The finger subdomain of yeast telomerase cooperates with Pif1p to limit telomere elongation.
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.
SciCrunch is a data sharing and display platform. Anyone can create a custom portal where they can select searchable subsets of hundreds of data sources, brand their web pages and create their community. SciCrunch will push data updates automatically to all portals on a weekly basis. User communities can also add their own data to scicrunch, however this is not currently a free service.