Distinct roles for yeast Stn1 in telomere capping and telomerase inhibition.

The budding yeast Cdc13, Stn1 and Ten1 (CST) proteins are proposed to function as an RPA-like complex at telomeres that protects ('caps') chromosome ends and regulates their elongation by telomerase. We show that Stn1 has a critical function in both processes through the deployment of two separable domains. The N ...
terminus of Stn1 interacts with Ten1 and carries out its essential capping function. The C terminus of Stn1 binds both Cdc13 and Pol12, and we present genetic data indicating that the Stn1-Cdc13 interaction is required to limit continuous telomerase action. Stn1 telomere association, similar to that of Cdc13, peaks during S phase. Significantly, the magnitude of Stn1 telomere binding is independent of telomere TG tract length, suggesting that the negative effect of Stn1 on telomerase action might be regulated by a modification of CST activity or structure in cis at individual telomeres. Genetic analysis suggests that the Tell kinase exerts an effect in parallel with the Stn1 C terminus to counteract its inhibition of telomerase. These data provide new insights into the coordination of telomere capping and telomerase regulation.
Mesh Terms:
Cell Cycle Proteins, Chromosomal Proteins, Non-Histone, Genes, Fungal, Mutation, Protein Binding, Protein Structure, Tertiary, Recombinant Fusion Proteins, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Telomerase, Telomere, Telomere-Binding Proteins
EMBO J.
Date: Sep. 03, 2008
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