The Telomere Protein Taz1 Is Required to Prevent and Repair Genomic DNA Breaks

Abstract

One fundamental function of telomeres is to prevent the ends of chromosomes from being sensed and treated as DNA damage. Here we present evidence for additional roles of telomeres in promoting proper chromosome segregation and DNA repair. We find that the fission yeast telomere protein Taz1p is required for cell cycle progression at 20°C, a temperature at which taz1Δ cells exhibit a G2/M DNA damage checkpoint delay, chromosome missegregation, and DNA double-strand breaks (DSBs). Spindle assembly checkpoint components and a checkpoint-independent function of Rad3p are required for taz1Δ cells to survive at 20°C. Disruption of topoisomerase II activity suppresses the cold sensitivity of taz1Δ cells, suggesting a scenario in which telomeric entanglement is the primary defect. Furthermore, hypersensitivity to treatments that induce DSBs suggests that Taz1p is involved in DSB repair. Our observations imply roles for Taz1p-containing telomeres in preventing and repairing DNA breaks throughout the genome.