SUMOylation is a relevant protein post-translational modification in eukaryotes. 
The C terminus of proteolytically activated small ubiquitin-like modifier (SUMO) 
is covalently linked to a lysine residue of the target protein by an isopeptide 
bond, through a mechanism that includes an E1-activating enzyme, an 
E2-conjugating enzyme, and transfer to the target, sometimes with the assistance 
of a ligase. The modification is reversed by a protease, also responsible for 
SUMO maturation. A number of proteins have been identified as SUMO targets, 
participating in the regulation of cell cycle progression, transcription, 
translation, ubiquitination, and DNA repair. In this study, we report that 
orthologous genes corresponding to the SUMOylation pathway are present in the 
etiological agent of Chagas disease, Trypanosoma cruzi. Furthermore, the 
SUMOylation system is functionally active in this protozoan parasite, having the 
requirements for SUMO maturation and conjugation. Immunofluorescence analysis 
showed that T. cruzi SUMO (TcSUMO) is predominantly found in the nucleus. To 
identify SUMOylation targets and get an insight into their physiological roles 
we generated transfectant T. cruzi epimastigote lines expressing a double-tagged 
T. cruzi SUMO, and SUMOylated proteins were enriched by tandem affinity 
chromatography. By two-dimensional liquid chromatography-mass spectrometry a 
total of 236 proteins with diverse biological functions were identified as 
potential T. cruzi SUMO targets. Of these, metacaspase-3 was biochemically 
validated as a bona fide SUMOylation substrate. Proteomic studies in other 
organisms have reported that orthologs of putative T. cruzi SUMOylated proteins 
are similarly modified, indicating conserved functions for protein SUMOylation 
in this early divergent eukaryote.