title: Pif1-family helicases cooperatively suppress widespread replication-fork arrest at tRNA genes.
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.
authors.affiliation: Department of Biology, New York University, New York, New York, USA.
authors.forename: Joseph S
authors.initials: JS
authors.lastname: Osmundson
authors.affiliation: Department of Biology, New York University, New York, New York, USA.
authors.forename: Jayashree
authors.initials: J
authors.lastname: Kumar
authors.affiliation: Department of Biology, New York University, New York, New York, USA.
authors.forename: Rani
authors.initials: R
authors.lastname: Yeung
authors.affiliation: Department of Biology, New York University, New York, New York, USA.
authors.forename: Duncan J
authors.identifier: 0000-0002-0898-8629
authors.initials: DJ
authors.lastname: Smith
mesh_terms: D004247:DNA; D004265:DNA Helicases / Q000502:physiology*; D004261:DNA Replication; D054856:G-Quadruplexes; D005800:Genes, Fungal; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism; D012343:RNA, Transfer / Q000235:genetics* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000502:physiology*; D014158:Transcription, Genetic
chemical_list: C022262:Okazaki fragments; D012331:RNA, Fungal; D029701:Saccharomyces cerevisiae Proteins; D004247:DNA; D012343:RNA, Transfer; C085463:PIF1 protein, S cerevisiae; C459081:Rrm3 protein, S cerevisiae; D004265:DNA Helicases