4aqk
Inositol 1,3,4,5,6-pentakisphosphate 2-kinase in complex with ADP and IP6
Structural highlights
FunctionIPPK_ARATH Phosphorylates Ins(1,3,4,5,6)P5 at position 2 to form Ins(1,2,3,4,5,6)P6 (InsP6 or phytate). Phytate is a regulator of intracellular signaling, a highly abundant animal antinutrient, and a phosphate store in plant seeds. Also phosphorylates Ins(1,3,4,6)P4 and Ins(1,4,5,6)P4 to produce Ins(1,2,3,4,6)P5 and Ins(1,2,4,5,6)P5.[1] [2] Publication Abstract from PubMedInositol 1,3,4,5,6-pentakisphosphate 2-kinase (IP(5) 2-K) is a key enzyme that catalyzes the synthesis of phytic acid (IP(6)) from inositol 1,3,4,5,6-pentakisphosphate (IP(5)) and ATP. The first structure of IP(5) 2-K, that from Arabidopsis thaliana, has been solved previously; it only crystallized in the presence of inositol, either the substrate IP(5) or the product IP(6), and failed to crystallize in its free state (without inositol). Based on structural analysis, a point mutation of IP(5) 2-K (W129A) has been produced in order to overcome this limitation and obtain information about protein conformational changes upon substrate binding. Here, the production and crystallization of W129A IP(5) 2-K in its free state and with bound nucleotide is described. These crystals differed from the native crystals and belonged to the orthorhombic space group P2(1)2(1)2, with unit-cell parameters a = 66.00, b = 68.23, c = 105.80 A and a = 63.06, b = 71.80, c = 100.23 A, respectively. The crystals diffracted to resolutions of 2.22 A (apo) and 2.05 A (nucleotide bound) using synchrotron radiation and contained one molecule per asymmetric unit. The structures have been determined using the molecular-replacement method and refinement is being undertaken. Expression, purification, crystallization and preliminary X-ray diffraction analysis of the apo form of InsP5 2-K from Arabidopsis thaliana.,Banos-Sanz JI, Sanz-Aparicio J, Brearley CA, Gonzalez B Acta Crystallogr Sect F Struct Biol Cryst Commun. 2012 Jun 1;68(Pt 6):701-4. doi:, 10.1107/S1744309112017307. Epub 2012 May 23. PMID:22684075[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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