Nanbu T, Takahashi K, Murray JM, Hirata N, Ukimori S, Kanke M, Masukata H, Yukawa M, Tsuchiya E, Ueno M

Pot1 binds to single-stranded telomere overhangs and protects chromosome ends. RecQ helicases regulate homologous recombination at multiple stages including resection, strand displacement and resolution. Double mutants between fission yeast pot1 and the RecQ helicase rqh1 are synthetically lethal but the mechanism is not fully understood. Here, we show that the ...

Read More

synthetic lethality of pot1 rqh1 double mutants is due to inappropriate homologous recombination as it is suppressed by deletion of rad51(+). The expression of Rad51 in the pot1 rqh1 rad51 triple mutant, which has circular chromosomes, is lethal. Reduction of expression of Rqh1 in a pot1 disruptant with circular chromosomes caused chromosome mis-segregation and this defect was partially suppressed by deletion of rad51(+). Taken together, our results suggest that Rqh1 is required for the maintenance of circular chromosomes when homologous recombination is active. Crossovers between circular monomeric chromosomes generate dimers that cannot segregate properly in E. coli. We propose that Rqh1 inhibits crossovers between circular monomeric chromosomes to suppress the generation of circular dimers.

Date: Jan. 07, 2013

View in: Pubmed Google Scholar

149648