Yeast Exosome Mutants Accumulate 3′-Extended Polyadenylated Forms of U4 Small Nuclear RNA and Small Nucleolar RNAs Journal Article uri icon



  • ABSTRACT; ; The exosome is a protein complex consisting of a variety of 3′-to-5′ exonucleases that functions both in 3′-to-5′ trimming of rRNA precursors and in 3′-to-5′ degradation of mRNA. To determine additional exosome functions, we examined the processing of a variety of RNAs, including tRNAs, small nuclear RNAs (snRNAs), small nucleolar RNAs (snoRNAs), RNase P, RNase MRP, and SRP RNAs, and 5S rRNAs in mutants defective in either the core components of the exosome or in other proteins required for exosome function. These experiments led to three important conclusions. First, exosome mutants accumulate 3′-extended forms of the U4 snRNA and a wide variety of snoRNAs, including snoRNAs that are independently transcribed or intron derived. This finding suggests that the exosome functions in the 3′ end processing of these species. Second, in exosome mutants, transcripts for U4 snRNA and independently transcribed snoRNAs accumulate as 3′-extended polyadenylated species, suggesting that the exosome is required to process these 3′-extended transcripts. Third, processing of 5.8S rRNA, snRNA, and snoRNA by the exosome is affected by mutations of the nuclear proteins Rrp6p and Mtr4p, whereas mRNA degradation by the exosome required Ski2p and was not affected by mutations in; RRP6; or; MTR4; . This finding suggests that the cytoplasmic and nuclear forms of the exosome represent two functionally different complexes involved in distinct 3′-to-5′ processing and degradation reactions.;

publication date

  • January 15, 2000

Date in CU Experts

  • February 21, 2014 10:37 AM

Full Author List

  • van Hoof A; Lennertz P; Parker R

author count

  • 3

Other Profiles

International Standard Serial Number (ISSN)

  • 0270-7306

Electronic International Standard Serial Number (EISSN)

  • 1098-5549

Additional Document Info

start page

  • 441

end page

  • 452


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