title: Role of AtMSH7 in UV-B-induced DNA damage recognition and recombination.
abstract: The mismatch repair (MMR) system maintains genome integrity by correcting replication-associated errors and inhibiting recombination between divergent DNA sequences. The basic features of the pathway have been highly conserved throughout evolution, although the nature and number of the proteins involved in this DNA repair system vary among organisms. Plants have an extra mismatch recognition protein, MutSγ, which is a heterodimer: MSH2-MSH7. To further understand the role of MSH7 in vivo, we present data from this protein in Arabidopsis thaliana. First, we generated transgenic plants that express β-glucuronidase (GUS) under the control of the MSH7 promoter. Histochemical staining of the transgenic plants indicated that MSH7 is preferentially expressed in proliferating tissues. Then, we identified msh7 T-DNA insertion mutants. Plants deficient in MSH7 show increased levels of UV-B-induced cyclobutane pyrimidine dimers relative to wild-type (WT) plants. Consistent with the patterns of MSH7 expression, we next analysed the role of the protein during somatic and meiotic recombination. The frequency of somatic recombination between homologous or homeologous repeats (divergence level of 1.6%) was monitored using a previously described GUS recombination reporter assay. Disruption of MSH7 has no effect on the rates of somatic homologous or homeologous recombination under control conditions or after UV-B exposure. However, the rate of meiotic recombination between two genetically linked seed-specific fluorescent markers was 97% higher in msh7 than in WT plants. Taken together, these results suggest that MSH7 is involved in UV-B-induced DNA damage recognition and in controlling meiotic recombination.
authors.affiliation: Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000 Rosario, Argentina Present address: Department of Biochemical and Pharmaceutical Technology, University of São Paulo, 05508-000 São Paulo, Brazil.
authors.forename: Luciana Daniela
authors.initials: LD
authors.lastname: Lario
authors.affiliation: Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000 Rosario, Argentina Present address: Biotechnology Department, Nidera S.A., Ruta 8 Km 376, 2600 Venado Tuerto, Santa Fe, Argentina.
authors.forename: Pablo
authors.initials: P
authors.lastname: Botta
authors.affiliation: Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000 Rosario, Argentina casati@cefobi-conicet.gov.ar spampinato@cefobi-conicet.gov.ar.
authors.forename: Paula
authors.initials: P
authors.lastname: Casati
authors.affiliation: Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000 Rosario, Argentina casati@cefobi-conicet.gov.ar spampinato@cefobi-conicet.gov.ar.
authors.forename: Claudia Patricia
authors.initials: CP
authors.lastname: Spampinato
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000502:physiology / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D004249:DNA Damage / Q000528:radiation effects; D004260:DNA Repair / Q000235:genetics*; D035264:Flowers / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D017930:Genes, Reporter; D016254:Mutagenesis, Insertional; D030821:Plants, Genetically Modified; D011740:Pyrimidine Dimers / Q000528:radiation effects; D011995:Recombination, Genetic; D036226:Seedlings / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D012639:Seeds / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: D029681:Arabidopsis Proteins; C499543:MSH7 protein, Arabidopsis; D011740:Pyrimidine Dimers
keywords: Arabidopsis thaliana; UV-B radiation.; meiotic recombination; mismatch repair; mitotic recombination; sequence divergence