1
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Betts JW, Roth P, Pattrick CA, Southam HM, La Ragione RM, Poole RK, Schatzschneider U. Antibacterial activity of Mn(I) and Re(I) tricarbonyl complexes conjugated to a bile acid carrier molecule. Metallomics 2020; 12:1563-1575. [PMID: 32856674 DOI: 10.1039/d0mt00142b] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
A bifunctional cholic acid-bis(2-pyridylmethyl)amine (bpa) ligand featuring an amide linker was coordinated to a manganese(i) or rhenium(i) tricarbonyl moiety to give [M(bpacholamide)(CO)3] with M = Mn, Re in good yield and very high purity. Strong antibacterial activity was observed against four strains of methicillin-susceptible (MSSA) and methicillin-resistant (MRSA) Staphylococcus aureus, with minimum inhibitory concentrations (MICs) in the range of 2-3.5 μM. No difference in response was observed for the MSSA vs. MRSA strains. Activity was also independent of the nature of the metal center, as the Mn and Re complexes showed essentially identical MIC values. In contrast to some other metal carbonyl complexes, the activity seems to be unrelated to the release of carbon monoxide, as photoactivation of the Mn complex reduced the potency by a factor of 2-8. Both metal complexes were non-toxic in Galleria mellonella larvae at concentrations of up to 100× the MIC value. In vivo testing in Galleria larvae infected with MRSA/MSSA demonstrated a significant increase in overall survival rates from 46% in the control to 88% in the group treated with the metal complexes. ICP-MS analysis showed that the Mn and Re cholamide complexes are efficiently internalized by E. coli cells and do not interfere with membrane integrity, as evident from a lack of release of intracellular ATP. An increased sensitivity was observed in acrB, acrD, and mdt mutants that are defective in multidrug exporters, indicating that the compounds have an intracellular mechanism of action. Furthermore, E. coli mntP mutants defective in the gene encoding an Mn exporter were more sensitive than the wildtype, while inactivation of the regulator that controls expression of the Mn uptake proteins MntP and MntH slightly increased sensitivity to the compound. Single knockout mutants defective in genes linked to bile salt and oxidative stress response (dinF, yiaH, sodA, katE, and soxS) did not show increased sensitivity relative to the wild type. Overall, neither the cholic acid moiety nor the metal-carbonyl fragment alone appear to be responsible for the biological activity observed and thus the search for the primary intracellular target continues.
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Affiliation(s)
- Jono W Betts
- Department of Pathology and Infectious Diseases, School of Veterinary Medicine, University of Surrey, Guildford, UK
| | - Patrick Roth
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany.
| | - Calum A Pattrick
- Department of Molecular Biology and Biotechnology, The University of Sheffield, UK
| | - Hannah M Southam
- Department of Molecular Biology and Biotechnology, The University of Sheffield, UK
| | - Roberto M La Ragione
- Department of Pathology and Infectious Diseases, School of Veterinary Medicine, University of Surrey, Guildford, UK
| | - Robert K Poole
- Department of Molecular Biology and Biotechnology, The University of Sheffield, UK
| | - Ulrich Schatzschneider
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany.
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2
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Piché D, Tavernaro I, Fleddermann J, Lozano JG, Varambhia A, Maguire ML, Koch M, Ukai T, Hernández Rodríguez AJ, Jones L, Dillon F, Reyes Molina I, Mitzutani M, González Dalmau ER, Maekawa T, Nellist PD, Kraegeloh A, Grobert N. Targeted T 1 Magnetic Resonance Imaging Contrast Enhancement with Extraordinarily Small CoFe 2O 4 Nanoparticles. ACS APPLIED MATERIALS & INTERFACES 2019; 11:6724-6740. [PMID: 30688055 PMCID: PMC6385080 DOI: 10.1021/acsami.8b17162] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 01/28/2019] [Indexed: 06/09/2023]
Abstract
Extraordinarily small (2.4 nm) cobalt ferrite nanoparticles (ESCIoNs) were synthesized by a one-pot thermal decomposition approach to study their potential as magnetic resonance imaging (MRI) contrast agents. Fine size control was achieved using oleylamine alone, and annular dark-field scanning transmission electron microscopy revealed highly crystalline cubic spinel particles with atomic resolution. Ligand exchange with dimercaptosuccinic acid rendered the particles stable in physiological conditions with a hydrodynamic diameter of 12 nm. The particles displayed superparamagnetic properties and a low r2/ r1 ratio suitable for a T1 contrast agent. The particles were functionalized with bile acid, which improved biocompatibility by significant reduction of reactive oxygen species generation and is a first step toward liver-targeted T1 MRI. Our study demonstrates the potential of ESCIoNs as T1 MRI contrast agents.
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Affiliation(s)
- Dominique Piché
- Materials
Department, University of Oxford, Parks Road, Oxford OX1 3PH, England
| | - Isabella Tavernaro
- INM
- Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany
| | - Jana Fleddermann
- INM
- Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany
| | - Juan G. Lozano
- Materials
Department, University of Oxford, Parks Road, Oxford OX1 3PH, England
| | - Aakash Varambhia
- Materials
Department, University of Oxford, Parks Road, Oxford OX1 3PH, England
| | - Mahon L. Maguire
- British
Heart Foundation Experimental Magnetic Resonance Unit, Wellcome Trust Centre for Human Genetics, Roosevelt Drive, Oxford OX3 7BN, England
| | - Marcus Koch
- INM
- Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany
| | - Tomofumi Ukai
- Bio-Nano
Electronics Research Centre, Toyo University, 2100, Kujirai, Kawagoe, Saitama 350-8585, Japan
| | - Armando J. Hernández Rodríguez
- Departamento
de Imágenes por Resonancia Magnética, Cuban Neurosciences Center, Street 190 e/25 and 27, Cubanacan
Playa, Havana CP 11600, Cuba
| | - Lewys Jones
- Advanced
Microscopy Laboratory, Centre for Research
on Adaptive Nanostructures and Nanodevices (CRANN), Dublin 2, Ireland
- School of
Physics, Trinity College Dublin, Dublin 2, Ireland
| | - Frank Dillon
- Materials
Department, University of Oxford, Parks Road, Oxford OX1 3PH, England
| | - Israel Reyes Molina
- Departamento
de Imágenes por Resonancia Magnética, Cuban Neurosciences Center, Street 190 e/25 and 27, Cubanacan
Playa, Havana CP 11600, Cuba
| | - Mai Mitzutani
- Materials
Department, University of Oxford, Parks Road, Oxford OX1 3PH, England
- Department
of Material Science and Engineering, Tokyo
Institute of Technology, S8-25, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552, Japan
| | - Evelio R. González Dalmau
- Departamento
de Imágenes por Resonancia Magnética, Cuban Neurosciences Center, Street 190 e/25 and 27, Cubanacan
Playa, Havana CP 11600, Cuba
| | - Toru Maekawa
- Bio-Nano
Electronics Research Centre, Toyo University, 2100, Kujirai, Kawagoe, Saitama 350-8585, Japan
| | - Peter D. Nellist
- Materials
Department, University of Oxford, Parks Road, Oxford OX1 3PH, England
| | - Annette Kraegeloh
- INM
- Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany
| | - Nicole Grobert
- Materials
Department, University of Oxford, Parks Road, Oxford OX1 3PH, England
- Williams Advanced Engineering, Grove, Oxfordshire, OX12
0DQ, England
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3
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Brath U, Swamy SI, Veiga AX, Tung CC, Van Petegem F, Erdélyi M. Paramagnetic Ligand Tagging To Identify Protein Binding Sites. J Am Chem Soc 2015; 137:11391-8. [PMID: 26289584 PMCID: PMC4583072 DOI: 10.1021/jacs.5b06220] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
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Transient
biomolecular interactions are the cornerstones of the
cellular machinery. The identification of the binding sites for low
affinity molecular encounters is essential for the development of
high affinity pharmaceuticals from weakly binding leads but is hindered
by the lack of robust methodologies for characterization of weakly
binding complexes. We introduce a paramagnetic ligand tagging approach
that enables localization of low affinity protein–ligand binding
clefts by detection and analysis of intermolecular protein NMR pseudocontact
shifts, which are invoked by the covalent attachment of a paramagnetic
lanthanoid chelating tag to the ligand of interest. The methodology
is corroborated by identification of the low millimolar volatile anesthetic
interaction site of the calcium sensor protein calmodulin. It presents
an efficient route to binding site localization for low affinity complexes
and is applicable to rapid screening of protein–ligand systems
with varying binding affinity.
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Affiliation(s)
- Ulrika Brath
- Department of Chemistry and Molecular Biology and the Swedish NMR Centre, University of Gothenburg , SE-412 96 Gothenburg, Sweden
| | - Shashikala I Swamy
- Department of Chemistry and Molecular Biology and the Swedish NMR Centre, University of Gothenburg , SE-412 96 Gothenburg, Sweden
| | - Alberte X Veiga
- Department of Chemistry and Molecular Biology and the Swedish NMR Centre, University of Gothenburg , SE-412 96 Gothenburg, Sweden
| | - Ching-Chieh Tung
- Department of Biochemistry and Molecular Biology, University of British Columbia , Vancouver, BC V6T 1Z3, Canada
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, University of British Columbia , Vancouver, BC V6T 1Z3, Canada
| | - Máté Erdélyi
- Department of Chemistry and Molecular Biology and the Swedish NMR Centre, University of Gothenburg , SE-412 96 Gothenburg, Sweden
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4
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All-Purpose Containers? Lipid-Binding Protein - Drug Interactions. PLoS One 2015; 10:e0132096. [PMID: 26167932 PMCID: PMC4500398 DOI: 10.1371/journal.pone.0132096] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2015] [Accepted: 06/10/2015] [Indexed: 01/30/2023] Open
Abstract
The combined use of in vitro (19F-NMR) and in silico (molecular docking) procedures demonstrates the affinity of a number of human calycins (lipid-binding proteins from ileum, liver, heart, adipose tissue and epidermis, and retinol-binding protein from intestine) for different drugs (mainly steroids and vastatins). Comparative evaluations on the complexes outline some of the features relevant for interaction (non-polar character of the drugs; amino acids and water molecules in the protein calyx most often involved in binding). Dissociation constants (Ki) for drugs typically lie in the same range as Ki for natural ligands; in most instances (different proteins and docking conditions), vastatins are the strongest interactors, with atorvastatin ranking top in half of the cases. The affinity of some calycins for some of the vastatins is in the order of magnitude of the drug Cmax after systemic administration in humans. The possible biological implications of this feature are discussed in connection with drug delivery parameters (route of administration, binding to carrier proteins, distribution to, and accumulation in, human tissues).
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5
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Favretto F, Ceccon A, Zanzoni S, D'Onofrio M, Ragona L, Molinari H, Assfalg M. The unique ligand binding features of subfamily-II iLBPs with respect to bile salts and related drugs. Prostaglandins Leukot Essent Fatty Acids 2015; 95:1-10. [PMID: 25468388 DOI: 10.1016/j.plefa.2014.10.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Accepted: 10/20/2014] [Indexed: 11/28/2022]
Abstract
Intracellular lipid binding proteins (iLBPs) are a family of evolutionarily related small cytoplasmic proteins implicated in the transcellular transport of lipophilic ligands. Subfamily-II iLBPs include the liver fatty acid binding protein (L-FABP), and the ileal and the liver and ileal bile acid binding proteins (L-BABP and I-BABP). Atomic-level investigations during the past 15-20 years have delivered relevant information on bile acid binding by this protein group, revealing unique features including binding cooperativity, promiscuity, and site selectivity. Using NMR spectroscopy and other biophysical techniques, our laboratories have contributed to an understanding of the molecular determinants of some of these properties and their generality among proteins from different animal species. We focused especially on formation of heterotypic complexes, considering the mixed compositions of physiological bile acid pools. Experiments performed with synthetic bile acid derivatives showed that iLBPs could act as targets for cell-specific contrast agents and, more generally, as effective carriers of amphiphilic drugs. This review collects the major findings related to bile salt interactions with iLBPs aiming to provide keys for a deeper understanding of protein-mediated intracellular bile salt trafficking.
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Affiliation(s)
- Filippo Favretto
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, Verona 37134, Italy
| | - Alberto Ceccon
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, Verona 37134, Italy
| | - Serena Zanzoni
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, Verona 37134, Italy
| | - Mariapina D'Onofrio
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, Verona 37134, Italy
| | - Laura Ragona
- Institute for Macromolecular Studies, National Research Council, Via Bassini 15, Milan 20133, Italy
| | - Henriette Molinari
- Institute for Macromolecular Studies, National Research Council, Via Bassini 15, Milan 20133, Italy
| | - Michael Assfalg
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, Verona 37134, Italy.
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6
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7
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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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8
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Pagano K, Tomaselli S, Zanzoni S, Assfalg M, Molinari H, Ragona L. Bile acid binding protein: a versatile host of small hydrophobic ligands for applications in the fields of MRI contrast agents and bio-nanomaterials. Comput Struct Biotechnol J 2013; 6:e201303021. [PMID: 24688729 PMCID: PMC3962148 DOI: 10.5936/csbj.201303021] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Revised: 11/19/2013] [Accepted: 11/22/2013] [Indexed: 01/02/2023] Open
Abstract
During the last decade a growing amount of evidence has been obtained, supporting the role of the beta-clamshell family of intracellular lipid binding proteins (iLBPs) not only in the translocation of lipophilic molecules but also in lipid mediated signalling and metabolism. Given the central role of lipids in physiological processes, it is essential to have detailed knowledge on their interactions with cognate binding proteins. Structural and dynamical aspects of the binding mechanisms have been widely investigated by means of NMR spectroscopy, docking and molecular dynamics simulation approaches. iLBPs share a stable beta-barrel fold, delimiting an internal cavity capable of promiscuous ligand binding and display significant flexibility at the putative ligand portal. These features make this class of proteins good scaffolds to build host-guest systems for applications in nanomedicine and nanomaterials.
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Affiliation(s)
- Katiuscia Pagano
- Istituto per lo Studio delle Macromolecole, CNR, via Bassini 15, 20133 Milano, Italy
| | - Simona Tomaselli
- Istituto per lo Studio delle Macromolecole, CNR, via Bassini 15, 20133 Milano, Italy
| | - Serena Zanzoni
- 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
- Istituto per lo Studio delle Macromolecole, CNR, via Bassini 15, 20133 Milano, Italy
| | - Laura Ragona
- Istituto per lo Studio delle Macromolecole, CNR, via Bassini 15, 20133 Milano, Italy
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9
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D'Onofrio M, Gianolio E, Ceccon A, Arena F, Zanzoni S, Fushman D, Aime S, Molinari H, Assfalg M. High Relaxivity Supramolecular Adducts Between Human-Liver Fatty-Acid-Binding Protein and Amphiphilic GdIII Complexes: Structural Basis for the Design of Intracellular Targeting MRI Probes. Chemistry 2012; 18:9919-28. [DOI: 10.1002/chem.201103778] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Revised: 05/08/2012] [Indexed: 01/14/2023]
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10
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Májer F, Salomon JJ, Sharma R, Etzbach SV, Najib MNM, Keaveny R, Long A, Wang J, Ehrhardt C, Gilmer JF. New fluorescent bile acids: synthesis, chemical characterization, and disastereoselective uptake by Caco-2 cells of 3-deoxy 3-NBD-amino deoxycholic and ursodeoxycholic acid. Bioorg Med Chem 2012; 20:1767-78. [PMID: 22316556 DOI: 10.1016/j.bmc.2012.01.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Revised: 12/23/2011] [Accepted: 01/02/2012] [Indexed: 01/01/2023]
Abstract
Deoxycholic acid (DCA), a secondary bile acid (BA), and ursodeoxycholic acid (UDCA), a tertiary BA, cause opposing effects in vivo and in cell suspensions. Fluorescent analogues of DCA and UDCA could help investigate important questions about their cellular interactions and distribution. We have prepared a set of isomeric 3α- and 3β-amino analogues of UDCA and DCA and derivatised these with the discrete fluorophore, 4-nitrobenzo-2-oxa-1,3-diazol (NBD), forming the corresponding four fluorescent adducts. These absorb in the range 465-470 nm and fluoresce at approx. 535 nm. In order to determine the ability of the new fluorescent bile acids to mimic the parents, their uptake was studied using monolayers of Caco-2 cells, which are known to express multiple proteins of the organic anion-transporting peptide (OATP) subfamily of transporters. Cellular uptake was monitored over time at 4 and 37°C to distinguish between passive and active transport. All four BA analogues were taken up but in a strikingly stereo- and structure-specific manner, suggesting highly discriminatory interactions with transporter protein(s). The α-analogues of DCA and to a lesser extent UDCA were actively transported, whereas the β-analogues were not. The active transport process was saturable, with Michaelis-Menten constants for 3α-NBD DCA (5) being K(m)=42.27±12.98 μM and V(max)=2.8 ± 0.4 nmol/(mg protein*min) and for 3α-NBD UDCA (3) K(m)=28.20 ± 7.45 μM and V(max)=1.8 ± 0.2 nmol/(mg protein*min). These fluorescent bile acids are promising agents for investigating questions of bile acid biology and for detection of bile acids and related organic anion transport processes.
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Affiliation(s)
- Ferenc Májer
- School of Pharmacy and Pharmaceutical Sciences, Trinity College Dublin, Panoz Institute, Dublin 2, Ireland
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11
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Keizers PHJ, Ubbink M. Paramagnetic tagging for protein structure and dynamics analysis. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2011; 58:88-96. [PMID: 21241885 DOI: 10.1016/j.pnmrs.2010.08.001] [Citation(s) in RCA: 132] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2010] [Accepted: 08/05/2010] [Indexed: 05/18/2023]
Affiliation(s)
- Peter H J Keizers
- Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands
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12
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Chicken ileal bile-acid-binding protein: a promising target of investigation to understand binding co-operativity across the protein family. Biochem J 2009; 425:413-24. [PMID: 19874274 DOI: 10.1042/bj20091209] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Protein-bile acid interactions are crucial microscopic events at the basis of both physiological and pathological biochemical pathways. BABPs (bile-acid-binding proteins) are intracellular transporters able to bind ligands with different stoichiometry, selectivity and co-operativity. The molecular determinants and energetics of interaction are the observables that connect the microscopic to the macroscopic frameworks. The present paper addresses the study and proposes a mechanism for the multi-site interaction of bile acids with chicken I-BABP (ileal BABP) with the aim of elucidating the determinants of ligand binding in comparison with homologous proteins from different species and tissues. A thermodynamic binding model describing two independent consecutive binding sites is derived from isothermal titration calorimetry experiments and validated on the basis of both protein-observed and ligand-observed NMR titration data. It emerges that a singly bound protein is relatively abundant at low ligand/protein molar ratios assessing the absence of strong co-operativity. Both the measured energetics of binding and the distributed protein chemical-shift perturbations are in agreement with a first binding event triggering a global structural rearrangement. The enthalpic and entropic contributions associated with binding of the first ligand indicate that the interaction increases stability and order of the bound protein. The results described in the present study point to the presence of a protein scaffold which is able to establish long-range communication networks, but does not manifest positive-binding co-operativity, as observed for the human protein. We consider chicken I-BABP a suitable model to address the molecular basis for a gain-of-function on going from non-mammalian to mammalian species.
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13
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Borsi V, Luchinat C, Parigi G. Global and local mobility of apocalmodulin monitored through fast-field cycling relaxometry. Biophys J 2009; 97:1765-71. [PMID: 19751682 PMCID: PMC2749786 DOI: 10.1016/j.bpj.2009.07.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Revised: 06/27/2009] [Accepted: 07/08/2009] [Indexed: 02/03/2023] Open
Abstract
Calmodulin (CaM) is a ubiquitous eukaryotic protein with two conformationally independent domains that can bind up to two calcium ions each. In the calcium-bound state, CaM is able to regulate a vast number of cellular activities by binding to a multiplicity of target proteins in different modes. Its versatility has been ascribed to its anomalously high flexibility. The calcium-free form (apoCaM), which is the resting state of CaM in cells, is also able to functionally bind a number of protein targets, but its dynamics has received less attention. At variance with the calcium-bound form, the crystal structure of apoCaM shows a compact organization of the two domains, but NMR measurements could not detect any contact between them, thus indicating the presence of mobility in solution. The mobility of apoCaM is here investigated through protein proton relaxation rate measurements performed with a high-sensitivity fast-field cycling relaxometer. Such measurements provide direct access to the spectral density function and show that 1), the reorientation time is in agreement with a closed form of the protein; but 2), the collective order parameter is much smaller than for other well folded compact proteins, indicating that a remarkably large side-chain mobility must be present.
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Affiliation(s)
- Valentina Borsi
- Magnetic Resonance Center (CERM), University of Florence, Florence, Italy
| | - Claudio Luchinat
- Magnetic Resonance Center (CERM), University of Florence, Florence, Italy
- Department of Agricultural Biotechnology, University of Florence, Florence, Italy
| | - Giacomo Parigi
- Magnetic Resonance Center (CERM), University of Florence, Florence, Italy
- Department of Agricultural Biotechnology, University of Florence, Florence, Italy
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14
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Tomaselli S, Zanzoni S, Ragona L, Gianolio E, Aime S, Assfalg M, Molinari H. Solution Structure of the Supramolecular Adduct between a Liver Cytosolic Bile Acid Binding Protein and a Bile Acid-Based Gadolinium(III)-Chelate, a Potential Hepatospecific Magnetic Resonance Imaging Contrast Agent. J Med Chem 2008; 51:6782-92. [DOI: 10.1021/jm800820b] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Simona Tomaselli
- ISMAC-CNR, Via Bassini 15, 20133 Milano, Italy, Dipartimento Scientifico e Tecnologico, Università degli Studi di Verona, 37134 Verona, Italy, Dipartimento di Chimica, Università degli Studi di Torino, Via Pietro Giuria 7, Torino, Italy
| | - Serena Zanzoni
- ISMAC-CNR, Via Bassini 15, 20133 Milano, Italy, Dipartimento Scientifico e Tecnologico, Università degli Studi di Verona, 37134 Verona, Italy, Dipartimento di Chimica, Università degli Studi di Torino, Via Pietro Giuria 7, Torino, Italy
| | - Laura Ragona
- ISMAC-CNR, Via Bassini 15, 20133 Milano, Italy, Dipartimento Scientifico e Tecnologico, Università degli Studi di Verona, 37134 Verona, Italy, Dipartimento di Chimica, Università degli Studi di Torino, Via Pietro Giuria 7, Torino, Italy
| | - Eliana Gianolio
- ISMAC-CNR, Via Bassini 15, 20133 Milano, Italy, Dipartimento Scientifico e Tecnologico, Università degli Studi di Verona, 37134 Verona, Italy, Dipartimento di Chimica, Università degli Studi di Torino, Via Pietro Giuria 7, Torino, Italy
| | - Silvio Aime
- ISMAC-CNR, Via Bassini 15, 20133 Milano, Italy, Dipartimento Scientifico e Tecnologico, Università degli Studi di Verona, 37134 Verona, Italy, Dipartimento di Chimica, Università degli Studi di Torino, Via Pietro Giuria 7, Torino, Italy
| | - Michael Assfalg
- ISMAC-CNR, Via Bassini 15, 20133 Milano, Italy, Dipartimento Scientifico e Tecnologico, Università degli Studi di Verona, 37134 Verona, Italy, Dipartimento di Chimica, Università degli Studi di Torino, Via Pietro Giuria 7, Torino, Italy
| | - Henriette Molinari
- ISMAC-CNR, Via Bassini 15, 20133 Milano, Italy, Dipartimento Scientifico e Tecnologico, Università degli Studi di Verona, 37134 Verona, Italy, Dipartimento di Chimica, Università degli Studi di Torino, Via Pietro Giuria 7, Torino, Italy
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