Telomere synthesis depends on telomerase, which contains an RNA subunit linked to a specialized reverse transcriptase subunit and several associated proteins. Here we report the characterization of four mutations in the yeast reverse transcriptase subunit Est2p that cause an overelongation of telomeres and an increase in the association of Est1p with telomeres during S phase. These 'up-mutations' are clustered in the finger subdomain of the reverse transcriptase. We show that the catalytic properties of the up-mutant telomerases are not improved in vitro. In vivo, the up-mutations neither bypass the activation step governed by Cdc13p nor do they uncouple telomerase from the Rap1p inhibition pathway. In the presence of the up-mutations, however, the ability of the Pif1p helicase to decrease telomere length and to inhibit the association of Est1p with telomeres is impaired. In addition, Pif1p associates in vivo with the telomerase RNA (TLC1) in a way that depends on the finger subdomain. We propose that, in addition to its catalytic role, the finger subdomain of Est2p facilitates the action of Pif1p at telomeres.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Annotation Extension||Reference|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Assay||Construct||Conditions||Strain Background||Reference|