Fig. 4: Tay1 modulates Blm helicase activity and functionally resembles Blm in regulating telomere replication and recombination.
a The helicase activity of Blm (12.5 nM) on a non-telomeric substrate was examined in the presence of increasing Tay1 concentrations (0, 10, 30, and 90 nM). The quantified results are shown on the right. b The helicase activity of Blm (25 nM) on a telomeric DNA-containing substrate was examined in the presence of increasing Tay1 concentrations (0, 20, 40, and 80 nM). The quantified results are shown on the right. A higher concentration of Blm was chosen for these assays than those in (a) in order to accentuate the inhibitory effect of Tay1. c Chromosomal DNAs were isolated from three independent cultures of wild type or mutant strains and subjected to telomere restriction fragment analysis. The phosphor scan of the blot is shown along with the plot of telomere lengths (average ± SEM, n = 3 biologically independent samples) for each strain. The mutant strains were all passaged for ~75 generations before the analysis. d Chromosomal DNAs were isolated from the indicated strains (grown in YPD), and subjected to telomere restriction fragment Southern analysis. The ku70nar1 tay1∆ samples 1–3 are from three independently constructed strains. e Chromosomal DNAs were isolated from the indicated strains with the given growth condition, and subjected to duplicate C-circle assays. The scan of the blot is shown on the left and the quantification (means; n = 2 experimental replicates; normalized against the average value of ku70nar1 samples) plotted on the right.
