Molecular architecture of the 90S small subunit pre-ribosome
Qi Sun,
Xing Zhu,
Jia Qi,
Weidong An,
Pengfei Lan,
Dan Tan,
Rongchang Chen,
Bing Wang,
Sanduo Zheng,
Cheng Zhang,
Xining Chen,
Wei Zhang,
Jing Chen,
Meng-Qiu Dong,
Keqiong Ye
Affiliations
Qi Sun
PTN Joint Graduate Program, School of Life Sciences, Tsinghua University, Beijing, China; Key Laboratory of RNA Biology, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, Beijing, China; National Institute of Biological Sciences, Beijing, China
Key Laboratory of RNA Biology, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, Beijing, China
Jia Qi
Key Laboratory of RNA Biology, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, Beijing, China; National Institute of Biological Sciences, Beijing, China; Department of Biochemistry and Molecular Biology, College of Life Sciences, Beijing Normal University, Beijing, China
Weidong An
Key Laboratory of RNA Biology, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, Beijing, China; National Institute of Biological Sciences, Beijing, China; College of Biological Sciences, China Agricultural University, Beijing, China
Pengfei Lan
National Institute of Biological Sciences, Beijing, China
Dan Tan
National Institute of Biological Sciences, Beijing, China
Rongchang Chen
Key Laboratory of RNA Biology, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, Beijing, China
Bing Wang
Key Laboratory of RNA Biology, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, Beijing, China; National Institute of Biological Sciences, Beijing, China
Sanduo Zheng
National Institute of Biological Sciences, Beijing, China
Cheng Zhang
National Institute of Biological Sciences, Beijing, China
Xining Chen
National Institute of Biological Sciences, Beijing, China
Wei Zhang
National Institute of Biological Sciences, Beijing, China
Jing Chen
PTN Joint Graduate Program, School of Life Sciences, Tsinghua University, Beijing, China; Key Laboratory of RNA Biology, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, Beijing, China; National Institute of Biological Sciences, Beijing, China
Key Laboratory of RNA Biology, Institute of Biophysics, CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China
Eukaryotic small ribosomal subunits are first assembled into 90S pre-ribosomes. The complete 90S is a gigantic complex with a molecular mass of approximately five megadaltons. Here, we report the nearly complete architecture of Saccharomyces cerevisiae 90S determined from three cryo-electron microscopy single particle reconstructions at 4.5 to 8.7 angstrom resolution. The majority of the density maps were modeled and assigned to specific RNA and protein components. The nascent ribosome is assembled into isolated native-like substructures that are stabilized by abundant assembly factors. The 5' external transcribed spacer and U3 snoRNA nucleate a large subcomplex that scaffolds the nascent ribosome. U3 binds four sites of pre-rRNA, including a novel site on helix 27 but not the 3' side of the central pseudoknot, and crucially organizes the 90S structure. The 90S model provides significant insight into the principle of small subunit assembly and the function of assembly factors.
