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Roy S, Rangasamy L, Nouar A, Koenig C, Pierroz V, Kaeppeli S, Ferrari S, Patra M, Gasser G. Synthesis and Biological Evaluation of Metallocene-Tethered Peptidyl Inhibitors of CDC25. Organometallics 2021. [DOI: 10.1021/acs.organomet.1c00345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Saonli Roy
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Loganathan Rangasamy
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Assia Nouar
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Christiane Koenig
- Institute of Molecular Cancer Research, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Vanessa Pierroz
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
- Institute of Molecular Cancer Research, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Simon Kaeppeli
- Institute of Molecular Cancer Research, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Stefano Ferrari
- Institute of Molecular Cancer Research, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Malay Patra
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Laboratory of Medicinal Chemistry and Cell Biology, Homi Bhabha Road, Navy Nagar, 400005 Mumbai, India
| | - Gilles Gasser
- Chimie ParisTech, PSL University, CNRS, Institute of Chemistry for Life and Health Sciences, Laboratory for Inorganic Chemical Biology, F-75005 Paris, France
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2
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Walsh R. A reanalysis of protein tyrosine phosphatases inhibitory studies using the unnatural substrate analogue p-nitrophenyl phosphate. Anal Biochem 2019; 572:58-62. [PMID: 30844368 DOI: 10.1016/j.ab.2019.02.025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 02/21/2019] [Accepted: 02/25/2019] [Indexed: 11/17/2022]
Abstract
The determination of inhibition mode is extremely important in the understanding of drug interactions and biological mechanisms. The data presented by Hjortness et al. in their recent papers [1,2] on the inhibition of various Protein Tyrosine Phosphatases addresses this issue in an exemplary manner, determining the mode of inhibition based on global fitting of the data to multiple models of inhibition. However, Protein Tyrosine Phosphatases are known to undergo substrate induced conformational changes, so inhibition models which are based on enzyme that adhere to Michaelis-Menten single substrate kinetics may not be appropriate for examining these interactions. To examine the appropriateness of these models, the reported raw data was examined using a recently developed template for global data fitting in Excel. Based on the sum of squared residuals this analysis demonstrates that the excel template was able to match or improve on the reported fittings and demonstrates that a better fit can be achieved with a model that takes into account p-nitrophenyl phosphate-based substrate activation. Whether the substrate activation observed with this model substrate has physiological relevance is debatable, however, it does correspond to the known conformational rearrangement these enzymes undergo when working on their larger peptide substrates.
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Affiliation(s)
- Ryan Walsh
- Department of Microbiology and Biochemistry, INRS-Institut Armand-Frappier, Laval, Québec, H7V 1B7, Canada.
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3
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Moura M, Conde C. Phosphatases in Mitosis: Roles and Regulation. Biomolecules 2019; 9:E55. [PMID: 30736436 PMCID: PMC6406801 DOI: 10.3390/biom9020055] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 01/31/2019] [Accepted: 02/01/2019] [Indexed: 02/07/2023] Open
Abstract
Mitosis requires extensive rearrangement of cellular architecture and of subcellular structures so that replicated chromosomes can bind correctly to spindle microtubules and segregate towards opposite poles. This process originates two new daughter nuclei with equal genetic content and relies on highly-dynamic and tightly regulated phosphorylation of numerous cell cycle proteins. A burst in protein phosphorylation orchestrated by several conserved kinases occurs as cells go into and progress through mitosis. The opposing dephosphorylation events are catalyzed by a small set of protein phosphatases, whose importance for the accuracy of mitosis is becoming increasingly appreciated. This review will focus on the established and emerging roles of mitotic phosphatases, describe their structural and biochemical properties, and discuss recent advances in understanding the regulation of phosphatase activity and function.
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Affiliation(s)
- Margarida Moura
- IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal.
- i3S-Instituto de Investigação e Inovação em Saúde da Universidade do Porto, 4200-135, Porto, Portugal.
- Programa Doutoral em Biologia Molecular e Celular (MCbiology), Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, 4050-313 Porto, Portugal.
| | - Carlos Conde
- IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal.
- i3S-Instituto de Investigação e Inovação em Saúde da Universidade do Porto, 4200-135, Porto, Portugal.
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4
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Hobiger K, Friedrich T. Voltage sensitive phosphatases: emerging kinship to protein tyrosine phosphatases from structure-function research. Front Pharmacol 2015; 6:20. [PMID: 25713537 PMCID: PMC4322731 DOI: 10.3389/fphar.2015.00020] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 01/21/2015] [Indexed: 02/03/2023] Open
Abstract
The transmembrane protein Ci-VSP from the ascidian Ciona intestinalis was described as first member of a fascinating family of enzymes, the voltage sensitive phosphatases (VSPs). Ci-VSP and its voltage-activated homologs from other species are stimulated by positive membrane potentials and dephosphorylate the head groups of negatively charged phosphoinositide phosphates (PIPs). In doing so, VSPs act as control centers at the cytosolic membrane surface, because they intervene in signaling cascades that are mediated by PIP lipids. The characteristic motif CX5RT/S in the active site classifies VSPs as members of the huge family of cysteine-based protein tyrosine phosphatases (PTPs). Although PTPs have already been well-characterized regarding both, structure and function, their relationship to VSPs has drawn only limited attention so far. Therefore, the intention of this review is to give a short overview about the extensive knowledge about PTPs in relation to the facts known about VSPs. Here, we concentrate on the structural features of the catalytic domain which are similar between both classes of phosphatases and their consequences for the enzymatic function. By discussing results obtained from crystal structures, molecular dynamics simulations, and mutagenesis studies, a possible mechanism for the catalytic cycle of VSPs is presented based on that one proposed for PTPs. In this way, we want to link the knowledge about the catalytic activity of VSPs and PTPs.
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Affiliation(s)
- Kirstin Hobiger
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-Universität Marburg Marburg, Germany
| | - Thomas Friedrich
- Max-Volmer-Laboratory of Biophysical Chemistry, Institute of Chemistry, Technische Universität Berlin Berlin, Germany
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5
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Huang TL, Pian JP, Pan BT. Oncogenic Ras suppresses Cdk1 in a complex manner during the incubation of activated Xenopus egg extracts. Arch Biochem Biophys 2013; 532:61-72. [PMID: 23376039 DOI: 10.1016/j.abb.2013.01.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Revised: 01/12/2013] [Accepted: 01/18/2013] [Indexed: 12/30/2022]
Abstract
The activity of Cdk1 is the driving force for entry into M-phase during the cell cycle. Activation of Cdk1 requires synthesis and accumulation of cyclin B, binding of cyclin B to Cdk1, and removal of the inhibitory tyr-15-Cdk1 phosphorylation. It was previously shown that oncogenic Ras suppresses Cdk1 activation during the incubation of activated Xenopus egg extracts. However, how oncogenic Ras suppresses Cdk1 remained unclear. Using the histone H1 kinase assay to follow Cdk1 activity and Western blot analysis to assess levels of both cyclin B2 and phosphorylated-tyr-15-Cdk1, how oncogenic Ras suppresses Cdk1 is studied. The results indicate that oncogenic Ras suppresses Cdk1 via induction of persistent phosphorylation of tyr-15-Cdk1. Interestingly, the results reveal that, compared with cyclin B2 in control activated egg extracts, which increased, peaked and then declined during the incubation, oncogenic Ras induced continuous accumulation of cyclin B2. The results also indicate that oncogenic Ras induces continuous accumulation of cyclin B2 primarily through stabilization of cyclin B2, which is mediated by constitutive activation of the Raf-Mek-Erk-p90(rsk) pathway. Taken together, these results indicate that oncogenic Ras suppresses Cdk1 in a complex manner: It induces continuous accumulation of cyclin B2, but also causes persistent inhibitory phosphorylation of tyr-15-Cdk1.
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Affiliation(s)
- Tun-Lan Huang
- Graduate Center for Nutritional Sciences, University of Kentucky College of Medicine, Lexington, KY 40536, USA
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6
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Abstract
Phosphoryl transfer plays key roles in signaling, energy transduction, protein synthesis, and maintaining the integrity of the genetic material. On the surface, it would appear to be a simple nucleophile displacement reaction. However, this simplicity is deceptive, as, even in aqueous solution, the low-lying d-orbitals on the phosphorus atom allow for eight distinct mechanistic possibilities, before even introducing the complexities of the enzyme catalyzed reactions. To further complicate matters, while powerful, traditional experimental techniques such as the use of linear free-energy relationships (LFER) or measuring isotope effects cannot make unique distinctions between different potential mechanisms. A quarter of a century has passed since Westheimer wrote his seminal review, 'Why Nature Chose Phosphate' (Science 235 (1987), 1173), and a lot has changed in the field since then. The present review revisits this biologically crucial issue, exploring both relevant enzymatic systems as well as the corresponding chemistry in aqueous solution, and demonstrating that the only way key questions in this field are likely to be resolved is through careful theoretical studies (which of course should be able to reproduce all relevant experimental data). Finally, we demonstrate that the reason that nature really chose phosphate is due to interplay between two counteracting effects: on the one hand, phosphates are negatively charged and the resulting charge-charge repulsion with the attacking nucleophile contributes to the very high barrier for hydrolysis, making phosphate esters among the most inert compounds known. However, biology is not only about reducing the barrier to unfavorable chemical reactions. That is, the same charge-charge repulsion that makes phosphate ester hydrolysis so unfavorable also makes it possible to regulate, by exploiting the electrostatics. This means that phosphate ester hydrolysis can not only be turned on, but also be turned off, by fine tuning the electrostatic environment and the present review demonstrates numerous examples where this is the case. Without this capacity for regulation, it would be impossible to have for instance a signaling or metabolic cascade, where the action of each participant is determined by the fine-tuned activity of the previous piece in the production line. This makes phosphate esters the ideal compounds to facilitate life as we know it.
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Chan YH, Lin CY, Pai SH, Huang JK, Lin CT. An arsenate reductase homologue possessing phosphatase activity from sweet potato (Ipomoea batatas [L.] Lam): kinetic studies and characterization. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2011; 59:3087-3091. [PMID: 21388125 DOI: 10.1021/jf1040542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A cDNA encoding a putative arsenate reductase homologue (IbArsR) was cloned from sweet potato (Ib). The deduced protein showed a high level of sequence homology (16-66%) with ArsRs from other organisms. A 3-D homology structure was created based on AtArsR (PDB code 1T3K ) from Arabidopsis thaliana. The putative active site of protein tyrosine phosphatase (HC(X)(5)R) is conserved in all reported ArsRs. IbArsR was overexpressed and purified. The monomeric nature of the enzyme was confirmed by 15% SDS-PAGE and molecular mass determination of the native enzyme via ESI Q-TOF. The IbArsR lacks arsenate reductase activity but possesses phosphatase activity. The Michaelis constant (K(M)) value for p-nitrophenyl phosphate (pNPP) was 11.11 mM. The phosphatase activity was inhibited by 0.5 mM sodium arsenate [As(V)]. The protein's half-life of deactivation at 25 °C was 6.1 min, and its inactivation rate constant K(d) was 1.1 × 10(-1) min(-1). The enzyme was active in a broad pH range from 4.0 to 11.0 with optimum activity at pH 10.0. Phosphatase would remove phosphate group from nucleic acid or dephosphorylation of other enzymes as regulation signaling.
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Affiliation(s)
- Ya-Hui Chan
- Institute of Bioscience and Biotechnology and Center for Marine Bioenvironment and Biotechnology, National Taiwan Ocean University, Keelung 202, Taiwan
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8
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Romá-Mateo C, Sacristán-Reviriego A, Beresford NJ, Caparrós-Martín JA, Culiáñez-Macià FA, Martín H, Molina M, Tabernero L, Pulido R. Phylogenetic and genetic linkage between novel atypical dual-specificity phosphatases from non-metazoan organisms. Mol Genet Genomics 2011; 285:341-54. [DOI: 10.1007/s00438-011-0611-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Accepted: 02/27/2011] [Indexed: 11/29/2022]
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9
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Lavecchia A, Di Giovanni C, Novellino E. Inhibitors of Cdc25 phosphatases as anticancer agents: a patent review. Expert Opin Ther Pat 2010; 20:405-25. [PMID: 20166845 DOI: 10.1517/13543771003623232] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
IMPORTANCE OF THE FIELD The cell division cycle 25 (Cdc25) family of proteins are highly conserved dual specificity phosphatases that regulate cyclin-dependent kinases, the main gatekeepers of the eukaryotic cell division cycle. The three isoforms of Cdc25, including Cdc25A, Cdc25B and Cdc25C, appear to act on different cyclin-dependent kinase/cyclin complexes at different stages of the cell cycle. Overexpression of Cdc25A and/or Cdc25B, but not Cdc25C, has been detected in numerous cancers and is often correlated with a poor clinical prognosis. Thus, inhibition of these phosphatases may represent a promising therapeutic approach in oncology. AREAS COVERED IN THIS REVIEW The main focus of the present review is to describe the development of Cdc25 inhibitors over the years. We describe different compounds according to the decade of discovery and focus attention on molecules that were published in patents. WHAT THE READER WILL GAIN Insight into the most clinically relevant therapeutic Cdc25 analogues that have been published in over 40 patents over the past 19 years. TAKE HOME MESSAGE Some Cdc25 inhibitors have suppressed in vivo the growth of human tumor xenografts in animals; this confirmed the validity of using Cdc25 phosphatase inhibition as an anticancer strategy, but side effects and toxicity remain to be investigated.
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Affiliation(s)
- Antonio Lavecchia
- Università di Napoli Federico II, Facoltà di Farmacia, Dipartimento di Chimica Farmaceutica e Tossicologica, Drug Discovery Laboratory, Via D. Montesano 49, Napoli, 80131, Italy.
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10
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Bhattacharjee H, Sheng J, Ajees AA, Mukhopadhyay R, Rosen BP. Adventitious arsenate reductase activity of the catalytic domain of the human Cdc25B and Cdc25C phosphatases. Biochemistry 2010; 49:802-9. [PMID: 20025242 DOI: 10.1021/bi9019127] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A number of eukaryotic enzymes that function as arsenate reductases are homologues of the catalytic domain of the human Cdc25 phosphatase. For example, the Leishmania major enzyme LmACR2 is both a phosphatase and an arsenate reductase, and its structure bears similarity to the structure of the catalytic domain of human Cdc25 phosphatase. These reductases contain an active site C-X(5)-R signature motif, where C is the catalytic cysteine, the five X residues form a phosphate binding loop, and R is a highly conserved arginine, which is also present in human Cdc25 phosphatases. We therefore investigated the possibility that the three human Cdc25 isoforms might have adventitious arsenate reductase activity. The sequences for the catalytic domains of Cdc25A, -B, and -C were cloned individually into a prokaryotic expression vector, and their gene products were purified from a bacterial host using nickel affinity chromatography. While each of the three Cdc25 catalytic domains exhibited phosphatase activity, arsenate reductase activity was observed only with Cdc25B and -C. These two enzymes reduced inorganic arsenate but not methylated pentavalent arsenicals. Alteration of either the cysteine and arginine residues of the Cys-X(5)-Arg motif led to the loss of both reductase and phosphatase activities. Our observations suggest that Cdc25B and -C may adventitiously reduce arsenate to the more toxic arsenite and may also provide a framework for identifying other human protein tyrosine phosphatases containing the active site Cys-X(5)-Arg loop that might moonlight as arsenate reductases.
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Affiliation(s)
- Hiranmoy Bhattacharjee
- Department of Cellular Biology and Pharmacology, Florida International University, Herbert Wertheim College of Medicine, Miami, Florida 33199, USA.
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11
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Parks JM, Hu H, Rudolph J, Yang W. Mechanism of Cdc25B phosphatase with the small molecule substrate p-nitrophenyl phosphate from QM/MM-MFEP calculations. J Phys Chem B 2009; 113:5217-24. [PMID: 19301836 DOI: 10.1021/jp805137x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cdc25B is a dual-specificity phosphatase that catalyzes the dephosphorylation of the Cdk2/CycA protein complex. This enzyme is an important regulator of the human cell cycle and has been identified as a potential anticancer target. In general, protein tyrosine phosphatases are thought to bind the dianionic form of the phosphate and employ general acid catalysis via the Asp residue in the highly conserved WPD-loop. However, the Cdc25 phosphatases form a special subfamily based on their distinct differences from other protein tyrosine phosphatases. Although Cdc25B contains the (H/V)CX(5)R catalytic motif present in all other protein tyrosine phosphatases, it lacks an analogous catalytic acid residue. No crystallographic data currently exist for the complex of Cdc25B with Cdk2/CycA, so in addition to its natural protein substrate, experimental and theoretical studies are often carried out with small molecule substrates. In an effort to gain understanding of the dephosphorylation mechanism of Cdc25B with a commonly used small molecule substrate, we have performed simulations of the rate-limiting step of the reaction catalyzed by Cdc25B with the substrate p-nitrophenyl phosphate using the recently developed QM/MM Minimum Free Energy Path method (Hu et al. J. Chem. Phys. 2008, 034105). We have simulated the first step of the reaction with both the monoanionic and the dianionic forms of the substrate, and our calculations favor a mechanism involving the monoanionic form. Thus, Cdc25 may employ a unique dephosphorylation mechanism among protein tyrosine phosphatases, at least in the case of the small molecule substrate p-nitrophenyl phosphate.
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Affiliation(s)
- Jerry M Parks
- Department of Chemistry, Duke University, 124 Science Drive, 5301 French Science Center, Durham, North Carolina 27708-0346, USA
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12
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Winterbourn CC, Hampton MB. Thiol chemistry and specificity in redox signaling. Free Radic Biol Med 2008; 45:549-61. [PMID: 18544350 DOI: 10.1016/j.freeradbiomed.2008.05.004] [Citation(s) in RCA: 889] [Impact Index Per Article: 55.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2008] [Revised: 05/02/2008] [Accepted: 05/06/2008] [Indexed: 12/16/2022]
Abstract
Exposure of cells to sublethal oxidative stress results in the modulation of various signaling pathways. Oxidants can activate and inactivate transcription factors, membrane channels, and metabolic enzymes, and regulate calcium-dependent and phosphorylation signaling pathways. Oxidation and reduction of thiol proteins are thought to be the major mechanisms by which reactive oxidants integrate into cellular signal transduction pathways. This review focuses on mechanisms for sensing and transmitting redox signals, from the perspective of their chemical reactivity with specific oxidants. We discuss substrate preferences for different oxidants and how the kinetics of these reactions determines how each oxidant will react in a cell. This kinetic approach helps to identify initial oxidant-sensitive targets and elucidate mechanisms involved in transmission of redox signals. It indicates that only those proteins with very high reactivity, such as peroxiredoxins, are likely to be direct targets for hydrogen peroxide. Other more modestly reactive thiol proteins such as protein tyrosine phosphatases are more likely to become oxidized by an indirect mechanism. The review also examines oxidative changes observed during receptor-mediated signaling, the strengths and limitations of detection methods for reactive oxidant production, and the evidence for hydrogen peroxide acting as the second messenger. We discuss areas where observations in cell systems can be rationalized with the reactivity of specific oxidants and where further work is needed to understand the mechanisms involved.
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Affiliation(s)
- Christine C Winterbourn
- Free Radical Research Group and the National Research Centre for Growth and Development, Department of Pathology, University of Otago, Christchurch, New Zealand.
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Montes M, Braud E, Miteva MA, Goddard ML, Mondésert O, Kolb S, Brun MP, Ducommun B, Garbay C, Villoutreix BO. Receptor-Based Virtual Ligand Screening for the Identification of Novel CDC25 Phosphatase Inhibitors. J Chem Inf Model 2007; 48:157-65. [DOI: 10.1021/ci700313e] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Matthieu Montes
- UFR biomédicale, Laboratoire de Pharmacochimie Moléculaire et Cellulaire, Université Paris Descartes, Paris, F-75006, France, INSERM U648, Paris, F-75006, France, and CNRS, UMR 5088-IFR 109, University of Toulouse, Route de Narbonne, 31062 Toulouse, France
| | - Emmanuelle Braud
- UFR biomédicale, Laboratoire de Pharmacochimie Moléculaire et Cellulaire, Université Paris Descartes, Paris, F-75006, France, INSERM U648, Paris, F-75006, France, and CNRS, UMR 5088-IFR 109, University of Toulouse, Route de Narbonne, 31062 Toulouse, France
| | - Maria A. Miteva
- UFR biomédicale, Laboratoire de Pharmacochimie Moléculaire et Cellulaire, Université Paris Descartes, Paris, F-75006, France, INSERM U648, Paris, F-75006, France, and CNRS, UMR 5088-IFR 109, University of Toulouse, Route de Narbonne, 31062 Toulouse, France
| | - Mary-Lorène Goddard
- UFR biomédicale, Laboratoire de Pharmacochimie Moléculaire et Cellulaire, Université Paris Descartes, Paris, F-75006, France, INSERM U648, Paris, F-75006, France, and CNRS, UMR 5088-IFR 109, University of Toulouse, Route de Narbonne, 31062 Toulouse, France
| | - Odile Mondésert
- UFR biomédicale, Laboratoire de Pharmacochimie Moléculaire et Cellulaire, Université Paris Descartes, Paris, F-75006, France, INSERM U648, Paris, F-75006, France, and CNRS, UMR 5088-IFR 109, University of Toulouse, Route de Narbonne, 31062 Toulouse, France
| | - Stéphanie Kolb
- UFR biomédicale, Laboratoire de Pharmacochimie Moléculaire et Cellulaire, Université Paris Descartes, Paris, F-75006, France, INSERM U648, Paris, F-75006, France, and CNRS, UMR 5088-IFR 109, University of Toulouse, Route de Narbonne, 31062 Toulouse, France
| | - Marie-Priscille Brun
- UFR biomédicale, Laboratoire de Pharmacochimie Moléculaire et Cellulaire, Université Paris Descartes, Paris, F-75006, France, INSERM U648, Paris, F-75006, France, and CNRS, UMR 5088-IFR 109, University of Toulouse, Route de Narbonne, 31062 Toulouse, France
| | - Bernard Ducommun
- UFR biomédicale, Laboratoire de Pharmacochimie Moléculaire et Cellulaire, Université Paris Descartes, Paris, F-75006, France, INSERM U648, Paris, F-75006, France, and CNRS, UMR 5088-IFR 109, University of Toulouse, Route de Narbonne, 31062 Toulouse, France
| | - Christiane Garbay
- UFR biomédicale, Laboratoire de Pharmacochimie Moléculaire et Cellulaire, Université Paris Descartes, Paris, F-75006, France, INSERM U648, Paris, F-75006, France, and CNRS, UMR 5088-IFR 109, University of Toulouse, Route de Narbonne, 31062 Toulouse, France
| | - Bruno O. Villoutreix
- UFR biomédicale, Laboratoire de Pharmacochimie Moléculaire et Cellulaire, Université Paris Descartes, Paris, F-75006, France, INSERM U648, Paris, F-75006, France, and CNRS, UMR 5088-IFR 109, University of Toulouse, Route de Narbonne, 31062 Toulouse, France
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14
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Variations in intracellular levels of TATA binding protein can affect specific genes by different mechanisms. Mol Cell Biol 2007; 28:83-92. [PMID: 17954564 DOI: 10.1128/mcb.00809-07] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We previously showed that reduced intracellular levels of the TATA binding protein (TBP), brought about by tbp heterozygosity in DT40 cells, resulted in a mitotic delay reflecting reduced expression of the mitotic regulator cdc25B but did not significantly affect overall transcription. Here we extend these findings in several ways. We first provide evidence that the decrease in cdc25B expression reflects reduced activity of the cdc25B core promoter in the heterozygous (TBP-het) cells. Strikingly, mutations in a previously described repressor element that overlaps the TATA box restored promoter activity in TBP-het cells, supporting the idea that the sensitivity of this promoter to TBP levels reflects a competition between TBP and the repressor for DNA binding. To determine whether cells might have mechanisms to compensate for fluctuations in TBP levels, we next examined expression of the two known vertebrate TBP homologues, TLP and TBP2. Significantly, mRNAs encoding both were significantly overexpressed relative to levels observed in wild-type cells. In the case of TLP, this was shown to reflect regulation of the core promoter by both TBP and TLP. Together, our results indicate that variations in TBP levels can affect the transcription of specific promoters in distinct ways, but overall transcription may be buffered by corresponding alterations in the expression of TBP homologues.
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15
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Choi SG, Kim J, Sung ND, Son KH, Cheon HG, Kim KR, Kwon BM. Anthraquinones, Cdc25B phosphatase inhibitors, isolated from the roots of Polygonum multiflorum Thunb. Nat Prod Res 2007; 21:487-93. [PMID: 17497420 DOI: 10.1080/14786410601012265] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Three anthraquinones, Cdc25B phosphatase inhibitors, were isolated from the methanolic extract of the roots of Polygonum multiflorum Thunb. (Polygonaceae). Anthraquinones, physcion (1), emodin (2), and questin (3), inhibited the enzymatic activity of Cdc25B phosphatase with IC(50) values of 62.5, 30, and 34 microg mL(-1), respectively. Emodin (2) and questin (3) strongly inhibited the growth of human colon cancer cells, SW620 with GI(50) values of 6.1 and 0.9 microg mL(-1), respectively. Commercially available anthraquinones, chrysophanol (4), and rhein (5) also inhibited Cdc25B phosphatase with IC(50) values of 10.7 and 22.1 microg mL(-1), respectively.
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Affiliation(s)
- Sung-Gyu Choi
- Korea Research Institute of Bioscience and Biotechnology, University of Science and Technology in Korea, Yoosung-Gu, Daejeon, Republic of Korea
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16
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Varmeh-Ziaie S, Manfredi JJ. The dual specificity phosphatase Cdc25B, but not the closely related Cdc25C, is capable of inhibiting cellular proliferation in a manner dependent upon its catalytic activity. J Biol Chem 2007; 282:24633-41. [PMID: 17591782 DOI: 10.1074/jbc.m703105200] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cdc25B and Cdc25C are closely related dual specificity phosphatases that activate cyclin-dependent kinases by removal of inhibitory phosphorylations, thereby triggering entry into mitosis. Cdc25B, but not Cdc25C, has been implicated as an oncogene and been shown to be overexpressed in a variety of human tumors. Surprisingly, ectopic expression of Cdc25B, but not Cdc25C, inhibits cell proliferation in long term assays. Chimeric proteins generated from the two phosphatases show that the anti-proliferative activity is associated with the C-terminal end of Cdc25B. Indeed, the catalytic domain of Cdc25B is sufficient to suppress cell viability in a manner partially dependent upon its C-terminal 26 amino acids that is shown to influence substrate binding. Mutation analysis demonstrates that both the phosphatase activity of Cdc25B as well as its ability to interact with its substrates contribute to the inhibition of cell proliferation. These results demonstrate key differences in the biological activities of Cdc25B and Cdc25C caused by differential substrate affinity and recognition. This also argues that the antiproliferative activity of Cdc25B needs to be overcome for it to act as an oncogene during tumorigenesis.
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Affiliation(s)
- Shohreh Varmeh-Ziaie
- Department of Oncological Sciences, Mount Sinai School of Medicine, New York, New York 10029, USA
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17
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Tierno MB, Johnston PA, Foster C, Skoko JJ, Shinde SN, Shun TY, Lazo JS. Development and optimization of high-throughput in vitro protein phosphatase screening assays. Nat Protoc 2007; 2:1134-44. [PMID: 17546004 DOI: 10.1038/nprot.2007.155] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We describe here detailed protocols to design, optimize and validate in vitro phosphatase assays that we have utilized to conduct high-throughput screens for inhibitors of dual-specificity phosphatases: CDC25B, mitogen-activated protein kinase phosphatase (MKP)-1 and MKP-3. We provide details of the critical steps that are needed to effectively miniaturize the assay into a 384-well, high-throughput format that is both reproducible and cost effective. In vitro phosphatase assays that are optimized according to these protocols should satisfy the assay performance criteria required for a robust high-throughput assay with Z-factors >0.5, and with low intra-plate, inter-plate and day-to-day variability (CV <20%). Assuming the availability of sufficient active phosphatase enzyme and access to appropriate liquid handling automation and detection instruments, a single investigator should be able to develop a 384-well format high-throughput assay in a period of 3-4 weeks.
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Affiliation(s)
- Marni Brisson Tierno
- Department of Pharmacology, Pittsburgh Molecular Library Screening Center, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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18
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Contour-Galcera MO, Sidhu A, Prévost G, Bigg D, Ducommun B. What's new on CDC25 phosphatase inhibitors. Pharmacol Ther 2007; 115:1-12. [PMID: 17531323 DOI: 10.1016/j.pharmthera.2007.03.009] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2007] [Accepted: 03/26/2007] [Indexed: 11/30/2022]
Abstract
The CDC25 phosphatases are key regulators of cell cycle progression and play a central role in the checkpoint response to DNA damage. Their inhibition may therefore represent a promising therapeutic approach in oncology, and small molecule design strategies are currently leading to the identification of various classes of CDC25 inhibitors. Most structures developed so far are quinonoid-based compounds, but also phosphate surrogates or electrophilic entities. Considering the characteristics of the highly conserved active sites of the enzymes, many mechanisms of action have been proposed for these inhibitors. Quinonoid compounds may oxidize the catalytic site cysteine, but can also be considered as Michaël acceptors capable of reacting with the activated thiolate or other electrophilic entities. Phosphate surrogates are thought to interfere with the arginine residue, leading to reversible enzyme inhibition. But some inhibitors can combine in the same molecule several of these mechanisms, thus by fitting into the active site of the enzyme through one part of the molecule and bringing the reactive moiety in close proximity to the catalytic cysteine. This review summarizes novel classes of inhibitors that show specificity for the CDC25s over other phosphatases, cause cell proliferation inhibition and cell cycle arrest in vitro but also, for several of them, inhibition of xenografted tumoral cell growth in vivo. These promising results confirm the interest of the inhibition of CDC25 phosphatases as an anticancer therapeutic strategy.
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19
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Sohn J, Rudolph J. Temperature dependence of binding and catalysis for the Cdc25B phosphatase. Biophys Chem 2006; 125:549-55. [PMID: 17174465 PMCID: PMC1849978 DOI: 10.1016/j.bpc.2006.11.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2006] [Revised: 11/21/2006] [Accepted: 11/21/2006] [Indexed: 11/28/2022]
Abstract
Using a combination of steady-state and single-turnover kinetics, we probe the temperature dependence of substrate association and chemistry for the reaction of Cdc25B phosphatase with its Cdk2-pTpY/CycA protein substrate. The transition state for substrate association is dominated by an enthalpic barrier (DeltaH(++) of 13 kcal/mol) and has a favorable entropic contribution of 4 kcal/mol at 298 K. Phosphate transfer from Cdk2-pTpY/CycA to enzyme (DeltaH(++) of 12 kcal/mol) is enthalpically more favorable than for the small molecule substrate p-nitrophenyl phosphate (DeltaH(++) of 18 kcal/mol), yet entropically less favorable (TDeltaS(++) of 2 vs. -6 kcal/mol at 298 K, respectively). By measuring the temperature dependence of binding and catalysis for several hotspot mutants involved in binding of protein substrate, we determine the enthalpy-entropy compensations for changes in rates of association and phosphate transfer compared to the wild type system. We conclude that the transition state for enzyme-substrate association involves tight and specific contacts at the remote docking site and that phospho-transfer from Cdk2-pTpY/CycA to the pre-organized active site of the enzyme is accompanied by unfavorable entropic rearrangements that promote rapid product dissociation.
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Affiliation(s)
| | - Johannes Rudolph
- * To whom correspondence should be addressed, phone: (919) 668-6188, fax: (919) 613-8642, e-mail:
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20
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Sohn J, Rudolph J. The energetic network of hotspot residues between Cdc25B phosphatase and its protein substrate. J Mol Biol 2006; 362:1060-71. [PMID: 16950393 PMCID: PMC1769329 DOI: 10.1016/j.jmb.2006.07.090] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2006] [Revised: 07/26/2006] [Accepted: 07/31/2006] [Indexed: 11/28/2022]
Abstract
We have investigated the functional network of hotspot residues at the remote docking site of two cell cycle regulators, namely Cdc25B phosphatase and its native protein substrate Cdk2-pTpY/CycA. Specifically, we have studied the roles of energetically important residues (Arg488, Arg492, Tyr497 on Cdc25B and Asp206 and Asp210 on Cdk2-pTpY/CycA) by generating a diverse set of substitutions and performing double and triple mutant cycle analyses. This transient protein-protein interaction is particularly well-suited for this mutagenic approach because various control experiments ensure that the effect of each mutation is limited to the interaction of interest. We find binary coupling energies for ion pairs and hydrogen bonds ranging from 0.7 kcal/mol to 3.9 kcal/mol and ternary coupling energies of 1.9 kcal/mol and 2.8 kcal/mol. Overall our biochemical analyses are in good agreement with the docked structure of the complex and suggest the following roles for the individual hotspot residues on Cdc25B. The most important contributor, Arg492, forms a specific and tight bidentate interaction with Asp206 and a weaker interaction with Asp210 that cannot be replaced by a Lys. Although Tyr497 does not directly participate in this ionic network, it is important for buttressing Arg492 using both its hydrophobic (aromatic ring) and hydrophilic characteristics (hydrogen bonding). Arg488 participates less specifically in the electrostatic network with Asp206 and Asp210 of the protein substrate as it can partially be replaced by Lys. Our data provide insight how a cluster of residues in a docking site remote from the site of the chemical reaction can bring about efficient and specific substrate recognition.
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Affiliation(s)
- Jungsan Sohn
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
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21
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Tropea JE, Phan J, Waugh DS. Overproduction, purification, and biochemical characterization of the dual specificity H1 protein phosphatase encoded by variola major virus. Protein Expr Purif 2006; 50:31-6. [PMID: 16793284 DOI: 10.1016/j.pep.2006.05.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2006] [Accepted: 05/09/2006] [Indexed: 11/28/2022]
Abstract
Smallpox, a highly contagious infectious disease caused by the variola major virus, has an overall mortality rate of about 30%. Because there currently is no specific treatment for smallpox, and the only prevention is vaccination, there is an urgent need for the development of effective antiviral drugs. The dual specificity protein phosphatase encoded by the smallpox virus (H1) is essential for the production of infectious viral particles, making it a promising molecular target for antiviral therapeutics. Here, we report the molecular cloning, overproduction, purification, and initial biochemical characterization of H1 phosphatase, thereby paving the way for the discovery of small molecule inhibitors.
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Affiliation(s)
- Joseph E Tropea
- Macromolecular Crystallography Laboratory, Center for Cancer Research, National Cancer Institute at Frederick, P.O. Box B, Frederick, MD, USA
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22
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Brisson M, Nguyen T, Wipf P, Joo B, Day BW, Skoko JS, Schreiber EM, Foster C, Bansal P, Lazo JS. Redox regulation of Cdc25B by cell-active quinolinediones. Mol Pharmacol 2005; 68:1810-20. [PMID: 16155209 DOI: 10.1124/mol.105.016360] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Intracellular reduction and oxidation pathways regulate protein functionality through both reversible and irreversible mechanisms. The Cdc25 phosphatases, which control cell cycle progression, are potential subjects of oxidative regulation. Many of the more potent Cdc25 phosphatase inhibitors reported to date are quinones, which are capable of redox cycling. Therefore, we used the previously characterized quinolinedione Cdc25 inhibitor DA3003-1 [NSC 663284 or 6-chloro-7-(2-morpholin-4-yl-ethylamino)-quinoline-5,8-dione] and a newly synthesized congener JUN1111 [7-(2-morpholin-4-yl-ethylamino)-quinoline-5,8-dione] to test the hypothesis that quinone inhibitors of Cdc25 regulate phosphatase activity through redox mechanisms. Like DA3003-1, JUN1111 selectively inhibited Cdc25 phosphatases in vitro in an irreversible, time-dependent manner and arrested cells in the G1 and G2/M phases of the cell cycle. It is noteworthy that both DA3003-1 and JUN1111 directly inhibited Cdc25B activity in cells. Depletion of glutathione increased cellular sensitivity to DA3003-1 and JUN1111, and in vitro Cdc25B inhibition by these compounds was sensitive to pH, catalase, and reductants (dithiothreitol and glutathione), consistent with oxidative inactivation. In addition, both DA3003-1 and JUN1111 rapidly generated intracellular reactive oxygen species. Analysis of Cdc25B by mass spectrometry revealed sulfonic acid formation on the catalytic cysteine of Cdc25B after in vitro treatment with DA3003-1. These results indicate that irreversible oxidation of the catalytic cysteine of Cdc25B is indeed a mechanism by which these quinolinediones inactivate this protein phosphatase.
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Affiliation(s)
- Marni Brisson
- Department of Pharmacology, University of Pittsburgh, Biomedical Science Tower 3-Suite 1032, 3501 Fifth Ave, Pittsburgh, Pennsylvania 15260, USA
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23
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Abstract
The Cdc25 phosphatases are essential for cell-cycle control in eukaryotes under normal conditions and in response to DNA damage via checkpoint controls. Recent evidence indicates direct control of the Cdc25s, and therefore the cell cycle, in response to changes in cellular redox status. These redox changes may originate intracellularly from mitochondrial leakage or in response to specific external triggers leading to production of reactive oxygen species (ROS). This review shows that the known chemistry and biology of the Cdc25s favor a direct role for these phosphatases in temporarily blocking cell-cycle progression until favorable reducing conditions are restored. First, the Cdc25s contain a highly reactive cysteine at the active site that can react directly with ROS, leading to enzyme inactivation. Second, the ROS-inactivated form of Cdc25 is expected to prevent cell-cycle progression based on precedent from cellular responses to DNA damage. Third, ROS-mediated oxidation of the Cdc25s leads to an intramolecular disulfide that is readily reversible by the cellular reductant thioredoxin. Finally, in vivo data supporting a direct role for the Cdc25s in redox regulation are considered.
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Affiliation(s)
- Johannes Rudolph
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA.
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24
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Peyregne VP, Kar S, Ham SW, Wang M, Wang Z, Carr BI. Novel hydroxyl naphthoquinones with potent Cdc25 antagonizing and growth inhibitory properties. Mol Cancer Ther 2005; 4:595-602. [PMID: 15827333 DOI: 10.1158/1535-7163.mct-04-0274] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Cdc25 phosphatases are important in cell cycle control and activate cyclin-dependent kinases (Cdk). Efforts are currently under way to synthesize specific small-molecule Cdc25 inhibitors that might have anticancer properties. NSC 95397, a protein tyrosine phosphatase antagonist from the National Cancer Institute library, was reported to be a potent Cdc25 inhibitor. We have synthesized two hydroxyl derivatives of NSC 95397, monohydroxyl-NSC 95397 and dihydroxyl-NSC 95397, which both have enhanced activity for inhibiting Cdc25s. The new analogues, especially dihydroxyl-NSC 95397, potently inhibited the growth of human hepatoma and breast cancer cells in vitro. They influenced two signaling pathways. The dual phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) was induced, likely due to inhibition of the ERK phosphatase activity in Hep 3B cell lysate but not the dual specificity ERK phosphatase MKP-1. They also inhibited Cdc25 enzymatic activities and induced tyrosine phosphorylation of the Cdc25 target Cdks. Addition of hydroxyl groups to the naphthoquinone ring thus enhanced the potency of NSC 95397. These two new compounds may be useful probes for the biological functions of Cdc25s and have the potential for disrupting the cell cycle of growing tumor cells.
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Affiliation(s)
- Vincent P Peyregne
- Liver Cancer Center, Starzl Transplantation Institute, Department of Surgery, University of Pittsburgh School of Medicine, E1552 Biomedical Science Tower, 200 Lothrop Street, Pittsburgh, PA 15213
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25
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Rudolph J. Reactivity of Cdc25 phosphatase at low pH and with thiophosphorylated protein substrate. Bioorg Chem 2005; 33:264-73. [PMID: 16023486 DOI: 10.1016/j.bioorg.2005.01.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2004] [Revised: 01/21/2005] [Accepted: 01/21/2005] [Indexed: 11/16/2022]
Abstract
Cdc25s, dual-specificity phosphatases that dephosphorylate and activate cyclin-dependent kinases, are important regulators of the eukaryotic cell cycle. Herein, we probe the protonation state of the phosphate on the protein substrate of Cdc25 by pH-dependent studies and thiosubstitution. We have extended the useable range of pH for this enzyme substrate pair by using high concentrations of glycerol under acidic conditions. Using the protein substrate, we find a slope of 2 for the acidic side of the bell-shaped pH-rate profile, as found with other protein tyrosine phosphatases. Using thiophosphorylated protein substrate, we find no change in the basic side of the pH-rate profile, despite a large reduction in activity as measured by kcat/Km (0.18%) or kcat (0. 11%). In contrast, the acidic side of the profile changes shows a slope of 1, consistent with the 1.5 pH unit shift associated with thiosubstitution. Thus, Cdc25, like other protein phosphatases, uses a dianionic phosphorylated substrate.
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Affiliation(s)
- Johannes Rudolph
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA.
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26
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Sohn J, Kristjánsdóttir K, Safi A, Parker B, Kiburz B, Rudolph J. Remote hot spots mediate protein substrate recognition for the Cdc25 phosphatase. Proc Natl Acad Sci U S A 2004; 101:16437-41. [PMID: 15534213 PMCID: PMC534539 DOI: 10.1073/pnas.0407663101] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cdc25B is a phosphatase that catalyzes the dephosphorylation and activation of the cyclin-dependent kinases, thus driving cell cycle progression. We have identified two residues, R488 and Y497, located >20 A from the active site, that mediate protein substrate recognition without affecting activity toward small-molecule substrates. Injection of Cdc25B wild-type but not the R488L or Y497A variants induces germinal vesicle breakdown and cyclin-dependent kinase activation in Xenopus oocytes. The conditional knockout of the cdc25 homolog (mih1) in Saccharomyces cerevisiae can be complemented by the wild type but not by the hot spot variants, indicating that protein substrate recognition by the Cdc25 phosphatases is an essential and evolutionarily conserved feature.
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Affiliation(s)
- J Sohn
- Departments of Biochemistry and Chemistry, Duke University Medical Center, Durham, NC 27710, USA
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27
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Abstract
The Cdc25 phosphatases function as key regulators of the cell cycle during normal eukaryotic cell division and as mediators of the checkpoint response in cells with DNA damage. The role of Cdc25s in cancer has become increasingly evident in recent years. More than 20 studies of patient samples from diverse cancers show significant overexpression of Cdc25 with frequent correlation to clinical outcome. Recent screening and design efforts have yielded novel classes of inhibitors that show specificity for the Cdc25s over other phosphatases and cause cell cycle arrest in vivo. Herein we provide a single source for those interested in the cellular functions of Cdc25 in cell cycle progression, its role in the progress of cancer and survival of cancer patients, and recent efforts in the design of specific inhibitors.
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Affiliation(s)
- K Kristjánsdóttir
- Departments of Biochemistry and Chemistry, Duke University Medical Center, LSRC Building, Room C125, Durham, North Carolina 27710, USA
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28
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Brisson M, Nguyen T, Vogt A, Yalowich J, Giorgianni A, Tobi D, Bahar I, Stephenson CRJ, Wipf P, Lazo JS. Discovery and Characterization of Novel Small Molecule Inhibitors of Human Cdc25B Dual Specificity Phosphatase. Mol Pharmacol 2004; 66:824-33. [PMID: 15231869 DOI: 10.1124/mol.104.001784] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cdc25A and Cdc25B dual-specificity phosphatases are key regulators of cell cycle transition and proliferation. They have oncogenic properties and are overexpressed in many human tumors. Because selective Cdc25 phosphatase inhibitors would be valuable biological tools and possible therapeutic agents, we have assayed a small molecule library for in vitro inhibition of Cdc25. We now report the identification of two new structurally distinct classes of Cdc25 inhibitors with cellular activity. The cyclopentaquinoline 3a,4,5,9b-tetrahydro-3H-cyclopenta[c]quinoline-4,8-dicarboxylic acid (5661118) and the naphthofurandione 3-benzoyl-naphtho[1,2-b]furan-4,5-dione (5169131) had in vitro IC50 values of 2.5 to 11 microM against recombinant Cdc25 and were less potent inhibitors of other phosphatases. Unlike 5661118, 5169131 caused reversible inhibition of Cdc25B and displayed competitive inhibitor kinetics. No growth inhibitory activity was seen with 5661118, whereas 10 to 30 microM 5169131 caused G1/S and G2/M arrest. We also found that 5169131 inhibited human PC-3 prostate and MDA-MB-435 breast cancer cell proliferation. Concentration-dependent Tyr15 hyperphosphorylation was seen on cyclin-dependent kinase with a 1-h 5169131 treatment, consistent with Cdc25 inhibition. Cells resistant to DNA toposiomerase II inhibitors were as sensitive to 5169131 as parental cells, indicating that this quinone compound does not inhibit topoisomerase II in vivo. Molecular modeling was used to predict a potential interaction site between the inhibitor and Cdc25B and to provide insights as to the molecular origins of the experimental observations. Based on its kinetic profile and cellular activity, we suggest that 5169131 could be an excellent tool for further studies on the cellular roles of Cdc25.
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Affiliation(s)
- Marni Brisson
- Department of Pharmacology, University of Pittsburgh, PA 15261-0001, USA
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29
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Stone JR. An assessment of proposed mechanisms for sensing hydrogen peroxide in mammalian systems. Arch Biochem Biophys 2004; 422:119-24. [PMID: 14759598 DOI: 10.1016/j.abb.2003.12.029] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2003] [Revised: 12/22/2003] [Indexed: 10/26/2022]
Abstract
Despite much recent interest in the biochemistry of reactive oxygen species, the mechanisms by which hydrogen peroxide (H2O2) functions in mammalian cells remain poorly defined. Proposed mechanisms for sensing H2O2 in mammalian cells include inactivation of protein tyrosine phosphatases and dual specificity phosphatases as well as inactivation of peroxiredoxins. In this critical review, proteins proposed to serve as sensors for H2O2 in mammals will be compared to peroxidases, catalases, and the bacterial H2O2 sensor OxyR for their ability to react with H2O2, in the context of our current knowledge concerning the concentrations of H2O2 present in cells.
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Affiliation(s)
- James R Stone
- Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.
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30
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Zhang ZY. Mechanistic studies on protein tyrosine phosphatases. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 2004; 73:171-220. [PMID: 12882518 DOI: 10.1016/s0079-6603(03)01006-7] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The human genome encodes approximately 100 phosphatases that belong to the protein tyrosine phosphatase (PTP) superfamily. The hallmark for this superfamily is the active site sequence C(X)5R, also known as the PTP signature motif. The PTPs are key regulatory components in signal transduction pathways and the importance of PTPs in the control of cellular signaling is well established. Based on structure and substrate specificity, the PTP superfamily is divided into four distinct subfamilies: (1) pTyr-specific PTPs, (2) dual specificity phosphatases, (3) Cdc25 phosphatases, and (4) LMW PTPs. The PTPs have similar core structures made of a central parallel beta-sheet with flanking a-helices containing a beta-loop-alpha-loop that encompasses the PTP signature motif. Site-directed mutagenesis of conserved amino acids in the Yersinia PTP and several other phosphatases in the PTP superfamily combined with detailed kinetic and mechanistic analyses have revealed a common chemical mechanism for phosphate hydrolysis despite the differences in substrate specificity. This article reviews our current knowledge of the common features important for PTP catalysis, the nature of the enzymatic transition state, and the roles of essential residues in transition stabilization. Future mechanistic studies of PTPs will focus on the use of physiological substrates to determine the molecular basis of substrate recognition and regulation, which is essential for understanding the specific functional role of PTPs in cellular signaling.
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Affiliation(s)
- Zhong-Yin Zhang
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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31
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Abstract
In higher eukaryotes, the S phase and M phase of the cell cycle are triggered by different cyclin-dependent kinases (CDKs). For example, in frog egg extracts, Cdk1-cyclin B catalyzes entry into mitosis but cannot trigger DNA replication. Two hypotheses can explain this observation: Either Cdk1-cyclin B fails to recognize the key substrates of its S-phase-promoting counterparts, or its activity is somehow regulated to prevent it from activating DNA synthesis. Here, we show that Cdk1-cyclin B1 has cryptic S-phase-promoting abilities that can be unmasked by relocating it from the cytoplasm to the nucleus and moderately stimulating its activity. Subcellular localization of vertebrate CDKs and the control of their activity are thus critical factors for determining their specificity.
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Affiliation(s)
- Jonathan D Moore
- Cancer Research UK London Research Institute, Clare Hall Laboratories, Blanche Lane, South Mimms, Herts EN6 3LD, UK
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32
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Lyon MA, Ducruet AP, Wipf P, Lazo JS. Dual-specificity phosphatases as targets for antineoplastic agents. Nat Rev Drug Discov 2002; 1:961-76. [PMID: 12461518 DOI: 10.1038/nrd963] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Dual-specificity protein phosphatases are a subclass of protein tyrosine phosphatases that are uniquely able to hydrolyse the phosphate ester bond on both a tyrosine and a threonine or serine residue on the same protein. Dual-specificity phosphatases have a central role in the complex regulation of signalling pathways that are involved in cell stress responses, proliferation and death. Although this enzyme family is increasingly the target of drug discovery efforts in pharmaceutical companies, a summary of the salient developments in the biology and medicinal chemistry of dual-specificity phosphatases has been lacking. We hope that this comprehensive overview will stimulate further progress in the development of small-molecule inhibitors that could form the basis for a new class of target-directed therapeutic agents.
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Affiliation(s)
- Michael A Lyon
- Department of Chemistry, Chevron Science Center, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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33
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Wipf P, Hopkins CR, Phillips EO, Lazo JS. Separation of Cdc25 dual specificity phosphatase inhibition and DNA cleaving activities in a focused library of analogs of the antitumor antibiotic Dnacin. Tetrahedron 2002. [DOI: 10.1016/s0040-4020(02)00636-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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34
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Lazo JS, Nemoto K, Pestell KE, Cooley K, Southwick EC, Mitchell DA, Furey W, Gussio R, Zaharevitz DW, Joo B, Wipf P. Identification of a potent and selective pharmacophore for Cdc25 dual specificity phosphatase inhibitors. Mol Pharmacol 2002; 61:720-8. [PMID: 11901209 DOI: 10.1124/mol.61.4.720] [Citation(s) in RCA: 148] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Small molecules provide powerful tools to interrogate biological pathways but many important pathway participants remain refractory to inhibitors. For example, Cdc25 dual-specificity phosphatases regulate mammalian cell cycle progression and are implicated in oncogenesis, but potent and selective inhibitors are lacking for this enzyme class. Thus, we evaluated 10,070 compounds in a publicly available chemical repository of the National Cancer Institute for in vitro inhibitory activity against oncogenic, full-length, recombinant human Cdc25B. Twenty-one compounds had mean inhibitory concentrations of <1 microM; >75% were quinones and >40% were of the para-naphthoquinone structural type. Most notable was NSC 95397 (2,3-bis-[2-hydroxyethylsulfanyl]-[1,4]naphthoquinone), which displayed mixed inhibition kinetics with in vitro K(i) values for Cdc25A, -B, and -C of 32, 96, and 40 nM, respectively. NSC 95397 was more potent than any inhibitor of dual specificity phosphatases described previously and 125- to 180-fold more selective for Cdc25A than VH1-related dual-specificity phosphatase or protein tyrosine phosphatase 1b, respectively. Modification of the bis-thioethanol moiety markedly decreased enzyme inhibitory activity, indicating its importance for bioactivity. NSC 95397 showed significant growth inhibition against human and murine carcinoma cells and blocked G(2)/M phase transition. A potential Cdc25 site of interaction was postulated based on molecular modeling with these quinones. We propose that inhibitors based on this chemical structure could serve as useful tools to probe the biological function of Cdc25.
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Affiliation(s)
- John S Lazo
- Department of Pharmacology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA.
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35
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McCain DF, Catrina IE, Hengge AC, Zhang ZY. The catalytic mechanism of Cdc25A phosphatase. J Biol Chem 2002; 277:11190-200. [PMID: 11805096 DOI: 10.1074/jbc.m109636200] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cdc25 phosphatases are dual specificity phosphatases that dephosphorylate and activate cyclin-dependent kinases (CDKs), thereby effecting the progression from one phase of the cell cycle to the next. Despite its central role in the cell cycle, relatively little is known about the catalytic mechanism of Cdc25. In order to provide insights into the catalytic mechanism of Cdc25, we have performed a detailed mechanistic analysis of the catalytic domain of human Cdc25A. Our kinetic isotope effect results, Bronsted analysis, and pH dependence studies employing a range of aryl phosphates clearly indicate a dissociative transition state for the Cdc25A reaction that does not involve a general acid for the hydrolysis of substrates with low leaving group pK(a) values (5.45-8.05). Interestingly, our Bronsted analysis and pH dependence studies reveal that Cdc25A employs a different mechanism for the hydrolysis of substrates with high leaving group pK(a) values (8.68-9.99) that appears to require the protonation of glutamic acid 431. Mutation of glutamic acid 431 into glutamine leads to a dramatic drop in the hydrolysis rate for the high leaving group pK(a) substrates and the disappearance of the basic limb of the pH rate profile for the substrate with a leaving group pK(a) of 8.05, indicating that glutamic acid 431 is essential for the efficient hydrolysis of substrates with high leaving group pK(a). We suggest that hydrolysis of the high leaving group pK(a) substrates proceeds through an unfavored but more catalytically active form of Cdc25A, and we propose several models illustrating this. Since the activity of Cdc25A toward small molecule substrates is several orders of magnitude lower than toward the physiological substrate, cyclin-CDK, we suggest that the cyclin-CDK is able to preferentially induce this more catalytically active form of Cdc25A for efficient phosphothreonine and phosphotyrosine dephosphorylation.
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Affiliation(s)
- Daniel F McCain
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York, 10461, USA
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36
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Freire MM, Mignaco JA, de Carvalho-Alves PC, Barrabin H, Scofano HM. 3-O-methylfluorescein phosphate as a fluorescent substrate for plasma membrane Ca2+-ATPase. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1553:238-48. [PMID: 11997133 DOI: 10.1016/s0005-2728(01)00245-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
3-O-methylfluorescein phosphate hydrolysis, catalyzed by purified erythrocyte Ca2+-ATPase in the absence of Ca2+, was slow in the basal state, activated by phosphatidylserine and controlled proteolysis, but not by calmodulin. p-Nitrophenyl phosphate competitively inhibits hydrolysis in the absence of Ca2+, while ATP inhibits it with a complex kinetics showing a high and a low affinity site for ATP. Labeling with fluorescein isothiocyanate impairs the high affinity binding of ATP, but does not appreciably modify the binding of any of the pseudosubstrates. In the presence of calmodulin, an increase in the Ca2+ concentration produces a bell-shaped curve with a maximum at 50 microM Ca2+. At optimal Ca2+ concentration, hydrolysis of 3-O-methylfluorescein phosphate proceeds in the presence of fluorescein isothiocyanate, is competitively inhibited by p-nitrophenyl phosphate and, in contrast to the result observed in the absence of Ca2+, it is activated by calmodulin. In marked contrast with other pseudosubstrates, hydrolysis of 3-O-methylfluorescein phosphate supports Ca2+ transport. This highly specific activity can be used as a continuous fluorescent marker or as a tool to evaluate partial steps from the reaction cycle of plasma membrane Ca2+-ATPases.
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Affiliation(s)
- Monica M Freire
- Departamento de Bioquímica Médica, Instituto de Ciências Biomédicas, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Cidade Universitária, CEP 21941-590, Rio de Janeiro, Brazil
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37
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Bordo D, Forlani F, Spallarossa A, Colnaghi R, Carpen A, Bolognesi M, Pagani S. A persulfurated cysteine promotes active site reactivity in Azotobacter vinelandii Rhodanese. Biol Chem 2001; 382:1245-52. [PMID: 11592406 DOI: 10.1515/bc.2001.155] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Active site reactivity and specificity of RhdA, a thiosulfate:cyanide sulfurtransferase (rhodanese) from Azotobacter vinelandii, have been investigated through ligand binding, site-directed mutagenesis, and X-ray crystallographic techniques, in a combined approach. In native RhdA the active site Cys230 is found persulfurated; fluorescence and sulfurtransferase activity measurements show that phosphate anions interact with Cys230 persulfide sulfur atom and modulate activity. Crystallographic analyses confirm that phosphate and hypophosphite anions react with native RhdA, removing the persulfide sulfur atom from the active site pocket. Considering that RhdA and the catalytic subunit of Cdc25 phosphatases share a common three-dimensional fold as well as active site Cys (catalytic) and Arg residues, two RhdA mutants carrying a single amino acid insertion at the active site loop were designed and their phosphatase activity tested. The crystallographic and functional results reported here show that specific sulfurtransferase or phosphatase activities are strictly related to precise tailoring of the catalytic loop structure in RhdA and Cdc25 phosphatase, respectively.
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Affiliation(s)
- D Bordo
- National Cancer Research Institute, Advanced Biotechnology Center, Genova, Italy
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38
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Jackson MD, Denu JM. Molecular reactions of protein phosphatases--insights from structure and chemistry. Chem Rev 2001; 101:2313-40. [PMID: 11749375 DOI: 10.1021/cr000247e] [Citation(s) in RCA: 168] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- M D Jackson
- Department of Biochemistry and Molecular Biology, Oregon Health Sciences University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97201, USA
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39
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Changela A, Ho C, Martins A, Shuman S, Mondragón A. Structure and mechanism of the RNA triphosphatase component of mammalian mRNA capping enzyme. EMBO J 2001; 20:2575-86. [PMID: 11350947 PMCID: PMC125469 DOI: 10.1093/emboj/20.10.2575] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The 5' capping of mammalian pre-mRNAs is initiated by RNA triphosphatase, a member of the cysteine phosphatase superfamily. Here we report the 1.65 A crystal structure of mouse RNA triphosphatase, which reveals a deep, positively charged active site pocket that can fit a 5' triphosphate end. Structural, biochemical and mutational results show that despite sharing an HCxxxxxR(S/T) motif, a phosphoenzyme intermediate and a core alpha/beta-fold with other cysteine phosphatases, the mechanism of phosphoanhydride cleavage by mammalian capping enzyme differs from that used by protein phosphatases to hydrolyze phosphomonoesters. The most significant difference is the absence of a carboxylate general acid catalyst in RNA triphosphatase. Residues conserved uniquely among the RNA phosphatase subfamily are important for function in cap formation and are likely to play a role in substrate recognition.
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Affiliation(s)
| | - C.Kiong Ho
- Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, 2153 Sheridan Road, Evanston, IL 60208-3500 and
Molecular Biology Program, Sloan-Kettering Institute, 1275 York Avenue, New York, NY 10021, USA Corresponding author e-mail:
| | - Alexandra Martins
- Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, 2153 Sheridan Road, Evanston, IL 60208-3500 and
Molecular Biology Program, Sloan-Kettering Institute, 1275 York Avenue, New York, NY 10021, USA Corresponding author e-mail:
| | - Stewart Shuman
- Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, 2153 Sheridan Road, Evanston, IL 60208-3500 and
Molecular Biology Program, Sloan-Kettering Institute, 1275 York Avenue, New York, NY 10021, USA Corresponding author e-mail:
| | - Alfonso Mondragón
- Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, 2153 Sheridan Road, Evanston, IL 60208-3500 and
Molecular Biology Program, Sloan-Kettering Institute, 1275 York Avenue, New York, NY 10021, USA Corresponding author e-mail:
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Abstract
Experimental and theoretical studies of the catalytic mechanism in protein tyrosine phosphatases and dual specific phosphatases are reviewed. The structural properties of these enzymes contributing to the efficient rate enhancement of phosphate monoester hydrolysis have been established during the last decade. There are, however, uncertainties in the interpretation of available experimental data that make the commonly assumed reaction mechanism somewhat doubtful. Theoretical calculations as well as analysis of crystal structures point towards an alternative interpretation of the ionisation state in the reactive complex.
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Affiliation(s)
- K Kolmodin
- Department of Cell and Molecular Biology, Uppsala University, Biomedical Center, P.O. Box 596, SE-75314, Uppsala, Sweden
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41
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The Regulation of Enzymatic Activity and Metabolism. Biochemistry 2001. [DOI: 10.1016/b978-012492543-4/50014-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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42
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Pestell KE, Ducruet AP, Wipf P, Lazo JS. Small molecule inhibitors of dual specificity protein phosphatases. Oncogene 2000; 19:6607-12. [PMID: 11426646 DOI: 10.1038/sj.onc.1204084] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
One hallmark of neoplasia is the deregulation of cell cycle control mechanisms, which is secondary to altered protein phosphorylation. Dual specificity protein phosphatases uniquely dephosphorylate both phosphoserines/threonines and phosphotyrosines on the same protein substrate. As a class they regulate intracellular signaling through the mitogen activated and stress activated kinases and govern cellular movement through G1/S and G2/M cell cycle checkpoints by affecting the activity of cyclin-dependent kinases. In particular, the Cdc25 phosphatases, which dephosphorylate cyclin-dependent kinases, are overexpressed in many human tumors and this increased expression is associated with a poor prognosis. In addition to expression levels, the intracellular activity of Cdc25 phosphatases is determined by their subcellular distribution and physical proximity to substrates. Small molecules that either inhibit the catalytic activity or alter the subcellular distribution of these dual specificity protein phosphatases could provide effective tools to interrogate the role of phosphorylation pathways and may afford new approaches to the management of cancer.
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Affiliation(s)
- K E Pestell
- Department of Pharmacology, University of Pittsburgh, Pennsylvania 15261, USA
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