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Paula S, Floruta S, Pajazetovic K, Sobota S, Almahmodi D. The molecular determinants of calcium ATPase inhibition by curcuminoids. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2024; 1866:184367. [PMID: 38969202 DOI: 10.1016/j.bbamem.2024.184367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 06/04/2024] [Accepted: 07/01/2024] [Indexed: 07/07/2024]
Abstract
The natural product curcumin and some of its analogs are known inhibitors of the transmembrane enzyme sarco/endoplasmic reticulum calcium ATPase (SERCA). Despite their widespread use, the curcuminoids' binding site in SERCA and their relevant interactions with the enzyme remain elusive. This lack of knowledge has prevented the development of curcuminoids into valuable experimental tools or into agents of therapeutic value. We used the crystal structures of SERCA in its E1 conformation in conjunction with computational tools such as docking and surface screens to determine the most likely curcumin binding site, along with key enzyme/inhibitor interactions. Additionally, we determined the inhibitory potencies and binding affinities for a small set of curcumin analogs. The predicted curcumin binding site is a narrow cleft in the transmembrane section of SERCA, close to the transmembrane/cytosol interface. In addition to pronounced complementarity in shape and hydrophobicity profiles between curcumin and the binding pocket, several hydrogen bonds were observed that were spread over the entire curcumin scaffold, involving residues on several transmembrane helices. Docking-predicted interactions were compatible with experimental observations for inhibitory potencies and binding affinities. Based on these findings, we propose an inhibition mechanism that assumes that the presence of a curcuminoid in the binding site arrests the catalytic cycle of SERCA by preventing it from converting from the E1 to the E2 conformation. This blockage of conformational change is accomplished by a combination of steric hinderance and hydrogen-bond-based cross-linking of transmembrane helices that require flexibility throughout the catalytic cycle.
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Affiliation(s)
- Stefan Paula
- Department of Chemistry, California State University Sacramento, 6000 J Street, Sacramento, CA 95819, USA.
| | - Sergiu Floruta
- Department of Chemistry, California State University Sacramento, 6000 J Street, Sacramento, CA 95819, USA
| | - Karim Pajazetovic
- Department of Chemistry, California State University Sacramento, 6000 J Street, Sacramento, CA 95819, USA
| | - Sydni Sobota
- Department of Chemistry, California State University Sacramento, 6000 J Street, Sacramento, CA 95819, USA
| | - Dina Almahmodi
- Department of Chemistry, California State University Sacramento, 6000 J Street, Sacramento, CA 95819, USA
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2
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Weber DK, Reddy UV, Robia SL, Veglia G. Pathological mutations in the phospholamban cytoplasmic region affect its topology and dynamics modulating the extent of SERCA inhibition. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2024; 1866:184370. [PMID: 38986894 PMCID: PMC11457527 DOI: 10.1016/j.bbamem.2024.184370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Revised: 06/26/2024] [Accepted: 07/02/2024] [Indexed: 07/12/2024]
Abstract
Phospholamban (PLN) is a 52 amino acid regulin that allosterically modulates the activity of the sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) in the heart muscle. In its unphosphorylated form, PLN binds SERCA within its transmembrane (TM) domains, approximately 20 Å away from the Ca2+ binding site, reducing SERCA's apparent Ca2+ affinity (pKCa) and decreasing cardiac contractility. During the enzymatic cycle, the inhibitory TM domain of PLN remains anchored to SERCA, whereas its cytoplasmic region transiently binds the ATPase's headpiece. Phosphorylation of PLN at Ser16 by protein kinase A increases the affinity of its cytoplasmic domain to SERCA, weakening the TM interactions with the ATPase, reversing its inhibitory function, and augmenting muscle contractility. How the structural changes caused by pathological mutations in the PLN cytoplasmic region are transmitted to its inhibitory TM domain is still unclear. Using solid-state NMR spectroscopy and activity assays, we analyzed the structural and functional effects of a series of mutations and their phosphorylated forms located in the PLN cytoplasmic region and linked to dilated cardiomyopathy. We found that these missense mutations affect the overall topology and dynamics of PLN and ultimately modulate its inhibitory potency. Also, the changes in the TM tilt angle and cytoplasmic dynamics of PLN caused by these mutations correlate well with the extent of SERCA inhibition. Our study unveils new molecular determinants for designing variants of PLN that outcompete endogenous PLN to regulate SERCA in a tunable manner.
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Affiliation(s)
- Daniel K Weber
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - U Venkateswara Reddy
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Seth L Robia
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL, USA
| | - Gianluigi Veglia
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.
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3
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Rathod N, Lemieux MJ, Chipot C, Roux B, Young HS. Probing the formation of a hetero-dimeric membrane transport complex with dual in vitro and in silico mutagenesis. Chem Sci 2024:d4sc02915a. [PMID: 39156929 PMCID: PMC11322925 DOI: 10.1039/d4sc02915a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2024] [Accepted: 08/05/2024] [Indexed: 08/20/2024] Open
Abstract
The reversible association of transmembrane helices is a fundamental mechanism in how living cells convey information and respond to physiological events. The cardiac calcium transport regulator phospholamban (PLN) is an example of a single-span transmembrane protein that populates a variety of reversible and competing oligomeric states. PLN primarily forms monomers and pentamers in the membrane, where the PLN pentamer is a storage form and the PLN monomer forms a hetero-dimeric inhibitory complex with SERCA. The binding affinity and free-energy of formation of the SERCA-PLN complex in a membrane have not been determined. As is the case for most transmembrane protein interactions, measuring these quantities experimentally is extremely challenging. In this study, we estimated binding affinities by employing in silico alchemical free-energy calculations for all PLN transmembrane alanine substitutions in a membrane bilayer. The binding affinities were calculated separately for the SERCA-PLN complex, a PLN monomer, and a PLN pentamer and compared to in vitro functional measurements of SERCA regulation by the PLN alanine substitutions. Initially, the changes in SERCA inhibition by PLN alanine substitutions were compared to the changes in free energy for the SERCA-PLN complex formed from the PLN monomer. However, the functional data for the PLN alanine substitutions were better explained by the formation of the SERCA-PLN complex directly from the PLN pentamer. This finding points to an inhibitory mechanism favoring conformational selection of SERCA and the interaction of a PLN pentamer with SERCA for 'delivery' of a PLN monomer to the inhibitory site. The implications of these findings suggest that the energetics of helix exchange between homo- and hetero-oligomeric signaling complexes is favored over an intermediate involving a free monomeric helix in the membrane bilayer.
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Affiliation(s)
- Nishadh Rathod
- Department of Biochemistry, University of Alberta Edmonton Alberta Canada T6G 2H7 +1 (780) 492-3931 +1 (780) 492-3931
| | - M Joanne Lemieux
- Department of Biochemistry, University of Alberta Edmonton Alberta Canada T6G 2H7 +1 (780) 492-3931 +1 (780) 492-3931
| | - Christophe Chipot
- Department of Biochemistry and Molecular Biology, University of Chicago Chicago USA 60637
- Laboratoire International Associé Centre National de la Recherche Scientifique et University of Illinois at Urbana-Champaign, Unité Mixte de Recherche no. 7019, Université de Lorraine B.P. 70239, 54506 Vandœuvre-lès-Nancy Cedex France
- Theoretical and Computational Biophysics Group, Beckman Institute, Department of Physics, University of Illinois at Urbana-Champaign Urbana Illinois 61801 USA
| | - Benoît Roux
- Department of Biochemistry and Molecular Biology, University of Chicago Chicago USA 60637
| | - Howard S Young
- Department of Biochemistry, University of Alberta Edmonton Alberta Canada T6G 2H7 +1 (780) 492-3931 +1 (780) 492-3931
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Cleary SR, Seflova J, Cho EE, Bisht K, Khandelia H, Espinoza-Fonseca LM, Robia SL. Phospholamban inhibits the cardiac calcium pump by interrupting an allosteric activation pathway. J Biol Chem 2024; 300:107267. [PMID: 38583863 PMCID: PMC11098958 DOI: 10.1016/j.jbc.2024.107267] [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: 09/07/2023] [Revised: 03/20/2024] [Accepted: 04/02/2024] [Indexed: 04/09/2024] Open
Abstract
Phospholamban (PLB) is a transmembrane micropeptide that regulates the sarcoplasmic reticulum Ca2+-ATPase (SERCA) in cardiac muscle, but the physical mechanism of this regulation remains poorly understood. PLB reduces the Ca2+ sensitivity of active SERCA, increasing the Ca2+ concentration required for pump cycling. However, PLB does not decrease Ca2+ binding to SERCA when ATP is absent, suggesting PLB does not inhibit SERCA Ca2+ affinity. The prevailing explanation for these seemingly conflicting results is that PLB slows transitions in the SERCA enzymatic cycle associated with Ca2+ binding, altering transport Ca2+ dependence without actually affecting the equilibrium binding affinity of the Ca2+-coordinating sites. Here, we consider another hypothesis, that measurements of Ca2+ binding in the absence of ATP overlook important allosteric effects of nucleotide binding that increase SERCA Ca2+ binding affinity. We speculated that PLB inhibits SERCA by reversing this allostery. To test this, we used a fluorescent SERCA biosensor to quantify the Ca2+ affinity of non-cycling SERCA in the presence and absence of a non-hydrolyzable ATP-analog, AMPPCP. Nucleotide activation increased SERCA Ca2+ affinity, and this effect was reversed by co-expression of PLB. Interestingly, PLB had no effect on Ca2+ affinity in the absence of nucleotide. These results reconcile the previous conflicting observations from ATPase assays versus Ca2+ binding assays. Moreover, structural analysis of SERCA revealed a novel allosteric pathway connecting the ATP- and Ca2+-binding sites. We propose this pathway is disrupted by PLB binding. Thus, PLB reduces the equilibrium Ca2+ affinity of SERCA by interrupting allosteric activation of the pump by ATP.
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Affiliation(s)
- Sean R Cleary
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - Jaroslava Seflova
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - Ellen E Cho
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - Konark Bisht
- Department of Physics, Chemistry, and Pharmacy, PHYLIFE: Physical Life Science, University of Southern Denmark, Odense, Denmark
| | - Himanshu Khandelia
- Department of Physics, Chemistry, and Pharmacy, PHYLIFE: Physical Life Science, University of Southern Denmark, Odense, Denmark
| | - L Michel Espinoza-Fonseca
- Division of Cardiovascular Medicine, Department of Internal Medicine, Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan, USA
| | - Seth L Robia
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA.
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Zeinert R, Zhou F, Franco P, Zöller J, Lessen HJ, Aravind L, Langer JD, Sodt AJ, Storz G, Matthies D. Magnesium Transporter MgtA revealed as a Dimeric P-type ATPase. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.28.582502. [PMID: 38464158 PMCID: PMC10925321 DOI: 10.1101/2024.02.28.582502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Magnesium (Mg2+) uptake systems are present in all domains of life given the vital role of this ion. Bacteria acquire Mg2+ via conserved Mg2+ channels and transporters. The transporters are required for growth when Mg2+ is limiting or during bacterial pathogenesis, but, despite their significance, there are no known structures for these transporters. Here we report the first structure of the Mg2+ transporter MgtA solved by single particle cryo-electron microscopy (cryo-EM). Using mild membrane extraction, we obtained high resolution structures of both a homodimeric form (2.9 Å), the first for a P-type ATPase, and a monomeric form (3.6 Å). Each monomer unit of MgtA displays a structural architecture that is similar to other P-type ATPases with a transmembrane domain and two soluble domains. The dimer interface consists of contacts between residues in adjacent soluble nucleotide binding and phosphotransfer regions of the haloacid dehalogenase (HAD) domain. We suggest oligomerization is a conserved structural feature of the diverse family of P-type ATPase transporters. The ATP binding site and conformational dynamics upon nucleotide binding to MgtA were characterized using a combination of cryo-EM, molecular dynamics simulations, hydrogen-deuterium exchange mass spectrometry, and mutagenesis. Our structure also revealed a Mg2+ ion in the transmembrane segments, which, when combined with sequence conservation and mutagenesis studies, allowed us to propose a model for Mg2+ transport across the lipid bilayer. Finally, our work revealed the N-terminal domain structure and cytoplasmic Mg2+ binding sites, which have implications for related P-type ATPases defective in human disease.
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Affiliation(s)
- Rilee Zeinert
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda MD 20892, USA
| | - Fei Zhou
- Unit on Structural Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda MD 20892, USA
| | - Pedro Franco
- Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Jonathan Zöller
- Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Henry J. Lessen
- Unit on Membrane Chemical Physics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda MD 20892, USA
| | - L. Aravind
- National Center for Biotechnology Information, National Institutes of Health, Bethesda MD 20892, USA
| | - Julian D. Langer
- Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Alexander J. Sodt
- Unit on Membrane Chemical Physics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda MD 20892, USA
| | - Gisela Storz
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda MD 20892, USA
| | - Doreen Matthies
- Unit on Structural Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda MD 20892, USA
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Rathod N, Guerrero-Serna G, Young HS, Espinoza-Fonseca LM. Replacement of Lys27 by asparagine in the SERCA regulator myoregulin: A Ca 2+ affinity modulator or a catalytic activity switch? BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119613. [PMID: 37918638 DOI: 10.1016/j.bbamcr.2023.119613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 09/06/2023] [Accepted: 10/16/2023] [Indexed: 11/04/2023]
Abstract
Myoregulin (MLN) is a protein that regulates the activity of the sarcoplasmic reticulum Ca2+-ATPase (SERCA) without affecting its affinity for Ca2+. MLN's residue Lys27 is located at a site where other SERCA regulators control Ca2+ affinity. Therefore, we conducted atomistic simulations and ATPase activity experiments to determine whether replacing Lys27 with asparagine, a conserved residue found in various muscle SERCA regulators, would enable MLN to modulate both the Ca2+ affinity and catalytic activity of SERCA. Our findings indicate that replacing Lys27 with Asn significantly enhances the inhibitory potency of MLN, but it does not affect SERCA's affinity for Ca2+. We suggest that the SERCA site modulating Ca2+ affinity also acts as a catalytic activity switch. Therefore, this site is a key element contributing to the functional divergence among homologous SERCA regulators. This study paves the way for future investigations to explore how biological function diverges during the evolution of the SERCA regulator family.
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Affiliation(s)
- Nishadh Rathod
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Guadalupe Guerrero-Serna
- Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Howard S Young
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - L Michel Espinoza-Fonseca
- Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, MI 48109, USA.
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7
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Šeflová J, Cruz-Cortés C, Guerrero-Serna G, Robia SL, Espinoza-Fonseca LM. Mechanisms for cardiac calcium pump activation by its substrate and a synthetic allosteric modulator using fluorescence lifetime imaging. PNAS NEXUS 2024; 3:pgad453. [PMID: 38222469 PMCID: PMC10785037 DOI: 10.1093/pnasnexus/pgad453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 12/15/2023] [Indexed: 01/16/2024]
Abstract
The discovery of allosteric modulators is an emerging paradigm in drug discovery, and signal transduction is a subtle and dynamic process that is challenging to characterize. We developed a time-correlated single photon-counting imaging approach to investigate the structural mechanisms for small-molecule activation of the cardiac sarcoplasmic reticulum Ca2+-ATPase, a pharmacologically important pump that transports Ca2+ at the expense of adenosine triphosphate (ATP) hydrolysis. We first tested whether the dissociation of sarcoplasmic reticulum Ca2+-ATPase from its regulatory protein phospholamban is required for small-molecule activation. We found that CDN1163, a validated sarcoplasmic reticulum Ca2+-ATPase activator, does not have significant effects on the stability of the sarcoplasmic reticulum Ca2+-ATPase-phospholamban complex. Time-correlated single photon-counting imaging experiments using the nonhydrolyzable ATP analog β,γ-Methyleneadenosine 5'-triphosphate (AMP-PCP) showed ATP is an allosteric modulator of sarcoplasmic reticulum Ca2+-ATPase, increasing the fraction of catalytically competent structures at physiologically relevant Ca2+ concentrations. Unlike ATP, CDN1163 alone has no significant effects on the Ca2+-dependent shifts in the structural populations of sarcoplasmic reticulum Ca2+-ATPase, and it does not increase the pump's affinity for Ca2+ ions. However, we found that CDN1163 enhances the ATP-mediated modulatory effects to increase the population of catalytically competent sarcoplasmic reticulum Ca2+-ATPase structures. Importantly, this structural shift occurs within the physiological window of Ca2+ concentrations at which sarcoplasmic reticulum Ca2+-ATPase operates. We demonstrated that ATP is both a substrate and modulator of sarcoplasmic reticulum Ca2+-ATPase and showed that CDN1163 and ATP act synergistically to populate sarcoplasmic reticulum Ca2+-ATPase structures that are primed for phosphorylation. This study provides novel insights into the structural mechanisms for sarcoplasmic reticulum Ca2+-ATPase activation by its substrate and a synthetic allosteric modulator.
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Affiliation(s)
- Jaroslava Šeflová
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL 60153, USA
| | - Carlos Cruz-Cortés
- Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Guadalupe Guerrero-Serna
- Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Seth L Robia
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL 60153, USA
| | - L Michel Espinoza-Fonseca
- Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, MI 48109, USA
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Zádor E. The Meeting of Micropeptides with Major Ca 2+ Pumps in Inner Membranes-Consideration of a New Player, SERCA1b. MEMBRANES 2023; 13:274. [PMID: 36984661 PMCID: PMC10058886 DOI: 10.3390/membranes13030274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 02/20/2023] [Accepted: 02/23/2023] [Indexed: 06/18/2023]
Abstract
Calcium is a major signalling bivalent cation within the cell. Compartmentalization is essential for regulation of calcium mediated processes. A number of players contribute to intracellular handling of calcium, among them are the sarco/endoplasmic reticulum calcium ATP-ases (SERCAs). These molecules function in the membrane of ER/SR pumping Ca2+ from cytoplasm into the lumen of the internal store. Removal of calcium from the cytoplasm is essential for signalling and for relaxation of skeletal muscle and heart. There are three genes and over a dozen isoforms of SERCA in mammals. These can be potentially influenced by small membrane peptides, also called regulins. The discovery of micropeptides has increased in recent years, mostly because of the small ORFs found in long RNAs, annotated formerly as noncoding (lncRNAs). Several excellent works have analysed the mechanism of interaction of micropeptides with each other and with the best known SERCA1a (fast muscle) and SERCA2a (heart, slow muscle) isoforms. However, the array of tissue and developmental expressions of these potential regulators raises the question of interaction with other SERCAs. For example, the most abundant calcium pump in neonatal and regenerating skeletal muscle, SERCA1b has never been looked at with scrutiny to determine whether it is influenced by micropeptides. Further details might be interesting on the interaction of these peptides with the less studied SERCA1b isoform.
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Affiliation(s)
- Ernő Zádor
- Institute of Biochemistry, Albert Szent-Györgyi Faculty of Medicine, University of Szeged, Dóm tér 9, H-6720 Szeged, Hungary
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Phillips TA, Hauck GT, Pribadi MP, Cho EE, Cleary SR, Robia SL. Micropeptide hetero-oligomerization adds complexity to the calcium pump regulatory network. Biophys J 2023; 122:301-309. [PMID: 36523160 PMCID: PMC9892615 DOI: 10.1016/j.bpj.2022.12.014] [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: 05/20/2022] [Revised: 10/24/2022] [Accepted: 12/09/2022] [Indexed: 12/16/2022] Open
Abstract
The sarco(endo)plasmic reticulum calcium ATPase (SERCA) is an ion transporter that creates and maintains intracellular calcium stores. SERCA is inhibited or stimulated by several membrane micropeptides including another-regulin, dwarf open reading frame, endoregulin, phospholamban (PLB), and sarcolipin. We previously showed that these micropeptides assemble into homo-oligomeric complexes with varying affinity. Here, we tested whether different micropeptides can interact with each other, hypothesizing that coassembly into hetero-oligomers may affect micropeptide bioavailability to regulate SERCA. We quantified the relative binding affinity of each combination of candidates using automated fluorescence resonance energy transfer microscopy. All pairs were capable of interacting with good affinity, similar to the affinity of micropeptide self-binding (homo-oligomerization). Testing each pair at a 1:5 ratio and a reciprocal 5:1 ratio, we noted that the affinity of hetero-oligomerization of some micropeptides depended on whether they were the minority or majority species. In particular, sarcolipin was able to join oligomers when it was the minority species but did not readily accommodate other micropeptides in the reciprocal experiment when it was expressed in fivefold excess. The opposite was observed for endoregulin. PLB was a universal partner for all other micropeptides tested, forming avid hetero-oligomers whether it was the minority or majority species. Increasing expression of SERCA decreased PLB-dwarf open reading frame hetero-oligomerization, suggesting that SERCA-micropeptide interactions compete with micropeptide-micropeptide interactions. Thus, micropeptides populate a regulatory network of diverse protein assemblies. The data suggest that the complexity of this interactome increases exponentially with the number of micropeptides that are coexpressed in a particular tissue.
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Affiliation(s)
- Taylor A Phillips
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois
| | - Garrett T Hauck
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois
| | - Marsha P Pribadi
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois
| | - Ellen E Cho
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois
| | - Sean R Cleary
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois
| | - Seth L Robia
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois.
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Funk F, Kronenbitter A, Isić M, Flocke V, Gorreßen S, Semmler D, Brinkmann M, Beck K, Steinhoff O, Srivastava T, Barbosa DM, Voigt K, Wang L, Bottermann K, Kötter S, Grandoch M, Flögel U, Krüger M, Schmitt JP. Diabetes disturbs functional adaptation of the remote myocardium after ischemia/reperfusion. J Mol Cell Cardiol 2022; 173:47-60. [PMID: 36150524 DOI: 10.1016/j.yjmcc.2022.09.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 07/01/2022] [Accepted: 09/16/2022] [Indexed: 01/06/2023]
Abstract
Diabetes mellitus type 2 is associated with adverse clinical outcome after myocardial infarction. To better understand the underlying causes we here investigated sarcomere protein function and its calcium-dependent regulation in the non-ischemic remote myocardium (RM) of diabetic mice (db/db) after transient occlusion of the left anterior descending coronary artery. Before and 24 h after surgery db/db and non-diabetic db/+ underwent magnetic resonance imaging followed by histological and biochemical analyses of heart tissue. Intracellular calcium transients and sarcomere function were measured in isolated cardiomyocytes. Active and passive force generation was assessed in skinned fibers and papillary muscle preparations. Before ischemia and reperfusion (I/R), beat-to-beat calcium cycling was depressed in diabetic cardiomyocytes. Nevertheless, contractile function was preserved owing to increased myofilament calcium sensitivity and higher responsiveness of myocardial force production to β-adrenergic stimulation in db/db compared to db/+. In addition, protein kinase C activity was elevated in db/db hearts leading to strong phosphorylation of the titin PEVK region and increased titin-based tension of myofilaments. I/R impaired the function of whole hearts and RM sarcomeres in db/db to a larger extent than in non-diabetic db/+, and we identified several reasons. First, the amplitude and the kinetics of cardiomyocyte calcium transients were further reduced in the RM of db/db. Underlying causes involved altered expression of calcium regulatory proteins. Diabetes and I/R additively reduced phospholamban S16-phosphorylation by 80% (P < 000.1) leading to strong inhibition of the calcium ATPase SERCA2a. Second, titin stiffening was only observed in the RM of db/+, but not in the RM of db/db. Finally, db/db myofilament calcium sensitivity and force generation upon β-adrenergic stimulation were no longer enhanced over db/+ in the RM. The findings demonstrate that impaired cardiomyocyte calcium cycling of db/db hearts is compensated by increased myofilament calcium sensitivity and increased titin-based stiffness prior to I/R. In contrast, sarcomere function of the RM 24 h after I/R is poor because both these compensatory mechanisms fail and myocyte calcium handling is further depressed.
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Affiliation(s)
- Florian Funk
- Institute of Pharmacology, University Hospital Düsseldorf, and Cardiovascular Research Institute Düsseldorf (CARID), Universitätsstraße 1, 40225 Düsseldorf, Germany.
| | - Annette Kronenbitter
- Institute of Pharmacology, University Hospital Düsseldorf, and Cardiovascular Research Institute Düsseldorf (CARID), Universitätsstraße 1, 40225 Düsseldorf, Germany
| | - Malgorzata Isić
- Institute of Cardiovascular Physiology, University Hospital Düsseldorf, and Cardiovascular Research Institute Düsseldorf (CARID), Universitätsstraße 1, 40225 Düsseldorf, Germany
| | - Vera Flocke
- Institute of Molecular Cardiology, Heinrich-Heine-University, Universitätsstraße 1, 40225 Düsseldorf, Germany.
| | - Simone Gorreßen
- Institute of Pharmacology, University Hospital Düsseldorf, and Cardiovascular Research Institute Düsseldorf (CARID), Universitätsstraße 1, 40225 Düsseldorf, Germany.
| | - Dominik Semmler
- Institute of Pharmacology, University Hospital Düsseldorf, and Cardiovascular Research Institute Düsseldorf (CARID), Universitätsstraße 1, 40225 Düsseldorf, Germany.
| | - Maximilian Brinkmann
- Institute of Pharmacology, University Hospital Düsseldorf, and Cardiovascular Research Institute Düsseldorf (CARID), Universitätsstraße 1, 40225 Düsseldorf, Germany.
| | - Katharina Beck
- Institute of Pharmacology, University Hospital Düsseldorf, and Cardiovascular Research Institute Düsseldorf (CARID), Universitätsstraße 1, 40225 Düsseldorf, Germany.
| | - Oliver Steinhoff
- Institute of Translational Pharmacology, University Hospital Düsseldorf, and Cardiovascular Research Institute Düsseldorf (CARID), Universitätsstraße 1, 40225 Düsseldorf, Germany.
| | - Tanu Srivastava
- Institute of Pharmacology, University Hospital Düsseldorf, and Cardiovascular Research Institute Düsseldorf (CARID), Universitätsstraße 1, 40225 Düsseldorf, Germany.
| | - David Monteiro Barbosa
- Institute of Cardiovascular Physiology, University Hospital Düsseldorf, and Cardiovascular Research Institute Düsseldorf (CARID), Universitätsstraße 1, 40225 Düsseldorf, Germany
| | - Katharina Voigt
- Institute of Cardiovascular Physiology, University Hospital Düsseldorf, and Cardiovascular Research Institute Düsseldorf (CARID), Universitätsstraße 1, 40225 Düsseldorf, Germany.
| | - Luzhou Wang
- Institute of Pharmacology, University Hospital Düsseldorf, and Cardiovascular Research Institute Düsseldorf (CARID), Universitätsstraße 1, 40225 Düsseldorf, Germany.
| | - Katharina Bottermann
- Institute of Pharmacology, University Hospital Düsseldorf, and Cardiovascular Research Institute Düsseldorf (CARID), Universitätsstraße 1, 40225 Düsseldorf, Germany.
| | - Sebastian Kötter
- Institute of Cardiovascular Physiology, University Hospital Düsseldorf, and Cardiovascular Research Institute Düsseldorf (CARID), Universitätsstraße 1, 40225 Düsseldorf, Germany.
| | - Maria Grandoch
- Institute of Translational Pharmacology, University Hospital Düsseldorf, and Cardiovascular Research Institute Düsseldorf (CARID), Universitätsstraße 1, 40225 Düsseldorf, Germany.
| | - Ulrich Flögel
- Institute of Molecular Cardiology, Heinrich-Heine-University, Universitätsstraße 1, 40225 Düsseldorf, Germany.
| | - Martina Krüger
- Institute of Cardiovascular Physiology, University Hospital Düsseldorf, and Cardiovascular Research Institute Düsseldorf (CARID), Universitätsstraße 1, 40225 Düsseldorf, Germany.
| | - Joachim P Schmitt
- Institute of Pharmacology, University Hospital Düsseldorf, and Cardiovascular Research Institute Düsseldorf (CARID), Universitätsstraße 1, 40225 Düsseldorf, Germany.
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11
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Foster DB, Gu JM, Kim EH, Wolfson DW, O’Meally R, Cole RN, Cho HC. Tbx18 Orchestrates Cytostructural Transdifferentiation of Cardiomyocytes to Pacemaker Cells by Recruiting the Epithelial-Mesenchymal Transition Program. J Proteome Res 2022; 21:2277-2292. [PMID: 36006872 PMCID: PMC9552783 DOI: 10.1021/acs.jproteome.2c00133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Indexed: 11/29/2022]
Abstract
Previously, we reported that heterologous expression of an embryonic transcription factor, Tbx18, reprograms ventricular cardiomyocytes into induced pacemaker cells (Tbx18-iPMs), though the key pathways are unknown. Here, we have used a tandem mass tag proteomic approach to characterize the impact of Tbx18 on neonatal rat ventricular myocytes. Tbx18 expression triggered vast proteome remodeling. Tbx18-iPMs exhibited increased expression of known pacemaker ion channels, including Hcn4 and Cx45 as well as upregulation of the mechanosensitive ion channels Piezo1, Trpp2 (PKD2), and TrpM7. Metabolic pathways were broadly downregulated, as were ion channels associated with ventricular excitation-contraction coupling. Tbx18-iPMs also exhibited extensive intracellular cytoskeletal and extracellular matrix remodeling, including 96 differentially expressed proteins associated with the epithelial-to-mesenchymal transition (EMT). RNAseq extended coverage of low abundance transcription factors, revealing upregulation of EMT-inducing Snai1, Snai2, Twist1, Twist2, and Zeb2. Finally, network diffusion mapping of >200 transcriptional regulators indicates EMT and heart development factors occupy adjacent network neighborhoods downstream of Tbx18 but upstream of metabolic control factors. In conclusion, transdifferentiation of cardiac myocytes into pacemaker cells entails massive electrogenic, metabolic, and cytostructural remodeling. Structural changes exhibit hallmarks of the EMT. The results aid ongoing efforts to maximize the yield and phenotypic stability of engineered biological pacemakers.
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Affiliation(s)
- D. Brian Foster
- Division
of Cardiology, Department of Medicine, The
Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, United States
| | - Jin-mo Gu
- Department
of Pediatrics, Emory University, Atlanta, Georgia 30322, United States
| | - Elizabeth H. Kim
- Cedars-Sinai
Medical Center, Los Angeles, California 90048, United States
| | - David W. Wolfson
- Wallace
H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia 30332, United States
| | - Robert O’Meally
- Proteomics
Core Facility, The Johns Hopkins University
School of Medicine, Baltimore, Maryland 21205, United States
| | - Robert N. Cole
- Proteomics
Core Facility, The Johns Hopkins University
School of Medicine, Baltimore, Maryland 21205, United States
| | - Hee Cheol Cho
- Department
of Surgery, The Johns Hopkins University
School of Medicine, Baltimore, Maryland 21205, United States
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12
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Crosstalk between Glycogen-Selective Autophagy, Autophagy and Apoptosis as a Road towards Modifier Gene Discovery and New Therapeutic Strategies for Glycogen Storage Diseases. Life (Basel) 2022; 12:life12091396. [PMID: 36143432 PMCID: PMC9504455 DOI: 10.3390/life12091396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Revised: 08/23/2022] [Accepted: 09/01/2022] [Indexed: 11/30/2022] Open
Abstract
Glycogen storage diseases (GSDs) are rare metabolic monogenic disorders characterized by an excessive accumulation of glycogen in the cell. However, monogenic disorders are not simple regarding genotype–phenotype correlation. Genes outside the major disease-causing locus could have modulatory effect on GSDs, and thus explain the genotype–phenotype inconsistencies observed in these patients. Nowadays, when the sequencing of all clinically relevant genes, whole human exomes, and even whole human genomes is fast, easily available and affordable, we have a scientific obligation to holistically analyze data and draw smarter connections between genotype and phenotype. Recently, the importance of glycogen-selective autophagy for the pathophysiology of disorders of glycogen metabolism have been described. Therefore, in this manuscript, we review the potential role of genes involved in glycogen-selective autophagy as modifiers of GSDs. Given the small number of genes associated with glycogen-selective autophagy, we also include genes, transcription factors, and non-coding RNAs involved in autophagy. A cross-link with apoptosis is addressed. All these genes could be analyzed in GSD patients with unusual discrepancies between genotype and phenotype in order to discover genetic variants potentially modifying their phenotype. The discovery of modifier genes related to glycogen-selective autophagy and autophagy will start a new chapter in understanding of GSDs and enable the usage of autophagy-inducing drugs for the treatment of this group of rare-disease patients.
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13
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Bak JJ, Aguayo-Ortiz R, Rathod N, Primeau JO, Khan MB, Robia SL, Lemieux MJ, Espinoza-Fonseca LM, Young HS. Primitive Phospholamban- and Sarcolipin-like Peptides Inhibit the Sarcoplasmic Reticulum Calcium Pump SERCA. Biochemistry 2022; 61:1419-1430. [PMID: 35771007 PMCID: PMC10588654 DOI: 10.1021/acs.biochem.2c00246] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Intracellular calcium signaling is essential for all kingdoms of life. An important part of this process is the sarco-endoplasmic reticulum Ca2+-ATPase (SERCA), which maintains the low cytosolic calcium levels required for intracellular calcium homeostasis. In higher organisms, SERCA is regulated by a series of tissue-specific transmembrane subunits such as phospholamban in cardiac muscles and sarcolipin in skeletal muscles. These regulatory axes are so important for muscle contractility that SERCA, phospholamban, and sarcolipin are practically invariant across mammalian species. With the recent discovery of the arthropod sarcolambans, the family of calcium pump regulatory subunits appears to span more than 550 million years of evolutionary divergence from arthropods to humans. This evolutionary divergence is reflected in the peptide sequences, which vary enormously from one another and only vaguely resemble phospholamban and sarcolipin. The discovery of the sarcolambans allowed us to address two questions. How much sequence variation is tolerated in the regulation of mammalian SERCA activity by the transmembrane peptides? Do divergent peptide sequences mimic phospholamban or sarcolipin in their regulatory activities despite limited sequence similarity? We expressed and purified recombinant sarcolamban peptides from three different arthropods. The peptides were coreconstituted into proteoliposomes with mammalian SERCA1a and the effect of each peptide on the apparent calcium affinity and maximal activity of SERCA was measured. All three peptides were superinhibitors of SERCA, exhibiting either phospholamban-like or sarcolipin-like characteristics. Molecular modeling, protein-protein docking, and molecular dynamics simulations revealed novel features of the divergent peptides and their SERCA regulatory properties.
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Affiliation(s)
- Jessi J. Bak
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
| | - Rodrigo Aguayo-Ortiz
- Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Nishadh Rathod
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
| | - Joseph O. Primeau
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
| | - Muhammad Bashir Khan
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
| | - Seth L. Robia
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL 60153, USA
| | - M. Joanne Lemieux
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
| | - L. Michel Espinoza-Fonseca
- Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Howard S. Young
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
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14
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Luraghi A, Ferrandi M, Barassi P, Arici M, Hsu SC, Torre E, Ronchi C, Romerio A, Chang GJ, Ferrari P, Bianchi G, Zaza A, Rocchetti M, Peri F. Highly Selective SERCA2a Activators: Preclinical Development of a Congeneric Group of First-in-Class Drug Leads against Heart Failure. J Med Chem 2022; 65:7324-7333. [PMID: 35580334 PMCID: PMC9150102 DOI: 10.1021/acs.jmedchem.2c00347] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Indexed: 11/30/2022]
Abstract
The stimulation of sarcoplasmic reticulum calcium ATPase SERCA2a emerged as a novel therapeutic strategy to efficiently improve overall cardiac function in heart failure (HF) with reduced arrhythmogenic risk. Istaroxime is a clinical-phase IIb compound with a double mechanism of action, Na+/K+ ATPase inhibition and SERCA2a stimulation. Starting from the observation that istaroxime metabolite PST3093 does not inhibit Na+/K+ ATPase while stimulates SERCA2a, we synthesized a series of bioisosteric PST3093 analogues devoid of Na+/K+ ATPase inhibitory activity. Most of them retained SERCA2a stimulatory action with nanomolar potency in cardiac preparations from healthy guinea pigs and streptozotocin (STZ)-treated rats. One compound was further characterized in isolated cardiomyocytes, confirming SERCA2a stimulation and in vivo showing a safety profile and improvement of cardiac performance following acute infusion in STZ rats. We identified a new class of selective SERCA2a activators as first-in-class drug candidates for HF treatment.
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Affiliation(s)
- Andrea Luraghi
- Department
of Biotechnology and Biosciences, University
of Milano-Bicocca, Milano 20126, Italy
| | - Mara Ferrandi
- Windtree
Therapeutics Inc., Warrington, Pennsylvania 18976, United States
| | - Paolo Barassi
- Windtree
Therapeutics Inc., Warrington, Pennsylvania 18976, United States
| | - Martina Arici
- Department
of Biotechnology and Biosciences, University
of Milano-Bicocca, Milano 20126, Italy
| | | | - Eleonora Torre
- Department
of Biotechnology and Biosciences, University
of Milano-Bicocca, Milano 20126, Italy
| | - Carlotta Ronchi
- Department
of Biotechnology and Biosciences, University
of Milano-Bicocca, Milano 20126, Italy
| | - Alessio Romerio
- Department
of Biotechnology and Biosciences, University
of Milano-Bicocca, Milano 20126, Italy
| | - Gwo-Jyh Chang
- Cardiovascular
Medicine, Chang Gung University, Tao-Yuan 333323 Taiwan
| | - Patrizia Ferrari
- Windtree
Therapeutics Inc., Warrington, Pennsylvania 18976, United States
| | - Giuseppe Bianchi
- Windtree
Therapeutics Inc., Warrington, Pennsylvania 18976, United States
- Università
Vita-Salute San Raffaele, Milano 20132, Italy
| | - Antonio Zaza
- Department
of Biotechnology and Biosciences, University
of Milano-Bicocca, Milano 20126, Italy
| | - Marcella Rocchetti
- Department
of Biotechnology and Biosciences, University
of Milano-Bicocca, Milano 20126, Italy
| | - Francesco Peri
- Department
of Biotechnology and Biosciences, University
of Milano-Bicocca, Milano 20126, Italy
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15
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Zhang Y, Inaba K. Structural basis of the conformational and functional regulation of human SERCA2b, the ubiquitous endoplasmic reticulum calcium pump. Bioessays 2022; 44:e2200052. [PMID: 35560336 DOI: 10.1002/bies.202200052] [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: 03/06/2022] [Revised: 04/29/2022] [Accepted: 04/29/2022] [Indexed: 11/06/2022]
Abstract
Sarco/endoplasmic reticulum Ca2+ ATPase 2b (SERCA2b), a member of the SERCA family, is expressed ubiquitously and transports Ca2+ into the sarco/endoplasmic reticulum using the energy provided by ATP binding and hydrolysis. The crystal structure of SERCA2b in its Ca2+ - and ATP-bound (E1∙2Ca2+ -ATP) state and cryo-electron microscopy (cryo-EM) structures of the protein in its E1∙2Ca2+ -ATP and Ca2+ -unbound phosphorylated (E2P) states have provided essential insights into how the overall conformation and ATPase activity of SERCA2b is regulated by the transmembrane helix 11 and the subsequent luminal extension loop, both of which are specific to this isoform. More recently, our cryo-EM analysis has revealed that SERCA2b likely adopts open and closed conformations of the cytosolic domains in the Ca2+ -bound but ATP-free (E1∙2Ca2+ ) state, and that the closed conformation represents a state immediately prior to ATP binding. This review article summarizes the unique mechanisms underlying the conformational and functional regulation of SERCA2b.
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Affiliation(s)
- Yuxia Zhang
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi, Japan
| | - Kenji Inaba
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi, Japan.,Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Miyagi, Japan.,Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi, Japan.,Core Research for Evolutional Science and Technology (CREST), Japan Agency for Medical Research and Development (AMED), Japan
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16
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Reddy UV, Weber DK, Wang S, Larsen EK, Gopinath T, De Simone A, Robia S, Veglia G. A kink in DWORF helical structure controls the activation of the sarcoplasmic reticulum Ca 2+-ATPase. Structure 2022; 30:360-370.e6. [PMID: 34875216 PMCID: PMC8897251 DOI: 10.1016/j.str.2021.11.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 09/14/2021] [Accepted: 11/11/2021] [Indexed: 12/31/2022]
Abstract
SERCA is a P-type ATPase embedded in the sarcoplasmic reticulum and plays a central role in muscle relaxation. SERCA's function is regulated by single-pass membrane proteins called regulins. Unlike other regulins, dwarf open reading frame (DWORF) expressed in cardiac muscle has a unique activating effect. Here, we determine the structure and topology of DWORF in lipid bilayers using a combination of oriented sample solid-state NMR spectroscopy and replica-averaged orientationally restrained molecular dynamics. We found that DWORF's structural topology consists of a dynamic N-terminal domain, an amphipathic juxtamembrane helix that crosses the lipid groups at an angle of 64°, and a transmembrane C-terminal helix with an angle of 32°. A kink induced by Pro15, unique to DWORF, separates the two helical domains. A single Pro15Ala mutant significantly decreases the kink and eliminates DWORF's activating effect on SERCA. Overall, our findings directly link DWORF's structural topology to its activating effect on SERCA.
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Affiliation(s)
- U. Venkateswara Reddy
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Daniel K. Weber
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Songlin Wang
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Erik K. Larsen
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Tata Gopinath
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Alfonso De Simone
- Department of Life Sciences, Imperial College London, South Kensington, London, SW7 2AZ, UK,Department of Pharmacy, University of Naples “Federico II”, Naples, 80131, Italy
| | - Seth Robia
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL 60153, USA
| | - Gianluigi Veglia
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, 6-155 Jackson Hall, Minneapolis, MN 55455, USA; Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA.
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17
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Hostrup M, Onslev J. The beta 2 -adrenergic receptor - a re-emerging target to combat obesity and induce leanness? J Physiol 2021; 600:1209-1227. [PMID: 34676534 DOI: 10.1113/jp281819] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 10/12/2021] [Indexed: 12/25/2022] Open
Abstract
Treatment of obesity with repurposed or novel drugs is an expanding research field. One approach is to target beta2 -adrenergic receptors because they regulate the metabolism and phenotype of adipose and skeletal muscle tissue. Several observations support a role for the beta2 -adrenergic receptor in obesity. Specific human beta2 -adrenergic receptor polymorphisms are associated with body composition and obesity, for which the Gln27Glu polymorphism is associated with obesity, while the Arg16Gly polymorphism is associated with lean mass in men and the development of obesity in specific populations. Individuals with obesity also have lower abundance of beta2 -adrenergic receptors in adipose tissue and are less sensitive to catecholamines. In addition, studies in livestock and rodents demonstrate that selective beta2 -agonists induce a so-called 'repartitioning effect' characterized by muscle accretion and reduced fat deposition. In humans, beta2 -agonists dose-dependently increase resting metabolic rate by 10-50%. And like that observed in other mammals, only a few weeks of treatment with beta2 -agonists increases muscle mass and reduces fat mass in young healthy individuals. Beta2 -agonists also exert beneficial effects on body composition when used concomitantly with training and act additively to increase muscle strength and mass during periods with resistance training. Thus, the beta2 -adrenergic receptor seems like an attractive target in the development of anti-obesity drugs. However, future studies need to verify the long-term efficacy and safety of beta2 -agonists in individuals with obesity, particularly in those with comorbidities.
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Affiliation(s)
- Morten Hostrup
- Section of Integrative Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Johan Onslev
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
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18
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Zhang Y, Watanabe S, Tsutsumi A, Kadokura H, Kikkawa M, Inaba K. Cryo-EM analysis provides new mechanistic insight into ATP binding to Ca 2+ -ATPase SERCA2b. EMBO J 2021; 40:e108482. [PMID: 34459010 DOI: 10.15252/embj.2021108482] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 08/02/2021] [Accepted: 08/04/2021] [Indexed: 12/31/2022] Open
Abstract
Sarco/endoplasmic reticulum Ca2+ -ATPase (SERCA) 2b is a ubiquitous SERCA family member that conducts Ca2+ uptake from the cytosol to the ER. Herein, we present a 3.3 Å resolution cryo-electron microscopy (cryo-EM) structure of human SERCA2b in the E1·2Ca2+ state, revealing a new conformation for Ca2+ -bound SERCA2b with a much closer arrangement of cytosolic domains than in the previously reported crystal structure of Ca2+ -bound SERCA1a. Multiple conformations generated by 3D classification of cryo-EM maps reflect the intrinsically dynamic nature of the cytosolic domains in this state. Notably, ATP binding residues of SERCA2b in the E1·2Ca2+ state are located at similar positions to those in the E1·2Ca2+ -ATP state; hence, the cryo-EM structure likely represents a preformed state immediately prior to ATP binding. Consistently, a SERCA2b mutant with an interdomain disulfide bridge that locks the closed cytosolic domain arrangement displayed significant autophosphorylation activity in the presence of Ca2+ . We propose a novel mechanism of ATP binding to SERCA2b.
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Affiliation(s)
- Yuxia Zhang
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan
| | - Satoshi Watanabe
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan
| | - Akihisa Tsutsumi
- Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Hiroshi Kadokura
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan
| | - Masahide Kikkawa
- Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Kenji Inaba
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan
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19
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Nothing Regular about the Regulins: Distinct Functional Properties of SERCA Transmembrane Peptide Regulatory Subunits. Int J Mol Sci 2021; 22:ijms22168891. [PMID: 34445594 PMCID: PMC8396278 DOI: 10.3390/ijms22168891] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 08/10/2021] [Accepted: 08/12/2021] [Indexed: 12/11/2022] Open
Abstract
The sarco-endoplasmic reticulum calcium ATPase (SERCA) is responsible for maintaining calcium homeostasis in all eukaryotic cells by actively transporting calcium from the cytosol into the sarco-endoplasmic reticulum (SR/ER) lumen. Calcium is an important signaling ion, and the activity of SERCA is critical for a variety of cellular processes such as muscle contraction, neuronal activity, and energy metabolism. SERCA is regulated by several small transmembrane peptide subunits that are collectively known as the “regulins”. Phospholamban (PLN) and sarcolipin (SLN) are the original and most extensively studied members of the regulin family. PLN and SLN inhibit the calcium transport properties of SERCA and they are required for the proper functioning of cardiac and skeletal muscles, respectively. Myoregulin (MLN), dwarf open reading frame (DWORF), endoregulin (ELN), and another-regulin (ALN) are newly discovered tissue-specific regulators of SERCA. Herein, we compare the functional properties of the regulin family of SERCA transmembrane peptide subunits and consider their regulatory mechanisms in the context of the physiological and pathophysiological roles of these peptides. We present new functional data for human MLN, ELN, and ALN, demonstrating that they are inhibitors of SERCA with distinct functional consequences. Molecular modeling and molecular dynamics simulations of SERCA in complex with the transmembrane domains of MLN and ALN provide insights into how differential binding to the so-called inhibitory groove of SERCA—formed by transmembrane helices M2, M6, and M9—can result in distinct functional outcomes.
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20
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Fisher ME, Bovo E, Aguayo-Ortiz R, Cho EE, Pribadi MP, Dalton MP, Rathod N, Lemieux MJ, Espinoza-Fonseca LM, Robia SL, Zima AV, Young HS. Dwarf open reading frame (DWORF) is a direct activator of the sarcoplasmic reticulum calcium pump SERCA. eLife 2021; 10:65545. [PMID: 34075877 PMCID: PMC8203291 DOI: 10.7554/elife.65545] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 06/01/2021] [Indexed: 01/05/2023] Open
Abstract
The sarco-plasmic reticulum calcium pump (SERCA) plays a critical role in the contraction-relaxation cycle of muscle. In cardiac muscle, SERCA is regulated by the inhibitor phospholamban. A new regulator, dwarf open reading frame (DWORF), has been reported to displace phospholamban from SERCA. Here, we show that DWORF is a direct activator of SERCA, increasing its turnover rate in the absence of phospholamban. Measurement of in-cell calcium dynamics supports this observation and demonstrates that DWORF increases SERCA-dependent calcium reuptake. These functional observations reveal opposing effects of DWORF activation and phospholamban inhibition of SERCA. To gain mechanistic insight into SERCA activation, fluorescence resonance energy transfer experiments revealed that DWORF has a higher affinity for SERCA in the presence of calcium. Molecular modeling and molecular dynamics simulations provide a model for DWORF activation of SERCA, where DWORF modulates the membrane bilayer and stabilizes the conformations of SERCA that predominate during elevated cytosolic calcium.
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Affiliation(s)
- M'Lynn E Fisher
- Department of Biochemistry, University of Alberta, Edmonton, Canada
| | - Elisa Bovo
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, United States
| | - Rodrigo Aguayo-Ortiz
- Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, United States
| | - Ellen E Cho
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, United States
| | - Marsha P Pribadi
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, United States
| | - Michael P Dalton
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, United States
| | - Nishadh Rathod
- Department of Biochemistry, University of Alberta, Edmonton, Canada
| | - M Joanne Lemieux
- Department of Biochemistry, University of Alberta, Edmonton, Canada
| | - L Michel Espinoza-Fonseca
- Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, United States
| | - Seth L Robia
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, United States
| | - Aleksey V Zima
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, United States
| | - Howard S Young
- Department of Biochemistry, University of Alberta, Edmonton, Canada
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21
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Cross-Talk Between the Adenylyl Cyclase/cAMP Pathway and Ca 2+ Homeostasis. Rev Physiol Biochem Pharmacol 2021; 179:73-116. [PMID: 33398503 DOI: 10.1007/112_2020_55] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Cyclic AMP and Ca2+ are the first second or intracellular messengers identified, unveiling the cellular mechanisms activated by a plethora of extracellular signals, including hormones. Cyclic AMP generation is catalyzed by adenylyl cyclases (ACs), which convert ATP into cAMP and pyrophosphate. By the way, Ca2+, as energy, can neither be created nor be destroyed; Ca2+ can only be transported, from one compartment to another, or chelated by a variety of Ca2+-binding molecules. The fine regulation of cytosolic concentrations of cAMP and free Ca2+ is crucial in cell function and there is an intimate cross-talk between both messengers to fine-tune the cellular responses. Cancer is a multifactorial disease resulting from a combination of genetic and environmental factors. Frequent cases of cAMP and/or Ca2+ homeostasis remodeling have been described in cancer cells. In those tumoral cells, cAMP and Ca2+ signaling plays a crucial role in the development of hallmarks of cancer, including enhanced proliferation and migration, invasion, apoptosis resistance, or angiogenesis. This review summarizes the cross-talk between the ACs/cAMP and Ca2+ intracellular pathways with special attention to the functional and reciprocal regulation between Orai1 and AC8 in normal and cancer cells.
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22
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Weber DK, Reddy UV, Wang S, Larsen EK, Gopinath T, Gustavsson MB, Cornea RL, Thomas DD, De Simone A, Veglia G. Structural basis for allosteric control of the SERCA-Phospholamban membrane complex by Ca 2+ and phosphorylation. eLife 2021; 10:66226. [PMID: 33978571 PMCID: PMC8184213 DOI: 10.7554/elife.66226] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 05/10/2021] [Indexed: 01/26/2023] Open
Abstract
Phospholamban (PLN) is a mini-membrane protein that directly controls the cardiac Ca2+-transport response to β-adrenergic stimulation, thus modulating cardiac output during the fight-or-flight response. In the sarcoplasmic reticulum membrane, PLN binds to the sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA), keeping this enzyme's function within a narrow physiological window. PLN phosphorylation by cAMP-dependent protein kinase A or increase in Ca2+ concentration reverses the inhibitory effects through an unknown mechanism. Using oriented-sample solid-state NMR spectroscopy and replica-averaged NMR-restrained structural refinement, we reveal that phosphorylation of PLN's cytoplasmic regulatory domain signals the disruption of several inhibitory contacts at the transmembrane binding interface of the SERCA-PLN complex that are propagated to the enzyme's active site, augmenting Ca2+ transport. Our findings address long-standing questions about SERCA regulation, epitomizing a signal transduction mechanism operated by posttranslationally modified bitopic membrane proteins.
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Affiliation(s)
- Daniel K Weber
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, United States
| | - U Venkateswara Reddy
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, United States
| | - Songlin Wang
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, United States
| | - Erik K Larsen
- Department of Chemistry, University of Minnesota, Minneapolis, United States
| | - Tata Gopinath
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, United States
| | - Martin B Gustavsson
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, United States
| | - Razvan L Cornea
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, United States
| | - David D Thomas
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, United States
| | - Alfonso De Simone
- Department of Life Sciences, Imperial College London, South Kensington, London, United Kingdom.,Department of Pharmacy, University of Naples 'Federico II', Naples, Italy
| | - Gianluigi Veglia
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, United States.,Department of Chemistry, University of Minnesota, Minneapolis, United States
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23
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Staritzbichler R, Sarti E, Yaklich E, Aleksandrova A, Stamm M, Khafizov K, Forrest LR. Refining pairwise sequence alignments of membrane proteins by the incorporation of anchors. PLoS One 2021; 16:e0239881. [PMID: 33930031 PMCID: PMC8087094 DOI: 10.1371/journal.pone.0239881] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 04/15/2021] [Indexed: 01/08/2023] Open
Abstract
The alignment of primary sequences is a fundamental step in the analysis of protein structure, function, and evolution, and in the generation of homology-based models. Integral membrane proteins pose a significant challenge for such sequence alignment approaches, because their evolutionary relationships can be very remote, and because a high content of hydrophobic amino acids reduces their complexity. Frequently, biochemical or biophysical data is available that informs the optimum alignment, for example, indicating specific positions that share common functional or structural roles. Currently, if those positions are not correctly matched by a standard pairwise sequence alignment procedure, the incorporation of such information into the alignment is typically addressed in an ad hoc manner, with manual adjustments. However, such modifications are problematic because they reduce the robustness and reproducibility of the aligned regions either side of the newly matched positions. Previous studies have introduced restraints as a means to impose the matching of positions during sequence alignments, originally in the context of genome assembly. Here we introduce position restraints, or "anchors" as a feature in our alignment tool AlignMe, providing an aid to pairwise global sequence alignment of alpha-helical membrane proteins. Applying this approach to realistic scenarios involving distantly-related and low complexity sequences, we illustrate how the addition of anchors can be used to modify alignments, while still maintaining the reproducibility and rigor of the rest of the alignment. Anchored alignments can be generated using the online version of AlignMe available at www.bioinfo.mpg.de/AlignMe/.
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Affiliation(s)
- René Staritzbichler
- ProteinFormatics Group, Institute of Biophysics and Medical Physics, University of Leipzig, Leipzig, Germany
| | - Edoardo Sarti
- Computational Structural Biology Section, National Institutes of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States of America
- Laboratoire de Biologie Computationnelle et Quantitative, Institut de Biologie Paris Seine, Sorbonne Université, Paris, France
| | - Emily Yaklich
- Computational Structural Biology Section, National Institutes of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States of America
| | - Antoniya Aleksandrova
- Computational Structural Biology Section, National Institutes of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States of America
| | - Marcus Stamm
- Max Planck Institute of Biophysics, Frankfurt am Main, Germany
| | - Kamil Khafizov
- Moscow Institute of Physics and Technology, National Research University, Moscow, Russia
| | - Lucy R. Forrest
- Computational Structural Biology Section, National Institutes of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States of America
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24
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Gopinath T, Weber D, Wang S, Larsen E, Veglia G. Solid-State NMR of Membrane Proteins in Lipid Bilayers: To Spin or Not To Spin? Acc Chem Res 2021; 54:1430-1439. [PMID: 33655754 PMCID: PMC11457538 DOI: 10.1021/acs.accounts.0c00670] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Membrane proteins mediate a plethora of cellular functions and represent important targets for drug development. Unlike soluble proteins, membrane proteins require native-like environments to fold correctly and be active. Therefore, modern structural biology techniques have aimed to determine the structure and dynamics of these membrane proteins at physiological temperature and in liquid crystalline lipid bilayers. With the flourishing of new NMR methodologies and improvements in sample preparations, magic angle spinning (MAS) and oriented sample solid-state NMR (OS-ssNMR) spectroscopy of membrane proteins is experiencing a new renaissance. Born as antagonistic approaches, these techniques nowadays offer complementary information on the structural topology and dynamics of membrane proteins reconstituted in lipid membranes. By spinning biosolid samples at the magic angle (θ = 54.7°), MAS NMR experiments remove the intrinsic anisotropy of the NMR interactions, increasing spectral resolution. Internuclear spin interactions (spin exchange) are reintroduced by RF pulses, providing distances and torsion angles to determine secondary, tertiary, and quaternary structures of membrane proteins. OS-ssNMR, on the other hand, directly detects anisotropic NMR parameters such as dipolar couplings (DC) and anisotropic chemical shifts (CS), providing orientational constraints to determine the architecture (i.e., topology) of membrane proteins relative to the lipid membrane. Defining the orientation of membrane proteins and their interactions with lipid membranes is of paramount importance since lipid-protein interactions can shape membrane protein conformations and ultimately define their functional states.In this Account, we report selected studies from our group integrating MAS and OS-ssNMR techniques to give a comprehensive view of the biological processes occurring at cellular membranes. We focus on the main experiments for both techniques, with an emphasis on new implementation to increase both sensitivity and spectral resolution. We also describe how the structural constraints derived from both isotropic and anisotropic NMR parameters are integrated into dynamic structural modeling using replica-averaged orientational-restrained molecular dynamics simulations (RAOR-MD). We showcase small membrane proteins that are involved in Ca2+ transport and regulate cardiac and skeletal muscle contractility: phospholamban (PLN, 6 kDa), sarcolipin (SLN, 4 kDa), and DWORF (4 kDa). We summarize our results for the structures of these polypeptides free and in complex with the sarcoplasmic reticulum (SR) Ca2+-ATPase (SERCA, 110 kDa). Additionally, we illustrate the progress toward the determination of the structural topology of a six transmembrane protein associated with succinate and acetate transport (SatP, hexamer 120 kDa). From these examples, the integrated MAS and OS-ssNMR approach, in combination with modern computational methods, emerges as a way to overcome the challenges posed by studying large membrane protein systems.
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25
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Barbot T, Beswick V, Montigny C, Quiniou É, Jamin N, Mouawad L. Deciphering the Mechanism of Inhibition of SERCA1a by Sarcolipin Using Molecular Simulations. Front Mol Biosci 2021; 7:606254. [PMID: 33614704 PMCID: PMC7890198 DOI: 10.3389/fmolb.2020.606254] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 11/06/2020] [Indexed: 12/02/2022] Open
Abstract
SERCA1a is an ATPase calcium pump that transports Ca2+ from the cytoplasm to the sarco/endoplasmic reticulum lumen. Sarcolipin (SLN), a transmembrane peptide, regulates the activity of SERCA1a by decreasing its Ca2+ transport rate, but its mechanism of action is still not well-understood. To decipher this mechanism, we have performed normal mode analysis in the all-atom model, with the SERCA1a-SLN complex, or the isolated SERCA1a, embedded in an explicit membrane. The comparison of the results allowed us to provide an explanation at the atomic level for the action of SLN that is in good agreement with experimental observations. In our analyses, the presence of SLN locally perturbs the TM6 transmembrane helix and as a consequence modifies the position of D800, one of the key metal-chelating residues. Additionally, it reduces the flexibility of the gating residues, V304, and E309 in TM4, at the entrance of the Ca2+ binding sites, which would decrease the affinity for Ca2+. Unexpectedly, SLN has also an effect on the ATP binding site more than 35 Å away, due to the straightening of TM5, a long helix considered as the spine of the protein. The straightening of TM5 modifies the structure of the P-N linker that sits above it, and which comprises the 351DKTG354 conserved motif, resulting in an increase of the distance between ATP and the phosphorylation site. As a consequence, the turn-over rate could be affected. All this gives SERCA1a the propensity to go toward a Ca2+ low-affinity E2-like state in the presence of SLN and toward a Ca2+ high-affinity E1-like state in the absence of SLN. In addition to a general mechanism of inhibition of SERCA1a regulatory peptides, this study also provides an insight into the conformational transition between the E2 and E1 states.
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Affiliation(s)
- Thomas Barbot
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Veronica Beswick
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France.,Physics Department, Evry-Val-d'Essonne University, Paris-Saclay University, Evry, France
| | - Cédric Montigny
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Éric Quiniou
- CNRS UMR9187 / INSERM U1196, Institut Curie, PSL Research University, Université Paris-Saclay, Orsay, France
| | - Nadège Jamin
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Liliane Mouawad
- CNRS UMR9187 / INSERM U1196, Institut Curie, PSL Research University, Université Paris-Saclay, Orsay, France
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26
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Csizmadia G, Erdős G, Tordai H, Padányi R, Tosatto S, Dosztányi Z, Hegedűs T. The MemMoRF database for recognizing disordered protein regions interacting with cellular membranes. Nucleic Acids Res 2021; 49:D355-D360. [PMID: 33119751 PMCID: PMC7778998 DOI: 10.1093/nar/gkaa954] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Revised: 09/25/2020] [Accepted: 10/28/2020] [Indexed: 12/19/2022] Open
Abstract
Protein and lipid membrane interactions play fundamental roles in a large number of cellular processes (e.g. signalling, vesicle trafficking, or viral invasion). A growing number of examples indicate that such interactions can also rely on intrinsically disordered protein regions (IDRs), which can form specific reversible interactions not only with proteins but also with lipids. We named IDRs involved in such membrane lipid-induced disorder-to-order transition as MemMoRFs, in an analogy to IDRs exhibiting disorder-to-order transition upon interaction with protein partners termed Molecular Recognition Features (MoRFs). Currently, both the experimental detection and computational characterization of MemMoRFs are challenging, and information about these regions are scattered in the literature. To facilitate the related investigations we generated a comprehensive database of experimentally validated MemMoRFs based on manual curation of literature and structural data. To characterize the dynamics of MemMoRFs, secondary structure propensity and flexibility calculated from nuclear magnetic resonance chemical shifts were incorporated into the database. These data were supplemented by inclusion of sentences from papers, functional data and disease-related information. The MemMoRF database can be accessed via a user-friendly interface at https://memmorf.hegelab.org, potentially providing a central resource for the characterization of disordered regions in transmembrane and membrane-associated proteins.
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Affiliation(s)
- Georgina Csizmadia
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest 1094, Hungary
| | - Gábor Erdős
- MTA-ELTE Lendület Bioinformatics Research Group, Department of Biochemistry, Eötvös Loránd University, Budapest 1117, Hungary
| | - Hedvig Tordai
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest 1094, Hungary
| | - Rita Padányi
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest 1094, Hungary
| | - Silvio Tosatto
- Department of Biomedical Sciences, University of Padua, Padua 35131, Italy
| | - Zsuzsanna Dosztányi
- MTA-ELTE Lendület Bioinformatics Research Group, Department of Biochemistry, Eötvös Loránd University, Budapest 1117, Hungary
| | - Tamás Hegedűs
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest 1094, Hungary
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27
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Montigny C, Huang DL, Beswick V, Barbot T, Jaxel C, le Maire M, Zheng JS, Jamin N. Sarcolipin alters SERCA1a interdomain communication by impairing binding of both calcium and ATP. Sci Rep 2021; 11:1641. [PMID: 33452371 PMCID: PMC7810697 DOI: 10.1038/s41598-021-81061-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 12/31/2020] [Indexed: 01/08/2023] Open
Abstract
Sarcolipin (SLN), a single-spanning membrane protein, is a regulator of the sarco-endoplasmic reticulum Ca2+-ATPase (SERCA1a). Chemically synthesized SLN, palmitoylated or not (pSLN or SLN), and recombinant wild-type rabbit SERCA1a expressed in S. cerevisiae design experimental conditions that provide a deeper understanding of the functional role of SLN on the regulation of SERCA1a. Our data show that chemically synthesized SLN interacts with recombinant SERCA1a, with calcium-deprived E2 state as well as with calcium-bound E1 state. This interaction hampers the binding of calcium in agreement with published data. Unexpectedly, SLN has also an allosteric effect on SERCA1a transport activity by impairing the binding of ATP. Our results reveal that SLN significantly slows down the E2 to Ca2.E1 transition of SERCA1a while it affects neither phosphorylation nor dephosphorylation. Comparison with chemically synthesized SLN deprived of acylation demonstrates that palmitoylation is not necessary for either inhibition or association with SERCA1a. However, it has a small but statistically significant effect on SERCA1a phosphorylation when various ratios of SLN-SERCA1a or pSLN-SERCA1a are tested.
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Affiliation(s)
- Cédric Montigny
- CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, 91198, Gif-sur-Yvette, France.
| | - Dong Liang Huang
- Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, 230027, China
| | - Veronica Beswick
- CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, 91198, Gif-sur-Yvette, France
- Department of Physics, Evry-Val-d'Essonne University, 91025, Evry, France
| | - Thomas Barbot
- CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, 91198, Gif-sur-Yvette, France
| | - Christine Jaxel
- CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, 91198, Gif-sur-Yvette, France
| | - Marc le Maire
- CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, 91198, Gif-sur-Yvette, France
| | - Ji-Shen Zheng
- Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, 230027, China.
| | - Nadège Jamin
- CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, 91198, Gif-sur-Yvette, France
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28
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Dyla M, Kjærgaard M, Poulsen H, Nissen P. Structure and Mechanism of P-Type ATPase Ion Pumps. Annu Rev Biochem 2020; 89:583-603. [PMID: 31874046 DOI: 10.1146/annurev-biochem-010611-112801] [Citation(s) in RCA: 95] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
P-type ATPases are found in all kingdoms of life and constitute a wide range of cation transporters, primarily for H+, Na+, K+, Ca2+, and transition metal ions such as Cu(I), Zn(II), and Cd(II). They have been studied through a wide range of techniques, and research has gained very significant insight on their transport mechanism and regulation. Here, we review the structure, function, and dynamics of P2-ATPases including Ca2+-ATPases and Na,K-ATPase. We highlight mechanisms of functional transitions that are associated with ion exchange on either side of the membrane and how the functional cycle is regulated by interaction partners, autoregulatory domains, and off-cycle states. Finally, we discuss future perspectives based on emerging techniques and insights.
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Affiliation(s)
- Mateusz Dyla
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark; .,Danish Research Institute of Translational Neuroscience (DANDRITE), Nordic European Molecular Biology Laboratory (EMBL) Partnership for Molecular Medicine, 8000 Aarhus, Denmark
| | - Magnus Kjærgaard
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark; .,Danish Research Institute of Translational Neuroscience (DANDRITE), Nordic European Molecular Biology Laboratory (EMBL) Partnership for Molecular Medicine, 8000 Aarhus, Denmark
| | - Hanne Poulsen
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark; .,Danish Research Institute of Translational Neuroscience (DANDRITE), Nordic European Molecular Biology Laboratory (EMBL) Partnership for Molecular Medicine, 8000 Aarhus, Denmark
| | - Poul Nissen
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark; .,Danish Research Institute of Translational Neuroscience (DANDRITE), Nordic European Molecular Biology Laboratory (EMBL) Partnership for Molecular Medicine, 8000 Aarhus, Denmark
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29
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Phospholamban and sarcolipin prevent thermal inactivation of sarco(endo)plasmic reticulum Ca2+-ATPases. Biochem J 2020; 477:4281-4294. [PMID: 33111944 DOI: 10.1042/bcj20200346] [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: 04/27/2020] [Revised: 10/15/2020] [Accepted: 10/28/2020] [Indexed: 12/31/2022]
Abstract
Na+-K+-ATPase from mice lacking the γ subunit exhibits decreased thermal stability. Phospholamban (PLN) and sarcolipin (SLN) are small homologous proteins that regulate sarco(endo)plasmic reticulum Ca2+-ATPases (SERCAs) with properties similar to the γ subunit, through physical interactions with SERCAs. Here, we tested the hypothesis that PLN and SLN may protect against thermal inactivation of SERCAs. HEK-293 cells were co-transfected with different combinations of cDNAs encoding SERCA2a, PLN, a PLN mutant (N34A) that cannot bind to SERCA2a, and SLN. One-half of the cells were heat stressed at 40°C for 1 h (HS), and one-half were maintained at 37°C (CTL) before harvesting the cells and isolating microsomes. Compared with CTL, maximal SERCA activity was reduced by 25-35% following HS in cells that expressed either SERCA2a alone or SERCA2a and mutant PLN (N34A) whereas no change in maximal SERCA2a activity was observed in cells that co-expressed SERCA2a and either PLN or SLN following HS. Increases in SERCA2a carbonyl group content and nitrotyrosine levels that were detected following HS in cells that expressed SERCA2a alone were prevented in cells co-expressing SERCA2a with PLN or SLN, whereas co-expression of SERCA2a with mutant PLN (N34A) only prevented carbonyl group formation. In other experiments using knock-out mice, we found that thermal inactivation of SERCA was increased in cardiac left ventricle samples from Pln-null mice and in diaphragm samples from Sln-null mice, compared with WT littermates. Our results show that both PLN and SLN form a protective interaction with SERCA pumps during HS, preventing nitrosylation and oxidation of SERCA and thus preserving its maximal activity.
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30
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Raguimova ON, Aguayo-Ortiz R, Robia SL, Espinoza-Fonseca LM. Dynamics-Driven Allostery Underlies Ca 2+-Mediated Release of SERCA Inhibition by Phospholamban. Biophys J 2020; 119:1917-1926. [PMID: 33069270 PMCID: PMC7677127 DOI: 10.1016/j.bpj.2020.09.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 09/17/2020] [Accepted: 09/18/2020] [Indexed: 12/20/2022] Open
Abstract
Sarcoplasmic reticulum (SR) Ca2+-ATPase (SERCA) and phospholamban (PLB) are essential for intracellular Ca2+ transport in myocytes. Ca2+-dependent activation of SERCA-PLB provides a control function that regulates cytosolic and SR Ca2+ levels. Although experimental and computational studies alone have led to a greater insight into SERCA-PLB regulation, the structural mechanisms for Ca2+ binding reversing inhibition of the complex remain poorly understood. Therefore, we have performed atomistic simulations totaling 32.7 μs and cell-based intramolecular fluorescence resonance energy transfer (FRET) experiments to determine structural changes of PLB-bound SERCA in response to binding of a single Ca2+ ion. Complementary MD simulations and FRET experiments showed that open-to-closed transitions in the structure of the headpiece underlie PLB inhibition of SERCA, and binding of a single Ca2+ ion is sufficient to shift the protein population toward a structurally closed structure of the complex. Closure is accompanied by functional interactions between the N-domain β5-β6 loop and the A-domain and the displacement of the catalytic phosphorylation domain toward a competent structure. We propose that reversal of SERCA-PLB inhibition is achieved by stringing together its controlling modules (A-domain and loop Nβ5-β6) with catalytic elements (P-domain) to regulate function during intracellular Ca2+ signaling. We conclude that binding of a single Ca2+ is a critical mediator of allosteric signaling that dictates structural changes and motions that relieve SERCA inhibition by PLB. Understanding allosteric regulation is of paramount importance to guide therapeutic modulation of SERCA and other evolutionarily related ion-motive ATPases.
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Affiliation(s)
- Olga N Raguimova
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, Illinois
| | - Rodrigo Aguayo-Ortiz
- Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan
| | - Seth L Robia
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, Illinois
| | - L Michel Espinoza-Fonseca
- Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan.
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31
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Aguayo-Ortiz R, Espinoza-Fonseca LM. Atomistic Structure and Dynamics of the Ca 2+-ATPase Bound to Phosphorylated Phospholamban. Int J Mol Sci 2020; 21:ijms21197261. [PMID: 33019581 PMCID: PMC7583845 DOI: 10.3390/ijms21197261] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 09/29/2020] [Accepted: 09/29/2020] [Indexed: 01/22/2023] Open
Abstract
Sarcoplasmic reticulum Ca2+-ATPase (SERCA) and phospholamban (PLB) are essential components of the cardiac Ca2+ transport machinery. PLB phosphorylation at residue Ser16 (pSer16) enhances SERCA activity in the heart via an unknown structural mechanism. Here, we report a fully atomistic model of SERCA bound to phosphorylated PLB and study its structural dynamics on the microsecond time scale using all-atom molecular dynamics simulations in an explicit lipid bilayer and water environment. The unstructured N-terminal phosphorylation domain of PLB samples different orientations and covers a broad area of the cytosolic domain of SERCA but forms a stable complex mediated by pSer16 interactions with a binding site formed by SERCA residues Arg324/Lys328. PLB phosphorylation does not affect the interaction between the transmembrane regions of the two proteins; however, pSer16 stabilizes a disordered structure of the N-terminal phosphorylation domain that releases key inhibitory contacts between SERCA and PLB. We found that PLB phosphorylation is sufficient to guide the structural transitions of the cytosolic headpiece that are required to produce a competent structure of SERCA. We conclude that PLB phosphorylation serves as an allosteric molecular switch that releases inhibitory contacts and strings together the catalytic elements required for SERCA activation. This atomistic model represents a vivid atomic-resolution visualization of SERCA bound to phosphorylated PLB and provides previously inaccessible insights into the structural mechanism by which PLB phosphorylation releases SERCA inhibition in the heart.
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Affiliation(s)
- Rodrigo Aguayo-Ortiz
- Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, MI 48109, USA;
- Departamento de Fisicoquímica, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
| | - L. Michel Espinoza-Fonseca
- Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, MI 48109, USA;
- Correspondence: ; Tel.: +1-734-998-7500
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32
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Sarcoplasmic reticulum calcium mishandling: central tenet in heart failure? Biophys Rev 2020; 12:865-878. [PMID: 32696300 DOI: 10.1007/s12551-020-00736-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 07/08/2020] [Indexed: 12/17/2022] Open
Abstract
Excitation-contraction coupling links excitation of the sarcolemmal surface membrane to mechanical contraction. In the heart this link is established via a Ca2+-induced Ca2+ release process, which, following sarcolemmal depolarisation, prompts Ca2+ release from the sarcoplasmic reticulum (SR) though the ryanodine receptor (RyR2). This substantially raises the cytoplasmic Ca2+ concentration to trigger systole. In diastole, Ca2+ is removed from the cytoplasm, primarily via the sarcoplasmic-endoplasmic reticulum Ca2+-dependent ATPase (SERCA) pump on the SR membrane, returning Ca2+ to the SR store. Ca2+ movement across the SR is thus fundamental to the systole/diastole cycle and plays an essential role in maintaining cardiac contractile function. Altered SR Ca2+ homeostasis (due to disrupted Ca2+ release, storage, and reuptake pathways) is a central tenet of heart failure and contributes to depressed contractility, impaired relaxation, and propensity to arrhythmia. This review will focus on the molecular mechanisms that underlie asynchronous Ca2+ cycling around the SR in the failing heart. Further, this review will illustrate that the combined effects of expression changes and disruptions to RyR2 and SERCA2a regulatory pathways are critical to the pathogenesis of heart failure.
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Alford RF, Smolin N, Young HS, Gray JJ, Robia SL. Protein docking and steered molecular dynamics suggest alternative phospholamban-binding sites on the SERCA calcium transporter. J Biol Chem 2020; 295:11262-11274. [PMID: 32554805 DOI: 10.1074/jbc.ra120.012948] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 06/16/2020] [Indexed: 01/27/2023] Open
Abstract
The transport activity of the sarco(endo)plasmic reticulum calcium ATPase (SERCA) in cardiac myocytes is modulated by an inhibitory interaction with a transmembrane peptide, phospholamban (PLB). Previous biochemical studies have revealed that PLB interacts with a specific inhibitory site on SERCA, and low-resolution structural evidence suggests that PLB interacts with distinct alternative sites on SERCA. High-resolution details of the structural determinants of SERCA regulation have been elusive because of the dynamic nature of the regulatory complex. In this study, we used computational approaches to develop a structural model of SERCA-PLB interactions to gain a mechanistic understanding of PLB-mediated SERCA transport regulation. We combined steered molecular dynamics and membrane protein-protein docking experiments to achieve both a global search and all-atom force calculations to determine the relative affinities of PLB for candidate sites on SERCA. We modeled the binding of PLB to several SERCA conformations, representing different enzymatic states sampled during the calcium transport catalytic cycle. The results of the steered molecular dynamics and docking experiments indicated that the canonical PLB-binding site (comprising transmembrane helices M2, M4, and M9) is the preferred site. This preference was even more stringent for a superinhibitory PLB variant. Interestingly, PLB-binding specificity became more ambivalent for other SERCA conformers. These results provide evidence for polymorphic PLB interactions with novel sites on M3 and with the outside of the SERCA helix M9. Our findings are compatible with previous physical measurements that suggest that PLB interacts with multiple binding sites, conferring dynamic responsiveness to changing physiological conditions.
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Affiliation(s)
- Rebecca F Alford
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland, USA
| | - Nikolai Smolin
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Cardiovascular Research Institute, Loyola University Chicago, Maywood, Illinois, USA
| | - Howard S Young
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Jeffrey J Gray
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland, USA
| | - Seth L Robia
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Cardiovascular Research Institute, Loyola University Chicago, Maywood, Illinois, USA
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Aguayo-Ortiz R, Espinoza-Fonseca LM. Linking Biochemical and Structural States of SERCA: Achievements, Challenges, and New Opportunities. Int J Mol Sci 2020; 21:ijms21114146. [PMID: 32532023 PMCID: PMC7313052 DOI: 10.3390/ijms21114146] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 06/05/2020] [Accepted: 06/08/2020] [Indexed: 02/07/2023] Open
Abstract
Sarcoendoplasmic reticulum calcium ATPase (SERCA), a member of the P-type ATPase family of ion and lipid pumps, is responsible for the active transport of Ca2+ from the cytoplasm into the sarcoplasmic reticulum lumen of muscle cells, into the endoplasmic reticulum (ER) of non-muscle cells. X-ray crystallography has proven to be an invaluable tool in understanding the structural changes of SERCA, and more than 70 SERCA crystal structures representing major biochemical states (defined by bound ligand) have been deposited in the Protein Data Bank. Consequently, SERCA is one of the best characterized components of the calcium transport machinery in the cell. Emerging approaches in the field, including spectroscopy and molecular simulation, now help integrate and interpret this rich structural information to understand the conformational transitions of SERCA that occur during activation, inhibition, and regulation. In this review, we provide an overview of the crystal structures of SERCA, focusing on identifying metrics that facilitate structure-based categorization of major steps along the catalytic cycle. We examine the integration of crystallographic data with different biophysical approaches and computational methods to link biochemical and structural states of SERCA that are populated in the cell. Finally, we discuss the challenges and new opportunities in the field, including structural elucidation of functionally important and novel regulatory complexes of SERCA, understanding the structural basis of functional divergence among homologous SERCA regulators, and bridging the gap between basic and translational research directed toward therapeutic modulation of SERCA.
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35
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Live-Cell Cardiac-Specific High-Throughput Screening Platform for Drug-Like Molecules that Enhance Ca 2+ Transport. Cells 2020; 9:cells9051170. [PMID: 32397211 PMCID: PMC7291019 DOI: 10.3390/cells9051170] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 05/05/2020] [Accepted: 05/06/2020] [Indexed: 12/25/2022] Open
Abstract
We engineered a concatenated fluorescent biosensor and dual-wavelength fluorescence lifetime (FLT) detection, to perform high-throughput screening (HTS) in living cells for discovery of potential heart-failure drugs. Heart failure is correlated with insufficient activity of the sarcoplasmic reticulum Ca-pump (SERCA2a), often due to excessive inhibition by phospholamban (PLB), a small transmembrane protein. We sought to discover small molecules that restore SERCA2a activity by disrupting this inhibitory interaction between PLB and SERCA2a. Our approach was to fluorescently tag the two proteins and measure fluorescence resonance energy transfer (FRET) to detect changes in binding or structure of the complex. To optimize sensitivity to these changes, we engineered a biosensor that concatenates the two fluorescently labeled proteins on a single polypeptide chain. This SERCA2a-PLB FRET biosensor construct is functionally active and effective for HTS. By implementing 2-wavelength FLT detection at extremely high speed during primary HTS, we culled fluorescent compounds as false-positive Hits. In pilot screens, we identified Hits that alter the SERCA2a-PLB interaction, and a newly developed secondary calcium uptake assay revealed both activators and inhibitors of Ca-transport. We are implementing this approach for large-scale screens to discover new drug-like modulators of SERCA2a-PLB interactions for heart failure therapeutic development.
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36
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Fernández-de Gortari E, Aguayo-Ortiz R, Autry JM, Michel Espinoza-Fonseca L. A hallmark of phospholamban functional divergence is located in the N-terminal phosphorylation domain. Comput Struct Biotechnol J 2020; 18:705-713. [PMID: 32257054 PMCID: PMC7114604 DOI: 10.1016/j.csbj.2020.02.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 02/23/2020] [Accepted: 02/23/2020] [Indexed: 01/12/2023] Open
Abstract
Sarcoplasmic reticulum Ca2+ pump (SERCA) is a critical component of the Ca2+ transport machinery in myocytes. There is clear evidence for regulation of SERCA activity by PLB, whose activity is modulated by phosphorylation of its N-terminal domain (residues 1–25), but there is less clear evidence for the role of this domain in PLB’s functional divergence. It is widely accepted that only sarcolipin (SLN), a protein that shares substantial homology with PLB, uncouples SERCA Ca2+ transport from ATP hydrolysis by inducing a structural change of its energy-transduction domain; yet, experimental evidence shows that the transmembrane domain of PLB (residues 26–52, PLB26–52) partially uncouples SERCA in vitro. These apparently conflicting mechanisms suggest that PLB’s uncoupling activity is encoded in its transmembrane domain, and that it is controlled by the N-terminal phosphorylation domain. To test this hypothesis, we performed molecular dynamics simulations (MDS) of the binary complex between PLB26–52 and SERCA. Comparison between PLB26–52 and wild-type PLB (PLBWT) showed no significant changes in the stability and orientation of the transmembrane helix, indicating that PLB26–52 forms a native-like complex with SERCA. MDS showed that PLB26–52 produces key intermolecular contacts and structural changes required for inhibition, in agreement with studies showing that PLB26–52 inhibits SERCA. However, deletion of the N-terminal phosphorylation domain facilitates an order-to-disorder shift in the energy-transduction domain associated with uncoupling of SERCA, albeit weaker than that induced by SLN. This mechanistic evidence reveals that the N-terminal phosphorylation domain of PLB is a primary contributor to the functional divergence among homologous SERCA regulators.
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Affiliation(s)
- Eli Fernández-de Gortari
- Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Rodrigo Aguayo-Ortiz
- Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Joseph M Autry
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.,Biophysical Technology Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - L Michel Espinoza-Fonseca
- Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, MI 48109, USA
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37
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Structural dynamics of P-type ATPase ion pumps. Biochem Soc Trans 2020; 47:1247-1257. [PMID: 31671180 DOI: 10.1042/bst20190124] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 09/06/2019] [Accepted: 09/16/2019] [Indexed: 02/04/2023]
Abstract
P-type ATPases transport ions across biological membranes against concentration gradients and are essential for all cells. They use the energy from ATP hydrolysis to propel large intramolecular movements, which drive vectorial transport of ions. Tight coordination of the motions of the pump is required to couple the two spatially distant processes of ion binding and ATP hydrolysis. Here, we review our current understanding of the structural dynamics of P-type ATPases, focusing primarily on Ca2+ pumps. We integrate different types of information that report on structural dynamics, primarily time-resolved fluorescence experiments including single-molecule Förster resonance energy transfer and molecular dynamics simulations, and interpret them in the framework provided by the numerous crystal structures of sarco/endoplasmic reticulum Ca2+-ATPase. We discuss the challenges in characterizing the dynamics of membrane pumps, and the likely impact of new technologies on the field.
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38
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Peterková L, Kmoníčková E, Ruml T, Rimpelová S. Sarco/Endoplasmic Reticulum Calcium ATPase Inhibitors: Beyond Anticancer Perspective. J Med Chem 2020; 63:1937-1963. [PMID: 32030976 DOI: 10.1021/acs.jmedchem.9b01509] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The sarco/endoplasmic reticulum calcium ATPase (SERCA), which plays a key role in the maintenance of Ca2+ ion homeostasis, is an extensively studied enzyme, the inhibition of which has a considerable impact on cell life and death decision. To date, several SERCA inhibitors have been thoroughly studied and the most notable one, a derivative of the sesquiterpene lactone thapsigargin, is gradually approaching a clinical application. Meanwhile, new compounds with SERCA-inhibiting properties of natural, synthetic, or semisynthetic origin are being discovered and/or developed; some of these might also be suitable for the development of new drugs with improved performance. This review brings an up-to-date comprehensive overview of recently discovered compounds with the potential of SERCA inhibition, discusses their mechanism of action, and highlights their potential clinical applications, such as cancer treatment.
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Affiliation(s)
- Lucie Peterková
- Department of Biochemistry and Microbiology, University of Chemistry and Technology Prague, Technická 5, 166 28, Prague 6, Czech Republic
| | - Eva Kmoníčková
- Faculty of Medicine in Pilsen, Charles University, Alej Svobody 76, 323 00 Pilsen, Czech Republic
| | - Tomáš Ruml
- Department of Biochemistry and Microbiology, University of Chemistry and Technology Prague, Technická 5, 166 28, Prague 6, Czech Republic
| | - Silvie Rimpelová
- Department of Biochemistry and Microbiology, University of Chemistry and Technology Prague, Technická 5, 166 28, Prague 6, Czech Republic.,Faculty of Medicine in Pilsen, Charles University, Alej Svobody 76, 323 00 Pilsen, Czech Republic
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39
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Chen J, Sitsel A, Benoy V, Sepúlveda MR, Vangheluwe P. Primary Active Ca 2+ Transport Systems in Health and Disease. Cold Spring Harb Perspect Biol 2020; 12:cshperspect.a035113. [PMID: 31501194 DOI: 10.1101/cshperspect.a035113] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Calcium ions (Ca2+) are prominent cell signaling effectors that regulate a wide variety of cellular processes. Among the different players in Ca2+ homeostasis, primary active Ca2+ transporters are responsible for keeping low basal Ca2+ levels in the cytosol while establishing steep Ca2+ gradients across intracellular membranes or the plasma membrane. This review summarizes our current knowledge on the three types of primary active Ca2+-ATPases: the sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) pumps, the secretory pathway Ca2+- ATPase (SPCA) isoforms, and the plasma membrane Ca2+-ATPase (PMCA) Ca2+-transporters. We first discuss the Ca2+ transport mechanism of SERCA1a, which serves as a reference to describe the Ca2+ transport of other Ca2+ pumps. We further highlight the common and unique features of each isoform and review their structure-function relationship, expression pattern, regulatory mechanisms, and specific physiological roles. Finally, we discuss the increasing genetic and in vivo evidence that links the dysfunction of specific Ca2+-ATPase isoforms to a broad range of human pathologies, and highlight emerging therapeutic strategies that target Ca2+ pumps.
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Affiliation(s)
- Jialin Chen
- Laboratory of Cellular Transport Systems, Department of Cellular and Molecular Medicine, KU Leuven, 3000 Leuven, Belgium
| | - Aljona Sitsel
- Laboratory of Cellular Transport Systems, Department of Cellular and Molecular Medicine, KU Leuven, 3000 Leuven, Belgium
| | - Veronick Benoy
- Laboratory of Cellular Transport Systems, Department of Cellular and Molecular Medicine, KU Leuven, 3000 Leuven, Belgium
| | - M Rosario Sepúlveda
- Department of Cell Biology, Faculty of Sciences, University of Granada, 18071 Granada, Spain
| | - Peter Vangheluwe
- Laboratory of Cellular Transport Systems, Department of Cellular and Molecular Medicine, KU Leuven, 3000 Leuven, Belgium
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40
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Makarewich CA. The hidden world of membrane microproteins. Exp Cell Res 2020; 388:111853. [PMID: 31978386 DOI: 10.1016/j.yexcr.2020.111853] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 01/03/2020] [Accepted: 01/14/2020] [Indexed: 12/26/2022]
Abstract
Proteins are critical components of biological membranes and play key roles in many essential cellular processes. Membrane proteins are a structurally and functionally diverse family of proteins that have recently expanded to include a number of newly discovered tiny proteins called microproteins, or micropeptides. These microproteins are generated from small open reading frames, which produce protein products that are less than 100 amino acids in length. While not all microproteins are membrane proteins, this review will focus specifically on this subclass to highlight some of the important biological activities that have been ascribed to these molecules and to emphasize their promise as exciting new players in membrane biology.
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Affiliation(s)
- Catherine A Makarewich
- The Heart Institute and Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States.
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41
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Glaves JP, Primeau JO, Gorski PA, Espinoza-Fonseca LM, Lemieux MJ, Young HS. Interaction of a Sarcolipin Pentamer and Monomer with the Sarcoplasmic Reticulum Calcium Pump, SERCA. Biophys J 2019; 118:518-531. [PMID: 31858977 DOI: 10.1016/j.bpj.2019.11.3385] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 10/30/2019] [Accepted: 11/18/2019] [Indexed: 11/27/2022] Open
Abstract
The sequential rise and fall of cytosolic calcium underlies the contraction-relaxation cycle of muscle cells. Whereas contraction is initiated by the release of calcium from the sarcoplasmic reticulum, muscle relaxation involves the active transport of calcium back into the sarcoplasmic reticulum. This reuptake of calcium is catalyzed by the sarcoendoplasmic reticulum Ca2+-ATPase (SERCA), which plays a lead role in muscle contractility. The activity of SERCA is regulated by small membrane protein subunits, the most well-known being phospholamban (PLN) and sarcolipin (SLN). SLN physically interacts with SERCA and differentially regulates contractility in skeletal and atrial muscle. SLN has also been implicated in skeletal muscle thermogenesis. Despite these important roles, the structural mechanisms by which SLN modulates SERCA-dependent contractility and thermogenesis remain unclear. Here, we functionally characterized wild-type SLN and a pair of mutants, Asn4-Ala and Thr5-Ala, which yielded gain-of-function behavior comparable to what has been found for PLN. Next, we analyzed two-dimensional crystals of SERCA in the presence of wild-type SLN by electron cryomicroscopy. The fundamental units of the crystals are antiparallel dimer ribbons of SERCA, known for decades as an assembly of calcium-free SERCA molecules induced by the addition of decavanadate. A projection map of the SERCA-SLN complex was determined to a resolution of 8.5 Å, which allowed the direct visualization of an SLN pentamer. The SLN pentamer was found to interact with transmembrane segment M3 of SERCA, although the interaction appeared to be indirect and mediated by an additional density consistent with an SLN monomer. This SERCA-SLN complex correlated with the ability of SLN to decrease the maximal activity of SERCA, which is distinct from the ability of PLN to increase the maximal activity of SLN. Protein-protein docking and molecular dynamics simulations provided models for the SLN pentamer and the novel interaction between SERCA and an SLN monomer.
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Affiliation(s)
- John Paul Glaves
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Joseph O Primeau
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Przemek A Gorski
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
| | - L Michel Espinoza-Fonseca
- Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan
| | - M Joanne Lemieux
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Howard S Young
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada.
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42
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Newly Discovered Micropeptide Regulators of SERCA Form Oligomers but Bind to the Pump as Monomers. J Mol Biol 2019; 431:4429-4443. [PMID: 31449798 DOI: 10.1016/j.jmb.2019.07.037] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 07/26/2019] [Accepted: 07/31/2019] [Indexed: 12/22/2022]
Abstract
The recently-discovered single-span transmembrane proteins endoregulin (ELN), dwarf open reading frame (DWORF), myoregulin (MLN), and another-regulin (ALN) are reported to bind to the SERCA calcium pump in a manner similar to that of known regulators of SERCA activity, phospholamban (PLB) and sarcolipin (SLN). To determine how micropeptide assembly into oligomers affects the availability of the micropeptide to bind to SERCA in a regulatory complex, we used co-immunoprecipitation and fluorescence resonance energy transfer (FRET) to quantify micropeptide oligomerization and SERCA-binding. Micropeptides formed avid homo-oligomers with high-order stoichiometry (n > 2 protomers per homo-oligomer), but it was the monomeric form of all micropeptides that interacted with SERCA. In view of these two alternative binding interactions, we evaluated the possibility that oligomerization occurs at the expense of SERCA-binding. However, even the most avidly oligomeric micropeptide species still showed robust FRET with SERCA, and there was a surprising positive correlation between oligomerization affinity and SERCA-binding. This comparison of micropeptide family members suggests that the same structural determinants that support oligomerization are also important for binding to SERCA. Moreover, the unique oligomerization/SERCA-binding profile of DWORF is in harmony with its distinct role as a PLB-competing SERCA activator, in contrast to the inhibitory function of the other SERCA-binding micropeptides.
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43
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Martin PD, James ZM, Thomas DD. Effect of Phosphorylation on Interactions between Transmembrane Domains of SERCA and Phospholamban. Biophys J 2019; 114:2573-2583. [PMID: 29874608 DOI: 10.1016/j.bpj.2018.04.035] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 03/29/2018] [Accepted: 04/18/2018] [Indexed: 01/27/2023] Open
Abstract
We have used site-directed spin labeling and electron paramagnetic resonance (EPR) to map interactions between the transmembrane (TM) domains of the sarcoplasmic reticulum Ca2+-ATPase (SERCA) and phospholamban (PLB) as affected by PLB phosphorylation. In the cardiac sarcoplasmic reticulum, PLB binding to SERCA results in Ca-dependent enzyme inhibition, which is reversed by PLB phosphorylation at Ser16. Previous spectroscopic studies on SERCA-PLB have largely focused on the cytoplasmic domain of PLB, showing that phosphorylation induces a structural shift in this domain relative to SERCA. However, SERCA inhibition is due entirely to TM domain interactions. Therefore, we focus here on PLB's TM domain, attaching Cys-reactive spin labels at five different positions. In each case, continuous-wave EPR indicated moderate spin-label mobility, with the addition of SERCA revealing two populations, one indistinguishable from PLB alone and another with more restricted rotational mobility, presumably due to SERCA-binding. Phosphorylation had no effect on the rotational mobility of either component but significantly decreased the mole fraction of the restricted component. Solvent-accessibility experiments using power-saturation EPR and saturation-recovery EPR confirmed that these two spectral components were SERCA-bound and unbound PLB and showed that phosphorylation increased the overall lipid accessibility of the TM domain by increasing the fraction of unbound PLB. However-based on these results-at physiological levels of SERCA and PLB, most SERCA would have bound PLB even after phosphorylation. Additionally, no structural shift in the TM domain of SERCA-bound PLB was detected, as there were no significant changes in membrane insertion depth or its accessibility. Therefore, we conclude that under physiological conditions, the phosphorylation of PLB induces little or no change in the interaction of the TM domain with SERCA, so relief of inhibition is predominantly due to the previously observed structural shift in the cytoplasmic domain.
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Affiliation(s)
- Peter D Martin
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota; School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota
| | - Zachary M James
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington
| | - David D Thomas
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota; School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota.
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44
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Espinoza-Fonseca LM. Probing the effects of nonannular lipid binding on the stability of the calcium pump SERCA. Sci Rep 2019; 9:3349. [PMID: 30833659 PMCID: PMC6399444 DOI: 10.1038/s41598-019-40004-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 02/07/2019] [Indexed: 01/14/2023] Open
Abstract
The calcium pump SERCA is a transmembrane protein that is critical for calcium transport in cells. SERCA resides in an environment made up largely by the lipid bilayer, so lipids play a central role on its stability and function. Studies have provided insights into the effects of annular and bulk lipids on SERCA activation, but the role of a nonannular lipid site in the E2 intermediate state remains elusive. Here, we have performed microsecond molecular dynamics simulations to probe the effects of nonannular lipid binding on the stability and structural dynamics of the E2 state of SERCA. We found that the structural integrity and stability of the E2 state is independent of nonannular lipid binding, and that occupancy of a lipid molecule at this site does not modulate destabilization of the E2 state, a step required to initiate the transition toward the competent E1 state. We also found that binding of the nonannular lipid does not induce direct allosteric control of the intrinsic functional dynamics the E2 state. We conclude that nonannular lipid binding is not necessary for the stability of the E2 state, but we speculate that it becomes functionally significant during the E2-to-E1 transition of the pump.
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Affiliation(s)
- L Michel Espinoza-Fonseca
- Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, MI, 48109, USA.
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45
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Affiliation(s)
- Evangelia G Kranias
- From the Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, OH (E.G.K.); and Cardiovascular Research Center, Department of Cardiology, Icahn School of Medicine at Mount Sinai, New York, NY (R.J.H.).
| | - Roger J Hajjar
- From the Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, OH (E.G.K.); and Cardiovascular Research Center, Department of Cardiology, Icahn School of Medicine at Mount Sinai, New York, NY (R.J.H.)
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46
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Sitsel A, De Raeymaecker J, Drachmann ND, Derua R, Smaardijk S, Andersen JL, Vandecaetsbeek I, Chen J, De Maeyer M, Waelkens E, Olesen C, Vangheluwe P, Nissen P. Structures of the heart specific SERCA2a Ca 2+-ATPase. EMBO J 2019; 38:embj.2018100020. [PMID: 30777856 DOI: 10.15252/embj.2018100020] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2018] [Revised: 12/29/2018] [Accepted: 01/10/2019] [Indexed: 12/11/2022] Open
Abstract
The sarcoplasmic/endoplasmic reticulum Ca2+-ATPase 2a (SERCA2a) performs active reuptake of cytoplasmic Ca2+ and is a major regulator of cardiac muscle contractility. Dysfunction or dysregulation of SERCA2a is associated with heart failure, while restoring its function is considered as a therapeutic strategy to restore cardiac performance. However, its structure has not yet been determined. Based on native, active protein purified from pig ventricular muscle, we present the first crystal structures of SERCA2a, determined in the CPA-stabilized E2-AlF4- form (3.3 Å) and the Ca2+-occluded [Ca2]E1-AMPPCP form (4.0 Å). The structures are similar to the skeletal muscle isoform SERCA1a pointing to a conserved mechanism. We seek to explain the kinetic differences between SERCA1a and SERCA2a. We find that several isoform-specific residues are acceptor sites for post-translational modifications. In addition, molecular dynamics simulations predict that isoform-specific residues support distinct intramolecular interactions in SERCA2a and SERCA1a. Our experimental observations further indicate that isoform-specific intramolecular interactions are functionally relevant, and may explain the kinetic differences between SERCA2a and SERCA1a.
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Affiliation(s)
- Aljona Sitsel
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.,Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium.,Center for Membrane Proteins in Cells and Disease - PUMPkin, Danish National Research Foundation, Aarhus C, Denmark.,Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Aarhus C, Denmark
| | | | - Nikolaj Düring Drachmann
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.,Center for Membrane Proteins in Cells and Disease - PUMPkin, Danish National Research Foundation, Aarhus C, Denmark
| | - Rita Derua
- Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium.,SyBioMa, KU Leuven, Leuven, Belgium
| | - Susanne Smaardijk
- Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Jacob Lauwring Andersen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.,Center for Membrane Proteins in Cells and Disease - PUMPkin, Danish National Research Foundation, Aarhus C, Denmark.,Department of Biomedicine, Aarhus University, Aarhus C, Denmark
| | | | - Jialin Chen
- Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | | | - Etienne Waelkens
- Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium.,SyBioMa, KU Leuven, Leuven, Belgium
| | - Claus Olesen
- Center for Membrane Proteins in Cells and Disease - PUMPkin, Danish National Research Foundation, Aarhus C, Denmark .,Department of Biomedicine, Aarhus University, Aarhus C, Denmark
| | - Peter Vangheluwe
- Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Poul Nissen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark .,Center for Membrane Proteins in Cells and Disease - PUMPkin, Danish National Research Foundation, Aarhus C, Denmark.,Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Aarhus C, Denmark
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Glaves JP, Primeau JO, Espinoza-Fonseca LM, Lemieux MJ, Young HS. The Phospholamban Pentamer Alters Function of the Sarcoplasmic Reticulum Calcium Pump SERCA. Biophys J 2019; 116:633-647. [PMID: 30712785 DOI: 10.1016/j.bpj.2019.01.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 11/30/2018] [Accepted: 01/11/2019] [Indexed: 11/17/2022] Open
Abstract
The interaction of phospholamban (PLN) with the sarco-endoplasmic reticulum Ca2+-ATPase (SERCA) pump is a major regulatory axis in cardiac muscle contractility. The prevailing model involves reversible inhibition of SERCA by monomeric PLN and storage of PLN as an inactive pentamer. However, this paradigm has been challenged by studies demonstrating that PLN remains associated with SERCA and that the PLN pentamer is required for the regulation of cardiac contractility. We have previously used two-dimensional (2D) crystallization and electron microscopy to study the interaction between SERCA and PLN. To further understand this interaction, we compared small helical crystals and large 2D crystals of SERCA in the absence and presence of PLN. In both crystal forms, SERCA molecules are organized into identical antiparallel dimer ribbons. The dimer ribbons pack together with distinct crystal contacts in the helical versus large 2D crystals, which allow PLN differential access to potential sites of interaction with SERCA. Nonetheless, we show that a PLN oligomer interacts with SERCA in a similar manner in both crystal forms. In the 2D crystals, a PLN pentamer interacts with transmembrane segments M3 of SERCA and participates in a crystal contact that bridges neighboring SERCA dimer ribbons. In the helical crystals, an oligomeric form of PLN also interacts with M3 of SERCA, though the PLN oligomer straddles a SERCA-SERCA crystal contact. We conclude that the pentameric form of PLN interacts with M3 of SERCA and that it plays a distinct structural and functional role in SERCA regulation. The interaction of the pentamer places the cytoplasmic domains of PLN at the membrane surface proximal to the calcium entry funnel of SERCA. This interaction may cause localized perturbation of the membrane bilayer as a mechanism for increasing the turnover rate of SERCA.
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Affiliation(s)
- John Paul Glaves
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Joseph O Primeau
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
| | - L Michel Espinoza-Fonseca
- Center for Arrhythmia Research, Division of Cardiovascular Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - M Joanne Lemieux
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Howard S Young
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada.
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Mechanism of the E2 to E1 transition in Ca 2+ pump revealed by crystal structures of gating residue mutants. Proc Natl Acad Sci U S A 2018; 115:12722-12727. [PMID: 30482857 DOI: 10.1073/pnas.1815472115] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Ca2+-ATPase of sarcoplasmic reticulum (SERCA1a) pumps two Ca2+ per ATP hydrolyzed from the cytoplasm and two or three protons in the opposite direction. In the E2 state, after transferring Ca2+ into the lumen of sarcoplasmic reticulum, all of the acidic residues that coordinate Ca2+ are thought to be protonated, including the gating residue Glu309. Therefore a Glu309Gln substitution is not expected to significantly perturb the structure. Here we report crystal structures of the Glu309Gln and Glu309Ala mutants of SERCA1a under E2 conditions. The Glu309Gln mutant exhibits, unexpectedly, large structural rearrangements in both the cytoplasmic and transmembrane domains, apparently uncoupling them. However, the structure definitely represents E2 and, together with the help of quantum chemical calculations, allows us to postulate a mechanism for the E2 → E1 transition triggered by deprotonation of Glu309.
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Chen M, Xu D, Wu AZ, Kranias E, Lin SF, Chen PS, Chen Z. Phospholamban regulates nuclear Ca 2+ stores and inositol 1,4,5-trisphosphate mediated nuclear Ca 2+ cycling in cardiomyocytes. J Mol Cell Cardiol 2018; 123:185-197. [PMID: 30261161 DOI: 10.1016/j.yjmcc.2018.09.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 09/04/2018] [Accepted: 09/21/2018] [Indexed: 01/15/2023]
Abstract
AIMS Phospholamban (PLB) is the key regulator of the cardiac Ca2+ pump (SERCA2a)-mediated sarcoplasmic reticulum Ca2+ stores. We recently reported that PLB is highly concentrated in the nuclear envelope (NE) from where it can modulate perinuclear Ca2+ handling of the cardiomyocytes (CMs). Since inositol 1,4,5-trisphosphate (IP3) receptor (IP3R) mediates nuclear Ca2+ release, we examined whether the nuclear pool of PLB regulates IP3-induced nuclear Ca2+ handling. METHODS AND RESULTS Fluo-4 based confocal Ca2+ imaging was performed to measure Ca2+ dynamics across both nucleus and cytosol in saponin-permeabilized CMs isolated from wild-type (WT) or PLB-knockout (PLB-KO) mice. At diastolic intracellular Ca2+ ([Ca2+]i = 100 nM), the Fab fragment of the monoclonal PLB antibody (anti-PLB Fab) facilitated the formation and increased the length of spontaneous Ca2+ waves (SCWs) originating from the nuclear region in CMs from WT but not from PLB-KO mice. We next examined nuclear Ca2+ activities at basal condition and after sequential addition of IP3, anti-PLB Fab, and the IP3R inhibitor 2-aminoethoxydiphenyl borate (2-APB) at a series of [Ca2+]i. In WT mice, at 10 nM [Ca2+]i where ryanodine receptor (RyR2) based spontaneous Ca2+ sparks rarely occurred, IP3 increased fluorescence amplitude (F/F0) of overall nuclear region to 1.19 ± 0.02. Subsequent addition of anti-PLB Fab significantly decreased F/F0 to 1.09 ± 0.02. At 50 nM [Ca2+]i, anti-PLB Fab not only decreased the overall nuclear F/F0 previously elevated by IP3, but also increased the amplitude and duration of spark-like nuclear Ca2+ release events. These nuclear Ca2+ releases were blocked by 2-APB. At 100 nM [Ca2+]i, IP3 induced short SCWs originating from nucleus. Anti-PLB Fab transformed those short waves into long SCWs with propagation from the nucleus into the cytosol. In contrast, neither nuclear nor cytosolic Ca2+ dynamics was affected by anti-PLB Fab in CMs from PLB-KO mice in all these conditions. Furthermore, in WT CMs pretreated with RyR2 blocker tetracaine, IP3 and anti-PLB Fab still increased the magnitude of nuclear Ca2+ release but failed to regenerate SCWs. Finally, anti-PLB Fab increased low Ca2+ affinity mag-fluo 4 fluorescence intensity in the lumen of NE of nuclei isolated from WT but not in PLB-KO mice. CONCLUSION PLB regulates nuclear Ca2+ handling. By increasing Ca2+ uptake into lumen of the NE and perhaps other perinuclear membranes, the acute reversal of PLB inhibition decreases global Ca2+ concentration at rest in the nucleoplasm, and increases Ca2+ release into the nucleus, through mechanisms involving IP3R and RyR2 in the vicinity.
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Affiliation(s)
- Mu Chen
- Krannert Institute of Cardiology, Indiana University, Indianapolis, IN, USA; Department of Cardiology, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Dongzhu Xu
- Krannert Institute of Cardiology, Indiana University, Indianapolis, IN, USA; Cardiovascular Division, Institute of Clinical Medicine, Faculty of Medicine, University of Tsukuba, Japan
| | - Adonis Z Wu
- Krannert Institute of Cardiology, Indiana University, Indianapolis, IN, USA
| | - Evangelia Kranias
- Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Shien-Fong Lin
- Krannert Institute of Cardiology, Indiana University, Indianapolis, IN, USA; Institute of Biomedical Engineering, College of Electrical and Computer Engineering, National Chiao Tung University, Hsin-Chu, Taiwan
| | - Peng-Sheng Chen
- Krannert Institute of Cardiology, Indiana University, Indianapolis, IN, USA
| | - Zhenhui Chen
- Krannert Institute of Cardiology, Indiana University, Indianapolis, IN, USA.
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Glycophagy: An emerging target in pathology. Clin Chim Acta 2018; 484:298-303. [DOI: 10.1016/j.cca.2018.06.014] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 06/08/2018] [Accepted: 06/08/2018] [Indexed: 12/14/2022]
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