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Postiglione AE, Adams LL, Ekhator ES, Odelade AE, Patwardhan S, Chaudhari M, Pardue AS, Kumari A, LeFever WA, Tornow OP, Kaoud TS, Neiswinger J, Jeong JS, Parsonage D, Nelson KJ, Kc DB, Furdui CM, Zhu H, Wommack AJ, Dalby KN, Dong M, Poole LB, Keyes JD, Newman RH. Hydrogen peroxide-dependent oxidation of ERK2 within its D-recruitment site alters its substrate selection. iScience 2023; 26:107817. [PMID: 37744034 PMCID: PMC10514464 DOI: 10.1016/j.isci.2023.107817] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 07/11/2023] [Accepted: 08/30/2023] [Indexed: 09/26/2023] Open
Abstract
Extracellular signal-regulated kinases 1 and 2 (ERK1/2) are dysregulated in many pervasive diseases. Recently, we discovered that ERK1/2 is oxidized by signal-generated hydrogen peroxide in various cell types. Since the putative sites of oxidation lie within or near ERK1/2's ligand-binding surfaces, we investigated how oxidation of ERK2 regulates interactions with the model substrates Sub-D and Sub-F. These studies revealed that ERK2 undergoes sulfenylation at C159 on its D-recruitment site surface and that this modification modulates ERK2 activity differentially between substrates. Integrated biochemical, computational, and mutational analyses suggest a plausible mechanism for peroxide-dependent changes in ERK2-substrate interactions. Interestingly, oxidation decreased ERK2's affinity for some D-site ligands while increasing its affinity for others. Finally, oxidation by signal-generated peroxide enhanced ERK1/2's ability to phosphorylate ribosomal S6 kinase A1 (RSK1) in HeLa cells. Together, these studies lay the foundation for examining crosstalk between redox- and phosphorylation-dependent signaling at the level of kinase-substrate selection.
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Affiliation(s)
- Anthony E. Postiglione
- Department of Biology, North Carolina A&T State University, Greensboro, NC 27411, USA
- Department of Biology, Wake Forest University, Winston-Salem, NC 27101, USA
| | - Laquaundra L. Adams
- Department of Biology, North Carolina A&T State University, Greensboro, NC 27411, USA
| | - Ese S. Ekhator
- Department of Biology, North Carolina A&T State University, Greensboro, NC 27411, USA
| | - Anuoluwapo E. Odelade
- Department of Biology, North Carolina A&T State University, Greensboro, NC 27411, USA
| | - Supriya Patwardhan
- Department of Biology, North Carolina A&T State University, Greensboro, NC 27411, USA
| | - Meenal Chaudhari
- Department of Biology, North Carolina A&T State University, Greensboro, NC 27411, USA
- Department of Computational Data Science and Engineering, North Carolina A&T State University, Greensboro, NC 27411, USA
- Department of Mathematics and Computer Science, University of Virginia at Wise, Wise, VA 24293, USA
| | - Avery S. Pardue
- Department of Biology, North Carolina A&T State University, Greensboro, NC 27411, USA
| | - Anjali Kumari
- Department of Biology, North Carolina A&T State University, Greensboro, NC 27411, USA
| | - William A. LeFever
- Department of Chemistry, High Point University, High Point, NC 27268, USA
- Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Olivia P. Tornow
- Department of Chemistry, High Point University, High Point, NC 27268, USA
| | - Tamer S. Kaoud
- Division of Chemical Biology and Medicinal Chemistry, The University of Texas at Austin, Austin, TX 78712, USA
| | - Johnathan Neiswinger
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Biology, Belhaven University, Jackson, MS 39202, USA
| | - Jun Seop Jeong
- Department of Biology, North Carolina A&T State University, Greensboro, NC 27411, USA
| | - Derek Parsonage
- Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
| | - Kimberly J. Nelson
- Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
| | - Dukka B. Kc
- Department of Computer Science, Michigan Technological University, Houghton, MI 49931, USA
| | - Cristina M. Furdui
- Department of Internal Medicine, Section on Molecular Medicine, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
| | - Heng Zhu
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Andrew J. Wommack
- Department of Chemistry, High Point University, High Point, NC 27268, USA
| | - Kevin N. Dalby
- Division of Chemical Biology and Medicinal Chemistry, The University of Texas at Austin, Austin, TX 78712, USA
| | - Ming Dong
- Department of Chemistry, North Carolina A&T State University, Greensboro, NC 27411, USA
- Department of Chemistry and Biochemistry, University of North Carolina Wilmington, Wilmington, NC 28403, USA
| | - Leslie B. Poole
- Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
| | - Jeremiah D. Keyes
- Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
- Department of Biology, Penn State University Behrend, Erie, PA 16563, USA
- Magee-Womens Research Institute, Pittsburgh, PA 15213, USA
| | - Robert H. Newman
- Department of Biology, North Carolina A&T State University, Greensboro, NC 27411, USA
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Schilling J, Schöppe J, Plückthun A. From DARPins to LoopDARPins: novel LoopDARPin design allows the selection of low picomolar binders in a single round of ribosome display. J Mol Biol 2014; 426:691-721. [PMID: 24513107 DOI: 10.1016/j.jmb.2013.10.026] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2013] [Revised: 10/17/2013] [Accepted: 10/17/2013] [Indexed: 12/19/2022]
Abstract
Antibodies are the most versatile binding proteins in nature with six loops creating a flexible continuous interaction surface. However, in some molecular formats, antibodies are aggregation prone. Designed ankyrin repeat proteins (DARPins) were successfully created as alternative design solutions. Nevertheless, their concave shape, rigidity and incompletely randomized binding surface may limit the epitopes that can be targeted by this extremely stable scaffold. Combining conformational diversity and a continuous convex paratope found in many antibodies with the beneficial biophysical properties of DARPins, we created LoopDARPins, a next generation of DARPins with extended epitope binding properties. We employed X-ray structure determination of a LoopDARPin for design validation. Biophysical characterizations show that the introduction of an elongated loop through consensus design does not decrease the stability of the scaffold,consistent with molecular dynamics simulations. Ribosome-display selections against extracellular signal-regulated kinase 2 (ERK2) and four members of the BCL-2 family (BCL-2, BCL-XL, BCL-W and MCL-1) of anti-apoptotic regulators yielded LoopDARPins with affinities in the mid-picomolar to low nanomol arrange against all targets. The BCL-2 family binders block the interaction with their natural interaction partner and will be valuable reagents to test the apoptotic response in functional assays. With the LoopDARPin scaffold, binders for BCL-2 with an affinity of 30 pM were isolated with only a single round of ribosome display,an enrichment that has not been described for any scaffold. Identical stringent one-round selections with conventional DARPins without loop yielded no binders. The LoopDARPin scaffold may become a highly valuable tool for biotechnological high-throughput applications.
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3
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Sours KM, Xiao Y, Ahn NG. Extracellular-regulated kinase 2 is activated by the enhancement of hinge flexibility. J Mol Biol 2014; 426:1925-35. [PMID: 24534729 DOI: 10.1016/j.jmb.2014.02.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 02/05/2014] [Accepted: 02/07/2014] [Indexed: 11/17/2022]
Abstract
Protein motions underlie conformational and entropic contributions to enzyme catalysis; however, relatively little is known about the ways in which this occurs. Studies of the mitogen-activated protein kinase ERK2 (extracellular-regulated protein kinase 2) by hydrogen-exchange mass spectrometry suggest that activation enhances backbone flexibility at the linker between N- and C-terminal domains while altering nucleotide binding mode. Here, we address the hypothesis that enhanced backbone flexibility within the hinge region facilitates kinase activation. We show that hinge mutations enhancing flexibility promote changes in the nucleotide binding mode consistent with domain movement, without requiring phosphorylation. They also lead to the activation of monophosphorylated ERK2, a form that is normally inactive. The hinge mutations bypass the need for pTyr but not pThr, suggesting that Tyr phosphorylation controls hinge motions. In agreement, monophosphorylation of pTyr enhances both hinge flexibility and nucleotide binding mode, measured by hydrogen-exchange mass spectrometry. Our findings demonstrate that regulated protein motions underlie kinase activation. Our working model is that constraints to domain movement in ERK2 are overcome by phosphorylation at pTyr, which increases hinge dynamics to promote the active conformation of the catalytic site.
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Affiliation(s)
- Kevin M Sours
- Department of Chemistry and Biochemistry and BioFrontiers Institute, University of Colorado, Boulder, CO 80309, USA
| | - Yao Xiao
- Department of Chemistry and Biochemistry and BioFrontiers Institute, University of Colorado, Boulder, CO 80309, USA
| | - Natalie G Ahn
- Department of Chemistry and Biochemistry and BioFrontiers Institute, University of Colorado, Boulder, CO 80309, USA; Howard Hughes Medical Institute, University of Colorado, Boulder, CO 80309, USA.
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4
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Structural and functional analysis of phosphorylation-specific binders of the kinase ERK from designed ankyrin repeat protein libraries. Proc Natl Acad Sci U S A 2012; 109:E2248-57. [PMID: 22843676 DOI: 10.1073/pnas.1205399109] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
We have selected designed ankyrin repeat proteins (DARPins) from a synthetic library by using ribosome display that selectively bind to the mitogen-activated protein kinase ERK2 (extracellular signal-regulated kinase 2) in either its nonphosphorylated (inactive) or doubly phosphorylated (active) form. They do not bind to other kinases tested. Crystal structures of complexes with two DARPins, each specific for one of the kinase forms, were obtained. The two DARPins bind to essentially the same region of the kinase, but recognize the conformational change within the activation loop and an adjacent area, which is the key structural difference that occurs upon activation. Whereas the rigid phosphorylated activation loop remains in the same form when bound by the DARPin, the more mobile unphosphorylated loop is pushed to a new position. The DARPins can be used to selectively precipitate the cognate form of the kinases from cell lysates. They can also specifically recognize the modification status of the kinase inside the cell. By fusing the kinase with Renilla luciferase and the DARPin to GFP, an energy transfer from luciferase to GFP can be observed in COS-7 cells upon intracellular complex formation. Phosphorylated ERK2 is seen to increase by incubation of the COS-7 cells with FBS and to decrease upon adding the ERK pathway inhibitor PD98509. Furthermore, the anti-ERK2 DARPin is seen to inhibit ERK phosphorylation as it blocks the target inside the cell. This strategy of creating activation-state-specific sensors and kinase-specific inhibitors may add to the repertoire to investigate intracellular signaling in real time.
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Zheng LS, Zhang YY, Wu JW, Wu Z, Zhang ZY, Wang ZX. A continuous spectrophotometric assay for mitogen-activated protein kinase kinases. Anal Biochem 2012; 421:191-7. [DOI: 10.1016/j.ab.2011.11.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 11/11/2011] [Accepted: 11/18/2011] [Indexed: 10/15/2022]
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Ring AY, Sours KM, Lee T, Ahn NG. Distinct patterns of activation-dependent changes in conformational mobility between ERK1 and ERK2. INTERNATIONAL JOURNAL OF MASS SPECTROMETRY 2011; 302:101-109. [PMID: 21785572 PMCID: PMC3139246 DOI: 10.1016/j.ijms.2010.08.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Hydrogen/deuterium exchange measurements by mass spectrometry (HX-MS) can be used to report localized conformational mobility within folded proteins, where exchange predominantly occurs through low energy fluctuations in structure, allowing transient solvent exposure. Changes in conformational mobility may impact protein function, even in cases where structural changes are unobservable. Previous studies of the MAP kinase, ERK2, revealed increases in HX upon activation occured at the hinge between conserved N- and C-terminal domains, which could be ascribed to enhanced backbone flexibility. This implied that kinase activation modulates interdomain closure, and was supported by evidence for two modes of nucleotide binding that were consistent with closed vs open conformations in active vs inactive forms of ERK2, respectively. Thus, phosphorylation of ERK2 releases constraints to interdomain closure, by modulating hinge flexibility. In this study, we examined ERK1, which shares 90% sequence identity with ERK2. HX-MS measurements of ERK1 showed similarities with ERK2 in overall deuteration, consistent with their similar tertiary structures. However, the patterns of HX that were altered upon activation of ERK1 differed from those in ERK2. In particular, alterations in HX at the hinge region upon activation of ERK2 did not occur in ERK1, suggesting that the two enzymes differ with respect to their regulation of hinge mobility and interdomain closure. In agreement, HX-MS measurements of nucleotide binding suggested revealed domain closure in both inactive and active forms of ERK1. We conclude that although ERK1 and ERK2 are closely related with respect to primary sequence and tertiary structure, they utilize distinct mechanisms for controlling enzyme function through interdomain interactions.
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Affiliation(s)
- Adam Y. Ring
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309
| | - Kevin M. Sours
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309
| | - Thomas Lee
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309
- Howard Hughes Medical Institute, University of Colorado, Boulder, CO 80309
| | - Natalie G. Ahn
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309
- Howard Hughes Medical Institute, University of Colorado, Boulder, CO 80309
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7
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Akella R, Min X, Wu Q, Gardner KH, Goldsmith EJ. The third conformation of p38α MAP kinase observed in phosphorylated p38α and in solution. Structure 2011; 18:1571-8. [PMID: 21134636 DOI: 10.1016/j.str.2010.09.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2010] [Revised: 09/01/2010] [Accepted: 09/22/2010] [Indexed: 01/22/2023]
Abstract
MAPKs engage substrates, MAP2Ks, and phosphatases via a docking groove in the C-terminal domain of the kinase. Prior crystallographic studies on the unphosphorylated MAPKs p38α and ERK2 defined the docking groove and revealed long-range conformational changes affecting the activation loop and active site of the kinase induced by peptide. Solution NMR data presented here for unphosphorylated p38α with a MEK3b-derived peptide (p38α/pepMEK3b) validate these findings. Crystallograhic data from doubly phosphorylated active p38α (p38α/T∗GY∗/pepMEK3b) reveal a structure similar to unphosphorylated p38α/MEK3b, and distinct from phosphorylated p38γ (p38γ/T∗GY∗) and ERK2 (ERK2/T∗EY∗). The structure supports the idea that MAP kinases adopt three distinct conformations: unphosphorylated, phosphorylated, and a docking peptide-induced form.
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Affiliation(s)
- Radha Akella
- Department of Biochemistry, The University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Dallas, TX 75390-8816, USA
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8
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Abstract
MAPK cascade components have been the subject of structural analysis, advancing our understanding of how these enzymes are activated and how they interact. A surprising finding has been that unique inactive conformers are adopted by many of these kinases. These inactive conformers are interesting and often require experimental phases to determine their crystal structures because molecular replacement techniques are not successful. Here, we describe the preparation of MAP2K MEK6 and MAP3K TAO2 substituted with selenomethionine (SeMet) for de novo phasing. TAO2 and SeMet TAO2 were expressed in insect cells.
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Affiliation(s)
- Elizabeth J Goldsmith
- Department of Biochemistry, The University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA.
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9
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Raf kinase inhibitory protein function is regulated via a flexible pocket and novel phosphorylation-dependent mechanism. Mol Cell Biol 2008; 29:1306-20. [PMID: 19103740 DOI: 10.1128/mcb.01271-08] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Raf kinase inhibitory protein (RKIP/PEBP1), a member of the phosphatidylethanolamine binding protein family that possesses a conserved ligand-binding pocket, negatively regulates the mammalian mitogen-activated protein kinase (MAPK) signaling cascade. Mutation of a conserved site (P74L) within the pocket leads to a loss or switch in the function of yeast or plant RKIP homologues. However, the mechanism by which the pocket influences RKIP function is unknown. Here we show that the pocket integrates two regulatory signals, phosphorylation and ligand binding, to control RKIP inhibition of Raf-1. RKIP association with Raf-1 is prevented by RKIP phosphorylation at S153. The P74L mutation increases kinase interaction and RKIP phosphorylation, enhancing Raf-1/MAPK signaling. Conversely, ligand binding to the RKIP pocket inhibits kinase interaction and RKIP phosphorylation by a noncompetitive mechanism. Additionally, ligand binding blocks RKIP association with Raf-1. Nuclear magnetic resonance studies reveal that the pocket is highly dynamic, rationalizing its capacity to interact with distinct partners and be involved in allosteric regulation. Our results show that RKIP uses a flexible pocket to integrate ligand binding- and phosphorylation-dependent interactions and to modulate the MAPK signaling pathway. This mechanism is an example of an emerging theme involving the regulation of signaling proteins and their interaction with effectors at the level of protein dynamics.
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10
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Stefanovsky VY, Moss T. The splice variants of UBF differentially regulate RNA polymerase I transcription elongation in response to ERK phosphorylation. Nucleic Acids Res 2008; 36:5093-101. [PMID: 18676449 PMCID: PMC2528179 DOI: 10.1093/nar/gkn484] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The mammalian architectural HMGB-Box transcription factor UBF is ubiquitously expressed in two variant forms as the result of a differential splicing event, that in the UBF2 deletes 37 amino acid from the second of six HMGB-boxes. Several attempts to define a function for this shorter UBF2 protein have been less than satisfactory. However, since all mammals appear to display similar levels of the longer and shorter UBF variants, it is unlikely that UBF2 is simply nonfunctional. Previously we showed that phosphorylation of UBF by the MAP-kinase ERK regulates chromatin folding and transcription elongation, explaining the rapid response of the ribosomal RNA genes to growth factors. Here we have investigated the roles the UBF variants play in the response of these genes to ERK activity. We demonstrate that the variant HMGB-box 2 of UBF2 has lost the ability to bind bent DNA and hence to induce chromatin folding. As a result it is significantly less effective than UBF1 at arresting RNAPI elongation but at the same time is more responsive to ERK phosphorylation. Thus, UBF2 functionally simulates a hemi-phosphorylated UBF whose expression may provide a means by which to tune the response of the ribosomal RNA genes to growth factor stimulation.
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Affiliation(s)
- Victor Y Stefanovsky
- Cancer Research Centre and Department of Medical Biology of Laval University, Centre de Recherche de l'Hôtel-Dieu de Québec, 9 rue McMahon, G1R 3S3 Québec, QC, Canada
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11
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Kottegoda S, Aoto PC, Sims CE, Allbritton NL. Biarsenical-tetracysteine motif as a fluorescent tag for detection in capillary electrophoresis. Anal Chem 2008; 80:5358-66. [PMID: 18522433 DOI: 10.1021/ac8003242] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Biarsenical dyes complexed to tetracysteine motifs have proven to be highly useful fluorescent dyes in labeling specific cellular proteins for microscopic imaging. Their many advantages include membrane permeability, relatively small size, stoichiometric labeling, high affinity, and an assortment of excitation/emission wavelengths. The goal of the current study was to determine whether the biarsenical labeling scheme could be extended to fluorescent detection of analytes in capillary electrophoresis. Recombinant protein or synthesized peptides containing the optimized tetracysteine motif "-C-C-P-G-C-C-" were labeled with biarsenical dyes and then analyzed by micellar electrokinetic capillary chromatography (MEKC). The biarsenical-tetracysteine complex was stable and remained fluorescent under standard MEKC conditions for peptide and protein separations. The detection limit following electrophoresis in a capillary was less than 3 x 10(-20) mol with a simple laser-induced fluorescence system. A mixture of multiple biarsenical-labeled peptides and a protein were easily resolved. Demonstrating that the label did not interfere with bioactivity, a peptide-based enzyme substrate conjugated to the tetracysteine motif and labeled with a biarsenical dye retained its ability to be phosphorylated by the parent kinase. The feasibility of using this label for chemical cytometry experiments was shown by intracellular labeling and subsequent analysis of a recombinant protein possessing the tetracysteine motif expressed in living cells. The extension of the biarsenical-tetracysteine tag to fluorescent labeling of peptides and proteins in chemical separations is a valuable addition to biochemical and cell-based investigations.
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Affiliation(s)
- Sumith Kottegoda
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, USA
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12
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Sours KM, Kwok SC, Rachidi T, Lee T, Ring A, Hoofnagle AN, Resing KA, Ahn NG. Hydrogen-exchange mass spectrometry reveals activation-induced changes in the conformational mobility of p38alpha MAP kinase. J Mol Biol 2008; 379:1075-93. [PMID: 18501927 DOI: 10.1016/j.jmb.2008.04.044] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2008] [Revised: 04/15/2008] [Accepted: 04/18/2008] [Indexed: 11/28/2022]
Abstract
Hydrogen-deuterium exchange measurements represent a powerful approach to investigating changes in conformation and conformational mobility in proteins. Here, we examine p38alpha MAP kinase (MAPK) by hydrogen-exchange (HX) mass spectrometry to determine whether changes in conformational mobility may be induced by kinase phosphorylation and activation. Factors influencing sequence coverage in the HX mass spectrometry experiment, which show that varying sampling depths, instruments, and peptide search strategies yield the highest coverage of exchangeable amides, are examined. Patterns of regional deuteration in p38alpha are consistent with tertiary structure and similar to deuteration patterns previously determined for extracellular-signal-regulated kinase (ERK) 2, indicating that MAPKs are conserved with respect to the extent of local amide HX. Activation of p38alpha alters HX in five regions, which are interpreted by comparing X-ray structures of unphosphorylated p38alpha and X-ray structures of phosphorylated p38gamma. Conformational differences account for altered HX within the activation lip, the P+1 site, and the active site. In contrast, HX alterations are ascribed to activation-induced effects on conformational mobility, within substrate-docking sites (alphaF-alphaG, beta7-beta8), the C-terminal core (alphaE), and the N-terminal core region (beta4-beta5, alphaL16, alphaC). Activation also decreases HX in a 3-10 helix at the C-terminal extension of p38alpha. Although this helix in ERK2 forms a dimerization interface that becomes protected from HX upon activation, analytical ultracentrifugation shows that this does not occur in p38alpha because both unphosphorylated and diphosphorylated forms are monomeric. Finally, HX patterns in monophosphorylated p38alpha are similar to those in unphosphorylated kinase, indicating that the major activation lip remodeling events occur only after diphosphorylation. Importantly, patterns of activation-induced HX show differences between p38alpha and ERK2 despite their similarities in overall deuteration, suggesting that although MAPKs are closely related with respect to primary sequence and tertiary structure, they have distinct mechanisms for dynamic control of enzyme function.
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Affiliation(s)
- Kevin M Sours
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO, USA
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13
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Almog T, Lazar S, Reiss N, Etkovitz N, Milch E, Rahamim N, Dobkin-Bekman M, Rotem R, Kalina M, Ramon J, Raziel A, Breitbart H, Brietbart H, Seger R, Naor Z. Identification of extracellular signal-regulated kinase 1/2 and p38 MAPK as regulators of human sperm motility and acrosome reaction and as predictors of poor spermatozoan quality. J Biol Chem 2008; 283:14479-89. [PMID: 18372245 DOI: 10.1074/jbc.m710492200] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mature spermatozoa acquire progressive motility only after ejaculation. Their journey in the female reproductive tract also includes suppression of progressive motility, reactivation, capacitation, and hyperactivation of motility (whiplash), the mechanisms of which are obscure. MAPKs are key regulatory enzymes in cell signaling, participating in diverse cellular functions such as growth, differentiation, stress, and apoptosis. Here we report that ERK1/2 and p38 MAPK are primarily localized to the tail of mature human spermatozoa. Surprisingly, c-Jun N-terminal kinase 1/2, which is thought to be ubiquitously expressed, could not be detected in mature human spermatozoa. ERK1/2 stimulation is downstream to protein kinase C (PKC) activation, which is also present in the human sperm tail (PKCbetaI and PKCepsilon). ERK1/2 stimulates and p38 inhibits forward and hyperactivated motility, respectively. Both ERK1/2 and p38 MAPK are involved in the acrosome reaction. Using a proteomic approach, we identified ARHGAP6, a RhoGAP, as an ERK substrate in PMA-stimulated human spermatozoa. Inverse correlation was obtained between the relative expression level of ERK1 or the relative activation level of p38 and sperm motility, forward progression motility, sperm morphology, and viability. Therefore, increased expression of ERK1 and activated p38 can predict poor human sperm quality.
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Affiliation(s)
- Tal Almog
- Department of Biochemistry, George S Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Israel
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14
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Wang ZX, Wu JW. The complete pathway for ERK2-catalyzed reaction. Evidence for an iso random Bi Bi mechanism. J Biol Chem 2007; 282:27678-84. [PMID: 17652083 DOI: 10.1074/jbc.m703161200] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In the present study, the enzymatic mechanism of ERK2 is re-examined by a combination of steady-state kinetic studies in the absence and presence of viscosogenic agents. Kinetic studies carried out in various concentrations of sucrose revealed that both k(cat) and k(cat)/K(m) for either ATP or EtsDelta138 were highly sensitive to solvent viscosity, suggesting that the rapid equilibrium assumption is not valid for the phosphorylation of protein substrate by ERK2. Furthermore, the kinetic analysis with the minimal random Bi Bi reaction mechanism is shown to be inconsistent with the principle of the detailed balance. This inconsistent calculation strongly suggests that there is isomerization of the enzyme-substrate ternary complex. The viscosity-dependent steady-state kinetic data are combined to establish a kinetic mechanism for the ERK2-catalyzed reaction that predicts initial reaction velocities under varying concentrations of ATP and substrate. These results complement previous structure-function studies of mitogen-activated protein kinases and provide important insight for mechanistic interpretation of the kinase functions.
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Affiliation(s)
- Zhi-Xin Wang
- Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084, China.
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15
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Zhou B, Zhang ZY. Application of hydrogen/deuterium exchange mass spectrometry to study protein tyrosine phosphatase dynamics, ligand binding, and substrate specificity. Methods 2007; 42:227-33. [PMID: 17532509 PMCID: PMC2001256 DOI: 10.1016/j.ymeth.2007.02.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2007] [Accepted: 02/13/2007] [Indexed: 01/27/2023] Open
Abstract
Protein tyrosine phosphatases (PTPs) are signaling enzymes that control a diverse array of cellular processes. Further insight into the specific functional roles of PTPs in cellular signaling requires detailed understanding of the molecular basis for substrate recognition by the PTPs. A central question is how PTPs discriminate between multiple structurally diverse substrates that they encounter in the cell. Although X-ray crystallography is capable of revealing the intimate structural details for molecular interaction, structures of higher order PTP.substrate complexes are often difficult to obtain. Hydrogen/deuterium exchange mass spectrometry (H/DX-MS) is a powerful tool for mapping protein-protein interfaces, as well as identifying conformational and dynamic perturbations in proteins. In addition, H/DX-MS enables analysis of large protein complexes at physiological concentrations and provides insight into the solution behavior of these complexes that can not be gleaned from crystal structures. We have utilized H/DX-MS to probe PTP dynamics, ligand binding, and the structural basis of substrate recognition. In this article, we review general principles of H/DX-MS technology as applied to study protein-protein interactions and dynamics. We also provide protocols for H/DX-MS successfully used in our laboratory to define the molecular basis of ERK2 substrate recognition by MKP3. Many of the aspects that we cover in detail should be applicable to the study of other PTPs with their specific targets.
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Affiliation(s)
- Bo Zhou
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN 46202, USA
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Perlson E, Michaelevski I, Kowalsman N, Ben-Yaakov K, Shaked M, Seger R, Eisenstein M, Fainzilber M. Vimentin binding to phosphorylated Erk sterically hinders enzymatic dephosphorylation of the kinase. J Mol Biol 2006; 364:938-44. [PMID: 17046786 DOI: 10.1016/j.jmb.2006.09.056] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2006] [Revised: 09/13/2006] [Accepted: 09/14/2006] [Indexed: 11/19/2022]
Abstract
Cleavage fragments of de novo synthesized vimentin were recently reported to interact with phosphorylated Erk1 and Erk2 MAP kinases (pErk) in injured sciatic nerve, thus linking pErk to a signaling complex retrogradely transported on importins and dynein. Here we clarify the structural basis for this interaction, which explains how pErk is protected from dephosphorylation while bound to vimentin. Pull-down and ELISA experiments revealed robust calcium-dependent binding of pErk to the second coiled-coil domain of vimentin, with observed affinities of binding increasing from 180 nM at 0.1 microM calcium to 15 nM at 10 microM calcium. In contrast there was little or no binding of non-phosphorylated Erk to vimentin under these conditions. Geometric and electrostatic complementarity docking generated a number of solutions wherein vimentin binding to pErk occludes the lip containing the phosphorylated residues in the kinase. Binding competition experiments with Erk peptides confirmed a solution in which vimentin covers the phosphorylation lip in pErk, interacting with residues above and below the lip. The same peptides inhibited pErk binding to the dynein complex in sciatic nerve axoplasm, and interfered with protection from phosphatases by vimentin. Thus, a soluble intermediate filament fragment interacts with a signaling kinase and protects it from dephosphorylation by calcium-dependent steric hindrance.
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Affiliation(s)
- Eran Perlson
- Department of Biological Chemistry, Weizmann Institute of Science, 76100 Rehovot, Israel
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Stefanovsky V, Langlois F, Gagnon-Kugler T, Rothblum LI, Moss T. Growth factor signaling regulates elongation of RNA polymerase I transcription in mammals via UBF phosphorylation and r-chromatin remodeling. Mol Cell 2006; 21:629-39. [PMID: 16507361 DOI: 10.1016/j.molcel.2006.01.023] [Citation(s) in RCA: 165] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2005] [Revised: 12/14/2005] [Accepted: 01/17/2006] [Indexed: 01/21/2023]
Abstract
Synthesis of the 45S rRNA by RNA polymerase I limits cell growth. Knowledge of the mechanism of its regulation is therefore key to understanding growth control. rRNA transcription is believed to be regulated solely at initiation/promoter release. However, we found that stimulation of endogenous 45S rRNA synthesis by epidermal growth factor (EGF) and serum failed to induce an increase in RNA polymerase I engagement on the rRNA genes, despite robust enhancement of 45S rRNA synthesis. Further, endogenous transcription elongation rates were measured and found to be directly proportional to 45S rRNA synthesis. Thus, elongation is a rate-limiting step for rRNA synthesis in vivo. ERK phosphorylation of the HMG boxes of UBF, an RNA polymerase I factor essential for transcription enhancement, was shown to directly regulate elongation by inducing the remodeling of ribosomal gene chromatin. The data suggest a mechanism for coordinating the cotranscriptional assembly of preribosomal particles.
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Affiliation(s)
- Victor Stefanovsky
- Cancer Research Centre and Department of Medical Biology, Laval University, Hôtel-Dieu de Québec, 11 côte du Palais, G1R 2J6 Québec, Canada
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Perlson E, Hanz S, Ben-Yaakov K, Segal-Ruder Y, Seger R, Fainzilber M. Vimentin-dependent spatial translocation of an activated MAP kinase in injured nerve. Neuron 2005; 45:715-26. [PMID: 15748847 DOI: 10.1016/j.neuron.2005.01.023] [Citation(s) in RCA: 387] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2004] [Revised: 11/16/2004] [Accepted: 01/14/2005] [Indexed: 01/26/2023]
Abstract
How are phosphorylated kinases transported over long intracellular distances, such as in the case of axon to cell body signaling after nerve injury? Here, we show that the MAP kinases Erk1 and Erk2 are phosphorylated in sciatic nerve axoplasm upon nerve injury, concomitantly with the production of soluble forms of the intermediate filament vimentin by local translation and calpain cleavage in axoplasm. Vimentin binds phosphorylated Erks (pErk), thus linking pErk to the dynein retrograde motor via direct binding of vimentin to importin beta. Injury-induced Elk1 activation and neuronal regeneration are inhibited or delayed in dorsal root ganglion neurons from vimentin null mice, and in rats treated with a MEK inhibitor or with a peptide that prevents pErk-vimentin binding. Thus, soluble vimentin enables spatial translocation of pErk by importins and dynein in lesioned nerve.
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Affiliation(s)
- Eran Perlson
- Department of Biological Chemistry, Weizmann Institute of Science, 76100 Rehovot, Israel
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Affiliation(s)
- Bo Zhou
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, USA
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Zhou B, Wang ZX, Zhao Y, Brautigan DL, Zhang ZY. The specificity of extracellular signal-regulated kinase 2 dephosphorylation by protein phosphatases. J Biol Chem 2002; 277:31818-25. [PMID: 12082107 DOI: 10.1074/jbc.m203969200] [Citation(s) in RCA: 170] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The extracellular signal-regulated protein kinase 2 (ERK2) is the founding member of a family of mitogen-activated protein kinases (MAPKs) that are central components of signal transduction pathways for cell proliferation, stress responses, and differentiation. The MAPKs are unique among the Ser/Thr protein kinases in that they require both Thr and Tyr phosphorylation for full activation. The dual phosphorylation of Thr-183 and Tyr-185 in ERK2 is catalyzed by MAPK/ERK kinase 1 (MEK1). However, the identity and relative activity of protein phosphatases that inactivate ERK2 are less well established. In this study, we performed a kinetic analysis of ERK2 dephosphorylation by protein phosphatases using a continuous spectrophotometric enzyme-coupled assay that measures the inorganic phosphate produced in the reaction. Eleven different protein phosphatases, many previously suggested to be involved in ERK2 regulation, were compared, including tyrosine-specific phosphatases (PTP1B, CD45, and HePTP), dual specificity MAPK phosphatases (VHR, MKP3, and MKP5), and Ser/Thr protein phosphatases (PP1, PP2A, PP2B, PP2C alpha, and lambda PP). The results provide biochemical evidence that protein phosphatases display exquisite specificity in their substrate recognition and implicate HePTP, MKP3, and PP2A as ERK2 phosphatases. The fact that ERK2 inactivation could be carried out by multiple specific phosphatases shows that signals can be integrated into the pathway at the phosphatase level to determine the cellular response to external stimuli. Important insights into the roles of various protein phosphatases in ERK2 kinase signaling are obtained, and further analysis of the mechanism by which different protein phosphatases recognize and inactivate MAPKs will increase our understanding of how this kinase family is regulated.
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Affiliation(s)
- Bo Zhou
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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Zhou B, Zhang ZY. The activity of the extracellular signal-regulated kinase 2 is regulated by differential phosphorylation in the activation loop. J Biol Chem 2002; 277:13889-99. [PMID: 11839761 DOI: 10.1074/jbc.m200377200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mitogen-activated protein kinases (MAP kinases) play a central role in signaling pathways initiated by extracellular stimuli such as growth factors, cytokines, and various forms of environmental stress. Full activation of the MAP kinases requires dual phosphorylation of the Thr and Tyr residues in the TXY motif of the activation loop by MAP kinase kinases. Interestingly, down-regulation of MAP kinase activity can be initiated by multiple Ser/Thr phosphatases, Tyr-specific phosphatases, and dual-specificity phosphatases. This would inevitable lead to the formation of monophosphorylated MAP kinases. However, in much of the literature investigating MAP kinase signaling, there has been the implicit assumption that the monophosphorylated forms are inactive. Thus, the significance for the need of multiple phosphatases in regulating MAP kinase activity is not clear, and the biological functions of these monophosphorylated MAP kinases are currently unknown. We have prepared extracellular signal-regulated protein kinase 2 (ERK2) in all phosphorylated forms and kinetically characterized them using two proteins (the myelin basic protein and Elk-1) and ATP as substrates. Our results revealed that a single phosphorylation in the activation loop of ERK2 produces an intermediate activity state. Thus, the catalytic efficiencies of the monophosphorylated ERK2/pY and ERK2/pT (ERK2 phosphorylated on Tyr-185 and Thr-183, respectively) are approximately 2-3 orders of magnitude higher than that of the unphosphorylated ERK2 and are only 1-2 orders of magnitude lower than that of the fully active bisphosphorylated ERK2/pTpY. This raises the possibility that the monophosphorylated ERK2s may have distinct biological roles in vivo. Different phosphorylation states in the activation loop could be linked to graded effects on a single ERK2 function. Alternatively, they could be linked to distinct ERK2 functions. Although less active than the bisphosphorylated species, the monophosphorylated ERK2s may differentially phosphorylate pathway components.
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Affiliation(s)
- Bo Zhou
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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