Figure 1.

An altered CPT sensitivity was shown by T729 mutants when expressed in yeast. Exponential cultures of EKY3 (top1Δ) cells transformed with vector control YCp50, YCpGAL1-hTOP1, YCpGAL1-htop1Ala653Pro,Thr718Ala [a known CPT resistant mutant (29)], YCpGAL1-htop1Thr729Ala, YCpGAL1-htop1Thr729Pro, YCpGAL1-htop1Thr729Lys and YCpGAL1-htop1Thr729Glu were serially 10-fold diluted and spotted onto SC-uracil plates supplemented with dextrose (Dex) or galactose (Gal) and, as indicated, CPT. Cell viability was assessed following incubation at 30°C.