Synthesis of inositol phosphate ligands of plant hormone–receptor complexes: pathways of inositol hexakisphosphate turnover

2012 ◽  
Vol 444 (3) ◽  
pp. 601-609 ◽  
Author(s):  
David E. Hanke ◽  
Paroo N. Parmar ◽  
Samuel E. K. Caddick ◽  
Porntip Green ◽  
Charles A. Brearley
Keyword(s):  
Hormone Receptor ◽  
Plant Hormone ◽  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Leaf Tissue ◽  
Phosphate Metabolism ◽  
Inositol Hexakisphosphate ◽  
Receptor Complexes ◽  
Inositol Phosphate Metabolism ◽  
Phosphate Ligands

Reduction of phytate is a major goal of plant breeding programs to improve the nutritional quality of crops. Remarkably, except for the storage organs of crops such as barley, maize and soybean, we know little of the stereoisomeric composition of inositol phosphates in plant tissues. To investigate the metabolic origins of higher inositol phosphates in photosynthetic tissues, we have radiolabelled leaf tissue of Solanum tuberosum with myo-[2-3H]inositol, undertaken a detailed analysis of inositol phosphate stereoisomerism and permeabilized mesophyll protoplasts in media containing inositol phosphates. We describe the inositol phosphate composition of leaf tissue and identify pathways of inositol phosphate metabolism that we reveal to be common to other kingdoms. Our results identify the metabolic origins of a number of higher inositol phosphates including ones that are precursors of cofactors, or cofactors of plant hormone–receptor complexes. The present study affords alternative explanations of the effects of disruption of inositol phosphate metabolism reported in other species, and identifies different inositol phosphates from that described in photosynthetic tissue of the monocot Spirodela polyrhiza. We define the pathways of inositol hexakisphosphate turnover and shed light on the occurrence of a number of inositol phosphates identified in animals, for which metabolic origins have not been defined.

scholarly journals The quantitative spectrum of inositol phosphate metabolites in avian erythrocytes, analysed by proton n.m.r. and h.p.l.c. with direct isomer detection

1989 ◽  
Vol 264 (2) ◽  
pp. 323-333 ◽  
Author(s):  
T Radenberg ◽  
P Scholz ◽  
G Bergmann ◽  
G W Mayr
Keyword(s):  
Mammalian Cells ◽  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Detection System ◽  
Anion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Phosphate Metabolism ◽  
Qualitative And Quantitative ◽  
Inositol Phosphate Metabolism ◽  
Avian Erythrocytes

The spectrum of inositol phosphate isomers present in avian erythrocytes was investigated in qualitative and quantitative terms. Inositol phosphates were isolated in micromolar quantities from turkey blood by anion-exchange chromatography on Q-Sepharose and subjected to proton n.m.r. and h.p.l.c. analysis. We employed a h.p.l.c. technique with a novel, recently described complexometric post-column detection system, called ‘metal-dye detection’ [Mayr (1988) Biochem. J. 254, 585-591], which enabled us to identify non-radioactively labelled inositol phosphate isomers and to determine their masses. The results indicate that avian erythrocytes contain the same inositol phosphate isomers as mammalian cells. Denoted by the ‘lowest-locant rule’ [NC-IUB Recommendations (1988) Biochem. J. 258, 1-2] irrespective of true enantiomerism, these are Ins(1,4)P2, Ins(1,6)P2, Ins(1,3,4)P3, Ins(1,4,5)P3, Ins(1,3,4,5)P4, Ins(1,3,4,6)P4, Ins(1,4,5,6)P4, Ins(1,3,4,5,6)P5, and InsP6. Furthermore, we identified two inositol trisphosphate isomers hitherto not described for mammalian cells, namely Ins(1,5,6)P3 and Ins(2,4,5)P3. The possible position of these two isomers in inositol phosphate metabolism and implications resulting from absolute abundances of inositol phosphates are discussed.

scholarly journals Arabidopsis inositol phosphate kinases, IPK1 and ITPK1, constitute a metabolic pathway in maintaining phosphate homeostasis

2018 ◽  
Author(s):  
Hui-Fen Kuo ◽  
Yu-Ying Hsu ◽  
Wei-Chi Lin ◽  
Kai-Yu Chen ◽  
Teun Munnik ◽  
...  
Keyword(s):  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Phosphate Limitation ◽  
Phosphate Metabolism ◽  
Adaptive Responses ◽  
Phosphate Homeostasis ◽  
Close Link ◽  
Inositol Phosphate Metabolism ◽  
Evolutionarily Conserved ◽  
Specific Increase

SummaryEmerging studies have implicated a close link between inositol phosphate (InsP) metabolism and cellular phosphate (Pi) homeostasis in eukaryotes; however, whether a common InsPspecies is deployed as an evolutionarily conserved metabolic messenger to mediate Pisignaling remains unknown. Here, using genetics and InsPprofiling combined with Pistarvation response (PSR) analysis inArabidopsis thaliana, we showed that the kinase activity of inositol pentakisphosphate 2-kinase (IPK1), an enzyme required for phytate (inositol hexakisphosphates; InsP6) synthesis, is indispensable for maintaining Pihomeostasis under Pi-replete conditions, and inositol 1,3,4-trisphosphate 5/6-kinase 1 (ITPK1) plays an equivalent role. Although bothipk1-1anditpk1mutants exhibited decreased levels of InsP6and diphosphoinositol pentakisphosphate (PP-InsP5; InsP7), disruption of another ITPK family enzyme, ITPK4, which correspondingly caused depletion of InsP6and InsP7, did not display similar Pi-related phenotypes, which precludes these InsPspecies as effectors. Notably, the level of D/L-Ins(3,4,5,6)P4was concurrently elevated in bothipk1-1anditpk1mutants, which implies a potential role for InsP4in regulating Pihomeostasis. However, the level of D/L-Ins(3,4,5,6)P4is not responsive to Pistarvation that instead manifests a shoot-specific increase in InsP7level. This study demonstrates a more nuanced picture of intersection of InsPmetabolism and Pihomeostasis and PSR than has previously been elaborated, and additionally establishes intermediate steps to phytate biosynthesis in plant vegetative tissues.Significance StatementRegulation of phosphate homeostasis and adaptive responses to phosphate limitation is critical for plant growth and crop yield. Accumulating studies implicate inositol phosphates as regulators of phosphate homeostasis in eukaryotes; however, the relationship between inositol phosphate metabolism and phosphate signaling in plants remain elusive. This study dissected the step where inositol phosphate metabolism intersects with phosphate homeostasis regulation and phosphate starvation responses.

Differential induction of inositol phosphate metabolism by three adipokinetic hormones

1997 ◽  
Vol 130 (1-2) ◽  
pp. 131-139 ◽  
Author(s):  
Simon F Vroemen ◽  
Wil J.A Van Marrewijk ◽  
Jeroen De Meijer ◽  
Aloys Th.M Van den Broek ◽  
Dick J Van der Horst
Keyword(s):  
Inositol Phosphate ◽  
Phosphate Metabolism ◽  
Inositol Phosphate Metabolism ◽  
Differential Induction

scholarly journals Analysis of Inositol Phosphate Metabolism by Capillary Electrophoresis Electrospray Ionization Mass Spectrometry (CE-ESI-MS)

2020 ◽  
Author(s):  
Danye Qiu ◽  
Miranda S. Wilson ◽  
Verena B. Eisenbeis ◽  
Robert K. Harmel ◽  
Esther Riemer ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Capillary Electrophoresis ◽  
Electrospray Ionization ◽  
Electrospray Ionization Mass Spectrometry ◽  
Inositol Phosphate ◽  
Ionization Mass Spectrometry ◽  
Ionization Mass ◽  
Phosphate Metabolism ◽  
Esi Ms ◽  
Inositol Phosphate Metabolism

AbstractThe analysis of myo-inositol phosphates (InsPs) and myo-inositol pyrophosphates (PP-InsPs) is a daunting challenge due to the large number of possible isomers, the absence of a chromophore, the high charge density, the low abundance, and the instability of the esters and anhydrides. Given their importance in biology, an analytical approach to follow and understand this complex signaling hub is highly desirable. Here, capillary electrophoresis (CE) coupled to electrospray ionization mass spectrometry (ESI-MS) is implemented to analyze complex mixtures of InsPs and PP-InsPs with high sensitivity. Stable isotope labeled (SIL) internal standards allow for matrix-independent quantitative assignment. The method is validated in wild-type and knockout mammalian cell lines and in model organisms. SIL-CE-ESI-MS enables for the first time the accurate monitoring of InsPs and PP-InsPs arising from compartmentalized cellular synthesis pathways, by feeding cells with either [13C6]-myo-inositol or [13C6]-D-glucose. In doing so, we uncover that there must be unknown inositol synthesis pathways in mammals, highlighting the unique potential of this method to dissect inositol phosphate metabolism and signalling.

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