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Science. 2018 Apr 13;360(6385):219-222. doi: 10.1126/science.aar5428. Epub 2018 Mar 8.

Structure of the nuclear exosome captured on a maturing preribosome.

Author information

1
Department of Structural Cell Biology, Max Planck Institute (MPI) for Biochemistry, Munich, Germany.
2
Biochemistry Centre, University of Heidelberg, Heidelberg, Germany.
3
Biochemistry Centre, University of Heidelberg, Heidelberg, Germany. conti@biochem.mpg.de ed.hurt@bzh.uni-heidelberg.de.
4
Department of Structural Cell Biology, Max Planck Institute (MPI) for Biochemistry, Munich, Germany. conti@biochem.mpg.de ed.hurt@bzh.uni-heidelberg.de.

Abstract

The RNA exosome complex processes and degrades a wide range of transcripts, including ribosomal RNAs (rRNAs). We used cryo-electron microscopy to visualize the yeast nuclear exosome holocomplex captured on a precursor large ribosomal subunit (pre-60S) during 7S-to-5.8S rRNA processing. The cofactors of the nuclear exosome are sandwiched between the ribonuclease core complex (Exo-10) and the remodeled "foot" structure of the pre-60S particle, which harbors the 5.8S rRNA precursor. The exosome-associated helicase Mtr4 recognizes the preribosomal substrate by docking to specific sites on the 25S rRNA, captures the 3' extension of the 5.8S rRNA, and channels it toward Exo-10. The structure elucidates how the exosome forms a structural and functional unit together with its massive pre-60S substrate to process rRNA during ribosome maturation.

PMID:
29519915
DOI:
10.1126/science.aar5428
[Indexed for MEDLINE]

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