Lipid biosynthesis/metabolism in protozoan parasites

There are currently no effective treatments against many of the debilitating and fatal diseases caused by insect-transmitted protozoan parasites such as Trypanosoma brucei (African sleeping sickness), Trypanosoma cruzi (Chagas's) Leshmania, Plasmodium (malaria) and Toxoplasma. The cell-surface's of these parasites are covered in glycosylphosphatidylinositol (GPI) anchors and related molecules (1). T. brucei biosynthesis of GPI anchors are required for their abundant variant surface glycoprotein which protects them against the harsh environment of the bloodstream. This GPI anchor biosynthesis is a proven genetic and chemical target for therapeutic drugs (2-4). Our research is concerned with the biosynthetic pathways of the building blocks required for GPI assembly (PI, PE, Dol-P-Man and other related phospho- and glyco-lipids). We are finding significant exploitable differences between human and parasitic biosynthetic pathways and enzymes (5-6). Inhibitor studies and chemical synthesis followed by screening of focussed compounds libraries for lead compounds will ultimately result in therapeutic drugs against these Third World diseases.

The multi-disciplinary research approach involves:

1. In vivo and in vitro biosynthetic studies, to investigate how the parasites de novo synthesise their lipids and GPIs.
2. Bioinformatics, molecular biology and molecular parasitology are used to clone novel genes, allowing gene-knockout and/or RNAi approaches to genetically validate them as drug targets (3).
3. Biochemical phenotyping of these modified parasites using labelling methods, quantification of metabolites and proteins, enzymatic assays, various mass spec methods and lipidomic approaches to help us understand the parasite’s responses.
4. Recombinant expression and development of enzymatic assays, ultimately for high-throughput screening, in conjunction with the design and chemical synthesis of biosynthetic inhibitors as drug leads.

SELECTED RECENT PUBLICATIONS

1. Ferguson, M.A.J. et al Biochim. Biophys. Acta 1999 1455: 327-340.
2. Nagamune, K. et al Proc. Natl. Acad. Sci. U.S.A. 2000 97: 10336-10341.
3. Chang, T. et al J. Biol. Chem. 2004 277: 50176-50182
4. Smith, T.K. et al EMBO J. 2004 23: 4701-4708.
5. Smith, T.K. et al EMBO J. 2001 20: 3322-3332.
6. Smith, T.K. et al J. Biol. Chem. 2002 277: 37147-37153

OTHER PUBLICATIONS FROM THE GROUP

1. Smith, T.K. et al JBC 282 (44) 32042-32042.
2. Richmond, G. & Smith, T.K., BJ 2007405 (2), pp. 319-329
3. Byres, E. Smith, T.K. and Hunter WN. J Mol Biol 2007 371 (2), pp. 540-553.
4. Richmond G.S. and Smith, T.K. Molec Micro 2007 63 (4), pp. 1078-1095.
5. Martin, K. & Smith, T.K. BJ 2006 396: 287-295.
6. Martin, K. & Smith, T.K. Molec Micro 2006 61(1): 89-105.