RNAi identifies two hydroperoxide metabolising enzymes that are essential to the bloodstream form of the African trypanosome


Wilkinson, SR; Horn, D; Prathalingam, R; Kelly, JM; (2003) RNAi identifies two hydroperoxide metabolising enzymes that are essential to the bloodstream form of the African trypanosome. The Journal of biological chemistry, 278 (34). pp. 31640-6. ISSN 0021-9258 DOI: https://doi.org/10.1074/jbc.M303035200

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Abstract

Detoxification of hydroperoxides in trypanosomes is mediated by a series of linked redox pathways that are dependent on the parasite-specific thiol trypanothione for reducing equivalents. These pathways are characterised by differences in sub-cellular location, electron transport molecules and substrate-specificity. To determine the functional significance of the enzymes involved we have used a tetracycline-inducible RNA interference system to down-regulate expression of each of the corresponding transcripts in bloodstream form Trypanosoma brucei. We have identified two peroxidases, a cytosolic peroxiredoxin (TbCPX) and a member of the non-selenium glutathione-dependent peroxidase family (TbGPXI), that appear to be essential for the viability of this clinically relevant stage of the parasite life-cycle. Addition of tetracycline to the cultures resulted in a major reduction in mRNA levels and enzyme activity, a dramatic fall in growth rate and significant cell death. Furthermore, within 20 hours of adding tetracycline, cells in which the cytosolic peroxiredoxin transcript was targeted were found to be 16-fold more susceptible to killing by exogenous hydrogen peroxide. We also observed that knockdown of the tryparedoxin TbTPNI, a thioredoxin-like protein that facilitates electron transport to both TbCPX and TbGPXI, resulted in a reduction in growth rate. These experiments therefore identify redox pathways that are essential for oxidative defence in T. brucei and validate the corresponding peroxidases as targets for drug design.

Item Type: Article
Faculty and Department: Faculty of Infectious and Tropical Diseases > Dept of Pathogen Molecular Biology
PubMed ID: 12791697
Web of Science ID: 184782100024
URI: http://researchonline.lshtm.ac.uk/id/eprint/16483

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