4o4d

Crystal Structure of an Inositol hexakisphosphate kinase EhIP6KA in complexed with ATP and Ins(1,4,5)P3

spinqualitylabelsall models 4o4d, resolution 2.10Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4o4d is a 1 chain structure with sequence from Entamoeba histolytica HM-1:IMSS-A. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.1Å Ligands: ACT, ATP, I3P, MG, PO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function N9UNA8_ENTH1 Publication Abstract from PubMed Inositol trisphosphate kinases (IP3Ks) and inositol hexakisphosphate kinases (IP6Ks) each regulate specialized signalling activities by phosphorylating either InsP3 or InsP6 respectively. The molecular basis for these different kinase activities can be illuminated by a structural description of IP6K. Here we describe the crystal structure of an Entamoeba histolytica hybrid IP6K/IP3K, an enzymatic parallel to a 'living fossil'. Through molecular modelling and mutagenesis, we extrapolated our findings to human IP6K2, which retains vestigial IP3K activity. Two structural elements, an alpha-helical pair and a rare, two-turn 310 helix, together forge a substrate-binding pocket with an open clamshell geometry. InsP6 forms substantial contacts with both structural elements. Relative to InsP6, enzyme-bound InsP3 rotates 55 degrees closer to the alpha-helices, which provide most of the protein's interactions with InsP3. These data reveal the molecular determinants of IP6K activity, and suggest an unusual evolutionary trajectory for a primordial kinase that could have favored efficient bifunctionality, before propagation of separate IP3Ks and IP6Ks. IP6K structure and the molecular determinants of catalytic specificity in an inositol phosphate kinase family.,Wang H, DeRose EF, London RE, Shears SB Nat Commun. 2014 Jun 24;5:4178. doi: 10.1038/ncomms5178. PMID:24956979 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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