Characterization of the Trypanosoma cruzi Rad51 gene and its role in recombination events associated with the parasite resistance to ionizing radiation.
The Rad51 gene encodes a highly conserved enzyme involved in DNA double-strand break (DSB) repair and recombination processes. We cloned and characterized the Rad51 gene from Trypanosoma cruzi, the protozoan parasite that causes Chagas disease. This gene is expressed in all three forms of the parasite life cycle, with mRNA levels that are two-fold more abundant in the intracellular amastigote form. The recombinase activity of the TcRad51 gene product was verified by an increase in recombination events observed in transfected mammalian cells expressing TcRad51 and containing two inactive copies of the neomycin-resistant gene. As a component of the DSB repair machinery, we investigated the role of TcRad51 in the resistance to ionizing radiation and zeocin treatment presented by T. cruzi. When exposed to gamma irradiation, different strains of the parasite survive to dosages as high as 1 kGy. A role for TcRad51 in this process was evidenced by the increased expression of its mRNA after irradiation. Furthermore, transfected parasites over-expressing TcRad51 have a faster kinetics of recovery of the normal pattern of chromosomal bands after irradiation as well as a higher resistance to zeocin treatment than do wild-type cultures.
Regis-da-Silva
Carlos Gustavo
CG
Department of Biochemistry and Immunology, ICB, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Caixa Postal 486, Belo Horizonte 30161-970, MG, Brazil.
Freitas
Jorge Marcelo
JM
Passos-Silva
Danielle Gomes
DG
Furtado
Carolina
C
Augusto-Pinto
Luiz
L
Pereira
Márcio Tadeu
MT
DaRocha
Wanderson Duarte
WD
Franco
Glória Regina
GR
Macedo
Andréa Mara
AM
Hoffmann
Jean-Sebastien
JS
Cazaux
Christophe
C
Pena
Sérgio Danilo Junho
SD
Teixeira
Santuza Maria Ribeiro
SM
Machado
Carlos Renato
CR
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016466:CHO Cells; D006224:Cricetinae; D016054:DNA, Protozoan / Q000235:genetics; D005720:Gamma Rays; D017125:Genes, Protozoan; D006801:Humans; D008969:Molecular Sequence Data; D015800:Protozoan Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016053:RNA, Protozoan / Q000235:genetics / Q000378:metabolism; D051135:Rad51 Recombinase / Q000235:genetics*; D011836:Radiation Tolerance / Q000235:genetics; D011995:Recombination, Genetic; D017386:Sequence Homology, Amino Acid; D014349:Trypanosoma cruzi / Q000201:enzymology / Q000235:genetics* / Q000472:pathogenicity / Q000528:radiation effects*
D016054:DNA, Protozoan; D015800:Protozoan Proteins; D012333:RNA, Messenger; D016053:RNA, Protozoan; D051135:Rad51 Recombinase