FIG. 3.

Overexpression of telomerase proteins in the WT and the reg2Δ mutant. Genes encoding the K. lactis telomerase proteins Est1, Est2, Est3, Ku70, and Ku80, including their endogenous promoters, were cloned into a K. lactis 2μm, high-copy-number plasmid (pKDU7) and introduced into K. lactis cells containing WT (A) or reg2Δ ter1 mutants (B) on CEN-ARS plasmids. Cells were grown for six passages and analyzed by Southern blot hybridization as described in the legend of Fig. 1. Only BclI-specific hybridization is shown. (C) Typical colony phenotypes of K. lactis strains taken at their fourth passage. Impaired telomere maintenance is associated with rough colonies, as opposed to the smooth appearance of WT colonies. (D) Genomic DNA was prepared from an est3Δ strain in its sixth passage and analyzed by Southern blot hybridization as described in the legend of Fig. 1.