Views of the cryo-EM maps around some anionic pairs based on the E. coli ribosome structure (7K00, Watson et al. 2020). (A) Map around the anionic G2304•U2312 pair in the 23S rRNA and its contacts with two conserved residues of protein uL5, N37, and D153. The nature of the amino acid side chain atoms in contact with G2304 and U2312 cannot be ascertained at this stage. The distance between the nitrogen atom of N37 and one of the oxygen atoms of D153 is 3.4 Å. Note also that the density for the carboxylate group is weak, which could be due to radiation damage (Marques et al. 2019). (B) Map around the anionic U677•G713 pair and A777 in the 16S rRNA. (C) Map around the anionic G664•G741 in E. coli. The water molecules bound to O4(G741) are above and below the plane of the base.
