1cg3

STRUCTURE OF THE MUTANT (R143L) OF ADENYLOSUCCINATE SYNTHETASE FROM E. COLI COMPLEXED WITH HADACIDIN, GDP, 6-PHOSPHORYL-IMP, AND MG2+

spinqualitylabelsall models 1cg3, resolution 2.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1cg3 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. Method: X-ray diffraction, Resolution 2.5Å Ligands: GDP, HDA, IMO, MG Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT 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 Asp13 and His41 are essential residues of adenylosuccinate synthetase, putatively catalyzing the formation of adenylosuccinate from an intermediate of 6-phosphoryl-IMP. Wild-type adenylosuccinate synthetase and three mutant synthetases (Arg143 --> Leu, Lys16 --> Gln, and Arg303 --> Leu) from Eschericha coli have been crystallized in the presence of IMP, hadacidin (an analogue of L-aspartate), Mg2+, and GTP. The active site of each complex contains 6-phosphoryl-IMP, Mg2+, GDP, and hadacidin, except for the Arg303 --> Leu mutant, which does not bind hadacidin. In response to the formation of 6-phosphoryl-IMP, Asp13 enters the inner coordination sphere of the active site Mg2+. His41 hydrogen bonds with 6-phosphoryl-IMP, except in the Arg303 --> Leu complex, where it remains bound to the guanine nucleotide. Hence, recognition of the active site Mg2+ by Asp13 evidently occurs after the formation of 6-phosphoryl-IMP, but recognition of the intermediate by His41 may require the association of L-aspartate with the active site. Structures reported here support a mechanism in which Asp13 and His41 act as the catalytic base and acid, respectively, in the formation of 6-phosphoryl-IMP, and then act together as catalytic acids in the subsequent formation of adenylosuccinate. Mechanistic implications from crystalline complexes of wild-type and mutant adenylosuccinate synthetases from Escherichia coli.,Choe JY, Poland BW, Fromm HJ, Honzatko RB Biochemistry. 1999 May 25;38(21):6953-61. PMID:10346917 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Adenylosuccinate synthetase 3D structures

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