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Ranaivoson FM, Bande R, Cardaun I, De Riso A, Gärtner A, Loke P, Reinisch C, Vogirala P, Beaumont E. Crystal structure of human peptidylarginine deiminase type VI (PAD6) provides insights into its inactivity. IUCRJ 2024; 11:395-404. [PMID: 38656308 PMCID: PMC11067741 DOI: 10.1107/s2052252524002549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Accepted: 03/18/2024] [Indexed: 04/26/2024]
Abstract
Human peptidylarginine deiminase isoform VI (PAD6), which is predominantly limited to cytoplasmic lattices in the mammalian oocytes in ovarian tissue, is essential for female fertility. It belongs to the peptidylarginine deiminase (PAD) enzyme family that catalyzes the conversion of arginine residues to citrulline in proteins. In contrast to other members of the family, recombinant PAD6 was previously found to be catalytically inactive. We sought to provide structural insight into the human homologue to shed light on this observation. We report here the first crystal structure of PAD6, determined at 1.7 Å resolution. PAD6 follows the same domain organization as other structurally known PAD isoenzymes. Further structural analysis and size-exclusion chromatography show that PAD6 behaves as a homodimer similar to PAD4. Differential scanning fluorimetry suggests that PAD6 does not coordinate Ca2+ which agrees with acidic residues found to coordinate Ca2+ in other PAD homologs not being conserved in PAD6. The crystal structure of PAD6 shows similarities with the inactive state of apo PAD2, in which the active site conformation is unsuitable for catalytic citrullination. The putative active site of PAD6 adopts a non-productive conformation that would not allow protein-substrate binding due to steric hindrance with rigid secondary structure elements. This observation is further supported by the lack of activity on the histone H3 and cytokeratin 5 substrates. These findings suggest a different mechanism for enzymatic activation compared with other PADs; alternatively, PAD6 may exert a non-enzymatic function in the cytoplasmic lattice of oocytes and early embryos.
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Affiliation(s)
- Fanomezana M. Ranaivoson
- Protein Sciences Department, Evotec (United Kingdom), 95 Park Drive, Abingdon OX14 4RY, United Kingdom
| | - Rieke Bande
- Assay Development Department, Manfred Eigen Campus, Evotec (Germany), Essener Bogen 7, 22419 Hamburg, Germany
| | - Isabell Cardaun
- In vitro Biology Department, Manfred Eigen Campus, Evotec SE, Essener Bogen 7, 22419 Hamburg, Germany
| | - Antonio De Riso
- Protein Sciences Department, Evotec (United Kingdom), 95 Park Drive, Abingdon OX14 4RY, United Kingdom
| | - Annette Gärtner
- In vitro Biology Department, Manfred Eigen Campus, Evotec SE, Essener Bogen 7, 22419 Hamburg, Germany
| | - Pui Loke
- Chemistry Department, Evotec (United Kingdom), 95 Park Drive, Abingdon OX14 4RY, United Kingdom
| | - Christina Reinisch
- Assay Development Department, Manfred Eigen Campus, Evotec (Germany), Essener Bogen 7, 22419 Hamburg, Germany
| | - Prasuna Vogirala
- Protein Sciences Department, Evotec (United Kingdom), 95 Park Drive, Abingdon OX14 4RY, United Kingdom
| | - Edward Beaumont
- Protein Sciences Department, Evotec (United Kingdom), 95 Park Drive, Abingdon OX14 4RY, United Kingdom
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2
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Williams JPC, Walport LJ. PADI6: What we know about the elusive fifth member of the peptidyl arginine deiminase family. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220242. [PMID: 37778376 PMCID: PMC10542454 DOI: 10.1098/rstb.2022.0242] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 03/05/2023] [Indexed: 10/03/2023] Open
Abstract
Peptidyl arginine deiminase 6 (PADI6) is a maternal factor that is vital for early embryonic development. Deletion and mutations of its encoding gene in female mice or women lead to early embryonic developmental arrest, female infertility, maternal imprinting defects and hyperproliferation of the trophoblast. PADI6 is the fifth and least well-characterized member of the peptidyl arginine deiminases (PADIs), which catalyse the post-translational conversion of arginine to citrulline. It is less conserved than the other PADIs, and currently has no reported catalytic activity. While there are many suggested functions of PADI6 in the early mouse embryo, including in embryonic genome activation, cytoplasmic lattice formation, maternal mRNA and ribosome regulation, and organelle distribution, the molecular mechanisms of its function remain unknown. In this review, we discuss what is known about the function of PADI6 and highlight key outstanding questions that must be answered if we are to understand the crucial role it plays in early embryo development and female fertility. This article is part of the Theo Murphy meeting issue 'The virtues and vices of protein citrullination'.
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Affiliation(s)
| | - Louise J. Walport
- Imperial College of Science Technology and Medicine, London, W12 0BZ, UK
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3
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Egbert CM, Warr LR, Pennington KL, Thornton MM, Vaughan AJ, Ashworth SW, Heaton MJ, English N, Torres MP, Andersen JL. The Integration of Proteome-Wide PTM Data with Protein Structural and Sequence Features Identifies Phosphorylations that Mediate 14-3-3 Interactions. J Mol Biol 2023; 435:167890. [PMID: 36402225 PMCID: PMC10099770 DOI: 10.1016/j.jmb.2022.167890] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 10/18/2022] [Accepted: 11/07/2022] [Indexed: 11/18/2022]
Abstract
14-3-3s are abundant proteins that regulate essentially all aspects of cell biology, including cell cycle, motility, metabolism, and cell death. 14-3-3s work by docking to phosphorylated Ser/Thr residues on a large network of client proteins and modulating client protein function in a variety of ways. In recent years, aided by improvements in proteomics, the discovery of 14-3-3 client proteins has far outpaced our ability to understand the biological impact of individual 14-3-3 interactions. The rate-limiting step in this process is often the identification of the individual phospho-serines/threonines that mediate 14-3-3 binding, which are difficult to distinguish from other phospho-sites by sequence alone. Furthermore, trial-and-error molecular approaches to identify these phosphorylations are costly and can take months or years to identify even a single 14-3-3 docking site phosphorylation. To help overcome this challenge, we used machine learning to analyze predictive features of 14-3-3 binding sites. We found that accounting for intrinsic protein disorder and the unbiased mass spectrometry identification rate of a given phosphorylation significantly improves the identification of 14-3-3 docking site phosphorylations across the proteome. We incorporated these features, coupled with consensus sequence prediction, into a publicly available web app, called "14-3-3 site-finder". We demonstrate the strength of this approach through its ability to identify 14-3-3 binding sites that do not conform to the loose consensus sequence of 14-3-3 docking phosphorylations, which we validate with 14-3-3 client proteins, including TNK1, CHEK1, MAPK7, and others. In addition, by using this approach, we identify a phosphorylation on A-kinase anchor protein-13 (AKAP13) at Ser2467 that dominantly controls its interaction with 14-3-3.
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Affiliation(s)
- C M Egbert
- Fritz B. Burns Cancer Research Laboratory, Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, USA
| | - L R Warr
- Department of Statistics, Brigham Young University, Provo, UT, USA
| | - K L Pennington
- Fritz B. Burns Cancer Research Laboratory, Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, USA; Department of Biological and Environmental Sciences, Longwood University, Farmville, VA, USA
| | - M M Thornton
- Department of Computer Science, Brigham Young University, Provo, UT, USA
| | - A J Vaughan
- Fritz B. Burns Cancer Research Laboratory, Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, USA
| | - S W Ashworth
- Fritz B. Burns Cancer Research Laboratory, Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, USA
| | - M J Heaton
- Department of Statistics, Brigham Young University, Provo, UT, USA
| | - N English
- Quantitative Bioscience Program, Georgia Institute of Technology, Atlanta, GA, USA
| | - M P Torres
- Quantitative Bioscience Program, Georgia Institute of Technology, Atlanta, GA, USA; School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - J L Andersen
- Fritz B. Burns Cancer Research Laboratory, Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, USA.
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Abstract
AbstractThe druggable genome is limited by structural features that can be targeted by small molecules in disease-relevant proteins. While orthosteric and allosteric protein modulators have been well studied, they are limited to antagonistic/agonistic functions. This approach to protein modulation leaves many disease-relevant proteins as undruggable targets. Recently, protein-protein interaction modulation has emerged as a promising therapeutic field for previously undruggable protein targets. Molecular glues and heterobifunctional degraders such as PROTACs can facilitate protein interactions and bring the proteasome into proximity to induce targeted protein degradation. In this review, we discuss the function and rational design of molecular glues, heterobifunctional degraders, and hydrophobic tag degraders. We also review historic and novel molecular glues and targets and discuss the challenges and opportunities in this new therapeutic field.
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Virtual Screening and In vitro Evaluation Identify Methotrexate and Testosterone as Inhibitors of Protein Arginine Deiminase 4. Arch Med Res 2022. [DOI: 10.1016/j.arcmed.2022.02.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Horvath M, Petrvalska O, Herman P, Obsilova V, Obsil T. 14-3-3 proteins inactivate DAPK2 by promoting its dimerization and protecting key regulatory phosphosites. Commun Biol 2021; 4:986. [PMID: 34413451 PMCID: PMC8376927 DOI: 10.1038/s42003-021-02518-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 08/03/2021] [Indexed: 01/05/2023] Open
Abstract
Death-associated protein kinase 2 (DAPK2) is a CaM-regulated Ser/Thr protein kinase, involved in apoptosis, autophagy, granulocyte differentiation and motility regulation, whose activity is controlled by autoinhibition, autophosphorylation, dimerization and interaction with scaffolding proteins 14-3-3. However, the structural basis of 14-3-3-mediated DAPK2 regulation remains unclear. Here, we structurally and biochemically characterize the full-length human DAPK2:14-3-3 complex by combining several biophysical techniques. The results from our X-ray crystallographic analysis revealed that Thr369 phosphorylation at the DAPK2 C terminus creates a high-affinity canonical mode III 14-3-3-binding motif, further enhanced by the diterpene glycoside Fusicoccin A. Moreover, concentration-dependent DAPK2 dimerization is disrupted by Ca2+/CaM binding and stabilized by 14-3-3 binding in solution, thereby protecting the DAPK2 inhibitory autophosphorylation site Ser318 against dephosphorylation and preventing Ca2+/CaM binding. Overall, our findings provide mechanistic insights into 14-3-3-mediated DAPK2 inhibition and highlight the potential of the DAPK2:14-3-3 complex as a target for anti‐inflammatory therapies. Horvath et al. structurally and biochemically characterize the full-length human DAPK2-14-3-3 complex to investigate the effects of binding to DAPK2 on its dimerization, activation by dephosphorylation of Ser318, and Ca2+/calmodulin binding. Their results provide mechanistic insights into 14- 3-3-mediated DAPK2 inhibition and highlight the potential of the DAPK2:14-3-3 complex as a target for anti-inflammatory therapies.
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Affiliation(s)
- Matej Horvath
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Prague, Czech Republic.,Department of Structural Biology of Signaling Proteins, Division BIOCEV, Institute of Physiology of the Czech Academy of Sciences, Vestec, Czech Republic
| | - Olivia Petrvalska
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Prague, Czech Republic.,Department of Structural Biology of Signaling Proteins, Division BIOCEV, Institute of Physiology of the Czech Academy of Sciences, Vestec, Czech Republic
| | - Petr Herman
- Institute of Physics, Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic
| | - Veronika Obsilova
- Department of Structural Biology of Signaling Proteins, Division BIOCEV, Institute of Physiology of the Czech Academy of Sciences, Vestec, Czech Republic.
| | - Tomas Obsil
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Prague, Czech Republic. .,Department of Structural Biology of Signaling Proteins, Division BIOCEV, Institute of Physiology of the Czech Academy of Sciences, Vestec, Czech Republic.
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Soini L, Leysen S, Crabbe T, Davis J, Ottmann C. The identification and structural analysis of potential 14-3-3 interaction sites on the bone regulator protein Schnurri-3. Acta Crystallogr F Struct Biol Commun 2021; 77:254-261. [PMID: 34341191 PMCID: PMC8329713 DOI: 10.1107/s2053230x21006658] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 06/25/2021] [Indexed: 11/10/2022] Open
Abstract
14-3-3 proteins regulate many intracellular processes and their ability to bind in subtly different fashions to their numerous partner proteins provides attractive drug-targeting points for a range of diseases. Schnurri-3 is a suppressor of mouse bone formation and a candidate target for novel osteoporosis therapeutics, and thus it is of interest to determine whether it interacts with 14-3-3. In this work, potential 14-3-3 interaction sites on mammalian Schnurri-3 were identified by an in silico analysis of its protein sequence. Using fluorescence polarization, isothermal titration calorimetry and X-ray crystallography, it is shown that synthetic peptides containing either phosphorylated Thr869 or Ser542 can indeed interact with 14-3-3, with the latter capable of forming an interprotein disulfide bond with 14-3-3σ: a hitherto unreported phenomenon.
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Affiliation(s)
- Lorenzo Soini
- Laboratory of Chemical Biology, Department of Biomedical Engineering and Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, The Netherlands
- Department of Chemistry, UCB Celltech, Slough, United Kingdom
| | - Seppe Leysen
- Department of Structural Biology and Biophysics, UCB Celltech, Slough, United Kingdom
| | - Tom Crabbe
- New Targets, UCB Celltech, Slough, United Kingdom
| | - Jeremy Davis
- Department of Chemistry, UCB Celltech, Slough, United Kingdom
| | - Christian Ottmann
- Laboratory of Chemical Biology, Department of Biomedical Engineering and Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, The Netherlands
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Huang B, Zhao Y, Zhou L, Gong T, Feng J, Han P, Qian J. PADI6 Regulates Trophoblast Cell Migration-Invasion Through the Hippo/YAP1 Pathway in Hydatidiform Moles. J Inflamm Res 2021; 14:3489-3500. [PMID: 34326657 PMCID: PMC8314932 DOI: 10.2147/jir.s313422] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 06/29/2021] [Indexed: 12/25/2022] Open
Abstract
Purpose Peptidyl arginine deiminase, type VI (PADI6), a member of the subcortical maternal complex, plays an important role in oocyte growth and the development of fertilized oocytes. Human patients with PADI6 mutations can suffer from multiple reproductive deficiencies including hydatidiform moles and miscarriages. Recent studies have demonstrated that the Hippo signaling pathway plays a central role in the specification of the first cell fates and the maintenance of the human placental trophoblast epithelium. The present study aimed to verify the hypothesis that PADI6 regulates the biological functions of trophoblast cells by targeting YAP1 and to explore the mechanism by which PADI6 accomplishes this in trophoblast cells. Methods Villi from HMs and human trophoblast cell lines were used to identify the localization of PADI6 and YAP1 by immunohistochemistry and immunocytochemistry. PADI6 overexpression and knockdown were induced in human trophoblast cells. Co-immunoprecipitation was used to explore the interaction between PADI6 and YAP1. Wound healing, Transwell and EdU staining assays were used to detect migration, invasion and proliferation. Flow cytometric analysis was used to analyze the cell cycle and apoptosis. β-Tubulin and F-actin levels were determined by Western blot, quantitative real-time PCR and phalloidin staining. Results The results showed that PADI6 and YAP1 had the same expression pattern in villi and colocalized in the cytotrophoblast. An interaction between PADI6 and YAP1 was also confirmed in human trophoblast cell lines. We found that PADI6 positively regulated the expression of YAP1. Functionally, overexpression of PADI6 promoted cell cycle progression and enhanced migration, invasion, proliferation and apoptosis, whereas downregulation of PADI6 showed the opposite effects. Conclusion This study demonstrates that YAP1 is a novel target of PADI6 that serves as an important regulator of trophoblast dysfunction. The crosstalk between the Hippo/YAP1 pathway and the SCMC might be a new topic to explore to uncover the pathological mechanisms of HMs.
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Affiliation(s)
- Bo Huang
- Department of Gynecology and Obstetrics, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou City, 310003, Zhejiang Province, People's Republic of China
| | - Yating Zhao
- Department of Gynecology and Obstetrics, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou City, 310003, Zhejiang Province, People's Republic of China
| | - Lin Zhou
- Department of Gynecology and Obstetrics, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou City, 310003, Zhejiang Province, People's Republic of China
| | - Tingyu Gong
- Department of Gynecology and Obstetrics, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou City, 310003, Zhejiang Province, People's Republic of China
| | - Jiawen Feng
- Department of Gynecology and Obstetrics, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou City, 310003, Zhejiang Province, People's Republic of China
| | - Peilin Han
- Department of Gynecology and Obstetrics, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou City, 310003, Zhejiang Province, People's Republic of China
| | - Jianhua Qian
- Department of Gynecology and Obstetrics, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou City, 310003, Zhejiang Province, People's Republic of China
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Gogl G, Tugaeva KV, Eberling P, Kostmann C, Trave G, Sluchanko NN. Hierarchized phosphotarget binding by the seven human 14-3-3 isoforms. Nat Commun 2021; 12:1677. [PMID: 33723253 PMCID: PMC7961048 DOI: 10.1038/s41467-021-21908-8] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 02/17/2021] [Indexed: 02/07/2023] Open
Abstract
The seven 14-3-3 isoforms are highly abundant human proteins encoded by similar yet distinct genes. 14-3-3 proteins recognize phosphorylated motifs within numerous human and viral proteins. Here, we analyze by X-ray crystallography, fluorescence polarization, mutagenesis and fusicoccin-mediated modulation the structural basis and druggability of 14-3-3 binding to four E6 oncoproteins of tumorigenic human papillomaviruses. 14-3-3 isoforms bind variant and mutated phospho-motifs of E6 and unrelated protein RSK1 with different affinities, albeit following an ordered affinity ranking with conserved relative KD ratios. Remarkably, 14-3-3 isoforms obey the same hierarchy when binding to most of their established targets, as supported by literature and a recent human complexome map. This knowledge allows predicting proportions of 14-3-3 isoforms engaged with phosphoproteins in various tissues. Notwithstanding their individual functions, cellular concentrations of 14-3-3 may be collectively adjusted to buffer the strongest phosphorylation outbursts, explaining their expression variations in different tissues and tumors.
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Affiliation(s)
- Gergo Gogl
- Equipe Labellisee Ligue 2015, Department of Integrated Structural Biology, Institut de Genetique et de Biologie Moleculaire et Cellulaire (IGBMC), INSERM U1258/CNRS UMR 7104/Universite de Strasbourg, Illkirch, France.
| | - Kristina V Tugaeva
- A.N. Bach Institute of Biochemistry, Federal Research Center of Biotechnology of the Russian Academy of Sciences, Moscow, Russia
| | - Pascal Eberling
- Equipe Labellisee Ligue 2015, Department of Integrated Structural Biology, Institut de Genetique et de Biologie Moleculaire et Cellulaire (IGBMC), INSERM U1258/CNRS UMR 7104/Universite de Strasbourg, Illkirch, France
| | - Camille Kostmann
- Equipe Labellisee Ligue 2015, Department of Integrated Structural Biology, Institut de Genetique et de Biologie Moleculaire et Cellulaire (IGBMC), INSERM U1258/CNRS UMR 7104/Universite de Strasbourg, Illkirch, France
| | - Gilles Trave
- Equipe Labellisee Ligue 2015, Department of Integrated Structural Biology, Institut de Genetique et de Biologie Moleculaire et Cellulaire (IGBMC), INSERM U1258/CNRS UMR 7104/Universite de Strasbourg, Illkirch, France.
| | - Nikolai N Sluchanko
- A.N. Bach Institute of Biochemistry, Federal Research Center of Biotechnology of the Russian Academy of Sciences, Moscow, Russia.
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10
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Zhang Y, Yang Y, Hu X, Wang Z, Li L, Chen P. PADs in cancer: Current and future. Biochim Biophys Acta Rev Cancer 2020; 1875:188492. [PMID: 33321174 DOI: 10.1016/j.bbcan.2020.188492] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 12/08/2020] [Accepted: 12/08/2020] [Indexed: 02/06/2023]
Abstract
Protein arginine deiminases (PADs), is a group of calcium-dependent enzymes, which play crucial roles in citrullination, and can catalyze arginine residues into citrulline. This chemical reaction induces citrullinated proteins formation with altered structure and function, leading to numerous pathological diseases, including inflammation and autoimmune diseases. To date, multiple studies have provided solid evidence that PADs are implicated in cancer progression. Nevertheless, the findings on PADs functions in tumors are too complex to understand due to its involvements in variable signaling pathways. The increasing interest in PADs has heightened the need for a comprehensive description for its role in cancer. The present study aims to identify the gaps in present knowledge, including its structures, biological substrates and tissue distribution. Since several irreversible inhibitors for PADs with good potency and selectivity have been explored, the mechanisms on the dysregulation in tumors remain poorly understood. The present study discusses the relationship between PADs and tumor apoptosis, EMT formation and metastasis as well as the implication of neutrophil extracellular traps (NETs) in tumorigenesis. In addition, the potential uses of citrullinated antigens for immunotherapy were proposed.
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Affiliation(s)
- Yu Zhang
- Department of Pathology and Pathophysiology, School of Medicine, Southeast University, Nanjing, Jiangsu 210009, PR China
| | - Yiqiong Yang
- Department of Pathology and Pathophysiology, School of Medicine, Southeast University, Nanjing, Jiangsu 210009, PR China
| | - Xiuxiu Hu
- Department of Pathology and Pathophysiology, School of Medicine, Southeast University, Nanjing, Jiangsu 210009, PR China
| | - Zhi Wang
- Department of Pathology and Pathophysiology, School of Medicine, Southeast University, Nanjing, Jiangsu 210009, PR China
| | - Li Li
- Department of Pathology and Pathophysiology, School of Medicine, Southeast University, Nanjing, Jiangsu 210009, PR China
| | - Pingsheng Chen
- Department of Pathology and Pathophysiology, School of Medicine, Southeast University, Nanjing, Jiangsu 210009, PR China.
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11
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Soini L, Leysen S, Davis J, Ottmann C. A biophysical and structural analysis of the interaction of BLNK with 14-3-3 proteins. J Struct Biol 2020; 212:107662. [PMID: 33176192 DOI: 10.1016/j.jsb.2020.107662] [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: 08/05/2020] [Revised: 11/02/2020] [Accepted: 11/03/2020] [Indexed: 01/14/2023]
Abstract
B-cell linker protein (BLNK) is an adaptor protein that orchestrates signalling downstream of B-cell receptors. It has been reported to undergo proteasomal degradation upon binding to 14-3-3 proteins. Here, we report the first biophysical and structural study of this protein-protein interaction (PPI). Specifically, we investigated the binding of mono- and di- phosphorylated BLNK peptides to 14-3-3 using fluorescent polarization (FP) and isothermal titration calorimetry assays (ITC). Our results suggest that BLNK interacts with 14-3-3 according to the gatekeeper model, where HPK1 mediated phosphorylation of Thr152 (pT152) allows BLNK anchoring to 14-3-3, and an additional phosphorylation of Ser285 (pS285) by AKT, then further improves the affinity. Finally, we have also solved a crystal structure of the BLNKpT152 peptide bound to 14-3-3σ. These findings could serve as important tool for compound discovery programs aiming to modulate this interaction with 14-3-3.
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Affiliation(s)
- Lorenzo Soini
- Laboratory of Chemical Biology, Department of Biomedical Engineering and Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, the Netherlands; Department of Chemistry, UCB Celltech, Slough, UK
| | - Seppe Leysen
- Department of Structural Biology and Biophysics, UCB Celltech, Slough, UK
| | - Jeremy Davis
- Department of Chemistry, UCB Celltech, Slough, UK
| | - Christian Ottmann
- Laboratory of Chemical Biology, Department of Biomedical Engineering and Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, the Netherlands.
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12
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Ballone A, Lau RA, Zweipfenning FPA, Ottmann C. A new soaking procedure for X-ray crystallographic structural determination of protein-peptide complexes. Acta Crystallogr F Struct Biol Commun 2020; 76:501-507. [PMID: 33006579 PMCID: PMC7531243 DOI: 10.1107/s2053230x2001122x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 08/16/2020] [Indexed: 11/29/2022] Open
Abstract
Interactions between a protein and a peptide motif of its protein partner are prevalent in nature. Often, a protein also has multiple interaction partners. X-ray protein crystallography is commonly used to examine these interactions in terms of bond distances and angles as well as to describe hotspots within protein complexes. However, the crystallization process presents a significant bottleneck in structure determination since it often requires notably time-consuming screening procedures, which involve testing a broad range of crystallization conditions via a trial-and-error approach. This difficulty is also increased as each protein-peptide complex does not necessarily crystallize under the same conditions. Here, a new co-crystallization/peptide-soaking method is presented which circumvents the need to return to the initial lengthy crystal screening and optimization processes for each consequent new complex. The 14-3-3σ protein, which has multiple interacting partners with specific peptidic motifs, was used as a case study. It was found that co-crystals of 14-3-3σ and a low-affinity peptide from one of its partners, c-Jun, could easily be soaked with another interacting peptide to quickly and easily generate new structures at high resolution. Not only does this significantly reduce the production time, but new 14-3-3-peptide structures that were previously not accessible with the 14-3-3σ isoform, despite screening hundreds of other different conditions, were now also able to be resolved. The findings achieved in this study may be considered as a supporting and practical guide to potentially enable the acceleration of the crystallization process of any protein-peptide system.
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Affiliation(s)
- Alice Ballone
- Laboratory of Chemical Biology, Department of Biomedical Engineering and Institute for Complex Molecular Systems, Eindhoven University of Technology, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
| | - Roxanne A. Lau
- Laboratory of Chemical Biology, Department of Biomedical Engineering and Institute for Complex Molecular Systems, Eindhoven University of Technology, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
| | - Fabian P. A. Zweipfenning
- Laboratory of Chemical Biology, Department of Biomedical Engineering and Institute for Complex Molecular Systems, Eindhoven University of Technology, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
| | - Christian Ottmann
- Laboratory of Chemical Biology, Department of Biomedical Engineering and Institute for Complex Molecular Systems, Eindhoven University of Technology, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
- Department of Chemistry, University of Duisburg-Essen, Universitätsstrasse 7, 45117 Essen, Germany
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13
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Wolter M, Santo DL, Herman P, Ballone A, Centorrino F, Obsil T, Ottmann C. Interaction of an IκBα Peptide with 14-3-3. ACS OMEGA 2020; 5:5380-5388. [PMID: 32201828 PMCID: PMC7081424 DOI: 10.1021/acsomega.9b04413] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Accepted: 02/19/2020] [Indexed: 06/10/2023]
Abstract
Inflammatory responses mediated by the transcription factor nuclear factor kappa-light-chain enhancer of activated B cells (NF-κB) play key roles in immunity, autoimmune diseases, and cancer. NF-κB is directly regulated through protein-protein interactions, including those with IκB and 14-3-3 proteins. These two important regulatory proteins have been reported to interact with each other, although little is known about this interaction. We analyzed the inhibitor of nuclear factor kappa B α (IκBα)/14-3-3σ interaction via a peptide/protein-based approach. Structural data were acquired via X-ray crystallography, while binding affinities were measured with fluorescence polarization assays and time-resolved tryptophan fluorescence. A high-resolution crystal structure (1.13 Å) of the uncommon 14-3-3 interaction motif of IκBα (IκBαpS63) in a complex with 14-3-3σ was evaluated. This motif harbors a tryptophan that makes this crystal structure the first one with such a residue visible in the electron density at that position. We used this tryptophan to determine the binding affinity of the unlabeled IκBα peptide to 14-3-3 via tryptophan fluorescence decay measurements.
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Affiliation(s)
- Madita Wolter
- Department
of Biomedical Engineering, Laboratory of Chemical Biology and Institute
for Complex Molecular Systems, Eindhoven
University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Domenico Lentini Santo
- Department
of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Prague 12843, Czech Republic
| | - Petr Herman
- Institute
of Physics, Faculty of Mathematics and Physics, Charles University, Prague 12116, Czech Republic
| | - Alice Ballone
- Department
of Biomedical Engineering, Laboratory of Chemical Biology and Institute
for Complex Molecular Systems, Eindhoven
University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Federica Centorrino
- Department
of Biomedical Engineering, Laboratory of Chemical Biology and Institute
for Complex Molecular Systems, Eindhoven
University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Tomas Obsil
- Department
of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Prague 12843, Czech Republic
| | - Christian Ottmann
- Department
of Biomedical Engineering, Laboratory of Chemical Biology and Institute
for Complex Molecular Systems, Eindhoven
University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
- Department
of Organic Chemistry, University of Duisburg-Essen, 45117 Essen, Germany
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14
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Alghamdi M, Al Ghamdi KA, Khan RH, Uversky VN, Redwan EM. An interplay of structure and intrinsic disorder in the functionality of peptidylarginine deiminases, a family of key autoimmunity-related enzymes. Cell Mol Life Sci 2019; 76:4635-4662. [PMID: 31342121 PMCID: PMC11105357 DOI: 10.1007/s00018-019-03237-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Revised: 07/16/2019] [Accepted: 07/18/2019] [Indexed: 12/21/2022]
Abstract
Citrullination is a post-translation modification of proteins, where the proteinaceous arginine residues are converted to non-coded citrulline residues. The immune tolerance to such citrullinated protein can be lost, leading to inflammatory and autoimmune diseases. Citrullination is a chemical reaction mediated by peptidylarginine deiminase enzymes (PADs), which are a family of calcium-dependent cysteine hydrolase enzymes that includes five isotypes: PAD1, PAD2, PAD3, PAD4, and PAD6. Each PAD has specific substrates and tissue distribution, where it modifies the arginine to produce a citrullinated protein with altered structure and function. All mammalian PADs have a sequence similarity of about 70-95%, whereas in humans, they are 50-55% homologous in their structure and amino acid sequences. Being calcium-dependent hydrolases, PADs are inactive under the physiological level of calcium, but could be activated due to distortions in calcium homeostasis, or when the cellular calcium levels are increased. In this article, we analyze some of the currently available data on the structural properties of human PADs, the mechanisms of their calcium-induced activation, and show that these proteins contain functionally important regions of intrinsic disorder. Citrullination represents an important trigger of multiple physiological and pathological processes, and as a result, PADs are recognized to play a number of important roles in autoimmune diseases, cancer, and neurodegeneration. Therefore, we also review the current state of the art in the development of PAD inhibitors with good potency and selectivity.
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Affiliation(s)
- Mohammed Alghamdi
- Biological Sciences Department, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah, 21589, Saudi Arabia
- Laboratory Department, University Medical Services Center, King Abdulaziz University, P.O. Box 80200, Jeddah, 21589, Saudi Arabia
| | - Khaled A Al Ghamdi
- Biological Sciences Department, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah, 21589, Saudi Arabia
| | - Rizwan H Khan
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, UP, India
| | - Vladimir N Uversky
- Biological Sciences Department, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah, 21589, Saudi Arabia.
- Protein Research Group, Institute for Biological Instrumentation of the Russian Academy of Sciences, 7 Institutskaya Str., 142290, Pushchino, Moscow region, Russia.
- Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, USA.
| | - Elrashdy M Redwan
- Biological Sciences Department, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah, 21589, Saudi Arabia.
- Therapeutic and Protective Proteins Laboratory, Protein Research Department, Genetic Engineering and Biotechnology Research Institute, City for Scientific Research and Technology Applications, New Borg EL-Arab, Alexandria, 21934, Egypt.
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15
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Eisa AA, De S, Detwiler A, Gilker E, Ignatious AC, Vijayaraghavan S, Kline D. YWHA (14-3-3) protein isoforms and their interactions with CDC25B phosphatase in mouse oogenesis and oocyte maturation. BMC DEVELOPMENTAL BIOLOGY 2019; 19:20. [PMID: 31640562 PMCID: PMC6805688 DOI: 10.1186/s12861-019-0200-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 09/13/2019] [Indexed: 12/21/2022]
Abstract
Background Immature mammalian oocytes are held arrested at prophase I of meiosis by an inhibitory phosphorylation of cyclin-dependent kinase 1 (CDK1). Release from this meiotic arrest and germinal vesicle breakdown is dependent on dephosphorylation of CDK1 by the protein, cell cycle division 25B (CDC25B). Evidence suggests that phosphorylated CDC25B is bound to YWHA (14-3-3) proteins in the cytoplasm of immature oocytes and is thus maintained in an inactive form. The importance of YWHA in meiosis demands additional studies. Results Messenger RNA for multiple isoforms of the YWHA protein family was detected in mouse oocytes and eggs. All seven mammalian YWHA isoforms previously reported to be expressed in mouse oocytes, were found to interact with CDC25B as evidenced by in situ proximity ligation assays. Interaction of YWHAH with CDC25B was indicated by Förster Resonance Energy Transfer (FRET) microscopy. Intracytoplasmic microinjection of oocytes with R18, a known, synthetic, non-isoform-specific, YWHA-blocking peptide promoted germinal vesicle breakdown. This suggests that inhibiting the interactions between YWHA proteins and their binding partners releases the oocyte from meiotic arrest. Microinjection of isoform-specific, translation-blocking morpholino oligonucleotides to knockdown or downregulate YWHA protein synthesis in oocytes suggested a role for a specific YWHA isoform in maintaining the meiotic arrest. More definitively however, and in contrast to the knockdown experiments, oocyte-specific and global deletion of two isoforms of YWHA, YWHAH (14-3-3 eta) or YWHAE (14-3-3 epsilon) indicated that the complete absence of either or both isoforms does not alter oocyte development and release from the meiotic prophase I arrest. Conclusions Multiple isoforms of the YWHA protein are expressed in mouse oocytes and eggs and interact with the cell cycle protein CDC25B, but YWHAH and YWHAE isoforms are not essential for normal mouse oocyte maturation, fertilization and early embryonic development.
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Affiliation(s)
- Alaa A Eisa
- School of Biomedical Sciences, Kent State University, Kent, OH, 22422, USA
| | - Santanu De
- Department of Biological Sciences, Nova Southeastern University, Fort Lauderdale, FL, 33314, USA
| | - Ariana Detwiler
- Department of Environmental and Occupational Health, University of Pittsburgh Graduate School of Public Health, UPMC Hillman Cancer Center, Pittsburgh, PA, 15213, USA
| | - Eva Gilker
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA
| | | | | | - Douglas Kline
- Department of Biological Sciences, Kent State University, Kent, OH, 44242, USA.
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16
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Martinez-Prat L, Palterer B, Vitiello G, Parronchi P, Robinson WH, Mahler M. Autoantibodies to protein-arginine deiminase (PAD) 4 in rheumatoid arthritis: immunological and clinical significance, and potential for precision medicine. Expert Rev Clin Immunol 2019; 15:1073-1087. [DOI: 10.1080/1744666x.2020.1668778] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Laura Martinez-Prat
- Research and Development, Inova Diagnostics, San Diego, CA, USA
- Department of Experimental Science, Francisco de Vitoria University, Madrid, Spain
| | - Boaz Palterer
- specialist in Allergy and Clinical Immunology, Experimental and Clinical Medicine Department, University of Florence, Florence, Italy
| | - Gianfranco Vitiello
- resident in Allergy and Clinical Immunology, Experimental and Clinical Medicine Department, University of Florence, Florence, Italy
| | - Paola Parronchi
- (Allergy and Clinical Immunology), Laboratory Head, Experimental and Clinical Medicine Department, University of Florence, Florence, Italy
| | - William H. Robinson
- (Immunology and Rheumatology), Division of Immunology and Rheumatology, Stanford University, Stanford, CA, USA
- Geriatric Research Education and Clinical [GRECC] Division, VA Palo Alto Health Care System, Palo Alto, CA, USA
| | - Michael Mahler
- Research and Development, Inova Diagnostics, San Diego, CA, USA
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17
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Shi M, Xu D. Molecular Dynamics Investigations Suggest a Non-specific Recognition Strategy of 14-3-3σ Protein by Tweezer: Implication for the Inhibition Mechanism. Front Chem 2019; 7:237. [PMID: 31058132 PMCID: PMC6478809 DOI: 10.3389/fchem.2019.00237] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Accepted: 03/26/2019] [Indexed: 02/04/2023] Open
Abstract
The supramolecular complex formed between protein and designed molecule has become one of the most efficient ways to modify protein functions. As one of the more well-studied model systems, 14-3-3 family proteins play an important role in regulating intracellular signaling pathways via protein-protein interactions. In this work, we selected 14-3-3σ as the target protein. Molecular dynamics simulations and binding free energy calculations were applied to identify the possible binding sites and understand its recognition ability of the supramolecular inhibitor, the tweezer molecule (CLR01). On the basis of our simulation, major interactions between lysine residues and CLR01 come from the van der Waals interactions between the long alkyl chain of lysine and the cavity formed by the norbornadiene and benzene rings of the inhibitor. Apart from K214, which was found to be crystallized with this inhibitor, other lysine sites have also shown their abilities to form inclusion complexes with the inhibitor. Such non-specific recognition features of CLR01 against 14-3-3σ can be used in the modification of protein functions via supramolecular chemistry.
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Affiliation(s)
- Mingsong Shi
- College of Chemistry, Sichuan University, Chengdu, China
| | - Dingguo Xu
- College of Chemistry, Sichuan University, Chengdu, China
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18
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Smidova A, Alblova M, Kalabova D, Psenakova K, Rosulek M, Herman P, Obsil T, Obsilova V. 14-3-3 protein masks the nuclear localization sequence of caspase-2. FEBS J 2018; 285:4196-4213. [PMID: 30281929 DOI: 10.1111/febs.14670] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 09/28/2018] [Indexed: 12/13/2022]
Abstract
Caspase-2 is an apical protease responsible for the proteolysis of cellular substrates directly involved in mediating apoptotic signaling cascades. Caspase-2 activation is inhibited by phosphorylation followed by binding to the scaffolding protein 14-3-3, which recognizes two phosphoserines located in the linker between the caspase recruitment domain and the p19 domains of the caspase-2 zymogen. However, the structural details of this interaction and the exact role of 14-3-3 in the regulation of caspase-2 activation remain unclear. Moreover, the caspase-2 region with both 14-3-3-binding motifs also contains the nuclear localization sequence (NLS), thus suggesting that 14-3-3 binding may regulate the subcellular localization of caspase-2. Here, we report a structural analysis of the 14-3-3ζ:caspase-2 complex using a combined approach based on small angle X-ray scattering, NMR, chemical cross-linking, and fluorescence spectroscopy. The structural model proposed in this study suggests that phosphorylated caspase-2 and 14-3-3ζ form a compact and rigid complex in which the p19 and the p12 domains of caspase-2 are positioned within the central channel of the 14-3-3 dimer and stabilized through interactions with the C-terminal helices of both 14-3-3ζ protomers. In this conformation, the surface of the p12 domain, which is involved in caspase-2 activation by dimerization, is sterically occluded by the 14-3-3 dimer, thereby likely preventing caspase-2 activation. In addition, 14-3-3 protein binding to caspase-2 masks its NLS. Therefore, our results suggest that 14-3-3 protein binding to caspase-2 may play a key role in regulating caspase-2 activation. DATABASE: The atomic coordinates and structure factors have been deposited in the Protein Data Bank, www.ww pdb.org (PDB ID codes 6GKF and 6GKG).
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Affiliation(s)
- Aneta Smidova
- Department of Structural Biology of Signaling Proteins, Division BIOCEV, Institute of Physiology of the Czech Academy of Sciences, Vestec, Czech Republic
| | - Miroslava Alblova
- Department of Structural Biology of Signaling Proteins, Division BIOCEV, Institute of Physiology of the Czech Academy of Sciences, Vestec, Czech Republic
| | - Dana Kalabova
- Department of Structural Biology of Signaling Proteins, Division BIOCEV, Institute of Physiology of the Czech Academy of Sciences, Vestec, Czech Republic.,2nd Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Katarina Psenakova
- Department of Structural Biology of Signaling Proteins, Division BIOCEV, Institute of Physiology of the Czech Academy of Sciences, Vestec, Czech Republic.,Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Prague, Czech Republic
| | - Michal Rosulek
- Division BIOCEV, Institute of Microbiology of the Czech Academy of Sciences, Vestec, Czech Republic.,Department of Biochemistry, Faculty of Science, Charles University, Prague, Czech Republic
| | - Petr Herman
- Institute of Physics, Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic
| | - Tomas Obsil
- Department of Structural Biology of Signaling Proteins, Division BIOCEV, Institute of Physiology of the Czech Academy of Sciences, Vestec, Czech Republic.,Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Prague, Czech Republic
| | - Veronika Obsilova
- Department of Structural Biology of Signaling Proteins, Division BIOCEV, Institute of Physiology of the Czech Academy of Sciences, Vestec, Czech Republic
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19
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14-3-3 protein directly interacts with the kinase domain of calcium/calmodulin-dependent protein kinase kinase (CaMKK2). Biochim Biophys Acta Gen Subj 2018; 1862:1612-1625. [DOI: 10.1016/j.bbagen.2018.04.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 04/05/2018] [Accepted: 04/06/2018] [Indexed: 01/04/2023]
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20
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Ballone A, Centorrino F, Wolter M, Ottmann C. Structural characterization of 14-3-3ζ in complex with the human Son of sevenless homolog 1 (SOS1). J Struct Biol 2018; 202:210-215. [DOI: 10.1016/j.jsb.2018.01.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Revised: 01/28/2018] [Accepted: 01/30/2018] [Indexed: 12/16/2022]
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21
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Sluchanko NN. Association of Multiple Phosphorylated Proteins with the 14-3-3 Regulatory Hubs: Problems and Perspectives. J Mol Biol 2017; 430:20-26. [PMID: 29180038 DOI: 10.1016/j.jmb.2017.11.010] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 11/21/2017] [Accepted: 11/22/2017] [Indexed: 01/11/2023]
Abstract
14-3-3 proteins are well-known universal regulators binding a vast number of partners by recognizing their phosphorylated motifs, typically located within the intrinsically disordered regions. The abundance of such phosphomotifs ensures the involvement of 14-3-3 proteins in sophisticated protein-protein interaction networks that govern vital cellular processes. Thousands of 14-3-3 partners have been either experimentally identified or predicted, but the spatiotemporal hierarchy of the processes based on 14-3-3 interactions is not clearly understood. This is exacerbated by the lack of available structural information on full regulatory complexes involving 14-3-3, which resist high-resolution structural studies due to the presence of intrinsically disordered regions. Although deducing three-dimensional structures is of particular urgency, structural advances are lagging behind the rate at which novel 14-3-3 partners are discovered. Here I attempted to critically review the current state of the field and in particular to dissect the unknowns, focusing on questions that could help in moving the frontiers forward.
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Affiliation(s)
- Nikolai N Sluchanko
- A.N. Bach Institute of Biochemistry, Federal Research Center "Fundamentals of Biotechnology" of the Russian Academy of Sciences, 119071 Moscow, Russian Federation; Department of Biophysics, School of Biology, Moscow State University, 119991 Moscow, Russian Federation.
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22
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Bier D, Mittal S, Bravo-Rodriguez K, Sowislok A, Guillory X, Briels J, Heid C, Bartel M, Wettig B, Brunsveld L, Sanchez-Garcia E, Schrader T, Ottmann C. The Molecular Tweezer CLR01 Stabilizes a Disordered Protein-Protein Interface. J Am Chem Soc 2017; 139:16256-16263. [PMID: 29039919 PMCID: PMC5691318 DOI: 10.1021/jacs.7b07939] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Indexed: 12/13/2022]
Abstract
Protein regions that are involved in protein-protein interactions (PPIs) very often display a high degree of intrinsic disorder, which is reduced during the recognition process. A prime example is binding of the rigid 14-3-3 adapter proteins to their numerous partner proteins, whose recognition motifs undergo an extensive disorder-to-order transition. In this context, it is highly desirable to control this entropy-costly process using tailored stabilizing agents. This study reveals how the molecular tweezer CLR01 tunes the 14-3-3/Cdc25CpS216 protein-protein interaction. Protein crystallography, biophysical affinity determination and biomolecular simulations unanimously deliver a remarkable finding: a supramolecular "Janus" ligand can bind simultaneously to a flexible peptidic PPI recognition motif and to a well-structured adapter protein. This binding fills a gap in the protein-protein interface, "freezes" one of the conformational states of the intrinsically disordered Cdc25C protein partner and enhances the apparent affinity of the interaction. This is the first structural and functional proof of a supramolecular ligand targeting a PPI interface and stabilizing the binding of an intrinsically disordered recognition motif to a rigid partner protein.
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Affiliation(s)
- David Bier
- Laboratory
of Chemical Biology, Department of Biomedical Engineering and Institute
for Complex Molecular Systems, Eindhoven
University of Technology, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
- Department
of Chemistry, University of Duisburg-Essen, Universitätsstrasse 7, 45117 Essen, Germany
| | - Sumit Mittal
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Kenny Bravo-Rodriguez
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Andrea Sowislok
- Department
of Chemistry, University of Duisburg-Essen, Universitätsstrasse 7, 45117 Essen, Germany
| | - Xavier Guillory
- Laboratory
of Chemical Biology, Department of Biomedical Engineering and Institute
for Complex Molecular Systems, Eindhoven
University of Technology, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
- Department
of Chemistry, University of Duisburg-Essen, Universitätsstrasse 7, 45117 Essen, Germany
| | - Jeroen Briels
- Laboratory
of Chemical Biology, Department of Biomedical Engineering and Institute
for Complex Molecular Systems, Eindhoven
University of Technology, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
- Department
of Chemistry, University of Duisburg-Essen, Universitätsstrasse 7, 45117 Essen, Germany
| | - Christian Heid
- Department
of Chemistry, University of Duisburg-Essen, Universitätsstrasse 7, 45117 Essen, Germany
| | - Maria Bartel
- Laboratory
of Chemical Biology, Department of Biomedical Engineering and Institute
for Complex Molecular Systems, Eindhoven
University of Technology, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
| | - Burkhard Wettig
- Department
of Chemistry, University of Duisburg-Essen, Universitätsstrasse 7, 45117 Essen, Germany
| | - Luc Brunsveld
- Laboratory
of Chemical Biology, Department of Biomedical Engineering and Institute
for Complex Molecular Systems, Eindhoven
University of Technology, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
| | - Elsa Sanchez-Garcia
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Thomas Schrader
- Department
of Chemistry, University of Duisburg-Essen, Universitätsstrasse 7, 45117 Essen, Germany
| | - Christian Ottmann
- Laboratory
of Chemical Biology, Department of Biomedical Engineering and Institute
for Complex Molecular Systems, Eindhoven
University of Technology, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
- Department
of Chemistry, University of Duisburg-Essen, Universitätsstrasse 7, 45117 Essen, Germany
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23
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Sluchanko NN, Tugaeva KV, Greive SJ, Antson AA. Chimeric 14-3-3 proteins for unraveling interactions with intrinsically disordered partners. Sci Rep 2017; 7:12014. [PMID: 28931924 PMCID: PMC5607241 DOI: 10.1038/s41598-017-12214-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 09/05/2017] [Indexed: 01/01/2023] Open
Abstract
In eukaryotes, several “hub” proteins integrate signals from different interacting partners that bind through intrinsically disordered regions. The 14-3-3 protein hub, which plays wide-ranging roles in cellular processes, has been linked to numerous human disorders and is a promising target for therapeutic intervention. Partner proteins usually bind via insertion of a phosphopeptide into an amphipathic groove of 14-3-3. Structural plasticity in the groove generates promiscuity allowing accommodation of hundreds of different partners. So far, accurate structural information has been derived for only a few 14-3-3 complexes with phosphopeptide-containing proteins and a variety of complexes with short synthetic peptides. To further advance structural studies, here we propose a novel approach based on fusing 14-3-3 proteins with the target partner peptide sequences. Such chimeric proteins are easy to design, express, purify and crystallize. Peptide attachment to the C terminus of 14-3-3 via an optimal linker allows its phosphorylation by protein kinase A during bacterial co-expression and subsequent binding at the amphipathic groove. Crystal structures of 14-3-3 chimeras with three different peptides provide detailed structural information on peptide-14-3-3 interactions. This simple but powerful approach, employing chimeric proteins, can reinvigorate studies of 14-3-3/phosphoprotein assemblies, including those with challenging low-affinity partners, and may facilitate the design of novel biosensors.
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Affiliation(s)
- Nikolai N Sluchanko
- A.N. Bach Institute of Biochemistry, Federal Research Center "Fundamentals of Biotechnology" of the Russian Academy of Sciences, 119071, Moscow, Russian Federation. .,Department of biophysics, School of Biology, Moscow State University, 119991, Moscow, Russian Federation.
| | - Kristina V Tugaeva
- A.N. Bach Institute of Biochemistry, Federal Research Center "Fundamentals of Biotechnology" of the Russian Academy of Sciences, 119071, Moscow, Russian Federation.,Department of biochemistry, School of Biology, Moscow State University, 119991, Moscow, Russian Federation
| | - Sandra J Greive
- York Structural Biology Laboratory, Department of Chemistry, University of York, York, YO10 5DD, United Kingdom
| | - Alfred A Antson
- York Structural Biology Laboratory, Department of Chemistry, University of York, York, YO10 5DD, United Kingdom
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24
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Jeong EM, Lee MY, Lee JH, Lee BH, Oh KS. A Dual Readout Assay Based on Fluorescence Polarization and Time-Resolved Fluorescence Resonance Energy Transfer to Screen for RSK1 Inhibitors. Biol Pharm Bull 2017; 39:547-55. [PMID: 27040627 DOI: 10.1248/bpb.b15-00808] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A dual readout assay based on fluorescence polarization (FP) and time-resolved fluorescence resonance energy transfer (TR-FRET) exhibits many advantages over single assay technology in terms of screening quality and efficiency. In this study, we developed a dual readout assay combining FP and TR-FRET to identify ribosomal S6 kinase 1 (RSK1) inhibitors. This dual readout assay can monitor both FP and TR-FRET signals from a single RSK1 kinase reaction by using the immobilized metal affinity for phosphochemical (IMAP)-based assay. The Z' value and signal to background (S/B) ratio were 0.85 and 4.0 using FP, and 0.79 and 10.6 using TR-FRET, which led to performance of a pilot library screening against the drug repositioning set consisting of 2320 compounds with a reasonable reproducibility. From this screening, we identified 16 compounds showing greater than 50% inhibition against RSK1 for both FP and TR-FRET; 6 compounds with greater than 50% inhibition only for FP; and 4 compounds with greater than 50% inhibition only for TR-FRET. In a cell-based functional assay to validate the hit compounds, 10 compounds identified only in a single assay had little effect on the RSK-mediated phosphorylation of liver kinase B1, whereas 5 compounds showing greater than 80% inhibition for both FP and TR-FRET reduced the phosphorylation of liver kinase B1. These results demonstrate that the dual readout assay can be used to identify hit compounds by subsequently monitoring both FP and TR-FRET signals from one RSK1 reaction.
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Affiliation(s)
- Eun-mi Jeong
- Bio-Organic Science Division, Korea Research Institute of Chemical Technology
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25
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Amin B, Voelter W. Human Deiminases: Isoforms, Substrate Specificities, Kinetics, and Detection. PROGRESS IN THE CHEMISTRY OF ORGANIC NATURAL PRODUCTS 2017; 106:203-240. [PMID: 28762090 DOI: 10.1007/978-3-319-59542-9_2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Peptidylarginine deiminase (PAD) enzymes are of enormous interest in biomedicine. They catalyze the conversion of a positively-charged guanidinium at an arginine side chain into a neutral ureido group. As a result of this conversion, proteins acquire the non-ribosomally encoded amino acid "citrulline". This imposes critical influences on the structure and function of the target molecules. In multiple sclerosis, myelin hyper-citrullination promotes demyelination by reducing its compaction and triggers auto-antibody production. Immune responses to citrulline-containing proteins play a central role in the pathogenesis of autoimmune diseases. Moreover, auto-antibodies, specific to citrullinated proteins, such as collagen type I and II and filaggrin, are early detectable in rheumatoid arthritis, serving as diagnostic markers of the disease. Despite their significance, little is understood about the role in demyelinating disorders, diversified cancers, and auto-immune diseases. To impart their biological and pathological effects, it is crucial to better understand the reaction mechanism, kinetic properties, substrate selection, and specificities of peptidylarginine deiminase isoforms.Many aspects of PAD biochemistry and physiology have been ignored in past, but, herein is presented a comprehensive survey to improve our current understandings of the underlying mechanism and regulation of PAD enzymes.
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Affiliation(s)
- Bushra Amin
- Department of Chemistry, University of Pittsburgh, Pittsburgh, 15260, PA, USA.
| | - Wolfgang Voelter
- Interfacultary Institute of Biochemistry, University of Tübingen, Hoppe-Seyler-Str. 4, 72076, Tübingen, BW, Germany
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Saijo S, Nagai A, Kinjo S, Mashimo R, Akimoto M, Kizawa K, Yabe-Wada T, Shimizu N, Takahara H, Unno M. Monomeric Form of Peptidylarginine Deiminase Type I Revealed by X-ray Crystallography and Small-Angle X-ray Scattering. J Mol Biol 2016; 428:3058-73. [DOI: 10.1016/j.jmb.2016.06.018] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 06/20/2016] [Accepted: 06/28/2016] [Indexed: 02/01/2023]
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Petta I, Lievens S, Libert C, Tavernier J, De Bosscher K. Modulation of Protein-Protein Interactions for the Development of Novel Therapeutics. Mol Ther 2016; 24:707-18. [PMID: 26675501 PMCID: PMC4886928 DOI: 10.1038/mt.2015.214] [Citation(s) in RCA: 119] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 11/12/2015] [Indexed: 01/10/2023] Open
Abstract
Protein-protein interactions (PPIs) underlie most biological processes. An increasing interest to investigate the unexplored potential of PPIs in drug discovery is driven by the need to find novel therapeutic targets for a whole range of diseases with a high unmet medical need. To date, PPI inhibition with small molecules is the mechanism that has most often been explored, resulting in significant progress towards drug development. However, also PPI stabilization is gradually gaining ground. In this review, we provide a focused overview of a number of PPIs that control critical regulatory pathways and constitute targets for the design of novel therapeutics. We discuss PPI-modulating small molecules that are already pursued in clinical trials. In addition, we review a number of PPIs that are still under preclinical investigation but for which preliminary data support their use as therapeutic targets.
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Affiliation(s)
- Ioanna Petta
- Receptor Research Laboratories, Cytokine Receptor Lab (CRL), VIB Department of Medical Protein Research, Ghent, Belgium
- Department of Biochemistry, Ghent University, Ghent, Belgium
- Inflammation Research Center, VIB, Ghent, Belgium
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Sam Lievens
- Receptor Research Laboratories, Cytokine Receptor Lab (CRL), VIB Department of Medical Protein Research, Ghent, Belgium
- Department of Biochemistry, Ghent University, Ghent, Belgium
| | - Claude Libert
- Inflammation Research Center, VIB, Ghent, Belgium
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Jan Tavernier
- Receptor Research Laboratories, Cytokine Receptor Lab (CRL), VIB Department of Medical Protein Research, Ghent, Belgium
- Department of Biochemistry, Ghent University, Ghent, Belgium
| | - Karolien De Bosscher
- Receptor Research Laboratories, Cytokine Receptor Lab (CRL), VIB Department of Medical Protein Research, Ghent, Belgium
- Department of Biochemistry, Ghent University, Ghent, Belgium
- Receptor Research Laboratories, Nuclear Receptor Lab (NRL), VIB Department of Medical Protein Research, Ghent, Belgium
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Babula JJ, Liu JY. Integrate Omics Data and Molecular Dynamics Simulations toward Better Understanding of Human 14-3-3 Interactomes and Better Drugs for Cancer Therapy. J Genet Genomics 2015; 42:531-547. [PMID: 26554908 DOI: 10.1016/j.jgg.2015.09.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 09/03/2015] [Accepted: 09/03/2015] [Indexed: 12/13/2022]
Abstract
The 14-3-3 protein family is among the most extensively studied, yet still largely mysterious protein families in mammals to date. As they are well recognized for their roles in apoptosis, cell cycle regulation, and proliferation in healthy cells, aberrant 14-3-3 expression has unsurprisingly emerged as instrumental in the development of many cancers and in prognosis. Interestingly, while the seven known 14-3-3 isoforms in humans have many similar functions across cell types, evidence of isoform-specific functions and localization has been observed in both healthy and diseased cells. The strikingly high similarity among 14-3-3 isoforms has made it difficult to delineate isoform-specific functions and for isoform-specific targeting. Here, we review our knowledge of 14-3-3 interactome(s) generated by high-throughput techniques, bioinformatics, structural genomics and chemical genomics and point out that integrating the information with molecular dynamics (MD) simulations may bring us new opportunity to the design of isoform-specific inhibitors, which can not only be used as powerful research tools for delineating distinct interactomes of individual 14-3-3 isoforms, but also can serve as potential new anti-cancer drugs that selectively target aberrant 14-3-3 isoform.
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Affiliation(s)
- JoAnne J Babula
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, 980 W. Walnut Street, Indianapolis, IN 46202, USA
| | - Jing-Yuan Liu
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, 980 W. Walnut Street, Indianapolis, IN 46202, USA; Department of Computer and Information Science, Indiana University Purdue University Indianapolis, 723 W. Michigan St., Indianapolis, IN 46202, USA.
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Structure and mechanism of a bacterial host-protein citrullinating virulence factor, Porphyromonas gingivalis peptidylarginine deiminase. Sci Rep 2015; 5:11969. [PMID: 26132828 PMCID: PMC4487231 DOI: 10.1038/srep11969] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Accepted: 06/12/2015] [Indexed: 01/08/2023] Open
Abstract
Citrullination is a post-translational modification of higher organisms that deiminates arginines in proteins and peptides. It occurs in physiological processes but also pathologies such as multiple sclerosis, fibrosis, Alzheimer’s disease and rheumatoid arthritis (RA). The reaction is catalyzed by peptidylarginine deiminases (PADs), which are found in vertebrates but not in lower organisms. RA has been epidemiologically associated with periodontal disease, whose main infective agent is Porphyromonas gingivalis. Uniquely among microbes, P. gingivalis secretes a PAD, termed PPAD (Porphyromonas peptidylarginine deiminase), which is genetically unrelated to eukaryotic PADs. Here, we studied function of PPAD and its substrate-free, substrate-complex, and substrate-mimic-complex structures. It comprises a flat cylindrical catalytic domain with five-fold α/β-propeller architecture and a C-terminal immunoglobulin-like domain. The PPAD active site is a funnel located on one of the cylinder bases. It accommodates arginines from peptide substrates after major rearrangement of a “Michaelis loop” that closes the cleft. The guanidinium and carboxylate groups of substrates are tightly bound, which explains activity of PPAD against arginines at C-termini but not within peptides. Catalysis is based on a cysteine-histidine-asparagine triad, which is shared with human PAD1-PAD4 and other guanidino-group modifying enzymes. We provide a working mechanism hypothesis based on 18 structure-derived point mutants.
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Milroy LG, Brunsveld L, Ottmann C. Stabilization and inhibition of protein-protein interactions: the 14-3-3 case study. ACS Chem Biol 2013; 8:27-35. [PMID: 23210482 DOI: 10.1021/cb300599t] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Small-molecule modulation of protein-protein interactions (PPIs) is one of the most exciting but also difficult fields in chemical biology and drug development. As one of the most important "hub" proteins with at least 200-300 interaction partners, the 14-3-3 proteins are an especially fruitful case for PPI intervention. Here, we summarize recent success stories in small-molecule modulation, both inhibition and stabilization, of 14-3-3 PPIs. The chemical breath of modulators includes natural products such as fusicoccin A and derivatives but also compounds identified via high-throughput and in silico screening, which has yielded a toolbox of useful inhibitors and stabilizers for this interesting class of adapter proteins. Protein-protein interactions (PPIs) are involved in almost all biological processes, with any given protein typically engaged in complexes with other proteins for the majority of its lifetime. Hence, proteins function not simply as single, isolated entities but display their roles by interacting with other cellular components. These different interaction patterns are presumably as important as the intrinsic biochemical activity status of the protein itself. The biological role of a protein is therefore decisively dependent on the underlying PPI network that furthermore can show great spatial and temporal variations. A thorough appreciation and understanding of this concept and its regulation mechanisms could help to develop new therapeutic agents and concepts.
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Affiliation(s)
- Lech-Gustav Milroy
- Laboratory of Chemical
Biology,
Department of Biomedical Engineering, Technische Universiteit Eindhoven, Den Dolech, 5612 AZ Eindhoven, The Netherlands
| | - Luc Brunsveld
- Laboratory of Chemical
Biology,
Department of Biomedical Engineering, Technische Universiteit Eindhoven, Den Dolech, 5612 AZ Eindhoven, The Netherlands
| | - Christian Ottmann
- Laboratory of Chemical
Biology,
Department of Biomedical Engineering, Technische Universiteit Eindhoven, Den Dolech, 5612 AZ Eindhoven, The Netherlands
- Chemical Genomics Centre of the Max Planck Society, Otto-Hahn Straße
15, 44227 Dortmund, Germany
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31
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Molzan M, Ottmann C. Synergistic binding of the phosphorylated S233- and S259-binding sites of C-RAF to one 14-3-3ζ dimer. J Mol Biol 2012; 423:486-95. [PMID: 22922483 DOI: 10.1016/j.jmb.2012.08.009] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Revised: 08/12/2012] [Accepted: 08/14/2012] [Indexed: 01/02/2023]
Abstract
C-RAF kinase is a central component of the Ras-RAF-MEK (mitogen-activated protein kinase/extracellular signal-regulated kinase)-ERK (extracellular signal-regulated kinase) pathway, which has been shown to be activated in 30% of human tumors. 14-3-3 proteins inactivate C-RAF by binding to the two N-terminal phosphorylation-dependent binding sites surrounding S233 and S259. 14-3-3 proteins can bind two target sequences located on one polypeptide chain simultaneously, thereby increasing binding affinity compared to single-site binding and possibly allowing regulated 14-3-3 binding through gatekeeper phosphorylation. To date, it was unclear whether 14-3-3 proteins can bind the two N-terminal phosphorylation-dependent binding sites of C-RAF simultaneously. Fluorescence polarization using phosphorylated peptides demonstrated that S233 is the low-affinity and S259 is the high-affinity binding site, while simultaneous engagement of both sites by 14-3-3ζ enhances affinity compared to single-site binding. Determination of a 1:1 stoichiometry for the di-phosphorylated peptide binding to one 14-3-3ζ dimer with isothermal titration calorimetry was supported by the crystal structure of the 14-3-3ζ/C-RAFpS233,pS259 complex. Cellular localization studies validate the significance of these sites for cytoplasmic retention of C-RAF, suggesting an extended mechanism of RAF regulation by 14-3-3 proteins.
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Affiliation(s)
- Manuela Molzan
- Chemical Genomics Centre of the Max-Planck-Society, Otto-Hahn-Strasse 15, 44227 Dortmund, Germany
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