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Phosphate Analogue (phosphate + analogue)

Distribution by Scientific Domains
Chemistry75%

Selected Abstracts

Interaction of the Catalytic Domain of Inositol 1,4,5-Trisphosphate 3-Kinase A with Inositol Phosphate Analogues

CHEMBIOCHEM, Issue 8 2005
Alexandra Poinas Dr.
Abstract The levels of inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] in the cytoplasm are tightly regulated by two enzymes, Ins(1,4,5)P3 3-kinase and type I Ins(1,4,5)P3 5-phosphatase. The catalytic domain of Ins(1,4,5)P3 3-kinase (isoenzymes A, B and C) is restricted to approximately 275 amino acids at the C-terminal end. We were interested in understanding the catalytic mechanism of this key family of enzymes in order to exploit this in inhibitor design. We expressed the catalytic domain of rat Ins(1,4,5)P3 3-kinase A in Escherichia coli as a His- and S-tagged fusion protein. The purified enzyme was used in an Ins(1,4,5)P3 kinase assay to phosphorylate a series of inositol phosphate analogues with three or four phosphate groups. A synthetic route to D -2-deoxy-Ins(1,4,5)P3 was devised. D -2-Deoxy-Ins(1,4,5)P3 and D -3-deoxy-Ins(1,4,6)P3 were potent inhibitors of the enzyme, with IC50 values in the micromolar range. Amongst all analogues tested, only D -2-deoxy-Ins(1,4,5)P3 appears to be a good substrate of the Ins(1,4,5)P3 3-kinase. Therefore, the axial 2-hydroxy group of Ins(1,4,5)P3 is not involved in recognition of the substrate nor does it participate in the phosphorylation mechanism of Ins(1,4,5)P3. In contrast, the equatorial 3-hydroxy function must be present in that configuration for phosphorylation to occur. Our data indicate the importance of the 3-hydroxy function in the mechanism of inositol trisphosphate phosphorylation rather than in substrate binding. [source]

Involvement of a novel transcriptional activator and small RNA in post-transcriptional regulation of the glucose phosphoenolpyruvate phosphotransferase system

MOLECULAR MICROBIOLOGY, Issue 4 2004
Carin K. Vanderpool
Summary RyaA is a small non-coding RNA in Escherichia coli that was identified by its ability to bind tightly to the RNA chaperone Hfq. This study reports the role of RyaA in mediating the cellular response to glucose-specific phosphoenolypyruvate phosphotransferase system (PTS)-dependent phosphosugar stress. Aiba and co-workers have shown that a block in the metabolism of glucose 6-phosphate causes transient growth inhibition and post-transcriptional regulation of ptsG, encoding the glucose-specific PTS transporter. We found that RyaA synthesis was induced by a non-metabolizable glucose phosphate analogue and was necessary for relief of the toxicity of glucose phosphate stress. Expression of RyaA was sufficient to cause a rapid loss of ptsG mRNA, probably reflecting degradation of the message mediated by RyaA:ptsG pairing. The ryaA gene was renamed sgrS, for sugar transport-related sRNA. Expression of sgrS is regulated by a novel transcriptional activator, SgrR (formerly YabN), which has a putative DNA-binding domain and a solute-binding domain similar to those found in certain transport proteins. Our results suggest that under conditions of glucose phosphate accumulation, SgrR activates SgrS synthesis, causing degradation of ptsG mRNA. Decreased ptsG mRNA results in decreased production of glucose transport machinery, thus limiting further accumulation of glucose phosphate. [source]

Rb(GaPO4)2(OH)(H2O)·H2O: a hydrated rubidium gallium phosphate analogue of GaPO4·2H2O and leucophosphite

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2002
Lionel Beitone
Crystals of the title hydrated rubidium gallium phosphate, rubidium aqua-,3 -hydroxo-di-,-phosphato-digallium hydrate, were synthesized hydro­thermally at 453,K under autogenous pressure. The solid crystallizes in the monoclinic system and its structure was determined from single-crystal X-ray diffraction analysis. It is similar to dihydrated gallium phosphate, GaPO4·2H2O, which is isostructural with the mineral leucophosphite. The structure is built up from a three-dimensional anionic framework composed of corner-linked octameric Ga4(PO4)4(OH)2(H2O)2 units. The Ga atom is in an octahedral coordination. Connection of the Ga4P4 species generates eight-ring channels, in which are encapsulated the Rb+ cations and water mol­ecules. [source]

Interaction of the Catalytic Domain of Inositol 1,4,5-Trisphosphate 3-Kinase A with Inositol Phosphate Analogues

CHEMBIOCHEM, Issue 8 2005
Alexandra Poinas Dr.
Abstract The levels of inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] in the cytoplasm are tightly regulated by two enzymes, Ins(1,4,5)P3 3-kinase and type I Ins(1,4,5)P3 5-phosphatase. The catalytic domain of Ins(1,4,5)P3 3-kinase (isoenzymes A, B and C) is restricted to approximately 275 amino acids at the C-terminal end. We were interested in understanding the catalytic mechanism of this key family of enzymes in order to exploit this in inhibitor design. We expressed the catalytic domain of rat Ins(1,4,5)P3 3-kinase A in Escherichia coli as a His- and S-tagged fusion protein. The purified enzyme was used in an Ins(1,4,5)P3 kinase assay to phosphorylate a series of inositol phosphate analogues with three or four phosphate groups. A synthetic route to D -2-deoxy-Ins(1,4,5)P3 was devised. D -2-Deoxy-Ins(1,4,5)P3 and D -3-deoxy-Ins(1,4,6)P3 were potent inhibitors of the enzyme, with IC50 values in the micromolar range. Amongst all analogues tested, only D -2-deoxy-Ins(1,4,5)P3 appears to be a good substrate of the Ins(1,4,5)P3 3-kinase. Therefore, the axial 2-hydroxy group of Ins(1,4,5)P3 is not involved in recognition of the substrate nor does it participate in the phosphorylation mechanism of Ins(1,4,5)P3. In contrast, the equatorial 3-hydroxy function must be present in that configuration for phosphorylation to occur. Our data indicate the importance of the 3-hydroxy function in the mechanism of inositol trisphosphate phosphorylation rather than in substrate binding. [source]