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Rizzuti B, Abian O, Velazquez-Campoy A, Neira JL. Conformational Stability of the N-Terminal Region of MDM2. Molecules 2023; 28:7578. [PMID: 38005300 PMCID: PMC10673428 DOI: 10.3390/molecules28227578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 11/07/2023] [Accepted: 11/08/2023] [Indexed: 11/26/2023] Open
Abstract
MDM2 is an E3 ubiquitin ligase which is crucial for the degradation and inhibition of the key tumor-suppressor protein p53. In this work, we explored the stability and the conformational features of the N-terminal region of MDM2 (N-MDM2), through which it binds to the p53 protein as well as other protein partners. The isolated domain possessed a native-like conformational stability in a narrow pH range (7.0 to 10.0), as shown by intrinsic and 8-anilinonapthalene-1-sulfonic acid (ANS) fluorescence, far-UV circular dichroism (CD), and size exclusion chromatography (SEC). Guanidinium chloride (GdmCl) denaturation followed by intrinsic and ANS fluorescence, far-UV CD and SEC at physiological pH, and differential scanning calorimetry (DSC) and thermo-fluorescence experiments showed that (i) the conformational stability of isolated N-MDM2 was very low; and (ii) unfolding occurred through the presence of several intermediates. The presence of a hierarchy in the unfolding intermediates was also evidenced through DSC and by simulating the unfolding process with the help of computational techniques based on constraint network analysis (CNA). We propose that the low stability of this protein is related to its inherent flexibility and its ability to interact with several molecular partners through different routes.
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Affiliation(s)
- Bruno Rizzuti
- CNR-NANOTEC, SS Rende (CS), Department of Physics, University of Calabria, 87036 Rende, Italy
- Instituto de Biocomputación y Física de Sistemas Complejos (BIFI)—Unidad mixta GBsC-CSIC-BIFI, Universidad de Zaragoza, 50018 Zaragoza, Spain; (O.A.); (A.V.-C.)
| | - Olga Abian
- Instituto de Biocomputación y Física de Sistemas Complejos (BIFI)—Unidad mixta GBsC-CSIC-BIFI, Universidad de Zaragoza, 50018 Zaragoza, Spain; (O.A.); (A.V.-C.)
- Instituto de Investigación Sanitaria Aragón (IIS Aragón), 50009 Zaragoza, Spain
- Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas y Digestivas (CIBERehd), 28029 Madrid, Spain
- Departamento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, 50009 Zaragoza, Spain
| | - Adrián Velazquez-Campoy
- Instituto de Biocomputación y Física de Sistemas Complejos (BIFI)—Unidad mixta GBsC-CSIC-BIFI, Universidad de Zaragoza, 50018 Zaragoza, Spain; (O.A.); (A.V.-C.)
- Instituto de Investigación Sanitaria Aragón (IIS Aragón), 50009 Zaragoza, Spain
- Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas y Digestivas (CIBERehd), 28029 Madrid, Spain
- Departamento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, 50009 Zaragoza, Spain
| | - José L. Neira
- Instituto de Biocomputación y Física de Sistemas Complejos (BIFI)—Unidad mixta GBsC-CSIC-BIFI, Universidad de Zaragoza, 50018 Zaragoza, Spain; (O.A.); (A.V.-C.)
- Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDIBE), Universidad Miguel Hernández, 03202 Elche, Spain
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2
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Delfing BM, Laracuente XE, Olson A, Foreman KW, Paige M, Kehn-Hall K, Lockhart C, Klimov DK. Binding of viral nuclear localization signal peptides to importin-α nuclear transport protein. Biophys J 2023; 122:3476-3488. [PMID: 37542371 PMCID: PMC10502480 DOI: 10.1016/j.bpj.2023.07.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 05/23/2023] [Accepted: 07/27/2023] [Indexed: 08/06/2023] Open
Abstract
Using all-atom replica-exchange molecular dynamics simulations, we mapped the mechanisms of binding of the nuclear localization signal (NLS) sequence from Venezuelan equine encephalitis virus (VEEV) capsid protein to importin-α (impα) transport protein. Our objective was to identify the VEEV NLS sequence fragment that confers native, experimentally resolved binding to impα as well as to study associated binding energetics and conformational ensembles. The two selected VEEV NLS peptide fragments, KKPK and KKPKKE, show strikingly different binding mechanisms. The minNLS peptide KKPK binds non-natively and nonspecifically by adopting five diverse conformational clusters with low similarity to the x-ray structure 3VE6 of NLS-impα complex. Despite the prevalence of non-native interactions, the minNLS peptide still largely binds to the impα major NLS binding site. In contrast, the coreNLS peptide KKPKKE binds specifically and natively, adopting a largely homogeneous binding ensemble with a dominant, highly native-like conformational cluster. The coreNLS peptide retains most of native binding interactions, including π-cation contacts and a tryptophan cage. While KKPK binding is governed by a complex multistate free energy landscape featuring transitions between multiple binding poses, the coreNLS peptide free energy map is simple, exhibiting a single dominant native-like bound basin. We argue that the origin of the coreNLS peptide binding specificity is several electrostatic interactions formed by the two C-terminal amino acids, Lys10 and Glu11, with impα. The coreNLS sequence is then sufficient for native binding, but none of the amino acids flanking minNLS, including Lys10 and Glu11, are strictly necessary for the native pose. Our analyses indicate that the VEEV coreNLS sequence is virtually unique among human and viral proteins interacting with impα making it a potential target for VEEV-specific inhibitors.
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Affiliation(s)
- Bryan M Delfing
- School of Systems Biology, George Mason University, Manassas, Virginia
| | | | - Audrey Olson
- School of Systems Biology, George Mason University, Manassas, Virginia
| | - Kenneth W Foreman
- Department of Chemistry and Biochemistry, George Mason University, Manassas, Virginia
| | - Mikell Paige
- Department of Chemistry and Biochemistry, George Mason University, Manassas, Virginia
| | - Kylene Kehn-Hall
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, Virginia; Center for Emerging, Zoonotic, and Arthropod-borne Pathogens, Virginia Polytechnic Institute and State University, Blacksburg, Virginia
| | | | - Dmitri K Klimov
- School of Systems Biology, George Mason University, Manassas, Virginia.
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3
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Del ng BM, Olson A, Laracuente XE, Foreman KW, Paige M, Kehn-Hall K, Lockhart C, Klimov DK. Binding of Venezuelan Equine Encephalitis Virus Inhibitors to Importin-α Receptors Explored with All-Atom Replica Exchange Molecular Dynamics. J Phys Chem B 2023; 127:3175-3186. [PMID: 37001021 PMCID: PMC10358320 DOI: 10.1021/acs.jpcb.3c00429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023]
Abstract
Although Venezuelan equine encephalitis virus (VEEV) is a life-threatening pathogen with a capacity for epidemic outbreaks, there are no FDA-approved VEEV antivirals for humans. VEEV cytotoxicity is partially attributed to the formation of a tetrameric complex between the VEEV capsid protein, the nuclear import proteins importin-α and importin-β, and the nuclear export protein CRM1, which together block trafficking through the nuclear pore complex. Experimental studies have identified small molecules from the CL6662 scaffold as potential inhibitors of the viral nuclear localization signal (NLS) sequence binding to importin-α. However, little is known about the molecular mechanism of CL6662 inhibition. To address this issue, we employed all-atom replica exchange molecular dynamics simulations to probe, in atomistic detail, the binding mechanism of CL6662 ligands to importin-α. Three ligands, including G281-1485 and two congeners with varying hydrophobicities, were considered. We investigated the distribution of ligand binding poses, their locations, and ligand specificities measured by the strength of binding interactions. We found that G281-1485 binds nonspecifically without forming well-defined binding poses throughout the NLS binding site. Binding of the less hydrophobic congener becomes strongly on-target with respect to the NLS binding site but remains nonspecific. However, a more hydrophobic congener is a strongly specific binder and the only ligand out of three to form a well-defined binding pose, while partially overlapping with the NLS binding site. On the basis of free energy estimates, we argue that all three ligands weakly compete with the viral NLS sequence for binding to importin-α in an apparent compromise to preserve host NLS binding. We further show that all-atom replica exchange binding simulations are a viable tool for studying ligands binding nonspecifically without forming well-defined binding poses.
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Affiliation(s)
- Bryan M. Del ng
- School of Systems Biology, George Mason University, Manassas, VA 20110, USA
| | - Audrey Olson
- School of Systems Biology, George Mason University, Manassas, VA 20110, USA
| | | | - Kenneth W. Foreman
- Department of Chemistry and Biochemistry, George Mason University, Manassas, VA 20110, USA
| | - Mikell Paige
- Department of Chemistry and Biochemistry, George Mason University, Manassas, VA 20110, USA
| | - Kylene Kehn-Hall
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
- Center for Emerging, Zoonotic, and Arthropod-borne Pathogens, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | | | - Dmitri K. Klimov
- School of Systems Biology, George Mason University, Manassas, VA 20110, USA
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4
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Rizzuti B, Iovanna JL, Neira JL. Deciphering the Binding of the Nuclear Localization Sequence of Myc Protein to the Nuclear Carrier Importin α3. Int J Mol Sci 2022; 23:ijms232315333. [PMID: 36499669 PMCID: PMC9739371 DOI: 10.3390/ijms232315333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 11/29/2022] [Accepted: 12/02/2022] [Indexed: 12/12/2022] Open
Abstract
The oncoprotein Myc is a transcription factor regulating global gene expression and modulating cell proliferation, apoptosis, and metabolism. Myc has a nuclear localization sequence (NLS) comprising residues Pro320 to Asp328, to allow for nuclear translocation. We designed a peptide comprising such region and the flanking residues (Ala310-Asn339), NLS-Myc, to study, in vitro and in silico, the ability to bind importin α3 (Impα3) and its truncated species (ΔImpα3) depleted of the importin binding domain (IBB), by using fluorescence, circular dichroism (CD), biolayer interferometry (BLI), nuclear magnetic resonance (NMR), and molecular simulations. NLS-Myc interacted with both importin species, with affinity constants of ~0.5 µM (for Impα3) and ~60 nM (for ΔImpα3), as measured by BLI. The molecular simulations predicted that the anchoring of NLS-Myc took place in the major binding site of Impα3 for the NLS of cargo proteins. Besides clarifying the conformational behavior of the isolated NLS of Myc in solution, our results identified some unique properties in the binding of this localization sequence to the nuclear carrier Impα3, such as a difference in the kinetics of its release mechanism depending on the presence or absence of the IBB domain.
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Affiliation(s)
- Bruno Rizzuti
- CNR-NANOTEC, SS Rende (CS), Department of Physics, University of Calabria, 87036 Rende, Italy
- Instituto de Biocomputación y Física de Sistemas Complejos–Unidad Mixta GBsC-CSIC-BIFI, Universidad de Zaragoza, 50018 Zaragoza, Spain
- Correspondence: (B.R.); (J.L.N.)
| | - Juan L. Iovanna
- Centre de Recherche en Cancérologie de Marseille (CRCM), INSERM U1068, CNRS UMR 7258, Institut Paoli-Calmettes, Aix-Marseille Université, 13288 Marseille, France
| | - José L. Neira
- Instituto de Biocomputación y Física de Sistemas Complejos–Unidad Mixta GBsC-CSIC-BIFI, Universidad de Zaragoza, 50018 Zaragoza, Spain
- Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDIBE), Universidad Miguel Hernández, 03202 Elche, Spain
- Correspondence: (B.R.); (J.L.N.)
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5
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Florio TJ, Lokareddy RK, Yeggoni DP, Sankhala RS, Ott CA, Gillilan RE, Cingolani G. Differential recognition of canonical NF-κB dimers by Importin α3. Nat Commun 2022; 13:1207. [PMID: 35260573 PMCID: PMC8904830 DOI: 10.1038/s41467-022-28846-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 02/11/2022] [Indexed: 11/09/2022] Open
Abstract
Nuclear translocation of the p50/p65 heterodimer is essential for NF-κB signaling. In unstimulated cells, p50/p65 is retained by the inhibitor IκBα in the cytoplasm that masks the p65-nuclear localization sequence (NLS). Upon activation, p50/p65 is translocated into the nucleus by the adapter importin α3 and the receptor importin β. Here, we describe a bipartite NLS in p50/p65, analogous to nucleoplasmin NLS but exposed in trans. Importin α3 accommodates the p50- and p65-NLSs at the major and minor NLS-binding pockets, respectively. The p50-NLS is the predominant binding determinant, while the p65-NLS induces a conformational change in the Armadillo 7 of importin α3 that stabilizes a helical conformation of the p65-NLS. Neither conformational change was observed for importin α1, which makes fewer bonds with the p50/p65 NLSs, explaining the preference for α3. We propose that importin α3 discriminates between the transcriptionally active p50/p65 heterodimer and p50/p50 and p65/65 homodimers, ensuring fidelity in NF-κB signaling. Nuclear translocation of the p50/p65 heterodimer is essential for NF-κB signaling. Here, the authors identify a bipartite Nuclear Localization Signal in the NF-κB p50/p65 heterodimer that is recognized with high affinity by importin α3.
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Affiliation(s)
- Tyler J Florio
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA, 19107, USA
| | - Ravi K Lokareddy
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA, 19107, USA
| | - Daniel P Yeggoni
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA, 19107, USA
| | - Rajeshwer S Sankhala
- Center of Infectious Disease Research, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Connor A Ott
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA, 19107, USA
| | - Richard E Gillilan
- Macromolecular Diffraction Facility, Cornell High Energy Synchrotron Source (MacCHESS), Cornell University, 161 Synchrotron Drive, Ithaca, NY, 14853, USA
| | - Gino Cingolani
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA, 19107, USA.
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6
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Neira JL, Araujo-Abad S, Cámara-Artigas A, Rizzuti B, Abian O, Giudici AM, Velazquez-Campoy A, de Juan Romero C. Biochemical and biophysical characterization of PADI4 supports its involvement in cancer. Arch Biochem Biophys 2022; 717:109125. [DOI: 10.1016/j.abb.2022.109125] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 01/14/2022] [Accepted: 01/17/2022] [Indexed: 12/12/2022]
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7
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Bonucci A, Palomino-Schätzlein M, Malo de Molina P, Arbe A, Pierattelli R, Rizzuti B, Iovanna JL, Neira JL. Crowding Effects on the Structure and Dynamics of the Intrinsically Disordered Nuclear Chromatin Protein NUPR1. Front Mol Biosci 2021; 8:684622. [PMID: 34291085 PMCID: PMC8287036 DOI: 10.3389/fmolb.2021.684622] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 06/22/2021] [Indexed: 01/02/2023] Open
Abstract
The intracellular environment is crowded with macromolecules, including sugars, proteins and nucleic acids. In the cytoplasm, crowding effects are capable of excluding up to 40% of the volume available to any macromolecule when compared to dilute conditions. NUPR1 is an intrinsically disordered protein (IDP) involved in cell-cycle regulation, stress-cell response, apoptosis processes, DNA binding and repair, chromatin remodeling and transcription. Simulations of molecular crowding predict that IDPs can adopt compact states, as well as more extended conformations under crowding conditions. In this work, we analyzed the conformation and dynamics of NUPR1 in the presence of two synthetic polymers, Ficoll-70 and Dextran-40, which mimic crowding effects in the cells, at two different concentrations (50 and 150 mg/ml). The study was carried out by using a multi-spectroscopic approach, including: site-directed spin labelling electron paramagnetic resonance spectroscopy (SDSL-EPR), nuclear magnetic resonance spectroscopy (NMR), circular dichroism (CD), small angle X-ray scattering (SAXS) and dynamic light scattering (DLS). SDSL-EPR spectra of two spin-labelled mutants indicate that there was binding with the crowders and that the local dynamics of the C and N termini of NUPR1 were partially affected by the crowders. However, the overall disordered nature of NUPR1 did not change substantially in the presence of the crowders, as shown by circular dichroism CD and NMR, and further confirmed by EPR. The changes in the dynamics of the paramagnetic probes appear to be related to preferred local conformations and thus crowding agents partially affect some specific regions, further pinpointing that NUPR1 flexibility has a key physiological role in its activity.
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Affiliation(s)
- Alessio Bonucci
- CERM & Department of Chemistry "Ugo Schiff", University of Florence, Sesto Fiorentino (Florence), Italy
| | | | - Paula Malo de Molina
- Centro de Física de Materiales (CFM), CSIC-UPV/EHU, San Sebastián, Spain.,IKERBASQUE-Basque Foundation for Science, Bilbao, Spain
| | - Arantxa Arbe
- Centro de Física de Materiales (CFM), CSIC-UPV/EHU, San Sebastián, Spain
| | - Roberta Pierattelli
- CERM & Department of Chemistry "Ugo Schiff", University of Florence, Sesto Fiorentino (Florence), Italy
| | - Bruno Rizzuti
- CNR-NANOTEC, Licryl-UOS Cosenza and CEMIF.Cal, Department of Physics, University of Calabria, Rende, Italy.,Instituto de Biocomputación y Física de Sistemas Complejos (BIFI), Joint Units IQFR-CSIC-BIFI and GBsC-CSIC-BIFI, Universidad de Zaragoza, Zaragoza, Spain
| | - Juan L Iovanna
- Centre de Recherche en Cancérologie de Marseille (CRCM), INSERM U1068, CNRS UMR 7258, Aix-Marseille Université and Institut Paoli-Calmettes, Parc Scientifique et Technologique de Luminy, Marseille, France
| | - José L Neira
- Instituto de Biocomputación y Física de Sistemas Complejos (BIFI), Joint Units IQFR-CSIC-BIFI and GBsC-CSIC-BIFI, Universidad de Zaragoza, Zaragoza, Spain.,IDIBE, Universidad Miguel Hernández, Elche (Alicante), Spain
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8
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Neira JL, Cámara-Artigas A, Hernández-Cifre JG, Ortore MG. The Histidine Phosphocarrier Kinase/Phosphorylase from Bacillus Subtilis Is an Oligomer in Solution with a High Thermal Stability. Int J Mol Sci 2021; 22:3231. [PMID: 33810099 PMCID: PMC8004850 DOI: 10.3390/ijms22063231] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 03/12/2021] [Accepted: 03/15/2021] [Indexed: 01/25/2023] Open
Abstract
The histidine phosphocarrier protein (HPr) kinase/phosphorylase (HPrK/P) modulates the phosphorylation state of the HPr protein, and it is involved in the use of carbon sources by Gram-positive bacteria. Its X-ray structure, as concluded from crystals of proteins from several species, is a hexamer; however, there are no studies about its conformational stability, and how its structure is modified by the pH. We have embarked on the conformational characterization of HPrK/P of Bacillus subtilis (bsHPrK/P) in solution by using several spectroscopic (namely, fluorescence and circular dichroism (CD)) and biophysical techniques (namely, small-angle X-ray-scattering (SAXS) and dynamic light-scattering (DLS)). bsHPrK/P was mainly a hexamer in solution at pH 7.0, in the presence of phosphate. The protein had a high conformational stability, with an apparent thermal denaturation midpoint of ~70 °C, at pH 7.0, as monitored by fluorescence and CD. The protein was very pH-sensitive, precipitated between pH 3.5 and 6.5; below pH 3.5, it had a molten-globule-like conformation; and it acquired a native-like structure in a narrow pH range (between pH 7.0 and 8.0). Guanidinium hydrochloride (GdmCl) denaturation occurred through an oligomeric intermediate. On the other hand, urea denaturation occurred as a single transition, in the range of concentrations between 1.8 and 18 µM, as detected by far-UV CD and fluorescence.
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Affiliation(s)
- José L. Neira
- IDIBE, Universidad Miguel Hernández, 03202 Alicante, Spain
- Instituto de Biocomputación y Física de Sistemas Complejos, Joint Units IQFR-CSIC-BIFI, and GBsC-CSIC-BIFI, Universidad de Zaragoza, 50009 Zaragoza, Spain
| | - Ana Cámara-Artigas
- Departamento de Química y Física, Research Center CIAIMBITAL, Universidad de Almería- ceiA3, 04120 Almería, Spain;
| | - José Ginés Hernández-Cifre
- Departamento de Química Física, Facultad de Química, Campus de Espinardo, Universidad de Murcia, 30100 Murcia, Spain;
| | - María Grazia Ortore
- Dipartimento DiSVA, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy;
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Neira JL, Vega S, Martínez-Rodríguez S, Velázquez-Campoy A. The isolated GTPase-activating-protein-related domain of neurofibromin-1 has a low conformational stability in solution. Arch Biochem Biophys 2021; 700:108767. [PMID: 33476564 DOI: 10.1016/j.abb.2021.108767] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 01/07/2021] [Accepted: 01/11/2021] [Indexed: 11/28/2022]
Abstract
Neurofibromin-1 (NF1) is a large, multidomain tumour suppressor encoded by the NF1 gene. The gene is mutated in neurofibromatosis type I, a disease characterized by malignant tumours of the nervous system and benign neurofibromas. The best-known activity of NF1 is the down-regulation of the mitogen-activated protein kinase pathway via its three-hundred-residue-long GTPase-activating protein (GAP) domain (the so-called GAP-related domain (NF1-GRD)). The NF1-GRD stimulates Ras GTPase activity in turning off signalling. Despite this activity, NF1-GRD has been demonstrated to bind to other different proteins, such as SPRED1 or MC1R. We have embarked on the biophysical and conformational characterization of NF1-GRD in solution by using several spectroscopic (namely fluorescence and circular dichroism (CD)) and biophysical techniques (namely size exclusion chromatography (SEC) and differential scanning calorimetry (DSC)). This biophysical characterization is crucial in deciphering NF1-GRD interactome and in finding biochemical features, modulating possible protein interactions. The native-like structure of NF1-GRD (as monitored by intrinsic fluorescence and far-UV CD) was strongly pH-dependent showing a pH-titration causing a substantial increase in its helicity. NF1-GRD had a low conformational stability, as concluded from DSC experiments and thermal denaturations followed by intrinsic and ANS fluorescence, and CD. Chemical denaturations showed that NF1-GRD unfolded through an intermediate which has a substantial amount of solvent-exposed hydrophobic patches.
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Affiliation(s)
- José L Neira
- IDIBE, Universidad Miguel Hernández, 03202, Elche, Alicante, Spain; Instituto de Biocomputación y Física de Sistemas Complejos, Joint Units IQFR-CSIC-BIFI, and GBsC-CSIC-BIFI, Universidad de Zaragoza, 50009, Zaragoza, Spain.
| | - Sonia Vega
- Instituto de Biocomputación y Física de Sistemas Complejos, Joint Units IQFR-CSIC-BIFI, and GBsC-CSIC-BIFI, Universidad de Zaragoza, 50009, Zaragoza, Spain
| | - Sergio Martínez-Rodríguez
- Laboratorio de Estudios Cristalográficos, CSIC, 18100, Armilla, Granada, Spain; Dpto. Bioquímica y Biología Molecular III e Inmunología, Facultad de Medicina, Universidad de Granada, 18071, Granada, Spain.
| | - Adrián Velázquez-Campoy
- Instituto de Biocomputación y Física de Sistemas Complejos, Joint Units IQFR-CSIC-BIFI, and GBsC-CSIC-BIFI, Universidad de Zaragoza, 50009, Zaragoza, Spain; Instituto de Investigación Sanitaria Aragón (IIS Aragón), 50009, Zaragoza, Spain; Fundación ARAID, Government of Aragón, 50009, Zaragoza, Spain; Departamento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, 50009, Zaragoza, Spain; Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas y Digestivas (CIBERehd), 28006, Madrid, Spain
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10
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Neira JL, Rizzuti B, Jiménez-Alesanco A, Abián O, Velázquez-Campoy A, Iovanna JL. The Paralogue of the Intrinsically Disordered Nuclear Protein 1 Has a Nuclear Localization Sequence that Binds to Human Importin α3. Int J Mol Sci 2020; 21:ijms21197428. [PMID: 33050086 PMCID: PMC7583046 DOI: 10.3390/ijms21197428] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Revised: 09/28/2020] [Accepted: 10/03/2020] [Indexed: 02/07/2023] Open
Abstract
Numerous carrier proteins intervene in protein transport from the cytoplasm to the nucleus in eukaryotic cells. One of those is importin α, with several human isoforms; among them, importin α3 (Impα3) features a particularly high flexibility. The protein NUPR1L is an intrinsically disordered protein (IDP), evolved as a paralogue of nuclear protein 1 (NUPR1), which is involved in chromatin remodeling and DNA repair. It is predicted that NUPR1L has a nuclear localization sequence (NLS) from residues Arg51 to Gln74, in order to allow for nuclear translocation. We studied in this work the ability of intact NUPR1L to bind Impα3 and its depleted species, ∆Impα3, without the importin binding domain (IBB), using fluorescence, isothermal titration calorimetry (ITC), circular dichroism (CD), nuclear magnetic resonance (NMR), and molecular docking techniques. Furthermore, the binding of the peptide matching the isolated NLS region of NUPR1L (NLS-NUPR1L) was also studied using the same methods. Our results show that NUPR1L was bound to Imp α3 with a low micromolar affinity (~5 μM). Furthermore, a similar affinity value was observed for the binding of NLS-NUPR1L. These findings indicate that the NLS region, which was unfolded in isolation in solution, was essentially responsible for the binding of NUPR1L to both importin species. This result was also confirmed by our in silico modeling. The binding reaction of NLS-NUPR1L to ∆Impα3 showed a larger affinity (i.e., lower dissociation constant) compared with that of Impα3, confirming that the IBB could act as an auto-inhibition region of Impα3. Taken together, our findings pinpoint the theoretical predictions of the NLS region in NUPR1L and, more importantly, suggest that this IDP relies on an importin for its nuclear translocation.
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Affiliation(s)
- José L. Neira
- IDIBE, Universidad Miguel Hernández, 03202 Elche (Alicante), Spain
- Instituto de Biocomputación y Física de Sistemas Complejos, Joint Units IQFR-CSIC-BIFI, and GBsC-CSIC-BIFI, Universidad de Zaragoza, 50009 Zaragoza, Spain; (A.J.-A.); (O.A.); (A.V.-C.)
- Correspondence: (J.L.N.); (J.L.I.); Tel.: +34-966-65-8475 (J.L.N.); +33(0)491-82-8803 (J.L.I.)
| | - Bruno Rizzuti
- CNR-NANOTEC, Licryl-UOS Cosenza and CEMIF.Cal, Department of Physics, University of Calabria, Via P. Bucci, Cubo 31 C, Arcavacata di Rende, 87036 Cosenza, Italy;
| | - Ana Jiménez-Alesanco
- Instituto de Biocomputación y Física de Sistemas Complejos, Joint Units IQFR-CSIC-BIFI, and GBsC-CSIC-BIFI, Universidad de Zaragoza, 50009 Zaragoza, Spain; (A.J.-A.); (O.A.); (A.V.-C.)
| | - Olga Abián
- Instituto de Biocomputación y Física de Sistemas Complejos, Joint Units IQFR-CSIC-BIFI, and GBsC-CSIC-BIFI, Universidad de Zaragoza, 50009 Zaragoza, Spain; (A.J.-A.); (O.A.); (A.V.-C.)
- Instituto de Investigación Sanitaria Aragón (IIS Aragón), 50009 Zaragoza, Spain
- Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas y Digestivas (CIBERehd), 28029 Madrid, Spain
- Departamento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, 50009 Zaragoza, Spain
- Instituto Aragonés de Ciencias de la Salud (IACS), 50009 Zaragoza, Spain
| | - Adrián Velázquez-Campoy
- Instituto de Biocomputación y Física de Sistemas Complejos, Joint Units IQFR-CSIC-BIFI, and GBsC-CSIC-BIFI, Universidad de Zaragoza, 50009 Zaragoza, Spain; (A.J.-A.); (O.A.); (A.V.-C.)
- Instituto de Investigación Sanitaria Aragón (IIS Aragón), 50009 Zaragoza, Spain
- Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas y Digestivas (CIBERehd), 28029 Madrid, Spain
- Departamento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, 50009 Zaragoza, Spain
- Fundacion ARAID, Gobierno de Aragon, 50009 Zaragoza, Spain
| | - Juan L. Iovanna
- Centre de Recherche en Cancérologie de Marseille (CRCM), INSERM U1068, CNRS UMR 7258, Aix-Marseille Université and Institut Paoli-Calmettes, Parc Scientifique et Technologique de Luminy, 163 Avenue de Luminy, 13288 Marseille, France
- Correspondence: (J.L.N.); (J.L.I.); Tel.: +34-966-65-8475 (J.L.N.); +33(0)491-82-8803 (J.L.I.)
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Giudici AM, Hernández-Cifre JG, Cámara-Artigas A, Hornos F, Martínez-Rodríguez S, Carlos Alvarez-Pérez J, Díaz-Cano I, Esther Fárez-Vidal M, Neira JL. The isolated armadillo-repeat domain of Plakophilin 1 is a monomer in solution with a low conformational stability. J Struct Biol 2020; 211:107569. [PMID: 32650131 DOI: 10.1016/j.jsb.2020.107569] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Revised: 06/28/2020] [Accepted: 06/30/2020] [Indexed: 12/16/2022]
Abstract
Plakophilin 1 (PKP1) is a member of the armadillo repeat family of proteins. It serves as a scaffold component of desmosomes, which are key structural components for cell-cell adhesion. We have embarked on the biophysical and conformational characterization of the ARM domain of PKP1 (ARM-PKP1) in solution by using several spectroscopic (namely, fluorescence and circular dichroism (CD)) and biophysical techniques (namely, analytical ultracentrifugation (AUC), dynamic light scattering (DLS) and differential scanning calorimetry (DSC)). ARM-PKP1 was a monomer in solution at physiological pH, with a low conformational stability, as concluded from DSC experiments and thermal denaturations followed by fluorescence and CD. The presence or absence of disulphide bridges did not affect its low stability. The protein unfolded through an intermediate which has lost native-like secondary structure. ARM-PKP1 acquired a native-like structure in a narrow pH range (between pH 6.0 and 8.0), indicating that its adherent properties might only work in a very narrow pH range.
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Affiliation(s)
| | - José G Hernández-Cifre
- Departamento de Química Física, Facultad de Química, Campus de Espinardo, Universidad de Murcia, 30100 Murcia, Spain
| | - Ana Cámara-Artigas
- Departamento de Química y Física, Research Center CIAIMBITAL, Universidad de Almería- ceiA3, 04120 Almería, Spain
| | - Felipe Hornos
- IDIBE, Universidad Miguel Hernández, 03202 Elche Alicante, Spain
| | - Sergio Martínez-Rodríguez
- Dpto. Bioquímica y Biología Molecular III e Inmunología, Facultad de Medicina, Universidad de Granada, 18016 Granada, Spain
| | - Juan Carlos Alvarez-Pérez
- Dpto. Bioquímica y Biología Molecular I, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain
| | - Inés Díaz-Cano
- Dpto. Bioquímica y Biología Molecular III e Inmunología, Facultad de Medicina, Universidad de Granada, 18016 Granada, Spain; Instituto de Investigación Biomédica IBS. Granada. Complejo Hospitalario Universitario de Granada, Universidad de Granada, 18071 Granada, Spain
| | - María Esther Fárez-Vidal
- Dpto. Bioquímica y Biología Molecular III e Inmunología, Facultad de Medicina, Universidad de Granada, 18016 Granada, Spain; Instituto de Investigación Biomédica IBS. Granada. Complejo Hospitalario Universitario de Granada, Universidad de Granada, 18071 Granada, Spain.
| | - José L Neira
- IDIBE, Universidad Miguel Hernández, 03202 Elche Alicante, Spain; Instituto de Biocomputación y Física de Sistemas Complejos, Joint Units IQFR-CSIC-BIFI, and GBsC-CSIC-BIFI, Universidad de Zaragoza, 50009 Zaragoza, Spain.
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