title: Tel1 and Rad51 are involved in the maintenance of telomeres with capping deficiency.
abstract: Vertebrate-like T2AG3 telomeres in tlc1-h yeast consist of short double-stranded regions and long single-stranded overhang (G-tails) and, although based on Tbf1-capping activity, they are capping deficient. Consistent with this idea, we observe Y' amplification because of homologous recombination, even in the presence of an active telomerase. In these cells, Y' amplification occurs by different pathways: in Tel1(+) tlc1h cells, it is Rad51-dependent, whereas in the absence of Tel1, it depends on Rad50. Generation of telomeric G-tail, which is cell cycle regulated, depends on the MRX (Mre11-Rad50-Xrs2) complex in tlc1h cells or is MRX-independent in tlc1h tel1Δ mutants. Unexpectedly, we observe telomere elongation in tlc1h lacking Rad51 that seems to act as a telomerase competitor for binding to telomeric G-tails. Overall, our results show that Tel1 and Rad51 have multiple roles in the maintenance of vertebrate-like telomeres in yeast, supporting the idea that they may participate to evolutionary conserved telomere protection mechanism/s acting at uncapped telomeres.
authors.affiliation: Dipartimento di Biologia e Biotecnologie 'Charles Darwin', Sapienza Università di Roma, 00185 Rome, Italy. enea.didomenico@uniroma1.it
authors.forename: Enea Gino
authors.initials: EG
authors.lastname: Di Domenico
authors.forename: Stefano
authors.initials: S
authors.lastname: Mattarocci
authors.forename: Graziella
authors.initials: G
authors.lastname: Cimino-Reale
authors.forename: Paola
authors.initials: P
authors.lastname: Parisi
authors.forename: Noemi
authors.initials: N
authors.lastname: Cifani
authors.forename: Ettore
authors.initials: E
authors.lastname: D'Ambrosio
authors.forename: Virginia A
authors.initials: VA
authors.lastname: Zakian
authors.forename: Fiorentina
authors.initials: F
authors.lastname: Ascenzioni
mesh_terms: D004268:DNA-Binding Proteins / Q000235:genetics; D017353:Gene Deletion; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000502:physiology*; D051135:Rad51 Recombinase / Q000378:metabolism / Q000502:physiology*; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D019098:Telomerase / Q000037:antagonists & inhibitors; D016615:Telomere / Q000378:metabolism*; D059505:Telomere Homeostasis
chemical_list: D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; C086930:RAD50 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D017346:Protein Serine-Threonine Kinases; C513623:TEL1 protein, S cerevisiae; C495151:RAD51 protein, S cerevisiae; D051135:Rad51 Recombinase; D019098:Telomerase