1
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Avar M, Heinzer D, Thackray AM, Liu Y, Hruska‐Plochan M, Sellitto S, Schaper E, Pease DP, Yin J, Lakkaraju AKK, Emmenegger M, Losa M, Chincisan A, Hornemann S, Polymenidou M, Bujdoso R, Aguzzi A. An arrayed genome-wide perturbation screen identifies the ribonucleoprotein Hnrnpk as rate-limiting for prion propagation. EMBO J 2022; 41:e112338. [PMID: 36254605 PMCID: PMC9713719 DOI: 10.15252/embj.2022112338] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 09/17/2022] [Accepted: 09/22/2022] [Indexed: 01/15/2023] Open
Abstract
A defining characteristic of mammalian prions is their capacity for self-sustained propagation. Theoretical considerations and experimental evidence suggest that prion propagation is modulated by cell-autonomous and non-autonomous modifiers. Using a novel quantitative phospholipase protection assay (QUIPPER) for high-throughput prion measurements, we performed an arrayed genome-wide RNA interference (RNAi) screen aimed at detecting cellular host-factors that can modify prion propagation. We exposed prion-infected cells in high-density microplates to 35,364 ternary pools of 52,746 siRNAs targeting 17,582 genes representing the majority of the mouse protein-coding transcriptome. We identified 1,191 modulators of prion propagation. While 1,151 modified the expression of both the pathological prion protein, PrPSc , and its cellular counterpart, PrPC , 40 genes selectively affected PrPSc . Of the latter 40 genes, 20 augmented prion production when suppressed. A prominent limiter of prion propagation was the heterogeneous nuclear ribonucleoprotein Hnrnpk. Psammaplysene A (PSA), which binds Hnrnpk, reduced prion levels in cultured cells and protected them from cytotoxicity. PSA also reduced prion levels in infected cerebellar organotypic slices and alleviated locomotor deficits in prion-infected Drosophila melanogaster expressing ovine PrPC . Hence, genome-wide QUIPPER-based perturbations can discover actionable cellular pathways involved in prion propagation. Further, the unexpected identification of a prion-controlling ribonucleoprotein suggests a role for RNA in the generation of infectious prions.
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Affiliation(s)
- Merve Avar
- Institute of NeuropathologyUniversity of ZurichZurichSwitzerland
| | - Daniel Heinzer
- Institute of NeuropathologyUniversity of ZurichZurichSwitzerland
| | - Alana M Thackray
- Department of Veterinary MedicineUniversity of CambridgeCambridgeUK
| | - Yingjun Liu
- Institute of NeuropathologyUniversity of ZurichZurichSwitzerland
| | | | - Stefano Sellitto
- Institute of NeuropathologyUniversity of ZurichZurichSwitzerland
| | - Elke Schaper
- Institute of NeuropathologyUniversity of ZurichZurichSwitzerland
| | - Daniel P Pease
- Institute of NeuropathologyUniversity of ZurichZurichSwitzerland
| | - Jiang‐An Yin
- Institute of NeuropathologyUniversity of ZurichZurichSwitzerland
| | | | - Marc Emmenegger
- Institute of NeuropathologyUniversity of ZurichZurichSwitzerland
| | - Marco Losa
- Institute of NeuropathologyUniversity of ZurichZurichSwitzerland
| | - Andra Chincisan
- Institute of NeuropathologyUniversity of ZurichZurichSwitzerland
| | - Simone Hornemann
- Institute of NeuropathologyUniversity of ZurichZurichSwitzerland
| | | | - Raymond Bujdoso
- Department of Veterinary MedicineUniversity of CambridgeCambridgeUK
| | - Adriano Aguzzi
- Institute of NeuropathologyUniversity of ZurichZurichSwitzerland
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2
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Chen WB, Liu JB, Dou DL, Song FB, Li LY, Xi Z. Synthesis and screening of novel inositol phosphonate derivatives for anticancer functions in vitro. CHINESE CHEM LETT 2015. [DOI: 10.1016/j.cclet.2014.11.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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3
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Witczak ZJ, Sarnik J, Czubatka A, Forma E, Poplawski T. Thio-sugar motif of functional CARB-pharmacophore for antineoplastic activity. Part 2. Bioorg Med Chem Lett 2014; 24:5606-5611. [DOI: 10.1016/j.bmcl.2014.10.095] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 10/27/2014] [Accepted: 10/29/2014] [Indexed: 10/24/2022]
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4
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Witczak ZJ, Poplawski T, Czubatka A, Sarnik J, Tokarz P, VanWert AL, Bielski R. A potential CARB-pharmacophore for antineoplastic activity: Part 1. Bioorg Med Chem Lett 2014; 24:1752-7. [DOI: 10.1016/j.bmcl.2014.02.036] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Revised: 02/10/2014] [Accepted: 02/13/2014] [Indexed: 11/28/2022]
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5
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Yadav M, Raghupathy R, Saikam V, Dara S, Singh PP, Sawant SD, Mayor S, Vishwakarma RA. Synthesis of non-hydrolysable mimics of glycosylphosphatidylinositol (GPI) anchors. Org Biomol Chem 2014; 12:1163-72. [DOI: 10.1039/c3ob42116c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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6
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Mansell D, Veiga N, Torres J, Etchells LL, Bryce RA, Kremer C, Freeman S. Conformational study of the natural iron chelator myo-inositol 1,2,3-trisphosphate using restrained/flexible analogues and computational analysis. Tetrahedron 2010. [DOI: 10.1016/j.tet.2010.09.033] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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7
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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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8
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Mihai C, Yue X, Zhao L, Kravchuk A, Tsai MD, Bruzik KS. Nonhydrolyzable analogs of phosphatidylinositol as ligands of phospholipases C. NEW J CHEM 2010. [DOI: 10.1039/b9nj00629j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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9
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McLean P, Kunjara S, Greenbaum AL, Gumaa K, López-Prados J, Martin-Lomas M, Rademacher TW. Reciprocal control of pyruvate dehydrogenase kinase and phosphatase by inositol phosphoglycans. Dynamic state set by "push-pull" system. J Biol Chem 2008; 283:33428-36. [PMID: 18768479 DOI: 10.1074/jbc.m801781200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Reversible phosphorylation of proteins regulates numerous aspects of cell function, and abnormal phosphorylation is causal in many diseases. Pyruvate dehydrogenase complex (PDC) is central to the regulation of glucose homeostasis. PDC exists in a dynamic equilibrium between de-phospho-(active) and phosphorylated (inactive) forms controlled by pyruvate dehydrogenase phosphatases (PDP1,2) and pyruvate dehydrogenase kinases (PDK1-4). In contrast to the reciprocal regulation of the phospho-/de-phospho cycle of PDC and at the level of expression of the isoforms of PDK and PDP regulated by hormones and diet, there is scant evidence for regulatory factors acting in vivo as reciprocal "on-off" switches. Here we show that the putative insulin mediator inositol phosphoglycan P-type (IPG-P) has a sigmoidal inhibitory action on PDK in addition to its known linear stimulation of PDP. Thus, at critical levels of IPG-P, this sigmoidal/linear model markedly enhances the switchover from the inactive to the active form of PDC, a "push-pull" system that, combined with the developmental and hormonal control of IPG-P, indicates their powerful regulatory function. The release of IPGs from cell membranes by insulin is significant in relation to diabetes. The chelation of IPGs with Mn2+ and Zn2+ suggests a role as "catalytic chelators" coordinating the traffic of metal ions in cells. Synthetic inositol hexosamine analogues are shown here to have a similar linear/sigmoidal reciprocal action on PDC exerting push-pull effects, suggesting their potential for treatment of metabolic disorders, including diabetes.
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Affiliation(s)
- Patricia McLean
- Division of Infection and Immunity, University College London Medical School, London W1T 4JF, United Kingdom
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10
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Gajewiak J, Tsukahara R, Tsukahara T, Fujiwara Y, Yu S, Lu Y, Murph M, Mills GB, Tigyi G, Prestwich GD. Alkoxymethylenephosphonate analogues of (Lyso) phosphatidic acid stimulate signaling networks coupled to the LPA2 receptor. ChemMedChem 2008; 2:1789-98. [PMID: 17952880 DOI: 10.1002/cmdc.200700111] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
An efficient stereocontrolled synthesis afforded alkoxymethylenephosphonate (MP) analogues of lysophosphatidic acid (LPA) and phosphatidic acid (PA). The pharmacological properties of MP-LPA and MP-PA analogues were characterized for LPA receptor subtype-specific agonist and antagonist activity using Ca(2+)-mobilization assays in RH7777 cells expressing the individual LPA(1)-LPA(3) receptors and CHO cells expressing LPA(4). In addition, activation of a PPARgamma reporter gene construct expressed in CV-1 cells was assessed. These metabolically stabilized LPA analogues exhibited an unexpected pattern of partial agonist/antagonist activity for the LPA G-protein-coupled receptor family and the intracellular LPA receptor PPARgamma. Analogues were compared with 18:1 LPA for activation of downstream signaling in HT-29 colon cancer cells, which exclusively express LPA(2), and both SKOV3 and OVCAR3 ovarian cancer cells, which express LPA(1), LPA(2), and LPA(3). Unexpectedly, reverse phase protein arrays showed that four MP-LPA and MP-PA analogues selectively activated downstream signaling in HT-29 cells with greater potency than LPA. In particular, the oleoyl MP-LPA analogue strongly promoted phosphorylation and activation of AKT, MEK, and pS6 in HT-29 cells in a concentration-dependent manner. In contrast, the four MP-LPA and MP-PA analogues were equipotent with LPA for pathway activation in the SKOV3 and OVCAR3 cells. Taken together, these results suggest that the MP analogues may selectively activate signaling via the LPA(2) receptor subtype, while simultaneously suppressing signaling through the LPA(1) and LPA(3) subtypes.
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Affiliation(s)
- Joanna Gajewiak
- Department of Medicinal Chemistry, University of Utah, 419 Wakara Way, Suite 205, Salt Lake City, UT 84108-1257, USA
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11
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Schmolke M, Fabian J, Lehr M. High-performance liquid chromatographic assay with ultraviolet spectrometric detection for the evaluation of inhibitors of phosphatidylinositol-specific phospholipase C. Anal Biochem 2008; 375:291-8. [DOI: 10.1016/j.ab.2007.12.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2007] [Revised: 12/19/2007] [Accepted: 12/19/2007] [Indexed: 11/30/2022]
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12
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Gajewiak J, Tsukahara R, Fujiwara Y, Tigyi G, Prestwich GD. Synthesis, pharmacology, and cell biology of sn-2-aminooxy analogues of lysophosphatidic acid. Org Lett 2008; 10:1111-4. [PMID: 18284246 DOI: 10.1021/ol7030747] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An efficient enantioselective synthesis of sn-2-aminooxy (AO) analogues of lysophosphatidic acid (LPA) that possess palmitoyl and oleoyl acyl chains is presented. Both sn-2-AO LPA analogues are agonists for the LPA1, LPA2, and LPA4 G-protein-coupled receptors, but antagonists for the LPA3 receptor and inhibitors of autotaxin (ATX). Moreover, both analogues stimulate migration of intestinal epithelial cells in a scratch wound assay.
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Affiliation(s)
- Joanna Gajewiak
- Department of Medicinal Chemistry, The University of Utah, 419 Wakara Way, Salt Lake City, UT 84108-1257, USA
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13
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Hornemann S, Schorn C, Wüthrich K. NMR structure of the bovine prion protein isolated from healthy calf brains. EMBO Rep 2004; 5:1159-64. [PMID: 15568016 PMCID: PMC1299192 DOI: 10.1038/sj.embor.7400297] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2004] [Revised: 10/20/2004] [Accepted: 10/21/2004] [Indexed: 11/09/2022] Open
Abstract
NMR structures of recombinant prion proteins from various species expressed in Escherichia coli have been solved during the past years, but the fundamental question of the relevancy of these data relative to the naturally occurring forms of the prion protein has not been directly addressed. Here, we present a comparison of the cellular form of the bovine prion protein isolated and purified from healthy calf brains without use of detergents, so that it contains the two carbohydrate moieties and the part of the GPI anchor that is maintained after enzymatic cleavage of the glycerolipid moiety, with the recombinant bovine prion protein expressed in E. coli. We show by circular dichroism and (1)H-NMR spectroscopy that the three-dimensional structure and the thermal stability of the natural glycoprotein and the recombinant polypeptide are essentially identical. This result indicates possible functional roles of the glycosylation of prion proteins in healthy organisms, and provides a platform and validation for future work on the structural biology of prion proteins, which will have to rely primarily on the use of recombinant polypeptides.
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Affiliation(s)
- Simone Hornemann
- Institut für Molekularbiologie und Biophysik, Eidgenössische Technische Hochschule Zürich, 8093 Zürich, Switzerland.
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14
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Birrell GB, Zaikova TO, Rukavishnikov AV, Keana JFW, Griffith OH. Allosteric interactions within subsites of a monomeric enzyme: kinetics of fluorogenic substrates of PI-specific phospholipase C. Biophys J 2003; 84:3264-75. [PMID: 12719256 PMCID: PMC1302887 DOI: 10.1016/s0006-3495(03)70051-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Two novel water-soluble fluorescein myo-inositol phosphate (FLIP) substrates, butyl-FLIP and methyl-FLIP, were used to examine the kinetics and subsite interactions of Bacillus cereus phosphatidylinositol-specific phospholipase C. Butyl-FLIP exhibited sigmoidal kinetics when initial rates are plotted versus substrate concentration. The data fit a Hill coefficient of 1.2-1.5, suggesting an allosteric interaction between two sites. Two substrate molecules bind to this enzyme, one at the active site and one at a subsite, causing an increase in activity. The kinetic behavior is mathematically similar to that of well-known cooperative multimeric enzymes even though this phosphatidylinositol-specific phospholipase C is a small, monomeric enzyme. The less hydrophobic substrate, methyl-FLIP, binds only to the active site and not the activator site, and thus exhibits standard hyperbolic kinetics. An analytical expression is presented that accounts for the kinetics of both substrates in the absence and presence of a nonsubstrate short-chain phospholipid, dihexanoylphosphatidylcholine. The fluorogenic substrates detect activation at much lower concentrations of dihexanoylphosphatidylcholine than previously reported.
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Affiliation(s)
- G Bruce Birrell
- Institute of Molecular Biology and Department of Chemistry, University of Oregon, Eugene, OR 97403, USA
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15
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Stanton JD, Rashid MB, Mensa-Wilmot K. Cysteine-less glycosylphosphatidylinositol-specific phospholipase C is inhibited competitively by a thiol reagent: evidence for glyco-mimicry by p-chloromercuriphenylsulphonate. Biochem J 2002; 366:281-8. [PMID: 12010122 PMCID: PMC1222759 DOI: 10.1042/bj20020367] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2002] [Revised: 05/10/2002] [Accepted: 05/15/2002] [Indexed: 11/17/2022]
Abstract
Glycosylphosphatidylinositol (GPI)-specific phospholipases are highly valuable for studying the structure and function of GPIs. GPI-specific phospholipase C (GPI-PLC) from Trypanosoma brucei and phosphatidylinositol-specific phospholipase C (PI-PLC) from Bacillus cereus are the most widely studied of this class of phospholipases C. Inhibition of protein activity by thiol reagents is indicative of the participation of cysteine residues in biochemical events. The thiol reagent p-chloromercuriphenylsulphonate (pCMPS) inhibits T. brucei GPI-PLC, which has eight cysteine residues. Surprisingly, we found that the activity of B. cereus PI-PLC is also blocked by pCMPS, although the protein does not contain cysteine residues. Inhibition of B. cereus PI-PLC was reversed when pCMPS was size-separated from a preformed pCMPS.PI-PLC complex. In contrast, no activity was recovered when T. brucei GPI-PLC was subjected to a similar protocol. Equimolar beta-mercaptoethanol (beta-ME) reversed the inhibition of PI-PLC activity in a pCMPS.PI-PLC complex. For T. brucei GPI-PLC, however, ultrafiltration of the pCMPS.GI-PLC complex and addition of a large excess of beta-ME was necessary for partial recovery of enzyme activity. Thus T. brucei GPI-PLC is susceptible to inactivation by covalent modification with pCMPS, whereas PI-PLC is not. Kinetic analysis indicated that pCMPS was a competitive inhibitor of PI-PLC when a GPI was a substrate. Curiously, with phosphatidylinositol as substrate, inhibition was no longer competitive. These data suggest that pCMPS is a glyco-mimetic that occupies the glycan binding site of PI-PLC, from where, depending on the substrate, it inhibits catalysis allosterically or competitively.
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Affiliation(s)
- Julie D Stanton
- Department of Cellular Biology, The University of Georgia, 724 Biological Sciences, Athens, GA 30602, U.S.A
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16
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Ryan M, Liu T, Dahlquist FW, Griffith OH. A catalytic diad involved in substrate-assisted catalysis: NMR study of hydrogen bonding and dynamics at the active site of phosphatidylinositol-specific phospholipase C. Biochemistry 2001; 40:9743-50. [PMID: 11583175 DOI: 10.1021/bi010958m] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Phosphatidylinositol-specific phospholipase Cs (PI-PLCs, EC 3.1.4.10) are ubiquitous enzymes that cleave phosphatidylinositol or phosphorylated derivatives, generating second messengers in eukaryotic cells. A catalytic diad at the active site of Bacillus cereus PI-PLC composed of aspartate-274 and histidine-32 was postulated from the crystal structure to form a catalytic triad with the 2-OH group of the substrate [Heinz, D. W., et al. (1995) EMBO J. 14, 3855-3863]. This catalytic diad has been observed directly by proton NMR. The single low-field line in the 1H NMR spectrum is assigned by site-directed mutagenesis: The peak is present in the wild type but absent in the mutants H32A and D274A, and arises from the histidine Hdelta1 forming the Asp274-His32 hydrogen bond. This hydrogen is solvent-accessible, and exchanges slowly with H2O on the NMR time scale. The position of the low-field peak shifts from 16.3 to 13.8 ppm as the pH is varied from 4 to 9, reflecting a pKa of 8.0 at 6 degrees C, which is identified with the pKa of His32. The Hdelta1 signal is modulated by rapid exchange of the Hepsilon2 with the solvent. Estimates of the exchange rate as a function of pH and protection factors are derived from a line shape analysis. The NMR behavior is remarkably similar to that of the serine proteases. The postulated function of the Asp274-His32 diad is to hydrogen-bond with the 2-OH of phosphatidylinositol (PI) substrate to form a catalytic triad analogous to Asp-His-Ser of serine proteases. This is an example of substrate-assisted catalysis where the substrate provides the catalytic nucleophile of the triad. This hydrogen bond becomes shorter as the imidazole is protonated, suggesting it is stronger in the transition state, contributing further to the catalytic efficiency. The hydrogen bond fits the NMR criteria for a short, strong hydrogen bond, i.e., a highly deshielded proton resonance, bond length of 2.64 +/- 0.04 A at pH 6 measured by NMR, a D/H fractionation factor significantly lower than 1.0, and a protection factor > or = 100.
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Affiliation(s)
- M Ryan
- Institute of Molecular Biology and Department of Chemistry, University of Oregon, Eugene 97403, USA
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17
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Hedberg KK, Cogan EB, Birrell GB, Griffith OH. Sensitive fluorescent quantitation of myo-inositol 1,2-cyclic phosphate and myo-inositol 1-phosphate by high-performance thin-layer chromatography. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 2001; 757:317-24. [PMID: 11417877 DOI: 10.1016/s0378-4347(01)00169-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A non-radioactive micro-assay for the cyclic phosphodiesterase reaction catalyzed by Bacillus cereus phosphatidylinositol-specific phospholipase C is described. The assay involves high-performance thin-layer chromatography on silica gel to resolve the substrate (myo-inositol 1,2-cyclic phosphate) and the product (myo-inositol 1-phosphate), followed by detection with a lead tetraacetate-fluorescein stain. The quantitation of these inositol phosphates in sample spots relative to a series of standards is accomplished by analysis of the fluorescent plate image with a commercial phosphoimager and associated software. The experimental considerations for reliable quantitation of inositol monophosphates in the range of 0.1 to 50 nmol are presented.
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Affiliation(s)
- K K Hedberg
- Department of Chemistry, University of Oregon, Eugene 97403, USA
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18
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Ciuffreda P, Loseto A, Manzocchi A, Santaniello E. Lipolytic activity of porcine pancreas lipase on fatty acid esters of dialkylglycerols: a structural basis for the design of new substrates for the assay of pancreatic lipases activity. Chem Phys Lipids 2001; 111:105-10. [PMID: 11457440 DOI: 10.1016/s0009-3084(01)00143-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
For the design of new synthetic substrates for the assay of pancreatic lipases activity, acyl dialkylglycerols of variable chain length were prepared. Titrimetric assay of these substrates showed the highest lipolytic activity of porcine pancreas lipase (pPL) with butanoyl dibutylglycerol. The activity is lower but comparable to that shown by pPL towards the classical substrate tributyrin. The 4-nitrophenylcarbonate of 1,2-di-O-butylglycerol, has been prepared and proposed as synthetic substrate for a new spectrophotometric assay of pancreatic lipases.
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Affiliation(s)
- P Ciuffreda
- Dipartimento di Scenze Precliniche LITA Vialba-Via G.B. Grassi, 74-20157, Milan, Italy
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19
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Zaikova TO, Rukavishnikov AV, Birrell GB, Griffith OH, Keana JF. Synthesis of fluorogenic substrates for continuous assay of phosphatidylinositol-specific phospholipase C. Bioconjug Chem 2001; 12:307-13. [PMID: 11312693 DOI: 10.1021/bc0001138] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An improved synthesis of fluorogenic substrate analogues for phosphatidylinositol-specific phospholipase C (PI-PLC) is described. The water-soluble substrates, which are derived from fluorescein, are not fluorescent until cleaved by the enzyme, and provide a convenient means to continuously monitor PI-PLC activity. The improvement in the synthesis lies in the method used to protect the hydroxyl groups of the inositol portion of the substrate molecule and allows a milder deprotection procedure to be used. The result is a much more reproducible synthesis of the substrate. The improved procedure has been employed to synthesize a series of fluorogenic substrates, which differ in the length of the aliphatic tail attached to the fluorescein portion of the molecule. The length of the tail was found to have a significant effect on the rate of cleavage of these substrates.
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Affiliation(s)
- T O Zaikova
- Department of Chemistry and Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403, USA
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Frontier AJ, Raghavan S, Danishefsky SJ. A Highly Stereoselective Total Synthesis of Hispidospermidin: Derivation of a Pharmacophore Model. J Am Chem Soc 2000. [DOI: 10.1021/ja9944960] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Alison J. Frontier
- Contribution from the Department of Chemistry, Columbia University, Havemeyer Hall, New York, New York 10027, and the Laboratory for Bioorganic Chemistry, the Sloan-Kettering Institute for Cancer Research, 1275 York Avenue, New York, New York 10021
| | - Subharekha Raghavan
- Contribution from the Department of Chemistry, Columbia University, Havemeyer Hall, New York, New York 10027, and the Laboratory for Bioorganic Chemistry, the Sloan-Kettering Institute for Cancer Research, 1275 York Avenue, New York, New York 10021
| | - Samuel J. Danishefsky
- Contribution from the Department of Chemistry, Columbia University, Havemeyer Hall, New York, New York 10027, and the Laboratory for Bioorganic Chemistry, the Sloan-Kettering Institute for Cancer Research, 1275 York Avenue, New York, New York 10021
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21
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Griffith OH, Ryan M. Bacterial phosphatidylinositol-specific phospholipase C: structure, function, and interaction with lipids. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1441:237-54. [PMID: 10570252 DOI: 10.1016/s1388-1981(99)00153-5] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The bacterial phosphatidylinositol-specific phospholipase C (PI-PLC) is a small, water-soluble enzyme that cleaves the natural membrane lipids PI, lyso-PI, and glycosyl-PI. The crystal structure, NMR and enzymatic mechanism of bacterial PI-PLCs are reviewed. These enzymes consist of a single domain folded as a (betaalpha)(8)-barrel (TIM barrel), are calcium-independent, and interact weakly with membranes. Sequence similarity among PI-PLCs from different bacterial species is extensive, and includes the residues involved in catalysis. Bacterial PI-PLCs are structurally similar to the catalytic domain of mammalian PI-PLCs. Comparative studies of both prokaryotic and eukaryotic isozymes have proved useful for the identification of distinct regions of the proteins that are structurally and functionally important.
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Affiliation(s)
- O H Griffith
- Institute of Molecular Biology and Department of Chemistry, University of Oregon, Eugene, OR 97403, USA.
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Lin W, Leung LW, Bae YS, Bittman R, Arthur G. Effects of a water-soluble antitumor ether phosphonoinositide, D-myo-inositol 4-(hexadecyloxy)-3(S)-methoxybutanephosphonate (C4-PI), on inositol lipid metabolism in breast epithelial cancer cell lines. Biochem Pharmacol 1999; 57:1153-8. [PMID: 11230803 DOI: 10.1016/s0006-2952(99)00019-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
We have demonstrated previously that D-myo-inositol 4-(hexadecyloxy)-3(S)-methoxybutanephosphonate (C4-PI), an isosteric phosphonate analog of phosphatidylinositol developed to inhibit inositol lipid metabolism, was unable to inhibit phosphatidylinositol (PI) 3-kinase activity. We now report the effects of the compound on other aspects of inositol metabolism. We demonstrated that C4-PI inhibits the activity of purified recombinant PI-phospholipase C-beta (PLC-beta) at all concentrations tested; it enhanced the activity of PI-PLC-gamma and PI-PLC-delta at low concentrations (10 microM), while severely inhibiting their activities at higher concentrations. In the breast cancer cell lines MCF-7 (estrogen receptor positive) and MDA-MB-468 (estrogen receptor negative), C4-PI had no effect on the uptake of D-myo-inositol but severely inhibited its incorporation into PI. In spite of the drastic decrease in PI synthesis, C4-PI did not affect the levels of inositol incorporated into phosphatidylinositol 4,5-bisphosphate (PIP2) in the cells. In vitro assays showed that C4-PI inhibited PI synthase activity (inhibition of 35% at 50 microM) but had little effect on PI 4-kinase activity (inhibition of 13% at 150 microM). C4-PI inhibited the proliferation of MCF-7 and MDA-MB-468 cell lines with IC(50) values of 12 and 18 microM. Taken together, the results suggest that the accumulation of [3H]inositol in PIP2 in cells incubated with C4-PI may be due to the inhibition of PIP2 hydrolysis in the cells with no effect on its synthesis. The role of these C4-PI-induced effects in the mechanism of growth inhibition by C4-PI remains to be established.
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Affiliation(s)
- W Lin
- Department of Biochemistry and Molecular Biology, University of Manitoba, Winnipeg, Manitoba, Canada
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Recombinant Bacillus subtilis whole cell system as a catalyst for enzymatic synthesis of cyclic inositol phosphate. Tetrahedron Lett 1998. [DOI: 10.1016/s0040-4039(98)01250-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Rukavishnikov AV, Zaikova TO, Griffith OH, Keana JF. Improved synthesis of myo-inositol 1-(4-nitrophenyl hydrogen phosphate), a chromogenic substrate for phosphatidylinositol-specific phospholipase C. Chem Phys Lipids 1997; 89:153-7. [PMID: 9369010 DOI: 10.1016/s0009-3084(97)00069-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- A V Rukavishnikov
- Department of Chemistry, University of Oregon, Eugene 97403-1229, USA
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Gässler CS, Ryan M, Liu T, Griffith OH, Heinz DW. Probing the roles of active site residues in phosphatidylinositol-specific phospholipase C from Bacillus cereus by site-directed mutagenesis. Biochemistry 1997; 36:12802-13. [PMID: 9335537 DOI: 10.1021/bi971102d] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The role of amino acid residues located in the active site pocket of phosphatidylinositol-specific phospholipase C (PI-PLC) from Bacillus cereus[Heinz, D. W., Ryan, M., Bullock, T., & Griffith, O. H. (1995) EMBO J. 14, 3855-3863] was investigated by site-directed mutagenesis, kinetics, and crystal structure analysis. Twelve residues involved in catalysis and substrate binding (His32, Arg69, His82, Gly83, Lys115, Glu117, Arg163, Trp178, Asp180, Asp198, Tyr200, and Asp274) were individually replaced by 1-3 other amino acids, resulting in a total number of 21 mutants. Replacements in the mutants H32A, H32L, R69A, R69E, R69K, H82A, H82L, E117K, R163I, D198A, D198E, D198S, Y200S, and D274S caused essentially complete inactivation of the enzyme. The remaining mutants (G83S, K115E, R163K, W178Y, D180S, Y200F, and D274N) exhibited reduced activities up to 57% when compared with wild-type PI-PLC. Crystal structures determined at a resolution ranging from 2.0 to 2.7 A for six mutants (H32A, H32L, R163K, D198E, D274N, and D274S) showed that significant changes were confined to the site of the respective mutation without perturbation of the rest of the structure. Only in mutant D198E do the side chains of two neighboring arginine residues move across the inositol binding pocket toward the newly introduced glutamic acid. An analysis of these structure-function relationships provides new insight into the catalytic mechanism, and suggests a molecular explanation of some of the substrate stereospecificity and inhibitor binding data available for this enzyme.
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Affiliation(s)
- C S Gässler
- Institut für Organische Chemie und Biochemie, Universität Freiburg, D-79104 Freiburg, Germany
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