Base pairing between U3 and the pre-ribosomal RNA is required for 18S rRNA synthesis

M. Beltrame*, D. Tollervey

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The nucleolus, the site of pre-ribosomal RNA (pre-rRNA) synthesis and processing in eukaryotic cells, contains a number of small nucleolar RNAs (snoRNAs). Yeast U3 snoRNA is required for the processing of 18S rRNA from larger precursors and contains a region complementary to the pre-rRNA. Substitution mutations in the pre-rRNA which disrupt this base pairing potential are lethal and prevent synthesis of 18S rRNA. These mutant pre-rRNAs show defects in processing which closely resemble the effects of genetic depletion of components of the U3 snoRNP. Co-expression of U3 snoRNAs which carry compensatory mutations allows the mutant pre-rRNAs to support viability and synthesize 18S rRNA at high levels. Pre-rRNA processing steps which are blocked by the external transcribed spacer region mutations are largely restored by expression of the compensatory U3 mutants. Pre-rRNA processing therefore requires direct base pairing between snoRNA and the substrate. Base pairing with the substrate is thus a common feature of small RNAs involved in mRNA and rRNA maturation.

Original languageEnglish
Pages (from-to)4350-4356
Number of pages7
JournalEMBO Journal
Issue number17
Publication statusPublished - 1 Sep 1995


  • ribosomes
  • RNA
  • RNA processing
  • small nucleolar RNAs
  • U3


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