid bilayer
Structure, 2018Co-Authors: Julia Kowal, Crina M. Nimigean, Mohamed Chami, Paul Baumgartner, Nikhil Biyani, Sebastian Scherer, Andrzej J Rzepiela, Vikrant Upadhyay, Henning StahlbergAbstract:Eukaryotic Cyclic Nucleotide-modulated channels perform their diverse physiological roles by opening and closing their pores to ions in response to Cyclic Nucleotide binding. We here present a structural model for the Cyclic Nucleotide-modulated potassium channel homolog from Mesorhizobium loti, MloK1, determined from 2D crystals in the presence of lipids. Even though crystals diffract electrons to only ∼10 A, using cryoelectron microscopy (cryo-EM) and recently developed computational methods, we have determined a 3D map of full-length MloK1 in the presence of Cyclic AMP (cAMP) at ∼4.5 A isotropic 3D resolution. The structure provides a clear picture of the arrangement of the Cyclic Nucleotide-binding domains with respect to both the pore and the putative voltage sensor domains when cAMP is bound, and reveals a potential gating mechanism in the context of the lipid-embedded channel.
-
Real-time visualization of conformational changes within single MloK1 Cyclic Nucleotide-modulated channels.
Nature Communications, 2016Co-Authors: Martina Rangl, Atsushi Miyagi, Julia Kowal, Henning Stahlberg, Crina M. Nimigean, Simon ScheuringAbstract:Some ion channels are modulated by binding of Cyclic Nucleotide to a Cyclic Nucleotide-binding domain. Here, the authors use high-speed atomic force microscopy to directly monitor the conformational changes induced by ligand binding to a Cyclic Nucleotide-modulated channel from Mesorhizobium loti.
-
Ligand-induced structural changes in the Cyclic Nucleotide-modulated potassium channel MloK1.
Nature Communications, 2014Co-Authors: Julia Kowal, Martina Rangl, Crina M. Nimigean, Simon Scheuring, Mohamed Chami, Paul Baumgartner, Marcel Arheit, Po-lin Chiu, Gunnar Schroeder, Henning StahlbergAbstract:Cyclic Nucleotide-modulated ion channels are important for signal transduction and pacemaking in eukaryotes. The molecular determinants of ligand gating in these channels are still unknown, mainly because of a lack of direct structural information. Here we report ligand-induced conformational changes in full-length MloK1, a Cyclic Nucleotide-modulated potassium channel from the bacterium Mesorhizobium loti, analysed by electron crystallography and atomic force microscopy. Upon cAMP binding, the Cyclic Nucleotide-binding domains move vertically towards the membrane, and directly contact the S1-S4 voltage sensor domains. This is accompanied by a significant shift and tilt of the voltage sensor domain helices. In both states, the inner pore-lining helices are in an 'open' conformation. We propose a mechanism in which ligand binding can favour pore opening via a direct interaction between the Cyclic Nucleotide-binding domains and voltage sensors. This offers a simple mechanistic hypothesis for the coupling between ligand gating and voltage sensing in eukaryotic HCN channels.
-
a Cyclic Nucleotide modulated prokaryotic k channel
The Journal of General Physiology, 2004Co-Authors: Crina M. Nimigean, Tania Shane, Christopher MillerAbstract:A search of prokaryotic genomes uncovered a gene from Mesorhizobium loti homologous to eukaryotic K+ channels of the S4 superfamily that also carry a Cyclic Nucleotide binding domain at the COOH terminus. The gene was cloned from genomic DNA, and the protein, denoted MloK1, was overexpressed in Escherichia coli and purified. Gel filtration analysis revealed a heterogeneous distribution of protein sizes which, upon inclusion of Cyclic Nucleotide, coalesces into a homogeneous population, eluting at the size expected for a homotetramer. As followed by a radioactive 86Rb+ flux assay, the putative channel protein catalyzes ionic flux with a selectivity expected for a K+ channel. Ion transport is stimulated by cAMP and cGMP at submicromolar concentrations. Since this bacterial homologue does not have the “C-linker” sequence found in all eukaryotic S4-type Cyclic Nucleotide-modulated ion channels, these results show that this four-helix structure is not a general requirement for transducing the Cyclic Nucleotide-binding signal to channel opening.
