Structure and mechanism of the 6-oxopurine nucleosidase from trypanosoma brucei brucei

An Vandemeulebroucke, Claudia Minici, Ilaria Bruno, Laura Muzzolini, Paola Tornaghi, David W. Parkin, Wim Versées, Jan Steyaert, Massimo Degano

Research output: Contribution to journalArticlepeer-review


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.

Original languageEnglish
Pages (from-to)8999-9010
Number of pages12
Issue number41
Publication statusPublished - Oct 19 2010

ASJC Scopus subject areas

  • Biochemistry
  • Medicine(all)


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