Pif1 family DNA helicases: A helpmate to RNase H?

Thomas J. Pohl, Virginia A. Zakian

Research output: Contribution to journalReview articlepeer-review

21 Scopus citations


An R-loop is a structure that forms when an RNA transcript stays bound to the DNA strand that encodes it and leaves the complementary strand exposed as a loop of single stranded DNA. R-loops accumulate when the processing of RNA transcripts is impaired. The failure to remove these RNA-DNA hybrids can lead to replication fork stalling and genome instability. Resolution of R-loops is thought to be mediated mainly by RNase H enzymes through the removal and degradation of the RNA in the hybrid. However, DNA helicases can also dismantle R-loops by displacing the bound RNA. In particular, the Pif1 family DNA helicases have been shown to regulate R-loop formation at specific genomic loci, such as tRNA genes and centromeres. Here we review the roles of Pif1 family helicases in vivo and in vitro and discuss evidence that Pif1 family helicases act on RNA-DNA hybrids and highlight their potential roles in complementing RNase H for R-loop resolution.

Original languageEnglish (US)
Article number102633
JournalDNA Repair
StatePublished - Dec 2019
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Biochemistry
  • Cell Biology


  • DNA
  • RNA
  • tRNA


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