Identification of synthetic lethal mutation with pot1 deletion

Deletion of pot1+ causes rapidly telomere degradation and chromosome circularization. We searched gene which becomes synthetically lethal with pot1 deletion. We obtained novel pik1 mutant that is synthetically lethal with pot1 disruption. We found PI4P in Golgi is reduced in pik1-1 mutant. To investigate the mechanism of the lethality of pot1 pik1-1 double mutant, we constructed nmt-pot1-aid pik1-1 strain, where using of Thiamine and Auxin in nmt-pot1-aid strain causes Pot1 shutoff that leads to immediate telomere loss and chromosome circularization, and found pik1-1 mutation does not affect telomere resection and chromosome circularization. Thus, our results suggest that pik1 is required for the maintenance of circular chromosomes.