Poly ADP-ribosilation in trypanosomatids in response to DNA damage.

RODRIGO BALTANÁS; GUILLERMO D. ALONSO; SALOMÉ VILCHEZ LARREA; MIRTHA M. FLAWIÁ; HÉCTOR N. TORRES; SILVIA H. FERNÁNDEZ VILLAMIL

Rosario, Santa Fé, Argentina

Congreso; XLII Reunión Anual de la Sociedad Argentina de investigaciones Bioquimicas; 2006

Sociedad Argentina de Investigaciones Bioquímicas

Poly(ADP-ribose)polymerase (PARP) is a nuclear enzyme present in most eukaryotes. Its activity depends on the presence of DNA strand breaks (DNAsb) and has been involved in many important genomic processes such as DNA replication, DNA repair and gene expression. The poly(ADP-ribose) polymer (PAR) is catabolized by the poly(ADP-ribose)glycohydrolase (PARG). Previously we reported the cloning and expression of Trypanosoma cruzi and Trypanosoma brucei genes for PARP-2 homologues (TcPARP and TbPARP). The present work, describes the biochemical and functional characterization of all these enzymes. We have also found, cloned and expressed the catabolic counterpart PARG, suggesting an analogous metabolism to the known in higher eukaryotes. In silico analysis of TcPARP and TbPARP showed conserved WGR, regulatory and catalytic domains. TcPARP and TbPARP activities were strongly activated by DNAsb. We also demonstrated the attachment of PAR synthesized by TcPARP, to it-self and to T. cruzi histones by using SDS-PAGE and autoradiography. PAR synthesis was confirmed in vivo by indirect immunofluorescence assay with antiPAR antibodies. Under standard growth conditions T. cruzi epimastigotes display low signal at the nucleus, which drastically increased when the cells were exposed to DNA damaging agents. These results point out a physiological role for PARP in trypanosomatids DNA repair systems.