Figure 3.

Mutations and modifications in the 23S rRNA related to linezolid resistance. (A) Secondary-structure model of part of the V domain of the 23S rRNA of S. pneumoniae. (Blue) Mutations in the 23S rRNA linked to linezolid resistance; (boxed residues) positions 2445, 2447, 2503, and 2576 found in this study; (red) new mutations or resistance mechanisms; (shaded) nucleotides that directly interact with linezolid as determined from several structural studies cited in the text. (B) Reverse transcription analysis of the S. pneumoniae 23S rRNA. U, A, C, G correspond with sequencing lanes. Primer extension results of the 23S rRNA from the control susceptible strain 1974 (lane 1), 1974M1 (lane 2), 1974M1 with pJF0333 (lane 3), 1974M1 with vector pDL289 (lane 4) are shown. The block (when present) in the reverse transcription reaction at position G2445 is indicated.