1T4A

Structure of B. Subtilis PurS C2 Crystal Form

Summary for 1T4A

• Entry DOI: 10.2210/pdb1t4a/pdb
• Related: 1GTD
• Descriptor: PurS (2 entities in total)
• Functional Keywords: purs, tetramer, complex formyl glycinamide synthetase, fgar, fgam, structural protein
• Biological source: Bacillus subtilis
• Total number of polymer chains: 2
• Total formula weight: 19909.50

Authors

Anand, R.,Hoskins, A.A.,Bennett, E.M.,Sintchak, M.D.,Stubbe, J.,Ealick, S.E. (deposition date: 2004-04-28, release date: 2004-09-14, Last modification date: 2024-10-16)

Primary citation

Anand, R.,Hoskins, A.A.,Bennett, E.M.,Sintchak, M.D.,Stubbe, J.,Ealick, S.E.
A model for the Bacillus subtilis formylglycinamide ribonucleotide amidotransferase multiprotein complex.
Biochemistry, 43:10343-10352, 2004

PubMed Abstract: Formylglycinamide ribonucleotide amidotransferase (FGAR-AT) catalyzes the conversion of formylglycinamide ribonucleotide (FGAR), ATP, and glutamine to formylglycinamidine ribonucleotide (FGAM), ADP, P(i), and glutamate in the fourth step of the purine biosynthetic pathway. PurL exists in two forms: large PurL (lgPurL) is a single chain, multidomain enzyme of about 1300 amino acids, whereas small PurL (smPurL) contains about 800 amino acids but requires two additional gene products, PurS and PurQ, for activity. smPurL contains the ATP and FGAR binding sites, PurQ is a glutaminase, and the function of PurS is just now becoming understood. We determined the structure of Bacillus subtilis PurS in two different crystal forms P2(1) and C2 at 2.5 and 2.0 A resolution, respectively. PurS forms a tight dimer with a central six-stranded beta-sheet flanked by four helices. In both the P2(1) and the C2 crystal forms, the quaternary structure of PurS is a tetramer. The concave faces of the PurS dimers interact via the C-terminal region to form a twelve-stranded beta-barrel with a hydrophilic core. We used the structure of PurS together with the structure of lgPurL from Salmonella typhimurium to construct a model of the PurS/smPurL/PurQ complex. The HisH (glutaminase) domain of imidazole glycerol phosphate synthetase was used as an additional model of PurQ. The model shows stoichiometry of 2PurS/smPurL/PurQ using a PurS dimer or 4PurS/2smPurL/2PurQ using a PurS tetramer. Both models place key conserved residues at the ATP/FGAR binding site and at a structural ADP binding site. The homology model is consistent with biochemical studies on the reconstituted complex.

PubMed: 15301532
DOI: 10.1021/bi0491292

Experimental method

X-RAY DIFFRACTION (2 Å)