Coupling of 5S RNP rotation with maturation of functional centers during large ribosomal subunit assembly

• Published in: Nature communications Vol. 11; no. 1; p. 3751
• Main Authors: Micic, Jelena, Li, Yu, Wu, Shan, Wilson, Daniel, Tutuncuoglu, Beril, Gao, Ning, Woolford, John L.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 27-07-2020; Nature Publishing Group; Nature Portfolio
• Subjects: 101/28; 101/58; 38/70; 38/90; 631/337/470; 631/337/574/1789; 631/535/1258/1259; 82/1; 82/83; Anchoring; Assembling; Assembly; Composition; Cytoplasm; Docks; Domains; Helices; Humanities and Social Sciences; Maturation; multidisciplinary; Mutation; Nucleoli; Peptidyltransferase; Polypeptides; Protein composition; Protein structure; Proteins; Ribosomal subunits; Ribosomes; Rotation; rRNA 5S; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-020-17534-5

The protein composition and structure of assembling 60S ribosomal subunits undergo numerous changes as pre-ribosomes transition from the nucleolus to the nucleoplasm. This includes stable anchoring of the Rpf2 subcomplex containing 5S rRNA, rpL5, rpL11, Rpf2 and Rrs1, which initially docks onto the flexible domain V of rRNA at earlier stages of assembly. In this work, we tested the function of the C-terminal domain (CTD) of Rpf2 during these anchoring steps, by truncating this extension and assaying effects on middle stages of subunit maturation. The
rpf2Δ255-344
mutation affects proper folding of rRNA helices H68-70 during anchoring of the Rpf2 subcomplex. In addition, several assembly factors (AFs) are absent from pre-ribosomes or in altered conformations. Consequently, major remodeling events fail to occur: rotation of the 5S RNP, maturation of the peptidyl transferase center (PTC) and the nascent polypeptide exit tunnel (NPET), and export of assembling subunits to the cytoplasm.
As assembling 60S subunits transit from the nucleolus to the nucleoplasm, they undergo significant changes in protein composition and structure. Here, the authors provide a structural view of interconnected events during the middle steps of assembly that include the maturation of the central protuberance, the peptidyltransferase center and the nascent polypeptide exit tunnel.