Steve Ealick's Research Group

Salmonella typhimurium Formylglycinamide Ribonucleotide Amidotransferase (StPurL)

PDB files:



Formylglycinamide ribonucleotide amidotransferase (FGAR-AT) catalyzes the ATP-dependent conversion of formylglycinamide ribonucleotide (FGAR), and glutamine to formylglycinamidine ribonucleotide (FGAM), ADP, Pi 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 and is comprised of 1295 amino acids. This structure of FGAR-AT (PurL) from Salmonella typhimurium at 1.9 Å resolution is the last remaining enzyme in the purine biosynthetic pathway to have its structure determined.

There is one molecule of StPurL in the asymmetric unit.


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The structure reveals four domains: an N-terminal domain structurally homologous to a PurS dimer (1-140; shown in green), a linker domain (141-214; shown in yellow), an FGAM synthetase domain homologous to an aminoimidazole ribonucleotide synthetase (PurM) dimer (215-979; shown in blue), and a triad glutaminase domain (980-1295; shown in red).

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A ribbon diagram of the proposed FGAM synthetase active site appears at right. The dashed line indicates the only disordered loop in StPurL spanning residues 448 to 466.

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Anand R, Hoskins AA, Stubbe J, and Ealick SE. Domain Organization of Salmonella typhimurium Formylglycinamide Ribonucleotide Amidotransferase Revealed by X-ray Crystallography. Biochemistry 43:10328 - 10342 (2004).

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