Article
- The EMBO Journal (1999) 18, 5399 - 5410
- doi:10.1093/emboj/18.19.5399
Functions of the exosome in rRNA, snoRNA and snRNA synthesis
Christine Allmang1,4, Joanna Kufel1,4, Guillaume Chanfreau2,3, Philip Mitchell1, Elisabeth Petfalski1 and David Tollervey1
- Institute of Cell and Molecular Biology, University of Edinburgh, Swann Building, King's Buildings, Edinburgh EH9 3JR, UK
- GIM-Biotechnologies, Institut Pasteur, 25 rue du Dr Roux, 75724 Paris Cedex 15, France
- Present address: Department of Chemistry and Biochemistry, UCLA, Los Angeles CA 90095-1569, USA
- C.Allmang and J.Kufel contributed equally to this work
Correspondence to:
David Tollervey, E-mail: d.tollervey@ed.ac.uk
Received 24 June 1999; Accepted 10 August 1999; Revised 10 August 1999
Abstract
The yeast nuclear exosome contains multiple 3'
5' exoribonucleases, raising the question of why so many activities are present in the complex. All components are required during the 3' processing of the 5.8S rRNA, together with the putative RNA helicase Dob1p/Mtr4p. During this processing three distinct steps can be resolved, and hand-over between different exonucleases appears to occur at least twice. 3' processing of snoRNAs (small nucleolar RNAs) that are excised from polycistronic precursors or from mRNA introns is also a multi-step process that involves the exosome, with final trimming specifically dependent on the Rrp6p component. The spliceosomal U4 snRNA (small nuclear RNA) is synthesized from a 3' extended precursor that is cleaved by Rnt1p at sites 135 and 169 nt downstream of the mature 3' end. This cleavage is followed by 3'5' processing of the pre-snRNA involving the exosome complex and Dob1p. The exosome, together with Rnt1p, also participates in the 3' processing of the U1 and U5 snRNAs. We conclude that the exosome is involved in the processing of many RNA substrates and that different components can have distinct functions.
Keywords:
- pre-rRNA,
- RNA processing,
- Saccharomyces cerevisiae,
- snoRNA,
- snRNA
