Nop58p is a common component of the box C+D snoRNPs that is required for snoRNA stability.
Eukaryotic nucleoli contain a large family of box C+D small nucleolar RNA (snoRNA) species, all of which are associated with a common protein Nop1p/fibrillarin. Nop58p was identified in a screen for synthetic lethality with Nop1p and shown to be an essential nucleolar protein. Here we report that a Protein A-tagged version of Nop58p coprecipitates all tested box C+D snoRNAs and that genetic depletion of Nop58p leads to the loss of all tested box C+D snoRNAs. The box H+ACA class of snoRNAs are not coprecipitated with Nop58p, and are not codepleted. The yeast box C+D snoRNAs include two species, U3 and U14, that are required for the early cleavages in pre-rRNA processing. Consistent with this, Nop58p depletion leads to a strong inhibition of pre-rRNA processing and 18S rRNA synthesis. Unexpectedly, depletion of Nop58p leads to the accumulation of 3' extended forms of U3 and U24, showing that the protein is also involved in snoRNA synthesis. Nop58p is the second common component of the box C+D snoRNPs to be identified and the first to be shown to be required for the stability and for the synthesis of these snoRNAs.
Lafontaine
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Institute of Cell and Molecular Biology, The University of Edinburgh, Scotland. denis.lafontaine@ed.ac.uk
Tollervey
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D015152:Blotting, Northern; D002466:Cell Nucleolus / Q000235:genetics* / Q000378:metabolism; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics*; D008745:Methylation; D009687:Nuclear Proteins / Q000235:genetics*; D012322:RNA Precursors / Q000235:genetics; D012323:RNA Processing, Post-Transcriptional / Q000235:genetics; D012331:RNA, Fungal / Q000235:genetics; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D012342:RNA, Small Nuclear / Q000145:classification / Q000235:genetics*; D017411:Ribonucleoproteins, Small Nuclear / Q000235:genetics; D020718:Ribonucleoproteins, Small Nucleolar; D029701:Saccharomyces cerevisiae Proteins; D013205:Staphylococcal Protein A / Q000235:genetics / Q000276:immunology
D002868:Chromosomal Proteins, Non-Histone; D005656:Fungal Proteins; C064793:NOP1 protein, S cerevisiae; D009687:Nuclear Proteins; D012322:RNA Precursors; D012331:RNA, Fungal; D012337:RNA, Ribosomal, 18S; D012342:RNA, Small Nuclear; D017411:Ribonucleoproteins, Small Nuclear; D020718:Ribonucleoproteins, Small Nucleolar; D029701:Saccharomyces cerevisiae Proteins; D013205:Staphylococcal Protein A; C047458:fibrillarin