A conserved template-proximal paired element in telomerase RNAs from budding yeasts. (A) A paired element located 5′ of the template region of Saccharomyces cerevisiae telomerase RNA was found by computer folding prediction. This long-range interaction is comprised of pairing between S. cerevisiae nucleotides 142–148 and 460–466 and resembles a similar element found in Kluyveromyces lactis telomerase RNA. (B) Mutations made in the S. cerevisiae telomerase RNA to test the predicted template-proximal paired element. Mutations were constructed in a CEN low-copy expression vector with TLC1 RNA expression driven from its endogenous promoter. Disruption Mutant A (DMA) replaced the sequence of paired element A with the sequence of paired element B. Disruption Mutant B (DMB) replaced the sequence of paired element B with the sequence of paired element A. Disruption Mutant C (DMC) combined the DMA and DMB mutations to restore the pairing potential with a different sequence on both sides of the stem.
