<i>Arabidopsis thaliana</i> inositol 1,3,4‐trisphosphate 5/6‐kinase 4 (AtITPK4) is an outlier to a family of ATP‐grasp fold proteins from Arabidopsis

Sweetman, Dylan; Stavridou, Ioanna; Johnson, Sharon M.; Green, Phon; Caddick, Samuel E.K.; Brearley, Charles A.

doi:10.1016/j.febslet.2007.07.046

Cited by 50 publications

(98 citation statements)

References 21 publications

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“…soybean Itpks The canonical catalytic activity of all Itpk proteins is the phosphorylation of Ins(1,3,4)P 3 to both Ins(1,3,4,5)P 4 and Ins(1,3,4,6)P 4 [12,14,20,21]. We found that all four soybean Itpks phosphorylated Ins(1,3,4)P 3 ( Fig.…”

Section: Phosphorylation Of Ins(134)p 3 and Ins(3456)p 4 Bymentioning

confidence: 64%

“…Little work has been done to identify enzyme(s) that might catalyze these reactions, with the exception of a recent report showing that a racemic mixture of Ins(3,4,6)P 3 /Ins(1,4,6)P 3 was phosphorylated by the recombinant Itpk from Arabidopsis [14]. The use of a substrate mixture prevents us from knowing which of the two were phosphorylated.…”

Section: Phosphorylation Of Ins(346)p 3 By Soybean Itpksmentioning

confidence: 99%

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Metabolic and signaling properties of an Itpk gene family in Glycine max

et al. 2008

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We have cloned and characterized four Itpk genes from soybean. All four recombinant Itpk proteins showed canonical Ins(1,3,4)P 3 5/6-kinase activity, but a kinetic analysis raised questions about its biological significance. Instead, we provide evidence that one alternative biological role for soybean Itpks is to interconvert the Cl À channel inhibitor, Ins(3,4,5,6)P 4 , and its metabolic precursor, Ins(1,3,4,5,6)P 5 , within a substrate cycle. The soybean Itpks also phosphorylated Ins(3,4,6)P 3 to Ins(1,3,4,6)P 4 which was further phosphorylated to Ins(1,3,4,5,6)P 5 by soybean Ipk2. Thus, soybean Itpks may participate in an inositol lipid-independent pathway of InsP 6 synthesis.

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Section: Phosphorylation Of Ins(134)p 3 and Ins(3456)p 4 Bymentioning

confidence: 64%

Section: Phosphorylation Of Ins(346)p 3 By Soybean Itpksmentioning

confidence: 99%

Metabolic and signaling properties of an Itpk gene family in Glycine max

et al. 2008

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“…Ins(3,4,5,6)P 4 was identified in early studies of IP 6 synthesis in duckweed (50). This isomer is a substrate of plant ATP-grasp fold inositol tris/tetrakisphosphate kinases (20,(51)(52)(53), and enzymes of this class contribute to IP 6 synthesis in maize (20). We have shown using a coupled assay that Ins(3,4,5,6)P 4 and Ins(1,4,5,6)P 4 are equally effective in vitro substrates for IP 5 2-K, and we have now determined the role of Arg 130 and Arg 45 in the specification of substrate preference between enantiomers.…”

Section: Discussionmentioning

confidence: 99%

Conformational Changes in Inositol 1,3,4,5,6-Pentakisphosphate 2-Kinase upon Substrate Binding

Banos-Sanz

Sanz‐Aparicio

Whitfield

et al. 2012

Journal of Biological Chemistry

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Background: IP 5 2-K is essential for higher inositide metabolism and signaling. Results: Crystal structures and biochemical data reveal different IP 5 2-K conformational states. Conclusion: IP 5 2-K undergoes conformational changes upon nucleotide and inositide binding, with the N-lobe being essential for substrate recognition and IP 4 enantiomer selection. Significance: Understanding the determinants of enzyme function and substrate specificity will enable rational design of inhibitors.

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“…ucts, IPK1 has a dominant contribution to inositol hexakisphosphate accumulation (25). We undertook expression analysis of the effect of mutation of AtMRP5 on transcript levels of AtIPK1 and of four members of the inositol tris/tetrakisphosphate kinase family whose contribution to inositol hexakisphosphate synthesis, while undefined in Arabidopsis (34), is anticipated from studies of maize (30). The data presented in the supplementary information (supplemental Fig.…”

Section: Table 1 the Effect Of Abc Transport Inhibitors On Atmrp5-medmentioning

confidence: 99%

The Arabidopsis ATP-binding Cassette Protein AtMRP5/AtABCC5 Is a High Affinity Inositol Hexakisphosphate Transporter Involved in Guard Cell Signaling and Phytate Storage

Nagy

Grob

Weder

et al. 2009

Journal of Biological Chemistry

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Arabidopsis possesses a superfamily of ATP-binding cassette (ABC) transporters. Among these, the multidrug resistance-associated protein AtMRP5/AtABCC5 regulates stomatal aperture and controls plasma membrane anion channels of guard cells. Remarkably, despite the prominent role of AtMRP5 in conferring partial drought insensitivity upon Arabidopsis, we know little of the biochemical function of AtMRP5. Our phylogenetic analysis showed that AtMRP5 is closely related to maize MRP4, mutation of which confers a low inositol hexakisphosphate kernel phenotype. We now show that insertion mutants of AtMRP5 display a low inositol hexakisphosphate phenotype in seed tissue and that this phenotype is associated with alterations of mineral cation and phosphate status. By heterologous expression in yeast, we demonstrate that AtMRP5 encodes a specific and high affinity ATP-dependent inositol hexakisphosphate transporter that is sensitive to inhibitors of ABC transporters. Moreover, complementation of the mrp5-1 insertion mutants of Arabidopsis with the AtMRP5 cDNA driven from a guard cell-specific promoter restores the sensitivity of the mutant to abscisic acid-mediated inhibition of stomatal opening. Additionally, we show that mutation of residues of the Walker B motif prevents restoring the multiple phenotypes associated with mrp5-1. Our findings highlight a novel function of plant ABC transporters that may be relevant to other kingdoms. They also extend the signaling repertoire of this ubiquitous inositol polyphosphate signaling molecule.Guard cells form pairs of cells, which are conjoined at their ends, in the epidermis of the aerial tissues of plants. The cells surround a central pore, the stoma, through which gas exchange occurs. The principal gases exchanged are CO 2 and water vapor, and the function of the stomatal complex may be considered as the maximization of CO 2 assimilation by photosynthesis for the minimization of water loss.Guard cells and hence the aperture of the central pore are sensitive to environmental factors including light, temperature, CO 2 , and ozone (1). Stomatal closure is initiated by the drought stress hormone abscisic acid (ABA).3 The closure of stomata is a result of a loss of turgor of the delimiting guard cells as a consequence of ion efflux, predominantly Cl Ϫ and K ϩ , and metabolic conversion of organic acids into starch (2).Although the molecular identity of genes encoding the outward and inward K ϩ conductances are known for Arabidopsis thaliana (3), it remains to be demonstrated whether the recently identified SLAC protein (4, 5) encodes the S-type anion channel or is a subunit thereof.The ATP-binding cassette family of membrane proteins is among the most ubiquitous and variable group of membrane proteins and is most commonly associated with membrane transport phenomena. The substrates transported are especially diverse, and consequently a major obstacle to the interpretation of ABC transporter function, particularly pertinent in the context of guard cell function, is the identificatio...

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Arabidopsis thaliana inositol 1,3,4‐trisphosphate 5/6‐kinase 4 (AtITPK4) is an outlier to a family of ATP‐grasp fold proteins from Arabidopsis

Cited by 50 publications

References 21 publications

Metabolic and signaling properties of an Itpk gene family in Glycine max

Metabolic and signaling properties of an Itpk gene family in Glycine max

Conformational Changes in Inositol 1,3,4,5,6-Pentakisphosphate 2-Kinase upon Substrate Binding

The Arabidopsis ATP-binding Cassette Protein AtMRP5/AtABCC5 Is a High Affinity Inositol Hexakisphosphate Transporter Involved in Guard Cell Signaling and Phytate Storage

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