An ATP-responsive metabolic cassette comprised of inositol tris/tetrakisphosphate kinase 1 (ITPK1) and inositol pentakisphosphate 2-kinase (IPK1) buffers diphosphosphoinositol phosphate levels

Whitfield, Hayley, White, Gaye, Sprigg, Colleen, Riley, Andrew M., Potter, Barry V. L., Hemmings, Andrew and Brearley, Charles (2020) An ATP-responsive metabolic cassette comprised of inositol tris/tetrakisphosphate kinase 1 (ITPK1) and inositol pentakisphosphate 2-kinase (IPK1) buffers diphosphosphoinositol phosphate levels. Biochemical Journal, 477 (14). 2621–2638. ISSN 0264-6021

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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.

Item Type: Article
Uncontrolled Keywords: ipk1,itpk1,diphosphoinositol phosphates,energy charge,phosphate homeostasis,biochemistry,molecular biology,cell biology ,/dk/atira/pure/subjectarea/asjc/1300/1303
Faculty \ School: Faculty of Science > School of Biological Sciences
Faculty of Science > School of Chemistry
Related URLs:
Depositing User: LivePure Connector
Date Deposited: 07 Jul 2020 23:58
Last Modified: 03 Nov 2020 01:03
URI: https://ueaeprints.uea.ac.uk/id/eprint/75939
DOI: 10.1042/BCJ20200423

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