Abstract
In contrast to mRNAs, rRNAs are transcribed by RNA polymerase I or III and are not believed to be polyadenylated. Here we show that in Saccharomyces cerevisiae, at least a small fraction of rRNAs do have a poly(A) tail. The levels of polyadenylated rRNAs are dramatically increased in strains lacking the degradation function of Rrp6p, a component of the nuclear exosome. Pap1p, the poly(A) polymerase, is responsible for adenylating the rRNAs despite the fact that the rRNAs do not have a canonical polyadenylation signal. Polyadenylated rRNAs reside mainly within the nucleus and are in turn degraded. For at least one rRNA type, the polyadenylation preferentially occurs on the precursor rather than the mature product. The existence of polyadenylated rRNAs may reflect a quality-control mechanism of rRNA biogenesis.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Base Sequence
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Cell Nucleus / metabolism
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Exoribonucleases / genetics
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Exoribonucleases / metabolism
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Exosome Multienzyme Ribonuclease Complex
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Genes, Fungal
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In Situ Hybridization, Fluorescence
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Poly A / chemistry
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Poly A / genetics
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Poly A / metabolism*
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Polynucleotide Adenylyltransferase / genetics
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Polynucleotide Adenylyltransferase / metabolism
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RNA, Fungal / chemistry
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RNA, Fungal / genetics
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RNA, Fungal / metabolism*
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RNA, Ribosomal / chemistry
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RNA, Ribosomal / genetics
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RNA, Ribosomal / metabolism*
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Reverse Transcriptase Polymerase Chain Reaction
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / metabolism*
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Saccharomyces cerevisiae Proteins / genetics
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Saccharomyces cerevisiae Proteins / metabolism
Substances
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RNA, Fungal
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RNA, Ribosomal
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Saccharomyces cerevisiae Proteins
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poly(A) ribosomal RNA
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RNA, ribosomal, 25S
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Poly A
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PAP1 protein, S cerevisiae
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Polynucleotide Adenylyltransferase
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Exoribonucleases
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Exosome Multienzyme Ribonuclease Complex
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RRP6 protein, S cerevisiae