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Liggri PGV, Tsitsanou KE, Stamati ECV, Saitta F, Drakou CE, Leonidas DD, Fessas D, Zographos SE. The structure of AgamOBP5 in complex with the natural insect repellents Carvacrol and Thymol: Crystallographic, fluorescence and thermodynamic binding studies. Int J Biol Macromol 2023; 237:124009. [PMID: 36921814 DOI: 10.1016/j.ijbiomac.2023.124009] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 02/17/2023] [Accepted: 03/07/2023] [Indexed: 03/14/2023]
Abstract
Among several proteins participating in the olfactory perception process of insects, Odorant Binding Proteins (OBPs) are today considered valid targets for the discovery of compounds that interfere with their host-detection behavior. The 3D structures of Anopheles gambiae mosquito AgamOBP1 in complex with the known synthetic repellents DEET and Icaridin have provided valuable information on the structural characteristics that govern their selective binding. However, no structure of a plant-derived repellent bound to an OBP has been available until now. Herein, we present the novel three-dimensional crystal structures of AgamOBP5 in complex with two natural phenolic monoterpenoid repellents, Carvacrol and Thymol, and the MPD molecule. Structural analysis revealed that both monoterpenoids occupy a binding site (Site-1) by adopting two alternative conformations. An additional Carvacrol was also bound to a secondary site (Site-2) near the central cavity entrance. A protein-ligand hydrogen-bond network supplemented by van der Waals interactions spans the entire binding cavity, bridging α4, α6, and α3 helices and stabilizing the overall structure. Fluorescence competition and Differential Scanning Calorimetry experiments verified the presence of two binding sites and the stabilization effect on AgamOBP5. While Carvacrol and Thymol bind to Site-1 with equal affinity in the submicromolar range, they exhibit a significantly lower and distinct binding capacity for Site-2 with Kd's of ~7 μΜ and ~18 μΜ, respectively. Finally, a comparison of AgamOBP5 complexes with the AgamOBP4-Indole structure revealed that variations of ligand-interacting aminoacids such as A109T, I72M, A112L, and A105T cause two structurally similar and homologous proteins to display different binding specificities.
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Affiliation(s)
- Panagiota G V Liggri
- Institute of Chemical Biology, National Hellenic Research Foundation, 48 Vassileos Constantinou Avenue, 11635 Athens, Greece; Department of Biochemistry and Biotechnology, University of Thessaly, Biopolis, 41500 Larissa, Greece
| | - Katerina E Tsitsanou
- Institute of Chemical Biology, National Hellenic Research Foundation, 48 Vassileos Constantinou Avenue, 11635 Athens, Greece
| | - Evgenia C V Stamati
- Institute of Chemical Biology, National Hellenic Research Foundation, 48 Vassileos Constantinou Avenue, 11635 Athens, Greece; Department of Biochemistry and Biotechnology, University of Thessaly, Biopolis, 41500 Larissa, Greece
| | - Francesca Saitta
- Department of Food, Environmental and Nutritional Sciences, Università degli Studi di Milano, Via Celoria 2, 20133 Milano, Italy
| | - Christina E Drakou
- Institute of Chemical Biology, National Hellenic Research Foundation, 48 Vassileos Constantinou Avenue, 11635 Athens, Greece
| | - Demetres D Leonidas
- Department of Biochemistry and Biotechnology, University of Thessaly, Biopolis, 41500 Larissa, Greece
| | - Dimitrios Fessas
- Department of Food, Environmental and Nutritional Sciences, Università degli Studi di Milano, Via Celoria 2, 20133 Milano, Italy
| | - Spyros E Zographos
- Institute of Chemical Biology, National Hellenic Research Foundation, 48 Vassileos Constantinou Avenue, 11635 Athens, Greece.
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2
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Toke O. Structural and Dynamic Determinants of Molecular Recognition in Bile Acid-Binding Proteins. Int J Mol Sci 2022; 23:ijms23010505. [PMID: 35008930 PMCID: PMC8745080 DOI: 10.3390/ijms23010505] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 12/30/2021] [Accepted: 12/31/2021] [Indexed: 12/12/2022] Open
Abstract
Disorders in bile acid transport and metabolism have been related to a number of metabolic disease states, atherosclerosis, type-II diabetes, and cancer. Bile acid-binding proteins (BABPs), a subfamily of intracellular lipid-binding proteins (iLBPs), have a key role in the cellular trafficking and metabolic targeting of bile salts. Within the family of iLBPs, BABPs exhibit unique binding properties including positive binding cooperativity and site-selectivity, which in different tissues and organisms appears to be tailored to the local bile salt pool. Structural and biophysical studies of the past two decades have shed light on the mechanism of bile salt binding at the atomic level, providing us with a mechanistic picture of ligand entry and release, and the communication between the binding sites. In this review, we discuss the emerging view of bile salt recognition in intestinal- and liver-BABPs, with examples from both mammalian and non-mammalian species. The structural and dynamic determinants of the BABP-bile–salt interaction reviewed herein set the basis for the design and development of drug candidates targeting the transcellular traffic of bile salts in enterocytes and hepatocytes.
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Affiliation(s)
- Orsolya Toke
- Laboratory for NMR Spectroscopy, Structural Research Centre, Research Centre for Natural Sciences, 2 Magyar Tudósok Körútja, H-1117 Budapest, Hungary
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3
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Barbiroli A, Marengo M, Fessas D, Ragg E, Renzetti S, Bonomi F, Iametti S. Stabilization of beta-lactoglobulin by polyols and sugars against temperature-induced denaturation involves diverse and specific structural regions of the protein. Food Chem 2017; 234:155-162. [DOI: 10.1016/j.foodchem.2017.04.132] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 04/13/2017] [Accepted: 04/20/2017] [Indexed: 01/10/2023]
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4
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Horváth G, Biczók L, Majer Z, Kovács M, Micsonai A, Kardos J, Toke O. Structural insight into a partially unfolded state preceding aggregation in an intracellular lipid-binding protein. FEBS J 2017; 284:3637-3661. [DOI: 10.1111/febs.14264] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Revised: 08/15/2017] [Accepted: 09/05/2017] [Indexed: 12/15/2022]
Affiliation(s)
- Gergő Horváth
- Laboratory for NMR Spectroscopy; Research Centre for Natural Sciences; Hungarian Academy of Sciences; Budapest Hungary
| | - László Biczók
- Institute of Materials and Environmental Chemistry; Research Centre for Natural Sciences; Hungarian Academy of Sciences; Budapest Hungary
| | - Zsuzsa Majer
- Institute of Chemistry; Eötvös Loránd University; Budapest Hungary
| | - Mihály Kovács
- Department of Biochemistry; ELTE-MTA ‘Momentum’ Motor Enzymology Research Group; Eötvös Loránd University; Budapest Hungary
| | - András Micsonai
- Department of Biochemistry; MTA-ELTE NAP B Neuroimmunology Research Group; Institute of Biology; Eötvös Loránd University; Budapest Hungary
| | - József Kardos
- Department of Biochemistry; MTA-ELTE NAP B Neuroimmunology Research Group; Institute of Biology; Eötvös Loránd University; Budapest Hungary
| | - Orsolya Toke
- Laboratory for NMR Spectroscopy; Research Centre for Natural Sciences; Hungarian Academy of Sciences; Budapest Hungary
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5
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Pérez Santero S, Favretto F, Zanzoni S, Chignola R, Assfalg M, D'Onofrio M. Effects of macromolecular crowding on a small lipid binding protein probed at the single-amino acid level. Arch Biochem Biophys 2016; 606:99-110. [DOI: 10.1016/j.abb.2016.07.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 07/16/2016] [Accepted: 07/21/2016] [Indexed: 11/29/2022]
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6
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Tomaselli S, Pagano K, Boulton S, Zanzoni S, Melacini G, Molinari H, Ragona L. Lipid binding protein response to a bile acid library: a combined NMR and statistical approach. FEBS J 2015; 282:4094-113. [PMID: 26260520 DOI: 10.1111/febs.13405] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Revised: 07/20/2015] [Accepted: 08/06/2015] [Indexed: 01/23/2023]
Abstract
Primary bile acids, differing in hydroxylation pattern, are synthesized from cholesterol in the liver and, once formed, can undergo extensive enzyme-catalysed glycine/taurine conjugation, giving rise to a complex mixture, the bile acid pool. Composition and concentration of the bile acid pool may be altered in diseases, posing a general question on the response of the carrier (bile acid binding protein) to the binding of ligands with different hydrophobic and steric profiles. A collection of NMR experiments (H/D exchange, HET-SOFAST, ePHOGSY NOESY/ROESY and (15) N relaxation measurements) was thus performed on apo and five different holo proteins, to monitor the binding pocket accessibility and dynamics. The ensemble of obtained data could be rationalized by a statistical approach, based on chemical shift covariance analysis, in terms of residue-specific correlations and collective protein response to ligand binding. The results indicate that the same residues are influenced by diverse chemical stresses: ligand binding always induces silencing of motions at the protein portal with a concomitant conformational rearrangement of a network of residues, located at the protein anti-portal region. This network of amino acids, which do not belong to the binding site, forms a contiguous surface, sensing the presence of the bound lipids, with a signalling role in switching protein-membrane interactions on and off.
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Affiliation(s)
- Simona Tomaselli
- NMR Laboratory, Istituto per lo Studio delle Macromolecole (ISMAC), Milano, Italy
| | - Katiuscia Pagano
- NMR Laboratory, Istituto per lo Studio delle Macromolecole (ISMAC), Milano, Italy
| | - Stephen Boulton
- Departments of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Canada
| | | | - Giuseppe Melacini
- Departments of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Canada.,Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Canada
| | - Henriette Molinari
- NMR Laboratory, Istituto per lo Studio delle Macromolecole (ISMAC), Milano, Italy
| | - Laura Ragona
- NMR Laboratory, Istituto per lo Studio delle Macromolecole (ISMAC), Milano, Italy
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7
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Matsuoka D, Sugiyama S, Murata M, Matsuoka S. Molecular Dynamics Simulations of Heart-type Fatty Acid Binding Protein in Apo and Holo Forms, and Hydration Structure Analyses in the Binding Cavity. J Phys Chem B 2014; 119:114-27. [DOI: 10.1021/jp510384f] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Daisuke Matsuoka
- JST ERATO, Lipid Active
Structure Project, ‡Department of Chemistry, Graduate
School of Science, and §Project Research Center for Fundamental Science, Osaka University, 1-1
Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Shigeru Sugiyama
- JST ERATO, Lipid Active
Structure Project, ‡Department of Chemistry, Graduate
School of Science, and §Project Research Center for Fundamental Science, Osaka University, 1-1
Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Michio Murata
- JST ERATO, Lipid Active
Structure Project, ‡Department of Chemistry, Graduate
School of Science, and §Project Research Center for Fundamental Science, Osaka University, 1-1
Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Shigeru Matsuoka
- JST ERATO, Lipid Active
Structure Project, ‡Department of Chemistry, Graduate
School of Science, and §Project Research Center for Fundamental Science, Osaka University, 1-1
Machikaneyama, Toyonaka, Osaka 560-0043, Japan
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8
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Ragona L, Pagano K, Tomaselli S, Favretto F, Ceccon A, Zanzoni S, D'Onofrio M, Assfalg M, Molinari H. The role of dynamics in modulating ligand exchange in intracellular lipid binding proteins. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2014; 1844:1268-78. [PMID: 24768771 DOI: 10.1016/j.bbapap.2014.04.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 04/14/2014] [Accepted: 04/16/2014] [Indexed: 11/29/2022]
Abstract
Lipids are essential for many biological processes and crucial in the pathogenesis of several diseases. Intracellular lipid-binding proteins (iLBPs) provide mobile hydrophobic binding sites that allow hydrophobic or amphipathic lipid molecules to penetrate into and across aqueous layers. Thus iLBPs mediate the lipid transport within the cell and participate to a spectrum of tissue-specific pathways involved in lipid homeostasis. Structural studies have shown that iLBPs' binding sites are inaccessible from the bulk, implying that substrate binding should involve a conformational change able to produce a ligand entry portal. Many studies have been reported in the last two decades on iLBPs indicating that their dynamics play a pivotal role in regulating ligand binding and targeted release. The ensemble of reported data has not been reviewed until today. This review is thus intended to summarize and possibly generalize the results up to now described, providing a picture which could help to identify the missing notions necessary to improve our understanding of the role of dynamics in iLBPs' molecular recognition. Such notions would clarify the chemistry of lipid binding to iLBPs and set the basis for the development of new drugs.
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Affiliation(s)
- Laura Ragona
- Laboratorio NMR, Istituto per lo Studio delle Macromolecole (ISMAC), CNR, Via Bassini 15, 20133 Milano, Italy
| | - Katiuscia Pagano
- Laboratorio NMR, Istituto per lo Studio delle Macromolecole (ISMAC), CNR, Via Bassini 15, 20133 Milano, Italy
| | - Simona Tomaselli
- Laboratorio NMR, Istituto per lo Studio delle Macromolecole (ISMAC), CNR, Via Bassini 15, 20133 Milano, Italy
| | - Filippo Favretto
- Dipartimento di Biotecnologie, Università degli Studi di Verona, Strada Le Grazie 15, 37134 Verona, Italy
| | - Alberto Ceccon
- Dipartimento di Biotecnologie, Università degli Studi di Verona, Strada Le Grazie 15, 37134 Verona, Italy
| | - Serena Zanzoni
- Dipartimento di Biotecnologie, Università degli Studi di Verona, Strada Le Grazie 15, 37134 Verona, Italy
| | - Mariapina D'Onofrio
- Dipartimento di Biotecnologie, Università degli Studi di Verona, Strada Le Grazie 15, 37134 Verona, Italy
| | - Michael Assfalg
- Dipartimento di Biotecnologie, Università degli Studi di Verona, Strada Le Grazie 15, 37134 Verona, Italy
| | - Henriette Molinari
- Laboratorio NMR, Istituto per lo Studio delle Macromolecole (ISMAC), CNR, Via Bassini 15, 20133 Milano, Italy.
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9
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Bian L, Ji X. Distribution, transition and thermodynamic stability of protein conformations in the denaturant-induced unfolding of proteins. PLoS One 2014; 9:e91129. [PMID: 24603868 PMCID: PMC3948385 DOI: 10.1371/journal.pone.0091129] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Accepted: 02/09/2014] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Extensive and intensive studies on the unfolding of proteins require appropriate theoretical model and parameter to clearly illustrate the feature and characteristic of the unfolding system. Over the past several decades, four approaches have been proposed to describe the interaction between proteins and denaturants, but some ambiguity and deviations usually occur in the explanation of the experimental data. METHODOLOGY/PRINCIPAL FINDINGS In this work, a theoretical model was presented to show the dependency of the residual activity ratio of the proteins on the molar denaturant concentration. Through the characteristic unfolding parameters ki and Δmi in this model, the distribution, transition and thermodynamic stability of protein conformations during the unfolding process can be quantitatively described. This model was tested with the two-state unfolding of bovine heart cytochrome c and the three-state unfolding of hen egg white lysozyme induced by both guanidine hydrochloride and urea, the four-state unfolding of bovine carbonic anhydrase b induced by guanidine hydrochloride and the unfolding of some other proteins induced by denaturants. The results illustrated that this model could be used accurately to reveal the distribution and transition of protein conformations in the presence of different concentrations of denaturants and to evaluate the unfolding tendency and thermodynamic stability of different conformations. In most denaturant-induced unfolding of proteins, the unfolding became increasingly hard in next transition step and the proteins became more unstable as they attained next successive stable conformation. CONCLUSIONS/SIGNIFICANCE This work presents a useful method for people to study the unfolding of proteins and may be used to describe the unfolding and refolding of other biopolymers induced by denaturants, inducers, etc.
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Affiliation(s)
- Liujiao Bian
- College of Life Science, Northwest University, Xi’an, Shaanxi, China
- * E-mail:
| | - Xu Ji
- College of Life Science, Northwest University, Xi’an, Shaanxi, China
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10
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Longo DL, Di Gregorio E, Abategiovanni R, Ceccon A, Assfalg M, Molinari H, Aime S. Chemical exchange saturation transfer (CEST): an efficient tool for detecting molecular information on proteins' behaviour. Analyst 2014; 139:2687-90. [DOI: 10.1039/c4an00346b] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this communication, we report that protein remodeling processes, such as aggregation, unfolding and interaction with lipid membranes, may be investigated by magnetic resonance imaging (MRI) through the CEST mechanism.
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Affiliation(s)
- Dario Livio Longo
- Department of Molecular Biotechnologies and Health Sciences
- University of Torino
- 10126 Torino, Italy
- Institute for Biostructures and Bioimages (CNR)
- c/o Molecular Biotechnology Center
| | - Enza Di Gregorio
- Department of Molecular Biotechnologies and Health Sciences
- University of Torino
- 10126 Torino, Italy
| | - Riccardo Abategiovanni
- Department of Molecular Biotechnologies and Health Sciences
- University of Torino
- 10126 Torino, Italy
| | - Alberto Ceccon
- Department of Biotechnology
- University of Verona
- 37134 Verona, Italy
| | - Michael Assfalg
- Department of Biotechnology
- University of Verona
- 37134 Verona, Italy
| | | | - Silvio Aime
- Department of Molecular Biotechnologies and Health Sciences
- University of Torino
- 10126 Torino, Italy
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11
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Ceccon A, D'Onofrio M, Zanzoni S, Longo DL, Aime S, Molinari H, Assfalg M. NMR investigation of the equilibrium partitioning of a water-soluble bile salt protein carrier to phospholipid vesicles. Proteins 2013; 81:1776-91. [DOI: 10.1002/prot.24329] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2013] [Revised: 04/29/2013] [Accepted: 05/09/2013] [Indexed: 11/07/2022]
Affiliation(s)
- Alberto Ceccon
- Department of Biotechnology; University of Verona; 37134 Verona Italy
| | | | - Serena Zanzoni
- Department of Biotechnology; University of Verona; 37134 Verona Italy
| | - Dario Livio Longo
- Department of Molecular Biotechnologies and Health Sciences; Molecular Imaging Center, University of Torino; 10126 Torino Italy
| | - Silvio Aime
- Department of Molecular Biotechnologies and Health Sciences; Molecular Imaging Center, University of Torino; 10126 Torino Italy
| | | | - Michael Assfalg
- Department of Biotechnology; University of Verona; 37134 Verona Italy
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12
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Zanzoni S, D’Onofrio M, Molinari H, Assfalg M. Recombinant proteins incorporating short non-native extensions may display increased aggregation propensity as detected by high resolution NMR spectroscopy. Biochem Biophys Res Commun 2012; 427:677-81. [DOI: 10.1016/j.bbrc.2012.09.121] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2012] [Accepted: 09/23/2012] [Indexed: 10/27/2022]
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13
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Gustavsson M, Traaseth NJ, Karim CB, Lockamy EL, Thomas DD, Veglia G. Lipid-mediated folding/unfolding of phospholamban as a regulatory mechanism for the sarcoplasmic reticulum Ca2+-ATPase. J Mol Biol 2011; 408:755-65. [PMID: 21419777 DOI: 10.1016/j.jmb.2011.03.015] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Revised: 01/10/2011] [Accepted: 03/07/2011] [Indexed: 10/18/2022]
Abstract
The integral membrane protein complex between phospholamban (PLN) and sarcoplasmic reticulum Ca(2+)-ATPase (SERCA) regulates cardiac contractility. In the unphosphorylated form, PLN binds SERCA and inhibits Ca(2+) flux. Upon phosphorylation of PLN at Ser16, the inhibitory effect is reversed. Although structural details on both proteins are emerging from X-ray crystallography, cryo-electron microscopy, and NMR studies, the molecular mechanisms of their interactions and regulatory process are still lacking. It has been speculated that SERCA regulation depends on PLN structural transitions (order to disorder, i.e., folding/unfolding). Here, we investigated PLN conformational changes upon chemical unfolding by a combination of electron paramagnetic resonance and NMR spectroscopies, revealing that the conformational transitions involve mostly the cytoplasmic regions, with two concomitant phenomena: (1) membrane binding and folding of the amphipathic domain Ia and (2) folding/unfolding of the juxtamembrane domain Ib of PLN. Analysis of phosphorylated and unphosphorylated PLN with two phosphomimetic mutants of PLN (S16E and S16D) shows that the population of an unfolded state in domains Ia and Ib (T' state) is linearly correlated to the extent of SERCA inhibition measured by activity assays. Inhibition of SERCA is carried out by the folded ground state (T state) of the protein (PLN), while the relief of inhibition involves promotion of PLN to excited conformational states (Ser16 phosphorylated PLN). We propose that PLN population shifts (folding/unfolding) are a key regulatory mechanism for SERCA.
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Affiliation(s)
- Martin Gustavsson
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
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14
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Cogliati C, Ragona L, D'Onofrio M, Günther U, Whittaker S, Ludwig C, Tomaselli S, Assfalg M, Molinari H. Site-Specific Investigation of the Steady-State Kinetics and Dynamics of the Multistep Binding of Bile Acid Molecules to a Lipid Carrier Protein. Chemistry 2010; 16:11300-10. [DOI: 10.1002/chem.201000498] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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15
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Pedò M, D'Onofrio M, Ferranti P, Molinari H, Assfalg M. Towards the elucidation of molecular determinants of cooperativity in the liver bile acid binding protein. Proteins 2009; 77:718-31. [DOI: 10.1002/prot.22496] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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16
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Pedò M, Löhr F, D'Onofrio M, Assfalg M, Dötsch V, Molinari H. NMR studies reveal the role of biomembranes in modulating ligand binding and release by intracellular bile acid binding proteins. J Mol Biol 2009; 394:852-63. [PMID: 19836400 DOI: 10.1016/j.jmb.2009.10.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2009] [Revised: 10/05/2009] [Accepted: 10/08/2009] [Indexed: 10/20/2022]
Abstract
Bile acid molecules are transferred vectorially between basolateral and apical membranes of hepatocytes and enterocytes in the context of the enterohepatic circulation, a process regulating whole body lipid homeostasis. This work addresses the role of the cytosolic lipid binding proteins in the intracellular transfer of bile acids between different membrane compartments. We present nuclear magnetic resonance (NMR) data describing the ternary system composed of the bile acid binding protein, bile acids, and membrane mimetic systems, such as anionic liposomes. This work provides evidence that the investigated liver bile acid binding protein undergoes association with the anionic membrane and binding-induced partial unfolding. The addition of the physiological ligand to the protein-liposome mixture is capable of modulating this interaction, shifting the equilibrium towards the free folded holo protein. An ensemble of NMR titration experiments, based on nitrogen-15 protein and ligand observation, confirm that the membrane and the ligand establish competing binding equilibria, modulating the cytoplasmic permeability of bile acids. These results support a mechanism of ligand binding and release controlled by the onset of a bile salt concentration gradient within the polarized cell. The location of a specific protein region interacting with liposomes is highlighted.
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Affiliation(s)
- Massimo Pedò
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona, Italy
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