Dissecting mechanisms of nuclear mRNA surveillance in THO/sub2 complex mutants.

Mathieu Rougemaille, Rajani Kanth Gudipati, Jens Raabjerg Olesen, Rune Thomsen, Bertrand Seraphin, Domenico Libri, Torben Heick Jensen

    Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaperJournal articleResearchpeer-review

    113 Citations (Scopus)

    Abstract

    The nuclear exosome is involved in numerous RNA metabolic processes. Exosome degradation of rRNA, snoRNA, snRNA and tRNA in Saccharomyces cerevisiae is activated by TRAMP complexes, containing either the Trf4p or Trf5p poly(A) polymerase. These enzymes are presumed to facilitate exosome access by appending oligo(A)-tails onto structured substrates. Another role of the nuclear exosome is that of mRNA surveillance. In strains harboring a mutated THO/Sub2p system, involved in messenger ribonucleoprotein particle biogenesis and nuclear export, the exosome-associated 3' 5' exonuclease Rrp6p is required for both retention and degradation of nuclear restricted mRNAs. We show here that Trf4p, in the context of TRAMP, is an mRNA surveillance factor. However, unlike Rrp6p, Trf4p only partakes in RNA degradation and not in transcript retention. Surprisingly, a polyadenylation-defective Trf4p protein is fully active, suggesting polyadenylation-independent mRNA degradation. Transcription pulse–chase experiments show that HSP104 molecules undergoing quality control in THO/sub2 mutant strains fall into two distinct populations: One that is quickly degraded after transcription induction and another that escapes rapid decay and accumulates in foci associated with the HSP104 transcription site.
    Original languageEnglish
    JournalE M B O Journal
    Volume26
    Pages (from-to)2317-2326
    Number of pages10
    ISSN0261-4189
    DOIs
    Publication statusPublished - 5 Apr 2007

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