The role of the putative 3' end processing endonuclease Ysh1p in mRNA and snoRNA synthesis.
Pre-mRNA 3' end formation is tightly linked to upstream and downstream events of eukaryotic mRNA synthesis. The two-step reaction involves endonucleolytic cleavage of the primary transcript followed by poly(A) addition to the upstream cleavage product. To further characterize the putative 3' end processing endonuclease Ysh1p/Brr5p, we isolated and analyzed a number of new temperature- and cold-sensitive mutant alleles. We show that Ysh1p plays a crucial role in 3' end formation and in RNA polymerase II (RNAP II) transcription termination on mRNA genes. In addition, we observed a range of additional functional deficiencies in ysh1 mutant strains, which were partially allele-specific. Interestingly, snoRNA 3' end formation and RNAP II termination were defective on specific snoRNAs in the cold-sensitive ysh1-12 strain. Moreover, we observed the accumulation of several mRNAs including the NRD1 transcript in this mutant. We provide evidence that NRD1 autoregulation is associated with endonucleolytic cleavage and that this process may involve Ysh1p. In addition, the ysh1-12 strain displayed defects in RNA splicing indicating that a functional link may exist between intron removal and 3' end formation in yeast. These observations suggest that Ysh1p has multiple roles in RNA synthesis and processing.
Garas
Monika
M
Biozentrum, University of Basel, CH-4056 Basel, Switzerland.
Dichtl
Bernhard
B
Keller
Walter
W
D004720:Endonucleases / Q000378:metabolism; D026723:Polyadenylation; D012319:RNA Polymerase II / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D012326:RNA Splicing; D012331:RNA, Fungal / Q000378:metabolism; D012333:RNA, Messenger; D020537:RNA, Small Nucleolar / Q000378:metabolism*; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D039221:mRNA Cleavage and Polyadenylation Factors / Q000378:metabolism*
C491211:NRD1 protein, S cerevisiae; D012331:RNA, Fungal; D012333:RNA, Messenger; D020537:RNA, Small Nucleolar; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; D029701:Saccharomyces cerevisiae Proteins; C450401:YSH1 protein, S cerevisiae; D039221:mRNA Cleavage and Polyadenylation Factors; D012319:RNA Polymerase II; D004720:Endonucleases