Pif1-family helicases cooperatively suppress widespread replication-fork arrest at tRNA genes

Joseph S. Osmundson, Jayashree Kumar, Rani Yeung, Duncan Smith

Research output: Contribution to journalArticle

Abstract

Saccharomyces cerevisiae expresses two Pif1-family helicases—Pif1 and Rrm3—which have been reported to play distinct roles in numerous nuclear processes. Here, we systematically characterized the roles of Pif1 helicases in replisome progression and lagging-strand synthesis in S. cerevisiae. We demonstrate that either Pif1 or Rrm3 redundantly stimulates strand displacement by DNA polymerase δ during lagging-strand synthesis. By analyzing replisome mobility in pif1 and rrm3 mutants, we show that Rrm3, with a partially redundant contribution from Pif1, suppresses widespread terminal arrest of the replisome at tRNA genes. Although both head-on and codirectional collisions induce replication-fork arrest at tRNA genes, head-on collisions arrest a higher proportion of replisomes. In agreement with this observation, we found that head-on collisions between tRNA transcription and replication are under-represented in the S. cerevisiae genome. We demonstrate that tRNA-mediated arrest is R-loop independent and propose that replisome arrest and DNA damage are mechanistically separable.

Original languageEnglish (US)
JournalNature Structural and Molecular Biology
DOIs
StateAccepted/In press - Dec 19 2016

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Transfer RNA
Saccharomyces cerevisiae
Head
Genes
DNA-Directed DNA Polymerase
DNA Damage
Genome

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

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Pif1-family helicases cooperatively suppress widespread replication-fork arrest at tRNA genes. / Osmundson, Joseph S.; Kumar, Jayashree; Yeung, Rani; Smith, Duncan.

In: Nature Structural and Molecular Biology, 19.12.2016.

Research output: Contribution to journalArticle

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