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PMID:20523746

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Citation

Bonetti, D, Clerici, M, Anbalagan, S, Martina, M, Lucchini, G and Longhese, MP (2010) Shelterin-like proteins and Yku inhibit nucleolytic processing of Saccharomyces cerevisiae telomeres. PLoS Genet. 6:e1000966

Abstract

Eukaryotic cells distinguish their chromosome ends from accidental DNA double-strand breaks (DSBs) by packaging them into protective structures called telomeres that prevent DNA repair/recombination activities. Here we investigate the role of key telomeric proteins in protecting budding yeast telomeres from degradation. We show that the Saccharomyces cerevisiae shelterin-like proteins Rif1, Rif2, and Rap1 inhibit nucleolytic processing at both de novo and native telomeres during G1 and G2 cell cycle phases, with Rif2 and Rap1 showing the strongest effects. Also Yku prevents telomere resection in G1, independently of its role in non-homologous end joining. Yku and the shelterin-like proteins have additive effects in inhibiting DNA degradation at G1 de novo telomeres, where Yku plays the major role in preventing initiation, whereas Rif1, Rif2, and Rap1 act primarily by limiting extensive resection. In fact, exonucleolytic degradation of a de novo telomere is more efficient in yku70Delta than in rif2Delta G1 cells, but generation of ssDNA in Yku-lacking cells is limited to DNA regions close to the telomere tip. This limited processing is due to the inhibitory action of Rap1, Rif1, and Rif2, as their inactivation allows extensive telomere resection not only in wild-type but also in yku70Delta G1 cells. Finally, Rap1 and Rif2 prevent telomere degradation by inhibiting MRX access to telomeres, which are also protected from the Exo1 nuclease by Yku. Thus, chromosome end degradation is controlled by telomeric proteins that specifically inhibit the action of different nucleases.

Links

PubMed PMC2877729 Online version:10.1371/journal.pgen.1000966

Keywords

DNA Damage; Hydrolysis; Saccharomyces cerevisiae/genetics; Saccharomyces cerevisiae Proteins/physiology; Telomere

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

YEAST:RIF1

involved_in

GO:0016233: telomere capping

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

YEAST:RIF2

involved_in

GO:0016233: telomere capping

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete


See also

References

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