1DBR

HYPOXANTHINE GUANINE XANTHINE

Summary for 1DBR

• Entry DOI: 10.2210/pdb1dbr/pdb
• Descriptor: HYPOXANTHINE GUANINE XANTHINE PHOSPHORIBOSYLTRANSFERASE, MAGNESIUM ION (3 entities in total)
• Functional Keywords: transferase, glycosyltransferase, purine salvage
• Biological source: Toxoplasma gondii
• Cellular location: Cytoplasm: Q26997
• Total number of polymer chains: 4
• Total formula weight: 106186.64

Authors

Schumacher, M.A.,Carter, D.,Roos, D.,Ullman, B.,Brennan, R.G. (deposition date: 1996-02-13, release date: 1997-12-03, Last modification date: 2024-02-07)

Primary citation

Schumacher, M.A.,Carter, D.,Ross, D.S.,Ullman, B.,Brennan, R.G.
Crystal structures of Toxoplasma gondii HGXPRTase reveal the catalytic role of a long flexible loop.
Nat.Struct.Biol., 3:881-887, 1996

PubMed Abstract: Crystal structures of substrate-free and XMP-soaked hypoxanthine-guanine-xanthine phosphoribosyltransferase (HGXPRTase) of the opportunistic pathogen Toxoplasma gondii have been determined to 2.4 and 2.9 A resolution, respectively. HGXPRTase displays the conserved PRTase fold. In the structure of the enzyme bound to its product, a long flexible loop (residues 115-126) is located away from the active site. Comparison to the substrate-free structure reveals a striking relocation of the loop, which is poised to cover the catalytic pocket, thus providing a mechanism by which the HG(X)PRTases shield their oxocarbonium transition states from nucleophilic attack by the bulk solvent. The conserved Ser 117-Tyr 118 dipeptide within the loop is brought to the active site, completing the ensemble of catalytic residues.

PubMed: 8836106
DOI: 10.1038/nsb1096-881

Experimental method

X-RAY DIFFRACTION (2.4 Å)