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A Checkpoint-Related Function of the MCM Replicative Helicase Is Required to Avert Accumulation of RNA:DNA Hybrids during S-phase and Ensuing DSBs during G2/M

Jinks-Robertson, Sue and Vijayraghavan, Sriram and Tsai, Feng-Ling and Schwacha, Anthony (2016) A Checkpoint-Related Function of the MCM Replicative Helicase Is Required to Avert Accumulation of RNA:DNA Hybrids during S-phase and Ensuing DSBs during G2/M. PLOS Genetics, 12 (8). e1006277. ISSN 1553-7404

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Abstract

The Mcm2-7 complex is the catalytic core of the eukaryotic replicative helicase. Here, we identify a new role for this complex in maintaining genome integrity. Using both genetic and cytological approaches, we find that a specific mcm allele (mcm2DENQ) causes elevated genome instability that correlates with the appearance of numerous DNA-damage associated foci of γH2AX and Rad52. We further find that the triggering events for this genome instability are elevated levels of RNA:DNA hybrids and an altered DNA topological state, as over-expression of either RNaseH (an enzyme specific for degradation of RNA in RNA:DNA hybrids) or Topoisomerase 1 (an enzyme that relieves DNA supercoiling) can suppress the mcm2DENQ DNA-damage phenotype. Moreover, the observed DNA damage has several additional unusual properties, in that DNA damage foci appear only after S-phase, in G2/M, and are dependent upon progression into metaphase. In addition, we show that the resultant DNA damage is not due to spontaneous S-phase fork collapse. In total, these unusual mcm2DENQ phenotypes are markedly similar to those of a special previously-studied allele of the checkpoint sensor kinase ATR/MEC1, suggesting a possible regulatory interplay between Mcm2-7 and ATR during unchallenged growth. As RNA:DNA hybrids primarily result from transcription perturbations, we suggest that surveillance-mediated modulation of the Mcm2-7 activity plays an important role in preventing catastrophic conflicts between replication forks and transcription complexes. Possible relationships among these effects and the recently discovered role of Mcm2-7 in the DNA replication checkpoint induced by HU treatment are discussed.


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Details

Item Type: Article
Status: Published
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Jinks-Robertson, Sue
Vijayraghavan, Sriram
Tsai, Feng-Ling
Schwacha, Anthonyschwacha@pitt.edu
Date: 24 August 2016
Date Type: Publication
Journal or Publication Title: PLOS Genetics
Volume: 12
Number: 8
Publisher: Public Library of Science (PLoS)
Page Range: e1006277
DOI or Unique Handle: 10.1371/journal.pgen.1006277
Schools and Programs: Dietrich School of Arts and Sciences > Biological Sciences
Refereed: Yes
ISSN: 1553-7404
Official URL: https://doi.org/10.1371/journal.pgen.1006277
Article Type: Research Article
Date Deposited: 13 May 2020 16:38
Last Modified: 13 May 2020 16:38
URI: http://d-scholarship.pitt.edu/id/eprint/38934

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