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The Est1 Subunit of Saccharomyces cerevisiae Telomerase Makes Multiple Contributions to Telomere Length Maintenance
- Source :
- Genetics. 162:1101-1115
- Publication Year :
- 2002
- Publisher :
- Oxford University Press (OUP), 2002.
-
Abstract
- The telomerase-associated Est1 protein of Saccharomyces cerevisiae mediates enzyme access by bridging the interaction between the catalytic core of telomerase and the telomere-binding protein Cdc13. In addition to recruiting telomerase, Est1 may act as a positive regulator of telomerase once the enzyme has been brought to the telomere, as previously suggested by the inability of a Cdc13-Est2 fusion protein to promote extensive telomere elongation in an est1-Δ strain. We report here three classes of mutant Est1 proteins that retain association with the telomerase enzyme but confer different in vivo consequences. Class 1 mutants display a telomere replication defect but are capable of promoting extensive telomere elongation in the presence of a Cdc13-Est2 fusion protein, consistent with a defect in telomerase recruitment. Class 2 mutants fail to elongate telomeres even in the presence of the Cdc13-Est2 fusion, which is the phenotype predicted for a defect in the proposed second regulatory function of EST1. A third class of mutants impairs an activity of Est1 that is potentially required for the Ku-mediated pathway of telomere length maintenance. The isolation of mutations that perturb separate functions of Est1 demonstrates that a telomerase holoenzyme subunit can contribute multiple regulatory roles to telomere length maintenance.
- Subjects :
- Telomerase
Saccharomyces cerevisiae Proteins
Amino Acids, Acidic
Protein subunit
DNA Mutational Analysis
Telomere-Binding Proteins
Saccharomyces cerevisiae
Mutation, Missense
Biology
Telomerase RNA component
Gene Expression Regulation, Fungal
Genetics
Telomerase reverse transcriptase
Amino Acid Sequence
Conserved Sequence
Telomere-binding protein
Amino Acids, Basic
Telomere
biology.organism_classification
Fusion protein
Mutagenesis, Site-Directed
Sequence Alignment
Research Article
Subjects
Details
- ISSN :
- 19432631
- Volume :
- 162
- Database :
- OpenAIRE
- Journal :
- Genetics
- Accession number :
- edsair.doi.dedup.....caa622cf40775cc0edb808aa9a1845be