TcPARP a novel DNA damage dependent poly(ADP-ribose)polymerase from Trypanosoma cruzi.

HÉCTOR N. TORRES; GUILLERMO D. ALONSO; RODRIGO BALTANAS; MIRTHA M. FLAWIÁ; SILVIA H. FERNANDEZ VILLAMIL

Washington, DC, USA.

Congreso; Experimental Biology Annual Meeting.; 2007

Poly(ADP-ribose)polymerase (PARP) is a nuclear enzyme present in most eukaryotes. Its activity depends on DNA strand breaks and has been involved in processes such as DNA replication, DNA repair and gene expression. Here we describe for the first time the cloning and characterization of a poly(ADP-ribose)polymerase from Trypanosoma cruzi (TcPARP). This enzyme absolutely required DNA for catalytic activity and nicked DNA strongly enhanced it. T. cruzi purified histones increased TcPARP activity and the covalent attachment of [32P]ADP-ribose to these proteins was demonstrated. The enzyme was active in the absence of divalent cations. It was inhibited by 3-aminobenzamide, nicotinamide, theophylline, thymidine and histamine, but not by menadione. We demonstrated that TcPARP automodification resulted inhibitory. TcPARP was localized into the cell nucleus. PAR synthesis was confirmed in vivo by indirect immunofluorescence with anti-PAR antibodies. When T. cruzi epimastigotes were exposed to DNA damaging agents, PAR formation drastically increased in the nucleus. We have also found the catabolic counterpart, poly(ADP-ribose)glycohydrolase, in T. cruzi genome databases. These results suggest an analogy with the known poly(ADP-ribose) metabolism in higher eukaryotes and point out a physiological role for PARP in trypanosomatid DNA repair.