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Rap1p and telomere length regulation in yeast
S Marcand1, D Wotton, E Gilson
1Department of Microbiology, College of Physicians & Surgeons of Columbia University, NY 10032, USA.
Ciba Foundation Symposium
|January 1, 1997
Summary
Telomere length in yeast is controlled by Rap1p, Rif1p, and Rif2p proteins. A negative feedback loop senses Rap1p levels to regulate telomere repeat length.
Area of Science:
- Molecular Biology
- Genetics
- Yeast Biology
Background:
- Telomere length in Saccharomyces cerevisiae is tightly regulated, maintaining a narrow distribution of TG1-3 repeats.
- The protein Rap1p binds telomeric repeats and influences telomere length; mutations or deletions in its C-terminus alter length regulation.
Purpose of the Study:
- To further investigate the role of Rap1p in telomere length regulation.
- To elucidate the mechanism by which Rap1p controls telomere length in yeast.
Main Methods:
- Investigated the effects of Rap1p mutations and deletions on telomere length.
- Studied the interaction of Rap1p with other proteins involved in telomere regulation, specifically Rif1p and Rif2p.
Main Results:
- Telomere length appears to be regulated by a negative feedback mechanism dependent on the number of Rap1p molecules bound to chromosome ends.
- Telomere length regulation requires the proteins Rif1p and Rif2p, which interact with each other and the Rap1p C-terminus.
- The Rap1p C-terminal domain's role in telomere position effect (transcriptional silencing) is distinct from and antagonistic to its role in length regulation.
Conclusions:
- Telomere length in yeast is controlled by a feedback mechanism sensing Rap1p concentration.
- Rif1p and Rif2p are crucial components of this telomere length regulatory pathway.
- Rap1p's functions in telomere length control and transcriptional silencing are separable and opposing.