Figure 4.

Top2-191 molecules lacking cleavage activity can relieve taz1Δ telomeric entanglement. (A) Cleavage-dead Top2-191 suppresses taz1Δ cold sensitivity. Strains bearing the indicated insertion at the lys1 locus were spotted on minimal medium lacking thiamine. (B) Cleavage-dead Top2-191 fails to provide the essential decatenation function of Top2. The indicated strains were streaked on YES medium. All clones were obtained from the same parental diploid and four clones of each genotype are shown. The survivors seen at 19°C in the top2-250 nmt81-top2-191-Y835F patches are likely to arise from gene conversion between the two top2 copies.