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Yeast Sen1 helicase protects the genome from transcription-associated instability.

Sen1 of S. cerevisiae is a known component of the NRD complex implicated in transcription termination of nonpolyadenylated as well as some polyadenylated RNA polymerase II transcripts. We now show that Sen1 helicase possesses a wider function by restricting the occurrence of RNA:DNA hybrids that may naturally form during transcription, when nascent RNA hybridizes to DNA prior to its packaging into RNA protein complexes. These hybrids displace the nontranscribed strand and create R loop structures. Loss of Sen1 results in transient R loop accumulation and so elicits transcription-associated recombination. SEN1 genetically interacts with DNA repair genes, suggesting that R loop resolution requires proteins involved in homologous recombination. Based on these findings, we propose that R loop formation is a frequent event during transcription and a key function of Sen1 is to prevent their accumulation and associated genome instability.

Pubmed ID: 21211720


  • Mischo HE
  • Gómez-González B
  • Grzechnik P
  • Rondón AG
  • Wei W
  • Steinmetz L
  • Aguilera A
  • Proudfoot NJ


Molecular cell

Publication Data

January 7, 2011

Associated Grants

  • Agency: Wellcome Trust, Id:

Mesh Terms

  • DNA Damage
  • DNA Helicases
  • DNA Repair
  • Genomic Instability
  • Nucleic Acid Conformation
  • Nucleic Acid Hybridization
  • Protein Structure, Tertiary
  • RNA Helicases
  • Recombination, Genetic
  • Saccharomyces cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Transcription, Genetic