Fig 1. A brief introduction of RlmCD and its RNA substrates.

(A) Schematic illustration of the full-length RlmCD. (B, C) Primary sequences and secondary structures of RNA segments analogous to U747 and U1939 sites of S. pneumoniae 23S rRNA. The nucleotides in red represent the methylation target (U747 or U1939) of RlmCD in the RNA segments while the nucleotides in blue are 743–754 base-pair which were mutated from original A-U to G-C to increase the conformational stability of U747_SL.