Dataset Information

Yeast telomere capping protein Stn1 overrides DNA replication control through the S phase checkpoint.

ABSTRACT: Telomere integrity is maintained through end-protection proteins that block nuclease degradation and prevent telomeres from being recognized as DNA breaks. Although less well understood, end protection proteins may also play a role in facilitating telomere replication. Here, we show that overproduction (OP) of the yeast telomere capping protein Stn1 makes cells highly sensitive to the replication inhibitors hydroxyurea (HU) and methyl-methane sulfonate (MMS). Unexpectedly, this sensitivity corresponds with Stn1 OP blocking most, if not all, aspects of the S phase checkpoint. The checkpoint kinase Rad53 is phosphorylated with normal timing in Stn1 OP cells, indicating Stn1 does not interfere with signaling steps involved in activating the checkpoint. Part of the role of Stn1 in telomere integrity is mediated through the Pol12 subunit of DNA polymerase alpha (Pol alpha). We show that overproduced Stn1 generally associates with chromosomes in HU treated and untreated cells, and, remarkably, Stn1 chromosome binding and OP checkpoint defects are rescued in pol12 mutants. We propose Stn1 normally promotes Pol alpha activity at telomeres but can be recruited through Pol12 to nontelomeric sites when overproduced. During replication stress, the mislocalized Stn1 may inappropriately promote Pol alpha in a manner that interferes with Rad53 effector mechanisms controlling replication fork integrity.

SUBMITTER: Gasparyan HJ

PROVIDER: S-EPMC2650133 | biostudies-literature | 2009 Feb

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Yeast telomere capping protein Stn1 overrides DNA replication control through the S phase checkpoint.

Gasparyan Hovik J HJ Xu Ling L Petreaca Ruben C RC Rex Alexandra E AE Small Vanessa Y VY Bhogal Neil S NS Julius Jeffrey A JA Warsi Tariq H TH Bachant Jeff J Aparicio Oscar M OM Nugent Constance I CI

Proceedings of the National Academy of Sciences of the United States of America 20090126 7

Telomere integrity is maintained through end-protection proteins that block nuclease degradation and prevent telomeres from being recognized as DNA breaks. Although less well understood, end protection proteins may also play a role in facilitating telomere replication. Here, we show that overproduction (OP) of the yeast telomere capping protein Stn1 makes cells highly sensitive to the replication inhibitors hydroxyurea (HU) and methyl-methane sulfonate (MMS). Unexpectedly, this sensitivity corre ...[more]

PMID: 19171895

Similar Datasets

Project description:BackgroundAlthough much is known about molecular mechanisms that prevent re-initiation of DNA replication on newly replicated DNA during a single cell cycle, knowledge is sparse regarding the regions that are most susceptible to re-replication when those mechanisms are bypassed and regarding the extents to which checkpoint pathways modulate re-replication. We used microarrays to learn more about these issues in wild-type and checkpoint-mutant cells of the fission yeast, Schizosaccharomyces pombe.ResultsWe found that over-expressing a non-phosphorylatable form of the replication-initiation protein, Cdc18 (known as Cdc6 in other eukaryotes), drove re-replication of DNA sequences genome-wide, rather than forcing high level amplification of just a few sequences. Moderate variations in extents of re-replication generated regions spanning hundreds of kilobases that were amplified (or not) approximately 2-fold more (or less) than average. However, these regions showed little correlation with replication origins used during S phase. The extents and locations of amplified regions in cells deleted for the checkpoint genes encoding Rad3 (ortholog of human ATR and budding yeast Mec1) and Cds1 (ortholog of human Chk2 and budding yeast Rad53) were similar to those in wild-type cells. Relatively minor but distinct effects, including increased re-replication of heterochromatic regions, were found specifically in cells lacking Rad3. These might be due to Cds1-independent roles for Rad3 in regulating re-replication and/or due to the fact that cells lacking Rad3 continued to divide during re-replication, unlike wild-type cells or cells lacking Cds1. In both wild-type and checkpoint-mutant cells, regions near telomeres were particularly susceptible to re-replication. Highly re-replicated telomere-proximal regions (50-100 kb) were, in each case, followed by some of the least re-replicated DNA in the genome.ConclusionThe origins used, and the extent of replication fork progression, during re-replication are largely independent of the replication and DNA-damage checkpoint pathways mediated by Cds1 and Rad3. The fission yeast pattern of telomere-proximal amplification adjacent to a region of under-replication has also been seen in the distantly-related budding yeast, which suggests that subtelomeric sequences may be a promising place to look for DNA re-replication in other organisms.

Dataset Information

Yeast telomere capping protein Stn1 overrides DNA replication control through the S phase checkpoint.

Publications

Yeast telomere capping protein Stn1 overrides DNA replication control through the S phase checkpoint.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets