The N-terminal PIN domain of the exosome subunit Rrp44 harbors endonuclease activity and tethers Rrp44 to the yeast core exosome

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  2. Dr Claudia Schneider
  3. Eileen Leung
  4. Dr Jeremy Brown
Author(s)Schneider C, Leung E, Brown J, Tollervey D
Publication type Article
JournalNucleic Acids Research
Year2009
Volume37
Issue4
Pages1127-1140
ISSN (print)0305-1048
ISSN (electronic)1362-4962
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Nuclear and cytoplasmic forms of the yeast exosome share 10 components, of which only Rrp44/Dis3 is believed to possess 3' exonuclease activity. We report that expression only of Rrp44 lacking 3'-exonuclease activity (Rrp44-exo) supports growth in S288c-related strains (BY4741). In BY4741, rrp44-exo was synthetic-lethal with loss of the cytoplasmic 5'-exonuclease Xrn1, indicating block of mRNA turnover, but not with loss of the nuclear 3'-exonuclease Rrp6. The RNA processing phenotype of rrp44-exo was milder than that seen on Rrp44 depletion, indicating that Rrp44-exo retains important functions. Recombinant Rrp44 was shown to possess manganese-dependent endonuclease activity in vitro that was abolished by four point mutations in the putative metal binding residues of its N-terminal PIN domain. Rrp44 lacking both exonuclease and endonuclease activity failed to support growth in strains depleted of endogenous Rrp44. Strains expressing Rrp44-exo and Rrp44-endo-exo exhibited different RNA processing patterns in vivo suggesting Rrp44-dependent endonucleolytic cleavages in the 5'-ETS and ITS2 regions of the pre-rRNA. Finally, the N-terminal PIN domain was shown to be necessary and sufficient for association with the core exosome, indicating its dual function as a nuclease and structural element.
PublisherOxford University Press
URLhttp://dx.doi.org/10.1093/nar/gkn1020
DOI10.1093/nar/gkn1020
PubMed id19129231
NotesBiotechnology and Biological Sciences Research Council/United Kingdom Wellcome Trust/United Kingdom Research Support, Non-U.S. Gov't England
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