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Rap1 and Cdc13 have complementary roles in preventing exonucleolytic degradation of telomere 5′ ends

Runnberg, Rikard LU ; Narayanan, Saishyam LU and Cohn, Marita LU (2017) In Scientific Reports 7(1).
Abstract

Telomere DNA ends with a single-stranded 3′ overhang. Long 3′ overhangs may cause aberrant DNA damage responses and accelerate telomere attrition, which is associated with cancer and aging, respectively. Genetic studies have indicated several important players in preventing 5′ end hyper-resection, yet detailed knowledge about the molecular mechanism in which they act is still lacking. Here, we use an in vitro DNA 5′ end protection assay, to study how N. castellii Cdc13 and Rap1 protect against 5′ exonucleolytic degradation by λ-exonuclease. The homogeneous telomeric repeat sequence of N. castellii allows us to study their protection ability at exact binding sites relative to the 5′ end. We find efficient protection by both Cdc13 and... (More)

Telomere DNA ends with a single-stranded 3′ overhang. Long 3′ overhangs may cause aberrant DNA damage responses and accelerate telomere attrition, which is associated with cancer and aging, respectively. Genetic studies have indicated several important players in preventing 5′ end hyper-resection, yet detailed knowledge about the molecular mechanism in which they act is still lacking. Here, we use an in vitro DNA 5′ end protection assay, to study how N. castellii Cdc13 and Rap1 protect against 5′ exonucleolytic degradation by λ-exonuclease. The homogeneous telomeric repeat sequence of N. castellii allows us to study their protection ability at exact binding sites relative to the 5′ end. We find efficient protection by both Cdc13 and Rap1 when bound close to the 5′ end. Notably, Rap1 provides protection when binding dsDNA at a distance from the 5′ end. The DNA binding domain of Rap1 is sufficient for 5′ end protection, and its wrapping loop region is essential. Intriguingly, Rap1 facilitates protection also when its binding site contains 2 nt of ssDNA, thus spanning across the ds-ss junction. These results highlight a role of Rap1 in 5′ end protection and indicate that Cdc13 and Rap1 have complementary roles in maintaining proper 3′ overhang length.

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organization
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type
Contribution to journal
publication status
published
subject
in
Scientific Reports
volume
7
issue
1
publisher
Nature Publishing Group
external identifiers
  • scopus:85027871660
  • wos:000407979900041
ISSN
2045-2322
DOI
10.1038/s41598-017-08663-x
language
English
LU publication?
yes
id
6642914d-0273-4c4f-b0ed-61f9abd0d8fe
date added to LUP
2017-09-05 11:06:44
date last changed
2018-01-07 12:17:53
@article{6642914d-0273-4c4f-b0ed-61f9abd0d8fe,
  abstract     = {<p>Telomere DNA ends with a single-stranded 3′ overhang. Long 3′ overhangs may cause aberrant DNA damage responses and accelerate telomere attrition, which is associated with cancer and aging, respectively. Genetic studies have indicated several important players in preventing 5′ end hyper-resection, yet detailed knowledge about the molecular mechanism in which they act is still lacking. Here, we use an in vitro DNA 5′ end protection assay, to study how N. castellii Cdc13 and Rap1 protect against 5′ exonucleolytic degradation by λ-exonuclease. The homogeneous telomeric repeat sequence of N. castellii allows us to study their protection ability at exact binding sites relative to the 5′ end. We find efficient protection by both Cdc13 and Rap1 when bound close to the 5′ end. Notably, Rap1 provides protection when binding dsDNA at a distance from the 5′ end. The DNA binding domain of Rap1 is sufficient for 5′ end protection, and its wrapping loop region is essential. Intriguingly, Rap1 facilitates protection also when its binding site contains 2 nt of ssDNA, thus spanning across the ds-ss junction. These results highlight a role of Rap1 in 5′ end protection and indicate that Cdc13 and Rap1 have complementary roles in maintaining proper 3′ overhang length.</p>},
  articleno    = {8729},
  author       = {Runnberg, Rikard and Narayanan, Saishyam and Cohn, Marita},
  issn         = {2045-2322},
  language     = {eng},
  month        = {12},
  number       = {1},
  publisher    = {Nature Publishing Group},
  series       = {Scientific Reports},
  title        = {Rap1 and Cdc13 have complementary roles in preventing exonucleolytic degradation of telomere 5′ ends},
  url          = {http://dx.doi.org/10.1038/s41598-017-08663-x},
  volume       = {7},
  year         = {2017},
}