1
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Nam K, Thodika ARA, Tischlik S, Phoeurk C, Nagy TM, Schierholz L, Ådén J, Rogne P, Drescher M, Sauer-Eriksson AE, Wolf-Watz M. Magnesium induced structural reorganization in the active site of adenylate kinase. SCIENCE ADVANCES 2024; 10:eado5504. [PMID: 39121211 PMCID: PMC11313852 DOI: 10.1126/sciadv.ado5504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Accepted: 07/08/2024] [Indexed: 08/11/2024]
Abstract
Phosphoryl transfer is a fundamental reaction in cellular signaling and metabolism that requires Mg2+ as an essential cofactor. While the primary function of Mg2+ is electrostatic activation of substrates, such as ATP, the full spectrum of catalytic mechanisms exerted by Mg2+ is not known. In this study, we integrate structural biology methods, molecular dynamic (MD) simulations, phylogeny, and enzymology assays to provide molecular insights into Mg2+-dependent structural reorganization in the active site of the metabolic enzyme adenylate kinase. Our results demonstrate that Mg2+ induces a conformational rearrangement of the substrates (ATP and ADP), resulting in a 30° adjustment of the angle essential for reversible phosphoryl transfer, thereby optimizing it for catalysis. MD simulations revealed transitions between conformational substates that link the fluctuation of the angle to large-scale enzyme dynamics. The findings contribute detailed insight into Mg2+ activation of enzymes and may be relevant for reversible and irreversible phosphoryl transfer reactions.
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Affiliation(s)
- Kwangho Nam
- Department of Chemistry and Biochemistry, University of Texas at Arlington, Arlington, TX 76019, USA
| | | | - Sonja Tischlik
- Department of Chemistry, Konstanz Research School Chemical Biology, University of Konstanz, 78464 Konstanz, Germany
| | - Chanrith Phoeurk
- Department of Chemistry, Umeå University, 901 87 Umeå, Sweden
- Department of Bio-Engineering, Royal University of Phnom Penh, Phnom Penh, Cambodia
| | | | - Léon Schierholz
- Department of Chemistry, Umeå University, 901 87 Umeå, Sweden
- Department of Molecular Biology, Umeå University, Umeå, 901 87, Sweden
| | - Jörgen Ådén
- Department of Chemistry, Umeå University, 901 87 Umeå, Sweden
| | - Per Rogne
- Department of Chemistry, Umeå University, 901 87 Umeå, Sweden
| | - Malte Drescher
- Department of Chemistry, Konstanz Research School Chemical Biology, University of Konstanz, 78464 Konstanz, Germany
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2
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Márquez-Moñino MÁ, Ortega-García R, Whitfield H, Riley AM, Infantes L, Garrett SW, Shipton ML, Brearley CA, Potter BVL, González B. Substrate promiscuity of inositol 1,4,5-trisphosphate kinase driven by structurally-modified ligands and active site plasticity. Nat Commun 2024; 15:1502. [PMID: 38374076 PMCID: PMC10876669 DOI: 10.1038/s41467-024-45917-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Accepted: 02/05/2024] [Indexed: 02/21/2024] Open
Abstract
D-myo-inositol 1,4,5-trisphosphate (InsP3) is a fundamental second messenger in cellular Ca2+ mobilization. InsP3 3-kinase, a highly specific enzyme binding InsP3 in just one mode, phosphorylates InsP3 specifically at its secondary 3-hydroxyl group to generate a tetrakisphosphate. Using a chemical biology approach with both synthetised and established ligands, combining synthesis, crystallography, computational docking, HPLC and fluorescence polarization binding assays using fluorescently-tagged InsP3, we have surveyed the limits of InsP3 3-kinase ligand specificity and uncovered surprisingly unforeseen biosynthetic capacity. Structurally-modified ligands exploit active site plasticity generating a helix-tilt. These facilitated uncovering of unexpected substrates phosphorylated at a surrogate extended primary hydroxyl at the inositol pseudo 3-position, applicable even to carbohydrate-based substrates. Crystallization experiments designed to allow reactions to proceed in situ facilitated unequivocal characterization of the atypical tetrakisphosphate products. In summary, we define features of InsP3 3-kinase plasticity and substrate tolerance that may be more widely exploitable.
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Affiliation(s)
- María Ángeles Márquez-Moñino
- Department of Crystallography and Structural Biology, Institute of Physical-Chemistry Blas Cabrera, CSIC, Serrano 119, 28006, Madrid, Spain
| | - Raquel Ortega-García
- Department of Crystallography and Structural Biology, Institute of Physical-Chemistry Blas Cabrera, CSIC, Serrano 119, 28006, Madrid, Spain
| | - Hayley Whitfield
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Andrew M Riley
- Drug Discovery and Medicinal Chemistry, Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK
| | - Lourdes Infantes
- Department of Crystallography and Structural Biology, Institute of Physical-Chemistry Blas Cabrera, CSIC, Serrano 119, 28006, Madrid, Spain
| | - Shane W Garrett
- Wolfson Laboratory of Medicinal Chemistry, Department of Life Sciences, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Megan L Shipton
- Drug Discovery and Medicinal Chemistry, Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK
| | - Charles A Brearley
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Barry V L Potter
- Drug Discovery and Medicinal Chemistry, Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK.
- Wolfson Laboratory of Medicinal Chemistry, Department of Life Sciences, University of Bath, Claverton Down, Bath, BA2 7AY, UK.
| | - Beatriz González
- Department of Crystallography and Structural Biology, Institute of Physical-Chemistry Blas Cabrera, CSIC, Serrano 119, 28006, Madrid, Spain.
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3
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Whitfield H, Rodriguez RF, Shipton ML, Li AW, Riley AM, Potter BV, Hemmings AM, Brearley CA. Crystal Structure and Enzymology of Solanum tuberosum Inositol Tris/Tetrakisphosphate Kinase 1 ( StITPK1). Biochemistry 2024; 63:42-52. [PMID: 38146842 PMCID: PMC10765375 DOI: 10.1021/acs.biochem.3c00404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Revised: 11/30/2023] [Accepted: 11/30/2023] [Indexed: 12/27/2023]
Abstract
Inositol phosphates and their pyrophosphorylated derivatives are responsive to the phosphate supply and are agents of phosphate homeostasis and other aspects of physiology. It seems likely that the enzymes that interconvert these signals work against the prevailing milieu of mixed populations of competing substrates and products. The synthesis of inositol pyrophosphates is mediated in plants by two classes of ATP-grasp fold kinase: PPIP5 kinases, known as VIH, and members of the inositol tris/tetrakisphosphate kinase (ITPK) family, specifically ITPK1/2. A molecular explanation of the contribution of ITPK1/2 to inositol pyrophosphate synthesis and turnover in plants is incomplete: the absence of nucleotide in published crystal structures limits the explanation of phosphotransfer reactions, and little is known of the affinity of potential substrates and competitors for ITPK1. Herein, we describe a complex of ADP and StITPK1 at 2.26 Å resolution and use a simple fluorescence polarization approach to compare the affinity of binding of diverse inositol phosphates, inositol pyrophosphates, and analogues. By simple HPLC, we reveal the novel catalytic capability of ITPK1 for different inositol pyrophosphates and show Ins(3,4,5,6)P4 to be a potent inhibitor of the inositol pyrophosphate-synthesizing activity of ITPK1. We further describe the exquisite specificity of ITPK1 for the myo-isomer among naturally occurring inositol hexakisphosphates.
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Affiliation(s)
- Hayley
L. Whitfield
- School
of Biological Sciences, University of East
Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K.
| | - Raquel Faba Rodriguez
- School
of Biological Sciences, University of East
Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K.
- School
of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K.
| | - Megan L. Shipton
- Medicinal
Chemistry & Drug Discovery, Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, U.K.
| | - Arthur W.H. Li
- School
of Biological Sciences, University of East
Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K.
- School
of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K.
| | - Andrew M. Riley
- Medicinal
Chemistry & Drug Discovery, Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, U.K.
| | - Barry V.L. Potter
- Medicinal
Chemistry & Drug Discovery, Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, U.K.
| | - Andrew M. Hemmings
- School
of Biological Sciences, University of East
Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K.
- School
of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K.
- College
of Food Science and Technology, Shanghai
Ocean University, Shanghai 201306, China
| | - Charles A. Brearley
- School
of Biological Sciences, University of East
Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K.
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4
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Benjamin B, Goldgur Y, Jork N, Jessen HJ, Schwer B, Shuman S. Structures of Fission Yeast Inositol Pyrophosphate Kinase Asp1 in Ligand-Free, Substrate-Bound, and Product-Bound States. mBio 2022; 13:e0308722. [PMID: 36468882 PMCID: PMC9765450 DOI: 10.1128/mbio.03087-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 11/07/2022] [Indexed: 12/12/2022] Open
Abstract
Expression of the fission yeast Schizosaccharomyces pombe phosphate regulon is sensitive to the intracellular level of the inositol pyrophosphate signaling molecule 1,5-IP8. IP8 dynamics are determined by Asp1, a bifunctional enzyme consisting of an N-terminal kinase domain and a C-terminal pyrophosphatase domain that catalyze IP8 synthesis and catabolism, respectively. Here, we report structures of the Asp1 kinase domain, crystallized with two protomers in the asymmetric unit, one of which was complexed with ligands (ADPNP, ADP, or ATP; Mg2+ or Mn2+; IP6, 5-IP7, or 1,5-IP8) and the other which was ligand-free. The ligand-free enzyme adopts an "open" conformation that allows ingress of substrates and egress of products. ADPNP, ADP, and ATP and associated metal ions occupy a deep phospho-donor pocket in the active site. IP6 or 5-IP7 engagement above the nucleotide favors adoption of a "closed" conformation, in which surface protein segments undergo movement and a disordered-to-ordered transition to form an inositol polyphosphate-binding site. In a structure mimetic of the kinase Michaelis complex, the anionic 5-IP7 phosphates are encaged by an ensemble of nine cationic amino acids: Lys43, Arg223, Lys224, Lys260, Arg274, Arg285, Lys290, Arg293, and Lys341. Alanine mutagenesis of amino acids that contact the adenosine nucleoside of the ATP donor underscored the contributions of Asp258 interaction with the ribose 3'-OH and of Glu248 with adenine-N6. Changing Glu248 to Gln elicited a gain of function whereby the kinase became adept at using GTP as phosphate donor. Wild-type Asp1 kinase can utilize N6-benzyl-ATP as phosphate donor. IMPORTANCE The inositol pyrophosphate signaling molecule 1,5-IP8 modulates fission yeast phosphate homeostasis via its action as an agonist of RNA 3'-processing and transcription termination. Cellular IP8 levels are determined by Asp1, a bifunctional enzyme composed of an N-terminal kinase and a C-terminal pyrophosphatase domain. Here, we present a series of crystal structures of the Asp1 kinase domain, in a ligand-free state and in complexes with nucleotides ADPNP, ADP, and ATP, divalent cations magnesium and manganese, and inositol polyphosphates IP6, 5-IP7, and 1,5-IP8. Substrate binding elicits a switch from open to closed conformations, entailing a disordered-to-ordered transition and a rearrangement or movement of two peptide segments that form a binding site for the phospho-acceptor. Our structures, along with structure-guided mutagenesis, fortify understanding of the mechanism and substrate specificity of Asp1 kinase, and they extend and complement structural and functional studies of the orthologous human kinase PPIP5K2.
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Affiliation(s)
- Bradley Benjamin
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York, USA
- Gerstner Sloan Kettering Graduate School of Biomedical Sciences, New York, New York, USA
| | - Yehuda Goldgur
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York, USA
| | - Nikolaus Jork
- Institute of Organic Chemistry, University of Freiburg, Freiburg, Germany
| | - Henning J. Jessen
- Institute of Organic Chemistry, University of Freiburg, Freiburg, Germany
| | - Beate Schwer
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York, USA
| | - Stewart Shuman
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York, USA
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5
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Zong G, Shears SB, Wang H. Structural and catalytic analyses of the InsP 6 kinase activities of higher plant ITPKs. FASEB J 2022; 36:e22380. [PMID: 35635723 PMCID: PMC9202514 DOI: 10.1096/fj.202200393r] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 05/04/2022] [Accepted: 05/16/2022] [Indexed: 09/21/2023]
Abstract
Inositol phosphate signaling in plants is of substantial agricultural interest, with a considerable focus on the inositol tris/tetrakisphosphate kinase (ITPK) family of inositol phosphate kinases. Historically, the 4-6 isoforms of ITPKs that higher plants each express have been studied for their multiplexing a metabolic pathway to synthesize inositol hexakisphosphate (ie InsP6 or phytate), through the phosphorylation and dephosphorylation of multiple inositol phosphates, including Ins(1,3,4,5,6)P5 (inositol-1,3,4,5,6-pentakisphosphate). A more recent discovery is ITPK-catalyzed phosphorylation of InsP6 to inositol pyrophosphates, which regulate plant immunity and phosphate homeostasis. However, a molecular-based explanation for these alternate catalytic activities has been missing, because no plant ITPK structure has previously been solved. Herein, we provide biochemical and structural analyses of ITPKs from Zea mays and Glycine max. For this work we introduce a simple, enzyme-coupled microplate-based assay of InsP6 kinase activity that should promote more general access to this important field. Furthermore, a ZmITPK1/InsP6 crystal complex is described at a resolution of 2.6 Å, which identifies a number of catalytically important residues; their functionality is confirmed by mutagenesis. We further demonstrate that ZmITPK1 adds a β-phosphate to the 3-position of Ins(1,2,3,4,5)P5 , yielding a candidate signal for regulating phosphate homeostasis. An impactful discovery is our description of a 29-residue catalytic specificity element; by interchanging this element between GmITPK1 and GmITPK2, we demonstrate how its isoform-specific sequence specifically determines whether the host protein phosphorylates InsP6 , without substantially affecting Ins(1,3,4,5,6)P5 metabolism. Our structural rationalization of key catalytic differences between alternate ITPK isoforms will complement future research into their functional diversity.
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Affiliation(s)
- Guangning Zong
- Inositol Signaling Section, Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709 USA
| | - Stephen B. Shears
- Inositol Signaling Section, Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709 USA
| | - Huanchen Wang
- Inositol Signaling Section, Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709 USA
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6
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Riemer E, Pullagurla NJ, Yadav R, Rana P, Jessen HJ, Kamleitner M, Schaaf G, Laha D. Regulation of plant biotic interactions and abiotic stress responses by inositol polyphosphates. FRONTIERS IN PLANT SCIENCE 2022; 13:944515. [PMID: 36035672 PMCID: PMC9403785 DOI: 10.3389/fpls.2022.944515] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2022] [Accepted: 07/20/2022] [Indexed: 05/14/2023]
Abstract
Inositol pyrophosphates (PP-InsPs), derivatives of inositol hexakisphosphate (phytic acid, InsP6) or lower inositol polyphosphates, are energy-rich signaling molecules that have critical regulatory functions in eukaryotes. In plants, the biosynthesis and the cellular targets of these messengers are not fully understood. This is because, in part, plants do not possess canonical InsP6 kinases and are able to synthesize PP-InsP isomers that appear to be absent in yeast or mammalian cells. This review will shed light on recent discoveries in the biosynthesis of these enigmatic messengers and on how they regulate important physiological processes in response to abiotic and biotic stresses in plants.
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Affiliation(s)
- Esther Riemer
- Departmentof Plant Nutrition, Institute of Crop Science and Resource Conservation, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
- *Correspondence: Esther Riemer,
| | | | - Ranjana Yadav
- Department of Biochemistry, Indian Institute of Science, Bengaluru, India
| | - Priyanshi Rana
- Department of Biochemistry, Indian Institute of Science, Bengaluru, India
| | - Henning J. Jessen
- Department of Chemistry and Pharmacy & CIBSS – The Center of Biological Signaling Studies, Albert-Ludwigs University Freiburg, Freiburg, Germany
| | - Marília Kamleitner
- Departmentof Plant Nutrition, Institute of Crop Science and Resource Conservation, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Gabriel Schaaf
- Departmentof Plant Nutrition, Institute of Crop Science and Resource Conservation, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Debabrata Laha
- Department of Biochemistry, Indian Institute of Science, Bengaluru, India
- Debabrata Laha,
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7
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Ricaña CL, Dick RA. Inositol Phosphates and Retroviral Assembly: A Cellular Perspective. Viruses 2021; 13:v13122516. [PMID: 34960784 PMCID: PMC8703376 DOI: 10.3390/v13122516] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 12/09/2021] [Accepted: 12/11/2021] [Indexed: 12/13/2022] Open
Abstract
Understanding the molecular mechanisms of retroviral assembly has been a decades-long endeavor. With the recent discovery of inositol hexakisphosphate (IP6) acting as an assembly co-factor for human immunodeficiency virus (HIV), great strides have been made in retroviral research. In this review, the enzymatic pathways to synthesize and metabolize inositol phosphates (IPs) relevant to retroviral assembly are discussed. The functions of these enzymes and IPs are outlined in the context of the cellular biology important for retroviruses. Lastly, the recent advances in understanding the role of IPs in retroviral biology are surveyed.
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8
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Kröber T, Bartsch SM, Fiedler D. Pharmacological tools to investigate inositol polyphosphate kinases - Enzymes of increasing therapeutic relevance. Adv Biol Regul 2021; 83:100836. [PMID: 34802993 DOI: 10.1016/j.jbior.2021.100836] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 10/27/2021] [Accepted: 10/28/2021] [Indexed: 01/01/2023]
Abstract
Inositol poly- and pyrophosphates (InsPs and PP-InsPs) are a group of central eukaryotic metabolites and signaling molecules. Due to the diverse cellular functions and widespread diseases InsPs and PP-InsPs are associated with, pharmacological targeting of the kinases involved in their biosynthesis has become a significant research interest in the last decade. In particular, the development of inhibitors for inositol hexakisphosphate kinases (IP6Ks) has leaped forward, while other inositol phosphate kinases have received scant attention. This review summarizes the efforts undertaken so far for discovering potent and selective inhibitors for this diverse group of small molecule kinases. The benefits of pharmacological inhibition are highlighted, given the multiple kinase-independent functions of inositol phosphate kinases. The distinct structural families of InsP and PP-InsP kinases are presented, and we discuss how compound availability for different inositol phosphate kinase families varies drastically. Lead compound discovery and optimization for the inositol kinases would benefit from detailed structural information on the ATP-binding sites of these kinases, as well as reliable biochemical and cellular read-outs to monitor inositol phosphate kinase activity in complex settings. Efforts to further tune well-established inhibitors, while simultaneously reviving tool compound development for the more neglected kinases from this family are indisputably worthwhile, considering the large potential therapeutic benefits.
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Affiliation(s)
- Tim Kröber
- Leibniz Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Straße 10, 13125, Berlin, Germany; Humboldt-Universität zu Berlin, Institut für Chemie, Brook-Taylor-Straße 2, 12489, Berlin, Germany.
| | - Simon M Bartsch
- Leibniz Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Straße 10, 13125, Berlin, Germany; Humboldt-Universität zu Berlin, Institut für Chemie, Brook-Taylor-Straße 2, 12489, Berlin, Germany.
| | - Dorothea Fiedler
- Leibniz Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Straße 10, 13125, Berlin, Germany; Humboldt-Universität zu Berlin, Institut für Chemie, Brook-Taylor-Straße 2, 12489, Berlin, Germany.
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9
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Riemer E, Qiu D, Laha D, Harmel RK, Gaugler P, Gaugler V, Frei M, Hajirezaei MR, Laha NP, Krusenbaum L, Schneider R, Saiardi A, Fiedler D, Jessen HJ, Schaaf G, Giehl RFH. ITPK1 is an InsP 6/ADP phosphotransferase that controls phosphate signaling in Arabidopsis. MOLECULAR PLANT 2021; 14:1864-1880. [PMID: 34274522 PMCID: PMC8573591 DOI: 10.1016/j.molp.2021.07.011] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 06/28/2021] [Accepted: 07/13/2021] [Indexed: 05/20/2023]
Abstract
In plants, phosphate (Pi) homeostasis is regulated by the interaction of PHR transcription factors with stand-alone SPX proteins, which act as sensors for inositol pyrophosphates. In this study, we combined different methods to obtain a comprehensive picture of how inositol (pyro)phosphate metabolism is regulated by Pi and dependent on the inositol phosphate kinase ITPK1. We found that inositol pyrophosphates are more responsive to Pi than lower inositol phosphates, a response conserved across kingdoms. Using the capillary electrophoresis electrospray ionization mass spectrometry (CE-ESI-MS) we could separate different InsP7 isomers in Arabidopsis and rice, and identify 4/6-InsP7 and a PP-InsP4 isomer hitherto not reported in plants. We found that the inositol pyrophosphates 1/3-InsP7, 5-InsP7, and InsP8 increase several fold in shoots after Pi resupply and that tissue-specific accumulation of inositol pyrophosphates relies on ITPK1 activities and MRP5-dependent InsP6 compartmentalization. Notably, ITPK1 is critical for Pi-dependent 5-InsP7 and InsP8 synthesis in planta and its activity regulates Pi starvation responses in a PHR-dependent manner. Furthermore, we demonstrated that ITPK1-mediated conversion of InsP6 to 5-InsP7 requires high ATP concentrations and that Arabidopsis ITPK1 has an ADP phosphotransferase activity to dephosphorylate specifically 5-InsP7 under low ATP. Collectively, our study provides new insights into Pi-dependent changes in nutritional and energetic states with the synthesis of regulatory inositol pyrophosphates.
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Affiliation(s)
- Esther Riemer
- Department of Plant Nutrition, Institute of Crop Science and Resource Conservation, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany
| | - Danye Qiu
- Department of Chemistry and Pharmacy and CIBSS-Centre for Integrative Biological Signalling Studies, Albert-Ludwigs University Freiburg, 79104 Freiburg, Germany
| | - Debabrata Laha
- Medical Research Council Laboratory for Molecular Cell Biology (MRC-LMCB), University College London, London WC1E 6BT, UK; Department of Biochemistry, Indian Institute of Science, Bengaluru, Karnataka 560 012, India
| | - Robert K Harmel
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, 13125 Berlin, Germany; Department of Chemistry, Humboldt Universität zu Berlin, 12489 Berlin, Germany
| | - Philipp Gaugler
- Department of Plant Nutrition, Institute of Crop Science and Resource Conservation, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany
| | - Verena Gaugler
- Department of Plant Nutrition, Institute of Crop Science and Resource Conservation, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany
| | - Michael Frei
- Institute of Agronomy and Crop Physiology, Justus-Liebig University Giessen, 35392 Giessen, Germany
| | - Mohammad-Reza Hajirezaei
- Department of Physiology & Cell Biology, Leibniz-Institute of Plant Genetics and Crop Plant Research, 06466 Gatersleben, Germany
| | - Nargis Parvin Laha
- Department of Plant Nutrition, Institute of Crop Science and Resource Conservation, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany
| | - Lukas Krusenbaum
- Department of Plant Nutrition, Institute of Crop Science and Resource Conservation, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany
| | - Robin Schneider
- Department of Plant Nutrition, Institute of Crop Science and Resource Conservation, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany
| | - Adolfo Saiardi
- Medical Research Council Laboratory for Molecular Cell Biology (MRC-LMCB), University College London, London WC1E 6BT, UK
| | - Dorothea Fiedler
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, 13125 Berlin, Germany; Department of Chemistry, Humboldt Universität zu Berlin, 12489 Berlin, Germany
| | - Henning J Jessen
- Department of Chemistry and Pharmacy and CIBSS-Centre for Integrative Biological Signalling Studies, Albert-Ludwigs University Freiburg, 79104 Freiburg, Germany
| | - Gabriel Schaaf
- Department of Plant Nutrition, Institute of Crop Science and Resource Conservation, Rheinische Friedrich-Wilhelms-Universität Bonn, 53115 Bonn, Germany.
| | - Ricardo F H Giehl
- Department of Physiology & Cell Biology, Leibniz-Institute of Plant Genetics and Crop Plant Research, 06466 Gatersleben, Germany.
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10
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An ATP-responsive metabolic cassette comprised of inositol tris/tetrakisphosphate kinase 1 (ITPK1) and inositol pentakisphosphate 2-kinase (IPK1) buffers diphosphosphoinositol phosphate levels. Biochem J 2021; 477:2621-2638. [PMID: 32706850 PMCID: PMC7115839 DOI: 10.1042/bcj20200423] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 06/29/2020] [Accepted: 07/06/2020] [Indexed: 12/27/2022]
Abstract
Inositol polyphosphates are ubiquitous molecular signals in metazoans, as are their pyrophosphorylated derivatives that bear a so-called ‘high-energy’ phosphoanhydride bond. A structural rationale is provided for the ability of Arabidopsis inositol tris/tetrakisphosphate kinase 1 to discriminate between symmetric and enantiomeric substrates in the production of diverse symmetric and asymmetric myo-inositol phosphate and diphospho-myo-inositol phosphate (inositol pyrophosphate) products. Simple tools are applied to chromatographic resolution and detection of known and novel diphosphoinositol phosphates without resort to radiolabeling approaches. It is shown that inositol tris/tetrakisphosphate kinase 1 and inositol pentakisphosphate 2-kinase comprise a reversible metabolic cassette converting Ins(3,4,5,6)P4 into 5-InsP7 and back in a nucleotide-dependent manner. Thus, inositol tris/tetrakisphosphate kinase 1 is a nexus of bioenergetics status and inositol polyphosphate/diphosphoinositol phosphate metabolism. As such, it commands a role in plants that evolution has assigned to a different class of enzyme in mammalian cells. The findings and the methods described will enable a full appraisal of the role of diphosphoinositol phosphates in plants and particularly the relative contribution of reversible inositol phosphate hydroxykinase and inositol phosphate phosphokinase activities to plant physiology.
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11
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Laha D, Portela-Torres P, Desfougères Y, Saiardi A. Inositol phosphate kinases in the eukaryote landscape. Adv Biol Regul 2020; 79:100782. [PMID: 33422459 PMCID: PMC8024741 DOI: 10.1016/j.jbior.2020.100782] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 12/15/2020] [Accepted: 12/21/2020] [Indexed: 01/01/2023]
Abstract
Inositol phosphate encompasses a large multifaceted family of signalling molecules that originate from the combinatorial attachment of phosphate groups to the inositol ring. To date, four distinct inositol kinases have been identified, namely, IPK, ITPK, IPPK (IP5-2K), and PPIP5K. Although, ITPKs have recently been identified in archaea, eukaryotes have taken advantage of these enzymes to create a sophisticated signalling network based on inositol phosphates. However, it remains largely elusive what fundamental biochemical principles control the signalling cascade. Here, we present an evolutionary approach to understand the development of the 'inositol phosphate code' in eukaryotes. Distribution analyses of these four inositol kinase groups throughout the eukaryotic landscape reveal the loss of either ITPK, or of PPIP5K proteins in several species. Surprisingly, the loss of IPPK, an enzyme thought to catalyse the rate limiting step of IP6 (phytic acid) synthesis, was also recorded. Furthermore, this study highlights a noteworthy difference between animal (metazoan) and plant (archaeplastida) lineages. While metazoan appears to have a substantial amplification of IPK enzymes, archaeplastida genomes show a considerable increase in ITPK members. Differential evolution of IPK and ITPK between plant and animal lineage is likely reflective of converging functional adaptation of these two types of inositol kinases. Since, the IPK family comprises three sub-types IPMK, IP6K, and IP3-3K each with dedicated enzymatic specificity in metazoan, we propose that the amplified ITPK group in plant could be classified in sub-types with distinct enzymology.
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Affiliation(s)
- Debabrata Laha
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, WC1E6BT, London, UK
| | - Paloma Portela-Torres
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, WC1E6BT, London, UK
| | - Yann Desfougères
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, WC1E6BT, London, UK
| | - Adolfo Saiardi
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, WC1E6BT, London, UK.
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12
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ITPK1 mediates the lipid-independent synthesis of inositol phosphates controlled by metabolism. Proc Natl Acad Sci U S A 2019; 116:24551-24561. [PMID: 31754032 PMCID: PMC6900528 DOI: 10.1073/pnas.1911431116] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Inositol phosphates (IPs) are a class of signaling molecules regulating cell physiology. The best-characterized IP, the calcium release factor IP3, is generated by phospholipase C hydrolysis of phosphoinositides lipids. For historical and technical reasons, IPs synthesis is believed to originate from the lipid-generated IP3. While this is true in yeast, our work has demonstrated that other organisms use a “soluble” (nonlipid) route to synthesize IPs. This soluble pathway depends on the metabolic status of the cells, and is under the control of the kinase ITPK1, which phosphorylates inositol monophosphate likely generated from glucose. The data shed light on the evolutionary origin of IPs, signaling and tightening the link between these small molecules and basic metabolism. Inositol phosphates (IPs) comprise a network of phosphorylated molecules that play multiple signaling roles in eukaryotes. IPs synthesis is believed to originate with IP3 generated from PIP2 by phospholipase C (PLC). Here, we report that in mammalian cells PLC-generated IPs are rapidly recycled to inositol, and uncover the enzymology behind an alternative “soluble” route to synthesis of IPs. Inositol tetrakisphosphate 1-kinase 1 (ITPK1)—found in Asgard archaea, social amoeba, plants, and animals—phosphorylates I(3)P1 originating from glucose-6-phosphate, and I(1)P1 generated from sphingolipids, to enable synthesis of IP6. We also found using PAGE mass assay that metabolic blockage by phosphate starvation surprisingly increased IP6 levels in a ITPK1-dependent manner, establishing a route to IP6 controlled by cellular metabolic status, that is not detectable by traditional [3H]-inositol labeling. The presence of ITPK1 in archaeal clades thought to define eukaryogenesis indicates that IPs had functional roles before the appearance of the eukaryote.
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McNamara DE, Dovey CM, Hale AT, Quarato G, Grace CR, Guibao CD, Diep J, Nourse A, Cai CR, Wu H, Kalathur RC, Green DR, York JD, Carette JE, Moldoveanu T. Direct Activation of Human MLKL by a Select Repertoire of Inositol Phosphate Metabolites. Cell Chem Biol 2019; 26:863-877.e7. [PMID: 31031142 DOI: 10.1016/j.chembiol.2019.03.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 02/08/2019] [Accepted: 03/15/2019] [Indexed: 12/29/2022]
Abstract
Necroptosis is an inflammatory form of programmed cell death executed through plasma membrane rupture by the pseudokinase mixed lineage kinase domain-like (MLKL). We previously showed that MLKL activation requires metabolites of the inositol phosphate (IP) pathway. Here we reveal that I(1,3,4,6)P4, I(1,3,4,5,6)P5, and IP6 promote membrane permeabilization by MLKL through directly binding the N-terminal executioner domain (NED) and dissociating its auto-inhibitory region. We show that IP6 and inositol pentakisphosphate 2-kinase (IPPK) are required for necroptosis as IPPK deletion ablated IP6 production and inhibited necroptosis. The NED auto-inhibitory region is more extensive than originally described and single amino acid substitutions along this region induce spontaneous necroptosis by MLKL. Activating IPs bind three sites with affinity of 100-600 μM to destabilize contacts between the auto-inhibitory region and NED, thereby promoting MLKL activation. We therefore uncover MLKL's activating switch in NED triggered by a select repertoire of IP metabolites.
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Affiliation(s)
- Dan E McNamara
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Cole M Dovey
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Andrew T Hale
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Giovanni Quarato
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Christy R Grace
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Cristina D Guibao
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Jonathan Diep
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Amanda Nourse
- Molecular Interaction Analysis Shared Resource, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Casey R Cai
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Hong Wu
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Ravi C Kalathur
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Douglas R Green
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - John D York
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Jan E Carette
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - Tudor Moldoveanu
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
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14
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Dovey CM, Diep J, Clarke BP, Hale AT, McNamara DE, Guo H, Brown NW, Cao JY, Grace CR, Gough PJ, Bertin J, Dixon SJ, Fiedler D, Mocarski ES, Kaiser WJ, Moldoveanu T, York JD, Carette JE. MLKL Requires the Inositol Phosphate Code to Execute Necroptosis. Mol Cell 2018; 70:936-948.e7. [PMID: 29883610 PMCID: PMC5994928 DOI: 10.1016/j.molcel.2018.05.010] [Citation(s) in RCA: 102] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 02/12/2018] [Accepted: 05/07/2018] [Indexed: 01/28/2023]
Abstract
Necroptosis is an important form of lytic cell death triggered by injury and infection, but whether mixed lineage kinase domain-like (MLKL) is sufficient to execute this pathway is unknown. In a genetic selection for human cell mutants defective for MLKL-dependent necroptosis, we identified mutations in IPMK and ITPK1, which encode inositol phosphate (IP) kinases that regulate the IP code of soluble molecules. We show that IP kinases are essential for necroptosis triggered by death receptor activation, herpesvirus infection, or a pro-necrotic MLKL mutant. In IP kinase mutant cells, MLKL failed to oligomerize and localize to membranes despite proper receptor-interacting protein kinase-3 (RIPK3)-dependent phosphorylation. We demonstrate that necroptosis requires IP-specific kinase activity and that a highly phosphorylated product, but not a lowly phosphorylated precursor, potently displaces the MLKL auto-inhibitory brace region. These observations reveal control of MLKL-mediated necroptosis by a metabolite and identify a key molecular mechanism underlying regulated cell death.
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Affiliation(s)
- Cole M Dovey
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Jonathan Diep
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Bradley P Clarke
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Andrew T Hale
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Dan E McNamara
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Hongyan Guo
- Department of Microbiology, Immunology and Molecular Genetics, University of Texas Health Sciences Center, San Antonio, TX 78229, USA
| | - Nathaniel W Brown
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA; Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125 Berlin, Germany
| | | | - Christy R Grace
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Peter J Gough
- Host Defense Discovery Performance Unit, Infectious Diseases Therapy Area Unit, GlaxoSmithKline, Collegeville, PA 19426, USA
| | - John Bertin
- Pattern Recognition Receptor Discovery Performance Unit, Immuno-Inflammation Therapeutic Area, GlaxoSmithKline, Collegeville, PA 19426, USA
| | - Scott J Dixon
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Dorothea Fiedler
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125 Berlin, Germany
| | - Edward S Mocarski
- Department of Microbiology and Immunology, Emory Vaccine Center, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - William J Kaiser
- Department of Microbiology, Immunology and Molecular Genetics, University of Texas Health Sciences Center, San Antonio, TX 78229, USA
| | - Tudor Moldoveanu
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - John D York
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Jan E Carette
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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15
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Characterization and molecular modeling of Inositol 1,3,4 tris phosphate 5/6 kinase-2 from Glycine max (L) Merr.: comprehending its evolutionary conservancy at functional level. 3 Biotech 2018; 8:50. [PMID: 29354361 DOI: 10.1007/s13205-017-1076-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 12/26/2017] [Indexed: 01/20/2023] Open
Abstract
Soybean genome encodes a family of four inositol 1,3,4 trisphosphate 5/6 kinases which belong to the ATP-GRASP group of proteins. Inositol 1,3,4 trisphosphate kinase-2 (GmItpk2), catalyzing the ATP-dependent phosphorylation of Inositol 1,3,4 trisphosphate (IP3) to Inositol 1,3,4,5 tetra phosphate or Inositol 1,3,4,6 tetra phosphate, is a key enzyme diverting the flux of inositol phosphate pool towards phytate biosynthesis. Although considerable research on characterizing genes involved in phytate biosynthesis is accomplished at genomic and transcript level, characterization of the proteins is yet to be explored. In the present study, we report the isolation and expression of single copy Itpk2 (948 bp) from Glycine max cv Pusa-16 predicted to encode 315 amino acid protein with an isoelectric point of 5.9. Sequence analysis revealed that GmITPK2 shared highest similarity (80%) with Phaseolus vulgaris. The predicted 3D model confirmed 12 α helices and 14 β barrel sheets with ATP-binding site close to β sheet present towards the C-terminus of the protein molecule. Spatio-temporal transcript profiling signified GmItpk2 to be seed specific, with higher transcript levels in the early stage of seed development. The present study using various molecular and bio-computational tools could, therefore, help in improving our understanding of this key enzyme and prove to be a potential target towards generating low phytate trait in nutritionally rich crop like soybean.
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16
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Saiardi A, Azevedo C, Desfougères Y, Portela-Torres P, Wilson MSC. Microbial inositol polyphosphate metabolic pathway as drug development target. Adv Biol Regul 2017; 67:74-83. [PMID: 28964726 DOI: 10.1016/j.jbior.2017.09.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 09/20/2017] [Accepted: 09/21/2017] [Indexed: 12/27/2022]
Abstract
Inositol polyphosphates are a diverse and multifaceted class of intracellular messengers omnipresent in eukaryotic cells. These water-soluble molecules regulate many aspects of fundamental cell physiology. Removing this metabolic pathway is deleterious: inositol phosphate kinase null mutations can result in lethality or substantial growth phenotypes. Inositol polyphosphate synthesis occurs through the actions of a set of kinases that phosphorylate phospholipase-generated IP3 to higher phosphorylated forms, such as the fully phosphorylated IP6 and the inositol pyrophosphates IP7 and IP8. Unicellular organisms have a reduced array of the kinases for synthesis of higher phosphorylated inositol polyphosphates, while human cells possess two metabolic routes to IP6. The enzymes responsible for inositol polyphosphate synthesis have been identified in all eukaryote genomes, although their amino acid sequence homology is often barely detectable by common search algorithms. Homology between human and microbial inositol phosphate kinases is restricted to a few catalytically important residues. Recent studies of the inositol phosphate metabolic pathways in pathogenic fungi (Cryptococcus neoformans) and protozoa (Trypanosome brucei) have revealed the importance of the highly phosphorylated inositol polyphosphates to the fitness and thus virulence of these pathogens. Given this, identification of inositol kinase inhibitors specifically targeting the kinases of pathogenic microorganisms is desirable and achievable.
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Affiliation(s)
- Adolfo Saiardi
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK.
| | - Cristina Azevedo
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Yann Desfougères
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Paloma Portela-Torres
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Miranda S C Wilson
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
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17
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Wilson MSC, Saiardi A. Importance of Radioactive Labelling to Elucidate Inositol Polyphosphate Signalling. Top Curr Chem (Cham) 2017; 375:14. [PMID: 28101851 PMCID: PMC5396384 DOI: 10.1007/s41061-016-0099-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 12/21/2016] [Indexed: 01/09/2023]
Abstract
Inositol polyphosphates, in their water-soluble or lipid-bound forms, represent a large and multifaceted family of signalling molecules. Some inositol polyphosphates are well recognised as defining important signal transduction pathways, as in the case of the calcium release factor Ins(1,4,5)P3, generated by receptor activation-induced hydrolysis of the lipid PtdIns(4,5)P2 by phospholipase C. The birth of inositol polyphosphate research would not have occurred without the use of radioactive phosphate tracers that enabled the discovery of the “PI response”. Radioactive labels, mainly of phosphorus but also carbon and hydrogen (tritium), have been instrumental in the development of this research field and the establishment of the inositol polyphosphates as one of the most important networks of regulatory molecules present in eukaryotic cells. Advancements in microscopy and mass spectrometry and the development of colorimetric assays have facilitated inositol polyphosphate research, but have not eliminated the need for radioactive experimental approaches. In fact, such experiments have become easier with the cloning of the inositol polyphosphate kinases, enabling the systematic labelling of specific positions of the inositol ring with radioactive phosphate. This approach has been valuable for elucidating their metabolic pathways and identifying specific and novel functions for inositol polyphosphates. For example, the synthesis of radiolabelled inositol pyrophosphates has allowed the discovery of a new protein post-translational modification. Therefore, radioactive tracers have played and will continue to play an important role in dissecting the many complex aspects of inositol polyphosphate physiology. In this review we aim to highlight the historical importance of radioactivity in inositol polyphosphate research, as well as its modern usage.
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Affiliation(s)
- Miranda S C Wilson
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Adolfo Saiardi
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, Gower Street, London, WC1E 6BT, UK.
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18
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Li C, Lev S, Saiardi A, Desmarini D, Sorrell TC, Djordjevic JT. Inositol Polyphosphate Kinases, Fungal Virulence and Drug Discovery. J Fungi (Basel) 2016; 2:jof2030024. [PMID: 29376941 PMCID: PMC5753137 DOI: 10.3390/jof2030024] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 08/23/2016] [Accepted: 08/30/2016] [Indexed: 12/31/2022] Open
Abstract
Opportunistic fungi are a major cause of morbidity and mortality world-wide, particularly in immunocompromised individuals. Developing new treatments to combat invasive fungal disease is challenging given that fungal and mammalian host cells are eukaryotic, with similar organization and physiology. Even therapies targeting unique fungal cell features have limitations and drug resistance is emerging. New approaches to the development of antifungal drugs are therefore needed urgently. Cryptococcus neoformans, the commonest cause of fungal meningitis worldwide, is an accepted model for studying fungal pathogenicity and driving drug discovery. We recently characterized a phospholipase C (Plc1)-dependent pathway in C. neoformans comprising of sequentially-acting inositol polyphosphate kinases (IPK), which are involved in synthesizing inositol polyphosphates (IP). We also showed that the pathway is essential for fungal cellular function and pathogenicity. The IP products of the pathway are structurally diverse, each consisting of an inositol ring, with phosphate (P) and pyrophosphate (PP) groups covalently attached at different positions. This review focuses on (1) the characterization of the Plc1/IPK pathway in C. neoformans; (2) the identification of PP-IP₅ (IP₇) as the most crucial IP species for fungal fitness and virulence in a mouse model of fungal infection; and (3) why IPK enzymes represent suitable candidates for drug development.
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Affiliation(s)
- Cecilia Li
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, The University of Sydney, Westmead, NSW 2145, Australia.
| | - Sophie Lev
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, The University of Sydney, Westmead, NSW 2145, Australia.
| | - Adolfo Saiardi
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK.
| | - Desmarini Desmarini
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, The University of Sydney, Westmead, NSW 2145, Australia.
| | - Tania C Sorrell
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, The University of Sydney, Westmead, NSW 2145, Australia.
- Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Westmead, NSW 2145, Australia.
- Westmead Hospital, Westmead, NSW 2145, Australia.
| | - Julianne T Djordjevic
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, The University of Sydney, Westmead, NSW 2145, Australia.
- Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Westmead, NSW 2145, Australia.
- Westmead Hospital, Westmead, NSW 2145, Australia.
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19
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Abstract
Eukaryotic cells have ubiquitously utilized the myo-inositol backbone to generate a diverse array of signalling molecules. This is achieved by arranging phosphate groups around the six-carbon inositol ring. There is virtually no biological process that does not take advantage of the uniquely variable architecture of phosphorylated inositol. In inositol biology, phosphates are able to form three distinct covalent bonds: phosphoester, phosphodiester and phosphoanhydride bonds, with each providing different properties. The phosphoester bond links phosphate groups to the inositol ring, the variable arrangement of which forms the basis of the signalling capacity of the inositol phosphates. Phosphate groups can also form the structural bridge between myo-inositol and diacylglycerol through the phosphodiester bond. The resulting lipid-bound inositol phosphates, or phosphoinositides, further expand the signalling potential of this family of molecules. Finally, inositol is also notable for its ability to host more phosphates than it has carbons. These unusual organic molecules are commonly referred to as the inositol pyrophosphates (PP-IPs), due to the presence of high-energy phosphoanhydride bonds (pyro- or diphospho-). PP-IPs themselves constitute a varied family of molecules with one or more pyrophosphate moiety/ies located around the inositol. Considering the relationship between phosphate and inositol, it is no surprise that members of the inositol phosphate family also regulate cellular phosphate homoeostasis. Notably, the PP-IPs play a fundamental role in controlling the metabolism of the ancient polymeric form of phosphate, inorganic polyphosphate (polyP). Here we explore the intimate links between phosphate, inositol phosphates and polyP, speculating on the evolution of these relationships.
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20
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Cdc123, a Cell Cycle Regulator Needed for eIF2 Assembly, Is an ATP-Grasp Protein with Unique Features. Structure 2015. [PMID: 26211610 DOI: 10.1016/j.str.2015.06.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Eukaryotic initiation factor 2 (eIF2), a heterotrimeric guanosine triphosphatase, has a central role in protein biosynthesis by supplying methionylated initiator tRNA to the ribosomal translation initiation complex and by serving as a target for translational control in response to stress. Recent work identified a novel step indispensable for eIF2 function: assembly of eIF2 from its three subunits by the cell proliferation protein Cdc123. We report the first crystal structure of a Cdc123 representative, that from Schizosaccharomyces pombe, both isolated and bound to domain III of Saccharomyces cerevisiae eIF2γ. The structures show that Cdc123 resembles enzymes of the ATP-grasp family. Indeed, Cdc123 binds ATP-Mg(2+), and conserved residues contacting ATP-Mg(2+) are essential for Cdc123 to support eIF2 assembly and cell viability. A docking of eIF2αγ onto Cdc123, combined with genetic and biochemical experiments, allows us to propose a model explaining how Cdc123 participates in the biogenesis of eIF2 through facilitating assembly of eIF2γ to eIF2α.
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21
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Cuchillo R, Pinto-Gil K, Michel J. A Collective Variable for the Rapid Exploration of Protein Druggability. J Chem Theory Comput 2015; 11:1292-307. [PMID: 26579775 DOI: 10.1021/ct501072t] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Rémi Cuchillo
- EaStCHEM School of Chemistry, Joseph Black Building, West Mains
Road, Edinburgh EH9 3JJ, United Kingdom
| | - Kevin Pinto-Gil
- EaStCHEM School of Chemistry, Joseph Black Building, West Mains
Road, Edinburgh EH9 3JJ, United Kingdom
| | - Julien Michel
- EaStCHEM School of Chemistry, Joseph Black Building, West Mains
Road, Edinburgh EH9 3JJ, United Kingdom
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22
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Ingle BL, Cundari TR. Impact of divalent metal cations on the catalysis of peptide bonds: a DFT study. J COORD CHEM 2014. [DOI: 10.1080/00958972.2014.964223] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Brandall L. Ingle
- Center for Advanced Scientific Computing and Modeling (CASCaM), Department of Chemistry, University of North Texas, Denton, TX, USA
| | - Thomas R. Cundari
- Center for Advanced Scientific Computing and Modeling (CASCaM), Department of Chemistry, University of North Texas, Denton, TX, USA
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23
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IP6K structure and the molecular determinants of catalytic specificity in an inositol phosphate kinase family. Nat Commun 2014; 5:4178. [PMID: 24956979 DOI: 10.1038/ncomms5178] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 05/21/2014] [Indexed: 01/27/2023] Open
Abstract
Inositol trisphosphate kinases (IP3Ks) and inositol hexakisphosphate kinases (IP6Ks) each regulate specialized signalling activities by phosphorylating either InsP3 or InsP6 respectively. The molecular basis for these different kinase activities can be illuminated by a structural description of IP6K. Here we describe the crystal structure of an Entamoeba histolytica hybrid IP6K/IP3K, an enzymatic parallel to a 'living fossil'. Through molecular modelling and mutagenesis, we extrapolated our findings to human IP6K2, which retains vestigial IP3K activity. Two structural elements, an α-helical pair and a rare, two-turn 310 helix, together forge a substrate-binding pocket with an open clamshell geometry. InsP6 forms substantial contacts with both structural elements. Relative to InsP6, enzyme-bound InsP3 rotates 55° closer to the α-helices, which provide most of the protein's interactions with InsP3. These data reveal the molecular determinants of IP6K activity, and suggest an unusual evolutionary trajectory for a primordial kinase that could have favored efficient bifunctionality, before propagation of separate IP3Ks and IP6Ks.
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Gosein V, Miller GJ. Conformational stability of inositol 1,3,4,5,6-pentakisphosphate 2-kinase (IPK1) dictates its substrate selectivity. J Biol Chem 2013; 288:36788-95. [PMID: 24165122 DOI: 10.1074/jbc.m113.512731] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Inositol 1,3,4,5,6-pentakisphosphate 2-kinase (IPK1) converts inositol 1,3,4,5,6-pentakisphosphate(IP5) to inositol hexakisphosphate (IP6). IPK1 shares structural similarity with protein kinases and is suspected to employ a similar mechanism of activation. Previous studies revealed roles for the 1- and 3-phosphates of IP5 in IPK1 activation and revealed that the N-lobe of IPK1 is unstable in the absence of inositol phosphate (IP). Here, we demonstrate the link between IPK1 substrate specificity and the stability of its N-lobe. Limited proteolysis of IPK1 revealed that N-lobe stability is dependent on the presence of the 1-phosphate of the substrate, whereas overall stability of IPK1 was increased in ternary complexes with nucleotide and IPs possessing 1- and 3-phosphates that engage the N-lobe of IPK1. Thus, the 1- and 3-phosphates possess dual roles in both IPK1 activation and IPK1 stability. To test whether kinase stability directly contributed to substrate selectivity of the kinase, we engineered IPK1 mutants with disulfide bonds that artificially stabilized the N-lobe in an IP-independent manner thereby mimicking its substrate-bound state in the absence of IP. IPK1 E82C/S142C exhibited a DTT-sensitive 5-fold increase in kcat for 3,4,5,6-inositol tetrakisphosphate (3,4,5,6-IP4) as compared with wild-type IPK1. The crystal structure of the IPK1 E82C/S142C mutant confirmed the presence of the disulfide bond and revealed a small shift in the N-lobe. Finally, we determined that IPK1 E82C/S142C is substantially more stable than wild-type IPK1 under nonreducing conditions, revealing that increased stability of IPK1 E82C/S142C correlates with changes in substrate specificity by allowing IPs lacking the stabilizing 1-phosphate to be used. Taken together, our results show that IPK1 substrate selection is linked to the ability of each potential substrate to stabilize IPK1.
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Affiliation(s)
- Varin Gosein
- From the Department of Pharmacology and Therapeutics, McGill University, Montréal, Quebec H3G 1Y6, Canada
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25
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Gosein V, Miller GJ. Roles of phosphate recognition in inositol 1,3,4,5,6-pentakisphosphate 2-kinase (IPK1) substrate binding and activation. J Biol Chem 2013; 288:26908-13. [PMID: 23884422 PMCID: PMC3772240 DOI: 10.1074/jbc.m113.487777] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Inositol phosphate kinases (IPKs) sequentially phosphorylate inositol phosphates (IPs) to yield a group of small signaling molecules involved in diverse cellular processes. IPK1 (inositol 1,3,4,5,6-pentakisphosphate 2-kinase) phosphorylates inositol 1,3,4,5,6-pentakisphosphate to inositol 1,2,3,4,5,6-hexakisphosphate; however, the mechanism of IP recognition employed by IPK1 is currently unresolved. We demonstrated previously that IPK1 possesses an unstable N-terminal lobe in the absence of IP, which led us to propose that the phosphate profile of the IP was linked to stabilization of IPK1. Here, we describe a systematic study to determine the roles of the 1-, 3-, 5-, and 6-phosphate groups of inositol 1,3,4,5,6-pentakisphosphate in IP binding and IPK1 activation. The 5- and 6-phosphate groups were the most important for IP binding to IPK1, and the 1- and 3-phosphate groups were more important for IPK1 activation than the others. Moreover, we demonstrate that there are three critical residues (Arg-130, Lys-170, and Lys-411) necessary for IPK1 activity. Arg-130 is the only substrate-binding N-terminal lobe residue that can render IPK1 inactive; its 1-phosphate is critical for full IPK1 activity and for stabilization of the active conformation of IPK1. Taken together, our results support the model for recognition of the IP substrate by IPK1 in which (i) the 4-, 5-, and 6-phosphates are initially recognized by the C-terminal lobe, and subsequently, (ii) the interaction between the 1-phosphate and Arg-130 stabilizes the N-terminal lobe and activates IPK1. This model of IP recognition, believed to be unique among IPKs, could be exploited for selective inhibition of IPK1 in future studies that investigate the role of higher IPs.
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Affiliation(s)
- Varin Gosein
- From the Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec H3G 1Y6, Canada
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26
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Tang Y, Tan S, Xue H. Arabidopsis inositol 1,3,4-trisphosphate 5/6 kinase 2 is required for seed coat development. Acta Biochim Biophys Sin (Shanghai) 2013; 45:549-60. [PMID: 23595027 DOI: 10.1093/abbs/gmt039] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Inositol 1,3,4-trisphosphate 5/6 kinase (ITPK) phosphorylates inositol 1,3,4-trisphosphate to form inositol 1,3,4,5-tetrakisphosphate and inositol 1,3,4,6-tetrakisphosphate which can be finally transferred to inositol hexaphosphate (IP₆) and play important roles during plant growth and development. There are 4 putative ITPK members in Arabidopsis. Expression pattern analysis showed that ITPK2 is constitutively expressed in various tissues. A T-DNA knockout mutant of ITPK2 was identified and scanning electron microscopy (SEM) analysis showed that the epidermis structure of seed coat was irregularly formed in seeds of itpk2-1 mutant, resulting in the increased permeability of seed coat to tetrazolium salts. Further analysis by gas chromatography coupled with mass spectrometry of lipid polyester monomers in cell wall confirmed a dramatic decrease in composition of suberin and cutin, which relate to the permeability of seed coat and the formation of which is accompanied with seed coat development. These results indicate that ITPK2 plays an essential role in seed coat development and lipid polyester barrier formation.
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Affiliation(s)
- Yong Tang
- National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
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Shears SB, Weaver JD, Wang H. Structural insight into inositol pyrophosphate turnover. Adv Biol Regul 2013; 53:19-27. [PMID: 23107997 PMCID: PMC3570603 DOI: 10.1016/j.jbior.2012.10.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 10/04/2012] [Indexed: 11/28/2022]
Abstract
The diphosphoinositol polyphosphates ("inositol pyrophosphates"; PP-InsPs) regulate many cellular processes in eukaryotes, including stress responses, apoptosis, vesicle trafficking, cytoskeletal dynamics, exocytosis, telomere maintenance, insulin signaling and neutrophil activation. Thus, the enzymes that control the metabolism of the PP-InsPs serve important cell signaling roles. In order to fully characterize how these enzymes are regulated, we need to determine the atomic-level architecture of their active sites. Only then can we fully appreciate reaction mechanisms and their modes of regulation. In this review, we summarize published information obtained from the structural analysis of a human diphosphoinositol polyphosphate phosphohydrolase (DIPP), and a human diphosphoinositol polyphosphate kinase (PPIP5K). This work includes the analysis of crystal complexes with substrates, products, transition state analogs, and a novel phosphonoacetate substrate analog.
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Affiliation(s)
- Stephen B Shears
- Inositol Signaling Group, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, PO Box 12233, NC 27709, USA.
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28
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Yates LA, Lumb CN, Brahme NN, Zalyte R, Bird LE, De Colibus L, Owens RJ, Calderwood DA, Sansom MSP, Gilbert RJC. Structural and functional characterization of the kindlin-1 pleckstrin homology domain. J Biol Chem 2012; 287:43246-61. [PMID: 23132860 PMCID: PMC3527912 DOI: 10.1074/jbc.m112.422089] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Revised: 10/21/2012] [Indexed: 11/06/2022] Open
Abstract
Inside-out activation of integrins is mediated via the binding of talin and kindlin to integrin β-subunit cytoplasmic tails. The kindlin FERM domain is interrupted by a pleckstrin homology (PH) domain within its F2 subdomain. Here, we present data confirming the importance of the kindlin-1 PH domain for integrin activation and its x-ray crystal structure at a resolution of 2.1 Å revealing a C-terminal second α-helix integral to the domain but found only in the kindlin protein family. An isoform-specific salt bridge occludes the canonical phosphoinositide binding site, but molecular dynamics simulations display transient switching to an alternative open conformer. Molecular docking reveals that the opening of the pocket would enable potential ligands to bind within it. Although lipid overlay assays suggested the PH domain binds inositol monophosphates, surface plasmon resonance demonstrated weak affinities for inositol 3,4,5-triphosphate (Ins(3,4,5)P(3); K(D) ∼100 μM) and no monophosphate binding. Removing the salt bridge by site-directed mutagenesis increases the PH domain affinity for Ins(3,4,5)P(3) as measured by surface plasmon resonance and enables it to bind PtdIns(3,5)P(2) on a dot-blot. Structural comparison with other PH domains suggests that the phosphate binding pocket in the kindlin-1 PH domain is more occluded than in kindlins-2 and -3 due to its salt bridge. In addition, the apparent affinity for Ins(3,4,5)P(3) is affected by the presence of PO(4) ions in the buffer. We suggest the physiological ligand of the kindlin-1 PH domain is most likely not an inositol phosphate but another phosphorylated species.
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Affiliation(s)
- Luke A. Yates
- From the Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, United Kingdom
| | - Craig N. Lumb
- the Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
| | - Nina N. Brahme
- the Department of Cell Biology and
- the Department of Pharmacology Yale University School of Medicine, New Haven, Connecticut 06520-8066, and
| | - Ruta Zalyte
- From the Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, United Kingdom
| | - Louise E. Bird
- From the Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, United Kingdom
- the Oxford Protein Production Facility United Kingdom, Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 0FA, United Kingdom
| | - Luigi De Colibus
- From the Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, United Kingdom
| | - Raymond J. Owens
- From the Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, United Kingdom
- the Oxford Protein Production Facility United Kingdom, Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 0FA, United Kingdom
| | - David A. Calderwood
- the Department of Cell Biology and
- the Department of Pharmacology Yale University School of Medicine, New Haven, Connecticut 06520-8066, and
| | - Mark S. P. Sansom
- the Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
| | - Robert J. C. Gilbert
- From the Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, United Kingdom
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Baños-Sanz JI, Sanz-Aparicio J, Whitfield H, Hamilton C, Brearley CA, González B. Conformational changes in inositol 1,3,4,5,6-pentakisphosphate 2-kinase upon substrate binding: role of N-terminal lobe and enantiomeric substrate preference. J Biol Chem 2012; 287:29237-49. [PMID: 22745128 DOI: 10.1074/jbc.m112.363671] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Inositol 1,3,4,5,6-pentakisphosphate 2-kinase (IP(5) 2-K) catalyzes the synthesis of inositol 1,2,3,4,5,6-hexakisphosphate from ATP and IP(5). Inositol 1,2,3,4,5,6-hexakisphosphate is implicated in crucial processes such as mRNA export, DNA editing, and phosphorus storage in plants. We previously solved the first structure of an IP(5) 2-K, which shed light on aspects of substrate recognition. However, failure of IP(5) 2-K to crystallize in the absence of inositide prompted us to study putative conformational changes upon substrate binding. We have made mutations to residues on a region of the protein that produces a clasp over the active site. A W129A mutant allowed us to capture IP(5) 2-K in its different conformations by crystallography. Thus, the IP(5) 2-K apo-form structure displays an open conformation, whereas the nucleotide-bound form shows a half-closed conformation, in contrast to the inositide-bound form obtained previously in a closed conformation. Both nucleotide and inositide binding produce large conformational changes that can be understood as two rigid domain movements, although local changes were also observed. Changes in intrinsic fluorescence upon nucleotide and inositide binding are in agreement with the crystallographic findings. Our work suggests that the clasp might be involved in enzyme kinetics, with the N-terminal lobe being essential for inositide binding and subsequent conformational changes. We also show how IP(5) 2-K discriminates between inositol 1,3,4,5-tetrakisphosphate and 3,4,5,6-tetrakisphosphate enantiomers and that substrate preference can be manipulated by Arg(130) mutation. Altogether, these results provide a framework for rational design of specific inhibitors with potential applications as biological tools for in vivo studies, which could assist in the identification of novel roles for IP(5) 2-K in mammals.
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Affiliation(s)
- José Ignacio Baños-Sanz
- Departamento de Cristalografía y Biología Estructural, Instituto de Química-Física Rocasolano, CSIC, Serrano 119, 28006-Madrid, Spain
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30
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Gosein V, Leung TF, Krajden O, Miller GJ. Inositol phosphate-induced stabilization of inositol 1,3,4,5,6-pentakisphosphate 2-kinase and its role in substrate specificity. Protein Sci 2012; 21:737-42. [PMID: 22362712 DOI: 10.1002/pro.2049] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Revised: 02/07/2012] [Accepted: 02/08/2012] [Indexed: 01/25/2023]
Abstract
Inositol phosphate kinases (IPKs) sequentially phosphorylate inositol phosphates (IPs) on their inositol rings to yield an array of signaling molecules. IPKs must possess the ability to recognize their physiological substrates from among a pool of over 30 cellular IPs that differ in numbers and positions of phosphates. Crystal structures from IPK subfamilies have revealed structural determinants for IP discrimination, which vary considerably between IPKs. However, recent structures of inositol 1,3,4,5,6-pentakisphosphate 2-kinase (IPK1) did not reveal how IPK1 selectively recognizes its physiological substrate, IP5, while excluding others. Here, we report that limited proteolysis has revealed the presence of multiple conformational states in the IPK1 catalytic cycle, with notable protection from protease only in the presence of IP. Further, a 3.1-Å crystal structure of IPK1 bound to ADP in the absence of IP revealed decreased order in residues 110-140 within the N-lobe of the kinase compared with structures in which IP is bound. Using this solution and crystallographic data, we propose a model for recognition of IP substrate by IPK1 wherein phosphate groups at the 4-, 5-, and 6-positions are recognized initially by the C-lobe with subsequent interaction of the 1-position phosphate by Arg130 that stabilizes this residue and the N-lobe. This model explains how IPK1 can be highly specific for a single IP substrate by linking its interactions with substrate phosphate groups to the stabilization of the N- and C-lobes and kinase activation.
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Affiliation(s)
- Varin Gosein
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada, H3G 1Y6
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31
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Regulation of inositol 1,3,4-trisphosphate 5/6-kinase (ITPK1) by reversible lysine acetylation. Proc Natl Acad Sci U S A 2012; 109:2290-5. [PMID: 22308441 DOI: 10.1073/pnas.1119740109] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The enzyme inositol 1,3,4-trisphosphate 5/6-kinase (ITPK1) catalyzes the rate-limiting step in the formation of higher phosphorylated forms of inositol in mammalian cells. Because it sits at a key regulatory point in the inositol metabolic pathway, its activity is likely to be regulated. We have previously shown that ITPK1 is phosphorylated, a posttranslational modification used by cells to regulate enzyme activity. We show here that ITPK1 is modified by acetylation of internal lysine residues. The acetylation sites, as determined by mass spectrometry, were found to be lysines 340, 383, and 410, which are all located on the surface of this protein. Overexpression of the acetyltransferases CREB-binding protein or p300 resulted in the acetylation of ITPK1, whereas overexpression of mammalian silent information regulator 2 resulted in the deacetylation of ITPK1. Functionally, ITPK1 acetylation regulates its stability. CREB-binding protein dramatically decreased the half-life of ITPK1. We further found that ITPK1 acetylation down-regulated its enzyme activity. HEK293 cells stably expressing acetylated ITPK1 had reduced levels of the higher phosphorylated forms of inositol, compared with the levels seen in cells expressing unacetylated ITPK1. These results demonstrate that lysine acetylation alters both the stability as well as the activity of ITPK1 in cells.
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32
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Shears SB, Ganapathi SB, Gokhale NA, Schenk TMH, Wang H, Weaver JD, Zaremba A, Zhou Y. Defining signal transduction by inositol phosphates. Subcell Biochem 2012; 59:389-412. [PMID: 22374098 PMCID: PMC3925325 DOI: 10.1007/978-94-007-3015-1_13] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Ins(1,4,5)P(3) is a classical intracellular messenger: stimulus-dependent changes in its levels elicits biological effects through its release of intracellular Ca(2+) stores. The Ins(1,4,5)P(3) response is "switched off" by its metabolism to a range of additional inositol phosphates. These metabolites have themselves come to be collectively described as a signaling "family". The validity of that latter definition is critically examined in this review. That is, we assess the strength of the hypothesis that Ins(1,4,5)P(3) metabolites are themselves "classical" signals. Put another way, what is the evidence that the biological function of a particular inositol phosphate depends upon stimulus dependent changes in its levels? In this assessment, examples of an inositol phosphate acting as a cofactor (i.e. its function is not stimulus-dependent) do not satisfy our signaling criteria. We conclude that Ins(3,4,5,6)P(4) is, to date, the only Ins(1,4,5)P(3) metabolite that has been validated to act as a second messenger.
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Key Words
- adenosine deaminase
- akt
- β-cells
- calcium
- camp
- camkii
- chloride channel
- clc3
- compartmentalization
- dna repair
- endosomes
- erk
- frizzled receptor
- gap1ip4bp
- mrna export
- ins(1,4,5)p3
- ins(1,4,5)p4 receptor
- ins(1,3,4)p3
- ins(1,3,4,5)p4
- ins(1,3,4,5)p4 receptor
- ins(1,4,5,6)p4
- ins(3,4,5,6)p4
- ins(1,3,4,5,6)p5
- insp6
- insulin
- ipmk
- ipk2
- ip5k
- itp
- itpk1
- itpkb
- lymphocytes
- ku
- neutrophils
- protein phosphatase
- ptdins(4,5)p2
- ptdins(3,4,5)p3
- ph domain
- pten
- rasa3
- transcription
- wnt ligand
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Affiliation(s)
- Stephen B Shears
- Inositol Signaling Section, Laboratory of Signal Transduction, NIEHS, NIH, DHHS, Research Triangle Park, 27709, NC, USA, USA,
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Du H, Liu L, You L, Yang M, He Y, Li X, Xiong L. Characterization of an inositol 1,3,4-trisphosphate 5/6-kinase gene that is essential for drought and salt stress responses in rice. PLANT MOLECULAR BIOLOGY 2011; 77:547-63. [PMID: 22038091 DOI: 10.1007/s11103-011-9830-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Accepted: 09/12/2011] [Indexed: 05/06/2023]
Abstract
Drought and salt stresses are major limiting factors for crop production. To identify critical genes for stress resistance in rice (Oryza sativa L.), we screened T-DNA mutants and identified a drought- and salt-hypersensitive mutant dsm3. The mutant phenotype was caused by a T-DNA insertion in a gene encoding a putative inositol 1,3,4-trisphosphate 5/6-kinase previously named OsITPK2 with unknown function. Under drought stress conditions, the mutant had significantly less accumulation of osmolytes such as proline and soluble sugar and showed significantly reduced root volume, spikelet fertility, biomass, and grain yield; however, malondialdehyde level was increased in the mutant. Interestingly, overexpression of DSM3 (OsITPK2) in rice resulted in drought- and salt-hypersensitive phenotypes and physiological changes similar to those in the mutant. Inositol trisphosphate (IP3) level was decreased in the overexpressors under normal condition and drought stress. A few genes related to osmotic adjustment and reactive oxygen species scavenging were down-regulated in the mutant and overexpression lines. The expression level of DSM3 promoter-driven β-glucuronidase (GUS) reporter gene in rice was induced by drought, salt and abscisic acid. Protoplast transient expression assay indicated that DSM3 is an endoplasmic reticulum protein. Sequence analysis revealed six putative ITPKs in rice. Transcript level analysis of OsITPK genes revealed that they had different tempo-spatial expression patterns, and the responses of DSM3 to abiotic stresses, including drought, salinity, cold, and high temperature, were distinct from the other five members in rice. These results together suggest that DSM3/OsITPK2 is an important member of the OsITPK family for stress responses, and an optimal expression level is essential for drought and salt tolerance in rice.
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Affiliation(s)
- Hao Du
- National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, 430070 Wuhan, China
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Fawaz MV, Topper M, Firestine SM. The ATP-grasp enzymes. Bioorg Chem 2011; 39:185-91. [PMID: 21920581 PMCID: PMC3243065 DOI: 10.1016/j.bioorg.2011.08.004] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Revised: 08/12/2011] [Accepted: 08/13/2011] [Indexed: 12/17/2022]
Abstract
The ATP-grasp enzymes consist of a superfamily of 21 proteins that contain an atypical ATP-binding site, called the ATP-grasp fold. The ATP-grasp fold is comprised of two α+β domains that "grasp" a molecule of ATP between them and members of the family typically have an overall structural design containing three common conserved focal domains. The founding members of the family consist of biotin carboxylase, d-ala-d-ala ligase and glutathione synthetase, all of which catalyze the ATP-assisted reaction of a carboxylic acid with a nucleophile via the formation of an acylphosphate intermediate. While most members of the superfamily follow this mechanistic pathway, studies have demonstrated that two enzymes catalyze only the phosphoryl transfer step and thus are kinases instead of ligases. Members of the ATP-grasp superfamily are found in several metabolic pathways including de novo purine biosynthesis, gluconeogenesis, and fatty acid synthesis. Given the critical nature of these enzymes, researchers have actively sought the development of potent inhibitors of several members of the superfamily as antibacterial and anti-obseity agents. In this review, we will discuss the structure, function, mechanism, and inhibition of the ATP-grasp enzymes.
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Affiliation(s)
| | | | - Steven M. Firestine
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI 48201
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35
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Wang H, Falck JR, Hall TMT, Shears SB. Structural basis for an inositol pyrophosphate kinase surmounting phosphate crowding. Nat Chem Biol 2011; 8:111-6. [PMID: 22119861 PMCID: PMC3923263 DOI: 10.1038/nchembio.733] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Accepted: 08/30/2011] [Indexed: 01/16/2023]
Abstract
Inositol pyrophosphates (such as IP7 and IP8) are multifunctional signaling molecules that regulate diverse cellular activities. Inositol pyrophosphates have 'high-energy' phosphoanhydride bonds, so their enzymatic synthesis requires that a substantial energy barrier to the transition state be overcome. Additionally, inositol pyrophosphate kinases can show stringent ligand specificity, despite the need to accommodate the steric bulk and intense electronegativity of nature's most concentrated three-dimensional array of phosphate groups. Here we examine how these catalytic challenges are met by describing the structure and reaction cycle of an inositol pyrophosphate kinase at the atomic level. We obtained crystal structures of the kinase domain of human PPIP5K2 complexed with nucleotide cofactors and either substrates, product or a MgF(3)(-) transition-state mimic. We describe the enzyme's conformational dynamics, its unprecedented topological presentation of nucleotide and inositol phosphate, and the charge balance that facilitates partly associative in-line phosphoryl transfer.
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Affiliation(s)
- Huanchen Wang
- Inositol Signaling Group, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, USA.
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36
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Abstract
Comparative analysis of the sequences of enzymes encoded in a variety of prokaryotic and eukaryotic genomes reveals convergence and divergence at several levels. Functional convergence can be inferred when structurally distinct and hence non-homologous enzymes show the ability to catalyze the same biochemical reaction. In contrast, as a result of functional diversification, many structurally similar enzyme molecules act on substantially distinct substrates and catalyze diverse biochemical reactions. Here, we present updates on the ATP-grasp, alkaline phosphatase, cupin, HD hydrolase, and N-terminal nucleophile (Ntn) hydrolase enzyme superfamilies and discuss the patterns of sequence and structural conservation and diversity within these superfamilies. Typically, enzymes within a superfamily possess common sequence motifs and key active site residues, as well as (predicted) reaction mechanisms. These observations suggest that the strained conformation (the entatic state) of the active site, which is responsible for the substrate binding and formation of the transition complex, tends to be conserved within enzyme superfamilies. The subsequent fate of the transition complex is not necessarily conserved and depends on the details of the structures of the enzyme and the substrate. This variability of reaction outcomes limits the ability of sequence analysis to predict the exact enzymatic activities of newly sequenced gene products. Nevertheless, sequence-based (super)family assignments and generic functional predictions, even if imprecise, provide valuable leads for experimental studies and remain the best approach to the functional annotation of uncharacterized proteins from new genomes.
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Affiliation(s)
- Michael Y Galperin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland 20894
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland 20894.
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Kitamura M, Nishimoto H, Aoki K, Tsukamoto M, Aoki S. Molecular recognition of inositol 1,4,5-trisphosphate and model compounds in aqueous solution by ditopic Zn(2+) complexes containing chiral linkers. Inorg Chem 2010; 49:5316-27. [PMID: 20420391 DOI: 10.1021/ic1004038] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report on molecular recognition of inositol 1,4,5-trisphosphate (Ins(1,4,5)P(3)), an important intracellular second messenger, and some related model compounds, cyclohexanediol bisphosphate derivatives (CDP(2)), by ditopic Zn(2+) complexes containing chiral linkers ((S,S)- and (R,R)-11) in aqueous solution at physiological pH. A crystal structure analysis of (S,S)-11 indicated that the distance between two Zn(2+) ions (6.8 A) is suitable for accommodating two phosphate groups at the 4- and 5-positions of Ins(1,4,5)P(3) and two phosphate groups of trans-1,2-CDP(2). (1)H NMR, (31)P NMR, potentiometric pH, and isothermal calorimetric titration data indicate that (S,S)-11 forms 1:1 complexes with (S,S)- and (R,R)-1,2-CDP(2) at pH 7.4 and 25 degrees C. The apparent 1:1 complexation constants (log K(app)) for (S,S)-11-(S,S)-1,2-CDP(2) and (S,S)-11-(R,R)-1,2-CDP(2) (K(app) = [(S,S)-11-1,2-CDP(2) complex]/[(S,S)-11][1,2-CDP(2)] (M(-1))) were determined to be 7.6 +/- 0.1 and 7.3 +/- 0.1, respectively, demonstrating that both enantiomers of 11 bind to chiral trans-1,2-CDP(2) to almost the same extent. The log K(app) value of 6.3 was obtained for a 1:1 complex of (S,S)-11 with cis-1,3-CDP(2), while a small amount of 2:1 (S,S)-11-cis-1,3-CDP(2) was detected, as evidenced by electrospray ionization mass spectrometry (ESI-MS). In contrast, 11 formed several complexes with trans-1,4-CDP(2). On the basis of isothermal titration calorimetry data for (S,S)- and (R,R)-11 with Ins(1,4,5)P(3), it was concluded that 11 forms a 2:1 complex with Ins(1,4,5)P(3), in which the first molecule of 11 binds to the 4- and 5-phosphates of Ins(1,4,5)P(3) and the second molecule of 11 binds to the 1- and 5-phosphates.
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Affiliation(s)
- Masanori Kitamura
- Faculty of Pharmaceutical Sciences, Tokyo University of Science,2641 Yamazaki, Noda 278-8510, Japan
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Inositol 1,3,4,5,6-pentakisphosphate 2-kinase is a distant IPK member with a singular inositide binding site for axial 2-OH recognition. Proc Natl Acad Sci U S A 2010; 107:9608-13. [PMID: 20453199 DOI: 10.1073/pnas.0912979107] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Inositol phosphates (InsPs) are signaling molecules with multiple roles in cells. In particular (InsP(6)) is involved in mRNA export and editing or chromatin remodeling among other events. InsP(6) accumulates as mixed salts (phytate) in storage tissues of plants and plays a key role in their physiology. Human diets that are exclusively grain-based provide an excess of InsP(6) that, through chelation of metal ions, may have a detrimental effect on human health. Ins(1,3,4,5,6)P(5) 2-kinase (InsP(5) 2-kinase or Ipk1) catalyses the synthesis of InsP(6) from InsP(5) and ATP, and is the only enzyme that transfers a phosphate group to the axial 2-OH of the myo-inositide. We present the first structure for an InsP(5) 2-kinase in complex with both substrates and products. This enzyme presents a singular structural region for inositide binding that encompasses almost half of the protein. The key residues in substrate binding are identified, with Asp368 being responsible for recognition of the axial 2-OH. This study sheds light on the unique molecular mechanism for the synthesis of the precursor of inositol pyrophosphates.
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Best MD, Zhang H, Prestwich GD. Inositol polyphosphates, diphosphoinositol polyphosphates and phosphatidylinositol polyphosphate lipids: Structure, synthesis, and development of probes for studying biological activity. Nat Prod Rep 2010; 27:1403-30. [DOI: 10.1039/b923844c] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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40
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Baños-Sanz JI, Villate M, Sanz-Aparicio J, Brearley CA, González B. Crystallization and preliminary X-ray diffraction analysis of inositol 1,3,4,5,6-pentakisphosphate kinase from Arabidopsis thaliana. Acta Crystallogr Sect F Struct Biol Cryst Commun 2010; 66:102-6. [PMID: 20057083 PMCID: PMC2805549 DOI: 10.1107/s1744309109051057] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2009] [Accepted: 11/26/2009] [Indexed: 11/10/2022]
Abstract
Inositol 1,3,4,5,6-pentakisphosphate kinase (IP(5) 2-K) is an enzyme involved in inositol metabolism that synthesizes IP(6) (inositol 1,2,3,4,5,6-hexakisphosphate) from inositol 1,3,4,5,6-pentakisphosphate (IP(5)) and ATP. IP(6) is the major phosphorus reserve in plants, while in mammals it is involved in multiple cellular events such as DNA editing and chromatin remodelling. In addition, IP(6) is the precursor of other highly phosphorylated inositols which also play highly relevant roles. IP(5) 2-K is the only enzyme that phosphorylates the 2-OH axial position of the inositide and understanding its molecular mechanism of substrate specificity is of great interest in cell biology. IP(5) 2-K from Arabidopsis thaliana has been expressed in Escherichia coli as two different fusion proteins and purified. Both protein preparations yielded crystals of different quality, always in the presence of IP(6). The best crystals obtained for X-ray crystallographic analysis belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 58.124, b = 113.591, c = 142.478 A. Several diffraction data sets were collected for the native enzyme and two heavy-atom derivatives using a synchrotron source.
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Affiliation(s)
- Jose Ignacio Baños-Sanz
- Grupo de Cristalografía Macromolecular y Biología Estructural, Instituto de Química-Física ‘Rocasolano’, CSIC, Serrano 119, 28006 Madrid, Spain
| | - Maider Villate
- Grupo de Cristalografía Macromolecular y Biología Estructural, Instituto de Química-Física ‘Rocasolano’, CSIC, Serrano 119, 28006 Madrid, Spain
| | - Julia Sanz-Aparicio
- Grupo de Cristalografía Macromolecular y Biología Estructural, Instituto de Química-Física ‘Rocasolano’, CSIC, Serrano 119, 28006 Madrid, Spain
| | | | - Beatriz González
- Grupo de Cristalografía Macromolecular y Biología Estructural, Instituto de Química-Física ‘Rocasolano’, CSIC, Serrano 119, 28006 Madrid, Spain
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Tsui MM, York JD. Roles of inositol phosphates and inositol pyrophosphates in development, cell signaling and nuclear processes. ACTA ACUST UNITED AC 2009; 50:324-37. [PMID: 20006638 DOI: 10.1016/j.advenzreg.2009.12.002] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Marco M Tsui
- Department of Pharmacology and Cancer Biology, Howard Hughes Medical Institute, Duke University Medical Center, Box 3813, Durham, NC 27710, USA
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Expression of inositol 1,3,4-trisphosphate 5/6-kinase (ITPK1) and its role in neural tube defects. ACTA ACUST UNITED AC 2009; 50:365-72. [PMID: 19914276 DOI: 10.1016/j.advenzreg.2009.10.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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43
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Neural tube defects in mice with reduced levels of inositol 1,3,4-trisphosphate 5/6-kinase. Proc Natl Acad Sci U S A 2009; 106:9831-5. [PMID: 19482943 DOI: 10.1073/pnas.0904172106] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Inositol 1,3,4-trisphosphate 5/6-kinase (ITPK1) is a key regulatory enzyme at the branch point for the synthesis of inositol hexakisphosphate (IP(6)), an intracellular signaling molecule implicated in the regulation of ion channels, endocytosis, exocytosis, transcription, DNA repair, and RNA export from the nucleus. IP(6) also has been shown to be an integral structural component of several proteins. We have generated a mouse strain harboring a beta-galactosidase (betagal) gene trap cassette in the second intron of the Itpk1 gene. Animals homozygous for this gene trap are viable, fertile, and produce less ITPK1 protein than wild-type and heterozygous animals. Thus, the gene trap represents a hypomorphic rather than a null allele. Using a combination of immunohistochemistry, in situ hybridization, and betagal staining of mice heterozygous for the hypomorphic allele, we found high expression of Itpk1 in the developing central and peripheral nervous systems and in the paraxial mesoderm. Examination of embryos resulting from homozygous matings uncovered neural tube defects (NTDs) in some animals and axial skeletal defects or growth retardation in others. On a C57BL/6 x 129(P2)Ola background, 12% of mid-gestation embryos had spina bifida and/or exencephaly, whereas wild-type animals of the same genetic background had no NTDs. We conclude that ITPK1 is required for proper development of the neural tube and axial mesoderm.
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Shears SB. Molecular basis for the integration of inositol phosphate signaling pathways via human ITPK1. ACTA ACUST UNITED AC 2009; 49:87-96. [PMID: 19200440 DOI: 10.1016/j.advenzreg.2008.12.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Stephen B Shears
- Inositol Signaling Section, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, NIH, DHSS, Research Triangle Park, NC 27709, USA.
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45
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Stiles AR, Qian X, Shears SB, Grabau EA. Metabolic and signaling properties of an Itpk gene family in Glycine max. FEBS Lett 2008; 582:1853-8. [PMID: 18474240 PMCID: PMC2515385 DOI: 10.1016/j.febslet.2008.04.054] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2008] [Revised: 04/28/2008] [Accepted: 04/29/2008] [Indexed: 11/21/2022]
Abstract
We have cloned and characterized four Itpk genes from soybean. All four recombinant Itpk proteins showed canonical Ins(1,3,4)P3 5/6-kinase activity, but a kinetic analysis raised questions about its biological significance. Instead, we provide evidence that one alternative biological role for soybean Itpks is to interconvert the Cl(-) channel inhibitor, Ins(3,4,5,6)P4, and its metabolic precursor, Ins(1,3,4,5,6)P5, within a substrate cycle. The soybean Itpks also phosphorylated Ins(3,4,6)P3 to Ins(1,3,4,6)P4 which was further phosphorylated to Ins(1,3,4,5,6)P5 by soybean Ipk2. Thus, soybean Itpks may participate in an inositol lipid-independent pathway of InsP6 synthesis.
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Affiliation(s)
| | | | - Stephen B. Shears
- Department of Plant Pathology, Physiology and Weed Science, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 (A.R.S, E.A.G);, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, NIH, DHSS, Research Triangle Park, NC 27709 (X.Q., S.B.S.)
| | - Elizabeth A. Grabau
- Department of Plant Pathology, Physiology and Weed Science, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 (A.R.S, E.A.G);, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, NIH, DHSS, Research Triangle Park, NC 27709 (X.Q., S.B.S.)
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Majerus PW, Zou J, Marjanovic J, Kisseleva MV, Wilson MP. The role of inositol signaling in the control of apoptosis. ACTA ACUST UNITED AC 2008; 48:10-7. [PMID: 18486622 DOI: 10.1016/j.advenzreg.2008.04.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Philip W Majerus
- Division of Hematology, Washington University School of Medicine, 660 South Euclid, St. Louis, MO 63110, United States.
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Caddick SEK, Harrison CJ, Stavridou I, Mitchell JL, Hemmings AM, Brearley CA. A Solanum tuberosum inositol phosphate kinase (StITPK1) displaying inositol phosphate-inositol phosphate and inositol phosphate-ADP phosphotransferase activities. FEBS Lett 2008; 582:1731-7. [PMID: 18442482 DOI: 10.1016/j.febslet.2008.04.034] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2008] [Revised: 04/10/2008] [Accepted: 04/10/2008] [Indexed: 10/22/2022]
Abstract
We describe a multifunctional inositol polyphosphate kinase/phosphotransferase from Solanum tuberosum, StITPKalpha (GenBank accession number: EF362784), hereafter called StITPK1. StITPK1 displays inositol 3,4,5,6-tetrakisphosphate 1-kinase activity: K(m) = 27 microM, and V(max) = 19 nmol min(-1) mg(-1). The enzyme displays inositol 1,3,4,5,6-pentakisphosphate 1-phosphatase activity in the absence of a nucleotide acceptor and inositol 1,3,4,5,6-pentakisphosphate-ADP phosphotransferase activity in the presence of physiological concentrations of ADP. Additionally, StITPK1 shows inositol phosphate-inositol phosphate phosphotransferase activity. Homology modelling provides a structural rationale of the catalytic abilities of StITPK1. Inter-substrate transfer of phosphate groups between inositol phosphates is an evolutionarily conserved function of enzymes of this class.
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Affiliation(s)
- Samuel E K Caddick
- School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK
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48
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Saiardi A, Cockcroft S. Human ITPK1: a reversible inositol phosphate kinase/phosphatase that links receptor-dependent phospholipase C to Ca2+-activated chloride channels. Sci Signal 2008; 1:pe5. [PMID: 18272466 DOI: 10.1126/stke.14pe5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Inositol 3,4,5,6-tetrakisphosphate [Ins(3,4,5,6)P4] is an inhibitor of the conductance of the Ca(2+)-activated chloride channels in the plasma membrane. These ion channels are required for salt and fluid secretion from epithelial cells, for cell volume homeostasis, and for electrical excitability in neurons and smooth muscle. The enzyme ITPK1 (inositol 1,3,4-triphosphate 5/6 kinase) is the source of Ins(3,4,5,6)P4. It can phosphorylate both Ins(1,3,4)P3 at the 5 or 6 positions and Ins(3,4,5,6)P4 at the 1 position and can also dephosphorylate Ins(1,3,4,5,6)P5 to Ins(3,4,5,6)P4. A study now shows that these various enzyme activities manifested by ITPK1 provide a molecular mechanism that allows the receptor-activated changes in phospholipase C activity and consequent increases in the concentration of Ins(1,3,4)P3 to regulate the abundance of Ins(3,4,5,6)P4. ITPK1 sequesters a tightly bound nucleotide that can accept a phosphate from, or donate a phosphate directly to, an inositol polyphosphate without the nucleotide being released in the bulk medium. This phenomenon of "intersubstrate" transfer is found only in the human enzyme, which can use Ins(1,3,4)P3 to promote increased cellular concentrations of Ins(3,4,5,6)P4.
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Affiliation(s)
- Adolfo Saiardi
- Medical Research Council Cell Biology Unit and Laboratory of Molecular Cell Biology, University College London, London, UK
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Choi JH, Williams J, Cho J, Falck JR, Shears SB. Purification, sequencing, and molecular identification of a mammalian PP-InsP5 kinase that is activated when cells are exposed to hyperosmotic stress. J Biol Chem 2007; 282:30763-75. [PMID: 17702752 PMCID: PMC2366029 DOI: 10.1074/jbc.m704655200] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mammalian cells utilize multiple signaling mechanisms to protect against the osmotic stress that accompanies plasma membrane ion transport, solute uptake, and turnover of protein and carbohydrates (Schliess, F., and Haussinger, D. (2002) Biol. Chem. 383, 577-583). Recently, osmotic stress was found to increase synthesis of bisdiphosphoinositol tetrakisphosphate ((PP)2-InsP4), a high energy inositol pyrophosphate (Pesesse, X., Choi, K., Zhang, T., and Shears, S. B. (2004) J. Biol. Chem. 279, 43378-43381). Here, we describe the purification from rat brain of a diphosphoinositol pentakisphosphate kinase (PPIP5K) that synthesizes (PP)2-InsP4. Partial amino acid sequence, obtained by mass spectrometry, matched the sequence of a 160-kDa rat protein containing a putative ATP-grasp kinase domain. BLAST searches uncovered two human isoforms (PPIP5K1 (160 kDa) and PPIP5K2 (138 kDa)). Recombinant human PPIP5K1, expressed in Escherichia coli, was found to phosphorylate diphosphoinositol pentakisphosphate (PP-InsP5) to (PP)2-InsP4 (Vmax = 8.3 nmol/mg of protein/min; Km = 0.34 microM). Overexpression in human embryonic kidney cells of either PPIP5K1 or PPIP5K2 substantially increased levels of (PP)2-InsP4, whereas overexpression of a catalytically dead PPIP5K1(D332A) mutant had no effect. PPIP5K1 and PPIP5K2 were more active against PP-InsP5 than InsP6, both in vitro and in vivo. Analysis by confocal immunofluorescence showed PPIP5K1 to be distributed throughout the cytoplasm but excluded from the nucleus. Immunopurification of overexpressed PPIP5K1 from osmotically stressed HEK cells (0.2 M sorbitol; 30 min) revealed a persistent, 3.9 +/- 0.4-fold activation when compared with control cells. PPIP5Ks are likely to be important signaling enzymes.
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Affiliation(s)
- Jae H Choi
- Inositide Signaling Group Laboratory of Signal Transduction, NIEHS, National Institutes of Health, DHHS, North Carolina 27709, USA
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50
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Alcázar-Román AR, Wente SR. Inositol polyphosphates: a new frontier for regulating gene expression. Chromosoma 2007; 117:1-13. [DOI: 10.1007/s00412-007-0126-4] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2007] [Revised: 09/12/2007] [Accepted: 09/13/2007] [Indexed: 10/22/2022]
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