Break-induced replication promotes formation of lethal joint molecules dissolved by Srs2

Break-induced replication (BIR) is a DNA double-strand break repair pathway that leads to genomic instabilities similar to those observed in cancer. BIR proceeds by a migrating bubble where asynchrony between leading and lagging strand synthesis leads to accumulation of long single-stranded DNA (ssD...

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Bibliographic Details
Published in:Nature communications 2017-11, Vol.8 (1), p.1790-13, Article 1790
Main Authors: Elango, Rajula, Sheng, Ziwei, Jackson, Jessica, DeCata, Jenna, Ibrahim, Younis, Pham, Nhung T., Liang, Diana H., Sakofsky, Cynthia J., Vindigni, Alessandro, Lobachev, Kirill S., Ira, Grzegorz, Malkova, Anna
Format: Article
Language:English
Subjects:
631/208/211
631/337/1427
631/337/151
Biology
Cancer
Channeling
Chromosomes
Deoxyribonucleic acid
Dismantling
DNA
DNA biosynthesis
DNA damage
DNA repair
Double-strand break repair
Genomic instability
Humanities and Social Sciences
Intermediates
multidisciplinary
Mutagenesis
Mutation
Proteins
Replication
Science
Science (multidisciplinary)
Single-stranded DNA
Stability
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Summary:Break-induced replication (BIR) is a DNA double-strand break repair pathway that leads to genomic instabilities similar to those observed in cancer. BIR proceeds by a migrating bubble where asynchrony between leading and lagging strand synthesis leads to accumulation of long single-stranded DNA (ssDNA). It remains unknown how this ssDNA is prevented from unscheduled pairing with the template, which can lead to genomic instability. Here, we propose that uncontrolled Rad51 binding to this ssDNA promotes formation of toxic joint molecules that are counteracted by Srs2. First, Srs2 dislodges Rad51 from ssDNA preventing promiscuous strand invasions. Second, it dismantles toxic intermediates that have already formed. Rare survivors in the absence of Srs2 rely on structure-specific endonucleases, Mus81 and Yen1, that resolve toxic joint-molecules. Overall, we uncover a new feature of BIR and propose that tight control of ssDNA accumulated during this process is essential to prevent its channeling into toxic structures threatening cell viability. Break-induced replication (BIR) is a double-strand break repair pathway that can lead to genomic instability. Here the authors show that the absence of Srs2 helicase during BIR leads to uncontrolled binding of Rad51 to single-stranded DNA, which promotes the formation of toxic intermediates that need to be resolved by Mus81 or Yen1.
ISSN:2041-1723
2041-1723
DOI:10.1038/s41467-017-01987-2