Conservation of poly(ADP-ribose) glycohydrolase activity in trypanosome parasites.

VILCHEZ LARREA S C; SCHLESINGER M; ALONSO G D; FLAWIA M M; FERNANDEZ VILLAMIL S H

San Luis

Congreso; XLVII Reunión Anual de SAIB; 2011

SAIB

Poly(ADP-ribose) polymers (PAR) are attached to specific target proteins in an early cellular response to DNA damage. Poly(ADP-ribose)glycohydrolase (PARG) represents the main PAR hydrolyzing activity in the cell via endo- and exo-glycosidic cleavage. The biological functions of PARG involve the PAR cycling required for structural chromatin remodeling during DNA repair, transcription, DNA replication and cell death pathways. Trypanosoma cruzi and T. brucei PARGs single-copy genes were identified in our laboratory. In silico analysis showed a high conservation of PARG catalytic domain and the presence of the three essential acidic residues (D-E-E). TcPARG mRNA was down regulated in mammalian host-stages amastigotes and trypomastigotes, while in the insect stage (epimastigote) it was up-regulated, in accordance with the protein expression determined by western blot. TbPARG was also expressed in bloodstream and procyclic forms of T. brucei.  In both parasites, these enzymes showed nuclear localization despite the absence of DNA damage. T. cruzi overexpressing PARG increased the growth ratio about 40% when compared to wild type, suggesting a role even under physiological conditions. Native PARG activity was evaluated by measuring PAR turnover by dot blot and using specific inhibitors, which are currently being investigated on their effect on T. cruzi and T. brucei growth.