期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 108, 期 51, 页码 20362-20369出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1100281108
关键词
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资金
- US National Institutes of Health [GM43265]
- Damon RunyonRobert Black Cancer Research Foundation [DRG-1943-07]
In Saccharomyces cerevisiae, a Cdc13-Est1 interaction is proposed to mediate recruitment of telomerase to DNA ends. Here we provide unique in vitro evidence for this model by demonstrating a direct interaction between purified Cdc13 and Est1. The Cdc13-Est1 interaction is specific and requires the in vivo defined Cdc13 recruitment domain. Moreover, in the absence of this interaction, Est1 is excluded from telomeric single-stranded (ss) DNA. The apparent association constand (K(d)) between Est1 and a Cdc13-telomeric ssDNA complex was similar to 250 nM. In G2 phase cells, where telomerase is active, Cdc13 and Est1 were sufficiently abundant (similar to 420 and similar to 110 copies per cell, respectively) to support complex formation. Interaction between Cdc13 and Est1 was unchanged by three telomerase-deficient mutations, Cdc13(E252K) (cdc13-2), Est1(K444E) (est1-60), and Cdc13(S249,255D), indicating that their telomerase null phenotypes are not due to loss of the Cdc13-Est1 interaction. These data recapitulate in vitro the first step in telomerase recruitment to telomeric ssDNA and suggest that this step is necessary to recruit telomerase to DNA ends.
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