Mutation of the Mbp1/Swi4 consensus binding (MCB/SCB) site affects telomere length. (A) Southern blot analysis of telomere lengths of the CSHY76 strain carrying TLC1 (WT) or TLC1 with different mutations in its promoter: mcb1a, mcb2, or mcb1/2a. Average changes in Y′ telomere length from three independent clones are indicated at the bottom ± SEM. S denotes senescing cells that have unstable telomere length. (B) Southern blot analysis of telomere length of a strain carrying TLC1 (WT) or tlc1-mcb1/2 (mcb1/2b) grown for 25–220 generations. The tlc1Δ strain was grown for 25 generations. Changes in Y′ telomere length for cells grown for the indicated number of generations relative to the WT grown for the corresponding number of generations are indicated at the bottom. n/a indicates not applicable because the telomeres of these cells were taken as length reference for the corresponding mcb1/2 mutants. S denotes senescing cells that have unstable telomere length.
