Artigo
Biochemical studies with DNA polymerase beta and DNA polymerase beta-PAK of Trypanosoma cruzi suggest the involvement of these proteins in mitochondrial DNA maintenance
Fecha
2008-11-01Registro en:
Dna Repair. Amsterdam: Elsevier B.V., v. 7, n. 11, p. 1882-1892, 2008.
1568-7864
10.1016/j.dnarep.2008.07.018
WOS:000260949000011
Autor
Lopes, Debora de Oliveira
Fonseca Schamber-Reis, Bruno Luiz
Regis-da-Silva, Carlos Gustavo
Rajao, Matheus Andrade
DaRocha, Wanderson Duarte
Macedo, Andrea Mara
Franco, Gloria Regina
Nardelli, Sheila Cristina [UNIFESP]
Schenkman, Sergio [UNIFESP]
Hoffmann, Jean-Sebastein
Cazaux, Christophe
Junho Pena, Sergio Danilo
Ribeiro Teixeira, Santuza Maria
Machado, Carlos Renato
Institución
Resumen
Mammalian DNA polymerase p is a nuclear enzyme involved in the base excision and single-stranded DNA break repair pathways. in trypanosomatids, this protein does not have a defined cellular localization, and its function is poorly understood. We characterized two Trypanosoma cruzi proteins homologous to mammalian DNA polymerase beta, TcPol beta and TcPol beta PAK, and showed that both enzymes localize to the parasite kinetoplast. in vitro assays with purified proteins showed that they have DNA polymerization and deoxyribose phosphate lyase activities. Optimal conditions for polymerization were different for each protein with respect to dNTP concentration and temperature, and TcPol beta PAK, in comparison to TcPol beta, conducted DNA synthesis over a much broader pH range. TcPol beta was unable to carry out mismatch extension or DNA synthesis across 8-oxodG lesions, and was able to discriminate between dNTP and ddNTP. These specific abilities of TcPol beta were not observed for TcPol beta PAK or other X family members, and are not due to a phenylalanine residue at position 395 in the C-terminal region of TcPol beta, as assessed by a site-directed mutagenesis experiment reversing this residue to a well conserved tyrosine. Our data suggest that both polymerases from T. cruzi could cooperate to maintain mitochondrial DNA integrity through their multiple roles in base excision repair, gap filling and translesion synthesis. (C) 2008 Elsevier B.V. All rights reserved.