1t3t
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(New page: 200px<br /><applet load="1t3t" size="450" color="white" frame="true" align="right" spinBox="true" caption="1t3t, resolution 1.90Å" /> '''Structure of Formylg...)
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Revision as of 00:50, 21 November 2007
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Structure of Formylglycinamide synthetase
Overview
Formylglycinamide ribonucleotide amidotransferase (FGAR-AT) catalyzes the, ATP-dependent conversion of formylglycinamide ribonucleotide (FGAR) and, glutamine to formylglycinamidine ribonucleotide (FGAM), ADP, P(i), and, glutamate in the fourth step of the purine biosynthetic pathway. In, eukaryotes and Gram-negative bacteria, FGAR-AT is encoded by the purL gene, as a multidomain protein with a molecular mass of about 140 kDa. In, Gram-positive bacteria and archaebacteria FGAR-AT is a complex of three, proteins: PurS, PurL, and PurQ. We have determined the structure of, FGAR-AT (PurL) from Salmonella typhimurium at 1.9 A resolution using X-ray, crystallography. PurL is the last remaining enzyme in the purine, biosynthetic pathway to have its structure determined. The structure, reveals four domains: an N-terminal domain structurally homologous to a, PurS dimer, a linker region, an FGAM synthetase domain homologous to an, aminoimidazole ribonucleotide synthetase (PurM) dimer, and a triad, glutaminase domain. The domains are intricately linked by interdomain, interactions and peptide connectors. The fold common to PurM and the, central region of PurL represents a superfamily for which HypE, SelD, and, ThiL are predicted to be members. A structural ADP molecule was found, bound to a site related to the putative active site by pseudo-2-fold, symmetry and two sulfate ions were found at the putative active site., These observations and the structural similarities between PurM and StPurL, were used to model the substrates FGAR and ATP in the StPurL active site., A glutamylthioester intermediate was found in the glutaminase domain at, Cys1135. The N-terminal (PurS-like) domain is hypothesized to form the, putative channel through which ammonia passes from the glutaminase domain, to the FGAM synthetase domain.
About this Structure
1T3T is a Single protein structure of sequence from Salmonella typhimurium with MG, SO4 and ADP as ligands. Active as Phosphoribosylformylglycinamidine synthase, with EC number 6.3.5.3 Full crystallographic information is available from OCA.
Reference
Domain organization of Salmonella typhimurium formylglycinamide ribonucleotide amidotransferase revealed by X-ray crystallography., Anand R, Hoskins AA, Stubbe J, Ealick SE, Biochemistry. 2004 Aug 17;43(32):10328-42. PMID:15301531
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