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Kaoud TS, Johnson WH, Ebelt ND, Piserchio A, Zamora-Olivares D, Van Ravenstein SX, Pridgen JR, Edupuganti R, Sammons R, Cano M, Warthaka M, Harger M, Tavares CDJ, Park J, Radwan MF, Ren P, Anslyn EV, Tsai KY, Ghose R, Dalby KN. Modulating multi-functional ERK complexes by covalent targeting of a recruitment site in vivo. Nat Commun 2019; 10:5232. [PMID: 31745079 PMCID: PMC6863825 DOI: 10.1038/s41467-019-12996-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2019] [Accepted: 10/10/2019] [Indexed: 12/31/2022] Open
Abstract
Recently, the targeting of ERK with ATP-competitive inhibitors has emerged as a potential clinical strategy to overcome acquired resistance to BRAF and MEK inhibitor combination therapies. In this study, we investigate an alternative strategy of targeting the D-recruitment site (DRS) of ERK. The DRS is a conserved region that lies distal to the active site and mediates ERK-protein interactions. We demonstrate that the small molecule BI-78D3 binds to the DRS of ERK2 and forms a covalent adduct with a conserved cysteine residue (C159) within the pocket and disrupts signaling in vivo. BI-78D3 does not covalently modify p38MAPK, JNK or ERK5. BI-78D3 promotes apoptosis in BRAF inhibitor-naive and resistant melanoma cells containing a BRAF V600E mutation. These studies provide the basis for designing modulators of protein-protein interactions involving ERK, with the potential to impact ERK signaling dynamics and to induce cell cycle arrest and apoptosis in ERK-dependent cancers.
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Affiliation(s)
- Tamer S Kaoud
- Division of Chemical Biology and Medicinal Chemistry, The University of Texas at Austin, Austin, TX, 78712, USA.,Department of Medicinal Chemistry, Faculty of Pharmacy, Minia University, Minia, 61519, Egypt
| | - William H Johnson
- Division of Chemical Biology and Medicinal Chemistry, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Nancy D Ebelt
- Division of Chemical Biology and Medicinal Chemistry, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Andrea Piserchio
- Department of Chemistry and Biochemistry, The City College of New York, New York, NY, USA
| | | | - Sabrina X Van Ravenstein
- Division of Chemical Biology and Medicinal Chemistry, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Jacey R Pridgen
- Division of Chemical Biology and Medicinal Chemistry, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Ramakrishna Edupuganti
- Division of Chemical Biology and Medicinal Chemistry, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Rachel Sammons
- Division of Chemical Biology and Medicinal Chemistry, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Micael Cano
- Division of Chemical Biology and Medicinal Chemistry, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Mangalika Warthaka
- Division of Chemical Biology and Medicinal Chemistry, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Matthew Harger
- Biomedical Engineering Department, The University of Texas at Austin, Austin, TX, USA
| | - Clint D J Tavares
- Department of Cancer Biology, Dana-Farber Cancer Institute and Department of Cell Biology, Harvard Medical School, Boston, MA, 02115, USA
| | - Jihyun Park
- The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Mohamed F Radwan
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, King Abdulaziz University, Jeddah, 21589, Saudi Arabia
| | - Pengyu Ren
- Biomedical Engineering Department, The University of Texas at Austin, Austin, TX, USA
| | - Eric V Anslyn
- Department of Chemistry, The University of Texas at Austin, Austin, TX, 78712, USA
| | | | - Ranajeet Ghose
- Department of Chemistry and Biochemistry, The City College of New York, New York, NY, USA.,Graduate Programs in Biochemistry, Chemistry and Physics, The Graduate Center of the City University of New York, New York, NY, 10016, USA
| | - Kevin N Dalby
- Division of Chemical Biology and Medicinal Chemistry, The University of Texas at Austin, Austin, TX, 78712, USA.
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Aly AA, El-Sheref EM, Bakheet MEM, Mourad MAE, Bräse S, Ibrahim MAA, Nieger M, Garvalov BK, Dalby KN, Kaoud TS. Design, synthesis and biological evaluation of fused naphthofuro[3,2-c] quinoline-6,7,12-triones and pyrano[3,2-c]quinoline-6,7,8,13-tetraones derivatives as ERK inhibitors with efficacy in BRAF-mutant melanoma. Bioorg Chem 2018; 82:290-305. [PMID: 30396063 DOI: 10.1016/j.bioorg.2018.10.044] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 10/19/2018] [Accepted: 10/22/2018] [Indexed: 01/26/2023]
Abstract
Approximately 60% of human cancers exhibit enhanced activity of ERK1 and ERK2, reflecting their multiple roles in tumor initiation and progression. Acquired drug resistance, especially mechanisms associated with the reactivation of the MAPK (RAF/MEK/ERK) pathway represent a major challenge to current treatments of melanoma and several other cancers. Recently, targeting ERK has evolved as a potentially attractive strategy to overcome this resistance. Herein, we report the design and synthesis of novel series of fused naphthofuro[3,2-c]quinoline-6,7,12-triones 3a-f and pyrano[3,2-c]quinoline-6,7,8,13-tetraones 5a,b and 6, as potential ERK inhibitors. New inhibitors were synthesized and identified by different spectroscopic techniques and X-ray crystallography. They were evaluated for their ability to inhibit ERK1/2 in an in vitro radioactive kinase assay. 3b and 6 inhibited ERK1 with IC50s of 0.5 and 0.19 µM, and inhibited ERK2 with IC50s of 0.6 and 0.16 µM respectively. Kinetic mechanism studies revealed that the inhibitors are ATP-competitive inhibitors where 6 inhibited ERK2 with a Ki of 0.09 µM. Six of the new inhibitors were tested for their in vitro anticancer activity against the NCI-60 panel of tumor cell lines. Compound 3b and 6 were the most potent against most of the human tumor cell lines tested. Moreover, 3b and 6 inhibited the proliferation of the BRAF mutant A375 melanoma cells with IC50s of 3.7 and 0.13 µM, respectively. In addition, they suppressed anchorage-dependent colony formation. Treatment of the A375 cell line with 3b and 6 inhibited the phosphorylation of ERK substrates p-90RSK and ELK-1 and induced apoptosis in a dose dependent manner. Finally, a molecular docking study showed the potential binding mode of 3b and 6 within the ATP catalytic binding site of ERK2.
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Affiliation(s)
- Ashraf A Aly
- Chemistry Department, Faculty of Science, Minia University, 61519 El-Minia, Egypt.
| | - Essmat M El-Sheref
- Chemistry Department, Faculty of Science, Minia University, 61519 El-Minia, Egypt
| | - Momtaz E M Bakheet
- Chemistry Department, Faculty of Science, Minia University, 61519 El-Minia, Egypt
| | - Mai A E Mourad
- Medicinal Chemistry Department, Faculty of Pharmacy, Port-Said University, Port-Said 42526, Egypt
| | - Stefan Bräse
- Institute of Toxikology and Genetics, Karlsruhe Institute of Technology, Hermann-von-Helmholtz Platz 1, Campus Nord, 76344 Eggenstein-Leopoldshafen, Germany; Institute of Toxikologie und Genetik, Hermann-von-Helmholtz Platz 1, Campus Nord, 76344 Eggenstein-Leopoldshafen, Germany
| | - Mahmoud A A Ibrahim
- Chemistry Department, Faculty of Science, Minia University, 61519 El-Minia, Egypt
| | - Martin Nieger
- Department of Chemistry, University of Helsinki, PO Box 55 (A. I. Virtasen aukio I), 00014 University of Helsinki, Finland
| | - Boyan K Garvalov
- Centre for Biomedicine and Medical Technology Mannheim, Medical Faculty Mannheim, University of Heidelberg, 68167 Mannheim, Germany
| | - Kevin N Dalby
- Division of Chemical Biology and Medicinal Chemistry, The University of Texas at Austin, Austin, TX 78712, USA
| | - Tamer S Kaoud
- Department of Medicinal Chemistry, Faculty of Pharmacy, Minia University, 61519 El Minia, Egypt; Division of Chemical Biology and Medicinal Chemistry, The University of Texas at Austin, Austin, TX 78712, USA.
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Aly AA, El-Sheref EM, Bakheet MEM, Mourad MAE, Brown AB, Bräse S, Nieger M, Ibrahim MAA. Synthesis of novel 1,2-bis-quinolinyl-1,4-naphthoquinones: ERK2 inhibition, cytotoxicity and molecular docking studies. Bioorg Chem 2018; 81:700-712. [PMID: 30268050 DOI: 10.1016/j.bioorg.2018.09.017] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Revised: 09/06/2018] [Accepted: 09/10/2018] [Indexed: 12/16/2022]
Abstract
Two novel series of N-2,3-bis(6-substituted-4-hydroxy-2-oxo-1,2-dihydroquinolin-3-yl)naphthalene-1,4-diones 3a-d and substituted N-(methyl/ethyl)bisquinolinone triethyl-ammonium salts 4e,f were successfully synthesized. The synthesized compounds were targeted as new candidates to extracellular signal-regulated kinases 1/2 (ERK1/2) with considerable antineoplastic activity. The synthesis involved the reactions of 2 equivalents of 4-hydroxy-2(1H)-quinolinones 1a-f and one equivalent of 1,4-naphthoquinone (2) in a mixture of ethanol/dimethylformamide (1:1) as a solvent and 0.5 mL Et3N. In the reaction of 6-methyl-4-hydroxyquinolone 1b with 2, a side product 4b of the second series was obtained. In general, the presence of free NH-quinolone gave a single compound of the first series, whereas reaction of N-methyl/ethyl-quinolones 1e,f with 2 enhanced the formation of compounds of the second series. The structures of the new compounds were proved by different spectroscopic techniques such as IR, NMR (2D-NMR) and mass spectra, elemental analysis, and X-ray crystallography. To further elucidate the mechanism of action of these newly synthesized compounds, compounds 3a, 3b, 4e and 4f were selected to investigate for their MAP Kinases pathway inhibition together with molecular docking using ATP-binding site of ERK2. The results revealed that compounds 3a, 3b and 4f inhibited ETS-1 phosphorylation by ERK2 in a dose dependent manner. Also, compound 4f showed highest potency for ERK2 inhibition with ATP-competitive inhibition mechanism which was confirmed by the formation of three hydrogen bond in the molecular docking studies. The synthesized compounds were then tested for their in vitro anticancer activity against the NCI-60 panel of tumor cell lines. Interestingly, the selected compounds displayed from modest to strong cytotoxic activities. Compound 3b demonstrated broad spectrum anti-tumor activity against the nine tumor sub-panels tested, while compound 3d proved to be lethal to most of the cancer cell lines as shown by their promising GI50 and TGI values in NCI in vitro five dose testing. These results revealed that the synthesized compounds can potentially serve as leads for the development of novel chemotherapeutic agents and structure improvement will be necessary for some derivatives for enhancing their cellular activities and pharmacokinetic profile.
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Affiliation(s)
- Ashraf A Aly
- Chemistry Department, Faculty of Science, Minia University, 61519 El-Minia, Egypt.
| | - Essmat M El-Sheref
- Chemistry Department, Faculty of Science, Minia University, 61519 El-Minia, Egypt
| | - Momtaz E M Bakheet
- Chemistry Department, Faculty of Science, Minia University, 61519 El-Minia, Egypt
| | - Mai A E Mourad
- Medicinal Chemistry Department, Faculty of Pharmacy, Port-Said University, Port-Said 42526, Egypt
| | - Alan B Brown
- Chemistry Department, Florida Institute of Technology, Melbourne, FL 32901, USA
| | - Stefan Bräse
- Institute of Organic Chemistry, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany; Institute of Toxikologie und Genetik, Hermann-von-Helmholtz Platz 1, Campus Nord, 76344 Eggenstein-Leopoldshafen, Germany
| | - Martin Nieger
- Department of Chemistry, University of Helsinki, P.O. Box 55 (A. I. Virtasen aukio 1), 00014 Helsinki, Finland
| | - Mahmoud A A Ibrahim
- Chemistry Department, Faculty of Science, Minia University, 61519 El-Minia, Egypt
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Pellegrini E, Palencia A, Braun L, Kapp U, Bougdour A, Belrhali H, Bowler MW, Hakimi MA. Structural Basis for the Subversion of MAP Kinase Signaling by an Intrinsically Disordered Parasite Secreted Agonist. Structure 2016; 25:16-26. [PMID: 27889209 PMCID: PMC5222587 DOI: 10.1016/j.str.2016.10.011] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 09/21/2016] [Accepted: 10/25/2016] [Indexed: 01/07/2023]
Abstract
The causative agent of toxoplasmosis, the intracellular parasite Toxoplasma gondii, delivers a protein, GRA24, into the cells it infects that interacts with the mitogen-activated protein (MAP) kinase p38α (MAPK14), leading to activation and nuclear translocation of the host kinase and a subsequent inflammatory response that controls the progress of the parasite. The purification of a recombinant complex of GRA24 and human p38α has allowed the molecular basis of this activation to be determined. GRA24 is shown to be intrinsically disordered, binding two kinases that act independently, and is the only factor required to bypass the canonical mitogen-activated protein kinase activation pathway. An adapted kinase interaction motif (KIM) forms a highly stable complex that competes with cytoplasmic regulatory partners. In addition, the recombinant complex forms a powerful in vitro tool to evaluate the specificity and effectiveness of p38α inhibitors that have advanced to clinical trials, as it provides a hitherto unavailable stable and highly active form of p38α. Toxoplasmosis controls its host immune response via a protein effector, GRA24 A recombinant complex of GRA24 and MAPK p38α demonstrates how the protein works An adapted KIM domain ensures activation and a sustained inflammatory response The recombinant complex is useful in the evaluation of p38 inhibitors
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Affiliation(s)
- Erika Pellegrini
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble, France; Unit for Virus Host Cell Interactions, Université Grenoble Alpes-EMBL-CNRS, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble, France
| | - Andrés Palencia
- IAB, Team Host-Pathogen Interactions & Immunity to Infection, INSERM U1209, CNRS UMR5309, Université Grenoble Alpes, 38700 Grenoble, France
| | - Laurence Braun
- IAB, Team Host-Pathogen Interactions & Immunity to Infection, INSERM U1209, CNRS UMR5309, Université Grenoble Alpes, 38700 Grenoble, France
| | - Ulrike Kapp
- Structural Biology Group, European Synchrotron Radiation Facility, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble, France
| | - Alexandre Bougdour
- IAB, Team Host-Pathogen Interactions & Immunity to Infection, INSERM U1209, CNRS UMR5309, Université Grenoble Alpes, 38700 Grenoble, France
| | - Hassan Belrhali
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble, France; Unit for Virus Host Cell Interactions, Université Grenoble Alpes-EMBL-CNRS, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble, France.
| | - Matthew W Bowler
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble, France; Unit for Virus Host Cell Interactions, Université Grenoble Alpes-EMBL-CNRS, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble, France.
| | - Mohamed-Ali Hakimi
- IAB, Team Host-Pathogen Interactions & Immunity to Infection, INSERM U1209, CNRS UMR5309, Université Grenoble Alpes, 38700 Grenoble, France.
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Kaoud TS, Mitra S, Lee S, Taliaferro J, Cantrell M, Linse KD, Van Den Berg CL, Dalby KN. Development of JNK2-selective peptide inhibitors that inhibit breast cancer cell migration. ACS Chem Biol 2011; 6:658-66. [PMID: 21438496 DOI: 10.1021/cb200017n] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Despite their lack of selectivity toward c-Jun N-terminal kinase (JNK) isoforms, peptides derived from the JIP (JNK Interacting Protein) scaffolds linked to the cell-penetrating peptide TAT are widely used to investigate JNK-mediated signaling events. To engineer an isoform-selective peptide inhibitor, several JIP-based peptide sequences were designed and tested. A JIP sequence connected through a flexible linker to either the N-terminus of an inverted TAT sequence (JIP(10)-Δ-TAT(i)) or to a poly arginine sequence (JIP(10)-Δ-R(9)) enabled the potent inhibition of JNK2 (IC(50) ≈ 90 nM) and exhibited 10-fold selectivity for JNK2 over JNK1 and JNK3. Examination of both peptides in HEK293 cells revealed a potent ability to inhibit the induction of both JNK activation and c-Jun phosphorylation in cells treated with anisomycin. Notably, Western blot analysis indicates that only a fraction of total JNK must be activated to elicit robust c-Jun phosphorylation. To examine the potential of each peptide to selectively modulate JNK2 signaling in vivo, their ability to inhibit the migration of Polyoma Middle-T Antigen Mammary Tumor (PyVMT) cells was assessed. PyVMTjnk2-/- cells exhibit a lower migration potential compared to PyVMTjnk2+/+ cells, and this migration potential is restored through the overexpression of GFP-JNK2α. Both JIP(10)-Δ-TAT(i) and JIP(10)-Δ-R(9) inhibit the migration of PyVMTjnk2+/+ cells and PyVMTjnk2-/- cells expressing GFP-JNK2α. However, neither peptide inhibits the migration of PyVMTjnk2-/- cells. A control form of JIP(10)-Δ-TAT(i) containing a single leucine to arginine mutation lacks ability to inhibit JNK2 in vitro cell-free and cell-based assays and does not inhibit the migration of PyVMTjnk2+/+ cells. Together, these data suggest that JIP(10)-Δ-TAT(i) and JIP(10)-Δ-R(9) inhibit the migration of PyVMT cells through the selective inhibition of JNK2. Finally, the mechanism of inhibition of a D-retro-inverso JIP peptide, previously reported to inhibit JNK, was examined and found to inhibit p38MAPKα in an in vitro cell-free assay with little propensity to inhibit JNK isoforms.
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Affiliation(s)
| | - Shreya Mitra
- The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, United States
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Zhang YY, Wu JW, Wang ZX. Mitogen-activated protein kinase (MAPK) phosphatase 3-mediated cross-talk between MAPKs ERK2 and p38alpha. J Biol Chem 2011; 286:16150-62. [PMID: 21454500 PMCID: PMC3091224 DOI: 10.1074/jbc.m110.203786] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
MAPK phosphatase 3 (MKP3) is highly specific for ERK1/2 inactivation via dephosphorylation of both phosphotyrosine and phosphothreonine critical for enzymatic activation. Here, we show that MKP3 is able to effectively dephosphorylate the phosphotyrosine, but not phosphothreonine, in the activation loop of p38α in vitro and in intact cells. The catalytic constant of the MKP3 reaction for p38α is comparable with that for ERK2. Remarkably, MKP3, ERK2, and phosphorylated p38α can form a stable ternary complex in solution, and the phosphatase activity of MKP3 toward p38α substrate is allosterically regulated by ERK2-MKP3 interaction. This suggests that MKP3 not only controls the activities of ERK2 and p38α but also mediates cross-talk between these two MAPK pathways. The crystal structure of bisphosphorylated p38α has been determined at 2.1 Å resolution. Comparisons between the phosphorylated MAPK structures reveal the molecular basis of MKP3 substrate specificity.
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Affiliation(s)
- Yuan-Yuan Zhang
- From the Ministry of Education Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing 100084, China and
| | - Jia-Wei Wu
- From the Ministry of Education Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing 100084, China and
| | - Zhi-Xin Wang
- From the Ministry of Education Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing 100084, China and ,the Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China, To whom correspondence should be addressed. Tel.: 86-10-62785505; Fax: 86-10-62792826; E-mail:
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Kaoud TS, Devkota AK, Harris R, Rana MS, Abramczyk O, Warthaka M, Lee S, Girvin ME, Riggs AF, Dalby KN. Activated ERK2 is a monomer in vitro with or without divalent cations and when complexed to the cytoplasmic scaffold PEA-15. Biochemistry 2011; 50:4568-78. [PMID: 21506533 DOI: 10.1021/bi200202y] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The extracellular signal-regulated protein kinase, ERK2, fully activated by phosphorylation and without a His(6) tag, shows little tendency to dimerize with or without either calcium or magnesium ions when analyzed by light scattering or analytical ultracentrifugation. Light scattering shows that ~90% of ERK2 is monomeric. Sedimentation equilibrium data (obtained at 4.8-11.2 μM ERK2) with or without magnesium (10 mM) are well described by an ideal one-component model with a fitted molar mass of 40180 ± 240 Da (without Mg(2+) ions) or 41290 ± 330 Da (with Mg(2+) ions). These values, close to the sequence-derived mass of 41711 Da, indicate that no significant dimerization of ERK2 occurs in solution. Analysis of sedimentation velocity data for a 15 μM solution of ERK2 with an enhanced van Holde-Weischet method determined the sedimentation coefficient (s) to be ~3.22 S for activated ERK2 with or without 10 mM MgCl(2). The frictional coefficient ratio (f/f(0)) of 1.28 calculated from the sedimentation velocity and equilibrium data is close to that expected for an ~42 kDa globular protein. The translational diffusion coefficient of ~8.3 × 10(-7) cm(2) s(-1) calculated from the experimentally determined molar mass and sedimentation coefficient agrees with the value determined by dynamic light scattering in the absence and presence of calcium or magnesium ions and a value determined by NMR spectrometry. ERK2 has been proposed to homodimerize and bind only to cytoplasmic but not nuclear proteins [Casar, B., et al. (2008) Mol. Cell 31, 708-721]. Our light scattering data show, however, that ERK2 forms a strong 1:1 complex of ~57 kDa with the cytoplasmic scaffold protein PEA-15. Thus, ERK2 binds PEA-15 as a monomer. Our data provide strong evidence that ERK2 is monomeric under physiological conditions. Analysis of the same ERK2 construct with the nonphysiological His(6) tag shows substantial dimerization under the same ionic conditions.
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Affiliation(s)
- Tamer S Kaoud
- Division of Medicinal Chemistry, University of Texas, Austin, TX 78712, USA.
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Szafranska AE, Dalby KN. Kinetic mechanism for p38 MAP kinase alpha. A partial rapid-equilibrium random-order ternary-complex mechanism for the phosphorylation of a protein substrate. FEBS J 2005; 272:4631-45. [PMID: 16156785 DOI: 10.1111/j.1742-4658.2005.04827.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
p38 Mitogen-activated protein kinase alpha (p38 MAPKalpha) is a member of the MAPK family. It is activated by cellular stresses and has a number of cellular substrates whose coordinated regulation mediates inflammatory responses. In addition, it is a useful anti-inflammatory drug target that has a high specificity for Ser-Pro or Thr-Pro motifs in proteins and contains a number of transcription factors as well as protein kinases in its catalog of known substrates. Fundamental to signal transduction research is the understanding of the kinetic mechanisms of protein kinases and other protein modifying enzymes. To achieve this end, because peptides often make only a subset of the full range of interactions made by proteins, protein substrates must be utilized to fully elucidate kinetic mechanisms. We show using an untagged highly active form of p38 MAPKalpha, expressed and purified from Escherichia coli[Szafranska AE, Luo X & Dalby KN (2005) Anal Biochem336, 1-10) that at pH 7.5, 10 mm Mg2+ and 27 degrees C p38 MAPKalpha phosphorylates ATF2Delta115 through a partial rapid-equilibrium random-order ternary-complex mechanism. This mechanism is supported by a combination of steady-state substrate and inhibition kinetics, as well as microcalorimetry and published structural studies. The steady-state kinetic experiments suggest that magnesium adenosine triphosphate (MgATP), adenylyl (beta,gamma-methylene) diphosphonic acid (MgAMP-PCP) and magnesium adenosine diphosphate (MgADP) bind p38 MAPKalpha with dissociation constants of KA = 360 microm, KI = 240 microm, and KI > 2000 microm, respectively. Calorimetry experiments suggest that MgAMP-PCP and MgADP bind the p38 MAPKalpha-ATF2Delta115 binary complex slightly more tightly than they do the free enzyme, with a dissociation constant of Kd approximately 70 microm. Interestingly, MgAMP-PCP exhibits a mixed inhibition pattern with respect to ATF2Delta115, whereas MgADP exhibits an uncompetitive-like pattern. This discrepancy occurs because MgADP, unlike MgAMP-PCP, binds the free enzyme weakly. Intriguingly, no inhibition by 2 mm adenine or 2 mm MgAMP was detected, suggesting that the presence of a beta-phosphate is essential for significant binding of an ATP analog to the enzyme. Surprisingly, we found that inhibition by the well-known p38 MAPKalpha inhibitor SB 203580 does not follow classical linear inhibition kinetics at concentrations > 100 nm, as previously suggested, demonstrating that caution must be used when interpreting kinetic experiments using this inhibitor.
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Affiliation(s)
- Anna E Szafranska
- Division of Medicinal Chemistry, University of Texas at Austin, TX 78712, USA
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Current literature in mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2005; 40:1110-21. [PMID: 16106339 DOI: 10.1002/jms.809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
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