1cib

STRUCTURE OF ADENYLOSUCCINATE SYNTHETASE FROM E. COLI COMPLEXED WITH GDP, IMP, HADACIDIN, AND NO3

spinqualitylabelsall models 1cib, resolution 2.30Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1cib 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: GDP, HDA, IMP, MG, NO3 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 Guanosine 5'-diphosphate 3'-diphosphate (ppGpp), a pleiotropic effector of the stringent response, potently inhibits adenylosuccinate synthetase from Escherichia coli as an allosteric effector and/or as a competitive inhibitor with respect to GTP. Crystals of the synthetase grown in the presence of IMP, hadacidin, NO3-, and Mg2+, then soaked with ppGpp, reveal electron density at the GTP pocket which is consistent with guanosine 5'-diphosphate 2':3'-cyclic monophosphate. Unlike ligand complexes of the synthetase involving IMP and GDP, the coordination of Mg2+ in this complex is octahedral with the side chain of Asp13 in the inner sphere of the cation. The cyclic phosphoryl group interacts directly with the side chain of Lys49 and indirectly through bridging water molecules with the side chains of Asn295 and Arg305. The synthetase either directly facilitates the formation of the cyclic nucleotide or scavenges trace amounts of the cyclic nucleotide from solution. Regardless of its mode of generation, the cyclic nucleotide binds far more tightly to the active site than does ppGpp. Conceivably, synthetase activity in vivo during the stringent response may be sensitive to the relative concentrations of several effectors, which together exercise precise control over the de novo synthesis of AMP. Effectors of the stringent response target the active site of Escherichia coli adenylosuccinate synthetase.,Hou Z, Cashel M, Fromm HJ, Honzatko RB J Biol Chem. 1999 Jun 18;274(25):17505-10. PMID:10364182 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Adenylosuccinate Synthetase

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