Arabidopsis inositol polyphosphate 6-/3-kinase is a nuclear protein that complements a yeast mutant lacking a functional ArgR-Mcm1 transcription complex.

Xia, Hui-Jun, Brearley, Charles, Elge, Stephan, Kaplan, Boaz, Fromm, Hillel and Mueller-Roeber, Bernd (2003) Arabidopsis inositol polyphosphate 6-/3-kinase is a nuclear protein that complements a yeast mutant lacking a functional ArgR-Mcm1 transcription complex. Plant Cell, 15 (2). pp. 449-463. ISSN 1532-298X

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Abstract

Inositol 1,4,5-trisphosphate 3-kinase, and more generally inositol polyphosphate kinases (Ipk), play important roles in signal transduction in animal cells; however, their functions in plant cells remain to be elucidated. Here, we report the molecular cloning of a cDNA (AtIpk2{beta}) from a higher plant, Arabidopsis. Arabidopsis AtIpk2{beta} is a 33-kD protein that exhibits weak homology (~25% identical amino acids) with Ipk proteins from animals and yeast and lacks a calmodulin binding site, as revealed by sequence analysis and calmodulin binding assays. However, recombinant AtIpk2{beta} phosphorylates inositol 1,4,5-trisphosphate to inositol 1,4,5,6-tetrakisphosphate and also converts it to inositol 1,3,4,5,6-pentakisphosphate [Ins(1,3,4,5,6)P5]. AtIpk2{beta} also phosphorylates inositol 1,3,4,5-tetrakisphosphate to Ins(1,3,4,5,6)P5. Thus, the enzyme is a D3/D6 dual-specificity inositol phosphate kinase. AtIpk2{beta} complements a yeast ARG82/IPK2 mutant lacking a functional ArgR-Mcm1 transcription complex. This complex is involved in regulating Arg metabolism–related gene expression and requires inositol polyphosphate kinase activity to function. AtIpk2{beta} was found to be located predominantly in the nucleus of plant cells, as demonstrated by immunolocalization and fusion to green fluorescent protein. RNA gel blot analysis and promoter–{beta}-glucuronidase reporter gene studies demonstrated AtIpk2{beta} gene expression in various organs tested. These data suggest a role for AtIpk2{beta} as a transcriptional control mediator in plants.

Item Type: Article
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: EPrints Services
Date Deposited: 01 Oct 2010 13:37
Last Modified: 04 May 2020 23:46
URI: https://ueaeprints.uea.ac.uk/id/eprint/611
DOI: 10.1105/tpc.006676

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