Rrp47p is an exosome-associated protein required for the 3' processing of stable RNAs.
Related exosome complexes of 3'-->5' exonucleases are present in the nucleus and the cytoplasm. Purification of exosome complexes from whole-cell lysates identified a Mg(2+)-labile factor present in substoichiometric amounts. This protein was identified as the nuclear protein Yhr081p, the homologue of human C1D, which we have designated Rrp47p (for rRNA processing). Immunoprecipitation of epitope-tagged Rrp47p confirmed its interaction with the exosome and revealed its association with Rrp6p, a 3'-->5' exonuclease specific to the nuclear exosome fraction. Northern analyses demonstrated that Rrp47p is required for the exosome-dependent processing of rRNA and small nucleolar RNA (snoRNA) precursors. Rrp47p also participates in the 3' processing of U4 and U5 small nuclear RNAs (snRNAs). The defects in the processing of stable RNAs seen in rrp47-Delta strains closely resemble those of strains lacking Rrp6p. In contrast, Rrp47p is not required for the Rrp6p-dependent degradation of 3'-extended nuclear pre-mRNAs or the cytoplasmic 3'-->5' mRNA decay pathway. We propose that Rrp47p functions as a substrate-specific nuclear cofactor for exosome activity in the processing of stable RNAs.
Mitchell
Philip
P
Wellcome Trust Centre for Cell Biology, Institute for Cell and Molecular Biology, University of Edinburgh, Edinburgh EH9 3JR, United Kingdom. pmitch@holyrood.ed.ac.uk
Petfalski
Elisabeth
E
Houalla
Rym
R
Podtelejnikov
Alexandre
A
Mann
Matthias
M
Tollervey
David
D
D020413:3' Untranslated Regions; D017398:Alternative Splicing; D002467:Cell Nucleus / Q000378:metabolism; D005095:Exoribonucleases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D009154:Mutation; D012313:RNA / Q000378:metabolism*; D012322:RNA Precursors / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D012335:RNA, Ribosomal / Q000378:metabolism; D012340:RNA, Ribosomal, 5.8S / Q000378:metabolism; D012342:RNA, Small Nuclear / Q000096:biosynthesis; D020537:RNA, Small Nucleolar / Q000096:biosynthesis; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism
D020413:3' Untranslated Regions; D012322:RNA Precursors; D012335:RNA, Ribosomal; D012340:RNA, Ribosomal, 5.8S; D012342:RNA, Small Nuclear; D020537:RNA, Small Nucleolar; D029701:Saccharomyces cerevisiae Proteins; D012313:RNA; D005095:Exoribonucleases; C478358:Rrp47p protein, human