1
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O’Day DH. Calcium and Non-Penetrating Traumatic Brain Injury: A Proposal for the Implementation of an Early Therapeutic Treatment for Initial Head Insults. Biomolecules 2024; 14:853. [PMID: 39062567 PMCID: PMC11274459 DOI: 10.3390/biom14070853] [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: 05/29/2024] [Revised: 07/04/2024] [Accepted: 07/13/2024] [Indexed: 07/28/2024] Open
Abstract
Finding an effective treatment for traumatic brain injury is challenging for multiple reasons. There are innumerable different causes and resulting levels of damage for both penetrating and non-penetrating traumatic brain injury each of which shows diverse pathophysiological progressions. More concerning is that disease progression can take decades before neurological symptoms become obvious. Currently, the primary treatment for non-penetrating mild traumatic brain injury, also called concussion, is bed rest despite the fact the majority of emergency room visits for traumatic brain injury are due to this mild form. Furthermore, one-third of mild traumatic brain injury cases progress to long-term serious symptoms. This argues for the earliest therapeutic intervention for all mild traumatic brain injury cases which is the focus of this review. Calcium levels are greatly increased in damaged brain regions as a result of the initial impact due to tissue damage as well as disrupted ion channels. The dysregulated calcium level feedback is a diversity of ways to further augment calcium neurotoxicity. This suggests that targeting calcium levels and function would be a strong therapeutic approach. An effective calcium-based traumatic brain injury therapy could best be developed through therapeutic programs organized in professional team sports where mild traumatic brain injury events are common, large numbers of subjects are involved and professional personnel are available to oversee treatment and documentation. This review concludes with a proposal with that focus.
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Affiliation(s)
- Danton H. O’Day
- Department of Biology, University of Toronto Mississauga, Mississauga, ON L5L 1C6, Canada;
- Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
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2
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Greene D, Shiferaw Y. Identifying Key Binding Interactions Between the Cardiac L-Type Calcium Channel and Calmodulin Using Molecular Dynamics Simulations. J Phys Chem B 2024; 128:6097-6111. [PMID: 38870543 PMCID: PMC11215769 DOI: 10.1021/acs.jpcb.4c02251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Revised: 05/28/2024] [Accepted: 05/30/2024] [Indexed: 06/15/2024]
Abstract
Defects in the binding of the calcium sensing protein calmodulin (CaM) to the L-type calcium channel (CaV1.2) or to the ryanodine receptor type 2 (RyR2) can lead to dangerous cardiac arrhythmias with distinct phenotypes, such as long-QT syndrome (LQTS) and catecholaminergic ventricular tachycardia (CPVT). Certain CaM mutations lead to LQTS while other mutations lead to CPVT, but the mechanisms by which a specific mutation can lead to each disease phenotype are not well-understood. In this study, we use long, 2 μs molecular dynamics simulations and a multitrajectory approach to identify the key binding interactions between the IQ domain of CaV1.2 and CaM. Five key interactions are found between CaV1.2 and CaM in the C-lobe, 1 in the central linker, and 2 in the N-lobe. In addition, while 5 key interactions appear between residues 120-149 in the C-lobe of CaM when it interacts with CaV1.2, only 1 key interaction is found within this region of CaM when it interacts with the RyR2. We show that this difference in the distribution of key interactions correlates with the known distribution of CaM mutations that lead to LQTS or CPVT. This correlation suggests that a disruption of key binding interactions is a plausible mechanism that can lead to these two different disease phenotypes.
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Affiliation(s)
- D’Artagnan Greene
- Department of Physics and
Astronomy, California State University Northridge, 18111 Nordhoff Street, Northridge, California 91330-8268, United States of
America
| | - Yohannes Shiferaw
- Department of Physics and
Astronomy, California State University Northridge, 18111 Nordhoff Street, Northridge, California 91330-8268, United States of
America
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3
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O’Day DH. The Complex Interplay between Toxic Hallmark Proteins, Calmodulin-Binding Proteins, Ion Channels, and Receptors Involved in Calcium Dyshomeostasis in Neurodegeneration. Biomolecules 2024; 14:173. [PMID: 38397410 PMCID: PMC10886625 DOI: 10.3390/biom14020173] [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: 01/01/2024] [Revised: 01/23/2024] [Accepted: 01/30/2024] [Indexed: 02/25/2024] Open
Abstract
Calcium dyshomeostasis is an early critical event in neurodegeneration as exemplified by Alzheimer's (AD), Huntington's (HD) and Parkinson's (PD) diseases. Neuronal calcium homeostasis is maintained by a diversity of ion channels, buffers, calcium-binding protein effectors, and intracellular storage in the endoplasmic reticulum, mitochondria, and lysosomes. The function of these components and compartments is impacted by the toxic hallmark proteins of AD (amyloid beta and Tau), HD (huntingtin) and PD (alpha-synuclein) as well as by interactions with downstream calcium-binding proteins, especially calmodulin. Each of the toxic hallmark proteins (amyloid beta, Tau, huntingtin, and alpha-synuclein) binds to calmodulin. Multiple channels and receptors involved in calcium homeostasis and dysregulation also bind to and are regulated by calmodulin. The primary goal of this review is to show the complexity of these interactions and how they can impact research and the search for therapies. A secondary goal is to suggest that therapeutic targets downstream from calcium dyshomeostasis may offer greater opportunities for success.
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Affiliation(s)
- Danton H. O’Day
- Department of Biology, University of Toronto Mississauga, Mississauga, ON L5L 1C6, Canada;
- Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
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4
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Çınaroğlu S, Biggin PC. Computed Protein-Protein Enthalpy Signatures as a Tool for Identifying Conformation Sampling Problems. J Chem Inf Model 2023; 63:6095-6108. [PMID: 37759363 PMCID: PMC10565830 DOI: 10.1021/acs.jcim.3c01041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Indexed: 09/29/2023]
Abstract
Understanding the thermodynamic signature of protein-peptide binding events is a major challenge in computational chemistry. The complexity generated by both components possessing many degrees of freedom poses a significant issue for methods that attempt to directly compute the enthalpic contribution to binding. Indeed, the prevailing assumption has been that the errors associated with such approaches would be too large for them to be meaningful. Nevertheless, we currently have no indication of how well the present methods would perform in terms of predicting the enthalpy of binding for protein-peptide complexes. To that end, we carefully assembled and curated a set of 11 protein-peptide complexes where there is structural and isothermal titration calorimetry data available and then computed the absolute enthalpy of binding. The initial "out of the box" calculations were, as expected, very modest in terms of agreement with the experiment. However, careful inspection of the outliers allows for the identification of key sampling problems such as distinct conformations of peptide termini not being sampled or suboptimal cofactor parameters. Additional simulations guided by these aspects can lead to a respectable correlation with isothermal titration calorimetry (ITC) experiments (R2 of 0.88 and an RMSE of 1.48 kcal/mol overall). Although one cannot know prospectively whether computed ITC values will be correct or not, this work shows that if experimental ITC data are available, then this in conjunction with computed ITC, can be used as a tool to know if the ensemble being simulated is representative of the true ensemble or not. That is important for allowing the correct interpretation of the detailed dynamics of the system with respect to the measured enthalpy. The results also suggest that computational calorimetry is becoming increasingly feasible. We provide the data set as a resource for the community, which could be used as a benchmark to help further progress in this area.
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Affiliation(s)
| | - Philip C. Biggin
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, U.K.
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5
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Kameyama M, Minobe E, Shao D, Xu J, Gao Q, Hao L. Regulation of Cardiac Cav1.2 Channels by Calmodulin. Int J Mol Sci 2023; 24:ijms24076409. [PMID: 37047381 PMCID: PMC10094977 DOI: 10.3390/ijms24076409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 03/19/2023] [Accepted: 03/23/2023] [Indexed: 03/31/2023] Open
Abstract
Cav1.2 Ca2+ channels, a type of voltage-gated L-type Ca2+ channel, are ubiquitously expressed, and the predominant Ca2+ channel type, in working cardiac myocytes. Cav1.2 channels are regulated by the direct interactions with calmodulin (CaM), a Ca2+-binding protein that causes Ca2+-dependent facilitation (CDF) and inactivation (CDI). Ca2+-free CaM (apoCaM) also contributes to the regulation of Cav1.2 channels. Furthermore, CaM indirectly affects channel activity by activating CaM-dependent enzymes, such as CaM-dependent protein kinase II and calcineurin (a CaM-dependent protein phosphatase). In this article, we review the recent progress in identifying the role of apoCaM in the channel ‘rundown’ phenomena and related repriming of channels, and CDF, as well as the role of Ca2+/CaM in CDI. In addition, the role of CaM in channel clustering is reviewed.
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Affiliation(s)
- Masaki Kameyama
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Sakura-ga-oka, Kagoshima 890-8544, Japan
- Correspondence:
| | - Etsuko Minobe
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Sakura-ga-oka, Kagoshima 890-8544, Japan
| | - Dongxue Shao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang 110012, China (L.H.)
| | - Jianjun Xu
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Sakura-ga-oka, Kagoshima 890-8544, Japan
| | - Qinghua Gao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang 110012, China (L.H.)
| | - Liying Hao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang 110012, China (L.H.)
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6
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Calmodulin variant E140G associated with long QT syndrome impairs CaMKIIδ autophosphorylation and L-type calcium channel inactivation. J Biol Chem 2023; 299:102777. [PMID: 36496072 PMCID: PMC9830374 DOI: 10.1016/j.jbc.2022.102777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 11/29/2022] [Accepted: 12/01/2022] [Indexed: 12/13/2022] Open
Abstract
Long QT syndrome (LQTS) is a human inherited heart condition that can cause life-threatening arrhythmia including sudden cardiac death. Mutations in the ubiquitous Ca2+-sensing protein calmodulin (CaM) are associated with LQTS, but the molecular mechanism by which these mutations lead to irregular heartbeats is not fully understood. Here, we use a multidisciplinary approach including protein biophysics, structural biology, confocal imaging, and patch-clamp electrophysiology to determine the effect of the disease-associated CaM mutation E140G on CaM structure and function. We present novel data showing that mutant-regulated CaMKIIδ kinase activity is impaired with a significant reduction in enzyme autophosphorylation rate. We report the first high-resolution crystal structure of a LQTS-associated CaM variant in complex with the CaMKIIδ peptide, which shows significant structural differences, compared to the WT complex. Furthermore, we demonstrate that the E140G mutation significantly disrupted Cav1.2 Ca2+/CaM-dependent inactivation, while cardiac ryanodine receptor (RyR2) activity remained unaffected. In addition, we show that the LQTS-associated mutation alters CaM's Ca2+-binding characteristics, secondary structure content, and interaction with key partners involved in excitation-contraction coupling (CaMKIIδ, Cav1.2, RyR2). In conclusion, LQTS-associated CaM mutation E140G severely impacts the structure-function relationship of CaM and its regulation of CaMKIIδ and Cav1.2. This provides a crucial insight into the molecular factors contributing to CaM-mediated arrhythmias with a central role for CaMKIIδ.
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7
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Studying Peptide-Metal Ion Complex Structures by Solution-State NMR. Int J Mol Sci 2022; 23:ijms232415957. [PMID: 36555599 PMCID: PMC9782655 DOI: 10.3390/ijms232415957] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 12/06/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022] Open
Abstract
Metal chelation can provide structural stability and form reactive centers in metalloproteins. Approximately one third of known protein structures are metalloproteins, and metal binding, or the lack thereof, is often implicated in disease, making it necessary to be able to study these systems in detail. Peptide-metal complexes are both present in nature and can provide a means to focus on the binding region of a protein and control experimental variables to a high degree. Structural studies of peptide complexes with metal ions by nuclear magnetic resonance (NMR) were surveyed for all the essential metal complexes and many non-essential metal complexes. The various methods used to study each metal ion are presented together with examples of recent research. Many of these metal systems have been individually reviewed and this current overview of NMR studies of metallopeptide complexes aims to provide a basis for inspiration from structural studies and methodology applied in the field.
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8
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Ruiz-Fernández AR, Campos L, Gutierrez-Maldonado SE, Núñez G, Villanelo F, Perez-Acle T. Nanosecond Pulsed Electric Field (nsPEF): Opening the Biotechnological Pandora’s Box. Int J Mol Sci 2022; 23:ijms23116158. [PMID: 35682837 PMCID: PMC9181413 DOI: 10.3390/ijms23116158] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 05/23/2022] [Accepted: 05/23/2022] [Indexed: 02/04/2023] Open
Abstract
Nanosecond Pulsed Electric Field (nsPEF) is an electrostimulation technique first developed in 1995; nsPEF requires the delivery of a series of pulses of high electric fields in the order of nanoseconds into biological tissues or cells. They primary effects in cells is the formation of membrane nanopores and the activation of ionic channels, leading to an incremental increase in cytoplasmic Ca2+ concentration, which triggers a signaling cascade producing a variety of effects: from apoptosis up to cell differentiation and proliferation. Further, nsPEF may affect organelles, making nsPEF a unique tool to manipulate and study cells. This technique is exploited in a broad spectrum of applications, such as: sterilization in the food industry, seed germination, anti-parasitic effects, wound healing, increased immune response, activation of neurons and myocites, cell proliferation, cellular phenotype manipulation, modulation of gene expression, and as a novel cancer treatment. This review thoroughly explores both nsPEF’s history and applications, with emphasis on the cellular effects from a biophysics perspective, highlighting the role of ionic channels as a mechanistic driver of the increase in cytoplasmic Ca2+ concentration.
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Affiliation(s)
- Alvaro R. Ruiz-Fernández
- Computational Biology Lab, Centro Científico y Tecnológico de Excelencia Ciencia & Vida, Fundación Ciencia & Vida, Santiago 7780272, Chile; (L.C.); (S.E.G.-M.); (G.N.); (F.V.)
- Facultad de Ingeniería y Tecnología, Universidad San Sebastian, Bellavista 7, Santiago 8420524, Chile
- Correspondence: (A.R.R.-F.); (T.P.-A.)
| | - Leonardo Campos
- Computational Biology Lab, Centro Científico y Tecnológico de Excelencia Ciencia & Vida, Fundación Ciencia & Vida, Santiago 7780272, Chile; (L.C.); (S.E.G.-M.); (G.N.); (F.V.)
- Facultad de Ingeniería y Tecnología, Universidad San Sebastian, Bellavista 7, Santiago 8420524, Chile
| | - Sebastian E. Gutierrez-Maldonado
- Computational Biology Lab, Centro Científico y Tecnológico de Excelencia Ciencia & Vida, Fundación Ciencia & Vida, Santiago 7780272, Chile; (L.C.); (S.E.G.-M.); (G.N.); (F.V.)
- Facultad de Ingeniería y Tecnología, Universidad San Sebastian, Bellavista 7, Santiago 8420524, Chile
| | - Gonzalo Núñez
- Computational Biology Lab, Centro Científico y Tecnológico de Excelencia Ciencia & Vida, Fundación Ciencia & Vida, Santiago 7780272, Chile; (L.C.); (S.E.G.-M.); (G.N.); (F.V.)
| | - Felipe Villanelo
- Computational Biology Lab, Centro Científico y Tecnológico de Excelencia Ciencia & Vida, Fundación Ciencia & Vida, Santiago 7780272, Chile; (L.C.); (S.E.G.-M.); (G.N.); (F.V.)
- Facultad de Ingeniería y Tecnología, Universidad San Sebastian, Bellavista 7, Santiago 8420524, Chile
| | - Tomas Perez-Acle
- Computational Biology Lab, Centro Científico y Tecnológico de Excelencia Ciencia & Vida, Fundación Ciencia & Vida, Santiago 7780272, Chile; (L.C.); (S.E.G.-M.); (G.N.); (F.V.)
- Facultad de Ingeniería y Tecnología, Universidad San Sebastian, Bellavista 7, Santiago 8420524, Chile
- Correspondence: (A.R.R.-F.); (T.P.-A.)
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9
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Ishida H, Vogel HJ, Conner AC, Kitchen P, Bill RM, MacDonald JA. Simultaneous binding of the N- and C-terminal cytoplasmic domains of aquaporin 4 to calmodulin. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183837. [PMID: 34890582 DOI: 10.1016/j.bbamem.2021.183837] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 10/30/2021] [Accepted: 11/30/2021] [Indexed: 10/19/2022]
Abstract
Aquaporin 4 (AQP4) is a water transporting, transmembrane channel protein that has important regulatory roles in maintaining cellular water homeostasis. Several other AQP proteins exhibit calmodulin (CaM)-binding properties, and CaM has recently been implicated in the cell surface localization of AQP4. The objective of the present study was to assess the CaM-binding properties of AQP4 in detail. Inspection of AQP4 revealed two putative CaM-binding domains (CBDs) in the cytoplasmic N- and C-terminal regions, respectively. The Ca2+-dependent CaM-binding properties of AQP4 CBD peptides were assessed using fluorescence spectroscopy, isothermal titration calorimetry, and two-dimensional 1H, 15N-HSQC NMR with 15N-labeled CaM. The N-terminal CBD of AQP4 predominantly interacted with the N-lobe of CaM with a 1:1 binding ratio and a Kd of 3.4 μM. The C-terminal AQP4 peptide interacted with both the C- and N-lobes of CaM (2:1 binding ratio; Kd1: 3.6 μM, Kd2: 113.6 μM, respectively). A recombinant AQP4 protein domain (recAQP4CT, containing the entire cytosolic C-terminal sequence) bound CaM in a 1:1 binding mode with a Kd of 6.1 μM. A ternary bridging complex could be generated with the N- and C-lobes of CaM interacting simultaneously with the N- and C-terminal CBD peptides. These data support a unique adapter protein binding mode for CaM with AQP4.
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Affiliation(s)
- Hiroaki Ishida
- Biochemistry Research Group, Department of Biological Sciences, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Hans J Vogel
- Biochemistry Research Group, Department of Biological Sciences, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Alex C Conner
- College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Philip Kitchen
- College of Health and Life Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK
| | - Roslyn M Bill
- College of Health and Life Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK
| | - Justin A MacDonald
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4Z6, Canada.
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10
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Ames JB. L-Type Ca 2+ Channel Regulation by Calmodulin and CaBP1. Biomolecules 2021; 11:1811. [PMID: 34944455 PMCID: PMC8699282 DOI: 10.3390/biom11121811] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 11/30/2021] [Accepted: 11/30/2021] [Indexed: 01/12/2023] Open
Abstract
L-type voltage-gated Ca2+ channels (CaV1.2 and CaV1.3, called CaV) interact with the Ca2+ sensor proteins, calmodulin (CaM) and Ca2+ binding Protein 1 (CaBP1), that oppositely control Ca2+-dependent channel activity. CaM and CaBP1 can each bind to the IQ-motif within the C-terminal cytosolic domain of CaV, which promotes increased channel open probability under basal conditions. At elevated cytosolic Ca2+ levels (caused by CaV channel opening), Ca2+-bound CaM binding to CaV is essential for promoting rapid Ca2+-dependent channel inactivation (CDI). By contrast, CaV binding to CaBP1 prevents CDI and promotes Ca2+-induced channel opening (called CDF). In this review, I provide an overview of the known structures of CaM and CaBP1 and their structural interactions with the IQ-motif to help understand how CaM promotes CDI, whereas CaBP1 prevents CDI and instead promotes CDF. Previous electrophysiology studies suggest that Ca2+-free forms of CaM and CaBP1 may pre-associate with CaV under basal conditions. However, previous Ca2+ binding data suggest that CaM and CaBP1 are both calculated to bind to Ca2+ with an apparent dissociation constant of ~100 nM when CaM or CaBP1 is bound to the IQ-motif. Since the neuronal basal cytosolic Ca2+ concentration is ~100 nM, nearly half of the neuronal CaV channels are suggested to be bound to Ca2+-bound forms of either CaM or CaBP1 under basal conditions. The pre-association of CaV with calcified forms of CaM or CaBP1 are predicted here to have functional implications. The Ca2+-bound form of CaBP1 is proposed to bind to CaV under basal conditions to block CaV binding to CaM, which could explain how CaBP1 might prevent CDI.
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Affiliation(s)
- James B Ames
- Department of Chemistry, University of California, Davis, CA 95616, USA
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11
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Mahling R, Hovey L, Isbell HM, Marx DC, Miller MS, Kilpatrick AM, Weaver LD, Yoder JB, Kim EH, Andresen CNJ, Li S, Shea MA. Na V1.2 EFL domain allosterically enhances Ca 2+ binding to sites I and II of WT and pathogenic calmodulin mutants bound to the channel CTD. Structure 2021; 29:1339-1356.e7. [PMID: 33770503 PMCID: PMC8458505 DOI: 10.1016/j.str.2021.03.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 12/23/2020] [Accepted: 03/03/2021] [Indexed: 11/23/2022]
Abstract
Neuronal voltage-gated sodium channel NaV1.2 C-terminal domain (CTD) binds calmodulin (CaM) constitutively at its IQ motif. A solution structure (6BUT) and other NMR evidence showed that the CaM N domain (CaMN) is structurally independent of the C-domain (CaMC) whether CaM is bound to the NaV1.2IQp (1,901-1,927) or NaV1.2CTD (1,777-1,937) with or without calcium. However, in the CaM + NaV1.2CTD complex, the Ca2+ affinity of CaMN was more favorable than in free CaM, while Ca2+ affinity for CaMC was weaker than in the CaM + NaV1.2IQp complex. The CTD EF-like (EFL) domain allosterically widened the energetic gap between CaM domains. Cardiomyopathy-associated CaM mutants (N53I(N54I), D95V(D96V), A102V(A103V), E104A(E105A), D129G(D130G), and F141L(F142L)) all bound the NaV1.2 IQ motif favorably under resting (apo) conditions and bound calcium normally at CaMN sites. However, only N53I and A102V bound calcium at CaMC sites at [Ca2+] < 100 μM. Thus, they are expected to respond like wild-type CaM to Ca2+ spikes in excitable cells.
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Affiliation(s)
- Ryan Mahling
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Liam Hovey
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Holly M Isbell
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Dagan C Marx
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Mark S Miller
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Adina M Kilpatrick
- Department of Physics and Astronomy, Drake University, Des Moines, IA 50311-4516, USA
| | - Lisa D Weaver
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Jesse B Yoder
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Elaine H Kim
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Corinne N J Andresen
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Shuxiang Li
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Madeline A Shea
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1109, USA.
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12
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Hoang-Trong MT, Ullah A, Lederer WJ, Jafri MS. Cardiac Alternans Occurs through the Synergy of Voltage- and Calcium-Dependent Mechanisms. MEMBRANES 2021; 11:794. [PMID: 34677560 PMCID: PMC8539281 DOI: 10.3390/membranes11100794] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 10/08/2021] [Accepted: 10/12/2021] [Indexed: 11/24/2022]
Abstract
Cardiac alternans is characterized by alternating weak and strong beats of the heart. This signaling at the cellular level may appear as alternating long and short action potentials (APs) that occur in synchrony with alternating large and small calcium transients, respectively. Previous studies have suggested that alternans manifests itself through either a voltage dependent mechanism based upon action potential restitution or as a calcium dependent mechanism based on refractoriness of calcium release. We use a novel model of cardiac excitation-contraction (EC) coupling in the rat ventricular myocyte that includes 20,000 calcium release units (CRU) each with 49 ryanodine receptors (RyR2s) and 7 L-type calcium channels that are all stochastically gated. The model suggests that at the cellular level in the case of alternans produced by rapid pacing, the mechanism requires a synergy of voltage- and calcium-dependent mechanisms. The rapid pacing reduces AP duration and magnitude reducing the number of L-type calcium channels activating individual CRUs during each AP and thus increases the population of CRUs that can be recruited stochastically. Elevated myoplasmic and sarcoplasmic reticulum (SR) calcium, [Ca2+]myo and [Ca2+]SR respectively, increases ryanodine receptor open probability (Po) according to our model used in this simulation and this increased the probability of activating additional CRUs. A CRU that opens in one beat is less likely to open the subsequent beat due to refractoriness caused by incomplete refilling of the junctional sarcoplasmic reticulum (jSR). Furthermore, the model includes estimates of changes in Na+ fluxes and [Na+]i and thus provides insight into how changes in electrical activity, [Na+]i and sodium-calcium exchanger activity can modulate alternans. The model thus tracks critical elements that can account for rate-dependent changes in [Na+]i and [Ca2+]myo and how they contribute to the generation of Ca2+ signaling alternans in the heart.
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Affiliation(s)
- Minh Tuan Hoang-Trong
- Krasnow Institute for Advanced Study and School of Systems Biology, George Mason University, Fairfax, VA 22030, USA; (M.T.H.-T.); (A.U.)
| | - Aman Ullah
- Krasnow Institute for Advanced Study and School of Systems Biology, George Mason University, Fairfax, VA 22030, USA; (M.T.H.-T.); (A.U.)
| | - William Jonathan Lederer
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA;
| | - Mohsin Saleet Jafri
- Krasnow Institute for Advanced Study and School of Systems Biology, George Mason University, Fairfax, VA 22030, USA; (M.T.H.-T.); (A.U.)
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA;
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13
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Yaduvanshi S, Ero R, Kumar V. The mechanism of complex formation between calmodulin and voltage gated calcium channels revealed by molecular dynamics. PLoS One 2021; 16:e0258112. [PMID: 34610038 PMCID: PMC8491939 DOI: 10.1371/journal.pone.0258112] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Accepted: 09/18/2021] [Indexed: 11/18/2022] Open
Abstract
Calmodulin, a ubiquitous eukaryotic calcium sensor responsible for the regulation of many fundamental cellular processes, is a highly flexible protein and exhibits an unusually wide range of conformations. Furthermore, CaM is known to interact with more than 300 cellular targets. Molecular dynamics (MD) simulation trajectories suggest that EF-hand loops show different magnitudes of flexibility. Therefore, the four EF-hand motifs have different affinities for Ca2+ ions, which enables CaM to function on wide range of Ca2+ ion concentrations. EF-hand loops are 2-3 times more flexible in apo CaM whereas least flexible in Ca2+/CaM-IQ motif complexes. We report a unique intermediate conformation of Ca2+/CaM while transitioning from extended to compact form. We also report the complex formation process between Ca2+/CaM and IQ CaM-binding motifs. Our results showed how IQ motif recognise its binding site on the CaM and how CaM transforms from extended to compact form upon binding to IQ motif.
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Affiliation(s)
- Shivani Yaduvanshi
- Amity Institute of Molecular Medicine and Stem Cell Research (AIMMSCR), Amity University Noida, Noida, Uttar Pradesh, India
| | - Rya Ero
- Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
| | - Veerendra Kumar
- Amity Institute of Molecular Medicine and Stem Cell Research (AIMMSCR), Amity University Noida, Noida, Uttar Pradesh, India
- * E-mail:
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14
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Gaalswyk K, Liu Z, Vogel HJ, MacCallum JL. An Integrative Approach to Determine 3D Protein Structures Using Sparse Paramagnetic NMR Data and Physical Modeling. Front Mol Biosci 2021; 8:676268. [PMID: 34476238 PMCID: PMC8407082 DOI: 10.3389/fmolb.2021.676268] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 07/29/2021] [Indexed: 11/13/2022] Open
Abstract
Paramagnetic nuclear magnetic resonance (NMR) methods have emerged as powerful tools for structure determination of large, sparsely protonated proteins. However traditional applications face several challenges, including a need for large datasets to offset the sparsity of restraints, the difficulty in accounting for the conformational heterogeneity of the spin-label, and noisy experimental data. Here we propose an integrative approach to structure determination combining sparse paramagnetic NMR with physical modelling to infer approximate protein structural ensembles. We use calmodulin in complex with the smooth muscle myosin light chain kinase peptide as a model system. Despite acquiring data from samples labeled only at the backbone amide positions, we are able to produce an ensemble with an average RMSD of ∼2.8 Å from a reference X-ray crystal structure. Our approach requires only backbone chemical shifts and measurements of the paramagnetic relaxation enhancement and residual dipolar couplings that can be obtained from sparsely labeled samples.
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Affiliation(s)
- Kari Gaalswyk
- Department of Chemistry, University of Calgary, Calgary, AB, Canada
| | - Zhihong Liu
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Hans J. Vogel
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
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15
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Levchenko A, Vyalova NM, Nurgaliev T, Pozhidaev IV, Simutkin GG, Bokhan NA, Ivanova SA. NRG1, PIP4K2A, and HTR2C as Potential Candidate Biomarker Genes for Several Clinical Subphenotypes of Depression and Bipolar Disorder. Front Genet 2020; 11:936. [PMID: 33193575 PMCID: PMC7478333 DOI: 10.3389/fgene.2020.00936] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 07/27/2020] [Indexed: 12/20/2022] Open
Abstract
GSK3B, BDNF, NGF, NRG1, HTR2C, and PIP4K2A play important roles in molecular mechanisms of psychiatric disorders. GSK3B occupies a central position in these molecular mechanisms and is also modulated by psychotropic drugs. BDNF regulates a number of key aspects in neurodevelopment and synaptic plasticity. NGF exerts a trophic action and is implicated in cerebral alterations associated with psychiatric disorders. NRG1 is active in neural development, synaptic plasticity, and neurotransmission. HTR2C is another important psychopharmacological target. PIP4K2A catalyzes the phosphorylation of PI5P to form PIP2, the latter being implicated in various aspects of neuronal signal transduction. In the present study, the six genes were sequenced in a cohort of 19 patients with bipolar affective disorder, 41 patients with recurrent depressive disorder, and 55 patients with depressive episode. The study revealed a number of genetic variants associated with antidepressant treatment response, time to recurrence of episodes, and depression severity. Namely, alleles of rs35641374 and rs10508649 (NRG1 and PIP4K2A) may be prognostic biomarkers of time to recurrence of depressive and manic/mixed episodes among patients with bipolar affective disorder. Alleles of NC_000008.11:g.32614509_32614510del, rs61731109, and rs10508649 (also NRG1 and PIP4K2A) seem to be predictive biomarkers of response to pharmacological antidepressant treatment on the 28th day assessed by the HDRS-17 or CGI-I scale. In particular, the allele G of rs10508649 (PIP4K2A) may increase resistance to antidepressant treatment and be at the same time protective against recurrent manic/mixed episodes. These results support previous data indicating a biological link between resistance to antidepressant treatment and mania. Bioinformatic functional annotation of associated variants revealed possible impact for transcriptional regulation of PIP4K2A. In addition, the allele A of rs2248440 (HTR2C) may be a prognostic biomarker of depression severity. This allele decreases expression of the neighboring immune system gene IL13RA2 in the putamen according to the GTEx portal. The variant rs2248440 is near rs6318 (previously associated with depression and effects of psychotropic drugs) that is an eQTL for the same gene and tissue. Finally, the study points to several protein interactions relevant in the pathogenesis of mood disorders. Functional studies using cellular or animal models are warranted to support these results.
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Affiliation(s)
- Anastasia Levchenko
- Theodosius Dobzhansky Center for Genome Bioinformatics, Saint Petersburg State University, Saint Petersburg, Russia
| | - Natalia M Vyalova
- Tomsk National Research Medical Center, Mental Health Research Institute, Russian Academy of Sciences, Tomsk, Russia
| | - Timur Nurgaliev
- Institute of Translational Biomedicine, Saint Petersburg State University, Saint Petersburg, Russia
| | - Ivan V Pozhidaev
- Tomsk National Research Medical Center, Mental Health Research Institute, Russian Academy of Sciences, Tomsk, Russia
| | - German G Simutkin
- Tomsk National Research Medical Center, Mental Health Research Institute, Russian Academy of Sciences, Tomsk, Russia
| | - Nikolay A Bokhan
- Tomsk National Research Medical Center, Mental Health Research Institute, Russian Academy of Sciences, Tomsk, Russia.,National Research Tomsk State University, Tomsk, Russia.,Siberian State Medical University, Tomsk, Russia
| | - Svetlana A Ivanova
- Tomsk National Research Medical Center, Mental Health Research Institute, Russian Academy of Sciences, Tomsk, Russia.,Siberian State Medical University, Tomsk, Russia.,National Research Tomsk Polytechnic University, Tomsk, Russia
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16
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Chakouri N, Diaz J, Yang PS, Ben-Johny M. Ca V channels reject signaling from a second CaM in eliciting Ca 2+-dependent feedback regulation. J Biol Chem 2020; 295:14948-14962. [PMID: 32820053 DOI: 10.1074/jbc.ra120.013777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 08/18/2020] [Indexed: 11/06/2022] Open
Abstract
Calmodulin (CaM) regulation of voltage-gated calcium (CaV1-2) channels is a powerful Ca2+-feedback mechanism to adjust channel activity in response to Ca2+ influx. Despite progress in resolving mechanisms of CaM-CaV feedback, the stoichiometry of CaM interaction with CaV channels remains ambiguous. Functional studies that tethered CaM to CaV1.2 suggested that a single CaM sufficed for Ca2+ feedback, yet biochemical, FRET, and structural studies showed that multiple CaM molecules interact with distinct interfaces within channel cytosolic segments, suggesting that functional Ca2+ regulation may be more nuanced. Resolving this ambiguity is critical as CaM is enriched in subcellular domains where CaV channels reside, such as the cardiac dyad. We here localized multiple CaMs to the CaV nanodomain by tethering either WT or mutant CaM that lack Ca2+-binding capacity to the pore-forming α-subunit of CaV1.2, CaV1.3, and CaV2.1 and/or the auxiliary β2A subunit. We observed that a single CaM tethered to either the α or β2A subunit tunes Ca2+ regulation of CaV channels. However, when multiple CaMs are localized concurrently, CaV channels preferentially respond to signaling from the α-subunit-tethered CaM. Mechanistically, the introduction of a second IQ domain to the CaV1.3 carboxyl tail switched the apparent functional stoichiometry, permitting two CaMs to mediate functional regulation. In all, Ca2+ feedback of CaV channels depends exquisitely on a single CaM preassociated with the α-subunit carboxyl tail. Additional CaMs that colocalize with the channel complex are unable to trigger Ca2+-dependent feedback of channel gating but may support alternate regulatory functions.
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Affiliation(s)
- Nourdine Chakouri
- Department of Physiology and Cellular Biophysics, Columbia University, New York, New York, USA
| | - Johanna Diaz
- Department of Physiology and Cellular Biophysics, Columbia University, New York, New York, USA
| | - Philemon S Yang
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, USA
| | - Manu Ben-Johny
- Department of Physiology and Cellular Biophysics, Columbia University, New York, New York, USA.
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17
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Regulation of cardiovascular calcium channel activity by post-translational modifications or interacting proteins. Pflugers Arch 2020; 472:653-667. [PMID: 32435990 DOI: 10.1007/s00424-020-02398-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Revised: 05/04/2020] [Accepted: 05/06/2020] [Indexed: 02/08/2023]
Abstract
Voltage-gated calcium channels are the major pathway for Ca2+ influx to initiate the contraction of smooth and cardiac muscles. Alterations of calcium channel function have been implicated in multiple cardiovascular diseases, such as hypertension, atrial fibrillation, and long QT syndrome. Post-translational modifications do expand cardiovascular calcium channel structure and function to affect processes such as channel trafficking or polyubiquitination by two E3 ubiquitin ligases, Ret finger protein 2 (Rfp2) or murine double minute 2 protein (Mdm2). Additionally, biophysical property such as Ca2+-dependent inactivation (CDI) could be altered through binding of calmodulin, or channel activity could be modulated via S-nitrosylation by nitric oxide and phosphorylation by protein kinases or by interacting protein partners, such as galectin-1 and Rem. Understanding how cardiovascular calcium channel function is post-translationally remodeled under distinctive disease conditions will provide better information about calcium channel-related disease mechanisms and improve the development of more selective therapeutic agents for cardiovascular diseases.
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18
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Grant BMM, Enomoto M, Back SI, Lee KY, Gebregiworgis T, Ishiyama N, Ikura M, Marshall CB. Calmodulin disrupts plasma membrane localization of farnesylated KRAS4b by sequestering its lipid moiety. Sci Signal 2020; 13:13/625/eaaz0344. [PMID: 32234958 DOI: 10.1126/scisignal.aaz0344] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
KRAS4b is a small guanosine triphosphatase (GTPase) protein that regulates several signal transduction pathways that underlie cell proliferation, differentiation, and survival. KRAS4b function requires prenylation of its C terminus and recruitment to the plasma membrane, where KRAS4b activates effector proteins including the RAF family of kinases. The Ca2+-sensing protein calmodulin (CaM) has been suggested to regulate the localization of KRAS4b through direct, Ca2+-dependent interaction, but how CaM and KRAS4b functionally interact is controversial. Here, we determined a crystal structure, which was supported by solution nuclear magnetic resonance (NMR), that revealed the sequestration of the prenyl moiety of KRAS4b in the hydrophobic pocket of the C-terminal lobe of Ca2+-bound CaM. Our engineered fluorescence resonance energy transfer (FRET)-based biosensor probes (CaMeRAS) showed that, upon stimulation of Ca2+ influx by extracellular ligands, KRAS4b reversibly translocated in a Ca2+-CaM-dependent manner from the plasma membrane to the cytoplasm in live HeLa and HEK293 cells. These results reveal a mechanism underlying the inhibition of KRAS4b activity by Ca2+ signaling pathways.
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Affiliation(s)
- Benjamin M M Grant
- Princess Margaret Cancer Center, University Health Network, Toronto, Ontario M5G 1L7, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 1L7, Canada
| | - Masahiro Enomoto
- Princess Margaret Cancer Center, University Health Network, Toronto, Ontario M5G 1L7, Canada
| | - Sung-In Back
- Princess Margaret Cancer Center, University Health Network, Toronto, Ontario M5G 1L7, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 1L7, Canada
| | - Ki-Young Lee
- Princess Margaret Cancer Center, University Health Network, Toronto, Ontario M5G 1L7, Canada
| | - Teklab Gebregiworgis
- Princess Margaret Cancer Center, University Health Network, Toronto, Ontario M5G 1L7, Canada
| | - Noboru Ishiyama
- Princess Margaret Cancer Center, University Health Network, Toronto, Ontario M5G 1L7, Canada
| | - Mitsuhiko Ikura
- Princess Margaret Cancer Center, University Health Network, Toronto, Ontario M5G 1L7, Canada. .,Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 1L7, Canada
| | - Christopher B Marshall
- Princess Margaret Cancer Center, University Health Network, Toronto, Ontario M5G 1L7, Canada.
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19
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Wang K, Brohus M, Holt C, Overgaard MT, Wimmer R, Van Petegem F. Arrhythmia mutations in calmodulin can disrupt cooperativity of Ca 2+ binding and cause misfolding. J Physiol 2020; 598:1169-1186. [PMID: 32012279 DOI: 10.1113/jp279307] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 01/28/2020] [Indexed: 01/09/2023] Open
Abstract
KEY POINTS Mutations in the calmodulin protein (CaM) are associated with arrhythmia syndromes. This study focuses on understanding the structural characteristics of CaM disease mutants and their interactions with the voltage-gated calcium channel CaV 1.2. Arrhythmia mutations in CaM can lead to loss of Ca2+ binding, uncoupling of Ca2+ binding cooperativity, misfolding of the EF-hands and altered affinity for the calcium channel. These results help us to understand how different CaM mutants have distinct effects on structure and interactions with protein targets to cause disease. ABSTRACT Calmodulinopathies are life-threatening arrhythmia syndromes that arise from mutations in calmodulin (CaM), a calcium sensing protein whose sequence is completely conserved across all vertebrates. These mutations have been shown to interfere with the function of cardiac ion channels, including the voltage-gated Ca2+ channel CaV 1.2 and the ryanodine receptor (RyR2), in a mutation-specific manner. The ability of different CaM disease mutations to discriminate between these channels has been enigmatic. We present crystal structures of several C-terminal lobe mutants and an N-terminal lobe mutant in complex with the CaV 1.2 IQ domain, in conjunction with binding assays and complementary structural biology techniques. One mutation (D130G) causes a pathological conformation, with complete separation of EF-hands within the C-lobe and loss of Ca2+ binding in EF-hand 4. Another variant (Q136P) has severely reduced affinity for the IQ domain, and shows changes in the CD spectra under Ca2+ -saturating conditions when unbound to the IQ domain. Ca2+ binding to a pair of EF-hands normally proceeds with very high cooperativity, but we found that N98S CaM can adopt different conformations with either one or two Ca2+ ions bound to the C-lobe, possibly disrupting the cooperativity. An N-lobe variant (N54I), which causes severe stress-induced arrhythmia, does not show any major changes in complex with the IQ domain, providing a structural basis for why this mutant does not affect function of CaV 1.2. These findings show that different CaM mutants have distinct effects on both the CaM structure and interactions with protein targets, and act via distinct pathological mechanisms to cause disease.
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Affiliation(s)
- Kaiqian Wang
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, V6T 1Z3 Vancouver, BC, Canada
| | - Malene Brohus
- Department of Chemistry and Bioscience, Aalborg University, Aalborg, Denmark
| | - Christian Holt
- Department of Chemistry and Bioscience, Aalborg University, Aalborg, Denmark
| | | | - Reinhard Wimmer
- Department of Chemistry and Bioscience, Aalborg University, Aalborg, Denmark
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, V6T 1Z3 Vancouver, BC, Canada
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20
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Archer CR, Enslow BT, Taylor AB, De la Rosa V, Bhattacharya A, Shapiro MS. A mutually induced conformational fit underlies Ca 2+-directed interactions between calmodulin and the proximal C terminus of KCNQ4 K + channels. J Biol Chem 2019; 294:6094-6112. [PMID: 30808708 PMCID: PMC6463706 DOI: 10.1074/jbc.ra118.006857] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 02/24/2019] [Indexed: 11/06/2022] Open
Abstract
Calmodulin (CaM) conveys intracellular Ca2+ signals to KCNQ (Kv7, "M-type") K+ channels and many other ion channels. Whether this "calmodulation" involves a dramatic structural rearrangement or only slight perturbations of the CaM/KCNQ complex is as yet unclear. A consensus structural model of conformational shifts occurring between low nanomolar and physiologically high intracellular [Ca2+] is still under debate. Here, we used various techniques of biophysical chemical analyses to investigate the interactions between CaM and synthetic peptides corresponding to the A and B domains of the KCNQ4 subtype. We found that in the absence of CaM, the peptides are disordered, whereas Ca2+/CaM imposed helical structure on both KCNQ A and B domains. Isothermal titration calorimetry revealed that Ca2+/CaM has higher affinity for the B domain than for the A domain of KCNQ2-4 and much higher affinity for the B domain when prebound with the A domain. X-ray crystallography confirmed that these discrete peptides spontaneously form a complex with Ca2+/CaM, similar to previous reports of CaM binding KCNQ-AB domains that are linked together. Microscale thermophoresis and heteronuclear single-quantum coherence NMR spectroscopy indicated the C-lobe of Ca2+-free CaM to interact with the KCNQ4 B domain (Kd ∼10-20 μm), with increasing Ca2+ molar ratios shifting the CaM-B domain interactions via only the CaM C-lobe to also include the N-lobe. Our findings suggest that in response to increased Ca2+, CaM undergoes lobe switching that imposes a dramatic mutually induced conformational fit to both the proximal C terminus of KCNQ4 channels and CaM, likely underlying Ca2+-dependent regulation of KCNQ gating.
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Affiliation(s)
- Crystal R Archer
- From the Departments of Cell and Integrative Physiology, University of Texas Health San Antonio, San Antonio, Texas 78229; Departments of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, Texas 78229
| | - Benjamin T Enslow
- the Long School of Medicine, University of Texas Health San Antonio, San Antonio, Texas 78229
| | - Alexander B Taylor
- Departments of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, Texas 78229
| | - Victor De la Rosa
- From the Departments of Cell and Integrative Physiology, University of Texas Health San Antonio, San Antonio, Texas 78229
| | - Akash Bhattacharya
- Departments of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, Texas 78229
| | - Mark S Shapiro
- From the Departments of Cell and Integrative Physiology, University of Texas Health San Antonio, San Antonio, Texas 78229.
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21
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Pancaroglu R, Van Petegem F. Calcium Channelopathies: Structural Insights into Disorders of the Muscle Excitation–Contraction Complex. Annu Rev Genet 2018; 52:373-396. [DOI: 10.1146/annurev-genet-120417-031311] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Ion channels are membrane proteins responsible for the passage of ions down their electrochemical gradients and across biological membranes. In this, they generate and shape action potentials and provide secondary messengers for various signaling pathways. They are often part of larger complexes containing auxiliary subunits and regulatory proteins. Channelopathies arise from mutations in the genes encoding ion channels or their associated proteins. Recent advances in cryo-electron microscopy have resulted in an explosion of ion channel structures in multiple states, generating a wealth of new information on channelopathies. Disease-associated mutations fall into different categories, interfering with ion permeation, protein folding, voltage sensing, ligand and protein binding, and allosteric modulation of channel gating. Prime examples of these are Ca2+-selective channels expressed in myocytes, for which multiple structures in distinct conformational states have recently been uncovered. We discuss the latest insights into these calcium channelopathies from a structural viewpoint.
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Affiliation(s)
- Raika Pancaroglu
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
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22
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Arrhythmia mutations in calmodulin cause conformational changes that affect interactions with the cardiac voltage-gated calcium channel. Proc Natl Acad Sci U S A 2018; 115:E10556-E10565. [PMID: 30348784 DOI: 10.1073/pnas.1808733115] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Calmodulin (CaM) represents one of the most conserved proteins among eukaryotes and is known to bind and modulate more than a 100 targets. Recently, several disease-associated mutations have been identified in the CALM genes that are causative of severe cardiac arrhythmia syndromes. Although several mutations have been shown to affect the function of various cardiac ion channels, direct structural insights into any CaM disease mutation have been lacking. Here we report a crystallographic and NMR investigation of several disease mutant CaMs, linked to long-QT syndrome, in complex with the IQ domain of the cardiac voltage-gated calcium channel (CaV1.2). Surprisingly, two mutants (D95V, N97I) cause a major distortion of the C-terminal lobe, resulting in a pathological conformation not reported before. These structural changes result in altered interactions with the CaV1.2 IQ domain. Another mutation (N97S) reduces the affinity for Ca2+ by introducing strain in EF hand 3. A fourth mutant (F141L) shows structural changes in the Ca2+-free state that increase the affinity for the IQ domain. These results thus show that different mechanisms underlie the ability of CaM disease mutations to affect Ca2+-dependent inactivation of the voltage-gated calcium channel.
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23
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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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24
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Abstract
Calmodulin (CaM) regulation of voltage-gated calcium (CaV) channels is a powerful Ca2+ feedback mechanism that adjusts Ca2+ influx, affording rich mechanistic insights into Ca2+ decoding. CaM possesses a dual-lobed architecture, a salient feature of the myriad Ca2+-sensing proteins, where two homologous lobes that recognize similar targets hint at redundant signaling mechanisms. Here, by tethering CaM lobes, we demonstrate that bilobal architecture is obligatory for signaling to CaV channels. With one lobe bound, CaV carboxy tail rearranges itself, resulting in a preinhibited configuration precluded from Ca2+ feedback. Reconstitution of two lobes, even as separate molecules, relieves preinhibition and restores Ca2+ feedback. CaV channels thus detect the coincident binding of two Ca2+-free lobes to promote channel opening, a molecular implementation of a logical NOR operation that processes spatiotemporal Ca2+ signals bifurcated by CaM lobes. Overall, a unified scheme of CaV channel regulation by CaM now emerges, and our findings highlight the versatility of CaM to perform exquisite Ca2+ computations.
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25
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Villalobo A, Ishida H, Vogel HJ, Berchtold MW. Calmodulin as a protein linker and a regulator of adaptor/scaffold proteins. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1865:507-521. [PMID: 29247668 DOI: 10.1016/j.bbamcr.2017.12.004] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 12/07/2017] [Accepted: 12/08/2017] [Indexed: 01/29/2023]
Abstract
Calmodulin (CaM) is a universal regulator for a huge number of proteins in all eukaryotic cells. Best known is its function as a calcium-dependent modulator of the activity of enzymes, such as protein kinases and phosphatases, as well as other signaling proteins including membrane receptors, channels and structural proteins. However, less well known is the fact that CaM can also function as a Ca2+-dependent adaptor protein, either by bridging between different domains of the same protein or by linking two identical or different target proteins together. These activities are possible due to the fact that CaM contains two independently-folded Ca2+ binding lobes that are able to interact differentially and to some degree separately with targets proteins. In addition, CaM can interact with and regulates several proteins that function exclusively as adaptors. This review provides an overview over our present knowledge concerning the structural and functional aspects of the role of CaM as an adaptor protein and as a regulator of known adaptor/scaffold proteins.
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Affiliation(s)
- Antonio Villalobo
- Department of Cancer Biology, Instituto de Investigaciones Biomédicas, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Arturo Duperier 4, E-28029 Madrid, Spain.
| | - Hiroaki Ishida
- Department of Biological Sciences, University of Calgary, 2500 University Dr. N.W., Calgary, Alberta T2N 1N4, Canada
| | - Hans J Vogel
- Department of Biological Sciences, University of Calgary, 2500 University Dr. N.W., Calgary, Alberta T2N 1N4, Canada.
| | - Martin W Berchtold
- Department of Biology, University of Copenhagen, 13 Universitetsparken, DK-2100 Copenhagen Ø, Denmark.
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Chemin J, Taiakina V, Monteil A, Piazza M, Guan W, Stephens RF, Kitmitto A, Pang ZP, Dolphin AC, Perez-Reyes E, Dieckmann T, Guillemette JG, Spafford JD. Calmodulin regulates Ca v3 T-type channels at their gating brake. J Biol Chem 2017; 292:20010-20031. [PMID: 28972185 PMCID: PMC5723990 DOI: 10.1074/jbc.m117.807925] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 09/19/2017] [Indexed: 01/10/2023] Open
Abstract
Calcium (Cav1 and Cav2) and sodium channels possess homologous CaM-binding motifs, known as IQ motifs in their C termini, which associate with calmodulin (CaM), a universal calcium sensor. Cav3 T-type channels, which serve as pacemakers of the mammalian brain and heart, lack a C-terminal IQ motif. We illustrate that T-type channels associate with CaM using co-immunoprecipitation experiments and single particle cryo-electron microscopy. We demonstrate that protostome invertebrate (LCav3) and human Cav3.1, Cav3.2, and Cav3.3 T-type channels specifically associate with CaM at helix 2 of the gating brake in the I-II linker of the channels. Isothermal titration calorimetry results revealed that the gating brake and CaM bind each other with high-nanomolar affinity. We show that the gating brake assumes a helical conformation upon binding CaM, with associated conformational changes to both CaM lobes as indicated by amide chemical shifts of the amino acids of CaM in 1H-15N HSQC NMR spectra. Intact Ca2+-binding sites on CaM and an intact gating brake sequence (first 39 amino acids of the I-II linker) were required in Cav3.2 channels to prevent the runaway gating phenotype, a hyperpolarizing shift in voltage sensitivities and faster gating kinetics. We conclude that the presence of high-nanomolar affinity binding sites for CaM at its universal gating brake and its unique form of regulation via the tuning of the voltage range of activity could influence the participation of Cav3 T-type channels in heart and brain rhythms. Our findings may have implications for arrhythmia disorders arising from mutations in the gating brake or CaM.
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Affiliation(s)
- Jean Chemin
- Institut de Génomique Fonctionnelle, CNRS, INSERM, Université de Montpellier, Montpellier F-34094, France
| | | | - Arnaud Monteil
- Institut de Génomique Fonctionnelle, CNRS, INSERM, Université de Montpellier, Montpellier F-34094, France
| | - Michael Piazza
- Departments of Chemistry, Waterloo, Ontario N2L 3G1, Canada
| | - Wendy Guan
- Biology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | | | - Ashraf Kitmitto
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9NT, United Kingdom
| | - Zhiping P Pang
- Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey 08901
| | - Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom
| | - Edward Perez-Reyes
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908
| | | | | | - J David Spafford
- Biology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
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27
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Chyan CL, Irene D, Lin SM. The Recognition of Calmodulin to the Target Sequence of Calcineurin-A Novel Binding Mode. Molecules 2017; 22:E1584. [PMID: 28934144 PMCID: PMC6151454 DOI: 10.3390/molecules22101584] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 09/18/2017] [Accepted: 09/18/2017] [Indexed: 11/22/2022] Open
Abstract
Calcineurin (CaN) is a Ca2+/calmodulin-dependent Ser/Thr protein phosphatase, which plays essential roles in many cellular and developmental processes. CaN comprises two subunits, a catalytic subunit (CaN-A, 60 kDa) and a regulatory subunit (CaN-B, 19 kDa). CaN-A tightly binds to CaN-B in the presence of minimal levels of Ca2+, but the enzyme is inactive until activated by CaM. Upon binding to CaM, CaN then undergoes a conformational rearrangement, the auto inhibitory domain is displaced and thus allows for full activity. In order to elucidate the regulatory role of CaM in the activation processes of CaN, we used NMR spectroscopy to determine the structure of the complex of CaM and the target peptide of CaN (CaNp). The CaM/CaNp complex shows a compact ellipsoidal shape with 8 α-helices of CaM wrapping around the CaNp helix. The RMSD of backbone and heavy atoms of twenty lowest energy structures of CaM/CaNp complex are 0.66 and 1.14 Å, respectively. The structure of CaM/CaNp complex can be classified as a novel binding mode family 1-18 with major anchor residues Ile396 and Leu413 to allocate the largest space between two domains of CaM. The relative orientation of CaNp to CaM is similar to the CaMKK peptide in the 1-16 binding mode with N- and C-terminal hydrophobic anchors of target sequence engulfed in the hydrophobic pockets of the N- and C-domain of CaM, respectively. In the light of the structural model of CaM/CaNp complex reported here, we provide new insight in the activation processes of CaN by CaM. We propose that the hydrophobic interactions between the Ca2+-saturated C-domain and C-terminal half of the target sequence provide driving forces for the initial recognition. Subsequent folding in the target sequence and structural readjustments in CaM enhance the formation of the complex and affinity to calcium. The electrostatic repulsion between CaM/CaNp complex and AID may result in the displacement of AID from active site for full activity.
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Affiliation(s)
- Chia-Lin Chyan
- Department of Chemistry, National Dong Hwa University, Hualien 974, Taiwan.
| | - Deli Irene
- Department of Chemistry, National Dong Hwa University, Hualien 974, Taiwan.
| | - Sin-Mao Lin
- Department of Chemistry, National Dong Hwa University, Hualien 974, Taiwan.
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Chi CH, Tang CY, Pan CY. Calmodulin modulates the Ca 2+-dependent inactivation and expression level of bovine Ca V2.2 expressed in HEK293T cells. IBRO Rep 2017; 2:63-71. [PMID: 30135934 PMCID: PMC6084911 DOI: 10.1016/j.ibror.2017.03.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 02/27/2017] [Accepted: 03/10/2017] [Indexed: 01/31/2023] Open
Abstract
Ca2+ influx through voltage-gated Ca2+ channels (CaVs) at the plasma membrane is the major pathway responsible for the elevation of the intracellular Ca2+ concentration ([Ca2+]i), which activates various physiological activities. Calmodulin (CaM) is known to be involved in the Ca2+-dependent inactivation (CDI) of several types of CaVs; however, little is known about how CaM modulates CaV2.2. Here, we expressed CaV2.2 with CaM or CaM mutants with a Ca2+-binding deficiency in HEK293T cells and measured the currents to characterize the CDI. The results showed that CaV2.2 displayed a fast inactivation with Ca2+ but not Ba2+ as the charge carrier; when CaV2.2 was co-expressed with CaM mutants with a Ca2+-binding deficiency, the level of inactivation decreased. Using glutathione S-transferase-tagged CaM or CaM mutants as the bait, we found that CaM could interact with the intracellular C-terminal fragment of CaV2.2 in the presence or absence of Ca2+. However, CaM and its mutants could not interact with this fragment when mutations were generated in the conserved amino acid residues of the CaM-binding site. CaV2.2 with mutations in the CaM-binding site showed a greatly reduced current that could be rescued by CaM12 (Ca2+-binding deficiency at the N-lobe) overexpression; in addition, CaM12 enhanced the total expression level of CaV2.2, but the ratio of CaV2.2 present in the membrane to the total fraction remained unchanged. Together, our data suggest that CaM, with different Ca2+-binding abilities, modulates not only the inactivation of CaV2.2 but also its expression to regulate Ca2+-related physiological activities.
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Affiliation(s)
- Chih-Hung Chi
- Department of Life Science, National Taiwan University, Taipei, Taiwan
| | - Chih-Yung Tang
- Department of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan.,Graduate Institute of Brain and Mind Sciences, National Taiwan University, Taipei, Taiwan
| | - Chien-Yuan Pan
- Department of Life Science, National Taiwan University, Taipei, Taiwan.,Graduate Institute of Brain and Mind Sciences, National Taiwan University, Taipei, Taiwan
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Li C, Lim S, Braunewell KH, Ames JB. Structure and Calcium Binding Properties of a Neuronal Calcium-Myristoyl Switch Protein, Visinin-Like Protein 3. PLoS One 2016; 11:e0165921. [PMID: 27820860 PMCID: PMC5098827 DOI: 10.1371/journal.pone.0165921] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 10/19/2016] [Indexed: 12/13/2022] Open
Abstract
Visinin-like protein 3 (VILIP-3) belongs to a family of Ca2+-myristoyl switch proteins that regulate signal transduction in the brain and retina. Here we analyze Ca2+ binding, characterize Ca2+-induced conformational changes, and determine the NMR structure of myristoylated VILIP-3. Three Ca2+ bind cooperatively to VILIP-3 at EF2, EF3 and EF4 (KD = 0.52 μM and Hill slope of 1.8). NMR assignments, mutagenesis and structural analysis indicate that the covalently attached myristoyl group is solvent exposed in Ca2+-bound VILIP-3, whereas Ca2+-free VILIP-3 contains a sequestered myristoyl group that interacts with protein residues (E26, Y64, V68), which are distinct from myristate contacts seen in other Ca2+-myristoyl switch proteins. The myristoyl group in VILIP-3 forms an unusual L-shaped structure that places the C14 methyl group inside a shallow protein groove, in contrast to the much deeper myristoyl binding pockets observed for recoverin, NCS-1 and GCAP1. Thus, the myristoylated VILIP-3 protein structure determined in this study is quite different from those of other known myristoyl switch proteins (recoverin, NCS-1, and GCAP1). We propose that myristoylation serves to fine tune the three-dimensional structures of neuronal calcium sensor proteins as a means of generating functional diversity.
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Affiliation(s)
- Congmin Li
- Department of Chemistry, University of California Davis, Davis, CA, United States of America
| | - Sunghyuk Lim
- Department of Chemistry, University of California Davis, Davis, CA, United States of America
| | - Karl H. Braunewell
- Department of Neurophysiology, Medical Faculty, Ruhr University Bochum, Bochum, Germany
| | - James B. Ames
- Department of Chemistry, University of California Davis, Davis, CA, United States of America
- * E-mail:
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Benmocha Guggenheimer A, Almagor L, Tsemakhovich V, Tripathy DR, Hirsch JA, Dascal N. Interactions between N and C termini of α1C subunit regulate inactivation of CaV1.2 L-type Ca(2+) channel. Channels (Austin) 2016; 10:55-68. [PMID: 26577286 DOI: 10.1080/19336950.2015.1108499] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
The modulation and regulation of voltage-gated Ca(2+) channels is affected by the pore-forming segments, the cytosolic parts of the channel, and interacting intracellular proteins. In this study we demonstrate a direct physical interaction between the N terminus (NT) and C terminus (CT) of the main subunit of the L-type Ca(2+) channel CaV1.2, α1C, and explore the importance of this interaction for the regulation of the channel. We used biochemistry to measure the strength of the interaction and to map the location of the interaction sites, and electrophysiology to investigate the functional impact of the interaction. We show that the full-length NT (amino acids 1-154) and the proximal (close to the plasma membrane) part of the CT, pCT (amino acids 1508-1669) interact with sub-micromolar to low-micromolar affinity. Calmodulin (CaM) is not essential for the binding. The results further suggest that the NT-CT interaction regulates the channel's inactivation, and that Ca(2+), presumably through binding to calmodulin (CaM), reduces the strength of NT-CT interaction. We propose a molecular mechanism in which NT and CT of the channel serve as levers whose movements regulate inactivation by promoting changes in the transmembrane core of the channel via S1 (NT) or S6 (pCT) segments of domains I and IV, accordingly, and not as a kind of pore blocker. We hypothesize that Ca(2+)-CaM-induced changes in NT-CT interaction may, in part, underlie the acceleration of CaV1.2 inactivation induced by Ca(2+) entry into the cell.
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Affiliation(s)
- Adva Benmocha Guggenheimer
- a Department of Physiology and Pharmacology ; Sackler School of Medicine; Sagol School of Neuroscience ; Tel Aviv , Israel
| | - Lior Almagor
- b Department of Biochemistry & Molecular Biology ; Institute of Structural Biology, George S Weiss Faculty of Life Sciences; Sagol School of Neuroscience; Tel Aviv University ; Tel Aviv , Israel.,c Present address: Department of Structural Biology , Stanford University, School of Medicine ; Stanford , CA USA
| | - Vladimir Tsemakhovich
- a Department of Physiology and Pharmacology ; Sackler School of Medicine; Sagol School of Neuroscience ; Tel Aviv , Israel
| | - Debi Ranjan Tripathy
- b Department of Biochemistry & Molecular Biology ; Institute of Structural Biology, George S Weiss Faculty of Life Sciences; Sagol School of Neuroscience; Tel Aviv University ; Tel Aviv , Israel
| | - Joel A Hirsch
- b Department of Biochemistry & Molecular Biology ; Institute of Structural Biology, George S Weiss Faculty of Life Sciences; Sagol School of Neuroscience; Tel Aviv University ; Tel Aviv , Israel
| | - Nathan Dascal
- a Department of Physiology and Pharmacology ; Sackler School of Medicine; Sagol School of Neuroscience ; Tel Aviv , Israel
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31
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Ben-Johny M, Dick IE, Sang L, Limpitikul WB, Kang PW, Niu J, Banerjee R, Yang W, Babich JS, Issa JB, Lee SR, Namkung H, Li J, Zhang M, Yang PS, Bazzazi H, Adams PJ, Joshi-Mukherjee R, Yue DN, Yue DT. Towards a Unified Theory of Calmodulin Regulation (Calmodulation) of Voltage-Gated Calcium and Sodium Channels. Curr Mol Pharmacol 2016; 8:188-205. [PMID: 25966688 DOI: 10.2174/1874467208666150507110359] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Revised: 01/29/2015] [Accepted: 04/20/2015] [Indexed: 12/13/2022]
Abstract
Voltage-gated Na and Ca(2+) channels represent two major ion channel families that enable myriad biological functions including the generation of action potentials and the coupling of electrical and chemical signaling in cells. Calmodulin regulation (calmodulation) of these ion channels comprises a vital feedback mechanism with distinct physiological implications. Though long-sought, a shared understanding of the channel families remained elusive for two decades as the functional manifestations and the structural underpinnings of this modulation often appeared to diverge. Here, we review recent advancements in the understanding of calmodulation of Ca(2+) and Na channels that suggest a remarkable similarity in their regulatory scheme. This interrelation between the two channel families now paves the way towards a unified mechanistic framework to understand vital calmodulin-dependent feedback and offers shared principles to approach related channelopathic diseases. An exciting era of synergistic study now looms.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - David T Yue
- Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Ross Building, Room 713, 720 Rutland Avenue, Baltimore, MD 21205, USA.
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32
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DeFalco TA, Marshall CB, Munro K, Kang HG, Moeder W, Ikura M, Snedden WA, Yoshioka K. Multiple Calmodulin-Binding Sites Positively and Negatively Regulate Arabidopsis CYCLIC NUCLEOTIDE-GATED CHANNEL12. THE PLANT CELL 2016; 28:1738-51. [PMID: 27335451 PMCID: PMC4981125 DOI: 10.1105/tpc.15.00870] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 06/08/2016] [Accepted: 06/21/2016] [Indexed: 05/18/2023]
Abstract
Ca(2+) signaling is critical to plant immunity; however, the channels involved are poorly characterized. Cyclic nucleotide-gated channels (CNGCs) are nonspecific, Ca(2+)-permeable cation channels. Plant CNGCs are hypothesized to be negatively regulated by the Ca(2+) sensor calmodulin (CaM), and previous work has focused on a C-terminal CaM-binding domain (CaMBD) overlapping with the cyclic nucleotide binding domain of plant CNGCs. However, we show that the Arabidopsis thaliana isoform CNGC12 possesses multiple CaMBDs at cytosolic N and C termini, which is reminiscent of animal CNGCs and unlike any plant channel studied to date. Biophysical characterizations of these sites suggest that apoCaM interacts with a conserved isoleucine-glutamine (IQ) motif in the C terminus of the channel, while Ca(2+)/CaM binds additional N- and C-terminal motifs with different affinities. Expression of CNGC12 with a nonfunctional N-terminal CaMBD constitutively induced programmed cell death, providing in planta evidence of allosteric CNGC regulation by CaM. Furthermore, we determined that CaM binding to the IQ motif was required for channel function, indicating that CaM can both positively and negatively regulate CNGC12. These data indicate a complex mode of plant CNGC regulation by CaM, in contrast to the previously proposed competitive ligand model, and suggest exciting parallels between plant and animal channels.
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Affiliation(s)
- Thomas A DeFalco
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3B2, Canada
| | - Christopher B Marshall
- Department of Medical Biophysics, Campbell Family Cancer Research Institute/Princess Margaret Cancer Centre, University of Toronto, Toronto, Ontario M5G 2M9, Canada
| | - Kim Munro
- Protein Function Discovery Facility, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Hong-Gu Kang
- Department of Biology, Texas State University, San Marcos, Texas 78666
| | - Wolfgang Moeder
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3B2, Canada
| | - Mitsuhiko Ikura
- Department of Medical Biophysics, Campbell Family Cancer Research Institute/Princess Margaret Cancer Centre, University of Toronto, Toronto, Ontario M5G 2M9, Canada
| | - Wayne A Snedden
- Department of Biology, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Keiko Yoshioka
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3B2, Canada Center for the Analysis of Genome Evolution and Function (CAGEF), University of Toronto, Toronto, Ontario M5S 3B2, Canada
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Regulation of GAP43/calmodulin complex formation via calcineurin-dependent mechanism in differentiated PC12 cells with altered PMCA isoforms composition. Mol Cell Biochem 2015; 407:251-62. [PMID: 26045175 PMCID: PMC4536269 DOI: 10.1007/s11010-015-2473-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 05/30/2015] [Indexed: 12/21/2022]
Abstract
Several lines of evidence suggest the contribution of age-related decline in plasma membrane calcium pump (PMCA) to the onset of neurodegenerative diseases. From four PMCA isoforms, PMCA2, and PMCA3 respond to a rapid removal of Ca2+ and are expressed predominantly in excitable cells. We have previously shown that suppression of neuron-specific PMCAs in differentiated PC12 cells accelerated cell differentiation, but increased apoptosis in PMCA2-deficient line. We also demonstrated that altered expression of voltage-dependent calcium channels correlated with their higher contribution to Ca2+ influx, which varied between PMCA-reduced lines. Here, we propose a mechanism unique for differentiated PC12 cells by which PMCA2 and PMCA3 regulate pGAP43/GAP43 ratio and the interaction between GAP43 and calmodulin (CaM). Although down-regulation of PMCA2 or PMCA3 altered the content of GAP43/pGAP43, of paramount importance for the regulatory mechanism is a disruption of isoform-specific inhibitory PMCA/calcineurin interaction. In result, higher endogenous calcineurin (CaN) activity leads to hypophosphorylation of GAP43 in PMCA2- or PMCA3-deficient lines and intensification of GAP43/CaM complex formation, thus potentially limiting the availability of free CaM. In overall, our results indicate that both “fast” PMCA isoforms could actively regulate the local CaN function and CaN-downstream processes. In connection with our previous observations, we also suggest a negative feedback of cooperative action of CaM, GAP43, and CaN on P/Q and L-type channels activity. PMCAs- and CaN-dependent mechanism presented here, may signify a protective action against calcium overload in neuronal cells during aging, as well a potential way for decreasing neuronal cells vulnerability to neurodegenerative insults.
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Ben-Johny M, Yue DT. Calmodulin regulation (calmodulation) of voltage-gated calcium channels. ACTA ACUST UNITED AC 2014; 143:679-92. [PMID: 24863929 PMCID: PMC4035741 DOI: 10.1085/jgp.201311153] [Citation(s) in RCA: 147] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Calmodulin regulation (calmodulation) of the family of voltage-gated CaV1-2 channels comprises a prominent prototype for ion channel regulation, remarkable for its powerful Ca(2+) sensing capabilities, deep in elegant mechanistic lessons, and rich in biological and therapeutic implications. This field thereby resides squarely at the epicenter of Ca(2+) signaling biology, ion channel biophysics, and therapeutic advance. This review summarizes the historical development of ideas in this field, the scope and richly patterned organization of Ca(2+) feedback behaviors encompassed by this system, and the long-standing challenges and recent developments in discerning a molecular basis for calmodulation. We conclude by highlighting the considerable synergy between mechanism, biological insight, and promising therapeutics.
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Affiliation(s)
- Manu Ben-Johny
- Calcium Signals Laboratory, Department of Biomedical Engineering, Department of Neuroscience, and Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205Calcium Signals Laboratory, Department of Biomedical Engineering, Department of Neuroscience, and Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205Calcium Signals Laboratory, Department of Biomedical Engineering, Department of Neuroscience, and Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205Calcium Signals Laboratory, Department of Biomedical Engineering, Department of Neuroscience, and Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - David T Yue
- Calcium Signals Laboratory, Department of Biomedical Engineering, Department of Neuroscience, and Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205Calcium Signals Laboratory, Department of Biomedical Engineering, Department of Neuroscience, and Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205Calcium Signals Laboratory, Department of Biomedical Engineering, Department of Neuroscience, and Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205Calcium Signals Laboratory, Department of Biomedical Engineering, Department of Neuroscience, and Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205
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35
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Two domains of the smoothelin-like 1 protein bind apo- and calcium–calmodulin independently. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2014; 1844:1580-90. [DOI: 10.1016/j.bbapap.2014.05.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 05/14/2014] [Accepted: 05/24/2014] [Indexed: 12/24/2022]
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36
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Wafer LN, Tzul FO, Pandharipande PP, McCallum SA, Makhatadze GI. Structural and thermodynamic characterization of the recognition of the S100-binding peptides TRTK12 and p53 by calmodulin. Protein Sci 2014; 23:1247-61. [PMID: 24947426 DOI: 10.1002/pro.2506] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Revised: 06/14/2014] [Accepted: 06/17/2014] [Indexed: 11/07/2022]
Abstract
Calmodulin (CaM) is a multifunctional messenger protein that activates a wide variety of signaling pathways in eukaryotic cells in a calcium-dependent manner. CaM has been proposed to be functionally distinct from the S100 proteins, a related family of eukaryotic calcium-binding proteins. Previously, it was demonstrated that peptides derived from the actin-capping protein, TRTK12, and the tumor-suppressor protein, p53, interact with multiple members of the S100 proteins. To test the specificity of these peptides, they were screened using isothermal titration calorimetry against 16 members of the human S100 protein family, as well as CaM, which served as a negative control. Interestingly, both the TRTK12 and p53 peptides were found to interact with CaM. These interactions were further confirmed by both fluorescence and nuclear magnetic resonance spectroscopies. These peptides have distinct sequences from the known CaM target sequences. The TRTK12 peptide was found to independently interact with both CaM domains and bind with a stoichiometry of 2:1 and dissociations constants Kd,C-term = 2 ± 1 µM and Kd,N-term = 14 ± 1 µM. In contrast, the p53 peptide was found to interact only with the C-terminal domain of CaM, Kd,C-term = 2 ± 1 µM, 25°C. Using NMR spectroscopy, the locations of the peptide binding sites were mapped onto the structure of CaM. The binding sites for both peptides were found to overlap with the binding interface for previously identified targets on both domains of CaM. This study demonstrates the plasticity of CaM in target binding and may suggest a possible overlap in target specificity between CaM and the S100 proteins.
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Affiliation(s)
- Lucas N Wafer
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, New York, 12180; Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York, 12180
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37
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The Ever Changing Moods of Calmodulin: How Structural Plasticity Entails Transductional Adaptability. J Mol Biol 2014; 426:2717-35. [DOI: 10.1016/j.jmb.2014.05.016] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 05/14/2014] [Accepted: 05/16/2014] [Indexed: 11/20/2022]
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38
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Mruk K, Farley BM, Ritacco AW, Kobertz WR. Calmodulation meta-analysis: predicting calmodulin binding via canonical motif clustering. J Gen Physiol 2014; 144:105-14. [PMID: 24935744 PMCID: PMC4076516 DOI: 10.1085/jgp.201311140] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 05/21/2014] [Indexed: 11/20/2022] Open
Abstract
The calcium-binding protein calmodulin (CaM) directly binds to membrane transport proteins to modulate their function in response to changes in intracellular calcium concentrations. Because CaM recognizes and binds to a wide variety of target sequences, identifying CaM-binding sites is difficult, requiring intensive sequence gazing and extensive biochemical analysis. Here, we describe a straightforward computational script that rapidly identifies canonical CaM-binding motifs within an amino acid sequence. Analysis of the target sequences from high resolution CaM-peptide structures using this script revealed that CaM often binds to sequences that have multiple overlapping canonical CaM-binding motifs. The addition of a positive charge discriminator to this meta-analysis resulted in a tool that identifies potential CaM-binding domains within a given sequence. To allow users to search for CaM-binding motifs within a protein of interest, perform the meta-analysis, and then compare the results to target peptide-CaM structures deposited in the Protein Data Bank, we created a website and online database. The availability of these tools and analyses will facilitate the design of CaM-related studies of ion channels and membrane transport proteins.
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Affiliation(s)
- Karen Mruk
- Department of Biochemistry and Molecular Pharmacology and Programs in Chemical Biology and Neuroscience, and
| | - Brian M Farley
- Department of Biochemistry and Molecular Pharmacology and Programs in Chemical Biology and Neuroscience, and
| | - Alan W Ritacco
- Department of Scientific and Research Computing, University of Massachusetts Medical School, Worcester, MA 01605
| | - William R Kobertz
- Department of Biochemistry and Molecular Pharmacology and Programs in Chemical Biology and Neuroscience, and
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Simms BA, Zamponi GW. Neuronal voltage-gated calcium channels: structure, function, and dysfunction. Neuron 2014; 82:24-45. [PMID: 24698266 DOI: 10.1016/j.neuron.2014.03.016] [Citation(s) in RCA: 420] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Voltage-gated calcium channels are the primary mediators of depolarization-induced calcium entry into neurons. There is great diversity of calcium channel subtypes due to multiple genes that encode calcium channel α1 subunits, coassembly with a variety of ancillary calcium channel subunits, and alternative splicing. This allows these channels to fulfill highly specialized roles in specific neuronal subtypes and at particular subcellular loci. While calcium channels are of critical importance to brain function, their inappropriate expression or dysfunction gives rise to a variety of neurological disorders, including, pain, epilepsy, migraine, and ataxia. This Review discusses salient aspects of voltage-gated calcium channel function, physiology, and pathophysiology.
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Affiliation(s)
- Brett A Simms
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Gerald W Zamponi
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada.
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Simms BA, Souza IA, Zamponi GW. A novel calmodulin site in the Cav1.2 N-terminus regulates calcium-dependent inactivation. Pflugers Arch 2013; 466:1793-803. [DOI: 10.1007/s00424-013-1423-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Revised: 12/05/2013] [Accepted: 12/06/2013] [Indexed: 01/04/2023]
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Sorensen AB, Søndergaard MT, Overgaard MT. Calmodulin in a Heartbeat. FEBS J 2013; 280:5511-32. [DOI: 10.1111/febs.12337] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Revised: 04/28/2013] [Accepted: 05/07/2013] [Indexed: 01/16/2023]
Affiliation(s)
- Anders B. Sorensen
- Department of Biotechnology, Chemistry and Environmental Engineering; Aalborg University; Denmark
| | - Mads T. Søndergaard
- Department of Biotechnology, Chemistry and Environmental Engineering; Aalborg University; Denmark
| | - Michael T. Overgaard
- Department of Biotechnology, Chemistry and Environmental Engineering; Aalborg University; Denmark
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Taiakina V, Boone AN, Fux J, Senatore A, Weber-Adrian D, Guillemette JG, Spafford JD. The calmodulin-binding, short linear motif, NSCaTE is conserved in L-type channel ancestors of vertebrate Cav1.2 and Cav1.3 channels. PLoS One 2013; 8:e61765. [PMID: 23626724 PMCID: PMC3634016 DOI: 10.1371/journal.pone.0061765] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Accepted: 03/11/2013] [Indexed: 01/21/2023] Open
Abstract
NSCaTE is a short linear motif of (xWxxx(I or L)xxxx), composed of residues with a high helix-forming propensity within a mostly disordered N-terminus that is conserved in L-type calcium channels from protostome invertebrates to humans. NSCaTE is an optional, lower affinity and calcium-sensitive binding site for calmodulin (CaM) which competes for CaM binding with a more ancient, C-terminal IQ domain on L-type channels. CaM bound to N- and C- terminal tails serve as dual detectors to changing intracellular Ca2+ concentrations, promoting calcium-dependent inactivation of L-type calcium channels. NSCaTE is absent in some arthropod species, and is also lacking in vertebrate L-type isoforms, Cav1.1 and Cav1.4 channels. The pervasiveness of a methionine just downstream from NSCaTE suggests that L-type channels could generate alternative N-termini lacking NSCaTE through the choice of translational start sites. Long N-terminus with an NSCaTE motif in L-type calcium channel homolog LCav1 from pond snail Lymnaea stagnalis has a faster calcium-dependent inactivation than a shortened N-termini lacking NSCaTE. NSCaTE effects are present in low concentrations of internal buffer (0.5 mM EGTA), but disappears in high buffer conditions (10 mM EGTA). Snail and mammalian NSCaTE have an alpha-helical propensity upon binding Ca2+-CaM and can saturate both CaM N-terminal and C-terminal domains in the absence of a competing IQ motif. NSCaTE evolved in ancestors of the first animals with internal organs for promoting a more rapid, calcium-sensitive inactivation of L-type channels.
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Affiliation(s)
| | | | - Julia Fux
- Department of Biology, University of Waterloo, Waterloo, Canada
| | | | | | | | - J. David Spafford
- Department of Biology, University of Waterloo, Waterloo, Canada
- * E-mail:
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Kovalevskaya NV, van de Waterbeemd M, Bokhovchuk FM, Bate N, Bindels RJM, Hoenderop JGJ, Vuister GW. Structural analysis of calmodulin binding to ion channels demonstrates the role of its plasticity in regulation. Pflugers Arch 2013; 465:1507-19. [PMID: 23609407 DOI: 10.1007/s00424-013-1278-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 03/18/2013] [Accepted: 04/02/2013] [Indexed: 12/17/2022]
Abstract
The Ca²⁺-binding protein calmodulin (CaM) is a well-known regulator of ion-channel activity. Consequently, the Protein Data Bank contains many structures of CaM in complex with different fragments of ion channels that together display a variety of binding modes. In addition to the canonical interaction, in which CaM engages its target with both its domains, many of the ion-channel-CaM complexes demonstrate alternative non-canonical binding modes that depend on the target and experimental conditions. Based on these findings, several mechanisms of ion-channel regulation by CaM have been proposed, all exploiting its plasticity and flexibility in interacting with its targets. In this review, we focus on complexes of CaM with either the voltage-gated calcium channels; the voltage-gated sodium channels or the small conductance calcium-activated potassium channels, for which both structural and functional data are available. For each channel, the functional relevance of these structural data and possible mechanism of calcium-dependent (in)activation and/or facilitation are discussed in detail.
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Affiliation(s)
- Nadezda V Kovalevskaya
- Department of Physiology, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Geert Grooteplein Zuid 26-28, Nijmegen, 6525, GA, The Netherlands
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Marbella LE, Cho HS, Spence MM. Observing the translocation of a mitochondria-penetrating peptide with solid-state NMR. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:1674-82. [PMID: 23567916 DOI: 10.1016/j.bbamem.2013.03.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2013] [Revised: 03/25/2013] [Accepted: 03/29/2013] [Indexed: 12/18/2022]
Abstract
A new class of penetrating peptides that can target the mitochondria with high specificity was recently discovered. In this work, we developed a model inner mitochondrial membrane, equipped with a transmembrane gradient, suitable for solid-state NMR experiments. Using solid-state NMR, we observed a mitochondria-penetrating peptide interacting with the model inner mitochondrial membrane to gain insight into the mechanism of translocation. The paramagnetic relaxation effect due to Mn(2+) ions on (13)C magic angle spinning NMR was used to measure the insertion depth of the peptide and its distribution in each monolayer of the membrane. We found that at low peptide concentration the peptide binds to the outer leaflet and at high concentration, it crosses the hydrophobic bilayer core and is distributed in both leaflets. In both concentration regimes, the peptide binds at the C2 position on the lipid acyl chain. The mitochondria-penetrating peptide crossed to the inner leaflet of the model membranes without disrupting the lamellarity. These results provide evidence that supports the electroporation model of translocation. We estimated the energy associated with crossing the inner mitochondrial membrane. We found that the transmembrane potential provides sufficient energy for the peptide to cross the hydrophobic core, which is the most unfavorable step in translocation.
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Affiliation(s)
- Lauren E Marbella
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA.
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Ben Johny M, Yang PS, Bazzazi H, Yue DT. Dynamic switching of calmodulin interactions underlies Ca2+ regulation of CaV1.3 channels. Nat Commun 2013; 4:1717. [PMID: 23591884 PMCID: PMC3856249 DOI: 10.1038/ncomms2727] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 03/08/2013] [Indexed: 11/30/2022] Open
Abstract
Calmodulin regulation of CaV channels is a prominent Ca(2+) feedback mechanism orchestrating vital adjustments of Ca(2+) entry. The long-held structural correlation of this regulation has been Ca(2+)-bound calmodulin, complexed alone with an IQ domain on the channel carboxy terminus. Here, however, systematic alanine mutagenesis of the entire carboxyl tail of an L-type CaV1.3 channel casts doubt on this paradigm. To identify the actual molecular states underlying channel regulation, we develop a structure-function approach relating the strength of regulation to the affinity of underlying calmodulin/channel interactions, by a Langmuir relation (individually transformed Langmuir analysis). Accordingly, we uncover frank exchange of Ca(2+)-calmodulin to interfaces beyond the IQ domain, initiating substantial rearrangements of the calmodulin/channel complex. The N-lobe of Ca(2+)-calmodulin binds an N-terminal spatial Ca(2+) transforming element module on the channel amino terminus, whereas the C-lobe binds an EF-hand region upstream of the IQ domain. This system of structural plasticity furnishes a next-generation blueprint for CaV channel modulation.
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Affiliation(s)
- Manu Ben Johny
- Calcium Signals Laboratory, Departments of Biomedical Engineering and Neuroscience, The Johns Hopkins University School of Medicine, Ross Building, Room 713, 720 Rutland Avenue, Baltimore, MD 21205, voice: (410) 955-0078, fax: (410) 614-8269,
| | - Philemon S. Yang
- Calcium Signals Laboratory, Departments of Biomedical Engineering and Neuroscience, The Johns Hopkins University School of Medicine, Ross Building, Room 713, 720 Rutland Avenue, Baltimore, MD 21205, voice: (410) 955-0078, fax: (410) 614-8269,
| | - Hojjat Bazzazi
- Calcium Signals Laboratory, Departments of Biomedical Engineering and Neuroscience, The Johns Hopkins University School of Medicine, Ross Building, Room 713, 720 Rutland Avenue, Baltimore, MD 21205, voice: (410) 955-0078, fax: (410) 614-8269,
| | - David T. Yue
- Calcium Signals Laboratory, Departments of Biomedical Engineering and Neuroscience, The Johns Hopkins University School of Medicine, Ross Building, Room 713, 720 Rutland Avenue, Baltimore, MD 21205, voice: (410) 955-0078, fax: (410) 614-8269,
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Structural characterization of the interaction of human lactoferrin with calmodulin. PLoS One 2012; 7:e51026. [PMID: 23236421 PMCID: PMC3516504 DOI: 10.1371/journal.pone.0051026] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 10/29/2012] [Indexed: 12/21/2022] Open
Abstract
Lactoferrin (Lf) is an 80 kDa, iron (Fe3+)-binding immunoregulatory glycoprotein secreted into most exocrine fluids, found in high concentrations in colostrum and milk, and released from neutrophil secondary granules at sites of infection and inflammation. In a number of cell types, Lf is internalized through receptor-mediated endocytosis and targeted to the nucleus where it has been demonstrated to act as a transcriptional trans-activator. Here we characterize human Lf’s interaction with calmodulin (CaM), a ubiquitous, 17 kDa regulatory calcium (Ca2+)-binding protein localized in the cytoplasm and nucleus of activated cells. Due to the size of this intermolecular complex (∼100 kDa), TROSY-based NMR techniques were employed to structurally characterize Ca2+-CaM when bound to intact apo-Lf. Both CaM’s backbone amides and the ε-methyl group of key methionine residues were used as probes in chemical shift perturbation and cross-saturation experiments to define the binding interface of apo-Lf on Ca2+-CaM. Unlike the collapsed conformation through which Ca2+-CaM binds the CaM-binding domains of its classical targets, Ca2+-CaM assumes an extended structure when bound to apo-Lf. Apo-Lf appears to interact predominantly with the C-terminal lobe of Ca2+-CaM, enabling the N-terminal lobe to potentially bind another target. Our use of intact apo-Lf has made possible the identification of a secondary interaction interface, removed from CaM’s primary binding domain. Secondary interfaces play a key role in the target’s response to CaM binding, highlighting the importance of studying intact complexes. This solution-based approach can be applied to study other regulatory calcium-binding EF-hand proteins in intact intermolecular complexes.
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McCue HV, Patel P, Herbert AP, Lian LY, Burgoyne RD, Haynes LP. Solution NMR structure of the Ca2+-bound N-terminal domain of CaBP7: a regulator of golgi trafficking. J Biol Chem 2012; 287:38231-43. [PMID: 22989873 PMCID: PMC3488092 DOI: 10.1074/jbc.m112.402289] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 09/12/2012] [Indexed: 12/12/2022] Open
Abstract
Calcium-binding protein 7 (CaBP7) is a member of the calmodulin (CaM) superfamily that harbors two high affinity EF-hand motifs and a C-terminal transmembrane domain. CaBP7 has been previously shown to interact with and modulate phosphatidylinositol 4-kinase III-β (PI4KIIIβ) activity in in vitro assays and affects vesicle transport in neurons when overexpressed. Here we show that the N-terminal domain (NTD) of CaBP7 is sufficient to mediate the interaction of CaBP7 with PI4KIIIβ. CaBP7 NTD encompasses the two high affinity Ca(2+) binding sites, and structural characterization through multiangle light scattering, circular dichroism, and NMR reveals unique properties for this domain. CaBP7 NTD binds specifically to Ca(2+) but not Mg(2+) and undergoes significant conformational changes in both secondary and tertiary structure upon Ca(2+) binding. The Ca(2+)-bound form of CaBP7 NTD is monomeric and exhibits an open conformation similar to that of CaM. Ca(2+)-bound CaBP7 NTD has a solvent-exposed hydrophobic surface that is more expansive than observed in CaM or CaBP1. Within this hydrophobic pocket, there is a significant reduction in the number of methionine residues that are conserved in CaM and CaBP1 and shown to be important for target recognition. In CaBP7 NTD, these residues are replaced with isoleucine and leucine residues with branched side chains that are intrinsically more rigid than the flexible methionine side chain. We propose that these differences in surface hydrophobicity, charge, and methionine content may be important in determining highly specific interactions of CaBP7 with target proteins, such as PI4KIIIβ.
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Affiliation(s)
- Hannah V. McCue
- From the Physiological Laboratory, Department of Cellular and Molecular Physiology, Institute of Translational Medicine, and
| | - Pryank Patel
- From the Physiological Laboratory, Department of Cellular and Molecular Physiology, Institute of Translational Medicine, and
| | - Andrew P. Herbert
- From the Physiological Laboratory, Department of Cellular and Molecular Physiology, Institute of Translational Medicine, and
| | - Lu-Yun Lian
- the NMR Centre for Structural Biology, Institute of Integrative Biology, University of Liverpool, Liverpool L69 3BX, United Kingdom
| | - Robert D. Burgoyne
- From the Physiological Laboratory, Department of Cellular and Molecular Physiology, Institute of Translational Medicine, and
| | - Lee P. Haynes
- From the Physiological Laboratory, Department of Cellular and Molecular Physiology, Institute of Translational Medicine, and
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