Rlp7p is associated with 60S preribosomes, restricted to the granular component of the nucleolus, and required for pre-rRNA processing

O Gadal, D Strauss, E Petfalski, P E Gleizes, N Gas, D Tollervey, E Hurt

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Many analyses have examined subnucleolar structures in eukaryotic cells, but the relationship between morphological structures, pre-rRNA processing, and ribosomal particle assembly has remained unclear. Using a visual assay for export of the 60S ribosomal subunit, we isolated a ts-lethal mutation, rix9-1, which causes nucleolar accumulation of an Rp125p-eGFP reporter construct. The, mutation results in a single amino acid substitution (F176S) in Rlp7p, an essential nucleolar protein related to ribosomal protein Rpl7p. The rix9-1 (rlp7-1) mutation blocks the late pre-RNA cleavage at site C-2 in ITS2, which separates the precursors to the 5.8S and 25S rRNAs. Consistent with this, synthesis of the mature 5.8S and 25S rRNAs was blocked in the rlp7-1 strain at nonpermissive temperature, whereas 18S rRNA synthesis continued. Moreover, pre-rRNA containing ITS2 accumulates in the nucleolus of rix9-1 cells as revealed by in situ hybridization. Finally, tagged Rlp7p was shown to associate with a pre-60S particle, and fluorescence microscopy and immuno-EM localized Rlp7p to a subregion of the nucleolus, which could be the granular component (GC). All together, these data suggest that pre-rRNA cleavage at site C2 specifically requires Rlp7p and occurs within pre-60S particles located in the GC region of the nucleolus.

Original languageEnglish
Pages (from-to)941-951
Number of pages11
JournalJournal of Cell Biology
Volume157
Issue number6
DOIs
Publication statusPublished - 10 Jun 2002

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