SUMO modification of Top1 affects growth of vps25 cells. (A) The SUMO-TOP1 plasmid (pWJ1763) was transformed into VPS25 wild-type (W7981-2A) and vps25▵ mutant strains (W5911-1A). The wild-type TOP1 (pWJ1439) and the empty vector (pWJ1512) were also transformed as controls. Cultures were grown overnight, 10-fold serially diluted, and 5-μL drops were spotted onto plates with 0, 100, or 200 μM CuSO4. (B) Doubling times of strains were calculated after measuring growth in liquid cultures by optical density at 600 nm. All TOP1 mutant alleles are integrated in place of the corresponding wild-type allele. In the VPS25 wild-type background, the designated strains are: TOP1 (W8402-1A), top1-KR (EJY457), top1-YF (W8646-2B), top1-KR, YF (W8643-2D). In the vps25 mutant background the designated strains are: TOP1 (W8402-1C), top1-KR (W8402-1B), top1-YF (W8646-2A), top1-KR, YF (W8643-4A).
