scholarly journals Metabolic evidence for the order of addition of individual phosphate esters in the myo-inositol moiety of inositol hexakisphosphate in the duckweed Spirodela polyrhiza L

1996 ◽  
Vol 314 (1) ◽  
pp. 227-233 ◽  
Author(s):  
Charles A. BREARLEY ◽  
David E. HANKE
Keyword(s):  
Inositol Phosphates ◽  
Preceding Paper ◽  
Phosphate Esters ◽  
Equilibrium Conditions ◽  
Comprehensive Description ◽  
Monocotyledonous Plant ◽  
Spirodela Polyrhiza ◽  
Synthetic Sequence ◽  
Massive Accumulation ◽  
Inositol Ring

The aquatic monocotyledonous plant Spirodela polyrhiza was labelled with [32P]Pi for short periods under non-equilibrium conditions. An InsP6 fraction was obtained and dissected by using enantiospecific (enzymic) and non-enantiospecific (chemical) means to determine the relative labelling of individual phosphate substituents on the inositol ring of InsP6. Phosphates in positions D-1, -2, -3, -4, -5 and -6 contained approx. 21%, 32–39%, 9–10%, 14–16%, 19–23% and 16–18% of the label respectively. We conclude from the foregoing, together with identities [described in the preceding paper, Brearley and Hanke (1996) Biochem. J. 314, 215–225] of inositol phosphates found in this plant at a developmental stage associated with massive accumulation of InsP6, that synthesis of InsP6 from myo-inositol proceeds according to the sequence Ins3P → Ins(3,4)P2 → Ins(3,4,6)P3 → Ins(3,4,5,6)P4 → Ins(1,3,4,5,6)P5 → Ins P6 in Spirodela polyrhiza. These results represent the first description of the synthetic sequence to InsP6 in the plant kingdom and the only comprehensive description of endogenous inositol phosphates in any plant tissue. The sequence described differs from that reported in the slime mould Dictyostelium discoideum.

scholarly journals Inositol phosphates in the duckweed Spirodela polyrhiza L

1996 ◽  
Vol 314 (1) ◽  
pp. 215-225 ◽  
Author(s):  
Charles A. BREARLEY ◽  
David E. HANKE
Keyword(s):  
Developmental Stage ◽  
Higher Plants ◽  
Inositol Phosphates ◽  
Second Messengers ◽  
Direct Link ◽  
Spirodela Polyrhiza ◽  
Massive Accumulation

We have undertaken an analysis of the inositol phosphates of Spirodela polyrhiza at a developmental stage when massive accumulation of InsP6 indicates that a large net synthesis is occurring. We have identified Ins3P, Ins(1,4)P2, Ins(3,4)P2 and possibly Ins(4,6)P2, Ins(3,4,6)P3, Ins(3,4,5,6)P4, Ins(1,3,4,5,6)P5, D- and/or L-Ins(1,2,4,5,6)P5 and InsP6 and revealed the likely presence of a second InsP3 with chromatographic properties similar to Ins(1,4,5)P3. The higher inositol phosphates identified show no obvious direct link to pathways of metabolism of second messengers purported to operate in higher plants, nor do they resemble the immediate products of plant phytase action on InsP6.

Phosphate, inositol and polyphosphates

2016 ◽  
Vol 44 (1) ◽  
pp. 253-259 ◽  
Author(s):  
Thomas M. Livermore ◽  
Cristina Azevedo ◽  
Bernadett Kolozsvari ◽  
Miranda S.C. Wilson ◽  
Adolfo Saiardi
Keyword(s):  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
High Energy ◽  
Inorganic Polyphosphate ◽  
Covalent Bonds ◽  
Polymeric Form ◽  
Phosphodiester Bond ◽  
Signalling Molecules ◽  
Inositol Ring ◽  
Phosphate Groups

Eukaryotic cells have ubiquitously utilized the myo-inositol backbone to generate a diverse array of signalling molecules. This is achieved by arranging phosphate groups around the six-carbon inositol ring. There is virtually no biological process that does not take advantage of the uniquely variable architecture of phosphorylated inositol. In inositol biology, phosphates are able to form three distinct covalent bonds: phosphoester, phosphodiester and phosphoanhydride bonds, with each providing different properties. The phosphoester bond links phosphate groups to the inositol ring, the variable arrangement of which forms the basis of the signalling capacity of the inositol phosphates. Phosphate groups can also form the structural bridge between myo-inositol and diacylglycerol through the phosphodiester bond. The resulting lipid-bound inositol phosphates, or phosphoinositides, further expand the signalling potential of this family of molecules. Finally, inositol is also notable for its ability to host more phosphates than it has carbons. These unusual organic molecules are commonly referred to as the inositol pyrophosphates (PP-IPs), due to the presence of high-energy phosphoanhydride bonds (pyro- or diphospho-). PP-IPs themselves constitute a varied family of molecules with one or more pyrophosphate moiety/ies located around the inositol. Considering the relationship between phosphate and inositol, it is no surprise that members of the inositol phosphate family also regulate cellular phosphate homoeostasis. Notably, the PP-IPs play a fundamental role in controlling the metabolism of the ancient polymeric form of phosphate, inorganic polyphosphate (polyP). Here we explore the intimate links between phosphate, inositol phosphates and polyP, speculating on the evolution of these relationships.

scholarly journals Formation of methylphosphoryl inositol phosphates by extractions that employ methanol

1988 ◽  
Vol 253 (3) ◽  
pp. 703-710 ◽  
Author(s):  
J E Brown ◽  
M Rudnick ◽  
A J Letcher ◽  
R F Irvine
Keyword(s):  
Alkaline Phosphatase ◽  
Methanol Extract ◽  
Inositol Phosphates ◽  
Red Cell ◽  
Unknown Compound ◽  
Methyl Group ◽  
Phosphatidylinositol Bisphosphate ◽  
Inositol 1,4,5 Trisphosphate ◽  
Inositol Ring ◽  
Retinal Volume

Fixatives that contain methanol extract an unknown compound from several tissues including the retinas of squid (Loligo). We have determined that the compound probably contains (1) a myo-inositol ring that is phosphorylated in more than one position (including at the 5-hydroxyl), (2) a charged moiety that is not susceptible to alkaline phosphatase, and (3) a methyl group. We have found that the compound can be made by treating either phosphatidylinositol bisphosphate or human red cell ghosts with acidic methanol. We have confirmed the observation of Lips, Bross & Majerus [Proc. Natl. Acad. Sci. U.S.A. 85, 88-92] that the compound also can be made by methanolysis of inositol (cyclic 1:2,4,5)trisphosphate; however, we have not found inositol (cyclic 1:2,4,5)trisphosphate in either stimulated or unstimulated squid retinas. We tentatively identify the compound as (1-methylphosphoryl)inositol 4,5-bisphosphate formed by methanolysis of phosphatidylinositol 4,5-bisphosphate. By using this methanolysis to incorporate label from [14C]methanol, we have estimated the mass of inositol 1,4,5-trisphosphate in squid retinas to be approx. 30 mumol/l of retinal volume.

Mutations in genes controlling the biosynthesis and accumulation of inositol phosphates in seeds

2010 ◽  
Vol 38 (2) ◽  
pp. 689-694 ◽  
Author(s):  
Søren K. Rasmussen ◽  
Christina Rønn Ingvardsen ◽  
Anna Maria Torp
Keyword(s):  
Phytic Acid ◽  
Biosynthetic Pathway ◽  
Molecular Breeding ◽  
Inositol Phosphates ◽  
Plant Seeds ◽  
Protein Storage Vacuoles ◽  
Insertion Elements ◽  
Induced Mutagenesis ◽  
Inositol Ring ◽  
Days After Anthesis

Most of the phosphorus in the resting seed is stored inside protein storage vacuoles as PA (phytic acid; InsP6). The biosynthesis and accumulation of PA can be detected beginning from a few days after anthesis and seem to continue during seed development until maturation. The first step in PA biosynthesis is the formation of Ins3P by conversion of glucose 6-phosphate. This is then followed by a sequential and ordered phosphorylation of the remaining five positions of the inositol ring by a number of kinases, resulting in PA. Identification of low-PA mutants in cereals, legumes and Arabidopsis is instrumental for resolving the biosynthetic pathway and identification of genes controlling the accumulation of PA. Mutations in seven genes involved in the metabolism of PA have been identified and characterized among five plant species using induced mutagenesis and insertion elements. Understanding the biosynthetic pathway and genes controlling the accumulation of PA in plant seeds and how PA may balance the free phosphate is of importance for molecular breeding of crop plants, particularly cereals and legumes.

scholarly journals Rapid accumulation of inositol trisphosphate reveals that agonists hydrolyse polyphosphoinositides instead of phosphatidylinositol

1983 ◽  
Vol 212 (3) ◽  
pp. 849-858 ◽  
Author(s):  
M J Berridge
Keyword(s):  
Inositol Phosphates ◽  
Second Messengers ◽  
Inositol Phospholipids ◽  
Hormone Sensitive ◽  
High Level ◽  
Phosphatidylinositol 4 ◽  
Energy Dependent ◽  
Hydrolysis Of ◽  
Massive Accumulation ◽  
Primary Action

The agonist-dependent hydrolysis of inositol phospholipids was investigated by studying the breakdown of prelabelled lipid or by measuring the accumulation of inositol phosphates. Stimulation of insect salivary glands with 5-hydroxytryptamine for 6 min provoked a rapid disappearance of [3H]phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] and [3H]phosphatidylinositol 4-phosphate (PtdIns4P) but had no effect on the level of [3H]phosphatidylinositol (PtdIns). The breakdown of PtdIns(4,5)P2 was associated with a very rapid release of inositol 1,4,5-trisphosphate [Ins(1,4,5)P3], which reached a peak 5 1/2 times that of the resting level after 5 s of stimulation. This high level was not maintained but declined to a lower level, perhaps reflecting the disappearance of PtdIns(4,5)P2. 5-Hydroxytryptamine also induced a rapid and massive accumulation of inositol 1,4-bisphosphate [Ins(1,4)P2]. The fact that these increases in Ins(1,4,5)P3 and Ins(1,4)P2 precede in time any increase in the level of inositol 1-phosphate or inositol provides a clear indication that the primary action of 5-hydroxytryptamine is to stimulate the hydrolysis of PtdIns(4,5)P2 to yield diacylglycerol and Ins(1,4,5)P3. The latter is then hydrolysed by a series of phosphomonoesterases to produce Ins(1,4)P2, Ins1P and finally inositol. The very rapid agonist-dependent increases in Ins(1,4,5)P3 and Ins(1,4)P2 suggests that they could function as second messengers, perhaps to control the release of calcium from internal pools. The PtdIns(4,5)P2 that is used by the receptor mechanism represents a small hormone-sensitive pool that must be constantly replenished by phosphorylation of PtdIns. Small changes in the size of this small energy-dependent pool of polyphosphoinositide will alter the effectiveness of the receptor mechanism and could account for phenomena such as desensitization and super-sensitivity.

scholarly journals Inositol phosphates and phosphoinositides activate insulin-degrading enzyme, while phosphoinositides also mediate binding to endosomes

2017 ◽  
Vol 114 (14) ◽  
pp. E2826-E2835 ◽  
Author(s):  
Eun Suk Song ◽  
HyeIn Jang ◽  
Hou-Fu Guo ◽  
Maria A. Juliano ◽  
Luiz Juliano ◽  
...  
Keyword(s):  
Bioactive Peptides ◽  
Inositol Phosphates ◽  
Amyloid Β ◽  
Insulin Degrading Enzyme ◽  
Degrading Enzyme ◽  
Positional Effects ◽  
Endogenous Modulators ◽  
Inositol Ring ◽  
Phosphate Groups ◽  
Physiological Substrates

Insulin-degrading enzyme (IDE) hydrolyzes bioactive peptides, including insulin, amylin, and the amyloid β peptides. Polyanions activate IDE toward some substrates, yet an endogenous polyanion activator has not yet been identified. Here we report that inositol phosphates (InsPs) and phosphatdidylinositol phosphates (PtdInsPs) serve as activators of IDE. InsPs and PtdInsPs interact with the polyanion-binding site located on an inner chamber wall of the enzyme. InsPs activate IDE by up to ∼95-fold, affecting primarily Vmax. The extent of activation and binding affinity correlate with the number of phosphate groups on the inositol ring, with phosphate positional effects observed. IDE binds PtdInsPs from solution, immobilized on membranes, or presented in liposomes. Interaction with PtdInsPs, likely PtdIns(3)P, plays a role in localizing IDE to endosomes, where the enzyme reportedly encounters physiological substrates. Thus, InsPs and PtdInsPs can serve as endogenous modulators of IDE activity, as well as regulators of its intracellular spatial distribution.

scholarly journals The interrelationships of the inositol phosphates formed in vasopressin-stimulated WRK-1 rat mammary tumour cells

1992 ◽  
Vol 286 (2) ◽  
pp. 469-474 ◽  
Author(s):  
C J Barker ◽  
N S Wong ◽  
S M Maccallum ◽  
P A Hunt ◽  
R H Michell ◽  
...  
Keyword(s):  
Structural Characterization ◽  
Inositol Phosphates ◽  
Preceding Paper ◽  
Second Messenger ◽  
Receptor Activation ◽  
Temporal Sequence ◽  
Mammary Tumour ◽  
Double Labelling ◽  
Inositol Monophosphatase ◽  
Gradual Accumulation

1. Temporal changes in the levels of many inositol phosphates, whose structural characterization is presented in the preceding paper [Wong, Barker, Morris, Craxton, Kirk & Michell (1991) Biochem. J. 286, 459-468], have been monitored in vasopressin-stimulated WRK-1 cells. 2. Upon stimulation, Ins(1,4,5)P3 accumulated within 1 s, consistent with its role as a rapidly acting second messenger produced by receptor activation of phosphoinositidase C. Ins(1,4)P2 and Ins(1,3,4,5)P4, both of which are immediate products of Ins(1,4,5)P3 metabolism, also accumulated quickly. Ins4P, Ins(1,3,4)P3, Ins(3,4)P2, Ins(1,3)P2, Ins1P and Ins3P, which are intermediates in the metabolism of Ins(1,4)P2 and Ins(1,3,4,5)P4 to inositol, accumulated after seconds or within a few minutes, and in a temporal sequence consistent with their known metabolic interrelationships. 3. The stimulated accumulation of Ins(1,3,4,6)P4 was delayed, as expected if it is formed by phosphorylation of Ins(1,3,4)P3. 4. Ins(3,4,5,6)P4 accumulated 2-3-fold in a few minutes, and mainly before Ins(1,3,4,6)P4. 5. Using a [3H]-/[14C]-inositol double-labelling protocol, we obtained evidence that all of the compounds that accumulated upon stimulation, except Ins(3,4,5,6)P4, originated from lipid-derived Ins(1,4,5)P3, but that the newly formed Ins(3,4,5,6)P4 came from a different source. 6. There were no consistent changes in the levels of Ins(1,3,4,5,6)P5 and InsP6 during stimulation. 7. Alongside the gradual accumulation of Ins(1:2-cyclic,4,5)P3 during stimulation [Wong, Barker, Shears, Kirk & Michell (1988) Biochem. J. 252, 1-5], there was an accumulation of Ins(1:2-cyclic,4)P2 and Ins(1:2-cyclic)P, probably as either minor side products of phosphoinositidase C action or metabolites of Ins(1:2-cyclic,4,5)P3. 8. When Li+ was present during stimulation, it redirected the dephosphorylation pathways downstream of Ins(1,4,5)P3 in the manner expected from its inhibition of inositol monophosphatase and Ins(1,4)P2/Ins(1,3,4)P3 1-phosphatase: there were marked increases in the accumulation of Ins(1,4)P2 and Ins(1,3,4)P3 and of monophosphates. Moreover, Li+ shifted the Ins1P/Ins3P balance in favour of Ins1P, thus demonstrating redirection of the metabolism of the accumulated Ins(1,3,4)P3 towards Ins(1,3)P2 rather than Ins(3,4)P2.

scholarly journals Inositol phosphate metabolism in bradykinin-stimulated human A431 carcinoma cells. Relationship to calcium signalling

1987 ◽  
Vol 244 (1) ◽  
pp. 129-135 ◽  
Author(s):  
B C Tilly ◽  
P A van Paridon ◽  
I Verlaan ◽  
K W A Wirtz ◽  
S W de Laat ◽  
...  
Keyword(s):  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Second Messengers ◽  
Calcium Signalling ◽  
Carcinoma Cells ◽  
A431 Cells ◽  
Inositol Phosphate Metabolism ◽  
Transient Rise ◽  
Lag Period ◽  
Massive Accumulation

Stimulation of human A431 epidermoid carcinoma cells by bradykinin causes a very rapid release of inositol phosphates and a transient rise in cytoplasmic free Ca2+ concentration ([Ca2+]i). Bradykinin-induced inositol phosphate formation is half-maximal at a concentration of 4 nM and is not affected by pertussis toxin. H.p.l.c. analysis of the various inositol phosphates shows an immediate but transient accumulation of inositol 1,4,5-trisphosphate [Ins(1,4,5)P3], which reaches a peak value of approx. 10 times the basal level within 15 s and slightly precedes the rise in [Ca2+]i, both parameters changing in parallel. After a lag period, bradykinin also induces a massive accumulation of Ins(1,3,4)P3 and inositol 1,3,4,5-tetrakisphosphate [Ins(1,3,4,5)P4]. Our data support the view that part of the newly formed Ins(1,4,5)P3 is converted into Ins(1,3,4)P3 phosphorylation/dephosphorylation with Ins(1,3,4,5)P4 as intermediate. Furthermore, A431 cells were found to contain strikingly high basal levels of two other inositol phosphates, presumably inositol pentakisphosphate (InsP5) and inositol hexakisphosphate (InsP6), representing more than 50% of the total 3H radioactivity incorporated into inositol phosphates. The presumptive InsP5 and InsP6 are only slightly affected by bradykinin. Although Ins(1,3,4)P3 and InsP4 could function as second messengers, our results suggest that, unlike Ins(1,4,5)P3, neither Ins(1,3,4)P3 nor InsP4 are involved in Ca2+ mobilization.

scholarly journals Metabolic evidence for PtdIns(4,5)P2-directed phospholipase C in permeabilized plant protoplasts

1997 ◽  
Vol 324 (1) ◽  
pp. 123-131 ◽  
Author(s):  
Charles A. BREARLEY ◽  
Paroo N. PARMAR ◽  
David E. HANKE
Keyword(s):  
Phospholipase C ◽  
Mammalian Cells ◽  
Higher Plants ◽  
Inositol Phosphates ◽  
Physiological Role ◽  
Phosphate Esters ◽  
Plant Protoplasts ◽  
Genes Encoding ◽  
Alternative Routes

Comparison of the sequences of the genes encoding phospholipase C (PLC) which have been cloned to date in plants with their mammalian counterparts suggests that plant PLC is similar to PLCδ of mammalian cells. The physiological role and mechanism of activation of PLCδ is unclear. It has recently been shown that Ins(1,4,5)P3 may not solely be the product of PtdIns(4,5)P2-directed PLC activity. Enzyme activities capable of producing Ins(1,4,5)P3 from endogenous inositol phosphates are present in Dictyostelium and also in rat liver. Significantly it has not been directly determined whether Ins(1,4,5)P3 present in higher plants is the product of a PtdIns(4,5)P2-directed PLC activity. Therefore we have developed an experimental strategy for the identification of d-Ins(1,4,5)P3 in higher plants. By the use of a short-term non-equilibrium labelling strategy in permeabilized plant protoplasts, coupled to the use of a ‘metabolic trap‘ to prevent degradation of [32P]Ins(1,4,5)P3, we were able to determine the distribution of 32P in individual phosphate esters of Ins(1,4,5)P3. The [32]Ins(1,4,5)P3 identified showed the same distribution of label in individual phosphate esters as that of [32P]PtdIns(4,5)P2 isolated from the same tissue. We thus provide in vivo evidence for the action of a PtdIns(4,5)P2-directed PLC activity in plant cells which is responsible for the production of Ins(1,4,5)P3 observed here. This observation does not, however, exclude the possibility that in other cells or under different conditions Ins(1,4,5)P3 can be generated by alternative routes.

Effect of several germination conditions on total P, phytate P, phytase, acid phosphatase activities and inositol phosphate esters in spring and winter wheat

2003 ◽  
Vol 141 (3-4) ◽  
pp. 313-321 ◽  
Author(s):  
C. CENTENO ◽  
A. VIVEROS ◽  
A. BRENES ◽  
A. LOZANO ◽  
C. DE LA CUADRA
Keyword(s):  
Acid Phosphatase ◽  
Winter Wheat ◽  
Phosphorus Content ◽  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Phosphate Esters ◽  
Soaking Time ◽  
Phytate Phosphorus ◽  
Germination Process ◽  
Total P

Changes in the wheat phosphatases (phytase-Phy and acid phosphatase-AcPh) and the degradation of their substrates (inositol phosphates esters) during seed germination have been examined in two studies. Germinated grains with high phytate degrading enzymes are of potential interest in the improvement of phosphorus availability in monogastric animals. In the first study, the seeds were soaked for 1 and 14 h and germinated for 3 and 5 days with and without the addition of gibberellic acid (GA3). In the second study, the seeds were soaked for 1 h and germinated for 1, 3 and 5 days with GA3. Phytase (up to 1800 and 1573 U/kg) and acid phosphatase (up to 13 115 and 10 154 U/g) activities and IP6 (6·96 and 7·67 mg/g), IP5 (0·40 and 0·60 mg/g) and IP4 (0·04 and 0·04 mg/g) were detected in ungerminated spring and winter wheat, respectively. The germination process caused a significant increase of Phy and AcPh activities in spring (up to 275 and 235%) and winter wheat (up to 250 and 329%) and a reduction in the phytate phosphorus content (up to 35 and 64%, respectively). Phytate phosphorus content was affected in both spring and winter wheat by the soaking time. Finally, during the course of germination, IP6 and IP5 were more rapidly degraded in winter wheat (62 and 62%) than in spring wheat (32 and 29%), and IP4 was only a short-living intermediate, which was increased during hydrolysis and degraded to IP3. In conclusion, the germination process caused a significant increase of Phy and AcPh in spring and winter wheat, which was accompanied with a significant reduction of phytate phosphorus content and an increase in the content of lower inositol phosphates.

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