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| Crystal structures of Toxoplasma gondii HGXPRTase reveal the catalytic role of a long flexible loop |
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| Author(s): Schumacher MA, Carter D, Roos DS, Ullman B, Brennan RG |
| Source: NATURE STRUCTURAL BIOLOGY Volume: 3 Issue: 10 Pages: 881-887 Published: OCT 1996 |
| Times Cited: 73 References: 38 |
| 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 Angstrom 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 HC(X)PRTases shield their oxocarbonium transition states from nucleophilic attack by the bu Ik solvent. The conserved Ser 117-Tyr 118 dipeptide within the loop is brought to the active site, completing the ensemble of catalytic residues. |
| Document Type: Article |
| Language: English |
Addresses:
1. OREGON HLTH SCI UNIV, DEPT BIOCHEM & MOL BIOL, PORTLAND, OR 97201 USA
2. UNIV PENN, DEPT BIOL, PHILADELPHIA, PA 19104 USA |
| Publisher: NATURE PUBLISHING CO, 345 PARK AVE SOUTH, NEW YORK, NY 10010-1707 |
| Subject Category: Biochemistry & Molecular Biology; Biophysics; Cell Biology |
| IDS Number: VK993 |
| ISSN: 1072-8368 |
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| | | | | | | | | Record from Web of Science® | | | | | | | | | |