1
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Gao S, Campbell JX, Oas TG, Franz KJ. Multiple Modes of Zinc Binding to Histatin 5 Revealed by Buffer-Independent Thermodynamics. Inorg Chem 2023; 62:7087-7096. [PMID: 37083393 DOI: 10.1021/acs.inorgchem.3c00608] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/22/2023]
Abstract
Histatin 5 (Hist5) is an antimicrobial peptide found in human saliva as part of the innate immune system. Hist5 can bind several metal ions in vitro, and Zn2+ has been shown to function as an inhibitory switch to regulate the peptide's biological activity against the opportunistic fungal pathogen Candida albicans in cell culture. Here, we studied Zn2+ binding to Hist5 at four temperatures from 15 to 37 °C using isothermal titration calorimetry to obtain thermodynamic parameters that were corrected for competing buffer effects. Hist5 bound Zn2+ with a buffer-dependent association constant of ∼105 M-1 and a buffer-independent association constant of ∼6 × 106 M-1 at pH 7.4 and at all temperatures tested. Zn2+ binding was both enthalpically and entropically favorable, with larger entropic contributions at 15 °C and larger enthalpic contributions at 37 °C. Additionally, the Zn:Hist5 binding stoichiometry increased from 1:1 to 2:1 as temperature increased. The enthalpy-entropy compensation and the variable stoichiometry lead us to propose a model in which the Zn-Hist5 complex exists in an equilibrium between two distinct binding modes with different Zn:Hist5 stoichiometries. The in-depth thermodynamic analysis presented herein may help illuminate the biophysical basis for Zn-dependent changes in the antifungal activity of Hist5.
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Affiliation(s)
- Sean Gao
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Joanna X Campbell
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Terrence G Oas
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Katherine J Franz
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
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2
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Guffy SL, Pulavarti SVSRK, Harrison J, Fleming D, Szyperski T, Kuhlman B. Inside-Out Design of Zinc-Binding Proteins with Non-Native Backbones. Biochemistry 2023; 62:770-781. [PMID: 36634348 PMCID: PMC9939277 DOI: 10.1021/acs.biochem.2c00595] [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] [Indexed: 01/14/2023]
Abstract
The de novo design of functional proteins requires specification of tertiary structure and incorporation of molecular binding sites. Here, we develop an inside-out design strategy in the molecular modeling program Rosetta that begins with amino acid side chains from one or two α-helices making well-defined contacts with a ligand. A full-sized protein is then built around the ligand by adding additional helices that promote the formation of a protein core and allow additional contacts with the ligand. The protocol was tested by designing 12 zinc-binding proteins, each with 4-5 helices. Four of the designs were folded and bound to zinc with equilibrium dissociation constants varying between 95 nM and 1.1 μM. The design with the tightest affinity for zinc, N12, adopts a unique conformation in the folded state as assessed with nuclear magnetic resonance (NMR) and the design model closely matches (backbone root-mean-square deviation (RMSD) < 1 Å) an AlphaFold model of the sequence. Retrospective analysis with AlphaFold suggests that the sequences of many of the failed designs did not encode the desired tertiary packing.
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Affiliation(s)
- Sharon L. Guffy
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, 27599, USA
| | | | - Joseph Harrison
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Drew Fleming
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Thomas Szyperski
- Department of Chemistry, State University of New York, Buffalo, NY, 14260, USA
| | - Brian Kuhlman
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, 27599, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, 27599, USA
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3
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Santofimia-Castaño P, Rizzuti B, Abián O, Velázquez-Campoy A, Iovanna JL, Neira JL. Amphipathic helical peptides hamper protein-protein interactions of the intrinsically disordered chromatin nuclear protein 1 (NUPR1). Biochim Biophys Acta Gen Subj 2018. [DOI: 10.1016/j.bbagen.2018.03.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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4
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On the link between conformational changes, ligand binding and heat capacity. Biochim Biophys Acta Gen Subj 2016; 1860:868-878. [DOI: 10.1016/j.bbagen.2015.10.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 10/09/2015] [Accepted: 10/10/2015] [Indexed: 10/22/2022]
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5
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Jiménez-Pardo I, González-Pastor R, Lancelot A, Claveria-Gimeno R, Velázquez-Campoy A, Abian O, Ros MB, Sierra T. Shell Cross-Linked Polymeric Micelles as Camptothecin Nanocarriers for Anti-HCV Therapy. Macromol Biosci 2015; 15:1381-91. [PMID: 26045353 DOI: 10.1002/mabi.201500094] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 05/14/2015] [Indexed: 12/26/2022]
Abstract
A suitable carrier for camptothecin to act as therapy against the hepatitis C virus is presented. The carrier relies on an amphiphilic hybrid dendritic-linear-dendritic block copolymer, derived from pluronic F127 and bis-MPA dendrons, that forms micelles in aqueous solution. The dendrons admit the incorporation of multiple photoreactive groups that allow the clean and effective preparation of covalently cross-linked polymeric micelles (CLPM), susceptible of loading hydrophilic and lipophilic molecules. Cell-uptake experiments using a newly designed fluorophore, derived from rhodamine B, demonstrate that the carrier favors the accumulation of its cargo within the cell. Furthermore, loaded with camptothecin, it is efficient in fighting against the hepatitis C virus while shows lower cytotoxicity than the free drug.
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Affiliation(s)
- Isabel Jiménez-Pardo
- Departamento de Química Orgánica, Instituto de Ciencia de Materiales de Aragón (ICMA) - Universidad de Zaragoza-CSIC, 50009, Zaragoza, Spain
| | - Rebeca González-Pastor
- Instituto de Investigaciones Sanitarias de Aragon (IIS-Aragon), 50009, Zaragoza, Spain.,Instituto de Ciencias de la Salud (IACS), 50009, Zaragoza, Spain
| | - Alexandre Lancelot
- Departamento de Química Orgánica, Instituto de Nanociencia de Aragón, Universidad de Zaragoza, 50018, Zaragoza, Spain
| | - Rafael Claveria-Gimeno
- Instituto de Investigaciones Sanitarias de Aragon (IIS-Aragon), 50009, Zaragoza, Spain.,Instituto de Ciencias de la Salud (IACS), 50009, Zaragoza, Spain.,Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas y Digestivas (CIBERehd), Barcelona, Spain.,Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Unit IQFR-CSIC-BIFI, Universidad de Zaragoza, 50018, Zaragoza, Spain
| | - Adrián Velázquez-Campoy
- Instituto de Investigaciones Sanitarias de Aragon (IIS-Aragon), 50009, Zaragoza, Spain.,Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Unit IQFR-CSIC-BIFI, Universidad de Zaragoza, 50018, Zaragoza, Spain.,Fundación ARAID, Government of Aragon, 50018, Zaragoza, Spain
| | - Olga Abian
- Instituto de Investigaciones Sanitarias de Aragon (IIS-Aragon), 50009, Zaragoza, Spain.,Instituto de Ciencias de la Salud (IACS), 50009, Zaragoza, Spain.,Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas y Digestivas (CIBERehd), Barcelona, Spain.,Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Unit IQFR-CSIC-BIFI, Universidad de Zaragoza, 50018, Zaragoza, Spain
| | - M Blanca Ros
- Departamento de Química Orgánica, Instituto de Ciencia de Materiales de Aragón (ICMA) - Universidad de Zaragoza-CSIC, 50009, Zaragoza, Spain.
| | - Teresa Sierra
- Departamento de Química Orgánica, Instituto de Ciencia de Materiales de Aragón (ICMA) - Universidad de Zaragoza-CSIC, 50009, Zaragoza, Spain.
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6
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Claveria-Gimeno R, Vega S, Grazu V, de la Fuente JM, Lanas A, Velazquez-Campoy A, Abian O. Rescuing compound bioactivity in a secondary cell-based screening by using γ-cyclodextrin as a molecular carrier. Int J Nanomedicine 2015; 10:2249-59. [PMID: 25834436 PMCID: PMC4371900 DOI: 10.2147/ijn.s79480] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
In vitro primary screening for identifying bioactive compounds (inhibitors, activators or pharmacological chaperones) against a protein target results in the discovery of lead compounds that must be tested in cell-based efficacy secondary screenings. Very often lead compounds do not succeed because of an apparent low potency in cell assays, despite an excellent performance in primary screening. Primary and secondary screenings differ significantly according to the conditions and challenges the compounds must overcome in order to interact with their intended target. Cellular internalization and intracellular metabolism are some of the difficulties the compounds must confront and different strategies can be envisaged for minimizing that problem. Using a novel screening procedure we have identified 15 compounds inhibiting the hepatitis C NS3 protease in an allosteric fashion. After characterizing biophysically the interaction with the target, some of the compounds were not able to inhibit viral replication in cell assays. In order to overcome this obstacle and potentially improve cellular internalization three of these compounds were complexed with γ-cyclodextrin. Two of them showed a five- and 16-fold activity increase, compared to their activity when delivered as free compounds in solution (while γ-cyclodextrin did not show antiviral activity by itself). The most remarkable result came from a third compound that showed no antiviral activity in cell assays when delivered free in solution, but its γ-cyclodextrin complex exhibited a 50% effective concentration of 5 μM. Thus, the antiviral activity of these compounds can be significantly improved, even completely rescued, using γ-cyclodextrin as carrier molecule.
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Affiliation(s)
- Rafael Claveria-Gimeno
- Instituto Aragonés de Ciencias de la Salud (IACS), Zaragoza, Spain
- IIS Aragón, Zaragoza, Spain
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Unit IQFR-CSIC-BIFI, Universidad de Zaragoza, Zaragoza, Spain
| | - Sonia Vega
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Unit IQFR-CSIC-BIFI, Universidad de Zaragoza, Zaragoza, Spain
| | - Valeria Grazu
- Instituto de Nanociencia de Aragon (INA), Universidad de Zaragoza, Zaragoza, Spain
| | - Jesús M de la Fuente
- Instituto de Nanociencia de Aragon (INA), Universidad de Zaragoza, Zaragoza, Spain
- Instituto de Ciencia de Materiales de Aragón (ICMA), CSIC-Universidad de Zaragoza, Zaragoza, Spain
- Institute NanoBiomedicine and Engineering, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
| | - Angel Lanas
- IIS Aragón, Zaragoza, Spain
- Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas y Digestivas (CIBERehd), Barcelona, Spain
- Servicio de Aparato Digestivo, Hospital Clínico Universitario Lozano Blesa, Zaragoza, Spain
- Department of Medicine, University of Zaragoza, Zaragoza, Spain
| | - Adrian Velazquez-Campoy
- IIS Aragón, Zaragoza, Spain
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Unit IQFR-CSIC-BIFI, Universidad de Zaragoza, Zaragoza, Spain
- Fundacion ARAID, Government of Aragon, Spain
| | - Olga Abian
- Instituto Aragonés de Ciencias de la Salud (IACS), Zaragoza, Spain
- IIS Aragón, Zaragoza, Spain
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Unit IQFR-CSIC-BIFI, Universidad de Zaragoza, Zaragoza, Spain
- Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas y Digestivas (CIBERehd), Barcelona, Spain
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7
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Vega S, Abian O, Velazquez-Campoy A. A unified framework based on the binding polynomial for characterizing biological systems by isothermal titration calorimetry. Methods 2014; 76:99-115. [PMID: 25305413 DOI: 10.1016/j.ymeth.2014.09.010] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 09/26/2014] [Accepted: 09/29/2014] [Indexed: 01/10/2023] Open
Abstract
Isothermal titration calorimetry (ITC) has become the gold-standard technique for studying binding processes due to its high precision and sensitivity, as well as its capability for the simultaneous determination of the association equilibrium constant, the binding enthalpy and the binding stoichiometry. The current widespread use of ITC for biological systems has been facilitated by technical advances and the availability of commercial calorimeters. However, the complexity of data analysis for non-standard models is one of the most significant drawbacks in ITC. Many models for studying macromolecular interactions can be found in the literature, but it looks like each biological system requires specific modeling and data analysis approaches. The aim of this article is to solve this lack of unity and provide a unified methodological framework for studying binding interactions by ITC that can be applied to any experimental system. The apparent complexity of this methodology, based on the binding polynomial, is overcome by its easy generalization to complex systems.
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Affiliation(s)
- Sonia Vega
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Unit IQFR-CSIC-BIFI, Universidad de Zaragoza, Zaragoza, Spain
| | - Olga Abian
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Unit IQFR-CSIC-BIFI, Universidad de Zaragoza, Zaragoza, Spain; Instituto Aragonés de Ciencias de la Salud (IACS), Zaragoza, Spain; IIS Aragón, Zaragoza, Spain; Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas y Digestivas (CIBERehd), Spain.
| | - Adrian Velazquez-Campoy
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Unit IQFR-CSIC-BIFI, Universidad de Zaragoza, Zaragoza, Spain; Department of Biochemistry and Molecular and Cell Biology, University of Zaragoza, Zaragoza, Spain; Fundacion ARAID, Government of Aragon, Spain.
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8
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Abian O, Vega S, Sancho J, Velazquez-Campoy A. Allosteric inhibitors of the NS3 protease from the hepatitis C virus. PLoS One 2013; 8:e69773. [PMID: 23936097 PMCID: PMC3728351 DOI: 10.1371/journal.pone.0069773] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 06/15/2013] [Indexed: 12/14/2022] Open
Abstract
The nonstructural protein 3 (NS3) from the hepatitis C virus processes the non-structural region of the viral precursor polyprotein in infected hepatic cells. The NS3 protease activity has been considered a target for drug development since its identification two decades ago. Although specific inhibitors have been approved for clinical therapy very recently, resistance-associated mutations have already been reported for those drugs, compromising their long-term efficacy. Therefore, there is an urgent need for new anti-HCV agents with low susceptibility to resistance-associated mutations. Regarding NS3 protease, two strategies have been followed: competitive inhibitors blocking the active site and allosteric inhibitors blocking the binding of the accessory viral protein NS4A. In this work we exploit the intrinsic Zn+2-regulated plasticity of the protease to identify a new type of allosteric inhibitors. In the absence of Zn+2, the NS3 protease adopts a partially-folded inactive conformation. We found ligands binding to the Zn+2-free NS3 protease, trap the inactive protein, and block the viral life cycle. The efficacy of these compounds has been confirmed in replicon cell assays. Importantly, direct calorimetric assays reveal a low impact of known resistance-associated mutations, and enzymatic assays provide a direct evidence of their inhibitory activity. They constitute new low molecular-weight scaffolds for further optimization and provide several advantages: 1) new inhibition mechanism simultaneously blocking substrate and cofactor interactions in a non-competitive fashion, appropriate for combination therapy; 2) low impact of known resistance-associated mutations; 3) inhibition of NS4A binding, thus blocking its several effects on NS3 protease.
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Affiliation(s)
- Olga Abian
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Unit IQFR-CSIC-BIFI, Universidad de Zaragoza, Zaragoza, Spain
- IIS Aragón, Instituto Aragonés de Ciencias de la Salud, Zaragoza, Spain
- Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas y Digestivas (CIBERehd), Barcelona, Spain
- * E-mail: (OA); (AVC)
| | - Sonia Vega
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Unit IQFR-CSIC-BIFI, Universidad de Zaragoza, Zaragoza, Spain
| | - Javier Sancho
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Unit IQFR-CSIC-BIFI, Universidad de Zaragoza, Zaragoza, Spain
- Department of Biochemistry and Molecular and Cell Biology, Universidad de Zaragoza, Zaragoza, Spain
| | - Adrian Velazquez-Campoy
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Unit IQFR-CSIC-BIFI, Universidad de Zaragoza, Zaragoza, Spain
- Department of Biochemistry and Molecular and Cell Biology, Universidad de Zaragoza, Zaragoza, Spain
- Fundación ARAID, Government of Aragon, Zaragoza, Spain
- * E-mail: (OA); (AVC)
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9
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Vega S, Neira JL, Marcuello C, Lostao A, Abian O, Velazquez-Campoy A. NS3 protease from hepatitis C virus: biophysical studies on an intrinsically disordered protein domain. Int J Mol Sci 2013; 14:13282-306. [PMID: 23803659 PMCID: PMC3742187 DOI: 10.3390/ijms140713282] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 06/04/2013] [Accepted: 06/13/2013] [Indexed: 12/14/2022] Open
Abstract
The nonstructural protein 3 (NS3) from the hepatitis C virus (HCV) is responsible for processing the non-structural region of the viral precursor polyprotein in infected hepatic cells. NS3 protease activity, located at the N-terminal domain, is a zinc-dependent serine protease. A zinc ion, required for the hydrolytic activity, has been considered as a structural metal ion essential for the structural integrity of the protein. In addition, NS3 interacts with another cofactor, NS4A, an accessory viral protein that induces a conformational change enhancing the hydrolytic activity. Biophysical studies on the isolated protease domain, whose behavior is similar to that of the full-length protein (e.g., catalytic activity, allosteric mechanism and susceptibility to inhibitors), suggest that a considerable global conformational change in the protein is coupled to zinc binding. Zinc binding to NS3 protease can be considered as a folding event, an extreme case of induced-fit binding. Therefore, NS3 protease is an intrinsically (partially) disordered protein with a complex conformational landscape due to its inherent plasticity and to the interaction with its different effectors. Here we summarize the results from a detailed biophysical characterization of this enzyme and present new experimental data.
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Affiliation(s)
- Sonia Vega
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Unit BIFI-IQFR (CSIC), University of Zaragoza, Zaragoza 50018, Spain; E-Mails: (S.V.); (J.L.N.)
| | - Jose L. Neira
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Unit BIFI-IQFR (CSIC), University of Zaragoza, Zaragoza 50018, Spain; E-Mails: (S.V.); (J.L.N.)
- Institute of Molecular and Cell Biology, Miguel Hernandez University, Elche (Alicante) 03202, Spain
| | - Carlos Marcuello
- Advanced Microscopy Laboratory (LMA), Institute of Nanoscience of Aragon (INA), University of Zaragoza, Zaragoza 50018, Spain; E-Mails: (C.M.); (A.L.)
| | - Anabel Lostao
- Advanced Microscopy Laboratory (LMA), Institute of Nanoscience of Aragon (INA), University of Zaragoza, Zaragoza 50018, Spain; E-Mails: (C.M.); (A.L.)
- ARAID Foundation, Government of Aragon, Zaragoza 50018, Spain
| | - Olga Abian
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Unit BIFI-IQFR (CSIC), University of Zaragoza, Zaragoza 50018, Spain; E-Mails: (S.V.); (J.L.N.)
- IIS Aragon–Aragon Health Science Institute (I+CS), Zaragoza 50009, Spain
- Network Biomedical Research Center on Hepatic and Digestive Diseases (CIBERehd), Barcelona 08036, Spain
- Authors to whom correspondence should be addressed; E-Mails: (O.A.); (A.V.-C.); Tel.: +34-976-761-000 (ext. 5417) (O.A.); +34-976-762-996 (A.V.-C.); Fax: +34-976-762-990 (O.A. & A.V.-C.)
| | - Adrian Velazquez-Campoy
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Unit BIFI-IQFR (CSIC), University of Zaragoza, Zaragoza 50018, Spain; E-Mails: (S.V.); (J.L.N.)
- ARAID Foundation, Government of Aragon, Zaragoza 50018, Spain
- Department of Biochemistry and Cellular and Molecular Biology, Faculty of Sciences, University of Zaragoza, Zaragoza 50009, Spain
- Authors to whom correspondence should be addressed; E-Mails: (O.A.); (A.V.-C.); Tel.: +34-976-761-000 (ext. 5417) (O.A.); +34-976-762-996 (A.V.-C.); Fax: +34-976-762-990 (O.A. & A.V.-C.)
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10
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Fraga H, Papaleo E, Vega S, Velazquez-Campoy A, Ventura S. Zinc induced folding is essential for TIM15 activity as an mtHsp70 chaperone. Biochim Biophys Acta Gen Subj 2013; 1830:2139-49. [DOI: 10.1016/j.bbagen.2012.10.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Revised: 09/21/2012] [Accepted: 10/03/2012] [Indexed: 11/15/2022]
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11
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Kanuru M, Raman R, Aradhyam GK. Serine protease activity of calnuc: regulation by Zn2+ and G proteins. J Biol Chem 2012. [PMID: 23195954 DOI: 10.1074/jbc.m112.382846] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The functions of calnuc, a novel Ca(2+)-binding protein with multiple structural domains and diverse interacting partners, are yet unknown. We demonstrate unknown facets of calnuc, which is a serine protease in which Ser-378 of GXSXG motif, Asp-328 of DTG motif, and His-339 form the "catalytic triad," locating the enzyme active site in the C-terminal region. Analogous to the active site of Zn(2+) carboxypeptidases, calnuc has two high affinity (K(d) ∼ 20 nm), well conserved Zn(2+)-binding sites near its N terminus, although it is inactive as a peptidase. Zn(2+) binding allosterically and negatively regulates the serine protease activity of calnuc, inhibition being caused by an "open to close" change in its conformation not seen upon Ca(2+) binding. Most strikingly, interaction with G protein α subunit completely inhibits the enzymatic activity of calnuc. We thus illustrate that G proteins and Zn(2+) act as two "keys" that control enzymatic activity of calnuc, arresting it in "locked" state. Calnuc, therefore, exists dynamically in two different forms, (i) as a Ca(2+)-binding protein in Zn(2+)-bound form and (ii) as a protease in Zn(2+)-free form, commissioning it to perform multiple functions.
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Affiliation(s)
- Madhavi Kanuru
- Department of Biotechnology, Indian Institute of Technology Madras, Chennai 600 036, India
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12
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Alaee M, Rajabi P, Sharifi Z, Farajollahi MM. Immunoreactivity assessment of hepatitis C virus NS3 protease and NS5A proteins expressed in TOPO cloning system. JOURNAL OF MICROBIOLOGY, IMMUNOLOGY, AND INFECTION = WEI MIAN YU GAN RAN ZA ZHI 2012; 47:282-91. [PMID: 23040046 DOI: 10.1016/j.jmii.2012.08.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 06/30/2012] [Accepted: 08/09/2012] [Indexed: 01/29/2023]
Abstract
BACKGROUND Hepatitis C virus (HCV) is a major cause of acute and chronic liver disease. Numerous screening assays based on the detection of immunoresponses to HCV structural and nonstructural proteins have been designed. Various studies have demonstrated genotype-specific differences in anti-HCV antibody responses to different HCV proteins. METHODS Full-length NS3 protease and N-terminally truncated NS5A were expressed using pET TOPO 102/D system. Antigenicity of the purified recombinant proteins was assessed by immunoblotting and indirect enzyme-linked immunosorbent assay (ELISA). Furthermore, anti-HCV antibody responses to the recombinant proteins were evaluated in three prevalent genotypes in Iran. RESULTS We were able to express and purify NS5A and NS3 protease using TOPO cloning system. The HCV NS3 protease and NS5A produced in BL21 Star (DE3) was immunoreactive. Our results demonstrate that NS3 protease and NS5A have good immunoreactivity, but they are not sufficient for detecting all HCV-positive sera. No significant genotype-specific differences were detected in immunoresponses to the recombinant proteins. CONCLUSION In conclusion, we successfully isolated, expressed, and purified substantial amount of HCV NS3 protease and N-terminally truncated NS5A, and used them as capturing antigens in a screening ELISA assay with high sensitivity, reproducibility, and specificity. Accordingly, it is well confirmed that TOPO cloning system can be used as a dynamic system in order to express higher amount of immunoreactive viral proteins.
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Affiliation(s)
- Mahsa Alaee
- Department of Medical Biotechnology, Faculty of Allied Medical Sciences, Tehran University of Medical Sciences, Tehran, Iran
| | - Peyman Rajabi
- Department of Medical Biotechnology, Faculty of Allied Medical Sciences, Tehran University of Medical Sciences, Tehran, Iran
| | - Zohreh Sharifi
- Blood Transfusion Research Center, High Institute for Research and Education in Transfusion Medicine, Tehran, Iran
| | - Mohammad Morad Farajollahi
- Department of Medical Biotechnology, Faculty of Allied Medical Sciences, Tehran University of Medical Sciences, Tehran, Iran.
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13
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Martinez-Julvez M, Abian O, Vega S, Medina M, Velazquez-Campoy A. Studying the allosteric energy cycle by isothermal titration calorimetry. Methods Mol Biol 2012; 796:53-70. [PMID: 22052485 DOI: 10.1007/978-1-61779-334-9_4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Isothermal titration calorimetry (ITC) is a powerful biophysical technique which allows a complete thermodynamic characterization of protein interactions with other molecules. The possibility of dissecting the Gibbs energy of interaction into its enthalpic and entropic contributions, as well as the detailed additional information experimentally accessible on the intermolecular interactions (stoichiometry, cooperativity, heat capacity changes, and coupled equilibria), make ITC a suitable technique for studying allosteric interactions in proteins. Two experimental methodologies for the characterization of allosteric heterotropic ligand interactions by ITC are described in this chapter, illustrated with two proteins with markedly different structural and functional features: a photosynthetic electron transfer protein and a drug target viral protease.
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Affiliation(s)
- Marta Martinez-Julvez
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Universidad de Zaragoza, Zaragoza, Spain.
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14
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Portillo-Téllez M, Bello M, Salcedo G, Gutiérrez G, Gómez-Vidales V, García-Hernández E. Folding and homodimerization of wheat germ agglutinin. Biophys J 2011; 101:1423-31. [PMID: 21943423 PMCID: PMC3177061 DOI: 10.1016/j.bpj.2011.07.037] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Revised: 07/18/2011] [Accepted: 07/25/2011] [Indexed: 10/17/2022] Open
Abstract
Wheat germ agglutinin (WGA) is emblematic of proteins that specialize in the recognition of carbohydrates. It was the first lectin reported to have a capacity for discriminating between normal and malignant cells. Since then, it has become a preferred model for basic research and is frequently considered in the development of biomedical and biotechnological applications. However, the molecular basis for the structural stability of this homodimeric lectin remains largely unknown, a situation that limits the rational manipulation and modification of its function. In this work we performed a thermodynamic characterization of WGA folding and self-association processes as a function of pH and temperature by using differential scanning and isothermal dilution calorimetry. WGA is monomeric at pH 2, and one of its four hevein-like domains is unfolded at room temperature. Under such conditions, the agglutinin exhibits a fully reversible thermal unfolding that consists of three two-state transitions. At higher pH values, the protein forms weak, nonobligate dimers. This behavior contrasts with that observed for the other plant lectins studied thus far, which form strong, obligate oligomers, indicating a distinctly different molecular basis for WGA function. For dimer formation, the four domains must be properly folded. Nevertheless, depending on the solution conditions, self-association may be coupled with folding of the labile domain. Therefore, dimerization may proceed as a rigid-body-like association or a folding-by-binding event. This hybrid behavior is not seen in other plant lectins. The emerging molecular picture for the WGA assembly highlights the need for a reexamination of existing ligand-binding data in the literature.
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Affiliation(s)
| | - Martiniano Bello
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, México
| | - Guillermo Salcedo
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, México, D.F., México
| | - Gabriel Gutiérrez
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, México, D.F., México
| | - Virginia Gómez-Vidales
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, México, D.F., México
| | - Enrique García-Hernández
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, México, D.F., México
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15
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Abian O, Vega S, Neira JL, Velazquez-Campoy A. Conformational stability of hepatitis C virus NS3 protease. Biophys J 2011; 99:3811-20. [PMID: 21112306 DOI: 10.1016/j.bpj.2010.10.037] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2010] [Revised: 10/22/2010] [Accepted: 10/26/2010] [Indexed: 11/17/2022] Open
Abstract
The hepatitis C virus NS3 protease is responsible for the processing of the nonstructural region of viral precursor polyprotein in infected hepatic cells. NS3 has been considered a target for drug discovery for a long time. NS3 is a zinc-dependent serine protease. However, the zinc ion is not involved in the catalytic mechanism, because it is bound far away from the active site. Thus, zinc is essential for the structural integrity of the protein and it is considered to have a structural role. The first thermodynamic study on the conformational equilibrium and stability of NS3 and the effect of zinc on such equilibrium is presented here. In agreement with a previous calorimetric study on the binding of zinc to NS3, the global unfolding heat capacity is dominated by the zinc dissociation step, suggesting that the binding of zinc induces a significant structural rearrangement of the protein. In addition, contrary to other homologous zinc-dependent proteases, the zinc-free NS3 protease is not completely unstructured. It is apparent that the conformational landscape of hepatitis C virus NS3 protease is fairly complex due to its intrinsic plasticity, and to the interactions with its different effectors (zinc and the accessory viral protein NS4A) and their modulation of the population of the different conformational states.
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Affiliation(s)
- Olga Abian
- Institute of Biocomputation and Physics of Complex Systems, Universidad de Zaragoza, Zaragoza, Spain.
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16
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Falconer RJ, Collins BM. Survey of the year 2009: applications of isothermal titration calorimetry. J Mol Recognit 2010; 24:1-16. [DOI: 10.1002/jmr.1073] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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17
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Taneva SG, Moro F, Velázquez-Campoy A, Muga A. Energetics of nucleotide-induced DnaK conformational states. Biochemistry 2010; 49:1338-45. [PMID: 20078127 DOI: 10.1021/bi901847q] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Hsp70 chaperones are molecular switches that use the free energy of ATP binding and hydrolysis to modulate their affinity for protein substrates and, most likely, to remodel non-native interactions allowing proper substrate folding. By means of isothermal titration calorimetry, we have measured the thermodynamics of ATP and ADP binding to (i) wild-type DnaK, the main bacterial Hsp70; (ii) two single-point mutants, DnaK(T199A), which lacks ATPase activity but maintains conformational changes similar to those observed in the wild-type protein, and DnaK(R151A), defective in interdomain communication; and iii) two deletion mutants, the isolated nucleotide binding domain (K-NBD) and a DeltaLid construct [DnaK(1-507)]. At 25 degrees C, ATP binding to DnaK results in a fast endothermic and a slow exothermic process due to ATP hydrolysis. We demonstrate that the endothermic event is due to the allosteric coupling between ATP binding to the nucleotide binding domain and the conformational rearrangement of the substrate binding domain. The interpretation of our data is compatible with domain docking upon ATP binding and shows that this conformational change carries an energy penalty of ca. 1 kcal/mol. The conformational energy stored in the ATP-bound DnaK state, together with the free energy of ATP hydrolysis, can be used in remodeling bound substrates.
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Affiliation(s)
- Stefka G Taneva
- Unidad de Biofsica (CSIC/UPV-EHU) y Departamento de Bioquímica y Biología Molecular, Facultad de Ciencia y Tecnología, Universidad del País Vasco, Apartado 644, 48080 Bilbao, Spain
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