Download MendeleyStructure and mechanism of the 6-oxopurine nucleosidase from Trypanosoma brucei brucei
Vandemeulebroucke, A., Minici, C., Bruno, I., Muzzolini, L., Tornaghi, P., Parkin, D.W., Versees, W., Steyaert, J., Degano, M.(2010) Biochemistry 49: 8999-9010
- PubMed: 20825170 Search on PubMed
- DOI: https://doi.org/10.1021/bi100697d
- Primary Citation Related Structures:
3FZ0 - PubMed Abstract:
Trypanosomes are purine-auxotrophic parasites that depend upon nucleoside hydrolase (NH) activity to salvage nitrogenous bases necessary for nucleic acid and cofactor synthesis. Nonspecific and purine-specific NHs have been widely studied, yet little is known about the 6-oxopurine-specific isozymes, although they are thought to play a primary role in the catabolism of exogenously derived nucleosides. Here, we report the first functional and structural characterization of the inosine-guanosine-specific NH from Trypanosoma brucei brucei. The enzyme shows near diffusion-limited efficiency coupled with a clear specificity for 6-oxopurine nucleosides achieved through a catalytic selection of these substrates. Pre-steady-state kinetic analysis reveals ordered product release, and a rate-limiting structural rearrangement that is associated with the release of the product, ribose. The crystal structure of this trypanosomal NH determined to 2.5 Å resolution reveals distinctive features compared to those of both purine- and pyrimidine-specific isozymes in the framework of the conserved and versatile NH fold. Nanomolar iminoribitol-based inhibitors identified in this study represent important lead compounds for the development of novel therapeutic strategies against trypanosomal diseases.
- Department of Molecular and Cellular Interactions and Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium.
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