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Welsh CL, Conklin AE, Madan LK. Crystal Structures Reveal Hidden Domain Mechanics in Protein Kinase A (PKA). BIOLOGY 2023; 12:1370. [PMID: 37997969 PMCID: PMC10669547 DOI: 10.3390/biology12111370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 10/14/2023] [Accepted: 10/20/2023] [Indexed: 11/25/2023]
Abstract
Cyclic-AMP-dependent protein kinase A (PKA) is a critical enzyme involved in various signaling pathways that plays a crucial role in regulating cellular processes including metabolism, gene transcription, cell proliferation, and differentiation. In this study, the mechanisms of allostery in PKA were investigated by analyzing the vast repertoire of crystal structures available in the RCSB database. From existing structures of murine and human PKA, we elucidated the conformational ensembles and protein dynamics that are altered in a ligand-dependent manner. Distance metrics to analyze conformations of the G-loop were proposed to delineate different states of PKA and were compared to existing structural metrics. Furthermore, ligand-dependent flexibility was investigated through normalized B'-factors to better understand the inherent dynamics in PKA. The presented study provides a contemporary approach to traditional methods in engaging the use of crystal structures for understanding protein dynamics. Importantly, our studies provide a deeper understanding into the conformational ensemble of PKA as the enzyme progresses through its catalytic cycle. These studies provide insights into kinase regulation that can be applied to both PKA individually and protein kinases as a class.
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Affiliation(s)
- Colin L. Welsh
- Department of Cellular and Molecular Pharmacology and Experimental Therapeutics, College of Medicine, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Abigail E. Conklin
- Department of Cellular and Molecular Pharmacology and Experimental Therapeutics, College of Medicine, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Lalima K. Madan
- Department of Cellular and Molecular Pharmacology and Experimental Therapeutics, College of Medicine, Medical University of South Carolina, Charleston, SC 29425, USA
- Hollings Cancer Center, Medical University of South Carolina, Charleston, SC 29425, USA
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2
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Taylor SS, Herberg FW, Veglia G, Wu J. Edmond Fischer's kinase legacy: History of the protein kinase inhibitor and protein kinase A. IUBMB Life 2023; 75:311-323. [PMID: 36855225 PMCID: PMC10050139 DOI: 10.1002/iub.2714] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 02/13/2023] [Indexed: 03/02/2023]
Abstract
Although Fischer's extraordinary career came to focus mostly on the protein phosphatases, after his co-discovery of Phosphorylase Kinase with Ed Krebs he was clearly intrigued not only by cAMP-dependent protein kinase (PKA), but also by the heat-stable, high-affinity protein kinase inhibitor (PKI). PKI is an intrinsically disordered protein that contains at its N-terminus a pseudo-substrate motif that binds synergistically and with high-affinity to the PKA catalytic (C) subunit. The sequencing and characterization of this inhibitor peptide (IP20) were validated by the structure of the PKA C-subunit solved first as a binary complex with IP20 and then as a ternary complex with ATP and two magnesium ions. A second motif, nuclear export signal (NES), was later discovered in PKI. Both motifs correspond to amphipathic helices that convey high-affinity binding. The dynamic features of full-length PKI, recently captured by NMR, confirmed that the IP20 motif becomes dynamically and sequentially ordered only in the presence of the C-subunit. The type I PKA regulatory (R) subunits also contain a pseudo-substrate ATPMg2-dependent high-affinity inhibitor sequence. PKI and PKA, especially the Cβ subunit, are highly expressed in the brain, and PKI expression is also cell cycle-dependent. In addition, PKI is now linked to several cancers. The full biological importance of PKI and PKA signaling in the brain, and their importance in cancer thus remains to be elucidated.
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Affiliation(s)
- Susan S Taylor
- Department of Pharmacology, University of California, San Diego, California, USA
- Department of Chemistry and Biochemistry, University of California, San Diego, California, USA
| | | | - Gianluigi Veglia
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Jian Wu
- Department of Pharmacology, University of California, San Diego, California, USA
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3
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Madan LK, Welsh CL, Kornev AP, Taylor SS. The "violin model": Looking at community networks for dynamic allostery. J Chem Phys 2023; 158:081001. [PMID: 36859094 PMCID: PMC9957607 DOI: 10.1063/5.0138175] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 02/03/2023] [Indexed: 02/09/2023] Open
Abstract
Allosteric regulation of proteins continues to be an engaging research topic for the scientific community. Models describing allosteric communication have evolved from focusing on conformation-based descriptors of protein structural changes to appreciating the role of internal protein dynamics as a mediator of allostery. Here, we explain a "violin model" for allostery as a contemporary method for approaching the Cooper-Dryden model based on redistribution of protein thermal fluctuations. Based on graph theory, the violin model makes use of community network analysis to functionally cluster correlated protein motions obtained from molecular dynamics simulations. This Review provides the theory and workflow of the methodology and explains the application of violin model to unravel the workings of protein kinase A.
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Affiliation(s)
- Lalima K. Madan
- Author to whom correspondence should be addressed: and . Telephone: 843.792.4525. Fax: 843.792.0481
| | - Colin L. Welsh
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, 173 Ashley Ave., Charleston, South Carolina 29425, USA
| | - Alexandr P. Kornev
- Department of Pharmacology, University of California San Diego, 9500 Gilman Drive, San Diego, California, 92093, USA
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4
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Wych DC, Aoto PC, Vu L, Wolff AM, Mobley DL, Fraser JS, Taylor SS, Wall ME. Molecular-dynamics simulation methods for macromolecular crystallography. Acta Crystallogr D Struct Biol 2023; 79:50-65. [PMID: 36601807 PMCID: PMC9815100 DOI: 10.1107/s2059798322011871] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 12/13/2022] [Indexed: 12/31/2022] Open
Abstract
It is investigated whether molecular-dynamics (MD) simulations can be used to enhance macromolecular crystallography (MX) studies. Historically, protein crystal structures have been described using a single set of atomic coordinates. Because conformational variation is important for protein function, researchers now often build models that contain multiple structures. Methods for building such models can fail, however, in regions where the crystallographic density is difficult to interpret, for example at the protein-solvent interface. To address this limitation, a set of MD-MX methods that combine MD simulations of protein crystals with conventional modeling and refinement tools have been developed. In an application to a cyclic adenosine monophosphate-dependent protein kinase at room temperature, the procedure improved the interpretation of ambiguous density, yielding an alternative water model and a revised protein model including multiple conformations. The revised model provides mechanistic insights into the catalytic and regulatory interactions of the enzyme. The same methods may be used in other MX studies to seek mechanistic insights.
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Affiliation(s)
- David C. Wych
- Computer, Computational and Statistical Sciences Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
- Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
- Department of Pharmaceutical Sciences, University of California, Irvine, Irvine, CA 92697, USA
| | - Phillip C. Aoto
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Lily Vu
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Alexander M. Wolff
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94158, USA
| | - David L. Mobley
- Department of Pharmaceutical Sciences, University of California, Irvine, Irvine, CA 92697, USA
- Department of Chemistry, University of California, Irvine, Irvine, CA 92697, USA
| | - James S. Fraser
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Susan S. Taylor
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA
| | - Michael E. Wall
- Computer, Computational and Statistical Sciences Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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5
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Zhang X, Zhao W, Zhao Y, Zhao Z, Lv Z, Zhang Z, Ren H, Wang Q, Liu M, Qian M, Du B, Qin J. Inflammatory macrophages exacerbate neutrophil-driven joint damage through ADP/P2Y 1 signaling in rheumatoid arthritis. SCIENCE CHINA-LIFE SCIENCES 2021; 65:953-968. [PMID: 34480694 DOI: 10.1007/s11427-020-1957-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 06/02/2021] [Indexed: 11/29/2022]
Abstract
Rheumatoid arthritis (RA) is a chronic autoimmune disease that primarily affects the joints and is associated with excessive immune cell infiltration. However, the complex interactions between the immune cell populations in the RA synovium remain unknown. Here, we demonstrate that inflammatory macrophages in the synovium exacerbate neutrophil-driven joint damage in RA through ADP/P2Y1 signaling. We show that extracellular ADP (eADP) and its receptors are obviously increased in synovial tissues of RA patients as well as collagen-induced arthritis (CIA) mice, and eADP enhances neutrophil infiltration into joints through macrophages producing the chemokine CXCL2, aggravating disease development. Accordingly, the arthritis mouse model had more neutrophils in inflamed joints following ADP injection, whereas P2Y1 deficiency and pharmacologic inhibition restored arthritis severity to basal levels, suggesting a dominant role of ADP/P2Y1 signaling in RA pathology. Moreover, cellular activity of ADP/P2Y1-mediated CXCL2 production was dependent on the Gαq/Ca2+-NF-κB/NFAT pathway in macrophages. Overall, this study reveals a non-redundant role of eADP as a trigger in the pathogenesis of RA through neutrophil recruitment and disrupted tissue homeostasis and function.
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Affiliation(s)
- Xiaoyu Zhang
- Changning Maternity and Infant Health Hospital and School of Life Sciences, Shanghai Key Laboratory of Regulatory Biology, East China Normal University, Shanghai, 200241, China.,Department of Orthopedics, The Eighth Affiliated Hospital, Sun Yat-sen University, Shenzhen, 510275, China
| | - Wenxiang Zhao
- Changning Maternity and Infant Health Hospital and School of Life Sciences, Shanghai Key Laboratory of Regulatory Biology, East China Normal University, Shanghai, 200241, China
| | - Yihan Zhao
- Changning Maternity and Infant Health Hospital and School of Life Sciences, Shanghai Key Laboratory of Regulatory Biology, East China Normal University, Shanghai, 200241, China
| | - Zeda Zhao
- Changning Maternity and Infant Health Hospital and School of Life Sciences, Shanghai Key Laboratory of Regulatory Biology, East China Normal University, Shanghai, 200241, China
| | - Zhangsheng Lv
- Changning Maternity and Infant Health Hospital and School of Life Sciences, Shanghai Key Laboratory of Regulatory Biology, East China Normal University, Shanghai, 200241, China
| | - Zhen Zhang
- Changning Maternity and Infant Health Hospital and School of Life Sciences, Shanghai Key Laboratory of Regulatory Biology, East China Normal University, Shanghai, 200241, China
| | - Hua Ren
- Changning Maternity and Infant Health Hospital and School of Life Sciences, Shanghai Key Laboratory of Regulatory Biology, East China Normal University, Shanghai, 200241, China
| | - Qin Wang
- Joint Center for Translational Medicine, Fengxian District Central Hospital, Shanghai, 201499, China
| | - Mingyao Liu
- Changning Maternity and Infant Health Hospital and School of Life Sciences, Shanghai Key Laboratory of Regulatory Biology, East China Normal University, Shanghai, 200241, China
| | - Min Qian
- Changning Maternity and Infant Health Hospital and School of Life Sciences, Shanghai Key Laboratory of Regulatory Biology, East China Normal University, Shanghai, 200241, China
| | - Bing Du
- Changning Maternity and Infant Health Hospital and School of Life Sciences, Shanghai Key Laboratory of Regulatory Biology, East China Normal University, Shanghai, 200241, China.
| | - Juliang Qin
- Changning Maternity and Infant Health Hospital and School of Life Sciences, Shanghai Key Laboratory of Regulatory Biology, East China Normal University, Shanghai, 200241, China.
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6
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Lorenz R, Wu J, Herberg FW, Taylor SS, Engh RA. Drugging the Undruggable: How Isoquinolines and PKA Initiated the Era of Designed Protein Kinase Inhibitor Therapeutics. Biochemistry 2021; 60:3470-3484. [PMID: 34370450 DOI: 10.1021/acs.biochem.1c00359] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
In 1984, Japanese researchers led by the biochemist Hiroyoshi Hidaka described the first synthetic protein kinase inhibitors based on an isoquinoline sulfonamide structure (Hidaka et al. Biochemistry, 1984 Oct 9; 23(21): 5036-41. doi: 10.1021/bi00316a032). These led to the first protein kinase inhibitor approved for medical use (fasudil), an inhibitor of the AGC subfamily Rho kinase. With potencies strong enough to compete against endogenous ATP, the isoquinoline compounds established the druggability of the ATP binding site. Crystal structures of their protein kinase complexes, including with cAMP-dependent protein kinase (PKA), showed interactions that, on the one hand, could mimic ATP but, on the other hand, could be optimized for high potency binding, kinase selectivity, and diversification away from adenosine. They also showed the flexibility of the glycine-rich loop, and PKA became a major prototype for crystallographic and nuclear magnetic resonance (NMR) studies of protein kinase mechanism and dynamic activity control. Since fasudil, more than 70 kinase inhibitors have been approved for clinical use, involving efforts that progressively have introduced new paradigms of data-driven drug discovery. Publicly available data alone comprise over 5000 protein kinase crystal structures and hundreds of thousands of binding data. Now, new methods, including artificial intelligence techniques and expansion of protein kinase targeting approaches, together with the expiration of patent protection for optimized inhibitor scaffolds, promise even greater advances in drug discovery. Looking back to the time of the first isoquinoline hinge binders brings the current state-of-the-art into stark contrast. Appropriately for this Perspective article, many of the milestone papers during this time were published in Biochemistry (now ACS Biochemistry).
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Affiliation(s)
- Robin Lorenz
- Department of Biochemistry, Institute for Biology, University of Kassel, Kassel 34132, Germany
| | - Jian Wu
- Department of Pharmacology, University of California, San Diego, 9400 Gilman Drive, La Jolla, California 92093-0654, United States
| | - Friedrich W Herberg
- Department of Biochemistry, Institute for Biology, University of Kassel, Kassel 34132, Germany
| | - Susan S Taylor
- Department of Pharmacology, University of California, San Diego, 9400 Gilman Drive, La Jolla, California 92093-0654, United States.,Department of Chemistry and Biochemistry, University of California, San Diego, 9400 Gilman Drive, La Jolla, California 92093-0654, United States
| | - Richard A Engh
- The Norwegian Structural Biology Centre, Department of Chemistry, UiT the Arctic University of Norway, Tromsø 9012, Norway
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Taylor SS, Wu J, Bruystens JGH, Del Rio JC, Lu TW, Kornev AP, Ten Eyck LF. From structure to the dynamic regulation of a molecular switch: A journey over 3 decades. J Biol Chem 2021; 296:100746. [PMID: 33957122 PMCID: PMC8144671 DOI: 10.1016/j.jbc.2021.100746] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 04/16/2021] [Accepted: 04/30/2021] [Indexed: 12/14/2022] Open
Abstract
It is difficult to imagine where the signaling community would be today without the Protein Data Bank. This visionary resource, established in the 1970s, has been an essential partner for sharing information between academics and industry for over 3 decades. We describe here the history of our journey with the protein kinases using cAMP-dependent protein kinase as a prototype. We summarize what we have learned since the first structure, published in 1991, why our journey is still ongoing, and why it has been essential to share our structural information. For regulation of kinase activity, we focus on the cAMP-binding protein kinase regulatory subunits. By exploring full-length macromolecular complexes, we discovered not only allostery but also an essential motif originally attributed to crystal packing. Massive genomic data on disease mutations allows us to now revisit crystal packing as a treasure chest of possible protein:protein interfaces where the biological significance and disease relevance can be validated. It provides a new window into exploring dynamic intrinsically disordered regions that previously were deleted, ignored, or attributed to crystal packing. Merging of crystallography with cryo-electron microscopy, cryo-electron tomography, NMR, and millisecond molecular dynamics simulations is opening a new world for the signaling community where those structure coordinates, deposited in the Protein Data Bank, are just a starting point!
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Affiliation(s)
- Susan S Taylor
- Department of Pharmacology, University of California at San Diego, San Diego, California, USA; Department of Chemistry and Biochemistry, University of California at San Diego, San Diego, California, USA.
| | - Jian Wu
- Department of Pharmacology, University of California at San Diego, San Diego, California, USA
| | - Jessica G H Bruystens
- Department of Pharmacology, University of California at San Diego, San Diego, California, USA
| | - Jason C Del Rio
- Department of Pharmacology, University of California at San Diego, San Diego, California, USA
| | - Tsan-Wen Lu
- Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California, USA
| | - Alexandr P Kornev
- Department of Pharmacology, University of California at San Diego, San Diego, California, USA
| | - Lynn F Ten Eyck
- Department of Chemistry and Biochemistry, University of California at San Diego, San Diego, California, USA; San Diego Supercomputer Center, University of California at San Diego, San Diego, California, USA
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8
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Umezawa K, Kii I. Druggable Transient Pockets in Protein Kinases. Molecules 2021; 26:molecules26030651. [PMID: 33513739 PMCID: PMC7865889 DOI: 10.3390/molecules26030651] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 01/23/2021] [Accepted: 01/26/2021] [Indexed: 12/29/2022] Open
Abstract
Drug discovery using small molecule inhibitors is reaching a stalemate due to low selectivity, adverse off-target effects and inevitable failures in clinical trials. Conventional chemical screening methods may miss potent small molecules because of their use of simple but outdated kits composed of recombinant enzyme proteins. Non-canonical inhibitors targeting a hidden pocket in a protein have received considerable research attention. Kii and colleagues identified an inhibitor targeting a transient pocket in the kinase DYRK1A during its folding process and termed it FINDY. FINDY exhibits a unique inhibitory profile; that is, FINDY does not inhibit the fully folded form of DYRK1A, indicating that the FINDY-binding pocket is hidden in the folded form. This intriguing pocket opens during the folding process and then closes upon completion of folding. In this review, we discuss previously established kinase inhibitors and their inhibitory mechanisms in comparison with FINDY. We also compare the inhibitory mechanisms with the growing concept of “cryptic inhibitor-binding sites.” These sites are buried on the inhibitor-unbound surface but become apparent when the inhibitor is bound. In addition, an alternative method based on cell-free protein synthesis of protein kinases may allow the discovery of small molecules that occupy these mysterious binding sites. Transitional folding intermediates would become alternative targets in drug discovery, enabling the efficient development of potent kinase inhibitors.
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Affiliation(s)
- Koji Umezawa
- Department of Biomolecular Innovation, Institute for Biomedical Sciences, Shinshu University, 8304 Minami-Minowa, Kami-ina, Nagano 399-4598, Japan;
| | - Isao Kii
- Laboratory for Drug Target Research, Faculty & Graduate School of Agriculture, Shinshu University, 8304 Minami-Minowa, Kami-ina, Nagano 399-4598, Japan
- Correspondence: ; Tel.: +81-265-77-1521
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9
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Solorza J, Recabarren R, Alzate-Morales J. Molecular Insights into the Trapping Effect of Ca 2+ in Protein Kinase A: A Molecular Dynamics Study. J Chem Inf Model 2020; 60:898-914. [PMID: 31804819 DOI: 10.1021/acs.jcim.9b00857] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Protein kinase A has become a model system for the study of kinases, and therefore, a comprehensive understanding of the underlying molecular mechanisms in its catalytic cycle is of crucial importance. One of the aspects that has received recent attention is the role that metal cofactors play in the catalytic cycle. Although Mg2+ is the well-known physiological ion used by protein kinases, Ca2+ ions can also assist the phosphoryl transfer reaction but with lower catalytic activities. This inhibitory effect has been attributed to the ability of Ca2+ to trap the reaction products at the active site, and it has been proposed as a possible regulatory mechanism of the enzyme. Thus, in order to get a clearer understanding of these molecular events, computational simulations in the product state of PKA, in the presence of Mg2+ and Ca2+ ions, were performed through molecular dynamics (MD). Different protonation states of the active site were considered in order to model the different mechanistic pathways that have been proposed. Our results show that different protonation states of the phosphorylated serine residue at the peptide substrate (pSer21), as well as the protonation state of residue Asp166, can have a marked influence on the flexibility of regions surrounding the active site. This is the case of the glycine-rich loop, a structural motif that is directly involved in the release of the products from the PKA active site. MD simulations were capable to reproduce the crystallographic conformations but also showed other conformations not previously reported in the crystal structures that may be involved in enhancing the affinity of pSP20 to PKA in the presence of Ca2+. Hydrogen bonding interactions at the PKA-pSP20 interface were influenced whether by the protonation state of the active site or by the metal cofactor used by the enzyme. Altogether, our results provide molecular aspects into the inhibitory mechanism of Ca2+ in PKA and suggest which is the most probable protonation state of the phosphorylated product at the active site.
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Affiliation(s)
- Jocelyn Solorza
- Centro de Bioinformática, Simulación y Modelado (CBSM), Facultad de Ingeniería , Universidad de Talca , 1 Poniente 1141 , Talca , Chile
| | - Rodrigo Recabarren
- Centro de Bioinformática, Simulación y Modelado (CBSM), Facultad de Ingeniería , Universidad de Talca , 1 Poniente 1141 , Talca , Chile
| | - Jans Alzate-Morales
- Centro de Bioinformática, Simulación y Modelado (CBSM), Facultad de Ingeniería , Universidad de Talca , 1 Poniente 1141 , Talca , Chile
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10
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Lu TW, Wu J, Aoto PC, Weng JH, Ahuja LG, Sun N, Cheng CY, Zhang P, Taylor SS. Two PKA RIα holoenzyme states define ATP as an isoform-specific orthosteric inhibitor that competes with the allosteric activator, cAMP. Proc Natl Acad Sci U S A 2019; 116:16347-16356. [PMID: 31363049 PMCID: PMC6697891 DOI: 10.1073/pnas.1906036116] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Protein kinase A (PKA) holoenzyme, comprised of a cAMP-binding regulatory (R)-subunit dimer and 2 catalytic (C)-subunits, is the master switch for cAMP-mediated signaling. Of the 4 R-subunits (RIα, RIβ, RIIα, RIIβ), RIα is most essential for regulating PKA activity in cells. Our 2 RIα2C2 holoenzyme states, which show different conformations with and without ATP, reveal how ATP/Mg2+ functions as a negative orthosteric modulator. Biochemical studies demonstrate how the removal of ATP primes the holoenzyme for cAMP-mediated activation. The opposing competition between ATP/cAMP is unique to RIα. In RIIβ, ATP serves as a substrate and facilitates cAMP-activation. The isoform-specific RI-holoenzyme dimer interface mediated by N3A-N3A' motifs defines multidomain cross-talk and an allosteric network that creates competing roles for ATP and cAMP. Comparisons to the RIIβ holoenzyme demonstrate isoform-specific holoenzyme interfaces and highlights distinct allosteric mechanisms for activation in addition to the structural diversity of the isoforms.
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Affiliation(s)
- Tsan-Wen Lu
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA 92093
| | - Jian Wu
- Department of Pharmacology, University of California San Diego, La Jolla, CA 92093
| | - Phillip C Aoto
- Department of Pharmacology, University of California San Diego, La Jolla, CA 92093
| | - Jui-Hung Weng
- Department of Pharmacology, University of California San Diego, La Jolla, CA 92093
| | - Lalima G Ahuja
- Department of Pharmacology, University of California San Diego, La Jolla, CA 92093
| | - Nicholas Sun
- Department of Biological Science, University of California San Diego, La Jolla, CA 92093
| | - Cecilia Y Cheng
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA 92093
| | - Ping Zhang
- Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702
| | - Susan S Taylor
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA 92093;
- Department of Pharmacology, University of California San Diego, La Jolla, CA 92093
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11
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Gerlits O, Weiss KL, Blakeley MP, Veglia G, Taylor SS, Kovalevsky A. Zooming in on protons: Neutron structure of protein kinase A trapped in a product complex. SCIENCE ADVANCES 2019; 5:eaav0482. [PMID: 30906862 PMCID: PMC6426457 DOI: 10.1126/sciadv.aav0482] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 01/31/2019] [Indexed: 05/06/2023]
Abstract
The question vis-à-vis the chemistry of phosphoryl group transfer catalyzed by protein kinases remains a major challenge. The neutron diffraction structure of the catalytic subunit of cAMP-dependent protein kinase (PKA-C) provides a more complete chemical portrait of key proton interactions at the active site. By using a high-affinity protein kinase substrate (PKS) peptide, we captured the reaction products, dephosphorylated nucleotide [adenosine diphosphate (ADP)] and phosphorylated PKS (pPKS), bound at the active site. In the complex, the phosphoryl group of the peptide is protonated, whereas the carboxyl group of the catalytic Asp166 is not. Our structure, including conserved waters, shows how the peptide links the distal parts of the cleft together, creating a network that engages the entire molecule. By comparing slow-exchanging backbone amides to those determined by the NMR analysis of PKA-C with ADP and inhibitor peptide (PKI), we identified exchangeable amides that likely distinguish catalytic and inhibited states.
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Affiliation(s)
- Oksana Gerlits
- Bredesen Center, University of Tennessee, Knoxville, TN 37996, USA
| | - Kevin L. Weiss
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Matthew P. Blakeley
- Large Scale Structures Group, Institut Laue-Langevin, Grenoble Cedex 9, 38042, France
| | - Gianluigi Veglia
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Susan S. Taylor
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA
- Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, CA 92093, USA
| | - Andrey Kovalevsky
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
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12
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Knape MJ, Ballez M, Burghardt NC, Zimmermann B, Bertinetti D, Kornev AP, Herberg FW. Divalent metal ions control activity and inhibition of protein kinases. Metallomics 2018; 9:1576-1584. [PMID: 29043344 DOI: 10.1039/c7mt00204a] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Protein kinases are key enzymes in the regulation of eukaryotic signal transduction. As metalloenzymes they employ divalent cations for catalysis and regulation. We used the catalytic (C) subunit of cAMP-dependent protein kinase (PKA) as a model protein to investigate the role of a variety of physiologically or pathophysiologically relevant divalent metal ions in distinct steps within the catalytic cycle. It is established that divalent metal ions play a crucial role in co-binding of nucleotides and also assist in catalysis. Our studies reveal that besides the physiologically highly relevant magnesium, metals like zinc and manganese can assist in phosphoryl transfer, however, only a few support efficient substrate turnover (turnover catalysis). Those trace metals allow for substrate binding and phosphotransfer but hamper product release. We further established the unique role of magnesium as the common biologically relevant divalent metal ideally enabling (co-) substrate binding and orientation. Magnesium allows stable substrate binding and, on the other hand accelerates product release, thus being extremely efficient in turnover catalysis. We extended our studies to non-catalytic functions of protein kinases looking at pseudokinases, a subfamily of protein kinases inherently lacking critical residues for catalysis. Recently, pseudokinases have been linked to human diseases. Some pseudokinases are still capable of binding metal ions, yet have lost the ability to transfer the phosphoryl group from ATP to a given substrate. Here metal ions stabilize an active like, though catalytically unproductive conformation and are therefore crucial to maintain non-catalytic function. Finally, we demonstrate for the canonical kinase PKA that the trace metal manganese alone can stabilize protein kinases in an active like conformation allowing them to bind substrates even in the absence of nucleotides.
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Affiliation(s)
- Matthias J Knape
- Department of Biochemistry, University of Kassel, 34132 Kassel, Germany.
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13
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Søberg K, Skålhegg BS. The Molecular Basis for Specificity at the Level of the Protein Kinase a Catalytic Subunit. Front Endocrinol (Lausanne) 2018; 9:538. [PMID: 30258407 PMCID: PMC6143667 DOI: 10.3389/fendo.2018.00538] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 08/24/2018] [Indexed: 12/16/2022] Open
Abstract
Assembly of multi enzyme complexes at subcellular localizations by anchoring- and scaffolding proteins represents a pivotal mechanism for achieving spatiotemporal regulation of cellular signaling after hormone receptor targeting [for review, see (1)]. In the 3' 5'-cyclic adenosine monophosphate (cAMP) dependent protein kinase (PKA) signaling pathway it is generally accepted that specificity is secured at several levels. This includes at the first level stimulation of receptors coupled to heterotrimeric G proteins which through stimulation of adenylyl cyclase (AC) forms the second messenger cAMP. Cyclic AMP has several receptors including PKA. PKA is a tetrameric holoenzyme consisting of a regulatory (R) subunit dimer and two catalytic (C) subunits. The R subunit is the receptor for cAMP and compartmentalizes cAMP signals through binding to cell and tissue-specifically expressed A kinase anchoring proteins (AKAPs). The current dogma tells that in the presence of cAMP, PKA dissociates into an R subunit dimer and two C subunits which are free to phosphorylate relevant substrates in the cytosol and nucleus. The release of the C subunit has raised the question how specificity of the cAMP and PKA signaling pathway is maintained when the C subunit no longer is attached to the R subunit-AKAP complex. An increasing body of evidence points toward a regulatory role of the cAMP and PKA signaling pathway by targeting the C subunits to various C subunit binding proteins in the cytosol and nucleus. Moreover, recent identification of isoform specific amino acid sequences, motifs and three dimensional structures have together provided new insight into how PKA at the level of the C subunit may act in a highly isoform-specific fashion. Here we discuss recent understanding of specificity of the cAMP and PKA signaling pathway based on C subunit subcellular targeting as well as evolution of the C subunit structure that may contribute to the dynamic regulation of C subunit activity.
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Affiliation(s)
- Kristoffer Søberg
- Department of Medical Genetics, Oslo University Hospital, Oslo, Norway
| | - Bjørn Steen Skålhegg
- Section for Molecular Nutrition, University of Oslo, Oslo, Norway
- *Correspondence: Bjørn Steen Skålhegg
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14
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Pérez-Gallegos A, Garcia-Viloca M, González-Lafont À, Lluch JM. Understanding how cAMP-dependent protein kinase can catalyze phosphoryl transfer in the presence of Ca2+and Sr2+: a QM/MM study. Phys Chem Chem Phys 2017; 19:10377-10394. [DOI: 10.1039/c7cp00666g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Theoretical results demonstrate for the first time at the molecular level that the overall PKAc-catalyzed phosphoryl-transfer reaction is plausible with Ca2+and Sr2+, alkaline earth metal ions other than Mg2+, which is in good agreement with experiments.
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Affiliation(s)
- Ayax Pérez-Gallegos
- Institut de Biotecnologia i de Biomedicina and Departament de Química, Universitat Autònoma de Barcelona
- 08193 Bellaterra (Barcelona)
- Spain
| | - Mireia Garcia-Viloca
- Institut de Biotecnologia i de Biomedicina and Departament de Química, Universitat Autònoma de Barcelona
- 08193 Bellaterra (Barcelona)
- Spain
| | - Àngels González-Lafont
- Institut de Biotecnologia i de Biomedicina and Departament de Química, Universitat Autònoma de Barcelona
- 08193 Bellaterra (Barcelona)
- Spain
| | - José M. Lluch
- Institut de Biotecnologia i de Biomedicina and Departament de Química, Universitat Autònoma de Barcelona
- 08193 Bellaterra (Barcelona)
- Spain
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15
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Das A, Gerlits O, Parks JM, Langan P, Kovalevsky A, Heller WT. Protein Kinase A Catalytic Subunit Primed for Action: Time-Lapse Crystallography of Michaelis Complex Formation. Structure 2015; 23:2331-2340. [PMID: 26585512 DOI: 10.1016/j.str.2015.10.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 08/31/2015] [Accepted: 10/01/2015] [Indexed: 10/22/2022]
Abstract
The catalytic subunit of the cyclic AMP-dependent protein kinase A (PKAc) catalyzes the transfer of the γ-phosphate of bound Mg2ATP to a serine or threonine residue of a protein substrate. Here, time-lapse X-ray crystallography was used to capture a series of complexes of PKAc with an oligopeptide substrate and unreacted Mg2ATP, including the Michaelis complex, that reveal important geometric rearrangements in and near the active site preceding the phosphoryl transfer reaction. Contrary to the prevailing view, Mg(2+) binds first to the M1 site as a complex with ATP and is followed by Mg(2+) binding to the M2 site. Concurrently, the target serine hydroxyl of the peptide substrate rotates away from the active site toward the bulk solvent, which breaks the hydrogen bond with D166. Lastly, the serine hydroxyl of the substrate rotates back toward D166 to form the Michaelis complex with the active site primed for phosphoryl transfer.
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Affiliation(s)
- Amit Das
- Biology & Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
| | - Oksana Gerlits
- Biology & Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Jerry M Parks
- UT/ORNL Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Paul Langan
- Biology & Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Andrey Kovalevsky
- Biology & Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - William T Heller
- Biology & Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
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16
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Knape MJ, Ahuja LG, Bertinetti D, Burghardt NC, Zimmermann B, Taylor SS, Herberg FW. Divalent Metal Ions Mg²⁺ and Ca²⁺ Have Distinct Effects on Protein Kinase A Activity and Regulation. ACS Chem Biol 2015. [PMID: 26200257 DOI: 10.1021/acschembio.5b00271] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
cAMP-dependent protein kinase (PKA) is regulated primarily in response to physiological signals while nucleotides and metals may provide fine-tuning. PKA can use different metal ions for phosphoryl transfer, yet some, like Ca(2+), do not support steady-state catalysis. Fluorescence Polarization (FP) and Surface Plasmon Resonance (SPR) were used to study inhibitor and substrate interactions with PKA. The data illustrate how metals can act differentially as a result of their inherent coordination properties. We found that Ca(2+), in contrast to Mg(2+), does not induce high-affinity binding of PKA to pseudosubstrate inhibitors. However, Ca(2+) works in a single turnover mode to allow for phosphoryl-transfer. Using a novel SPR approach, we were able to directly monitor the interaction of PKA with a substrate in the presence of Mg(2+)ATP. This allows us to depict the entire kinase reaction including complex formation as well as release of the phosphorylated substrate. In contrast to Mg(2+), Ca(2+) apparently slows down the enzymatic reaction. A focus on individual reaction steps revealed that Ca(2+) is not as efficient as Mg(2+) in stabilizing the enzyme:substrate complex. The opposite holds true for product dissociation where Mg(2+) easily releases the phospho-substrate while Ca(2+) traps both reaction products at the active site. This explains the low steady-state activity in the presence of Ca(2+). Furthermore, Ca(2+) is able to modulate kinase activity as well as inhibitor binding even in the presence of Mg(2+). We therefore hypothesize that the physiological metal ions Mg(2+) and Ca(2+) both play a role in kinase activity and regulation. Since PKA is localized close to calcium channels and may render PKA activity susceptible to Ca(2+), our data provide a possible mechanism for novel crosstalk between cAMP and calcium signaling.
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Affiliation(s)
- Matthias J. Knape
- Department
of Biochemistry, University of Kassel, 34132 Kassel, Germany
| | - Lalima G. Ahuja
- Department
of Pharmacology, University of California at San Diego, La Jolla, California 92093, United States
| | | | | | | | - Susan S. Taylor
- Department
of Pharmacology, University of California at San Diego, La Jolla, California 92093, United States
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17
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Leader DP, Milner-White EJ. Bridging of partially negative atoms by hydrogen bonds from main-chain NH groups in proteins: The crown motif. Proteins 2015; 83:2067-76. [DOI: 10.1002/prot.24923] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 08/29/2015] [Accepted: 09/01/2015] [Indexed: 11/05/2022]
Affiliation(s)
- David P. Leader
- College of Medical, Veterinary and Life Sciences, University of Glasgow; Glasgow G12 8QQ United Kingdom
| | - E. James Milner-White
- College of Medical, Veterinary and Life Sciences, University of Glasgow; Glasgow G12 8QQ United Kingdom
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18
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Boras BW, Hirakis SP, Votapka LW, Malmstrom RD, Amaro RE, McCulloch AD. Bridging scales through multiscale modeling: a case study on protein kinase A. Front Physiol 2015; 6:250. [PMID: 26441670 PMCID: PMC4563169 DOI: 10.3389/fphys.2015.00250] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 08/24/2015] [Indexed: 12/21/2022] Open
Abstract
The goal of multiscale modeling in biology is to use structurally based physico-chemical models to integrate across temporal and spatial scales of biology and thereby improve mechanistic understanding of, for example, how a single mutation can alter organism-scale phenotypes. This approach may also inform therapeutic strategies or identify candidate drug targets that might otherwise have been overlooked. However, in many cases, it remains unclear how best to synthesize information obtained from various scales and analysis approaches, such as atomistic molecular models, Markov state models (MSM), subcellular network models, and whole cell models. In this paper, we use protein kinase A (PKA) activation as a case study to explore how computational methods that model different physical scales can complement each other and integrate into an improved multiscale representation of the biological mechanisms. Using measured crystal structures, we show how molecular dynamics (MD) simulations coupled with atomic-scale MSMs can provide conformations for Brownian dynamics (BD) simulations to feed transitional states and kinetic parameters into protein-scale MSMs. We discuss how milestoning can give reaction probabilities and forward-rate constants of cAMP association events by seamlessly integrating MD and BD simulation scales. These rate constants coupled with MSMs provide a robust representation of the free energy landscape, enabling access to kinetic, and thermodynamic parameters unavailable from current experimental data. These approaches have helped to illuminate the cooperative nature of PKA activation in response to distinct cAMP binding events. Collectively, this approach exemplifies a general strategy for multiscale model development that is applicable to a wide range of biological problems.
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Affiliation(s)
- Britton W. Boras
- Department of Bioengineering, University of CaliforniaSan Diego, La Jolla, CA, USA
| | - Sophia P. Hirakis
- Department of Chemistry and Biochemistry, University of CaliforniaSan Diego, La Jolla, CA, USA
| | - Lane W. Votapka
- Department of Chemistry and Biochemistry, University of CaliforniaSan Diego, La Jolla, CA, USA
| | - Robert D. Malmstrom
- National Biomedical Computation Resource, University of CaliforniaSan Diego, La Jolla, CA, USA
| | - Rommie E. Amaro
- Department of Chemistry and Biochemistry, University of CaliforniaSan Diego, La Jolla, CA, USA
- National Biomedical Computation Resource, University of CaliforniaSan Diego, La Jolla, CA, USA
| | - Andrew D. McCulloch
- Department of Bioengineering, University of CaliforniaSan Diego, La Jolla, CA, USA
- National Biomedical Computation Resource, University of CaliforniaSan Diego, La Jolla, CA, USA
- Department of Medicine, University of CaliforniaSan Diego, La Jolla, CA, USA
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19
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Gerlits O, Tian J, Das A, Langan P, Heller WT, Kovalevsky A. Phosphoryl Transfer Reaction Snapshots in Crystals: INSIGHTS INTO THE MECHANISM OF PROTEIN KINASE A CATALYTIC SUBUNIT. J Biol Chem 2015; 290:15538-15548. [PMID: 25925954 DOI: 10.1074/jbc.m115.643213] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Indexed: 11/06/2022] Open
Abstract
To study the catalytic mechanism of phosphorylation catalyzed by cAMP-dependent protein kinase (PKA) a structure of the enzyme-substrate complex representing the Michaelis complex is of specific interest as it can shed light on the structure of the transition state. However, all previous crystal structures of the Michaelis complex mimics of the PKA catalytic subunit (PKAc) were obtained with either peptide inhibitors or ATP analogs. Here we utilized Ca(2+) ions and sulfur in place of the nucleophilic oxygen in a 20-residue pseudo-substrate peptide (CP20) and ATP to produce a close mimic of the Michaelis complex. In the ternary reactant complex, the thiol group of Cys-21 of the peptide is facing Asp-166 and the sulfur atom is positioned for an in-line phosphoryl transfer. Replacement of Ca(2+) cations with Mg(2+) ions resulted in a complex with trapped products of ATP hydrolysis: phosphate ion and ADP. The present structural results in combination with the previously reported structures of the transition state mimic and phosphorylated product complexes complete the snapshots of the phosphoryl transfer reaction by PKAc, providing us with the most thorough picture of the catalytic mechanism to date.
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Affiliation(s)
- Oksana Gerlits
- From the Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
| | - Jianhui Tian
- From the Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
| | - Amit Das
- From the Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
| | - Paul Langan
- From the Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
| | - William T Heller
- From the Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831.
| | - Andrey Kovalevsky
- From the Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831.
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20
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Kerns SJ, Agafonov RV, Cho YJ, Pontiggia F, Otten R, Pachov DV, Kutter S, Phung LA, Murphy PN, Thai V, Alber T, Hagan MF, Kern D. The energy landscape of adenylate kinase during catalysis. Nat Struct Mol Biol 2015; 22:124-31. [PMID: 25580578 PMCID: PMC4318763 DOI: 10.1038/nsmb.2941] [Citation(s) in RCA: 123] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 11/26/2014] [Indexed: 12/17/2022]
Abstract
Kinases perform phosphoryl-transfer reactions in milliseconds; without enzymes, these reactions would take about 8,000 years under physiological conditions. Despite extensive studies, a comprehensive understanding of kinase energy landscapes, including both chemical and conformational steps, is lacking. Here we scrutinize the microscopic steps in the catalytic cycle of adenylate kinase, through a combination of NMR measurements during catalysis, pre-steady-state kinetics, molecular-dynamics simulations and crystallography of active complexes. We find that the Mg(2+) cofactor activates two distinct molecular events: phosphoryl transfer (>10(5)-fold) and lid opening (10(3)-fold). In contrast, mutation of an essential active site arginine decelerates phosphoryl transfer 10(3)-fold without substantially affecting lid opening. Our results highlight the importance of the entire energy landscape in catalysis and suggest that adenylate kinases have evolved to activate key processes simultaneously by precise placement of a single, charged and very abundant cofactor in a preorganized active site.
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Affiliation(s)
- S Jordan Kerns
- Howard Hughes Medical Institute, Department of Biochemistry, Brandeis University, Waltham, Massachusetts, USA
| | - Roman V Agafonov
- Howard Hughes Medical Institute, Department of Biochemistry, Brandeis University, Waltham, Massachusetts, USA
| | - Young-Jin Cho
- Howard Hughes Medical Institute, Department of Biochemistry, Brandeis University, Waltham, Massachusetts, USA
| | - Francesco Pontiggia
- Howard Hughes Medical Institute, Department of Biochemistry, Brandeis University, Waltham, Massachusetts, USA
| | - Renee Otten
- Howard Hughes Medical Institute, Department of Biochemistry, Brandeis University, Waltham, Massachusetts, USA
| | - Dimitar V Pachov
- Howard Hughes Medical Institute, Department of Biochemistry, Brandeis University, Waltham, Massachusetts, USA
| | - Steffen Kutter
- Howard Hughes Medical Institute, Department of Biochemistry, Brandeis University, Waltham, Massachusetts, USA
| | - Lien A Phung
- Howard Hughes Medical Institute, Department of Biochemistry, Brandeis University, Waltham, Massachusetts, USA
| | - Padraig N Murphy
- Howard Hughes Medical Institute, Department of Biochemistry, Brandeis University, Waltham, Massachusetts, USA
| | - Vu Thai
- Howard Hughes Medical Institute, Department of Biochemistry, Brandeis University, Waltham, Massachusetts, USA
| | | | - Michael F Hagan
- Department of Physics, Brandeis University, Waltham, Massachusetts, USA
| | - Dorothee Kern
- Howard Hughes Medical Institute, Department of Biochemistry, Brandeis University, Waltham, Massachusetts, USA
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21
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Pérez-Gallegos A, Garcia-Viloca M, González-Lafont À, Lluch JM. A QM/MM study of Kemptide phosphorylation catalyzed by protein kinase A. The role of Asp166 as a general acid/base catalyst. Phys Chem Chem Phys 2014; 17:3497-511. [PMID: 25535906 DOI: 10.1039/c4cp03579h] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
In this work a theoretical study of the γ-phosphoryl group transfer from ATP to Ser17 of the synthetic substrate Kemptide (LRRASLG) in protein kinase A (PKA) has been carried out with a solvated model of the PKA-Mg2ATP-Kemptide system based on the X-ray crystallographic structure. We have used high levels (B3LYP/MM and MP2/MM) of theory to determine the overall reaction paths of the so-called concerted loose mechanism trying to clarify some aspects of that mechanism still under debate. Our calculations demonstrate for the first time in a complete model of the ternary system the viability of the final step of the catalytic mechanism in which the protonation of the phosphokemptide product by Asp166 takes place. Asp166 is a base catalyst that abstracts the HγSer17 of Kemptide thus facilitating the phosphoryl transfer, but it also acts as an acid catalyst by donating the proton just accepted from Ser17 to the O2γATP atom of the phosphoryl group.
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Affiliation(s)
- Ayax Pérez-Gallegos
- Institut de Biotecnologia i de Biomedicina and Departament de Química, Universitat Autònoma de Barcelona, 08193 Bellaterra (Barcelona), Spain.
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22
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Abstract
Protein kinases are dynamically regulated signaling proteins that act as switches in the cell by phosphorylating target proteins. To establish a framework for analyzing linkages between structure, function, dynamics, and allostery in protein kinases, we carried out multiple microsecond-scale molecular-dynamics simulations of protein kinase A (PKA), an exemplar active kinase. We identified residue-residue correlated motions based on the concept of mutual information and used the Girvan-Newman method to partition PKA into structurally contiguous "communities." Most of these communities included 40-60 residues and were associated with a particular protein kinase function or a regulatory mechanism, and well-known motifs based on sequence and secondary structure were often split into different communities. The observed community maps were sensitive to the presence of different ligands and provide a new framework for interpreting long-distance allosteric coupling. Communication between different communities was also in agreement with the previously defined architecture of the protein kinase core based on the "hydrophobic spine" network. This finding gives us confidence in suggesting that community analyses can be used for other protein kinases and will provide an efficient tool for structural biologists. The communities also allow us to think about allosteric consequences of mutations that are linked to disease.
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23
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Pérez-Gallegos A, Garcia-Viloca M, González-Lafont À, Lluch JM. A QM/MM study of the associative mechanism for the phosphorylation reaction catalyzed by protein kinase A and its D166A mutant. J Comput Aided Mol Des 2014; 28:1077-91. [PMID: 25129483 DOI: 10.1007/s10822-014-9786-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 08/07/2014] [Indexed: 10/24/2022]
Abstract
Here we analyze in detail the possible catalytic role of the associative mechanism in the γ-phosphoryl transfer reaction in the catalytic subunit of the mammalian cyclic AMP-dependent protein kinase (PKA) enzyme and its D166A mutant. We have used a complete solvated model of the ATP-Mg2-Kemptide/PKA system and good levels of theory (B3LYP/MM and MP2/MM) to determine several potential energy paths from different MD snapshots, and we present a deep analysis of the interaction distances and energies between ligands, metals and enzyme residues. We have also tested the electrostatic stabilization of the transition state structures localized herein with the charge balance hypothesis. Overall, the results obtained in this work reopen the discussion about the plausibility of the associative reaction pathway and highlight the proposed role of the catalytic triad Asp166-Lys168-Thr201.
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Affiliation(s)
- Ayax Pérez-Gallegos
- Departament de Química, Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain
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24
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Abstract
![]()
Although ADP release is the rate
limiting step in product turnover
by protein kinase A, the steps and motions involved in this process
are not well resolved. Here we report the apo and ADP bound structures
of the myristylated catalytic subunit of PKA at 2.9 and 3.5 Å
resolution, respectively. The ADP bound structure adopts a conformation
that does not conform to the previously characterized open, closed,
or intermediate states. In the ADP bound structure, the C-terminal
tail and Gly-rich loop are more closed than in the open state adopted
in the apo structure but are also much more open than the intermediate
or closed conformations. Furthermore, ADP binds at the active site
with only one magnesium ion, termed Mg2 from previous structures.
These structures thus support a model where ADP release proceeds through
release of the substrate and Mg1 followed by lifting of the Gly-rich
loop and disengagement of the C-terminal tail. Coupling of these two
structural elements with the release of the first metal ion fills
in a key step in the catalytic cycle that has been missing and supports
an ensemble of correlated conformational states that mediate the full
catalytic cycle for a protein kinase.
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Affiliation(s)
- Adam C Bastidas
- Department of Pharmacology, University of California, San Diego , San Diego, California 92093, United States
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25
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Leigh KN, Webster CE. Theoretical studies of cyclic adenosine monophosphate dependent protein kinase: native enzyme and ground-state and transition-state analogues. Dalton Trans 2014; 43:3039-43. [PMID: 24202867 DOI: 10.1039/c3dt52358f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The mechanisms of phosphoryl transfer enzymes have garnered considerable attention. Cyclic AMP-dependent protein kinase (cAPK) catalyzes the transfer of the γ phosphoryl group of ATP to the serine hydroxyl group of a peptide chain. Metal-containing fluoro species have been used as transition-state and ground-state analogues in a variety of phosphoryl transfer enzymes and have shed light on the nature of the requirements in the active site to catalyze phosphoryl transfer. For cAPK, we present computational studies of the mechanism of phosphoryl transfer and the structure and (19)F NMR spectra of various ground- (BeF3(-)) and transition-state (MgF3(-), AlF4(-), and AlF3(0)) analogues. With native substrate, the phosphoryl transfer proceeds through a five-coordinate phosphorane transition state, i.e., there is not a five-coordinate phosphorane intermediate. Comparisons of simulated and experimental (19)F NMR spectra show cAPK prefers a monoanionic analogue (MgF3(-) or AlF4(-)) over a neutral analogue (AlF3), supporting the charge balance hypothesis.
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Affiliation(s)
- Katherine N Leigh
- Department of Chemistry, The University of Memphis, Memphis, Tennessee 38152, USA.
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26
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Khavrutskii IV, Smith JB, Wallqvist A. Exploring chemical reaction mechanisms through harmonic Fourier beads path optimization. J Chem Phys 2013; 139:165104. [DOI: 10.1063/1.4826470] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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27
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Li Q, Zheng J, Tan H, Li X, Chen G, Jia Z. Unique kinase catalytic mechanism of AceK with a single magnesium ion. PLoS One 2013; 8:e72048. [PMID: 23977203 PMCID: PMC3747045 DOI: 10.1371/journal.pone.0072048] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Accepted: 07/06/2013] [Indexed: 11/26/2022] Open
Abstract
Isocitrate dehydrogenase kinase/phosphatase (AceK) is the founding member of the protein phosphorylation system in prokaryotes. Based on the novel and unique structural characteristics of AceK recently uncovered, we sought to understand its kinase reaction mechanism, along with other features involved in the phosphotransfer process. Herein we report density functional theory QM calculations of the mechanism of the phosphotransfer reaction catalysed by AceK. The transition states located by the QM calculations indicate that the phosphorylation reaction, catalysed by AceK, follows a dissociative mechanism with Asp457 serving as the catalytic base to accept the proton delivered by the substrate. Our results also revealed that AceK prefers a single Mg2+-containing active site in the phosphotransfer reaction. The catalytic roles of conserved residues in the active site are discussed.
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Affiliation(s)
- Quanjie Li
- College of Chemistry, Beijing Normal University, Beijing, People’s Republic of China
| | - Jimin Zheng
- College of Chemistry, Beijing Normal University, Beijing, People’s Republic of China
| | - Hongwei Tan
- College of Chemistry, Beijing Normal University, Beijing, People’s Republic of China
- * E-mail: (HT); (GC)
| | - Xichen Li
- College of Chemistry, Beijing Normal University, Beijing, People’s Republic of China
| | - Guangju Chen
- College of Chemistry, Beijing Normal University, Beijing, People’s Republic of China
- * E-mail: (HT); (GC)
| | - Zongchao Jia
- College of Chemistry, Beijing Normal University, Beijing, People’s Republic of China
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada
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Søberg K, Jahnsen T, Rognes T, Skålhegg BS, Laerdahl JK. Evolutionary paths of the cAMP-dependent protein kinase (PKA) catalytic subunits. PLoS One 2013; 8:e60935. [PMID: 23593352 PMCID: PMC3625193 DOI: 10.1371/journal.pone.0060935] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Accepted: 03/05/2013] [Indexed: 11/19/2022] Open
Abstract
3',5'-cyclic adenosine monophosphate (cAMP) dependent protein kinase or protein kinase A (PKA) has served as a prototype for the large family of protein kinases that are crucially important for signal transduction in eukaryotic cells. The PKA catalytic subunits Cα and Cβ, encoded by the two genes PRKACA and PRKACB, respectively, are among the best understood and characterized human kinases. Here we have studied the evolution of this gene family in chordates, arthropods, mollusks and other animals employing probabilistic methods and show that Cα and Cβ arose by duplication of an ancestral PKA catalytic subunit in a common ancestor of vertebrates. The two genes have subsequently been duplicated in teleost fishes. The evolution of the PRKACG retroposon in simians was also investigated. Although the degree of sequence conservation in the PKA Cα/Cβ kinase family is exceptionally high, a small set of signature residues defining Cα and Cβ subfamilies were identified. These conserved residues might be important for functions that are unique to the Cα or Cβ clades. This study also provides a good example of a seemingly simple phylogenetic problem which, due to a very high degree of sequence conservation and corresponding weak phylogenetic signals, combined with problematic nonphylogenetic signals, is nontrivial for state-of-the-art probabilistic phylogenetic methods.
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Affiliation(s)
- Kristoffer Søberg
- Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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29
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Bastidas AC, Deal MS, Steichen JM, Guo Y, Wu J, Taylor SS. Phosphoryl transfer by protein kinase A is captured in a crystal lattice. J Am Chem Soc 2013; 135:4788-98. [PMID: 23458248 PMCID: PMC3663052 DOI: 10.1021/ja312237q] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The catalytic (C) subunit of cAMP-dependent protein kinase (PKA) is a serine/threonine kinase responsible for most of the effects of cAMP signaling, and PKA serves as a prototype for the entire kinase family. Despite multiple studies of PKA, the steps involved in phosphoryl transfer, the roles of the catalytically essential magnesium ions, and the processes that govern the rate-limiting step of ADP release are unresolved. Here we identified conditions that yielded slow phosphoryl transfer of the γ-phosphate from the generally nonhydrolyzable analog of ATP, adenosine-5'-(β,γ-imido)triphosphate (AMP-PNP), onto a substrate peptide within protein crystals. By trapping both products in the crystal lattice, we now have a complete resolution profile of all the catalytic steps. One crystal structure refined to 1.55 Å resolution shows two states of the protein with 55% displaying intact AMP-PNP and an unphosphorylated substrate and 45% displaying transfer of the γ-phosphate of AMP-PNP onto the substrate peptide yielding AMP-PN and a phosphorylated substrate. Another structure refined to 2.15 Å resolution displays complete phosphoryl transfer to the substrate. These structures, in addition to trapping both products in the crystal lattice, implicate one magnesium ion, previously termed Mg2, as the more stably bound ion. Following phosphoryl transfer, Mg2 recruits a water molecule to retain an octahedral coordination geometry suggesting the strong binding character of this magnesium ion, and Mg2 remains in the active site following complete phosphoryl transfer while Mg1 is expelled. Loss of Mg1 may thus be an important part of the rate-limiting step of ADP release.
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Affiliation(s)
- Adam C. Bastidas
- Department of Pharmacology; University of California, San Diego, CA 92093, USA
| | - Michael S. Deal
- Department of Chemistry and Biochemistry; University of California, San Diego, CA 92093, USA
| | - Jon M. Steichen
- Department of Chemistry and Biochemistry; University of California, San Diego, CA 92093, USA
| | - Yurong Guo
- Department of Chemistry and Biochemistry; University of California, San Diego, CA 92093, USA
| | - Jian Wu
- Department of Chemistry and Biochemistry; University of California, San Diego, CA 92093, USA
| | - Susan S. Taylor
- Department of Pharmacology; University of California, San Diego, CA 92093, USA
- Department of Chemistry and Biochemistry; University of California, San Diego, CA 92093, USA
- Howard Hughes Medical Institute; University of California, San Diego, CA 92093, USA
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30
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31
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Simonson T, Satpati P. Simulating GTP:Mg and GDP:Mg with a simple force field: a structural and thermodynamic analysis. J Comput Chem 2012; 34:836-46. [PMID: 23280996 DOI: 10.1002/jcc.23207] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Revised: 11/12/2012] [Accepted: 11/28/2012] [Indexed: 11/06/2022]
Abstract
Di- and tri-phosphate nucleotides are essential cofactors for many proteins, usually in an Mg(2+) -bound form. Proteins like GTPases often detect the difference between NDP and NTP and respond by changing conformations. To study such complexes, simple, fixed charge force fields have been used, which allow long simulations and precise free energy calculations. The preference for NTP or NDP binding depends on many factors, including ligand structure and Mg(2+) coordination and the changes they undergo upon binding. Here, we use a simple force field to examine two Mg(2+) coordination modes for the unbound GDP and GTP: direct, or "Inner Sphere" (IS) coordination by one or more phosphate oxygens and indirect, "Outer Sphere" (OS) coordination involving one or more bridging waters. We compare GTP: and GDP:Mg binding with OS and IS coordination; combining the results with experimental data then indicates that GTP prefers the latter. We also examine different kinds of IS coordination and their sensitivity to a key force field parameter: the optimal Mg:oxygen van der Waals distance Rmin . Increasing Rmin improves the Mg:oxygen distances, the GTP: and GDP:Mg binding affinities, and the fraction of GTP:Mg with β + γ phosphate coordination, but does not improve or change the GTP/GDP affinity difference, which remains much larger than experiment. It has no effect on the free energy of GDP binding to a GTPase.
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Affiliation(s)
- Thomas Simonson
- Department of Biology, Laboratoire de Biochimie (CNRS UMR7654), Ecole Polytechnique, 91128 Palaiseau, France.
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32
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Jacobsen D, Bao ZQ, O’Brien P, Brooks CL, Young MA. Price to be paid for two-metal catalysis: magnesium ions that accelerate chemistry unavoidably limit product release from a protein kinase. J Am Chem Soc 2012; 134:15357-70. [PMID: 22891849 PMCID: PMC3446636 DOI: 10.1021/ja304419t] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Indexed: 11/28/2022]
Abstract
Incorporation of divalent metal ions into an active site is a fundamental catalytic tool used by diverse enzymes. Divalent cations are used by protein kinases to both stabilize ATP binding and accelerate chemistry. Kinetic analysis establishes that Cyclin-dependent kinase 2 (CDK2) requires simultaneous binding of two Mg(2+) ions for catalysis of phosphoryl transfer. This tool, however, comes with a price: the rate-acceleration effects are opposed by an unavoidable rate-limiting consequence of the use of two Mg(2+) ions by CDK2. The essential metal ions stabilize ADP product binding and limit the overall rate of the reaction. We demonstrate that product release is rate limiting for activated CDK2 and evaluate the effects of the two catalytically essential Mg(2+) ions on the stability of the ADP product within the active site. We present two new crystal structures of CDK2 bound to ADP showing how the phosphate groups can be coordinated by either one or two Mg(2+) ions, with the occupancy of one site in a weaker equilibrium. Molecular dynamics simulations indicate that ADP phosphate mobility is more restricted when ADP is coordinated by two Mg(2+) ions compared to one. The structural similarity between the rigid ADP·2Mg product and the cooperatively assembled transition state provides a mechanistic rational for the rate-limiting ADP release that is observed. We demonstrate that although the simultaneous binding of two Mg(2+) ions is essential for efficient phosphoryl transfer, the presence of both Mg(2+) ions in the active site also cooperatively increases ADP affinity and opposes its release. Evolution of protein kinases must have involved careful tuning of the affinity for the second Mg(2+) ion in order to balance the needs to stabilize the chemical transition state and allow timely product release. The link between Mg(2+) site affinity and activity presents a chemical handle that may be used by regulatory factors as well as explain some mutational effects.
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Affiliation(s)
- Douglas
M. Jacobsen
- Department of Computational Medicine and Bioinformatics, Department of Pharmacology, Department of Biological
Chemistry, Department of Chemistry, Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109,
United States
| | - Zhao-Qin Bao
- Department of Computational Medicine and Bioinformatics, Department of Pharmacology, Department of Biological
Chemistry, Department of Chemistry, Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109,
United States
| | - Patrick O’Brien
- Department of Computational Medicine and Bioinformatics, Department of Pharmacology, Department of Biological
Chemistry, Department of Chemistry, Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109,
United States
| | - Charles L. Brooks
- Department of Computational Medicine and Bioinformatics, Department of Pharmacology, Department of Biological
Chemistry, Department of Chemistry, Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109,
United States
| | - Matthew A. Young
- Department of Computational Medicine and Bioinformatics, Department of Pharmacology, Department of Biological
Chemistry, Department of Chemistry, Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109,
United States
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33
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Lin K, Lin J, Wu WI, Ballard J, Lee BB, Gloor SL, Vigers GPA, Morales TH, Friedman LS, Skelton N, Brandhuber BJ. An ATP-site on-off switch that restricts phosphatase accessibility of Akt. Sci Signal 2012; 5:ra37. [PMID: 22569334 DOI: 10.1126/scisignal.2002618] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The protein serine-threonine kinase Akt undergoes a substantial conformational change upon activation, which is induced by the phosphorylation of two critical regulatory residues, threonine 308 and serine 473. Paradoxically, treating cells with adenosine 5'-triphosphate (ATP)-competitive inhibitors of Akt results in increased phosphorylation of both residues. We show that binding of ATP-competitive inhibitors stabilized a conformation in which both phosphorylated sites were inaccessible to phosphatases. ATP binding also produced this protection of the phosphorylated sites, whereas interaction with its hydrolysis product adenosine 5'-diphosphate (ADP) or allosteric Akt inhibitors resulted in increased accessibility of these phosphorylated residues. ATP-competitive inhibitors mimicked ATP by targeting active Akt. Forms of Akt activated by an oncogenic mutation or myristoylation were more potently inhibited by the ATP-competitive inhibitors than was wild-type Akt. These data support a new model of kinase regulation, wherein nucleotides modulate an on-off switch in Akt through conformational changes, which is disrupted by ATP-competitive inhibitors.
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Affiliation(s)
- Kui Lin
- Genentech Inc., South San Francisco, CA 94080, USA.
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34
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Identification and characterization of novel mutations in the human gene encoding the catalytic subunit Calpha of protein kinase A (PKA). PLoS One 2012; 7:e34838. [PMID: 22514673 PMCID: PMC3325940 DOI: 10.1371/journal.pone.0034838] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Accepted: 03/06/2012] [Indexed: 01/11/2023] Open
Abstract
The genes PRKACA and PRKACB encode the principal catalytic (C) subunits of protein kinase A (PKA) Cα and Cβ, respectively. Cα is expressed in all eukaryotic tissues examined and studies of Cα knockout mice demonstrate a crucial role for Cα in normal physiology. We have sequenced exon 2 through 10 of PRKACA from the genome of 498 Norwegian donors and extracted information about PRKACA mutations from public databases. We identified four interesting nonsynonymous point mutations, Arg45Gln, Ser109Pro, Gly186Val, and Ser263Cys, in the Cα1 splice variant of the kinase. Cα variants harboring the different amino acid mutations were analyzed for kinase activity and regulatory (R) subunit binding. Whereas mutation of residues 45 and 263 did not alter catalytic activity or R subunit binding, mutation of Ser(109) significantly reduced kinase activity while R subunit binding was unaltered. Mutation of Cα Gly(186) completely abrogated kinase activity and PKA type I but not type II holoenzyme formation. Gly(186) is located in the highly conserved DFG motif of Cα and mutation of this residue to Val was predicted to result in loss of binding of ATP and Mg(2+), which may explain the kinetic inactivity. We hypothesize that individuals born with mutations of Ser(109) or Gly(186) may be faced with abnormal development and possibly severe disease.
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35
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Cheng Y, Kekenes-Huskey P, Hake J, Holst M, McCammon J, Michailova A. Multi-Scale Continuum Modeling of Biological Processes: From Molecular Electro-Diffusion to Sub-Cellular Signaling Transduction. ACTA ACUST UNITED AC 2012; 5. [PMID: 23505398 DOI: 10.1088/1749-4699/5/1/015002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
This article provides a brief review of multi-scale modeling at the molecular to cellular scale, with new results for heart muscle cells. A finite element-based simulation package (SMOL) was used to investigate the signaling transduction at molecular and sub-cellular scales (http://mccammon.ucsd.edu/smol/, http://FETK.org) by numerical solution of time-dependent Smoluchowski equations and a reaction-diffusion system. At the molecular scale, SMOL has yielded experimentally-validated estimates of the diffusion-limited association rates for the binding of acetylcholine to mouse acetylcholinesterase using crystallographic structural data. The predicted rate constants exhibit increasingly delayed steady-state times with increasing ionic strength and demonstrate the role of an enzyme's electrostatic potential in influencing ligand binding. At the sub-cellular scale, an extension of SMOL solves a non-linear, reaction-diffusion system describing Ca2+ ligand buffering and diffusion in experimentally-derived rodent ventricular myocyte geometries. Results reveal the important role for mobile and stationary Ca2+ buffers, including Ca2+ indicator dye. We found that the alterations in Ca2+-binding and dissociation rates of troponin C (TnC) and total TnC concentration modulate subcellular Ca2+ signals. Model predicts that reduced off-rate in whole troponin complex (TnC, TnI, TnT) versus reconstructed thin filaments (Tn, Tm, actin) alters cytosolic Ca2+ dynamics under control conditions or in disease-linked TnC mutations. The ultimate goal of these studies is to develop scalable methods and theories for integration of molecular-scale information into simulations of cellular-scale systems.
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Affiliation(s)
- Y Cheng
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA
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36
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Satpati P, Simonson T. Conformational selection through electrostatics: Free energy simulations of GTP and GDP binding to archaeal initiation factor 2. Proteins 2012; 80:1264-82. [PMID: 22275120 DOI: 10.1002/prot.24023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Revised: 11/29/2011] [Accepted: 12/13/2011] [Indexed: 11/05/2022]
Abstract
Archaeal Initiation Factor 2 is a GTPase involved in protein biosynthesis. In its GTP-bound, "ON" conformation, it binds an initiator tRNA and carries it to the ribosome. In its GDP-bound, "OFF" conformation, it dissociates from tRNA. To understand the specific binding of GTP and GDP and their dependence on the conformational state, molecular dynamics free energy simulations were performed. The ON state specificity was predicted to be weak, with a GTP/GDP binding free energy difference of -1 kcal/mol, favoring GTP. The OFF state specificity is larger, 4 kcal/mol, favoring GDP. The overall effects result from a competition among many interactions in several complexes. To interpret them, we use a simpler, dielectric continuum model. Several effects are robust with respect to the model details. Both nucleotides have a net negative charge, so that removing them from solvent into the binding pocket carries a desolvation penalty, which is large for the ON state, and strongly disfavors GTP binding compared to GDP. Short-range interactions between the additional GTP phosphate group and ionized sidechains in the binding pocket offset most, but not all of the desolvation penalty; more distant groups also contribute significantly, and the switch 1 loop only slightly. The desolvation penalty is lower for the more open, wetter OFF state, and the GTP/GDP difference much smaller. Short-range interactions in the binding pocket and with more distant groups again make a significant contribution. Overall, the simulations help explain how conformational selection is achieved with a single phosphate group.
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Affiliation(s)
- Priyadarshi Satpati
- Laboratoire de Biochimie (CNRS UMR7654), Department of Biology, Ecole Polytechnique, CNRS, 91128 Palaiseau Cedex, France
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37
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Chan TO, Pascal JM, Armen RS, Rodeck U. Autoregulation of kinase dephosphorylation by ATP binding in AGC protein kinases. Cell Cycle 2012; 11:475-8. [PMID: 22262182 DOI: 10.4161/cc.11.3.19059] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
AGC kinases, including the three Akt (protein kinase B) isoforms, protein kinase A (PKA) and all protein kinase C (PKC) isoforms, require activation loop phosphorylation (threonine 308 in Akt1) as well as phosphorylation of a C-terminal residue (serine 473 in Akt1) for catalytic activity and phosphorylation of downstream targets. Conversely, phosphatases reverse these phosphorylations. Virtually all cellular processes are affected by AGC kinases, a circumstance that has led to intense scrutiny of the molecular mechanisms that regulate phosphorylation of these kinases. Here, we review a new layer of control of phosphorylation in Akt, PKA and PKC pointing to ATP binding pocket occupancy as a means to decelerate dephosphorylation of these and, potentially, other kinases. This additional level of kinase regulation opens the door to search for new functional motifs for the rational design of non- ATP-competitive kinase inhibitors that discriminate within and between protein kinase families.
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Affiliation(s)
- Tung O Chan
- Center for Translational Medicine, Department of Medicine, School of Pharmacy, Thomas Jefferson University, Philadelphia, PA, USA.
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38
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Satpati P, Simonson T. Conformational selection by the aIF2 GTPase: a molecular dynamics study of functional pathways. Biochemistry 2011; 51:353-61. [PMID: 22165972 DOI: 10.1021/bi201675n] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Archaeal initiation factor 2 (aIF2) is a GTPase involved in protein biosynthesis. In its GTP-bound, "ON" conformation, it binds an initiator tRNA and carries it to the ribosome. In its GDP-bound, "OFF" conformation, it dissociates from tRNA. To improve our understanding of the role of each conformational state in the aIF2 "life cycle", we start from the state immediately after GTP hydrolysis, ON:GDP:P(i) (where P(i) is inorganic phosphate), and consider the possible next steps on the pathway to the OFF:GDP product. The first possibility is P(i) dissociation, leading to ON:GDP, which could then relax into OFF:GDP. We use molecular dynamics simulations to compute the P(i) dissociation free energy and show that dissociation is highly favorable. The second possibility is conformational relaxation into the OFF state before P(i) dissociation, to form OFF:GDP:P(i). We estimate the corresponding free energy approximately, 2 ± 3.5 kcal/mol, so that this is an uphill or weakly downhill process. A third possibility is relaxation into another conformation, neither ON nor OFF. Indeed, a third, "MIXED" conformation was seen recently in a crystal structure of the aIF2:GDP:P(i) complex. For this conformational state, P(i) dissociation is weakly unfavorable, in contrast to the ON and OFF states. From this, we will deduce that if the MIXED:GDP complex is not too unstable, the ON:GDP:P(i) → MIXED:GDP:P(i) transformation is a downhill process, which can occur spontaneously. This suggests that the MIXED state could be a functional intermediate.
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Affiliation(s)
- Priyadarshi Satpati
- Laboratoire de Biochimie (CNRS UMR7654), Department of Biology, Ecole Polytechnique, 91128 Palaiseau, France
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39
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Resistance of Akt kinases to dephosphorylation through ATP-dependent conformational plasticity. Proc Natl Acad Sci U S A 2011; 108:E1120-7. [PMID: 22031698 DOI: 10.1073/pnas.1109879108] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Phosphorylation of a threonine residue (T308 in Akt1) in the activation loop of Akt kinases is a prerequisite for deregulated Akt activity frequently observed in neoplasia. Akt phosphorylation in vivo is balanced by the opposite activities of kinases and phosphatases. Here we describe that targeting Akt kinase to the cell membrane markedly reduced sensitivity of phosphorylated Akt to dephosphorylation by protein phosphatase 2A. This effect was amplified by occupancy of the ATP binding pocket by either ATP or ATP-competitive inhibitors. Mutational analysis revealed that R273 in Akt1 and the corresponding R274 in Akt2 are essential for shielding T308 in the activation loop against dephosphorylation. Thus, occupancy of the nucleotide binding pocket of Akt kinases enables intramolecular interactions that restrict phosphatase access and sustain Akt phosphorylation. This mechanism provides an explanation for the "paradoxical" Akt hyperphosphorylation induced by ATP-competitive inhibitor, A-443654. The lack of phosphatase resistance further contributes insight into the mechanism by which the human Akt2 R274H missense mutation may cause autosomal-dominant diabetes mellitus.
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40
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Bao ZQ, Jacobsen DM, Young MA. Briefly bound to activate: transient binding of a second catalytic magnesium activates the structure and dynamics of CDK2 kinase for catalysis. Structure 2011; 19:675-90. [PMID: 21565702 DOI: 10.1016/j.str.2011.02.016] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Revised: 01/26/2011] [Accepted: 02/07/2011] [Indexed: 01/14/2023]
Abstract
We have determined high-resolution crystal structures of a CDK2/Cyclin A transition state complex bound to ADP, substrate peptide, and MgF(3)(-). Compared to previous structures of active CDK2, the catalytic subunit of the kinase adopts a more closed conformation around the active site and now allows observation of a second Mg(2+) ion in the active site. Coupled with a strong [Mg(2+)] effect on in vitro kinase activity, the structures suggest that the transient binding of the second Mg(2+) ion is necessary to achieve maximum rate enhancement of the chemical reaction, and Mg(2+) concentration could represent an important regulator of CDK2 activity in vivo. Molecular dynamics simulations illustrate how the simultaneous binding of substrate peptide, ATP, and two Mg(2+) ions is able to induce a more rigid and closed organization of the active site that functions to orient the phosphates, stabilize the buildup of negative charge, and shield the subsequently activated γ-phosphate from solvent.
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Affiliation(s)
- Zhao Qin Bao
- Department of Biological Chemistry and the Bioinformatics Program, The University of Michigan Medical School, Ann Arbor, MI 48109, USA
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41
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Reese ML, Boothroyd JC. A conserved non-canonical motif in the pseudoactive site of the ROP5 pseudokinase domain mediates its effect on Toxoplasma virulence. J Biol Chem 2011; 286:29366-29375. [PMID: 21708941 PMCID: PMC3190742 DOI: 10.1074/jbc.m111.253435] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Revised: 06/21/2011] [Indexed: 11/06/2022] Open
Abstract
The ROP5 family is a closely related set of polymorphic pseudokinases that are critical to the ability of Toxoplasma to cause disease. Polymorphisms in ROP5 also make it a major determinant of strain-specific differences in virulence. ROP5 possesses all of the major kinase motifs required for catalysis except for a substitution at the catalytic Asp. We show that this substitution in the catalytic loop of ROP5 is part of a motif conserved in other pseudokinases of both Toxoplasma and human origin, and that this motif is required for the full activity in vivo of ROP5. This suggests evolutionary selection at this site for a biochemical function, rather than simple drift away from catalysis. We present the crystal structures of a virulent isoform of ROP5 both in its ATP-bound and -unbound states and have demonstrated that despite maintaining the canonical ATP-binding motifs, ROP5 binds ATP in a distorted conformation mediated by unusual magnesium coordination sites that would not be predicted from the primary sequence. In addition, we have mapped the polymorphisms spread throughout the primary sequence of ROP5 to two major surfaces, including the activation segment of ROP5. This suggests that the pseudoactive site of this class of pseudokinases may have evolved to use the canonical ATP-binding motifs for non-catalytic signaling through allostery.
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Affiliation(s)
- Michael L Reese
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California 94305-5124
| | - John C Boothroyd
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California 94305-5124.
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42
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Satpati P, Clavaguéra C, Ohanessian G, Simonson T. Free energy simulations of a GTPase: GTP and GDP binding to archaeal initiation factor 2. J Phys Chem B 2011; 115:6749-63. [PMID: 21534562 PMCID: PMC3097523 DOI: 10.1021/jp201934p] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Revised: 04/13/2011] [Indexed: 12/16/2022]
Abstract
Archaeal initiation factor 2 (aIF2) is a protein involved in the initiation of protein biosynthesis. In its GTP-bound, "ON" conformation, aIF2 binds an initiator tRNA and carries it to the ribosome. In its GDP-bound, "OFF" conformation, it dissociates from tRNA. To understand the specific binding of GTP and GDP and its dependence on the ON or OFF conformational state of aIF2, molecular dynamics free energy simulations (MDFE) are a tool of choice. However, the validity of the computed free energies depends on the simulation model, including the force field and the boundary conditions, and on the extent of conformational sampling in the simulations. aIF2 and other GTPases present specific difficulties; in particular, the nucleotide ligand coordinates a divalent Mg(2+) ion, which can polarize the electronic distribution of its environment. Thus, a force field with an explicit treatment of electronic polarizability could be necessary, rather than a simpler, fixed charge force field. Here, we begin by comparing a fixed charge force field to quantum chemical calculations and experiment for Mg(2+):phosphate binding in solution, with the force field giving large errors. Next, we consider GTP and GDP bound to aIF2 and we compare two fixed charge force fields to the recent, polarizable, AMOEBA force field, extended here in a simple, approximate manner to include GTP. We focus on a quantity that approximates the free energy to change GTP into GDP. Despite the errors seen for Mg(2+):phosphate binding in solution, we observe a substantial cancellation of errors when we compare the free energy change in the protein to that in solution, or when we compare the protein ON and OFF states. Finally, we have used the fixed charge force field to perform MDFE simulations and alchemically transform GTP into GDP in the protein and in solution. With a total of about 200 ns of molecular dynamics, we obtain good convergence and a reasonable statistical uncertainty, comparable to the force field uncertainty, and somewhat lower than the predicted GTP/GDP binding free energy differences. The sign and magnitudes of the differences can thus be interpreted at a semiquantitative level, and are found to be consistent with the experimental binding preferences of ON- and OFF-aIF2.
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Affiliation(s)
- Priyadarshi Satpati
- Laboratoire de Biochimie (CNRS UMR7654), Department of Biology, Ecole Polytechnique, CNRS, 91128 Palaiseau Cedex (France)
| | - Carine Clavaguéra
- Laboratoire des Mécanismes Réactionnels (CNRS), Department of Chemistry, Ecole Polytechnique, CNRS, 91128 Palaiseau Cedex (France)
| | - Gilles Ohanessian
- Laboratoire des Mécanismes Réactionnels (CNRS), Department of Chemistry, Ecole Polytechnique, CNRS, 91128 Palaiseau Cedex (France)
| | - Thomas Simonson
- Laboratoire de Biochimie (CNRS UMR7654), Department of Biology, Ecole Polytechnique, CNRS, 91128 Palaiseau Cedex (France)
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43
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Dynamically committed, uncommitted, and quenched states encoded in protein kinase A revealed by NMR spectroscopy. Proc Natl Acad Sci U S A 2011; 108:6969-74. [PMID: 21471451 DOI: 10.1073/pnas.1102701108] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Protein kinase A (PKA) is a ubiquitous phosphoryl transferase that mediates hundreds of cell signaling events. During turnover, its catalytic subunit (PKA-C) interconverts between three major conformational states (open, intermediate, and closed) that are dynamically and allosterically activated by nucleotide binding. We show that the structural transitions between these conformational states are minimal and allosteric dynamics encode the motions from one state to the next. NMR and molecular dynamics simulations define the energy landscape of PKA-C, with the substrate allowing the enzyme to adopt a broad distribution of conformations (dynamically committed state) and the inhibitors (high magnesium and pseudosubstrate) locking it into discrete minima (dynamically quenched state), thereby reducing the motions that allow turnover. These results unveil the role of internal dynamics in both kinase function and regulation.
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