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.
Original language | English |
---|---|
Pages (from-to) | 2621–2638 |
Number of pages | 18 |
Journal | Biochemical Journal |
Volume | 477 |
Issue number | 14 |
DOIs | |
Publication status | Published - 24 Jul 2020 |
Keywords
- IPK1
- ITPK1
- diphosphoinositol phosphates
- energy charge
- phosphate homeostasis
Profiles
-
Charles Brearley
- School of Biological Sciences - Professor of Biochemistry
- Molecular Microbiology - Member
- Plant Sciences - Member
Person: Research Group Member, Academic, Teaching & Research
-
Andrew Hemmings
- School of Biological Sciences - Professor of Structural Biology
- School of Chemistry, Pharmacy and Pharmacology - Professor
- Centre for Molecular and Structural Biochemistry - Member
- Chemistry of Life Processes - Member
- Molecular Microbiology - Member
- Plant Sciences - Member
Person: Research Group Member, Research Centre Member, Academic, Teaching & Research