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Straube H, Straube J, Rinne J, Fischer L, Niehaus M, Witte CP, Herde M. An inosine triphosphate pyrophosphatase safeguards plant nucleic acids from aberrant purine nucleotides. THE NEW PHYTOLOGIST 2023; 237:1759-1775. [PMID: 36464781 DOI: 10.1111/nph.18656] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 11/22/2022] [Indexed: 06/17/2023]
Abstract
In plants, inosine is enzymatically introduced in some tRNAs, but not in other RNAs or DNA. Nonetheless, our data show that RNA and DNA from Arabidopsis thaliana contain (deoxy)inosine, probably derived from nonenzymatic adenosine deamination in nucleic acids and usage of (deoxy)inosine triphosphate (dITP and ITP) during nucleic acid synthesis. We combined biochemical approaches, LC-MS, as well as RNA-Seq to characterize a plant INOSINE TRIPHOSPHATE PYROPHOSPHATASE (ITPA) from A. thaliana, which is conserved in many organisms, and investigated the sources of deaminated purine nucleotides in plants. Inosine triphosphate pyrophosphatase dephosphorylates deaminated nucleoside di- and triphosphates to the respective monophosphates. ITPA loss-of-function causes inosine di- and triphosphate accumulation in vivo and an elevated inosine and deoxyinosine content in RNA and DNA, respectively, as well as salicylic acid (SA) accumulation, early senescence, and upregulation of transcripts associated with immunity and senescence. Cadmium-induced oxidative stress and biochemical inhibition of the INOSINE MONOPHOSPHATE DEHYDROGENASE leads to more IDP and ITP in the wild-type (WT), and this effect is enhanced in itpa mutants, suggesting that ITP originates from ATP deamination and IMP phosphorylation. Inosine triphosphate pyrophosphatase is part of a molecular protection system in plants, preventing the accumulation of (d)ITP and its usage for nucleic acid synthesis.
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Affiliation(s)
- Henryk Straube
- Department of Molecular Nutrition and Biochemistry of Plants, Leibniz Universität Hannover, Hannover, 30419, Germany
| | - Jannis Straube
- Department of Molecular Plant Breeding, Leibniz Universität Hannover, Hannover, 30419, Germany
| | - Jannis Rinne
- Department of Molecular Nutrition and Biochemistry of Plants, Leibniz Universität Hannover, Hannover, 30419, Germany
| | - Lisa Fischer
- Department of Molecular Nutrition and Biochemistry of Plants, Leibniz Universität Hannover, Hannover, 30419, Germany
| | - Markus Niehaus
- Department of Molecular Nutrition and Biochemistry of Plants, Leibniz Universität Hannover, Hannover, 30419, Germany
| | - Claus-Peter Witte
- Department of Molecular Nutrition and Biochemistry of Plants, Leibniz Universität Hannover, Hannover, 30419, Germany
| | - Marco Herde
- Department of Molecular Nutrition and Biochemistry of Plants, Leibniz Universität Hannover, Hannover, 30419, Germany
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James AM, Seal SE, Bailey AM, Foster GD. Viral inosine triphosphatase: A mysterious enzyme with typical activity, but an atypical function. MOLECULAR PLANT PATHOLOGY 2021; 22:382-389. [PMID: 33471956 PMCID: PMC7865087 DOI: 10.1111/mpp.13021] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 10/22/2020] [Accepted: 10/23/2020] [Indexed: 05/03/2023]
Abstract
Plant viruses typically have highly condensed genomes, yet the plant-pathogenic viruses Cassava brown streak virus, Ugandan cassava brown streak virus, and Euphorbia ringspot virus are unusual in encoding an enzyme not yet found in any other virus, the "house-cleaning" enzyme inosine triphosphatase. Inosine triphosphatases (ITPases) are highly conserved enzymes that occur in all kingdoms of life and perform a house-cleaning function by hydrolysing the noncanonical nucleotide inosine triphosphate to inosine monophosphate. The ITPases encoded by cassava brown streak virus and Ugandan cassava brown streak virus have been characterized biochemically and are shown to have typical ITPase activity. However, their biological role in virus infection has yet to be elucidated. Here we review what is known of viral-encoded ITPases and speculate on potential roles in infection with the aim of generating a greater understanding of cassava brown streak viruses, a group of the world's most devastating viruses.
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Affiliation(s)
- Amy M. James
- School of Biological SciencesLife Sciences BuildingUniversity of BristolBristolUK
| | - Susan E. Seal
- Natural Resources Institute, Chatham MaritimeGillinghamUK
| | - Andy M. Bailey
- School of Biological SciencesLife Sciences BuildingUniversity of BristolBristolUK
| | - Gary D. Foster
- School of Biological SciencesLife Sciences BuildingUniversity of BristolBristolUK
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Abstract
Traditionally, only the 3',5'-cyclic monophosphates of adenosine and guanosine (produced by adenylyl cyclase and guanylyl cyclase, respectively) are regarded as true "second messengers" in the vascular wall, despite the presence of other cyclic nucleotides in different tissues. Among these noncanonical cyclic nucleotides, inosine 3',5'-cyclic monophosphate (cIMP) is synthesized by soluble guanylyl cyclase in porcine coronary arteries in response to hypoxia, when the enzyme is activated by endothelium-derived nitric oxide. Its production is associated with augmentation of vascular contraction mediated by stimulation of Rho kinase. Based on these findings, cIMP appears to meet most, if not all, of the criteria required for it to be accepted as a "second messenger," at least in the vascular wall.
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Glioblastoma and glioblastoma stem cells are dependent on functional MTH1. Oncotarget 2017; 8:84671-84684. [PMID: 29156675 PMCID: PMC5689565 DOI: 10.18632/oncotarget.19404] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 07/03/2017] [Indexed: 02/07/2023] Open
Abstract
Glioblastoma multiforme (GBM) is an aggressive form of brain cancer with poor prognosis. Cancer cells are characterized by a specific redox environment that adjusts metabolism to its specific needs and allows the tumor to grow and metastasize. As a consequence, cancer cells and especially GBM cells suffer from elevated oxidative pressure which requires antioxidant-defense and other sanitation enzymes to be upregulated. MTH1, which degrades oxidized nucleotides, is one of these defense enzymes and represents a promising cancer target. We found MTH1 expression levels elevated and correlated with GBM aggressiveness and discovered that siRNA knock-down or inhibition of MTH1 with small molecules efficiently reduced viability of patient-derived GBM cultures. The effect of MTH1 loss on GBM viability was likely mediated through incorporation of oxidized nucleotides and subsequent DNA damage. We revealed that MTH1 inhibition targets GBM independent of aggressiveness as well as potently kills putative GBM stem cells in vitro. We used an orthotopic zebrafish model to confirm our results in vivo and light-sheet microscopy to follow the effect of MTH1 inhibition in GBM in real time. In conclusion, MTH1 represents a promising target for GBM therapy and MTH1 inhibitors may also be effective in patients that suffer from recurring disease.
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Trans DJ, Bai R, Addison JB, Liu R, Hamel E, Coleman MA, Henderson PT. Synthesis of two fluorescent GTPγS molecules and their biological relevance. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2017; 36:379-391. [PMID: 28282254 DOI: 10.1080/15257770.2016.1231320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Fluorescent GTP analogues are utilized for an assortment of nucleic acid and protein characterization studies. Non-hydrolysable analogues such as GTPγS offer the advantage of keeping proteins in a GTP-bound conformation due to their resistance to hydrolysis into GDP. Two novel fluorescent GTPγS molecules were developed by linking fluorescein and tetramethylrhodamine to the γ-thiophosphate of GTPγS. Chemical and biological analysis of these two compounds revealed their successful synthesis and ability to bind to the nucleotide-binding site of tubulin. These two new fluorescent non-hydrolysable nucleotides offer new possibilities for biophysical and biochemical characterization of GTP-binding proteins.
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Affiliation(s)
- Denise J Trans
- a Department of Internal Medicine and UC Davis Comprehensive Cancer Center , University of California , Davis , CA , USA
| | - Ruoli Bai
- b Screening Technologies Branch, Developmental Therapeutics Program, Division of Cancer Treatment and Diagnosis, National Cancer Institute, Frederick National Laboratory for Cancer Research , National Institutes of Health , Frederick , MD , USA
| | - J Bennet Addison
- c Nuclear Magnetic Resonance Facility , University of California , Davis , CA , USA
| | - Ruiwu Liu
- d Department of Biochemistry and Molecular Medicine , University of California , Davis , CA , USA
| | - Ernest Hamel
- b Screening Technologies Branch, Developmental Therapeutics Program, Division of Cancer Treatment and Diagnosis, National Cancer Institute, Frederick National Laboratory for Cancer Research , National Institutes of Health , Frederick , MD , USA
| | - Matthew A Coleman
- e Department of Radiation Oncology , University of California , Davis , CA , USA.,f Lawrence Livermore National Laboratory , Livermore , CA , USA
| | - Paul T Henderson
- a Department of Internal Medicine and UC Davis Comprehensive Cancer Center , University of California , Davis , CA , USA
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Huecas S, Marcelo F, Perona A, Ruiz-Ávila LB, Morreale A, Cañada FJ, Jiménez-Barbero J, Andreu JM. Beyond a Fluorescent Probe: Inhibition of Cell Division Protein FtsZ by mant-GTP Elucidated by NMR and Biochemical Approaches. ACS Chem Biol 2015; 10:2382-92. [PMID: 26247422 DOI: 10.1021/acschembio.5b00444] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
FtsZ is the organizer of cell division in most bacteria and a target in the quest for new antibiotics. FtsZ is a tubulin-like GTPase, in which the active site is completed at the interface with the next subunit in an assembled FtsZ filament. Fluorescent mant-GTP has been extensively used for competitive binding studies of nucleotide analogs and synthetic GTP-replacing inhibitors possessing antibacterial activity. However, its mode of binding and whether the mant tag interferes with FtsZ assembly function were unknown. Mant-GTP exists in equilibrium as a mixture of C2'- and C3'-substituted isomers. We have unraveled the molecular recognition process of mant-GTP by FtsZ monomers. Both isomers bind in the anti glycosidic bond conformation: 2'-mant-GTP in two ribose puckering conformations and 3'-mant-GTP in the preferred C2' endo conformation. In each case, the mant tag strongly interacts with FtsZ at an extension of the GTP binding site, which is also supported by molecular dynamics simulations. Importantly, mant-GTP binding induces archaeal FtsZ polymerization into inactive curved filaments that cannot hydrolyze the nucleotide, rather than straight GTP-hydrolyzing assemblies, and also inhibits normal assembly of FtsZ from the Gram-negative bacterium Escherichia coli but is hydrolyzed by FtsZ from Gram-positive Bacillus subtilis. Thus, the specific interactions provided by the fluorescent mant tag indicate a new way to search for synthetic FtsZ inhibitors that selectively suppress the cell division of bacterial pathogens.
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Affiliation(s)
- Sonia Huecas
- Centro de Investigaciones
Biológicas, CIB-CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Filipa Marcelo
- Centro de Investigaciones
Biológicas, CIB-CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
- UCIBIO, REQUIMTE, Dept. de Química, Faculdade de Ciências
e Tecnologia, UNL, 2829-516 Caparica, Portugal
| | - Almudena Perona
- Unidad de Bioinformática,
Centro de Biología Molecular Severo Ochoa, CBMSO−CSIC, Cantoblanco, 28049 Madrid, Spain
| | - Laura B. Ruiz-Ávila
- Centro de Investigaciones
Biológicas, CIB-CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Antonio Morreale
- Unidad de Bioinformática,
Centro de Biología Molecular Severo Ochoa, CBMSO−CSIC, Cantoblanco, 28049 Madrid, Spain
| | - F. Javier Cañada
- Centro de Investigaciones
Biológicas, CIB-CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Jesús Jiménez-Barbero
- Centro de Investigaciones
Biológicas, CIB-CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - José M. Andreu
- Centro de Investigaciones
Biológicas, CIB-CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
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Nakajima KI, Niisato N, Marunaka Y. Enhancement of tubulin polymerization by Cl(-)-induced blockade of intrinsic GTPase. Biochem Biophys Res Commun 2012; 425:225-9. [PMID: 22828510 DOI: 10.1016/j.bbrc.2012.07.072] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 07/14/2012] [Indexed: 01/03/2023]
Abstract
In growing neurite of neuronal cells, it is suggested that α/β-tubulin heterodimers assemble to form microtubule, and assembly of microtubule promotes neurite elongation. On the other hand, recent studies reveal importance of intracellular Cl(-) in regulation of various cellular functions such as cell cycle progression, differentiation, cell migration, and elongation of neurite in neuronal cells. In this study, we investigated effects of Cl(-) on in vitro tubulin polymerization. We found that efficiency of in vitro tubulin polymerization (the number of microtubule) was higher (3 to 5-fold) in Cl(-)-containing solutions than that in Cl(-)-free solutions containing Br(-) or NO(3)(-). On the other hand, GTPase activity of tubulin was lower (2/3-fold) in Cl(-)-containing solutions than that in Cl(-)-free solutions containing Br(-) or NO(3)(-). Efficiency of in vitro tubulin polymerization in solutions containing a non-hydrolyzable analogue of GTP (GpCpp) instead of GTP was much higher than that in the presence of GTP. Effects of replacement of GTP with GpCpp on in vitro tubulin polymerization was weaker in Cl(-) solutions (10-fold increases) than that in Br(-) or NO(3)(-) solutions (20-fold increases), although the efficiency of in vitro tubulin polymerization in Cl(-) solutions containing GpCpp was still higher than that in Br(-) or NO(3)(-) solutions containing GpCpp. Our results suggest that a part of stimulatory effects of Cl(-) on in vitro tubulin polymerization is mediated via an inhibitory effect on GTPase activity of tubulin, although Cl(-) would also regulate in vitro tubulin polymerization by factors other than an inhibitory effect on GTPase activity.
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Affiliation(s)
- Ken-ichi Nakajima
- Department of Molecular Cell Physiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.
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A fluorescent GTP analog as a specific, high-precision label of microtubules. Biotechniques 2011; 51:43-8. [PMID: 21781052 DOI: 10.2144/000113703] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Accepted: 05/16/2011] [Indexed: 11/23/2022] Open
Abstract
Fluorescent imaging of cytoskeletal structures permits studies of both organization within the cell and dynamic reorganization of the cytoskeleton itself. Traditional fluorescent labels of microtubules, part of the cytoskeleton, have been used to study microtubule localization, structure, and dynamics, both in vivo and in vitro. However, shortcomings of existing labels make imaging of microtubules with high precision light microscopy difficult. In this paper, we report a new fluorescent labeling technique for microtubules, which involves a GTP analog modified with a bright, organic fluorophore (TAMRA, Cy3, or Cy5). This fluorescent GTP binds to a specific site, the exchangeable site, on tubulin in solution with a dissociation constant of 1.0±0.4 µM. Furthermore, the label becomes permanently incorporated into the microtubule lattice once tubulin polymerizes. We show that this label is usable as a single molecule fluorescence probe with nanometer precision and expect it to be useful for modern subdiffraction optical microscopy of microtubules and the cytoskeleton.
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Sakumi K, Abolhassani N, Behmanesh M, Iyama T, Tsuchimoto D, Nakabeppu Y. ITPA protein, an enzyme that eliminates deaminated purine nucleoside triphosphates in cells. Mutat Res 2010; 703:43-50. [PMID: 20601097 DOI: 10.1016/j.mrgentox.2010.06.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Accepted: 06/13/2010] [Indexed: 12/14/2022]
Abstract
Inosine triphosphate pyrophosphatase (ITPA protein) (EC 3.6.1.19) hydrolyzes deaminated purine nucleoside triphosphates, such as ITP and dITP, to their corresponding purine nucleoside monophosphate and pyrophosphate. In mammals, this enzyme is encoded by the Itpa gene. Using the Itpa gene-disrupted mouse as a model, we have elucidated the biological significance of the ITPA protein and its substrates, ITP and dITP. Itpa(-/-) mice exhibited peri- or post-natal lethality dependent on the genetic background. The heart of the Itpa(-/-) mouse was found to be structurally and functionally abnormal. Significantly higher levels of deoxyinosine and inosine were detected in nuclear DNA and RNA prepared from Itpa(-/-) embryos compared to wild type embryos. In addition, an accumulation of ITP was observed in the erythrocytes of Itpa(-/-) mice. We found that Itpa(-/-) primary mouse embryonic fibroblasts (MEFs), which have no detectable ability to generate IMP from ITP in whole cell extracts, exhibited a prolonged population-doubling time, increased chromosome abnormalities and accumulation of single-strand breaks in their nuclear DNA, in comparison to primary MEFs prepared from wild type embryos. These results revealed that (1) ITP and dITP are spontaneously produced in vivo and (2) accumulation of ITP and dITP is responsible for the harmful effects observed in the Itpa(-/-) mouse. In addition to its effect as the precursor nucleotide for RNA transcription, ITP has the potential to influence the activity of ATP/GTP-binding proteins. The biological significance of ITP and dITP in the nucleotide pool remains to be elucidated.
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Affiliation(s)
- Kunihiko Sakumi
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
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10
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Functional significance may underlie the taxonomic utility of single amino acid substitutions in conserved proteins. J Mol Evol 2010; 70:395-402. [PMID: 20386893 PMCID: PMC2874023 DOI: 10.1007/s00239-010-9338-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We hypothesized that some amino acid substitutions in conserved proteins that are strongly fixed by critical functional roles would show lineage-specific distributions. As an example of an archetypal conserved eukaryotic protein we considered the active site of β-tubulin. Our analysis identified one amino acid substitution—β-tubulin F224—which was highly lineage specific. Investigation of β-tubulin for other phylogenetically restricted amino acids identified several with apparent specificity for well-defined phylogenetic groups. Intriguingly, none showed specificity for “supergroups” other than the unikonts. To understand why, we analysed the β-tubulin Neighbor-Net and demonstrated a fundamental division between core β-tubulins (plant-like) and divergent β-tubulins (animal and fungal). F224 was almost completely restricted to the core β-tubulins, while divergent β-tubulins possessed Y224. Thus, our specific example offers insight into the restrictions associated with the co-evolution of β-tubulin during the radiation of eukaryotes, underlining a fundamental dichotomy between F-type, core β-tubulins and Y-type, divergent β-tubulins. More broadly our study provides proof of principle for the taxonomic utility of critical amino acids in the active sites of conserved proteins.
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Läppchen T, Pinas VA, Hartog AF, Koomen GJ, Schaffner-Barbero C, Andreu JM, Trambaiolo D, Löwe J, Juhem A, Popov AV, den Blaauwen T. Probing FtsZ and tubulin with C8-substituted GTP analogs reveals differences in their nucleotide binding sites. ACTA ACUST UNITED AC 2008; 15:189-99. [PMID: 18291323 DOI: 10.1016/j.chembiol.2007.12.013] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2007] [Revised: 12/21/2007] [Accepted: 12/28/2007] [Indexed: 11/25/2022]
Abstract
The cytoskeletal proteins, FtsZ and tubulin, play a pivotal role in prokaryotic cell division and eukaryotic chromosome segregation, respectively. Selective inhibitors of the GTP-dependent polymerization of FtsZ could constitute a new class of antibiotics, while several inhibitors of tubulin are widely used in antiproliferative therapy. In this work, we set out to identify selective inhibitors of FtsZ based on the structure of its natural ligand, GTP. We found that GTP analogs with small hydrophobic substituents at C8 of the nucleobase efficiently inhibit FtsZ polymerization, whereas they have an opposite effect on the polymerization of tubulin. The inhibitory activity of the GTP analogs on FtsZ polymerization allowed us to crystallize FtsZ in complex with C8-morpholino-GTP, revealing the binding mode of a GTP derivative containing a nonmodified triphosphate chain.
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Affiliation(s)
- Tilman Läppchen
- Van 't Hoff Institute for Molecular Sciences, Bioorganic Chemistry, University of Amsterdam, Nieuwe Achtergracht 129, 1018 WS Amsterdam, The Netherlands
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12
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Muraoka M, Sakai H. Effects of purinenucleotide analogues on microtubule assembly. Cell Struct Funct 2004; 24:305-12. [PMID: 15216887 DOI: 10.1247/csf.24.305] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
This minireview summarizes the syntheses of various purinenucleotide analogues and their effects on microtubule (Mt) assembly. 27 analogues were so far synthesized and, together with 3 analogues commercially available (ITP, XTP and dGTP), their effects on Microtubule assembly were investigated. The positions C2, C6, C8, and ribose moiety of purine nucleotides were modified or substituted. It was found that the microenvironments of the purine base and ribose moiety are important for the nucleotides to support Mt assembly. Introduction of amino group into position C2 of ATP, formation of 2-amino ATP, caused Mt assembly substantially. 2-Amino deoxy ATP and deoxy GTP are more potent than GTP in supporting assembly. The introduction of reactive thiol group into C6 (6-SH-GTP) largely reduces the activity of the analogue to support assembly. However, sequestering reactivity of the thiol group by association with methyl group largely recovers the ability of the analogue to promote assembly. Free rotation of the glycosidic linkage was found to be also innevitable in promoting assembly, as the introduction of sulfur atom between C8 of the purine base and C2' of the ribose moiety (formation of 8,2'-S-cyclo purine nucleotides) caused total inhibition. Purinenucleoside triphosphate supports assembly better than GTP but the deoxy-type analogues are totally inhibitory. 2-Amino-8-hydroxy ATP and other analogues support assembly much better than does GTP. However, their diphosphate analogues are totally incapable of supporting assembly. Introduction of a bulky fluorescent probes into C3' can be made to visualize the fluorescent signal in assembled Mts. Together with the suggestions proposed from electron chrystallography of zinc-induced tubulin sheets, interactions of the purine base and ribose moieties with surrounding amino acid residues are discussed.
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Affiliation(s)
- M Muraoka
- Department of Chemical and Biological Sciences, Faculty of Science, Japan Women's University, Bunkyo-ku, Tokyo 112-8681, Japan
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Sakai H, Maruno A, Sugawara N, Takahashi K, Hoshi C, Nakamura A, Nakamura R, Shinozaki N, Sato M, Osumi M. Nucleation of Astral-shaped Microtubules from Latex Beads Conjugated with MTOG Proteins. Zoolog Sci 2000; 17:609-15. [DOI: 10.2108/zsj.17.609] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/1999] [Accepted: 11/11/1999] [Indexed: 11/17/2022]
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