ROLE OF AtMSH7 IN UV-B-INDUCED DNA DAMAGE RECOGNITION AND RECOMBINATION

LARIO, L.; BOTTA, P.; CASATI, P.; SPAMPINATO, C.

Rosario

Congreso; L Reunión de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB); 2014

Highly conserved DNA mismatch repair (MMR) systems promote genomic stability by correcting DNA replication errors, antagonizing homeologous recombination and responding to various DNA lesions. The first step of the pathway involves recognition of the DNA lesion by MutS proteins. Higher plants contain an extra MutS protein named MutSγ (MSH2-MSH7). To further understand the in vivo role of MSH7, we present data from this protein in Arabidopsis thaliana. Histochemical staining of transgenic plants that express the β-glucuronidase (GUS) under the control of the MSH7 promoter indicated that MSH7 is restricted to proliferating tissues. Then, we identified msh7 T-DNA insertion mutants. Plants deficient in MSH7 show increased levels of UV-B-induced cyclobutane pyrimidine dimers (CPDs) relative to wild-type (WT) plants. We next analyzed the role MSH7 during somatic recombination between homologous or homeologous repeats (divergence level of 1.6%) using a GUS recombination reporter assay. Disruption of MSH7 has no effect on the rates of somatic 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.