title: Characterization of the Trypanosoma cruzi Rad51 gene and its role in recombination events associated with the parasite resistance to ionizing radiation.
abstract: 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.
authors.affiliation: Department of Biochemistry and Immunology, ICB, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Caixa Postal 486, Belo Horizonte 30161-970, MG, Brazil.
authors.forename: Carlos Gustavo
authors.initials: CG
authors.lastname: Regis-da-Silva
authors.forename: Jorge Marcelo
authors.initials: JM
authors.lastname: Freitas
authors.forename: Danielle Gomes
authors.initials: DG
authors.lastname: Passos-Silva
authors.forename: Carolina
authors.initials: C
authors.lastname: Furtado
authors.forename: Luiz
authors.initials: L
authors.lastname: Augusto-Pinto
authors.forename: Márcio Tadeu
authors.initials: MT
authors.lastname: Pereira
authors.forename: Wanderson Duarte
authors.initials: WD
authors.lastname: DaRocha
authors.forename: Glória Regina
authors.initials: GR
authors.lastname: Franco
authors.forename: Andréa Mara
authors.initials: AM
authors.lastname: Macedo
authors.forename: Jean-Sebastien
authors.initials: JS
authors.lastname: Hoffmann
authors.forename: Christophe
authors.initials: C
authors.lastname: Cazaux
authors.forename: Sérgio Danilo Junho
authors.initials: SD
authors.lastname: Pena
authors.forename: Santuza Maria Ribeiro
authors.initials: SM
authors.lastname: Teixeira
authors.forename: Carlos Renato
authors.initials: CR
authors.lastname: Machado
mesh_terms: 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*
chemical_list: D016054:DNA, Protozoan; D015800:Protozoan Proteins; D012333:RNA, Messenger; D016053:RNA, Protozoan; D051135:Rad51 Recombinase