Figure 3.

2A3 successfully queries regions of the ribosome that are blind to other reagents. (A) Sample of SHAPE−MaP mutation frequencies for all tested compounds across a region spanning nucleotides 990 to 1162 of E. coli 23S rRNA. Colored bases are those whose mutation frequencies exceed by 2-fold the median mutation frequency in the analyzed region. The accepted structure is reported as an arc plot. The hyperreactive residue U₁₀₃₂ and the unreactive stretch of 19 nucleotides are respectively marked in red and blue. (B) Three-dimensional model of the domain depicted in A, colored by B factor (PDB: 5IT8). The inset zooms on the helical region containing the 2A3-hyperreactive residue U₁₀₃₂.