Cryptic pol II transcripts are degraded by a nuclear quality control pathway involving a new poly(A) polymerase.
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.
Wyers
Françoise
F
Equipe Labelisée La Ligue, Avenue de la Terrasse, 91190 Gif sur Yvette, Paris, France.
Rougemaille
Mathieu
M
Badis
Gwenaël
G
Rousselle
Jean-Claude
JC
Dufour
Marie-Elisabeth
ME
Boulay
Jocelyne
J
Régnault
Béatrice
B
Devaux
Frédéric
F
Namane
Abdelkader
A
Séraphin
Bertrand
B
Libri
Domenico
D
Jacquier
Alain
A
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
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