Dataset Information

Telomerase activation after recruitment in fission yeast.

ABSTRACT: Current models depict that telomerase recruitment equates to activation. Telomeric DNA-binding proteins and the telomerase accessory proteins coordinate the recruitment of telomerase to the ends of chromosomes in a telomere length- and cell-cycle-dependent manner [1-4]. Recent studies have demonstrated that the telomeric protein TPP1 and its binding protein TIN2 are key proteins for both telomerase recruitment and processivity in mammalian cells [5-7]. Although the precise molecular mechanism of telomerase recruitment has not yet been established, targeted point mutations within the oligonucleotide/oligosaccharide-binding (OB)-fold domain of TPP1 have been shown to impair telomerase association and processivity [8-10]. In fission yeast, telomerase is recruited through an interaction between the telomerase subunit Est1 and Ccq1, a component of the Pot1-Tpz1 telomere complex (POT1-TPP1 orthologs) [11-15]. Here, we demonstrate that association of telomerase with telomeres does not engage activity. We describe a mutation of Tpz1 that causes critical telomere shortening despite telomeric accumulation of the telomerase catalytic subunit, Trt1. Furthermore, Est1-directed telomerase association with Ccq1 is transient, and the Est1-Ccq1 interaction does not remain the bridge between telomeres and telomerase. Rather, direct interaction of Trt1 with Tpz1 is critical for telomere elongation. Moreover, Ccq1, which has been well characterized as a telomerase recruiter, is also required for the activation of telomere-associated telomerase. Our findings reveal a layer of telomerase regulation that controls activity after recruitment.

SUBMITTER: Armstrong CA

PROVIDER: S-EPMC4159562 | biostudies-literature | 2014 Sep

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Telomerase activation after recruitment in fission yeast.

Armstrong Christine Anne CA Pearson Siân Rosanna SR Amelina Hanna H Moiseeva Vera V Tomita Kazunori K

Current biology : CB 20140814 17

Current models depict that telomerase recruitment equates to activation. Telomeric DNA-binding proteins and the telomerase accessory proteins coordinate the recruitment of telomerase to the ends of chromosomes in a telomere length- and cell-cycle-dependent manner [1-4]. Recent studies have demonstrated that the telomeric protein TPP1 and its binding protein TIN2 are key proteins for both telomerase recruitment and processivity in mammalian cells [5-7]. Although the precise molecular mechanism of ...[more]

PMID: 25131669

Similar Datasets

Project description:In both fission yeast and humans, the shelterin complex plays central roles in regulation of telomerase recruitment, protection of telomeres against DNA damage response factors, and formation of heterochromatin at telomeres. While shelterin is essential for limiting activation of the DNA damage checkpoint kinases ATR and ATM at telomeres, these kinases are required for stable maintenance of telomeres. In fission yeast, Rad3ATR and Tel1ATM kinases are redundantly required for telomerase recruitment, since Rad3ATR/Tel1ATM-dependent phosphorylation of the shelterin subunit Ccq1 at Thr93 promotes interaction between Ccq1 and the telomerase subunit Est1. However, it remained unclear how protein-protein interactions within the shelterin complex (consisting of Taz1, Rap1, Poz1, Tpz1, Pot1 and Ccq1) contribute to the regulation of Ccq1 Thr93 phosphorylation and telomerase recruitment. In this study, we identify domains and amino acid residues that are critical for mediating Tpz1-Ccq1 and Tpz1-Poz1 interaction within the fission yeast shelterin complex. Using separation of function Tpz1 mutants that maintain Tpz1-Pot1 interaction but specifically disrupt either Tpz1-Ccq1 or Tpz1-Poz1 interaction, we then establish that Tpz1-Ccq1 interaction promotes Ccq1 Thr93 phosphorylation, telomerase recruitment, checkpoint inhibition and telomeric heterochromatin formation. Furthermore, we demonstrate that Tpz1-Poz1 interaction promotes telomere association of Poz1, and loss of Poz1 from telomeres leads to increases in Ccq1 Thr93 phosphorylation and telomerase recruitment, and telomeric heterochromatin formation defect. In addition, our studies establish that Tpz1-Poz1 and Tpz1-Ccq1 interactions redundantly fulfill the essential telomere protection function of the shelterin complex, since simultaneous loss of both interactions caused immediate loss of cell viability for the majority of cells and generation of survivors with circular chromosomes. Based on these findings, we suggest that the negative regulatory function of Tpz1-Poz1 interaction works upstream of Rad3ATR kinase, while Tpz1-Ccq1 interaction works downstream of Rad3ATR kinase to facilitate Ccq1 Thr93 phosphorylation and telomerase recruitment.

Dataset Information

Telomerase activation after recruitment in fission yeast.

Publications

Telomerase activation after recruitment in fission yeast.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets