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

Lookup NU author(s): Dr Claudia Schneider, Eileen Leung, Dr Jeremy Brown

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Abstract

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.


Publication metadata

Author(s): Schneider C, Leung E, Brown J, Tollervey D

Publication type: Article

Publication status: Published

Journal: Nucleic Acids Research

Year: 2009

Volume: 37

Issue: 4

Pages: 1127-1140

Date deposited: 06/04/2010

ISSN (print): 0305-1048

ISSN (electronic): 1362-4962

Publisher: Oxford University Press

URL: http://dx.doi.org/10.1093/nar/gkn1020

DOI: 10.1093/nar/gkn1020

PubMed id: 19129231

Notes: Biotechnology and Biological Sciences Research Council/United Kingdom Wellcome Trust/United Kingdom Research Support, Non-U.S. Gov't England


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