Figure 5.

Molecular images illustrating hydrogen bonds (dashed lines) shared between different forms of G·A pairing: (a) the N3⋯N6 interaction common to m−W_II and m−M_I base-paired arrangements found respectively in a variant of the SAM-I riboswitch⁶⁴ and the complex of Escherichia coli ribosomal protein L25 with a 5S rRNA fragment;⁶⁵ (b) the respective N2⋯N1 associations in m−W_I and W−W pairs in the Leishmania donovani large ribosomal subunit⁶⁶ and the Saccharomyces cerevisiae 80S ribosome;⁶⁷ (c) the N2⋯N7, N1⋯OP2, and N2⋯OP2 hydrogen bonds respectively stabilizing W−M and m−M_II pairs in the central domain of the Thermus thermophilus 30S ribosomal subunit⁶⁸ and in the complex of the Thermus thermophilus 70S ribosome with hibernation factor pY;³⁶ (d) the respective paired association of 2′-hydroxyl groups, one from G and the other from A, adopted in m−m and m−W_I pairs within the complex of tetracycline with the U1052G-mutated 70S Escherichia coli ribosome.⁶⁹