The N-Terminal DNA-Binding Domain of Rad52 Promotes RAD51-Independent Recombination in Saccharomyces cerevisiae

摘要

In Saccharomyces cerevisiae , the Rad52 protein plays a role in both RAD51 -dependent and RAD51 -independent recombination pathways. We characterized a rad52 mutant, rad52-329 , which lacks the C-terminal Rad51-interacting domain, and studied its role in RAD51 -independent recombination. The rad52-329 mutant is completely defective in mating-type switching, but partially proficient in recombination between inverted repeats. We also analyzed the effect of the rad52-329 mutant on telomere recombination. Yeast cells lacking telomerase maintain telomere length by recombination. The rad52-329 mutant is deficient in RAD51 -dependent telomere recombination, but is proficient in RAD51 -independent telomere recombination. In addition, we examined the roles of other recombination genes in the telomere recombination. The RAD51 -independent recombination in the rad52-329 mutant is promoted by a paralogue of Rad52, Rad59. All components of the Rad50-Mre11-Xrs2 complex are also important, but not essential, for RAD51 -independent telomere recombination. Interestingly, RAD51 inhibits the RAD51 -independent, RAD52 -dependent telomere recombination. These findings indicate that Rad52 itself, and more precisely its N-terminal DNA-binding domain, promote an essential reaction in recombination in the absence of RAD51 .