The A-minor motifs in the decoding recognition process

The formation of A-minor motifs, mediated by adenines binding into the shallow/minor groove of stacked and helical Watson–Crick base pairs, is described. The conformations of the bacterial ribosomal decoding A site in various crystal structures are reviewed. The adenines A1492 and A1493 of the A site are seen either tucked in within the internal loop or bulging out and poised for interaction. This dynamic equilibrium contributes to the decoding process of the codon:anticodon base pairings. Aminoglycoside antibiotics lock the conformation of the A site in a single state with bulged-out adenines and thereby disrupt regulation of the decoding process.