Cloned (Comment) | Organism |
---|---|
recombinant expression of MBP-tagged EhIP6KA residues 32-270 | Entamoeba histolytica |
Crystallization (Comment) | Organism |
---|---|
purified recombinant MBP-tagged EhIP6KA residues 32-270, several crystal complexes of the IP6K including those that contain either large (Ins(1,3,4,5,6)P5 /InsP6) or small (Ins(1,4,5)P3) substrates, hanging drop vapor diffusion, 60 mg/ml protein in solution is mixed with reservoir solution containing 12% w/v PEG 3350, 50 mM NaH2PO4, pH 5.5 at 18°C, or by hanging drop vapor diffusion for one week against a well buffer containing 8% w/v PEG 3350, 100 mM Na3citrate, pH 5.2 at 25°C, followed by dilution microseeding for two weeks with a well buffer of 8% w/v PEG 3350, 100 mM Na3citrate, pH 5.2, and 8% ethylene glycol at 25°C, soaking of crystals in 22% w/v PEG 3350, 10 mM MgCl2, 10 mM ATP, 0.1 M sodium acetate, pH 5.2, and 20 mM InsP6, 10 mM Ins(1,3,4,5,6)P5 or 10 mM Ins(1,4,5)P3 for 3 days, X-ray diffraction structure determination and analysis, molecular replacement using MBP (1ez9) and IP3K (1w2c) as search models | Entamoeba histolytica |
Protein Variants | Comment | Organism |
---|---|---|
additional information | construction of an Entamoeba histolytica hybrid IP6K/IP3K chimeric hybrid through molecular modeling and mutagenesis | Entamoeba histolytica |
Metals/Ions | Comment | Organism | Structure |
---|---|---|---|
Mg2+ | required | Entamoeba histolytica |
Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
---|---|---|---|---|---|---|
ATP + 1D-myo-inositol hexakisphosphate | Entamoeba histolytica | - |
ADP + 1D-myo-inositol 5-diphosphate 1,2,3,4,6-pentakisphosphate | - |
? | |
additional information | Entamoeba histolytica | secondary to its InsP6 kinase activity, also phosphorylates the 6-OH of Ins(1,4,5)P3, an inositol phosphate multikinase (IPMK)-like activity. IPMK itself is positionally promiscuous in that it is a 3-, 5- and 6-kinase. The enzyme also shows significant InsP3 kinase activity | ? | - |
? |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Entamoeba histolytica | C4M387 | - |
- |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
ATP + 1D-myo-inositol hexakisphosphate | - |
Entamoeba histolytica | ADP + 1D-myo-inositol 5-diphosphate 1,2,3,4,6-pentakisphosphate | - |
? | |
additional information | secondary to its InsP6 kinase activity, also phosphorylates the 6-OH of Ins(1,4,5)P3, an inositol phosphate multikinase (IPMK)-like activity. IPMK itself is positionally promiscuous in that it is a 3-, 5- and 6-kinase. The enzyme also shows significant InsP3 kinase activity | Entamoeba histolytica | ? | - |
? | |
additional information | EhIP6KA, like mammalian IP6Ks, converts InsP6 to 5-InsP7. The 5-phosphate group on InsP6 is diphosphorylated by EhIP6KA. The enzyme phosphorylates Ins(1,3,4,5,6)P5, and the major product co-elutes with a PP-[3H]InsP4 standard, no InsP6 is formed. The first order rate constant for Ins(1,3,4,5,6)P5 phosphorylation is 40fold lower than that for InsP6. The rate of phosphorylation of Ins(1,4,5)P3, is 220fold slower than that for InsP6, either the 2- or the 6-OH of Ins(1,4,5)P3 are phosphorylated. Ins(1,4,5,6)P4 is the major InsP4 product formed from Ins(1,4,5)P, with phosphorylation of an inositol phosphate at the 2-position. Steric restrictions prevent InsP6 from occupying the same space as Ins(1,4,5)P3 in the substrate-binding pocket. Substrate binding and specificities, overview | Entamoeba histolytica | ? | - |
? |
Subunits | Comment | Organism |
---|---|---|
monomer | gel filtration and sequence calculation | Entamoeba histolytica |
More | enzyme structure determinaion and comparisons, similarities to enzymes human IP3KA, human IP6K, and Saccharomyces cerevisiae IPMK, overview | Entamoeba histolytica |
Synonyms | Comment | Organism |
---|---|---|
EhIP6KA | - |
Entamoeba histolytica |
IP6K | - |
Entamoeba histolytica |
Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
---|---|---|---|
37 | - |
assay at | Entamoeba histolytica |
pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
---|---|---|---|
7 | - |
assay at | Entamoeba histolytica |
Cofactor | Comment | Organism | Structure |
---|---|---|---|
ATP | binding site structure, overview | Entamoeba histolytica |
General Information | Comment | Organism |
---|---|---|
evolution | IP6Ks are members of a wider inositol phosphate kinase family (Pfam PF03770) that includes IPMKs and IP3Ks. These enzymes all share a PxxxDxKxG, PDKG, catalytic motif. Phylogenetic analysis indivates that this kinase family arose from a primordial IP6K precursor | Entamoeba histolytica |
additional information | structural analysis of the IP6K from Entamoeba histolytica | Entamoeba histolytica |