Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
Raphaël Méheust
Innovative Genomics Institute, University of California, Berkeley, Berkeley, United States; Earth and Planetary Science, University of California, Berkeley, Berkeley, United States
Omer Ad
Department of Chemistry, Yale University, New Haven, United States
Department of Chemistry, University of California, Berkeley, Berkeley, United States; Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
Jillian F Banfield
Innovative Genomics Institute, University of California, Berkeley, Berkeley, United States; Earth and Planetary Science, University of California, Berkeley, Berkeley, United States; Environmental Science, Policy and Management, University of California Berkeley, Berkeley, United States
Department of Chemistry, University of California, Berkeley, Berkeley, United States; Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States; Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, United States
Using cryo-electron microscopy (cryo-EM), we determined the structure of the Escherichia coli 70S ribosome with a global resolution of 2.0 Å. The maps reveal unambiguous positioning of protein and RNA residues, their detailed chemical interactions, and chemical modifications. Notable features include the first examples of isopeptide and thioamide backbone substitutions in ribosomal proteins, the former likely conserved in all domains of life. The maps also reveal extensive solvation of the small (30S) ribosomal subunit, and interactions with A-site and P-site tRNAs, mRNA, and the antibiotic paromomycin. The maps and models of the bacterial ribosome presented here now allow a deeper phylogenetic analysis of ribosomal components including structural conservation to the level of solvation. The high quality of the maps should enable future structural analyses of the chemical basis for translation and aid the development of robust tools for cryo-EM structure modeling and refinement.
