Depletion of yeast RNase III blocks correct U2 3' end formation and results in polyadenylated but functional U2 snRNA.
Yeast U2 snRNA is transcribed by RNA polymerase II to generate a single non-polyadenylated transcript. A temperature-sensitive yeast strain carrying a disruption in RNT1, the gene encoding a homolog of RNase III, produces 3'-extended U2 that is polyadenylated. The U2 3'-flanking region contains a putative stem-loop that is recognized and cleaved at two sites by recombinant GST-Rnt1 protein in vitro. Removal of sequences comprising the stem-loop structure blocks cleavage in vitro and mimics the effects of Rnt1 depletion in vivo. Strains carrying a U2 gene lacking the Rnt1 cleavage site produce only polyadenylated U2 snRNA, and yet are not impaired in growth or splicing. The results suggest that eukaryotic RNase III may be a general factor in snRNA processing, and demonstrate that polyadenylation is not incompatible with snRNA function in yeast.
Abou Elela
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Center for the Molecular Biology of RNA, Biology Department, Sinsheimer Laboratories, University of California at Santa Cruz, Santa Cruz, CA 95064, USA. sabou@courrier.usherb.ca
Ares
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D001483:Base Sequence; D002455:Cell Division; D004722:Endoribonucleases / Q000235:genetics / Q000378:metabolism*; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009690:Nucleic Acid Conformation; D011061:Poly A; D012326:RNA Splicing; D012331:RNA, Fungal / Q000737:chemistry; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D043244:Ribonuclease III; D017413:Ribonucleoprotein, U2 Small Nuclear / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D013329:Structure-Activity Relationship
D012331:RNA, Fungal; D011993:Recombinant Fusion Proteins; D017413:Ribonucleoprotein, U2 Small Nuclear; D029701:Saccharomyces cerevisiae Proteins; D011061:Poly A; D005982:Glutathione Transferase; D004722:Endoribonucleases; C468367:RNT1 protein, S cerevisiae; D043244:Ribonuclease III