title: Pif1 removes a Rap1-dependent barrier to the strand displacement activity of DNA polymerase δ.
abstract: Using an in vitro reconstituted system in this work we provide direct evidence that the yeast repressor/activator protein 1 (Rap1), tightly bound to its consensus site, forms a strong non-polar barrier for the strand displacement activity of DNA polymerase δ. We propose that relief of inhibition may be mediated by the activity of an accessory helicase. To this end, we show that Pif1, a 5'-3' helicase, not only stimulates the strand displacement activity of Pol δ but it also allows efficient replication through the block, by removing bound Rap1 in front of the polymerase. This stimulatory activity of Pif1 is not limited to the displacement of a single Rap1 molecule; Pif1 also allows Pol δ to carry out DNA synthesis across an array of bound Rap1 molecules that mimics a telomeric DNA-protein assembly. This activity of Pif1 represents a novel function of this helicase during DNA replication.
authors.affiliation: Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO 63110, USA.
authors.forename: Katrina N
authors.initials: KN
authors.lastname: Koc
authors.affiliation: Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO 63110, USA.
authors.forename: Saurabh P
authors.initials: SP
authors.lastname: Singh
authors.affiliation: Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO 63110, USA.
authors.forename: Joseph L
authors.initials: JL
authors.lastname: Stodola
authors.affiliation: Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO 63110, USA.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Burgers
authors.affiliation: Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO 63110, USA galletto@biochem.wustl.edu.
authors.forename: Roberto
authors.initials: R
authors.lastname: Galletto
mesh_terms: D004247:DNA / Q000096:biosynthesis / Q000378:metabolism; D004265:DNA Helicases / Q000378:metabolism*; D004258:DNA Polymerase III / Q000378:metabolism*; D004261:DNA Replication; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D000089804:Shelterin Complex; D034501:Telomere-Binding Proteins / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: C440829:RAP1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D000089804:Shelterin Complex; D034501:Telomere-Binding Proteins; D014157:Transcription Factors; D004247:DNA; D004258:DNA Polymerase III; C085463:PIF1 protein, S cerevisiae; D004265:DNA Helicases; C410222:DNA2 protein, S cerevisiae