3a8t

Plant adenylate isopentenyltransferase in complex with ATP

spinqualitylabelsall models 3a8t, resolution 2.37Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3a8t is a 1 chain structure with sequence from Humulus lupulus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.37Å Ligands: ATP, PO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function IPT_HUMLU Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed Cytokinins are important plant hormones, and their biosynthesis most begins with the transfer of isopentenyl group from dimethylallyl diphosphate (DMAPP) to the N6-amino group of adenine by either adenylate isopentenyltransferase (AIPT) or tRNA-IPT. Plant AIPTs use ATP/ADP as an isopentenyl acceptor and bacterial AIPTs prefer AMP, whereas tRNA-IPTs act on specific sites of tRNA. Here, we present the crystal structure of an AIPT-ATP complex from Humulus lupulus (HlAIPT), which is similar to the previous structures of Agrobacterium AIPT and yeast tRNA-IPT. The enzyme is structurally homologous to the NTP-binding kinase family of proteins but forms a solvent-accessible channel that binds to the donor substrate DMAPP, which is directed toward the acceptor substrate ATP/ADP. When measured with isothermal titration calorimetry, some nucleotides displayed different binding affinities to HlAIPT with an order of ATP > dATP approximately ADP > GTP > CTP > UTP. Two basic residues Lys275 and Lys220 in HlAIPT interact with the beta and gamma-phosphate of ATP. By contrast, the interactions are absent in Agrobacterium AIPT because they are replaced by the acidic residues Asp221 and Asp171. Despite its structural similarity to the yeast tRNA-IPT, HlAIPT has evolved with a different binding strategy for adenylate. Crystal structure and substrate specificity of plant adenylate isopentenyltransferase from Humulus lupulus: distinctive binding affinity for purine and pyrimidine nucleotides.,Chu HM, Ko TP, Wang AH Nucleic Acids Res. 2010 Mar;38(5):1738-48. Epub 2009 Dec 10. PMID:20007608 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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