title: MR (Mre11-Rad50) complex in Giardia duodenalis: In vitro characterization and its response upon DNA damage.
abstract: Giardia duodenalis is a well-known protozoan parasite of humans and other mammals. The repair of DNA double strand breaks (DSBs) is crucial for genomic stability and homologous recombination is one of the primary mechanisms used by cells to repair DNA. The Mre11 complex is comprised by Mre11, an endonuclease and 3'-5' exonuclease known to resect ends during homologous recombination, and Rad50, a member of the structural maintenance of chromosomes (SMC) family of ATPases. In this work we cloned, expressed and characterized the catalytic activities of the giardial Mre11 (GdMre11) and Rad50 (GdRad50) proteins. Our results show that while purified recombinant GdMre11 and GdRad50 proteins bind DNA, GdMre11 contains a 3'-5' exonuclease and purified recombinant GdRad50 has ATPase activity. The predicted structure for GdMre11 revealed a conserved Mn(2+) dependent binding pocket. We also explored the expression of giardial mre11 and rad50 genes after ionizing radiation, and our results indicate that both specific transcripts were increased after 1-2 h while their protein levels were found to be significantly increased 4 h after gamma radiation treatment. These proteins were localized in the nuclei before and after irradiation. The implication of these observations is discussed.
authors: Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Av. Instituto Politécnico Nacional No. 2508, C.P. 07360, México D.F., Mexico. Electronic address: asandoval@cinvestav.mx.
authors: A
authors: A
authors: Sandoval-Cabrera
authors: Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Av. Instituto Politécnico Nacional No. 2508, C.P. 07360, México D.F., Mexico. Electronic address: nalu100@gmail.com.
authors: A L
authors: AL
authors: Zarzosa-Álvarez
authors: Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Av. Instituto Politécnico Nacional No. 2508, C.P. 07360, México D.F., Mexico. Electronic address: rmmartinez@cinvestav.mx.
authors: R M
authors: RM
authors: Martínez-Miguel
authors: Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Av. Instituto Politécnico Nacional No. 2508, C.P. 07360, México D.F., Mexico. Electronic address: roberm@cinvestav.mx.
authors: R M
authors: RM
authors: Bermúdez-Cruz
mesh_terms: D053903:DNA Breaks, Double-Stranded; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016829:Giardia lamblia / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D015800:Protozoan Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D015800:Protozoan Proteins; D011994:Recombinant Proteins
keywords: DNA repair; Double strand breaks; Giardia duodenalis; Mre11; Rad50