A bulged stem tethers Est1p to telomerase RNA in budding yeast

Anita G. Seto, April J. Livengood, Yehuda Tzfati, Elizabeth H. Blackburn, Thomas R. Cech*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

115 Scopus citations


It is well established that the template for telomeric DNA synthesis is provided by the RNA subunit of telomerase; however, the additional functions provided by most of the rest of the RNA (>1000 nucleotides in budding yeast) are largely unknown. By alignment of telomerase RNAs of Saccharomyces cerevisiae and six Kluyveromyces species followed by mutagenesis of the S. cerevisiae RNA, we found a conserved region that is essential for telomere maintenance. Phylogenetic analysis and computer folding revealed that this region is conserved not only in primary nucleotide sequence but also in secondary structure. A common bulged-stem structure was predicted in all seven yeast species. Mutational analysis showed the structure to be essential for telomerase function. Suppression of bulged-stem mutant phenotypes by overexpression of Est1p and loss of co-immunoprecipitation of the mutant RNAs with Estlp indicated that this bulged stem is necessary for association of Est1p, a telomerase regulatory subunit. Est1p in yeast extract bound specifically to a small RNA containing the bulged stem, suggesting a direct interaction. We propose that this RNA structure links the enzymatic core of telomerase with Estlp, thereby allowing Est1p to recruit or activate telomerase at the telomere.

Original languageAmerican English
Pages (from-to)2800-2812
Number of pages13
JournalGenes and Development
Issue number21
StatePublished - 1 Nov 2002


  • Est1p
  • RNA structure
  • TLC1
  • Telomerase
  • Yeast


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