Distinct pathways for snoRNA and mRNA termination.
Transcription termination at mRNA genes is linked to polyadenylation. Cleavage at the poly(A) site generates an entry point for the Rat1/Xrn2 exonuclease, which degrades the downstream transcript to promote termination. Small nucleolar RNAs (snoRNAs) are also transcribed by RNA polymerase II but are not polyadenylated. Chromatin immunoprecipitation experiments show that polyadenylation factors and Rat1 localize to snoRNA genes, but mutations that disrupt poly(A) site cleavage or Rat1 activity do not lead to termination defects at these genes. Conversely, mutations of Nrd1, Sen1, and Ssu72 affect termination at snoRNAs but not at several mRNA genes. The exosome complex was required for 3' trimming, but not termination, of snoRNAs. Both the mRNA and snoRNA pathways require Pcf11 but show differential effects of individual mutant alleles. These results suggest that in yeast the transcribing RNA polymerase II can choose between two distinct termination mechanisms but keeps both options available during elongation.
Kim
Minkyu
M
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115.
Vasiljeva
Lidia
L
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115.
Rando
Oliver J
OJ
Bauer Center for Genomics Research, Harvard University, 7 Divinity Avenue, Cambridge, Massachusetts 02138.
Zhelkovsky
Alexander
A
Department of Molecular Microbiology, Tufts University School of Medicine, 136 Harrison Avenue, Boston, Massachusetts 02111.
Moore
Claire
C
Department of Molecular Microbiology, Tufts University School of Medicine, 136 Harrison Avenue, Boston, Massachusetts 02111.
Buratowski
Stephen
S
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115. Electronic address: steveb@hms.harvard.edu.
D015152:Blotting, Northern; D047369:Chromatin Immunoprecipitation; D004265:DNA Helicases; D004257:DNA Polymerase II / Q000378:metabolism; D005095:Exoribonucleases / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D020365:RNA Helicases; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D020537:RNA, Small Nucleolar / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism; D012261:Ribonucleoproteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
D005656:Fungal Proteins; C090564:NAB3 protein, S cerevisiae; C491211:NRD1 protein, S cerevisiae; D009687:Nuclear Proteins; D012333:RNA, Messenger; D020537:RNA, Small Nucleolar; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; D029701:Saccharomyces cerevisiae Proteins; C075577:RAT1 protein, S cerevisiae; D004257:DNA Polymerase II; D005095:Exoribonucleases; C542347:SEN1 protein, S cerevisiae; D004265:DNA Helicases; D020365:RNA Helicases