Validation of spermidine synthase as a drug target in African trypanosomes.


Taylor, MC; Kaur, H; Blessington, B; Kelly, JM; Wilkinson, SR; (2008) Validation of spermidine synthase as a drug target in African trypanosomes. The Biochemical journal, 409 (2). pp. 563-9. ISSN 0264-6021 DOI: https://doi.org/10.1042/BJ20071185

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Abstract

The trypanocidal activity of the ODC (ornithine decarboxylase) inhibitor DFMO (difluoromethylornithine) has validated polyamine biosynthesis as a target for chemotherapy. As DFMO is one of only two drugs used to treat patients with late-stage African trypanosomiasis, the requirement for additional drug targets is paramount. Here, we report the biochemical properties of TbSpSyn (Trypanosoma brucei spermidine synthase), the enzyme immediately downstream of ODC in this pathway. Recombinant TbSpSyn was purified and shown to catalyse the formation of spermidine from putrescine and dcSAM (decarboxylated S-adenosylmethionine). To determine the functional importance of TbSpSyn in BSF (bloodstream form) parasites, we used a tetracycline-inducible RNAi (RNA interference) system. Down-regulation of the corresponding mRNA correlated with a decrease in intracellular spermidine and cessation of growth. This phenotype could be complemented by expressing the SpSyn (spermidine synthase) gene from Leishmania major in cells undergoing RNAi, but could not be rescued by addition of spermidine to the medium due to the lack of a spermidine uptake capacity. These results therefore genetically validate TbSpSyn as a target for drug development and indicate that in the absence of a functional biosynthetic pathway, BSF T. brucei cannot scavenge sufficient spermidine from their environment to meet growth requirements.

Item Type: Article
Faculty and Department: Faculty of Infectious and Tropical Diseases > Dept of Pathogen Molecular Biology
Faculty of Infectious and Tropical Diseases > Dept of Clinical Research
Research Centre: Leishmaniasis Group
Neglected Tropical Diseases Network
Malaria Centre
PubMed ID: 17916066
Web of Science ID: 252915000025
URI: http://researchonline.lshtm.ac.uk/id/eprint/8715

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