Structural Visualization of the Formation and Activation of the 50S Ribosomal Subunit during In Vitro Reconstitution.
Nikolay, R., Hilal, T., Qin, B., Mielke, T., Burger, J., Loerke, J., Textoris-Taube, K., Nierhaus, K.H., Spahn, C.M.T.(2018) Mol Cell 70: 881-893.e3
- PubMed: 29883607 
- DOI: https://doi.org/10.1016/j.molcel.2018.05.003
- Primary Citation of Related Structures:  
6GBZ, 6GC0, 6GC4, 6GC6, 6GC7, 6GC8 - PubMed Abstract: 
The assembly of ribosomal subunits is an essential prerequisite for protein biosynthesis in all domains of life. Although biochemical and biophysical approaches have advanced our understanding of ribosome assembly, our mechanistic comprehension of this process is still limited. Here, we perform an in vitro reconstitution of the Escherichia coli 50S ribosomal subunit. Late reconstitution products were subjected to high-resolution cryo-electron microscopy and multiparticle refinement analysis to reconstruct five distinct precursors of the 50S subunit with 4.3-3.8 Å resolution. These assembly intermediates define a progressive maturation pathway culminating in a late assembly particle, whose structure is more than 96% identical to a mature 50S subunit. Our structures monitor the formation and stabilization of structural elements in a nascent particle in unprecedented detail and identify the maturation of the rRNA-based peptidyl transferase center as the final critical step along the 50S assembly pathway.
Organizational Affiliation: 
Institut für Medizinische Physik und Biophysik, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.