A novel allele of fission yeast rad11 that causes defects in DNA repair and telomere length regulation

Replication protein A (RPA) is a heterotrimeric single-stranded DNA-binding protein involved in DNA replication, recombination and repair. In Saccharomyces cerevisiae, several mutants in the RFA1 gene encoding the large subunit of RPA have been isolated and one of the mutants with a missense allele, rfa1-D228Y, shows a synergistic reduction in telomere length when combined with a yku70 mutation. So far, only one mutant allele of the rad11(+) gene encoding the large subunit of RPA has been reported in Schizosaccharomyces pombe. To study the role of S.pombe RPA in DNA repair and possibly in telomere maintenance, we constructed a rad11-D223Y mutant, which corresponds to the S.cerevisiae rfa1-D228Y mutant. rad11-D223Y cells were methylmethane sulfonate, hydroxyurea, UV and gamma-ray sensitive, suggesting that rad11-D223Y cells have a defect in DNA repair activity. Unlike the S.cerevisiae rfa1-D228Y mutation, the rad11-D223Y mutation itself caused telomere shortening. Moreover, Rad11-Myc bound to telomere in a ChIP assay. These results strongly suggest that RPA is directly involved in telomere maintenance.