Trypanosomatid Biology and Euglenozoan Evolution: New Insights and Shifting Paradigms Revealed through Genome Sequencing

Some of the biochemical peculiarities that occur in trypanosomatid protozoa are relatively well known: compartmentalisation of glycolytic enzymes within microbodies of the peroxisome class, an almost complete absence of gene regulation at the level of transcript initiation, and editing of mitochondrial transcripts. With the recent arrival of complete genome sequences for three distinct trypanosomatid parasites (Berriman et al. 2005; El-Sayed et al., 2005a and El-Sayed et al., 2005b; Ivens et al. 2005), new insights into the unusual biology of this fascinating family of protozoan parasites, considered to occupy one of the deeper branches of eukaryotic phylogeny, are apparent. Focusing mainly in the general areas of genome architecture and metabolism, this overview discusses some biological and evolutionary insights that have arisen as a consequence of sequence availability for the medically relevant trypanosomatids Trypanosoma brucei, T. cruzi, and Leishmania major. Much of the disease burden caused by these parasites occurs in the developing world, typically afflicting poor or isolated communities. In the future, a key translational application will be integration of the trypanosomatid genome sequences into ongoing discovery and development programmes for much needed new drugs