Biochemical characterization of the helicase Sen1 provides new insights into the mechanisms of non-coding transcription termination.
Pervasive transcription is widespread and needs to be controlled in order to avoid interference with gene expression. In Saccharomyces cerevisiae, the highly conserved helicase Sen1 plays a key role in restricting pervasive transcription by eliciting early termination of non-coding transcription. However, many aspects of the mechanism of termination remain unclear. In this study we characterize the biochemical activities of Sen1 and their role in termination. First, we demonstrate that the helicase domain (HD) is sufficient to dissociate the elongation complex (EC) in vitro. Both full-length Sen1 and its HD can translocate along single-stranded RNA and DNA in the 5΄ to 3΄ direction. Surprisingly, however, we show that Sen1 is a relatively poorly processive enzyme, implying that it must be recruited in close proximity to the RNA polymerase II (RNAPII) for efficient termination. We present evidence that Sen1 can promote forward translocation of stalled polymerases by acting on the nascent transcript. In addition, we find that dissociation of the EC by Sen1 is favoured by the reannealing of the DNA upstream of RNAPII. Taken together, our results provide new clues to understand the mechanism of Sen1-dependent transcription termination and a rationale for the kinetic competition between elongation and termination.
Institut Jacques Monod, UMR7592, Centre Nationale pour la Recherche Scientifique (CNRS), Université Paris-Diderot, Sorbonne Paris Cité, F-75205 Paris, France.|Université Paris-Saclay, 91190 Gif sur Yvette, France.
Zhong
Z
Han
Institut Jacques Monod, UMR7592, Centre Nationale pour la Recherche Scientifique (CNRS), Université Paris-Diderot, Sorbonne Paris Cité, F-75205 Paris, France.
Domenico
D
Libri
Institut Jacques Monod, UMR7592, Centre Nationale pour la Recherche Scientifique (CNRS), Université Paris-Diderot, Sorbonne Paris Cité, F-75205 Paris, France.
Odil
O
Porrua
D004265:DNA Helicases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000072417:Protein Domains; D020365:RNA Helicases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D012319:RNA Polymerase II / Q000378:metabolism; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D061806:Transcription Termination, Genetic
D004277:DNA, Single-Stranded; C090564:NAB3 protein, S cerevisiae; C491211:NRD1 protein, S cerevisiae; D009687:Nuclear Proteins; D012331:RNA, Fungal; D016601:RNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; D012319:RNA Polymerase II; C542347:SEN1 protein, S cerevisiae; D004265:DNA Helicases; D020365:RNA Helicases