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Abedi E, Kaveh S, Mohammad Bagher Hashemi S. Structure-based modification of a-amylase by conventional and emerging technologies: Comparative study on the secondary structure, activity, thermal stability and amylolysis efficiency. Food Chem 2024; 437:137903. [PMID: 37931423 DOI: 10.1016/j.foodchem.2023.137903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 10/22/2023] [Accepted: 10/27/2023] [Indexed: 11/08/2023]
Abstract
α-Amylase is an endo-enzyme that catalyzes the hydrolysis of starch into shorter oligosaccharides. α-Amylase plays a crucial role in various industries. Manipulated α-amylases are of particular interest due to their remarkable amylolysis efficiency and thermostability for large-scale biotechnological processes. The retained catalytic activity of enzymes is decreased according to extreme pH, temperature, pressure, and chemical reagents. Broad industrial applications of α-amylases need special properties such as stability against temperature, pH, and chelators, and also attain reusability, desirable enzymatic activity, efficiency, and selectivity. Considering the biotechnological importance of α-amylase, its high stability is the most critical challenge for its economic viability. Therefore, improving its functionality and stability recently gained much interest. To achieve this purpose, various emerging technologies in combination with conventional methods on α-Amylases with different sources have been conducted. The present review is an attempt to summarize the effect of various conventional methods and emerging technologies employed to date on α-amylase secondary structure, thermal stability, and performance.
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Affiliation(s)
- Elahe Abedi
- Department of Food Science and Technology, Faculty of Agriculture, Fasa University, Fasa, Iran
| | - Shima Kaveh
- Department of Food Science and Technology, Faculty of Agriculture, Fasa University, Fasa, Iran.
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Li D, Kirberger M, Qiao J, Gui Z, Xue S, Pu F, Jiang J, Xu Y, Tan S, Salarian M, Ibhagui O, Hekmatyar K, Yang JJ. Protein MRI Contrast Agents as an Effective Approach for Precision Molecular Imaging. Invest Radiol 2024; 59:170-186. [PMID: 38180819 DOI: 10.1097/rli.0000000000001057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2024]
Abstract
ABSTRACT Cancer and other acute and chronic diseases are results of perturbations of common molecular determinants in key biological and signaling processes. Imaging is critical for characterizing dynamic changes in tumors and metastases, the tumor microenvironment, tumor-stroma interactions, and drug targets, at multiscale levels. Magnetic resonance imaging (MRI) has emerged to be a primary imaging modality for both clinical and preclinical applications due to its advantages over other modalities, including sensitivity to soft tissues, nondepth limitations, and the use of nonionizing radiation. However, extending the application of MRI to achieve both qualitative and quantitative precise molecular imaging with the capability to quantify molecular biomarkers for early detection, staging, and monitoring therapeutic treatment requires the capacity to overcome several major challenges including the trade-off between metal-binding affinity and relaxivity, which is an issue frequently associated with small chelator contrast agents. In this review, we will introduce the criteria of ideal contrast agents for precision molecular imaging and discuss the relaxivity of current contrast agents with defined first shell coordination water molecules. We will then report our advances in creating a new class of protein-targeted MRI contrast agents (ProCAs) with contributions to relaxivity largely derived from the secondary sphere and correlation time. We will summarize our rationale, design strategy, and approaches to the development and optimization of our pioneering ProCAs with desired high relaxivity, metal stability, and molecular biomarker-targeting capability, for precision MRI. From first generation (ProCA1) to third generation (ProCA32), we have achieved dual high r1 and r2 values that are 6- to 10-fold higher than clinically approved contrast agents at magnetic fields of 1.5 T, and their relaxivity values at high field are also significantly higher, which enables high resolution during small animal imaging. Further engineering of multiple targeting moieties enables ProCA32 agents that have strong biomarker-binding affinity and specificity for an array of key molecular biomarkers associated with various chronic diseases, while maintaining relaxation and exceptional metal-binding and selectivity, serum stability, and resistance to transmetallation, which are critical in mitigating risks associated with metal toxicity. Our leading product ProCA32.collagen has enabled the first early detection of liver metastasis from multiple cancers at early stages by mapping the tumor environment and early stage of fibrosis from liver and lung in vivo, with strong translational potential to extend to precision MRI for preclinical and clinical applications for precision diagnosis and treatment.
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Affiliation(s)
- Dongjun Li
- From the Center for Diagnostics and Therapeutics, Advanced Translational Imaging Facility, Department of Chemistry, Georgia State University, Atlanta, GA (D.L., M.K., J.Q., Z.G., S.X., P.F., J.J., S.T., M.S., O.I., K.H., J.J.Y.); and InLighta BioSciences, LLC, Marietta, GA (Y.X., J.J.Y)
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Bhar A, Chakraborty A, Roy A. The captivating role of calcium in plant-microbe interaction. FRONTIERS IN PLANT SCIENCE 2023; 14:1138252. [PMID: 36938033 PMCID: PMC10020633 DOI: 10.3389/fpls.2023.1138252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 02/16/2023] [Indexed: 06/18/2023]
Abstract
Plant immune response is fascinating due to the complete absence of a humoral system. The adaptive immune response in plants relies on the intracellular orchestration of signalling molecules or intermediates associated with transcriptional reprogramming. Plant disease response phenomena largely depend on pathogen recognition, signal perception, and intracellular signal transduction. The pathogens possess specific pathogen-associated molecular patterns (PAMP) or microbe-associated molecular patterns (MAMP), which are first identified by pattern recognition receptors (PRRs) of host plants for successful infection. After successful pathogen recognition, the defence response is initiated within plants. The first line of non-specific defence response is called PAMP-triggered immunity (PTI), followed by the specific robust signalling is called effector-triggered immunity (ETI). Calcium plays a crucial role in both PTI and ETI. The biphasic induction of reactive oxygen species (ROS) is inevitable in any plant-microbe interaction. Calcium ions play crucial roles in the initial oxidative burst and ROS induction. Different pathogens can induce calcium accumulation in the cytosol ([Ca2+]Cyt), called calcium signatures. These calcium signatures further control the diverse defence-responsive proteins in the intracellular milieu. These calcium signatures then activate calcium-dependent protein kinases (CDPKs), calcium calmodulins (CaMs), calcineurin B-like proteins (CBLs), etc., to impart intricate defence signalling within the cell. Decoding this calcium ionic map is imperative to unveil any plant microbe interplay and modulate defence-responsive pathways. Hence, the present review is unique in developing concepts of calcium signature in plants and their subsequent decoding mechanism. This review also intends to articulate early sensing of calcium oscillation, signalling events, and comprehensive mechanistic roles of calcium within plants during pathogenic ingression. This will accumulate and summarize the exciting roles of calcium ions in plant immunity and provide the foundation for future research.
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Affiliation(s)
- Anirban Bhar
- Post Graduate Department of Botany, Ramakrishna Mission Vivekananda Centenary College, Kolkata, India
| | - Amrita Chakraborty
- Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Prague, Czech Republic
| | - Amit Roy
- Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Prague, Czech Republic
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Abstract
Natural metalloproteins perform many functions - ranging from sensing to electron transfer and catalysis - in which the position and property of each ligand and metal, is dictated by protein structure. De novo protein design aims to define an amino acid sequence that encodes a specific structure and function, providing a critical test of the hypothetical inner workings of (metallo)proteins. To date, de novo metalloproteins have used simple, symmetric tertiary structures - uncomplicated by the large size and evolutionary marks of natural proteins - to interrogate structure-function hypotheses. In this Review, we discuss de novo design applications, such as proteins that induce complex, increasingly asymmetric ligand geometries to achieve function, as well as the use of more canonical ligand geometries to achieve stability. De novo design has been used to explore how proteins fine-tune redox potentials and catalyse both oxidative and hydrolytic reactions. With an increased understanding of structure-function relationships, functional proteins including O2-dependent oxidases, fast hydrolases, and multi-proton/multi-electron reductases, have been created. In addition, proteins can now be designed using xeno-biological metals or cofactors and principles from inorganic chemistry to derive new-to-nature functions. These results and the advances in computational protein design suggest a bright future for the de novo design of diverse, functional metalloproteins.
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Affiliation(s)
- Matthew J. Chalkley
- Department of Pharmaceutical Chemistry and the Cardiovascular Research Institute, University of California at San Francisco, San Francisco, (CA), USA
| | - Samuel I. Mann
- Department of Pharmaceutical Chemistry and the Cardiovascular Research Institute, University of California at San Francisco, San Francisco, (CA), USA
| | - William F. DeGrado
- Department of Pharmaceutical Chemistry and the Cardiovascular Research Institute, University of California at San Francisco, San Francisco, (CA), USA
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Wenzhong L, Hualan L. COVID-19: the CaMKII-like system of S protein drives membrane fusion and induces syncytial multinucleated giant cells. Immunol Res 2021; 69:496-519. [PMID: 34410575 PMCID: PMC8374125 DOI: 10.1007/s12026-021-09224-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 07/24/2021] [Indexed: 02/07/2023]
Abstract
The SARS-CoV-2 S protein on the membrane of infected cells can promote receptor-dependent syncytia formation, relating to extensive tissue damage and lymphocyte elimination. In this case, it is challenging to obtain neutralizing antibodies and prevent them through antibodies effectively. Considering that, in the current study, structural domain search methods are adopted to analyze the SARS-CoV-2 S protein to find the fusion mechanism. The results show that after the EF-hand domain of S protein bound to calcium ions, S2 protein had CaMKII protein activities. Besides, the CaMKII_AD domain of S2 changed S2 conformation, facilitating the formation of HR1-HR2 six-helix bundles. Apart from that, the Ca2+-ATPase of S2 pumped calcium ions from the virus cytoplasm to help membrane fusion, while motor structures of S drove the CaATP_NAI and CaMKII_AD domains to extend to the outside and combined the viral membrane and the cell membrane, thus forming a calcium bridge. Furthermore, the phospholipid-flipping-ATPase released water, triggering lipid mixing and fusion and generating fusion pores. Then, motor structures promoted fusion pore extension, followed by the cytoplasmic contents of the virus being discharged into the cell cytoplasm. After that, the membrane of the virus slid onto the cell membrane along the flowing membrane on the gap of the three CaATP_NAI. At last, the HR1-HR2 hexamer would fall into the cytoplasm or stay on the cell membrane. Therefore, the CaMKII_like system of S protein facilitated membrane fusion for further inducing syncytial multinucleated giant cells.
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Affiliation(s)
- Liu Wenzhong
- School of Computer Science and Engineering, Sichuan University of Science & Engineering, Zigong, 643002, China.
- School of Life Science and Food Engineering, Yibin University, Yibin, 644000, China.
| | - Li Hualan
- School of Life Science and Food Engineering, Yibin University, Yibin, 644000, China
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Pourfarjam Y, Ma Z, Kurinov I, Moss J, Kim IK. Structural and biochemical analysis of human ADP-ribosyl-acceptor hydrolase 3 reveals the basis of metal selectivity and different roles for the two magnesium ions. J Biol Chem 2021; 296:100692. [PMID: 33894202 PMCID: PMC8141533 DOI: 10.1016/j.jbc.2021.100692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 04/12/2021] [Accepted: 04/20/2021] [Indexed: 11/18/2022] Open
Abstract
ADP-ribosylation is a reversible and site-specific post-translational modification that regulates a wide array of cellular signaling pathways. Regulation of ADP-ribosylation is vital for maintaining genomic integrity, and uncontrolled accumulation of poly(ADP-ribosyl)ation triggers a poly(ADP-ribose) (PAR)–dependent release of apoptosis-inducing factor from mitochondria, leading to cell death. ADP-ribosyl-acceptor hydrolase 3 (ARH3) cleaves PAR and mono(ADP-ribosyl)ation at serine following DNA damage. ARH3 is also a metalloenzyme with strong metal selectivity. While coordination of two magnesium ions (MgA and MgB) significantly enhances its catalytic efficiency, calcium binding suppresses its function. However, how the coordination of different metal ions affects its catalysis has not been defined. Here, we report a new crystal structure of ARH3 complexed with its product ADP-ribose and calcium. This structure shows that calcium coordination significantly distorts the binuclear metal center of ARH3, which results in decreased binding affinity to ADP-ribose, and suboptimal substrate alignment, leading to impaired hydrolysis of PAR and mono(ADP-ribosyl)ated serines. Furthermore, combined structural and mutational analysis of the metal-coordinating acidic residues revealed that MgA is crucial for optimal substrate positioning for catalysis, whereas MgB plays a key role in substrate binding. Our collective data provide novel insights into the different roles of these metal ions and the basis of metal selectivity of ARH3 and contribute to understanding the dynamic regulation of cellular ADP-ribosylations during the DNA damage response.
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Affiliation(s)
- Yasin Pourfarjam
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio, USA
| | - Zhijun Ma
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio, USA
| | - Igor Kurinov
- Department of Chemistry and Chemical Biology, NE-CAT APS, Cornell University, Argonne, Illinois, USA
| | - Joel Moss
- Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - In-Kwon Kim
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio, USA.
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Zhang P, Han J, Cieplak P, Cheung MS. Determining the atomic charge of calcium ion requires the information of its coordination geometry in an EF-hand motif. J Chem Phys 2021; 154:124104. [PMID: 33810667 DOI: 10.1063/5.0037517] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
It is challenging to parameterize the force field for calcium ions (Ca2+) in calcium-binding proteins because of their unique coordination chemistry that involves the surrounding atoms required for stability. In this work, we observed a wide variation in Ca2+ binding loop conformations of the Ca2+-binding protein calmodulin, which adopts the most populated ternary structures determined from the molecular dynamics simulations, followed by ab initio quantum mechanical (QM) calculations on all 12 amino acids in the loop that coordinate Ca2+ in aqueous solution. Ca2+ charges were derived by fitting to the electrostatic potential in the context of a classical or polarizable force field (PFF). We discovered that the atomic radius of Ca2+ in conventional force fields is too large for the QM calculation to capture the variation in the coordination geometry of Ca2+ in its ionic form, leading to unphysical charges. Specifically, we found that the fitted atomic charges of Ca2+ in the context of PFF depend on the coordinating geometry of electronegative atoms from the amino acids in the loop. Although nearby water molecules do not influence the atomic charge of Ca2+, they are crucial for compensating for the coordination of Ca2+ due to the conformational flexibility in the EF-hand loop. Our method advances the development of force fields for metal ions and protein binding sites in dynamic environments.
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Affiliation(s)
- Pengzhi Zhang
- Department of Physics, University of Houston, Houston, Texas 77204, USA
| | - Jaebeom Han
- Department of Physics, University of Houston, Houston, Texas 77204, USA
| | - Piotr Cieplak
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California 92037, USA
| | - Margaret S Cheung
- Department of Physics, University of Houston, Houston, Texas 77204, USA
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Allert MJ, Hellinga HW. Harnessing Environmental Ca 2+ for Extracellular Protein Thermostabilization. Biochemistry 2020; 59:3725-3740. [PMID: 32915552 DOI: 10.1021/acs.biochem.0c00449] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Ca2+ is the third-most prevalent metal ion in the environment. EF hands are common Ca2+-binding motifs found in both extracellular and intracellular proteins of eukaryotes and prokaryotes. Cytoplasmic EF hand proteins often mediate allosteric control of signal transduction pathway components in response to intracellular Ca2+ concentration fluctuations by coupling Ca2+ binding to changes in protein structure. We show that an extracellular structural Ca2+-binding site mediates protein thermostabilization by such conformational coupling as well. Binding Ca2+ to the EF hand of the extracellular (periplasmic) Escherichia coli glucose-galactose binding protein thermostabilizes this protein by ∼17 K relative to its Ca2+-free form. Using statistical thermodynamic analysis of a fluorescent conjugate of ecGGBP that reports simultaneously on ligand binding and multiple conformational states, we found that its Ca2+-mediated stabilization is determined by conformational coupling mechanisms in two independent conformational exchange reactions. Binding to folded and unfolded states determines the maximum Ca2+-mediated stability. A disorder → order transition accompanies the formation of the Ca2+ complex in the folded state and dictates the minimum Ca2+ concentration at which the Ca2+-bound state becomes dominant. Similar transitions also encode the structural changes necessary for Ca2+-mediated control elements in signal transduction pathways. Ca2+-mediated thermostabilization and allosteric control, therefore, share a fundamental conformational coupling mechanism, which may have implications for the evolution of EF hands.
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Affiliation(s)
- Malin J Allert
- Department of Biochemistry, Duke University Medical Center, P.O. Box 3711, Durham, North Carolina 27710, United States
| | - Homme W Hellinga
- Department of Biochemistry, Duke University Medical Center, P.O. Box 3711, Durham, North Carolina 27710, United States
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9
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Law ML, Cohen H, Martin AA, Angulski ABB, Metzger JM. Dysregulation of Calcium Handling in Duchenne Muscular Dystrophy-Associated Dilated Cardiomyopathy: Mechanisms and Experimental Therapeutic Strategies. J Clin Med 2020; 9:jcm9020520. [PMID: 32075145 PMCID: PMC7074327 DOI: 10.3390/jcm9020520] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 02/06/2020] [Indexed: 02/07/2023] Open
Abstract
: Duchenne muscular dystrophy (DMD) is an X-linked recessive disease resulting in the loss of dystrophin, a key cytoskeletal protein in the dystrophin-glycoprotein complex. Dystrophin connects the extracellular matrix with the cytoskeleton and stabilizes the sarcolemma. Cardiomyopathy is prominent in adolescents and young adults with DMD, manifesting as dilated cardiomyopathy (DCM) in the later stages of disease. Sarcolemmal instability, leading to calcium mishandling and overload in the cardiac myocyte, is a key mechanistic contributor to muscle cell death, fibrosis, and diminished cardiac contractile function in DMD patients. Current therapies for DMD cardiomyopathy can slow disease progression, but they do not directly target aberrant calcium handling and calcium overload. Experimental therapeutic targets that address calcium mishandling and overload include membrane stabilization, inhibition of stretch-activated channels, ryanodine receptor stabilization, and augmentation of calcium cycling via modulation of the Serca2a/phospholamban (PLN) complex or cytosolic calcium buffering. This paper addresses what is known about the mechanistic basis of calcium mishandling in DCM, with a focus on DMD cardiomyopathy. Additionally, we discuss currently utilized therapies for DMD cardiomyopathy, and review experimental therapeutic strategies targeting the calcium handling defects in DCM and DMD cardiomyopathy.
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Affiliation(s)
- Michelle L. Law
- Department of Family and Consumer Sciences, Robbins College of Health and Human Sciences, Baylor University, Waco, TX 76706, USA;
| | - Houda Cohen
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, MN 55455, USA; (H.C.); (A.A.M.); (A.B.B.A.)
| | - Ashley A. Martin
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, MN 55455, USA; (H.C.); (A.A.M.); (A.B.B.A.)
| | - Addeli Bez Batti Angulski
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, MN 55455, USA; (H.C.); (A.A.M.); (A.B.B.A.)
| | - Joseph M. Metzger
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, MN 55455, USA; (H.C.); (A.A.M.); (A.B.B.A.)
- Correspondence: ; Tel.: +1-612-625-5902; Fax: +1-612-625-5149
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10
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Harsini FM, Bui AA, Rice AM, Chebrolu S, Fuson KL, Turtoi A, Bradberry M, Chapman ER, Sutton RB. Structural Basis for the Distinct Membrane Binding Activity of the Homologous C2A Domains of Myoferlin and Dysferlin. J Mol Biol 2019; 431:2112-2126. [PMID: 31004665 DOI: 10.1016/j.jmb.2019.04.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2019] [Revised: 04/04/2019] [Accepted: 04/04/2019] [Indexed: 02/03/2023]
Abstract
Dysferlin has been implicated in acute membrane repair processes, whereas myoferlin's activity is maximal during the myoblast fusion stage of early skeletal muscle cell development. Both proteins are similar in size and domain structure; however, despite the overall similarity, myoferlin's known physiological functions do not overlap with those of dysferlin. Here we present for the first time the X-ray crystal structure of human myoferlin C2A to 1.9 Å resolution bound to two divalent cations, and compare its three-dimensional structure and membrane binding activities to that of dysferlin C2A. We find that while dysferlin C2A binds membranes in a Ca2+-dependent manner, Ca2+ binding was the rate-limiting kinetic step for this interaction. Myoferlin C2A, on the other hand, binds two calcium ions with an affinity 3-fold lower than that of dysferlin C2A; and, surprisingly, myoferlin C2A binds only marginally to phospholipid mixtures with a high fraction of phosphatidylserine.
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Affiliation(s)
- Faraz M Harsini
- Department of Cell Physiology and Molecular Biophysics, Texas Tech University Health Sciences Center, Lubbock, TX, 79430, USA; Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX, 79430, USA
| | - Anthony A Bui
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX, 79409, USA
| | - Anne M Rice
- Department of Biophysics, Johns Hopkins University, Baltimore, MD, 21205, USA
| | - Sukanya Chebrolu
- Department of Cell Physiology and Molecular Biophysics, Texas Tech University Health Sciences Center, Lubbock, TX, 79430, USA
| | - Kerry L Fuson
- Department of Cell Physiology and Molecular Biophysics, Texas Tech University Health Sciences Center, Lubbock, TX, 79430, USA
| | - Andrei Turtoi
- Tumor Microenvironment and Resistance to Treatment Lab, Institut de Recherche en Cancrologie de Montpellier, 34090 Montpellier, France; Institut du Cancer Montpellier, 34090 Montpellier, France; Universit Montpellier, 34298 Montpellier, France
| | - Mazdak Bradberry
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Edwin R Chapman
- Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, WI, 53705, USA; Department of Neuroscience, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - R Bryan Sutton
- Department of Cell Physiology and Molecular Biophysics, Texas Tech University Health Sciences Center, Lubbock, TX, 79430, USA; Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX, 79430, USA.
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11
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Zhao Y, Guo X, Yang B. Calcium-induced human centrin 1 self-assembly and double-regulating the binding with peptide R18-Sfi1p. Int J Biol Macromol 2019; 128:314-323. [PMID: 30682474 DOI: 10.1016/j.ijbiomac.2019.01.096] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 01/02/2019] [Accepted: 01/19/2019] [Indexed: 10/27/2022]
Abstract
Centrin is a member of the EF-hand super-family that plays pivotal role in the centrosome duplication and separation. In the present paper, we characterized the properties of metal ions as well as peptide R18-Sfi1p binding to human centrin 1 (HsCen1) by fluorescence spectra and isothermal titration calorimetry (ITC). Four metal ions binding sites on HsCen1 were identified through ITC experiments. The conditional binding constants of the EF-hand domain on HsCen1 with Ca2+ were quantitatively calculated. In reversible manner, Ca2+ can induce HsCen1 self-assembly. In addition, HsCen1 bound with peptide R18-Sfi1p in calcium-dependent with middle-affinity. Phosphorylation at Ser170 weakened interaction HsCen1 with the substrate and removal calcium ions further weakened interactions of the two molecules. Hence, we inferred that centrin initiating downstream peptides may be a double-regulated process by calcium and phosphorylation. These results are of significance for understanding the relationship between PTM and metal regulation.
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Affiliation(s)
- Yaqin Zhao
- Institute of Molecular Science, Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Shanxi University, Taiyuan 030006, China
| | - Xiaojuan Guo
- Institute of Molecular Science, Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Shanxi University, Taiyuan 030006, China
| | - Binsheng Yang
- Institute of Molecular Science, Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Shanxi University, Taiyuan 030006, China.
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12
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Dudev T, Grauffel C, Lim C. How Pb2+ Binds and Modulates Properties of Ca2+-Signaling Proteins. Inorg Chem 2018; 57:14798-14809. [DOI: 10.1021/acs.inorgchem.8b02548] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Todor Dudev
- Faculty of Chemistry and Pharmacy, Sofia University, Sofia 1164, Bulgaria
| | - Cédric Grauffel
- Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan
| | - Carmay Lim
- Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan
- Department of Chemistry, National Tsing Hua University, Hsinchu 300, Taiwan
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13
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Mazmanian K, Dudev T, Lim C. How First Shell–Second Shell Interactions and Metal Substitution Modulate Protein Function. Inorg Chem 2018; 57:14052-14061. [DOI: 10.1021/acs.inorgchem.8b01029] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Karine Mazmanian
- Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan
- Chemical Biology and Molecular Biophysics Program, Taiwan International Graduate Program, Academia Sinica, Taipei 10617, Taiwan
- Taiwan and Institute of Biochemical Sciences, National Taiwan University, Taipei 10617, Taiwan
| | - Todor Dudev
- Faculty of Chemistry and Pharmacy, Sofia University, Sofia 1164, Bulgaria
| | - Carmay Lim
- Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan
- Department of Chemistry, National Tsing Hua University, Hsinchu 300, Taiwan
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14
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La Verde V, Dominici P, Astegno A. Towards Understanding Plant Calcium Signaling through Calmodulin-Like Proteins: A Biochemical and Structural Perspective. Int J Mol Sci 2018; 19:E1331. [PMID: 29710867 PMCID: PMC5983762 DOI: 10.3390/ijms19051331] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 04/26/2018] [Accepted: 04/26/2018] [Indexed: 11/17/2022] Open
Abstract
Ca2+ ions play a key role in a wide variety of environmental responses and developmental processes in plants, and several protein families with Ca2+-binding domains have evolved to meet these needs, including calmodulin (CaM) and calmodulin-like proteins (CMLs). These proteins have no catalytic activity, but rather act as sensor relays that regulate downstream targets. While CaM is well-studied, CMLs remain poorly characterized at both the structural and functional levels, even if they are the largest class of Ca2+ sensors in plants. The major structural theme in CMLs consists of EF-hands, and variations in these domains are predicted to significantly contribute to the functional versatility of CMLs. Herein, we focus on recent advances in understanding the features of CMLs from biochemical and structural points of view. The analysis of the metal binding and structural properties of CMLs can provide valuable insight into how such a vast array of CML proteins can coexist, with no apparent functional redundancy, and how these proteins contribute to cellular signaling while maintaining properties that are distinct from CaM and other Ca2+ sensors. An overview of the principal techniques used to study the biochemical properties of these interesting Ca2+ sensors is also presented.
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Affiliation(s)
- Valentina La Verde
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona, Italy.
| | - Paola Dominici
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona, Italy.
| | - Alessandra Astegno
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona, Italy.
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15
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Coordination to lanthanide ions distorts binding site conformation in calmodulin. Proc Natl Acad Sci U S A 2018; 115:E3126-E3134. [PMID: 29545272 DOI: 10.1073/pnas.1722042115] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The Ca2+-sensing protein calmodulin (CaM) is a popular model of biological ion binding since it is both experimentally tractable and essential to survival in all eukaryotic cells. CaM modulates hundreds of target proteins and is sensitive to complex patterns of Ca2+ exposure, indicating that it functions as a sophisticated dynamic transducer rather than a simple on/off switch. Many details of this transduction function are not well understood. Fourier transform infrared (FTIR) spectroscopy, ultrafast 2D infrared (2D IR) spectroscopy, and electronic structure calculations were used to probe interactions between bound metal ions (Ca2+ and several trivalent lanthanide ions) and the carboxylate groups in CaM's EF-hand ion-coordinating sites. Since Tb3+ is commonly used as a luminescent Ca2+ analog in studies of protein-ion binding, it is important to characterize distinctions between the coordination of Ca2+ and the lanthanides in CaM. Although functional assays indicate that Tb3+ fully activates many Ca2+-dependent proteins, our FTIR spectra indicate that Tb3+, La3+, and Lu3+ disrupt the bidentate coordination geometry characteristic of the CaM binding sites' strongly conserved position 12 glutamate residue. The 2D IR spectra indicate that, relative to the Ca2+-bound form, lanthanide-bound CaM exhibits greater conformational flexibility and larger structural fluctuations within its binding sites. Time-dependent 2D IR lineshapes indicate that binding sites in Ca2+-CaM occupy well-defined configurations, whereas binding sites in lanthanide-bound-CaM are more disordered. Overall, the results show that binding to lanthanide ions significantly alters the conformation and dynamics of CaM's binding sites.
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16
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Narayanasamy S, Aradhyam GK. The Differential Response to Ca 2+ from Vertebrate and Invertebrate Calumenin Is Governed by a Single Amino Acid Residue. Biochemistry 2018; 57:722-731. [PMID: 29319298 DOI: 10.1021/acs.biochem.7b00762] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Calumenin (Calu) is a well-conserved multi-EF-hand-containing Ca2+-binding protein. In this work, we focused on the alterations that calumenin has undergone during evolution. We demonstrate that vertebrate calumenin is significantly different from its invertebrate homologues with respect to its response to Ca2+ binding. Human calumenin (HsCalu1) is intrinsically unstructured in the Ca2+ free form and responds to Ca2+ with a dramatic gain in structure. Calumenin from Caenorhabditis elegans (CeCalu) is structured even in the apo form, with no conformational change upon binding of Ca2+. We decode this structural and functional distinction by identifying a single "Leu" residue-based switch located in the fourth EF-hand of HsCalu1, occupied by "Gly" in the invertebrate homologues. We demonstrate that replacing Leu with Gly (L150G) in HsCalu1 enables the protein to adopt a structural fold even in the Ca2+ free form, similar to CeCalu, leading to ligand compensation (adoption of structure in the absence of Ca2+). The fourth (of seven) EF-hand of HsCalu1 nucleates the structural fold of the protein depending on the switch residue (Gly or Leu). Our analyses reveal that the Leu that replaced Gly from fishes onward is absolutely conserved in higher vertebrates, while lower organisms have Gly, not only enlarging the scope of Ca2+-dependent structural transitions but also drawing a boundary between the invertebrate and vertebrate calumenin. The evolutionary selection of the switch residue strongly corroborates the change in the structure of the protein and its pleiotropic functions and seems like it can be extended to the presence or absence of a heart in that organism.
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Affiliation(s)
- Sasirekha Narayanasamy
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras , Chennai 600036, India
| | - Gopala Krishna Aradhyam
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras , Chennai 600036, India
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17
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Crystal structure of a Ca 2+-dependent regulator of flagellar motility reveals the open-closed structural transition. Sci Rep 2018; 8:2014. [PMID: 29386625 PMCID: PMC5792641 DOI: 10.1038/s41598-018-19898-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 01/10/2018] [Indexed: 12/28/2022] Open
Abstract
Sperm chemotaxis toward a chemoattractant is very important for the success of fertilization. Calaxin, a member of the neuronal calcium sensor protein family, directly acts on outer-arm dynein and regulates specific flagellar movement during sperm chemotaxis of ascidian, Ciona intestinalis. Here, we present the crystal structures of calaxin both in the open and closed states upon Ca2+ and Mg2+ binding. The crystal structures revealed that three of the four EF-hands of a calaxin molecule bound Ca2+ ions and that EF2 and EF3 played a critical role in the conformational transition between the open and closed states. The rotation of α7 and α8 helices induces a significant conformational change of a part of the α10 helix into the loop. The structural differences between the Ca2+- and Mg2+-bound forms indicates that EF3 in the closed state has a lower affinity for Mg2+, suggesting that calaxin tends to adopt the open state in Mg2+-bound form. SAXS data supports that Ca2+-binding causes the structural transition toward the closed state. The changes in the structural transition of the C-terminal domain may be required to bind outer-arm dynein. These results provide a novel mechanism for recognizing a target protein using a calcium sensor protein.
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18
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Revisiting paradigms of Ca2+ signaling protein kinase regulation in plants. Biochem J 2018; 475:207-223. [DOI: 10.1042/bcj20170022] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 12/07/2017] [Accepted: 12/08/2017] [Indexed: 12/15/2022]
Abstract
Calcium (Ca2+) serves as a universal second messenger in eukaryotic signal transduction. Understanding the Ca2+ activation kinetics of Ca2+ sensors is critical to understanding the cellular signaling mechanisms involved. In this review, we discuss the regulatory properties of two sensor classes: the Ca2+-dependent protein kinases (CPKs/CDPKs) and the calcineurin B-like (CBL) proteins that control the activity of CBL-interacting protein kinases (CIPKs) and identify emerging topics and some foundational points that are not well established experimentally. Most plant CPKs are activated by physiologically relevant Ca2+ concentrations except for those with degenerate EF hands, and new results suggest that the Ca2+-dependence of kinase activation may be modulated by both protein–protein interactions and CPK autophosphorylation. Early results indicated that activation of plant CPKs by Ca2+ occurred by relief of autoinhibition. However, recent studies of protist CDPKs suggest that intramolecular interactions between CDPK domains contribute allosteric control to CDPK activation. Further studies are required to elucidate the mechanisms regulating plant CPKs. With CBL–CIPKs, the two major activation mechanisms are thought to be (i) binding of Ca2+-bound CBL to the CIPK and (ii) phosphorylation of residues in the CIPK activation loop. However, the relative importance of these two mechanisms in regulating CIPK activity is unclear. Furthermore, information detailing activation by physiologically relevant [Ca2+] is lacking, such that the paradigm of CBLs as Ca2+ sensors still requires critical, experimental validation. Developing models of CPK and CIPK regulation is essential to understand how these kinases mediate Ca2+ signaling and to the design of experiments to test function in vivo.
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19
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Ogunrinde A, Munro K, Davidson A, Ubaid M, Snedden WA. Arabidopsis Calmodulin-Like Proteins, CML15 and CML16 Possess Biochemical Properties Distinct from Calmodulin and Show Non-overlapping Tissue Expression Patterns. FRONTIERS IN PLANT SCIENCE 2017; 8:2175. [PMID: 29312414 PMCID: PMC5743801 DOI: 10.3389/fpls.2017.02175] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 12/12/2017] [Indexed: 05/20/2023]
Abstract
Calcium ions are used as ubiquitous, key second messengers in cells across eukaryotic taxa. In plants, calcium signal transduction is involved in a wide range of cellular processes from abiotic and biotic stress responses to development and growth. Calcium signals are detected by calcium sensor proteins, of which calmodulin (CaM), is the most evolutionarily conserved and well-studied. These sensors regulate downstream targets to propagate the information in signaling pathways. Plants possess a large family of calcium sensors related to CaM, termed CaM-like (CMLs), that are not found in animals and remain largely unstudied at the structural and functional level. Here, we investigated the biochemical properties and gene promoter activity of two closely related members of the Arabidopsis CML family, CML15 and CML16. Biochemical characterization of recombinant CML15 and CML16 indicated that they possess properties consistent with their predicted roles as calcium sensors. In the absence of calcium, CML15 and CML16 display greater intrinsic hydrophobicity than CaM. Both CMLs displayed calcium-dependent and magnesium-independent conformational changes that expose hydrophobic residues, but the degree of hydrophobic exposure was markedly less than that observed for CaM. Isothermal titration calorimetry indicated two and three calcium-binding sites for CML15 and CML16, respectively, with affinities expected to be within a physiological range. Both CML15 and CML16 bound calcium with high affinity in the presence of excess magnesium. Promoter-reporter analysis demonstrated that the CML16 promoter is active across a range of Arabidopsis tissues and developmental stages, whereas the CML15 promoter activity is very restricted and was observed only in floral tissues, specifically anthers and pollen. Collectively, our data indicate that these CMLs behave biochemically like calcium sensors but with properties distinct from CaM and likely have non-overlapping roles in floral development. We discuss our findings in the broader context of calcium sensors and signaling in Arabidopsis.
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Affiliation(s)
| | - Kim Munro
- Protein Function Discovery Laboratory, Department of Biomedical and Medical Sciences, Queen's University, Kingston, ON, Canada
| | | | - Midhat Ubaid
- Department of Biology, Queen's University, Kingston, ON, Canada
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20
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Abstract
Cardiac contractility is regulated by changes in intracellular Ca concentration ([Ca2+]i). Normal function requires that [Ca2+]i be sufficiently high in systole and low in diastole. Much of the Ca needed for contraction comes from the sarcoplasmic reticulum and is released by the process of calcium-induced calcium release. The factors that regulate and fine-tune the initiation and termination of release are reviewed. The precise control of intracellular Ca cycling depends on the relationships between the various channels and pumps that are involved. We consider 2 aspects: (1) structural coupling: the transporters are organized within the dyad, linking the transverse tubule and sarcoplasmic reticulum and ensuring close proximity of Ca entry to sites of release. (2) Functional coupling: where the fluxes across all membranes must be balanced such that, in the steady state, Ca influx equals Ca efflux on every beat. The remainder of the review considers specific aspects of Ca signaling, including the role of Ca buffers, mitochondria, Ca leak, and regulation of diastolic [Ca2+]i.
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Affiliation(s)
- David A Eisner
- From the Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Manchester Academic Health Sciences Centre, University of Manchester, United Kingdom.
| | - Jessica L Caldwell
- From the Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Manchester Academic Health Sciences Centre, University of Manchester, United Kingdom
| | - Kornél Kistamás
- From the Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Manchester Academic Health Sciences Centre, University of Manchester, United Kingdom
| | - Andrew W Trafford
- From the Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Manchester Academic Health Sciences Centre, University of Manchester, United Kingdom
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21
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Molecular Basis for Modulation of Metabotropic Glutamate Receptors and Their Drug Actions by Extracellular Ca 2. Int J Mol Sci 2017; 18:ijms18030672. [PMID: 28335551 PMCID: PMC5372683 DOI: 10.3390/ijms18030672] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 03/13/2017] [Accepted: 03/17/2017] [Indexed: 12/24/2022] Open
Abstract
Metabotropic glutamate receptors (mGluRs) associated with the slow phase of the glutamatergic signaling pathway in neurons of the central nervous system have gained importance as drug targets for chronic neurodegenerative diseases. While extracellular Ca2+ was reported to exhibit direct activation and modulation via an allosteric site, the identification of those binding sites was challenged by weak binding. Herein, we review the discovery of extracellular Ca2+ in regulation of mGluRs, summarize the recent developments in probing Ca2+ binding and its co-regulation of the receptor based on structural and biochemical analysis, and discuss the molecular basis for Ca2+ to regulate various classes of drug action as well as its importance as an allosteric modulator in mGluRs.
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22
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Koepf M, Bergkamp JJ, Teillout AL, Llansola-Portoles MJ, Kodis G, Moore AL, Gust D, Moore TA. Design of porphyrin-based ligands for the assembly of [d-block metal : calcium] bimetallic centers. Dalton Trans 2017; 46:4199-4208. [DOI: 10.1039/c6dt04647a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A secondary binding-site for alkaline-earth cations is introduced on a porphyrin platform to obtain competent bitopicN,O-ligands.
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Affiliation(s)
- Matthieu Koepf
- School of Molecular Sciences
- Arizona State University
- Tempe
- USA
| | | | | | | | - Gerdenis Kodis
- School of Molecular Sciences
- Arizona State University
- Tempe
- USA
| | - Ana L. Moore
- School of Molecular Sciences
- Arizona State University
- Tempe
- USA
| | - Devens Gust
- School of Molecular Sciences
- Arizona State University
- Tempe
- USA
| | - Thomas A. Moore
- School of Molecular Sciences
- Arizona State University
- Tempe
- USA
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23
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Drmota Prebil S, Slapšak U, Pavšič M, Ilc G, Puž V, de Almeida Ribeiro E, Anrather D, Hartl M, Backman L, Plavec J, Lenarčič B, Djinović-Carugo K. Structure and calcium-binding studies of calmodulin-like domain of human non-muscle α-actinin-1. Sci Rep 2016; 6:27383. [PMID: 27272015 PMCID: PMC4895382 DOI: 10.1038/srep27383] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 05/16/2016] [Indexed: 12/11/2022] Open
Abstract
The activity of several cytosolic proteins critically depends on the concentration of calcium ions. One important intracellular calcium-sensing protein is α-actinin-1, the major actin crosslinking protein in focal adhesions and stress fibers. The actin crosslinking activity of α-actinin-1 has been proposed to be negatively regulated by calcium, but the underlying molecular mechanisms are poorly understood. To address this, we determined the first high-resolution NMR structure of its functional calmodulin-like domain (CaMD) in calcium-bound and calcium-free form. These structures reveal that in the absence of calcium, CaMD displays a conformationally flexible ensemble that undergoes a structural change upon calcium binding, leading to limited rotation of the N- and C-terminal lobes around the connecting linker and consequent stabilization of the calcium-loaded structure. Mutagenesis experiments, coupled with mass-spectrometry and isothermal calorimetry data designed to validate the calcium binding stoichiometry and binding site, showed that human non-muscle α-actinin-1 binds a single calcium ion within the N-terminal lobe. Finally, based on our structural data and analogy with other α-actinins, we provide a structural model of regulation of the actin crosslinking activity of α-actinin-1 where calcium induced structural stabilisation causes fastening of the juxtaposed actin binding domain, leading to impaired capacity to crosslink actin.
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Affiliation(s)
- Sara Drmota Prebil
- Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI-1000 Ljubljana, Slovenia
| | - Urška Slapšak
- Slovenian NMR Centre, National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana, Slovenia
| | - Miha Pavšič
- Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI-1000 Ljubljana, Slovenia
| | - Gregor Ilc
- Slovenian NMR Centre, National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana, Slovenia.,EN-FIST Centre of Excellence, Trg Osvobodilne fronte 13, SI-1000 Ljubljana, Slovenia
| | - Vid Puž
- Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI-1000 Ljubljana, Slovenia
| | - Euripedes de Almeida Ribeiro
- Department of Structural and Computational Biology, Max F. Perutz Laboratories (MFPL), University of Vienna, Campus Vienna Biocenter 5, A-1030 Vienna, Austria
| | - Dorothea Anrather
- Mass Spectrometry Service Facility, Max F. Perutz Laboratories (MFPL), University of Vienna, Vienna Biocenter (VBC), Dr. Bohr-Gasse 3, A-1030 Vienna, Austria
| | - Markus Hartl
- Mass Spectrometry Service Facility, Max F. Perutz Laboratories (MFPL), University of Vienna, Vienna Biocenter (VBC), Dr. Bohr-Gasse 3, A-1030 Vienna, Austria
| | - Lars Backman
- Department of Chemistry, Umeå University, Linnaeus väg 10, SE-90187 Umeå, Sweden
| | - Janez Plavec
- Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI-1000 Ljubljana, Slovenia.,Slovenian NMR Centre, National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana, Slovenia.,EN-FIST Centre of Excellence, Trg Osvobodilne fronte 13, SI-1000 Ljubljana, Slovenia
| | - Brigita Lenarčič
- Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI-1000 Ljubljana, Slovenia.,Department of Biochemistry, Molecular Biology and Structural Biology, Jožef Stefan Institute, Jamova 39,SI-1000 Ljubljana, Slovenia
| | - Kristina Djinović-Carugo
- Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI-1000 Ljubljana, Slovenia.,Department of Structural and Computational Biology, Max F. Perutz Laboratories (MFPL), University of Vienna, Campus Vienna Biocenter 5, A-1030 Vienna, Austria
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24
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Halling DB, Liebeskind BJ, Hall AW, Aldrich RW. Conserved properties of individual Ca2+-binding sites in calmodulin. Proc Natl Acad Sci U S A 2016; 113:E1216-25. [PMID: 26884197 PMCID: PMC4780646 DOI: 10.1073/pnas.1600385113] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Calmodulin (CaM) is a Ca(2+)-sensing protein that is highly conserved and ubiquitous in eukaryotes. In humans it is a locus of life-threatening cardiomyopathies. The primary function of CaM is to transduce Ca(2+) concentration into cellular signals by binding to a wide range of target proteins in a Ca(2+)-dependent manner. We do not fully understand how CaM performs its role as a high-fidelity signal transducer for more than 300 target proteins, but diversity among its four Ca(2+)-binding sites, called EF-hands, may contribute to CaM's functional versatility. We therefore looked at the conservation of CaM sequences over deep evolutionary time, focusing primarily on the four EF-hand motifs. Expanding on previous work, we found that CaM evolves slowly but that its evolutionary rate is substantially faster in fungi. We also found that the four EF-hands have distinguishing biophysical and structural properties that span eukaryotes. These results suggest that all eukaryotes require CaM to decode Ca(2+) signals using four specialized EF-hands, each with specific, conserved traits. In addition, we provide an extensive map of sites associated with target proteins and with human disease and correlate these with evolutionary sequence diversity. Our comprehensive evolutionary analysis provides a basis for understanding the sequence space associated with CaM function and should help guide future work on the relationship between structure, function, and disease.
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Affiliation(s)
- D Brent Halling
- Department of Neuroscience, University of Texas at Austin, Austin, TX 78712
| | - Benjamin J Liebeskind
- Department of Neuroscience, University of Texas at Austin, Austin, TX 78712; Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX 78712
| | - Amelia W Hall
- Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX 78712; Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712
| | - Richard W Aldrich
- Department of Neuroscience, University of Texas at Austin, Austin, TX 78712;
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25
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Gaburjakova J, Gaburjakova M. Cardiac ryanodine receptor: Selectivity for alkaline earth metal cations points to the EF-hand nature of luminal binding sites. Bioelectrochemistry 2016; 109:49-56. [PMID: 26849106 DOI: 10.1016/j.bioelechem.2016.01.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 01/21/2016] [Accepted: 01/24/2016] [Indexed: 11/18/2022]
Abstract
A growing body of evidence suggests that the regulation of cardiac ryanodine receptor (RYR2) by luminal Ca(2+) is mediated by luminal binding sites located on the RYR2 channel itself and/or its auxiliary protein, calsequestrin. The localization and structure of RYR2-resident binding sites are not known because of the lack of a high-resolution structure of RYR2 luminal regions. To obtain the first structural insight, we probed the RYR2 luminal face stripped of calsequestrin by alkaline earth metal divalents (M(2+): Mg(2+), Ca(2+), Sr(2+) or Ba(2+)). We show that the RYR2 response to caffeine at the single-channel level is significantly modified by the nature of luminal M(2+). Moreover, we performed competition experiments by varying the concentration of luminal M(2+) (Mg(2+), Sr(2+) or Ba(2+)) from 8 mM to 53 mM and investigated its ability to compete with 1mM luminal Ca(2+). We demonstrate that all tested M(2+) bind to exactly the same RYR2 luminal binding sites. Their affinities decrease in the order: Ca(2+)>Sr(2+)>Mg(2+)~Ba(2+), showing a strong correlation with the M(2+) affinity of the EF-hand motif. This indicates that the RYR2 luminal binding regions and the EF-hand motif likely share some structural similarities because the structure ties directly to the function.
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Affiliation(s)
- Jana Gaburjakova
- Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Health Sciences Pavilion, 840 05, Bratislava, Slovak Republic.
| | - Marta Gaburjakova
- Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Health Sciences Pavilion, 840 05, Bratislava, Slovak Republic.
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26
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Li Q, Yao L, Xia W, Lin S. Calculation of anharmonic effects in the unimolecular dissociation of M 2+(H 2O) 2(M = Be, Mg, and Ca). Mol Phys 2015. [DOI: 10.1080/00268976.2015.1036148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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27
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Pang CL, Yuan HB, Cao TG, Su JG, Chen YF, Liu H, Yu H, Zhang HL, Zhan Y, An HL, Han YB. Molecular simulation assisted identification of Ca(2+) binding residues in TMEM16A. J Comput Aided Mol Des 2015; 29:1035-43. [PMID: 26481648 DOI: 10.1007/s10822-015-9876-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 10/12/2015] [Indexed: 01/31/2023]
Abstract
Calcium-activated chloride channels (CaCCs) play vital roles in a variety of physiological processes. Transmembrane protein 16A (TMEM16A) has been confirmed as the molecular counterpart of CaCCs which greatly pushes the molecular insights of CaCCs forward. However, the detailed mechanism of Ca(2+) binding and activating the channel is still obscure. Here, we utilized a combination of computational and electrophysiological approaches to discern the molecular mechanism by which Ca(2+) regulates the gating of TMEM16A channels. The simulation results show that the first intracellular loop serves as a Ca(2+) binding site including D439, E444 and E447. The experimental results indicate that a novel residue, E447, plays key role in Ca(2+) binding. Compared with WT TMEM16A, E447Y produces a 30-fold increase in EC50 of Ca(2+) activation and leads to a 100-fold increase in Ca(2+) concentrations that is needed to fully activate the channel. The following steered molecular dynamic (SMD) simulation data suggests that the mutations at 447 reduce the Ca(2+) dissociation energy. Our results indicated that both the electrical property and the size of the side-chain at residue 447 have significant effects on Ca(2+) dependent gating of TMEM16A.
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Affiliation(s)
- Chun-Li Pang
- Key laboratory of Molecular Biophysics, Tianjin, Hebei Province, China
- Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Hong-Bo Yuan
- Key laboratory of Molecular Biophysics, Tianjin, Hebei Province, China
- Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Tian-Guang Cao
- Key laboratory of Molecular Biophysics, Tianjin, Hebei Province, China
- Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Ji-Guo Su
- School of Sciences, Yanshan University, Qinhuangdao, China
| | - Ya-Fei Chen
- Key laboratory of Molecular Biophysics, Tianjin, Hebei Province, China
- Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Hui Liu
- Key laboratory of Molecular Biophysics, Tianjin, Hebei Province, China
- Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Hui Yu
- Key laboratory of Molecular Biophysics, Tianjin, Hebei Province, China
- Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Hai-Ling Zhang
- Key Laboratory of Neural and Vascular Biology, Ministry of Education, Shijiazhuang, China
- The Key Laboratory of Pharmacology and Toxicology for New Drug, Shijiazhuang, Hebei Province, China
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | - Yong Zhan
- Key laboratory of Molecular Biophysics, Tianjin, Hebei Province, China.
- Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China.
| | - Hai-Long An
- Key laboratory of Molecular Biophysics, Tianjin, Hebei Province, China.
- Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China.
| | - Yue-Bin Han
- Key laboratory of Molecular Biophysics, Tianjin, Hebei Province, China
- Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
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28
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Saxena A, García AE. Multisite ion model in concentrated solutions of divalent cations (MgCl2 and CaCl2): osmotic pressure calculations. J Phys Chem B 2015; 119:219-27. [PMID: 25482831 PMCID: PMC4291043 DOI: 10.1021/jp507008x] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Revised: 12/03/2014] [Indexed: 01/09/2023]
Abstract
Accurate force field parameters for ions are essential for meaningful simulation studies of proteins and nucleic acids. Currently accepted models of ions, especially for divalent ions, do not necessarily reproduce the right physiological behavior of Ca(2+) and Mg(2+) ions. Saxena and Sept (J. Chem. Theor. Comput. 2013, 9, 3538-3542) described a model, called the multisite-ion model, where instead of treating the ions as an isolated sphere, the charge was split into multiple sites with partial charge. This model provided accurate inner shell coordination of the ion with biomolecules and predicted better free energies for proteins and nucleic acids. Here, we expand and refine the multisite model to describe the behavior of divalent ions in concentrated MgCl2 and CaCl2 electrolyte solutions, eliminating the unusual ion-ion pairing and clustering of ions which occurred in the original model. We calibrate and improve the parameters of the multisite model by matching the osmotic pressure of concentrated solutions of MgCl2 to the experimental values and then use these parameters to test the behavior of CaCl2 solutions. We find that the concentrated solutions of both divalent ions exhibit the experimentally observed behavior with correct osmotic pressure, the presence of solvent separated ion pairs instead of direct ion pairs, and no aggregation of ions. The improved multisite model for (Mg(2+) and Ca(2+)) can be used in classical simulations of biomolecules at physiologically relevant salt concentrations.
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Affiliation(s)
- Akansha Saxena
- Department of Physics, Applied
Physics, and Astronomy and The Center for Biotechnology and Interdisciplinary
Studies, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Angel E. García
- Department of Physics, Applied
Physics, and Astronomy and The Center for Biotechnology and Interdisciplinary
Studies, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
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Abstract
Recent advances in the AC (adenylate cyclase)/cAMP field reveal overarching roles for the ACs. Whereas few processes are unaffected by cAMP in eukaryotes, ranging from the rapid modulation of ion channel kinetics to the slowest developmental effects, the large number of cellular processes modulated by only three intermediaries, i.e. PKA (protein kinase A), Epacs (exchange proteins directly activated by cAMP) and CNG (cyclic nucleotide-gated) channels, poses the question of how selectivity and fine control is achieved by cAMP. One answer rests on the number of differently regulated and distinctly expressed AC species. Specific ACs are implicated in processes such as insulin secretion, immunological responses, sino-atrial node pulsatility and memory formation, and specific ACs are linked with particular diseased conditions or predispositions, such as cystic fibrosis, Type 2 diabetes and dysrhythmias. However, much of the selectivity and control exerted by cAMP lies in the sophisticated properties of individual ACs, in terms of their coincident responsiveness, dynamic protein scaffolding and organization of cellular microassemblies. The ACs appear to be the centre of highly organized microdomains, where both cAMP and Ca2+, the other major influence on ACs, change in patterns quite discrete from the broad cellular milieu. How these microdomains are organized is beginning to become clear, so that ACs may now be viewed as fundamental signalling centres, whose properties exceed their production of cAMP. In the present review, we summarize how ACs are multiply regulated and the steps that are put in place to ensure discrimination in their signalling. This includes scaffolding of targets and modulators by the ACs and assembling of signalling nexuses in discrete cellular domains. We also stress how these assemblies are cell-specific, context-specific and dynamic, and may be best addressed by targeted biosensors. These perspectives on the organization of ACs uncover new strategies for intervention in systems mediated by cAMP, which promise far more informed specificity than traditional approaches.
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Dimerization of peptides by calcium ions: investigation of a calcium-binding motif. INTERNATIONAL JOURNAL OF PROTEOMICS 2014; 2014:153712. [PMID: 25295190 PMCID: PMC4177772 DOI: 10.1155/2014/153712] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Accepted: 06/11/2014] [Indexed: 12/28/2022]
Abstract
We investigated calcium-binding motifs of peptides and their recognition of active functionalities for coordination. This investigation generates the fundamentals to design carrier material for calcium-bound peptide-peptide interactions. Interactions of different peptides with active calcium domains were investigated. Evaluation of selectivity was performed by electrospray ionization mass spectrometry by infusing solutions containing two different peptides (P1 and P2) in the presence of calcium ions. In addition to signals for monomer species, intense dimer signals are observed for the heterodimer ions (P1 ⋯ Ca2+ ⋯ P2) (⋯ represents the noncovalent binding of calcium with the peptide) in the positive ion mode and for ions ([P1-2H]2− ⋯ Ca2+ ⋯ [P2-2H]2−) in the negative ion mode. Monitoring of the dissociation from these mass selected dimer ions via the kinetic method provides information on the calcium affinity order of different peptide sequences.
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Calcium-dependent energetics of calmodulin domain interactions with regulatory regions of the Ryanodine Receptor Type 1 (RyR1). Biophys Chem 2014; 193-194:35-49. [PMID: 25145833 DOI: 10.1016/j.bpc.2014.07.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Revised: 07/21/2014] [Accepted: 07/22/2014] [Indexed: 01/09/2023]
Abstract
Calmodulin (CaM) allosterically regulates the homo-tetrameric human Ryanodine Receptor Type 1 (hRyR1): apo CaM activates the channel, while (Ca(2+))4-CaM inhibits it. CaM-binding RyR1 residues 1975-1999 and 3614-3643 were proposed to allow CaM to bridge adjacent RyR1 subunits. Fluorescence anisotropy titrations monitored the binding of CaM and its domains to peptides encompassing hRyR(11975-1999) or hRyR1(3614-3643). Both CaM and its C-domain associated in a calcium-independent manner with hRyR1(3614-3643) while N-domain required calcium and bound ~250-fold more weakly. Association with hRyR1(11975-1999) was weak. Both hRyR1 peptides increased the calcium-binding affinity of both CaM domains, while maintaining differences between them. These energetics support the CaM C-domain association with hRyR1(3614-3643) at low calcium, positioning CaM to respond to calcium efflux. However, the CaM N-domain affinity for hRyR(11975-1999) alone was insufficient to support CaM bridging adjacent RyR1 subunits. Other proteins or elements of the hRyR1 structure must contribute to the energetics of CaM-mediated regulation.
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32
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Xiao Q, Cui Y. Acidic amino acids in the first intracellular loop contribute to voltage- and calcium- dependent gating of anoctamin1/TMEM16A. PLoS One 2014; 9:e99376. [PMID: 24901998 PMCID: PMC4047086 DOI: 10.1371/journal.pone.0099376] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 05/13/2014] [Indexed: 11/18/2022] Open
Abstract
Anoctamin1 (Ano1, or TMEM16A) is a Ca2+-activated chloride channel that is gated by both voltage and Ca2+. We have previously identified that the first intracellular loop that contains a high density of acidic residues mediates voltage- and calcium-dependent gating of Ano1. Mutation of the four consecutive glutamates (444EEEE447) inhibits the voltage-dependent activation of Ano1, whereas deletion of these residues decreases apparent Ca2+ sensitivity. In the present study, we further found that deletion of 444EEEEEAVKD452 produced a more than 40-fold decrease in the apparent Ca2+ sensitivity with altered activation kinetics. We then systematically mutated each acidic residue into alanine, and analyzed the voltage- and calcium dependent activation of each mutation. Activation kinetics of wild type Ano1 consisted of a fast component (τfast) that represented voltage-dependent mode, and a slow component (τslow) that reflected the Ca2+-dependent modal gating. E444A, E445A, E446A, E447A, E448A, and E457A mutations showed a decrease in the τfast, significantly inhibited voltage-dependent activation of Ano1 in the absence of Ca2+, and greatly shifted the G-V curve to the right, suggesting that these glutamates are involved in voltage-gating of Ano1. Furthermore, D452A, E464A, E470A, and E475A mutations that did not alter voltage-dependent activation of the channel, significantly decreased Ca2+ dependence of G-V curve, exhibited an increase in the τslow, and produced a 2-3 fold decrease in the apparent Ca2+ sensitivity, suggesting that these acidic residues are involved in Ca2+-dependent gating of the channel. Our data show that acidic residues in the first intracellular loop are the important structural determinant that couples the voltage and calcium dependent gating of Ano1.
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Affiliation(s)
- Qinghuan Xiao
- From the Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, Shenyang, China
- * E-mail:
| | - Yuanyuan Cui
- Department of Cell biology, School of Medicine, Emory University, Atlanta, Georgia, United States of America
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33
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Kahlen J, Salimi L, Sulpizi M, Peter C, Donadio D. Interaction of Charged Amino-Acid Side Chains with Ions: An Optimization Strategy for Classical Force Fields. J Phys Chem B 2014; 118:3960-72. [DOI: 10.1021/jp412490c] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jens Kahlen
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Leila Salimi
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Johannes Gutenberg University Mainz, Staudinger Weg 7, 55099 Mainz, Germany
| | - Marialore Sulpizi
- Johannes Gutenberg University Mainz, Staudinger Weg 7, 55099 Mainz, Germany
| | - Christine Peter
- University of Konstanz, P.O. Box 718, 78547 Konstanz, Germany
| | - Davide Donadio
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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34
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RONG Z, MA L, LIU B, TIAN Y, YANG B. Electrochemistry of Eu(III) Binding to N-terminal of Euplotes Octocarinatus Centrin. ELECTROCHEMISTRY 2014. [DOI: 10.5796/electrochemistry.82.663] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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35
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Lee CI, Brudvig GW. Investigation of the Functional Role of Ca2+in the Oxygen-Evolving Complex of Photosystem II: A pH-Dependence Study of the Substitution of Ca2+by Sr2+. J CHIN CHEM SOC-TAIP 2013. [DOI: 10.1002/jccs.200400178] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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36
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Yuan H, Gao C, Chen Y, Jia M, Geng J, Zhang H, Zhan Y, Boland LM, An H. Divalent cations modulate TMEM16A calcium-activated chloride channels by a common mechanism. J Membr Biol 2013; 246:893-902. [PMID: 23996050 DOI: 10.1007/s00232-013-9589-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Accepted: 08/09/2013] [Indexed: 01/15/2023]
Abstract
The gating of Ca²⁺-activated Cl⁻ channels is controlled by a complex interplay among [Ca²⁺](i), membrane potential and permeant anions. Besides Ca²⁺, Ba²⁺ also can activate both TMEM16A and TMEM16B. This study reports the effects of several divalent cations as regulators of TMEM16A channels stably expressed in HEK293T cells. Among the divalent cations that activate TMEM16A, Ca²⁺ is most effective, followed by Sr²⁺ and Ni²⁺, which have similar affinity, while Mg²⁺ is ineffective. Zn²⁺ does not activate TMEM16A but inhibits the Ca²⁺-activated chloride currents. Maximally effective concentrations of Sr²⁺ and Ni²⁺ occluded activation of the TMEM16A current by Ca²⁺, which suggests that Ca²⁺, Sr²⁺ and Ni²⁺ all regulate the channel by the same mechanism.
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Affiliation(s)
- Hongbo Yuan
- Institute of Biophysics, School of Sciences, Hebei University of Technology, 5340 Xiping Road, Tianjin, 300401, People's Republic of China
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37
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Novel GUCA1A mutations suggesting possible mechanisms of pathogenesis in cone, cone-rod, and macular dystrophy patients. BIOMED RESEARCH INTERNATIONAL 2013; 2013:517570. [PMID: 24024198 PMCID: PMC3759255 DOI: 10.1155/2013/517570] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Accepted: 06/19/2013] [Indexed: 01/06/2023]
Abstract
Here, we report two novel GUCA1A (the gene for guanylate cyclase activating protein 1) mutations identified in unrelated Spanish families affected by autosomal dominant retinal degeneration (adRD) with cone and rod involvement. All patients from a three-generation adRD pedigree underwent detailed ophthalmic evaluation. Total genome scan using single-nucleotide polymorphisms and then the linkage analysis were undertaken on the pedigree. Haplotype analysis revealed a 55.37 Mb genomic interval cosegregating with the disease phenotype on chromosome 6p21.31-q15. Mutation screening of positional candidate genes found a heterozygous transition c.250C>T in exon 4 of GUCA1A, corresponding to a novel mutation p.L84F. A second missense mutation, c.320T>C (p.I107T), was detected by screening of the gene in a Spanish patients cohort. Using bioinformatics approach, we predicted that either haploinsufficiency or dominant-negative effect accompanied by creation of a novel function for the mutant protein is a possible mechanism of the disease due to c.250C>T and c.320T>C. Although additional functional studies are required, our data in relation to the c.250C>T mutation open the possibility that transacting factors binding to de novo created recognition site resulting in formation of aberrant splicing variant is a disease model which may be more widespread than previously recognized as a mechanism causing inherited RD.
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38
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Saxena A, Sept D. Multisite Ion Models That Improve Coordination and Free Energy Calculations in Molecular Dynamics Simulations. J Chem Theory Comput 2013; 9:3538-42. [DOI: 10.1021/ct400177g] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Akansha Saxena
- Department
of Biomedical Engineering and Center for Computational Medicine and
Bioinformatics, University of Michigan,
Ann Arbor, Michigan 48109, United States
- Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180,
United States
| | - David Sept
- Department
of Biomedical Engineering and Center for Computational Medicine and
Bioinformatics, University of Michigan,
Ann Arbor, Michigan 48109, United States
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39
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Gong P, Kortus MG, Nix JC, Davis RE, Peersen OB. Structures of coxsackievirus, rhinovirus, and poliovirus polymerase elongation complexes solved by engineering RNA mediated crystal contacts. PLoS One 2013; 8:e60272. [PMID: 23667424 PMCID: PMC3648537 DOI: 10.1371/journal.pone.0060272] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 02/26/2013] [Indexed: 01/03/2023] Open
Abstract
RNA-dependent RNA polymerases play a vital role in the growth of RNA viruses where they are responsible for genome replication, but do so with rather low fidelity that allows for the rapid adaptation to different host cell environments. These polymerases are also a target for antiviral drug development. However, both drug discovery efforts and our understanding of fidelity determinants have been hampered by a lack of detailed structural information about functional polymerase-RNA complexes and the structural changes that take place during the elongation cycle. Many of the molecular details associated with nucleotide selection and catalysis were revealed in our recent structure of the poliovirus polymerase-RNA complex solved by first purifying and then crystallizing stalled elongation complexes. In the work presented here we extend that basic methodology to determine nine new structures of poliovirus, coxsackievirus, and rhinovirus elongation complexes at 2.2-2.9 Å resolution. The structures highlight conserved features of picornaviral polymerases and the interactions they make with the template and product RNA strands, including a tight grip on eight basepairs of the nascent duplex, a fully pre-positioned templating nucleotide, and a conserved binding pocket for the +2 position template strand base. At the active site we see a pre-bound magnesium ion and there is conservation of a non-standard backbone conformation of the template strand in an interaction that may aid in triggering RNA translocation via contact with the conserved polymerase motif B. Moreover, by engineering plasticity into RNA-RNA contacts, we obtain crystal forms that are capable of multiple rounds of in-crystal catalysis and RNA translocation. Together, the data demonstrate that engineering flexible RNA contacts to promote crystal lattice formation is a versatile platform that can be used to solve the structures of viral RdRP elongation complexes and their catalytic cycle intermediates.
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Affiliation(s)
- Peng Gong
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Matthew G. Kortus
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Jay C. Nix
- Molecular Biology Consortium, Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Ralph E. Davis
- Cocrystal Discovery Inc., Mountain View, California, United States of America
| | - Olve B. Peersen
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, United States of America
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40
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Springer CL, Huntoon HP, Peersen OB. Polyprotein context regulates the activity of poliovirus 2CATPase bound to bilayer nanodiscs. J Virol 2013; 87:5994-6004. [PMID: 23514879 PMCID: PMC3648184 DOI: 10.1128/jvi.03491-12] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 03/11/2013] [Indexed: 12/26/2022] Open
Abstract
Positive-strand RNA viruses generally replicate in large membrane-associated complexes. For poliovirus, these replication complexes are anchored to the membrane via the viral 2B, 2C, and 3A proteins. 2C is an AAA+ family ATPase that plays a key role in host cell membrane rearrangement, is a putative helicase, and is implicated in virion assembly and packaging. However, the membrane-binding characteristics of all of these viral proteins have made it difficult to elucidate their exact roles in virus replication. We show here that small lipid bilayers known as nanodiscs can be used to chaperone the in vitro expression of soluble poliovirus 2C, 2BC, and 2BC3AB polyproteins in a membrane-bound form. ATPase assays on these proteins show that the activity of the core 2C domain is stimulated ~0-fold compared to the larger 2BC3AB polyprotein, with most of this stimulation occurring upon removal of 2B. The proteins are active over a wide range of salt concentrations, exhibit slight lipid headgroup dependence, and show significant stimulation by acetate. Our data lead to a model wherein the replication complex can be assembled with a minimally active form of 2C that then becomes fully activated by proteolytic cleavage from the adjacent 2B viroporin domain.
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Affiliation(s)
- Courtney L Springer
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, USA
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41
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Reprogramming EF-hands for design of catalytically amplified lanthanide sensors. J Biol Inorg Chem 2013; 18:411-8. [PMID: 23420322 DOI: 10.1007/s00775-013-0985-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2012] [Accepted: 01/30/2013] [Indexed: 01/12/2023]
Abstract
We recently reported that a computationally designed catalyst nicknamed AlleyCat facilitates C-H proton abstraction in Kemp elimination at neutral pH in a selective and calcium-dependent fashion by a factor of approximately 100,000 (Korendovych et al. in Proc. Natl. Acad. Sci. USA 108:6823, 2011). Kemp elimination produced a colored product that can be easily read out, thus making AlleyCat a catalytically amplified metal sensor for calcium. Here we report that metal-binding EF-hand motifs in AlleyCat could be redesigned to incorporate trivalent metal ions without significant loss of catalytic activity. Mutation of a single neutral residue at position 9 of each of the EF-hands to glutamate results in almost a two orders of magnitude improvement of selectivity for trivalent metal ions over calcium. Development of this new lanthanide-dependent switchable Kemp eliminase, named CuSeCat EE, provides the foundation for further selectivity improvement and broadening the scope of the repertoire of metals for sensing. A concerted effort in the design of switchable enzymes has many environmental, sensing, and metal ion tracking applications.
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42
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Wang W, Barnabei MS, Asp ML, Heinis FI, Arden E, Davis J, Braunlin E, Li Q, Davis JP, Potter JD, Metzger JM. Noncanonical EF-hand motif strategically delays Ca2+ buffering to enhance cardiac performance. Nat Med 2013; 19:305-12. [PMID: 23396207 DOI: 10.1038/nm.3079] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Accepted: 12/21/2012] [Indexed: 12/26/2022]
Abstract
EF-hand proteins are ubiquitous in cell signaling. Parvalbumin (Parv), the archetypal EF-hand protein, is a high-affinity Ca(2+) buffer in many biological systems. Given the centrality of Ca(2+) signaling in health and disease, EF-hand motifs designed to have new biological activities may have widespread utility. Here, an EF-hand motif substitution that had been presumed to destroy EF-hand function, that of glutamine for glutamate at position 12 of the second cation binding loop domain of Parv (ParvE101Q), markedly inverted relative cation affinities: Mg(2+) affinity increased, whereas Ca(2+) affinity decreased, forming a new ultra-delayed Ca(2+) buffer with favorable properties for promoting cardiac relaxation. In therapeutic testing, expression of ParvE101Q fully reversed the severe myocyte intrinsic contractile defect inherent to expression of native Parv and corrected abnormal myocardial relaxation in diastolic dysfunction disease models in vitro and in vivo. Strategic design of new EF-hand motif domains to modulate intracellular Ca(2+) signaling could benefit many biological systems with abnormal Ca(2+) handling, including the diseased heart.
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Affiliation(s)
- Wang Wang
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, Minnesota, USA
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43
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Asp ML, Martindale JJ, Heinis FI, Wang W, Metzger JM. Calcium mishandling in diastolic dysfunction: mechanisms and potential therapies. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:895-900. [PMID: 23022395 DOI: 10.1016/j.bbamcr.2012.09.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 09/18/2012] [Accepted: 09/20/2012] [Indexed: 01/11/2023]
Abstract
Diastolic dysfunction is characterized by slow or incomplete relaxation of the ventricles during diastole, and is an important contributor to heart failure pathophysiology. Clinical symptoms include fatigue, shortness of breath, and pulmonary and peripheral edema, all contributing to decreased quality of life and poor prognosis. There are currently no therapies available that directly target the heart pump defects in diastolic function. Calcium mishandling is a hallmark of heart disease and has been the subject of a large body of research. Efforts are ongoing in a number of gene therapy approaches to normalize the function of calcium handling proteins such as sarcoplasmic reticulum calcium ATPase. An alternative approach to address calcium mishandling in diastolic dysfunction is to introduce calcium buffers to facilitate relaxation of the heart. Parvalbumin is a calcium binding protein found in fast-twitch skeletal muscle and not normally expressed in the heart. Gene transfer of parvalbumin into normal and diseased cardiac myocytes increases relaxation rate but also markedly decreases contraction amplitude. Although parvalbumin binds calcium in a delayed manner, it is not delayed enough to preserve full contractility. Factors contributing to the temporal nature of calcium buffering by parvalbumin are discussed in relation to remediation of diastolic dysfunction. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Cardiac Pathways of Differentiation, Metabolism and Contraction.
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Affiliation(s)
- Michelle L Asp
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, MN 55455, USA
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44
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Whittington AC, Moerland TS. Resurrecting prehistoric parvalbumins to explore the evolution of thermal compensation in extant Antarctic fish parvalbumins. J Exp Biol 2012; 215:3281-92. [PMID: 22693024 DOI: 10.1242/jeb.070615] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Parvalbumins (PVs) from Antarctic notothenioid fishes display a pattern of thermal adaptation that likely reflects evolutionary changes in protein conformational flexibility. We have used ancestral sequence reconstruction and homology modeling to identify two amino acid changes that could potentially account for the present thermal sensitivity pattern of Antarctic fish PVs compared with a PV from a theoretical warm-adapted ancestral fish. To test this hypothesis, ancient PVs were resurrected in the lab using PV from the notothenioid Gobionotothen gibberifrons as a platform for introducing mutations comparable to the reconstructed ancestral PV sequences. The wild-type PV (WT) as well as three mutant expression constructs were engineered: lysine 8 to asparagine (K8N), lysine 26 to asparagine (K26N) and a double mutant (DM). Calcium equilibrium dissociation constants (K(d)) versus temperature curves for all mutants were right-shifted, as predicted, relative to that of WT PV. The K(d) values for the K8N and K26N single mutants were virtually identical at all temperatures and showed an intermediate level of thermal sensitivity. The DM construct displayed a full conversion of thermal sensitivity pattern to that of a PV from a warm/temperate-adapted fish. Additionally, the K(d) versus temperature curve for the WT construct revealed greater thermal sensitivity compared with the mutant constructs. Measurements of the rates of Ca(2+) dissociation (k(off)) showed that all mutants generally had slower k(off) values than WT at all temperatures. Calculated rates of Ca(2+) binding (k(on)) for the K8N and K26N mutants were similar to values for the WT PV at all temperatures. In contrast, the calculated k(on) values for the DM PV were faster, providing mechanistic insights into the nature of potentially adaptive changes in Ca(2+) binding in this PV. The overall results suggest that the current thermal phenotype of Antarctic PVs can be recapitulated by just two amino acid substitutions.
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Affiliation(s)
- A Carl Whittington
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA.
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45
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Zhao K, Wang X, Wong HC, Wohlhueter R, Kirberger MP, Chen G, Yang JJ. Predicting Ca2+ -binding sites using refined carbon clusters. Proteins 2012; 80:2666-79. [PMID: 22821762 DOI: 10.1002/prot.24149] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2012] [Revised: 06/14/2012] [Accepted: 07/11/2012] [Indexed: 12/13/2022]
Abstract
Identifying Ca(2+) -binding sites in proteins is the first step toward understanding the molecular basis of diseases related to Ca(2+) -binding proteins. Currently, these sites are identified in structures either through X-ray crystallography or NMR analysis. However, Ca(2+) -binding sites are not always visible in X-ray structures due to flexibility in the binding region or low occupancy in a Ca(2+) -binding site. Similarly, both Ca(2+) and its ligand oxygens are not directly observed in NMR structures. To improve our ability to predict Ca(2+) -binding sites in both X-ray and NMR structures, we report a new graph theory algorithm (MUG(C) ) to predict Ca(2+) -binding sites. Using carbon atoms covalently bonded to the chelating oxygen atoms, and without explicit reference to side-chain oxygen ligand co-ordinates, MUG(C) is able to achieve 94% sensitivity with 76% selectivity on a dataset of X-ray structures composed of 43 Ca(2+) -binding proteins. Additionally, prediction of Ca(2+) -binding sites in NMR structures was obtained by MUG(C) using a different set of parameters, which were determined by the analysis of both Ca(2+) -constrained and unconstrained Ca(2+) -loaded structures derived from NMR data. MUG(C) identified 20 of 21 Ca(2+) -binding sites in NMR structures inferred without the use of Ca(2+) constraints. MUG(C) predictions are also highly selective for Ca(2+) -binding sites as analyses of binding sites for Mg(2+) , Zn(2+) , and Pb(2+) were not identified as Ca(2+) -binding sites. These results indicate that the geometric arrangement of the second-shell carbon cluster is sufficient not only for accurate identification of Ca(2+) -binding sites in NMR and X-ray structures but also for selective differentiation between Ca(2+) and other relevant divalent cations.
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Affiliation(s)
- Kun Zhao
- Department of Mathematics and Statistics, Georgia State University, Atlanta, GA 30303, USA
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Barium ions selectively activate BK channels via the Ca2+-bowl site. Proc Natl Acad Sci U S A 2012; 109:11413-8. [PMID: 22733762 DOI: 10.1073/pnas.1204444109] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Activation of Ca(2+)-dependent BK channels is increased via binding of micromolar Ca(2+) to two distinct high-affinity sites per BK α-subunit. One site, termed the Ca(2+) bowl, is embedded within the second RCK domain (RCK2; regulator of conductance for potassium) of each α-subunit, while oxygen-containing residues in the first RCK domain (RCK1) have been linked to a separate Ca(2+) ligation site. Although both sites are activated by Ca(2+) and Sr(2+), Cd(2+) selectively favors activation via the RCK1 site. Divalent cations of larger ionic radius than Sr(2+) are thought to be ineffective at activating BK channels. Here we show that Ba(2+), better known as a blocker of K(+) channels, activates BK channels and that this effect arises exclusively from binding at the Ca(2+)-bowl site. Compared with previous estimates for Ca(2+) bowl-mediated activation by Ca(2+), the affinity of Ba(2+) to the Ca(2+) bowl is reduced about fivefold, and coupling of binding to activation is reduced from ∼3.6 for Ca(2+) to about ∼2.8 for Ba(2+). These results support the idea that ionic radius is an important determinant of selectivity differences among different divalent cations observed for each Ca(2+)-binding site.
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Soupene E, Kuypers FA. Phosphatidylcholine formation by LPCAT1 is regulated by Ca(2+) and the redox status of the cell. BMC BIOCHEMISTRY 2012; 13:8. [PMID: 22676268 PMCID: PMC3439698 DOI: 10.1186/1471-2091-13-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Accepted: 05/25/2012] [Indexed: 12/21/2022]
Abstract
Background Unsaturated fatty acids are susceptible to oxidation and damaged chains are removed from glycerophospholipids by phospholipase A2. De-acylated lipids are then re-acylated by lysophospholipid acyltransferase enzymes such as LPCAT1 which catalyses the formation of phosphatidylcholine (PC) from lysoPC and long-chain acyl-CoA. Results Activity of LPCAT1 is inhibited by Ca2+, and a Ca2+-binding motif of the EF-hand type, EFh-1, was identified in the carboxyl-terminal domain of the protein. The residues Asp-392 and Glu-403 define the loop of the hairpin structure formed by EFh-1. Substitution of D392 and E403 to alanine rendered an enzyme insensitive to Ca2+, which established that Ca2+ binding to that region negatively regulates the activity of the acyltransferase amino-terminal domain. Residue Cys-211 of the conserved motif III is not essential for catalysis and not sufficient for sensitivity to treatment by sulfhydryl-modifier agents. Among the several active cysteine-substitution mutants of LPCAT1 generated, we identified one to be resistant to treatment by sulfhydryl-alkylating and sulfhydryl-oxidizer agents. Conclusion Mutant forms of LPCAT1 that are not inhibited by Ca2+ and sulfhydryl-alkylating and –oxidizing agents will provide a better understanding of the physiological function of a mechanism that places the formation of PC, and the disposal of the bioactive species lysoPC, under the control of the redox status and Ca2+ concentration of the cell.
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Affiliation(s)
- Eric Soupene
- Children's Hospital Oakland Research Institute, 5700 Martin Luther King Jr, Way, Oakland, CA 94609, USA.
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Correlated variations in the parameters that regulate dendritic calcium signaling in mouse retinal ganglion cells. J Neurosci 2012; 31:18353-63. [PMID: 22171038 DOI: 10.1523/jneurosci.4212-11.2011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The amplitude and time course of stimulus-evoked second messenger signals carried by intracellular changes in free calcium ([Ca](free)) depend on the total influx of Ca(2+), the fraction bound to endogenous buffer and the rate of extrusion. Estimates of the values of these three parameters in proximal dendrites of 15 mouse α retinal ganglion cells were made using the "added buffer" method and found to vary greatly from one experiment to the next. The variations in the measured parameters were strongly correlated across the sample of cells. This reduced the variability in the amplitude and time course of the dendritic Ca(2+) signal and suggests that the expression of Ca(2+) channels, binding proteins and extrusion mechanisms is homeostatically coordinated to maintain the amplitude and kinetics of the Ca(2+) signal within a physiologically appropriate range.
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Gonzales AL, Earley S. Endogenous cytosolic Ca(2+) buffering is necessary for TRPM4 activity in cerebral artery smooth muscle cells. Cell Calcium 2012; 51:82-93. [PMID: 22153976 PMCID: PMC3265659 DOI: 10.1016/j.ceca.2011.11.004] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 10/28/2011] [Accepted: 11/14/2011] [Indexed: 10/14/2022]
Abstract
The melastatin transient receptor potential (TRP) channel, TRPM4, is a critical regulator of smooth muscle membrane potential and arterial tone. Activation of the channel is Ca(2+)-dependent, but prolonged exposures to high global Ca(2+) causes rapid inactivation under conventional whole-cell patch clamp conditions. Using amphotericin B perforated whole cell patch clamp electrophysiology, which minimally disrupts cytosolic Ca(2+) dynamics, we recently showed that Ca(2+) released from 1,2,5-triphosphate receptors (IP(3)R) on the sarcoplasmic reticulum (SR) activates TRPM4 channels, producing sustained transient inward cation currents (TICCs). Thus, Ca(2+)-dependent inactivation of TRPM4 may not be inherent to the channel itself but rather is a result of the recording conditions. We hypothesized that under conventional whole-cell configurations, loss of intrinsic cytosolic Ca(2+) buffering following cell dialysis contributes to inactivation of TRPM4 channels. With the inclusion of the Ca(2+) buffers ethylene glycol-bis(2-aminoethylether)-N,N,N',N'-tetraacetic acid (EGTA, 10mM) or bis-ethane-N,N,N',N'-tetraacetic acid (BAPTA, 0.1mM) in the pipette solution, we mimic endogenous Ca(2+) buffering and record novel, sustained whole-cell TICC activity from freshly-isolated cerebral artery myocytes. Biophysical properties of TICCs recorded under perforated and whole-cell patch clamp were nearly identical. Furthermore, whole-cell TICC activity was reduced by the selective TRPM4 inhibitor, 9-phenanthrol, and by siRNA-mediated knockdown of TRPM4. When a higher concentration (10mM) of BAPTA was included in the pipette solution, TICC activity was disrupted, suggesting that TRPM4 channels on the plasma membrane and IP(3)R on the SR are closely opposed but not physically coupled, and that endogenous Ca(2+) buffer proteins play a critical role in maintaining TRPM4 channel activity in native cerebral artery smooth muscle cells.
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Affiliation(s)
- Albert L Gonzales
- Vascular Physiology Research Group, Department of Biomedical Sciences Colorado State University Fort Collins, CO 80523-1617, USA
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Özçubukçu S, Mandal K, Wegner S, Jensen MP, He C. Selective Recognition of Americium by Peptide-Based Reagents. Inorg Chem 2011; 50:7937-9. [DOI: 10.1021/ic201094e] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | | | | | - Mark P. Jensen
- Chemical Science and Engineering Division, Argonne National Laboratory, Argonne, Illinois, 60439, United States
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