1NHT

ENTRAPMENT OF 6-THIOPHOSPHORYL-IMP IN THE ACTIVE SITE OF CRYSTALLINE ADENYLOSUCCINATE SYNTHETASE FROM ESCHERICHIA COLI DATA COLLECTED AT 100K

Summary for 1NHT

• Entry DOI: 10.2210/pdb1nht/pdb
• Descriptor: ADENYLOSUCCINATE SYNTHETASE, MAGNESIUM ION, GUANOSINE-5'-DIPHOSPHATE, ... (6 entities in total)
• Functional Keywords: ligase, synthetase, purine nucleotide biosynthesis, gtp-hydrolysing enzymes
• Biological source: Escherichia coli
• Cellular location: Cytoplasm: P0A7D4
• Total number of polymer chains: 1
• Total formula weight: 48301.44

Authors

Poland, B.W.,Bruns, C.A.,Fromm, H.J.,Honzatko, R.B. (deposition date: 1997-01-12, release date: 1997-10-08, Last modification date: 2024-02-14)

Primary citation

Poland, B.W.,Bruns, C.,Fromm, H.J.,Honzatko, R.B.
Entrapment of 6-thiophosphoryl-IMP in the active site of crystalline adenylosuccinate synthetase from Escherichia coli.
J.Biol.Chem., 272:15200-15205, 1997

PubMed Abstract: Crystal structures of adenylosuccinate synthetase from Escherichia coli complexed with Mg2+, 6-thiophosphoryl-IMP, GDP, and hadacidin at 298 and 100 K have been refined to R-factors of 0.171 and 0.206 against data to 2.8 and 2.5 A resolution, respectively. Interactions of GDP, Mg2+ and hadacidin are similar to those observed for the same ligands in the complex of IMP, GDP, NO3-, Mg2+ and hadacidin (Poland, B. W., Fromm, H. J. & Honzatko, R. B. (1996). J. Mol. Biol. 264, 1013-1027). Although crystals were grown from solutions containing 6-mercapto-IMP and GTP, the electron density at the active site is consistent with 6-thiophosphoryl-IMP and GDP. Asp-13 and Gln-224 probably work in concert to stabilize the 6-thioanion of 6-mercapto-IMP, which in turn is the nucleophile in the displacement of GDP from the gamma-phosphate of GTP. Once formed, 6-thiophosphoryl-IMP is stable in the active site of the enzyme under the conditions of the structural investigation. The direct observation of 6-thiophosphoryl-IMP in the active site is consistent with the putative generation of 6-phosphoryl-IMP along the reaction pathway of the synthetase.

PubMed: 9182542
DOI: 10.1074/jbc.272.24.15200

Experimental method

X-RAY DIFFRACTION (2.5 Å)