The structure of Rpf2-Rrs1 explains its role in ribosome biogenesis

• Published in: Nucleic acids research 2015-08, Vol.43 (14), p.7083-7095
• Main Authors: Kharde, Satyavati, Calviño, Fabiola R, Gumiero, Andrea, Wild, Klemens, Sinning, Irmgard
• Format: Article
• Language: English
• Subjects: Aspergillus nidulans; Fungal Proteins - chemistry; Fungal Proteins - metabolism; Fungal Proteins - physiology; Models, Molecular; Protein Binding; Protein Structure, Tertiary; Ribonucleoproteins - metabolism; Ribosomal Proteins - metabolism; Ribosome Subunits, Large, Eukaryotic - chemistry; Ribosome Subunits, Large, Eukaryotic - metabolism; RNA, Ribosomal, 5S - metabolism; RNA-Binding Proteins - chemistry; RNA-Binding Proteins - metabolism; RNA-Binding Proteins - physiology; Structural Biology
• ISSN: 0305-1048; 1362-4962
• DOI: 10.1093/nar/gkv640

The assembly of eukaryotic ribosomes is a hierarchical process involving about 200 biogenesis factors and a series of remodeling steps. The 5S RNP consisting of the 5S rRNA, RpL5 and RpL11 is recruited at an early stage, but has to rearrange during maturation of the pre-60S ribosomal subunit. Rpf2 and Rrs1 have been implicated in 5S RNP biogenesis, but their precise role was unclear. Here, we present the crystal structure of the Rpf2-Rrs1 complex from Aspergillus nidulans at 1.5 Å resolution and describe it as Brix domain of Rpf2 completed by Rrs1 to form two anticodon-binding domains with functionally important tails. Fitting the X-ray structure into the cryo-EM density of a previously described pre-60S particle correlates with biochemical data. The heterodimer forms specific contacts with the 5S rRNA, RpL5 and the biogenesis factor Rsa4. The flexible protein tails of Rpf2-Rrs1 localize to the central protuberance. Two helices in the Rrs1 C-terminal tail occupy a strategic position to block the rotation of 25S rRNA and the 5S RNP. Our data provide a structural model for 5S RNP recruitment to the pre-60S particle and explain why removal of Rpf2-Rrs1 is necessary for rearrangements to drive 60S maturation.