| Autor: |
Grandin, Nathalie, Damon, Christelle, Charbonneau, Michel |
| Zdroj: |
Molecular and Cellular Biology; November 2000, Vol. 20 Issue: 22 p8397-8408, 12p |
| Abstrakt: |
ABSTRACTThe Saccharomyces cerevisiae CDC13protein binds single-strand telomeric DNA. Here we report the isolation of new mutant alleles of CDC13that confer either abnormal telomere lengthening or telomere shortening. This deregulation not only depended on telomerase (Est2/TLC1) and Est1, a direct regulator of telomerase, but also on the yeast Ku proteins, yKu70/Hdf1 and yKu80/Hdf2, that have been previously implicated in DNA repair and telomere maintenance. Expression of a Cdc13-yKu70 fusion protein resulted in telomere elongation, similar to that produced by a Cdc13-Est1 fusion, thus suggesting that yKu70 might promote Cdc13-mediated telomerase recruitment. We also demonstrate that Stn1 is an inhibitor of telomerase recruitment by Cdc13, based both onSTN1overexpression and Cdc13-Stn1 fusion experiments. We propose that accurate regulation of telomerase recruitment by Cdc13 results from a coordinated balance between positive control by yKu70 and negative control by Stn1. Our results represent the first evidence of a direct control of the telomerase-loading function of Cdc13 by a double-strand telomeric DNA-binding complex. |
| Databáze: |
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