1kkb

Complex of Escherichia coli Adenylosuccinate Synthetase with IMP and Hadacidin

spinqualitylabelsall models 1kkb, resolution 2.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1kkb is a 1 chain structure with sequence from Escherichia coli k-12. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: HDA, IMP Related: 1cib, 1kjx Activity: Adenylosuccinate synthase, with EC number 6.3.4.4 Resources: FirstGlance, OCA, RCSB, PDBsum Function [PURA_ECOLI] Plays an important role in the de novo pathway of purine nucleotide biosynthesis. Catalyzes the first committed step in the biosynthesis of AMP from IMP (By similarity).[HAMAP-Rule:MF_00011] 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 A complete set of substrate/substrate analogs of adenylosuccinate synthetase from Escherichia coli induces dimer formation and a transition from a disordered to an ordered active site. The most striking of the ligand-induced effects is the movement of loop 40-53 by up to 9 A. Crystal structures of the partially ligated synthetase, which either combine IMP and hadacidin or IMP, hadacidin, and Mg(2+)-pyrophosphate, have ordered active sites, comparable with the fully ligated enzyme. More significantly, a crystal structure of the synthetase with IMP alone exhibits a largely ordered active site, which includes the 9 A movement of loop 40-53 but does not include conformational adjustments to backbone carbonyl 40 (Mg(2+) interaction element) and loop 298-304 (L-aspartate binding element). Interactions involving the 5'-phosphoryl group of IMP evidently trigger the formation of salt links some 30 A away. The above provides a structural basis for ligand binding synergism, effects on k(cat) due to mutations far from the site of catalysis, and the complete loss of substrate efficacy due to minor alterations of the 5'-phosphoryl group of IMP. IMP Alone Organizes the Active Site of Adenylosuccinate Synthetase from Escherichia coli.,Hou Z, Wang W, Fromm HJ, Honzatko RB J Biol Chem. 2002 Feb 22;277(8):5970-6. Epub 2001 Dec 12. PMID:11741996 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Adenylosuccinate Synthetase

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