Reconstitution of the complete pathway of ITS2 processing at the pre-ribosome.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 29176610.
- Also identified by DOI 10.1038/s41467-017-01786-9 and PMC identifier 5702609.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Removal of internal transcribed spacer 2 (ITS2) from pre-ribosomal RNA is essential to make functional ribosomes. This complicated processing reaction begins with a single endonucleolytic cleavage followed by exonucleolytic trimming at both new cleavage sites to generate mature 5.8S and 25S rRNA. We reconstituted the 7S→5.8S processing branch within ITS2 using purified exosome and its nuclear cofactors. We find that both Rrp44's ribonuclease activities are required for initial RNA shortening followed by hand over to the exonuclease Rrp6. During the in vitro reaction, ITS2-associated factors dissociate and the underlying 'foot' structure of the pre-60S particle is dismantled. 7S pre-rRNA processing is independent of 5S RNP rotation, but 26S→25S trimming is a precondition for subsequent 7S→5.8S processing. To complete the in vitro assay, we reconstituted the entire cycle of ITS2 removal with a total of 18 purified factors, catalysed by the integrated activities of the two participating RNA-processing machines, the Las1 complex and nuclear exosome.
Medical subject headings
- RNA Precursors
- RNA Processing, Post-Transcriptional
- Ribosomal Proteins
- Ribosomes
- Saccharomyces cerevisiae