Structural basis for non-competitive product inhibition in human thymidine phosphorylase: implications for drug design
| Autor: | Annelies Bronckaers, Jan Balzarini, Sandra Liekens, David K. Stammers, María-Jesús Pérez-Pérez, Kamel El Omari |
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| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
Protein Conformation
Stereochemistry Pyrimidine-nucleoside phosphorylase Crystallography X-Ray Ligands Biochemistry Structure-Activity Relationship 03 medical and health sciences chemistry.chemical_compound 0302 clinical medicine Protein structure Humans Binding site Thymidine phosphorylase Molecular Biology 030304 developmental biology Thymidine Phosphorylase 0303 health sciences Binding Sites Cell Biology 3. Good health Thymine chemistry Product inhibition Drug Design 030220 oncology & carcinogenesis Thymidine Nucleoside Protein Binding Research Article |
| Popis: | HTP (human thymidine phosphorylase), also known as PD-ECGF (platelet-derived endothelial cell growth factor) or gliostatin, has an important role in nucleoside metabolism. HTP is implicated in angiogenesis and apoptosis and therefore is a prime target for drug design, including antitumour therapies. An HTP structure in a closed conformation complexed with an inhibitor has previously been solved. Earlier kinetic studies revealed an ordered release of thymine followed by ribose phosphate and product inhibition by both ligands. We have determined the structure of HTP from crystals grown in the presence of thymidine, which, surprisingly, resulted in bound thymine with HTP in a closed dead-end com-plex. Thus thymine appears to be able to reassociate with HTP after its initial ordered release before ribose phosphate and induces the closed conformation, hence explaining the mechanism of non-competitive product inhibition. In the active site in one of the four HTP molecules within the crystal asymmetric unit, additional electron density is present. This density has not been previously seen in any pyrimidine nucleoside phosphorylase and it defines a subsite that may be exploitable in drug design. Finally, because our crystals did not require proteolysed HTP to grow, the structure reveals a loop (residues 406–415), disordered in the previous HTP structure. This loop extends across the active-site cleft and appears to stabilize the dimer interface and the closed conformation by hydrogen-bonding. The present study will assist in the design of HTP inhibitors that could lead to drugs for anti-angiogenesis as well as for the potentiation of other nucleoside drugs. |
| Databáze: | OpenAIRE |
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