Structure of the nuclear exosome captured on a maturing preribosome

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 exoso