Delivery of yeast telomerase to a DNA break depends on the recruitment functions of Cdc13 and Est1.
The yeast single-strand TG-repeat telomere binding protein Cdc13 and the telomerase accessory protein Est1 play essential roles in chromosome end replication. To determine whether a proposed Cdc13-Est1 interaction recruits telomerase (Est2), we used a simplified system in which telomere formation was monitored at an HO-induced DNA double-strand break (DSB). Tethering of either Cdc13 or Est1 adjacent to a DSB promoted telomere formation, and tethering of Est1, even in the absence of a DSB, resulted in the recruitment of Est2. Est1 association with a DSB containing an adjacent short TG-repeat sequence depended on the Cdc13-Est1 interaction affected by cdc13-2 and est1-60 mutations, whereas Cdc13 association did not. Similarly, Est2 binding to the DSB also required the Cdc13-Est1 interaction, but not synthesis of new TG repeats at the break site. These data demonstrate a critical role for Est1 in recruiting telomerase to its site of action, in cooperation with the telomere binding protein Cdc13.
Bianchi
Alessandro
A
Department of Molecular Biology and NCCR "Frontiers in Genetics" Program, University of Geneva, Sciences III, 30, Quai Ernest-Ansermet, CH-1211, Geneva 4, Switzerland.
Negrini
Simona
S
Shore
David
D
D004247:DNA / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism; D009154:Mutation; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D019098:Telomerase / Q000378:metabolism*; D034501:Telomere-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015003:Yeasts / Q000235:genetics / Q000378:metabolism
C452219:Cdc13 protein, S cerevisiae; D004268:DNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; D034501:Telomere-Binding Proteins; C081647:high affinity DNA-binding factor, S cerevisiae; D004247:DNA; C099024:EST1 protein, S cerevisiae; C509185:EST2 protein, S cerevisiae; D019098:Telomerase