Enhancement of stress tolerance in transgenic tobacco plants constitutively expressing AtIpk2β, an inositol polyphosphate 6-/3-kinase from Arabidopsis thaliana

Inositol phosphates (IPs) and their turnover products have been implicated to play important roles in stress signaling in eukaryotic cells. In higher plants genes encoding inositol polyphosphate kinases have been identified previously, but their physiological functions have not been fully resolved. Here we expressed Arabidopsis inositol polyphosphate 6-/3-kinase (AtIpk2β) in two heterologous systems, i.e. the yeast Saccharomycescerevisiae and in tobacco (Nicotiana tabacum), and tested the effect on abiotic stress tolerance. Expression of AtIpk2β rescued the salt-, osmotic- and temperature-sensitive growth defects of a yeast mutant strain (arg82Δ) that lacks inositol polyphosphate multikinase activity encoded by the ARG82/IPK2 gene. Transgenic tobacco plants constitutively expressing AtIpk2β under the control of the Cauliflower Mosaic Virus 35S promoter were generated and found to exhibit improved tolerance to diverse abiotic stresses when compared to wild type plants. Expression patterns of various stress responsive genes were enhanced, and the activities of anti-oxidative enzymes were elevated in transgenic plants, suggesting a possible involvement of AtIpk2β in plant stress responses

Clonage moléculaire des isoformes B et C de l'inositol 1, 4, 5-trisphosphate 3-kinase et influence de leur surexpression sur la réponse calcique

Doctorat en Sciencesinfo:eu-repo/semantics/nonPublishe

Clonage moléculaire des isoformes B et C de l'inositol 1, 4, 5-trisphosphate 3-kinase et influence de leur surexpression sur la réponse calcique

Doctorat en Sciencesinfo:eu-repo/semantics/nonPublishe

Inositol 1, 4, 5-trisphosphate 3-kinase and 5-phosphatase

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Inositol 1, 4, 5-trisphosphate 3-kinase and 5-phosphatase

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Identification and subcellular distribution of endogenous Ins(1,4,5)P3 3-kinase B in mouse tissues

Inositol 1,4,5-trisphosphate 3-kinase (IP3-3K) catalyses the phosphorylation of inositol 1,4,5-trisphosphate to inositol 1,3,4,5-tetrakisphosphate. cDNAs encoding three mammalian isoforms have been reported and referred to as IP3-3KA, IP3-3KB, and IP3-3KC. IP3-3KB is particularly sensitive to proteolysis at the N-terminus, a mechanism known to generate active fragments of lower molecular mass. Endogenous IP3-3KB has therefore not been formally identified in tissues. We have probed a series of murine tissues with an antibody directed against the C-terminus of IP3-3KB and used IP3-3KB deficient mouse tissues as negative controls. IP3-3KB was shown to be particularly well expressed in brain, lung, and thymus with molecular masses of 110–120 kDa. The identification of the native IP3-3KB by Western blotting for the first time will facilitate further studies of regulation of its activity by specific proteases and/or phosphorylationARC - Actions de Recherche Concertées; IAP - Interuniversity Attraction Pole

Calcium-Calmodulin-dependent protein kinase II and protein kinase C-mediated phosphorylation and activation of D-myo-inositol 1,4,5-trisphosphate 3-kinase B in astrocytes

D-myo-Inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) 3-kinase catalyzes the production of D-myo-inositol 1,3,4,5-tetrakisphosphate from the second messenger Ins (1,4,5)P3. Transient and okadaic acid-sensitive activation of Ins(1,4,5)P3 3-kinase by 8-10-fold is observed in homogenates prepared from rat cortical astrocytes after incubation with either carbachol or UTP. 12-O-Tetradecanoylphorbol-13-acetate provokes the activation of Ins(1,4,5)P3 3-kinase by 2-fold in both cell systems. The kinase was purified by calmodulin-Sepharose from the two cell systems. Enzyme activity corresponding to the silver-stained 88-kDa protein could be regenerated after SDS-polyacrylamide gel electrophoresis. Antibodies to two distinct peptides chosen in the primary structure of human Ins(1,4,5)P3 3-kinase B recognized the astrocytic native isoform. In [32P]orthophosphate-preincubated cells, a major phosphorylated 88-kDa enzyme could be purified and identified in cells in response to receptor activation or 12-O-tetradecanoylphorbol-13-acetate treatment. Calmodulin kinase II inhibitors (i.e. KN-93 and KN-62) and a protein kinase C inhibitor (i.e. calphostin C) prevented the phosphorylation of the 88-kDa isoenzyme. In addition to enzyme activation, a redistribution of Ins(1,4,5)P3 3-kinase from soluble to particulate fraction of astrocytes was observed. In vitro phosphorylation of the purified enzyme by calmodulin kinase II and protein kinase C added together resulted in a maximal 60-70-fold activation.Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe

Inositol polyphosphate kinase activity of Arg82/ArgRIII is not required for the regulation of the arginine metabolism in yeast

Arg82, a nuclear regulator of diverse cellular processes in yeast, is an inositol polyphosphate kinase. Some defects such as the regulation of arginine metabolism observed in an arg82Δ, result from a lack of Mcm1 and Arg80 stability. We show here that neither the kinase activity of Arg82 nor inositol phosphates are required for the control of arginine metabolism. Arg82 mutations keeping kinase active affect the expression of arginine genes, whereas mutations in the kinase domain do not impair this metabolic control. Copyright (C) 2000 Federation of European Biochemical Societies.Journal ArticleResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe

Cloning and expression of a full-length cDNA encoding human inositol 1,4,5-trisphosphate 3-kinase B

Inositol 1,4,5-trisphosphate (InsP(3)) 3-kinase catalyzes the phosphorylation of InsP(3) to inositol 1,3,4,5-tetrakisphosphate (InsP(4)). cDNAs encoding three isoenzymes of InsP(3) 3-kinase (3-kinases A, B, and C) have been previously reported; however, a demonstrably full-length cDNA encoding human InsP(3) 3-kinase B was still lacking. Here we report the cloning of a full-length 2841-bp cDNA encoding human InsP(3) 3-kinase B. Northern blot analysis shows the presence of an ubiquitous transcript of approximately 7.2 kb in a large number of human tissues. InsP(3) 3-kinase activity measured in COS-7 cells transfected with InsP(3) 3-kinase B shows an activity that was 8-fold increased upon the addition of Ca(2+)/calmodulin in the assay mixture.Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe

Cloning and expression of a cDNA encoding human inositol 1,4,5-trisphosphate 3-kinase C

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