Functional analysis of yeast snoRNA and snRNA 3'-end formation mediated by uncoupling of cleavage and polyadenylation.
Many nuclear and nucleolar small RNAs are accumulated as nonpolyadenylated species and require 3'-end processing for maturation. Here, we show that several genes coding for box C/D and H/ACA snoRNAs and for the U5 and U2 snRNAs contain sequences in their 3' portions which direct cleavage of primary transcripts without being polyadenylated. Genetic analysis of yeasts with mutations in different components of the pre-mRNA cleavage and polyadenylation machinery suggests that this mechanism of 3"-end formation requires cleavage factor IA (CF IA) but not cleavage and polyadenylation factor activity. However, in vitro results indicate that other factors participate in the reaction besides CF IA. Sequence analysis of snoRNA genes indicated that they contain conserved motifs in their 3" noncoding regions, and mutational studies demonstrated their essential role in 3"-end formation. We propose a model in which CF IA functions in cleavage and polyadenylation of pre-mRNAs and, in combination with a different set of factors, in 3"-end formation of nonpolyadenylated polymerase II transcripts.
Morlando
Mariangela
M
Institut Pasteur Fondazione Cenci-Bolognetti, Department of Genetics and Molecular Biology, University La Sapienza, 00185 Rome, Italy.
Greco
Paolo
P
Dichtl
Bernhard
B
Fatica
Alessandro
A
Keller
Walter
W
Bozzoni
Irene
I
D001483:Base Sequence; D015825:Chromosomes, Fungal; D005656:Fungal Proteins / Q000378:metabolism; D005800:Genes, Fungal; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000378:metabolism; D026723:Polyadenylation; D026721:RNA 3' End Processing; D012322:RNA Precursors / Q000378:metabolism; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism*; D012342:RNA, Small Nuclear / Q000235:genetics; D020537:RNA, Small Nucleolar / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D039221:mRNA Cleavage and Polyadenylation Factors
D005656:Fungal Proteins; D009687:Nuclear Proteins; D012322:RNA Precursors; D012331:RNA, Fungal; D012342:RNA, Small Nuclear; D020537:RNA, Small Nucleolar; D029701:Saccharomyces cerevisiae Proteins; C405484:U2 small nuclear RNA; C405485:U5 small nuclear RNA; D039221:mRNA Cleavage and Polyadenylation Factors