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Araujo-Abad S, Rizzuti B, Soto-Conde L, Vidal M, Abian O, Velazquez-Campoy A, Neira JL, de Juan Romero C. Citrullinating enzyme PADI4 and transcriptional repressor RING1B bind in cancer cells. Int J Biol Macromol 2024; 274:133163. [PMID: 38878927 DOI: 10.1016/j.ijbiomac.2024.133163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Revised: 05/26/2024] [Accepted: 06/12/2024] [Indexed: 06/27/2024]
Abstract
Polycomb groups (PcGs) are transcriptional repressors, formed by a complex of several proteins, involved in multicellular development and cancer epigenetics. One of these proteins is the E3 ubiquitin-protein ligase RING1 (or RING1B), associated with the regulation of transcriptional repression and responsible for monoubiquitylation of the histone H2A. On the other hand, PADI4 is one of the human isoforms of a family of enzymes implicated in the conversion of arginine to citrulline, and it is also involved in the development of glioblastoma, among other types of cancers. In this work, we showed the association of PADI4 and RING1B in the nucleus and cytosol in several cancer cell lines by using immunofluorescence and proximity ligation assays. Furthermore, we demonstrated that binding was hampered in the presence of GSK484, an enzymatic PADI4 inhibitor, suggesting that RING1B could bind to the active site of PADI4, as confirmed by protein-protein docking simulations. In vitro and in silico findings showed that binding to PADI4 occurred for the isolated fragments corresponding to both the N-terminal (residues 1-221) and C-terminal (residues 228-336) regions of RING1B. Binding to PADI4 was also hampered by GSK484, as shown by isothermal titration calorimetry (ITC) experiments for the sole N-terminal region, and by both NMR and ITC for the C-terminal one. The dissociation constants between PADI4 and any of the two isolated RING1B fragments were in the low micromolar range (~2-10 μM), as measured by fluorescence and ITC. The interaction between RING1B and PADI4 might imply citrullination of the former, leading to several biological consequences, as well as being of potential therapeutic relevance for improving cancer treatment with the generation of new antigens.
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Affiliation(s)
- Salome Araujo-Abad
- Cancer Research Group, Faculty of Engineering and Applied Sciences, Universidad de Las Américas, 170124 Quito, Ecuador; IDIBE, Universidad Miguel Hernández, 03202 Elche (Alicante), Spain.
| | - Bruno Rizzuti
- CNR-NANOTEC, SS Rende (CS), Department of Physics, University of Calabria, 87036 Rende, Italy; Institute of Biocomputation and Physics of Complex Systems (BIFI), Universidad de Zaragoza, 50018 Zaragoza, Spain
| | | | - Miguel Vidal
- Centro de Investigaciones Biológicas Margarita Salas (CSIC), Calle Ramiro de Maeztu, 9, 28040 Madrid, Spain
| | - Olga Abian
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Universidad de Zaragoza, 50018 Zaragoza, Spain; Instituto de Investigación Sanitaria de Aragón (IIS Aragón), 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
| | - Adrian Velazquez-Campoy
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Universidad de Zaragoza, 50018 Zaragoza, Spain; Instituto de Investigación Sanitaria de Aragón (IIS Aragón), 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
- IDIBE, Universidad Miguel Hernández, 03202 Elche (Alicante), Spain; Institute of Biocomputation and Physics of Complex Systems (BIFI), Universidad de Zaragoza, 50018 Zaragoza, Spain.
| | - Camino de Juan Romero
- IDIBE, Universidad Miguel Hernández, 03202 Elche (Alicante), Spain; Unidad de Investigación, Fundación para el Fomento de la Investigación Sanitaria y Biomédica de la Comunidad Valenciana (FISABIO), Hospital General Universitario de Elche, Camí de l'Almazara 11, 03203 Elche (Alicante), Spain.
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Schumacher MA, Salinas R, Travis BA, Singh RR, Lent N. M. mazei glutamine synthetase and glutamine synthetase-GlnK1 structures reveal enzyme regulation by oligomer modulation. Nat Commun 2023; 14:7375. [PMID: 37968329 PMCID: PMC10651883 DOI: 10.1038/s41467-023-43243-w] [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: 08/11/2023] [Accepted: 11/03/2023] [Indexed: 11/17/2023] Open
Abstract
Glutamine synthetases (GS) play central roles in cellular nitrogen assimilation. Although GS active-site formation requires the oligomerization of just two GS subunits, all GS form large, multi-oligomeric machines. Here we describe a structural dissection of the archaeal Methanosarcina mazei (Mm) GS and its regulation. We show that Mm GS forms unstable dodecamers. Strikingly, we show this Mm GS oligomerization property is leveraged for a unique mode of regulation whereby labile Mm GS hexamers are stabilized by binding the nitrogen regulatory protein, GlnK1. Our GS-GlnK1 structure shows that GlnK1 functions as molecular glue to affix GS hexamers together, stabilizing formation of GS active-sites. These data, therefore, reveal the structural basis for a unique form of enzyme regulation by oligomer modulation.
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Affiliation(s)
- Maria A Schumacher
- Department of Biochemistry, 307 Research Dr., Box 3711, Duke University Medical Center, Durham, NC, 27710, USA.
| | - Raul Salinas
- Department of Biochemistry, 307 Research Dr., Box 3711, Duke University Medical Center, Durham, NC, 27710, USA
| | - Brady A Travis
- Department of Biochemistry, 307 Research Dr., Box 3711, Duke University Medical Center, Durham, NC, 27710, USA
| | - Rajiv Ranjan Singh
- Department of Biochemistry, 307 Research Dr., Box 3711, Duke University Medical Center, Durham, NC, 27710, USA
| | - Nicholas Lent
- Department of Biochemistry, 307 Research Dr., Box 3711, Duke University Medical Center, Durham, NC, 27710, USA
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Travis BA, Peck JV, Salinas R, Dopkins B, Lent N, Nguyen VD, Borgnia MJ, Brennan RG, Schumacher MA. Molecular dissection of the glutamine synthetase-GlnR nitrogen regulatory circuitry in Gram-positive bacteria. Nat Commun 2022; 13:3793. [PMID: 35778410 PMCID: PMC9249791 DOI: 10.1038/s41467-022-31573-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Accepted: 06/21/2022] [Indexed: 11/23/2022] Open
Abstract
How bacteria sense and respond to nitrogen levels are central questions in microbial physiology. In Gram-positive bacteria, nitrogen homeostasis is controlled by an operon encoding glutamine synthetase (GS), a dodecameric machine that assimilates ammonium into glutamine, and the GlnR repressor. GlnR detects nitrogen excess indirectly by binding glutamine-feedback-inhibited-GS (FBI-GS), which activates its transcription-repression function. The molecular mechanisms behind this regulatory circuitry, however, are unknown. Here we describe biochemical and structural analyses of GS and FBI-GS-GlnR complexes from pathogenic and non-pathogenic Gram-positive bacteria. The structures show FBI-GS binds the GlnR C-terminal domain within its active-site cavity, juxtaposing two GlnR monomers to form a DNA-binding-competent GlnR dimer. The FBI-GS-GlnR interaction stabilizes the inactive GS conformation. Strikingly, this interaction also favors a remarkable dodecamer to tetradecamer transition in some GS, breaking the paradigm that all bacterial GS are dodecamers. These data thus unveil unique structural mechanisms of transcription and enzymatic regulation.
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Affiliation(s)
- Brady A Travis
- Department of Biochemistry, 307 Research Dr., Box 3711, Duke University Medical Center, Durham, NC, 27710, USA
| | - Jared V Peck
- Cryo-EM core, Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, 27514, USA
| | - Raul Salinas
- Department of Biochemistry, 307 Research Dr., Box 3711, Duke University Medical Center, Durham, NC, 27710, USA
| | - Brandon Dopkins
- Department of Biochemistry, 307 Research Dr., Box 3711, Duke University Medical Center, Durham, NC, 27710, USA
| | - Nicholas Lent
- Department of Biochemistry, 307 Research Dr., Box 3711, Duke University Medical Center, Durham, NC, 27710, USA
| | - Viet D Nguyen
- Department of Biochemistry, 307 Research Dr., Box 3711, Duke University Medical Center, Durham, NC, 27710, USA
| | - Mario J Borgnia
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC, USA
| | - Richard G Brennan
- Department of Biochemistry, 307 Research Dr., Box 3711, Duke University Medical Center, Durham, NC, 27710, USA
| | - Maria A Schumacher
- Department of Biochemistry, 307 Research Dr., Box 3711, Duke University Medical Center, Durham, NC, 27710, USA.
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Neira JL, Ortore MG, Florencio FJ, Muro-Pastor MI, Rizzuti B. Dynamics of the intrinsically disordered inhibitor IF7 of glutamine synthetase in isolation and in complex with its partner. Arch Biochem Biophys 2020; 683:108303. [PMID: 32074499 DOI: 10.1016/j.abb.2020.108303] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Revised: 02/09/2020] [Accepted: 02/11/2020] [Indexed: 11/26/2022]
Abstract
Glutamine synthetase (GS) catalyzes the ATP-dependent formation of glutamine from glutamate and ammonia. The activity of Synechocystis sp. PCC 6803 GS is regulated, among other mechanisms, by protein-protein interactions with a 65-residue-long, intrinsically disordered protein (IDP), named IF7. IDPs explore diverse conformations in their free states and, in some cases, in their molecular complexes. We used both nuclear magnetic resonance (NMR) at 11.7 T and small angle X-ray scattering (SAXS) to study the size and the dynamics in the picoseconds-to-nanosecond (ps-ns) timescale of: (i) isolated IF7; and (ii) the IF7/GS complex. Our SAXS findings, together with MD results, show: (i) some of the possible IF7 structures in solution; and, (ii) that the presence of IF7 affected the structure of GS in solution. The joint use of SAXS and NMR shows that movements of each amino acid of IF7 were uncorrelated with those of its neighbors. Residues of IF7 with the largest values of the relaxation rates (R1, R2 and ηxy), in the free and bound species, were mainly clustered around: (i) the C terminus of the protein; and (ii) Ala30. These residues, together with Arg8 (which is a hot-spot residue in the interaction with GS), had a restricted mobility in the presence of GS. The C-terminal region, which appeared more compact in our MD simulations of isolated IF7, seemed to be involved in non-native contacts with GS that help in the binding between the two macromolecules.
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Affiliation(s)
- José L Neira
- IDIBE, Universidad Miguel Hernández, Elche, Alicante, Spain; Instituto de Biocomputación y Física de Sistemas Complejos (BIFI), Joint Units IQFR-CSIC-BIFI, and GBsC-CSIC-BIFI, Universidad de Zaragoza, Zaragoza, Spain.
| | - Maria Grazia Ortore
- Department of Life and Environmental Sciences, Marche Polytechnic University, Ancona, Italy.
| | - Francisco J Florencio
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, Seville, Spain
| | - M Isabel Muro-Pastor
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, Seville, Spain
| | - Bruno Rizzuti
- CNR-NANOTEC, Licryl-UOS Cosenza and CEMIF.Cal, Department of Physics, University of Calabria, Via P. Bucci, Cubo 31 C, 87036, Arcavacata di Rende, Cosenza, Italy
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Neira JL, Florencio FJ, Muro-Pastor MI. The isolated, twenty-three-residue-long, N-terminal region of the glutamine synthetase inactivating factor binds to its target. Biophys Chem 2017; 228:1-9. [DOI: 10.1016/j.bpc.2017.05.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 05/31/2017] [Accepted: 05/31/2017] [Indexed: 01/31/2023]
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Cozza C, Neira JL, Florencio FJ, Muro-Pastor MI, Rizzuti B. Intrinsically disordered inhibitor of glutamine synthetase is a functional protein with random-coil-like pK a values. Protein Sci 2017; 26:1105-1115. [PMID: 28295918 DOI: 10.1002/pro.3157] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Revised: 03/09/2017] [Accepted: 03/10/2017] [Indexed: 01/22/2023]
Abstract
The sequential action of glutamine synthetase (GS) and glutamate synthase (GOGAT) in cyanobacteria allows the incorporation of ammonium into carbon skeletons. In the cyanobacterium Synechocystis sp. PCC 6803, the activity of GS is modulated by the interaction with proteins, which include a 65-residue-long intrinsically disordered protein (IDP), the inactivating factor IF7. This interaction is regulated by the presence of charged residues in both IF7 and GS. To understand how charged amino acids can affect the binding of an IDP with its target and to provide clues on electrostatic interactions in disordered states of proteins, we measured the pKa values of all IF7 acidic groups (Glu32, Glu36, Glu38, Asp40, Asp58, and Ser65, the backbone C-terminus) at 100 mM NaCl concentration, by using NMR spectroscopy. We also obtained solution structures of IF7 through molecular dynamics simulation, validated them on the basis of previous experiments, and used them to obtain theoretical estimates of the pKa values. Titration values for the two Asp and three Glu residues of IF7 were similar to those reported for random-coil models, suggesting the lack of electrostatic interactions around these residues. Furthermore, our results suggest the presence of helical structure at the N-terminus of the protein and of conformational changes at acidic pH values. The overall experimental and in silico findings suggest that local interactions and conformational equilibria do not play a role in determining the electrostatic features of the acidic residues of IF7.
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Affiliation(s)
- Concetta Cozza
- Molecular Biophysics Laboratory, Department of Physics, University of Calabria, Rende, Italy
| | - José L Neira
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Elche, Alicante, Spain.,Instituto de Biocomputación y Física de Sistemas Complejos (BIFI), Unidad Asociada IQFR-CSIC-BIFI, Universidad de Zaragoza, Zaragoza, Spain
| | - Francisco J Florencio
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, Seville, Spain
| | - M Isabel Muro-Pastor
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, Seville, Spain
| | - Bruno Rizzuti
- CNR-NANOTEC, Licryl-UOS Cosenza and CEMIF.Cal, Department of Physics, University of Calabria, Rende, Italy
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Pantoja-Uceda D, Neira JL, Saelices L, Robles-Rengel R, Florencio FJ, Muro-Pastor MI, Santoro J. Dissecting the Binding between Glutamine Synthetase and Its Two Natively Unfolded Protein Inhibitors. Biochemistry 2016; 55:3370-82. [DOI: 10.1021/acs.biochem.6b00072] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - José L. Neira
- Instituto
de Biología Molecular y Celular, Universidad Miguel Hernández, 03202 Elche (Alicante), Spain
- Instituto
de Biocomputación y Física de Sistemas Complejos (BIFI),
Unidad Asociada IQFR-CSIC-BIFI, Universidad de Zaragoza, 50009 Zaragoza, Spain
| | - Lorena Saelices
- Instituto
de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, 41092 Seville, Spain
| | - Rocío Robles-Rengel
- Instituto
de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, 41092 Seville, Spain
| | - Francisco J. Florencio
- Instituto
de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, 41092 Seville, Spain
| | - M. Isabel Muro-Pastor
- Instituto
de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, 41092 Seville, Spain
| | - Jorge Santoro
- Instituto
de Química Física Rocasolano (IQFR), CSIC, 28006 Madrid, Spain
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Saelices L, Robles-Rengel R, Florencio FJ, Muro-Pastor MI. A core of three amino acids at the carboxyl-terminal region of glutamine synthetase defines its regulation in cyanobacteria. Mol Microbiol 2015; 96:483-96. [PMID: 25626767 DOI: 10.1111/mmi.12950] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/24/2015] [Indexed: 11/28/2022]
Abstract
Glutamine synthetase (GS) type I is a key enzyme in nitrogen metabolism, and its activity is finely controlled by cellular carbon/nitrogen balance. In cyanobacteria, a reversible process that involves protein-protein interaction with two proteins, the inactivating factors IF7 and IF17, regulates GS. Previously, we showed that three arginine residues of IFs are critical for binding and inhibition of GS. In this work, taking advantage of the specificity of GS/IFs interaction in the model cyanobacteria Synechocystis sp. PCC 6803 and Anabaena sp. PCC 7120, we have constructed a different chimeric GSs from these two cyanobacteria. Analysis of these proteins, together with a site-directed mutagenesis approach, indicates that a core of three residues (E419, N456 and R459) is essential for the inactivation process. The three residues belong to the last 56 amino acids of the C-terminus of Synechocystis GS. A protein-protein docking modeling of Synechocystis GS in complex with IF7 supports the role of the identified core for GS/IF interaction.
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Affiliation(s)
- Lorena Saelices
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, Seville, 41092, Spain
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