title: Cryptic pol II transcripts are degraded by a nuclear quality control pathway involving a new poly(A) polymerase.
abstract: Since detection of an RNA molecule is the major criterion to define transcriptional activity, the fraction of the genome that is expressed is generally considered to parallel the complexity of the transcriptome. We show here that several supposedly silent intergenic regions in the genome of S. cerevisiae are actually transcribed by RNA polymerase II, suggesting that the expressed fraction of the genome is higher than anticipated. Surprisingly, however, RNAs originating from these regions are rapidly degraded by the combined action of the exosome and a new poly(A) polymerase activity that is defined by the Trf4 protein and one of two RNA binding proteins, Air1p or Air2p. We show that such a polyadenylation-assisted degradation mechanism is also responsible for the degradation of several Pol I and Pol III transcripts. Our data strongly support the existence of a posttranscriptional quality control mechanism limiting inappropriate expression of genetic information.
authors.affiliation: Equipe Labelisée La Ligue, Avenue de la Terrasse, 91190 Gif sur Yvette, Paris, France.
authors.forename: Françoise
authors.initials: F
authors.lastname: Wyers
authors.forename: Mathieu
authors.initials: M
authors.lastname: Rougemaille
authors.forename: Gwenaël
authors.initials: G
authors.lastname: Badis
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Rousselle
authors.forename: Marie-Elisabeth
authors.initials: ME
authors.lastname: Dufour
authors.forename: Jocelyne
authors.initials: J
authors.lastname: Boulay
authors.forename: Béatrice
authors.initials: B
authors.lastname: Régnault
authors.forename: Frédéric
authors.initials: F
authors.lastname: Devaux
authors.forename: Abdelkader
authors.initials: A
authors.lastname: Namane
authors.forename: Bertrand
authors.initials: B
authors.lastname: Séraphin
authors.forename: Domenico
authors.initials: D
authors.lastname: Libri
authors.forename: Alain
authors.initials: A
authors.lastname: Jacquier
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism*; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism; D005095:Exoribonucleases / Q000235:genetics / Q000378:metabolism; D063326:Exosome Multienzyme Ribonuclease Complex; D011062:Polynucleotide Adenylyltransferase / Q000378:metabolism*; D012313:RNA / Q000378:metabolism*; D012319:RNA Polymerase II / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C415824:Air1 protein, S cerevisiae; C415825:Air2 protein, S cerevisiae; D002352:Carrier Proteins; D029701:Saccharomyces cerevisiae Proteins; D012313:RNA; D012319:RNA Polymerase II; D011062:Polynucleotide Adenylyltransferase; D004259:DNA-Directed DNA Polymerase; C487545:PAP2 protein, S cerevisiae; D005095:Exoribonucleases; D063326:Exosome Multienzyme Ribonuclease Complex; C112610:RRP6 protein, S cerevisiae