Gene regulation by a glycine riboswitch singlet uses a finely tuned energetic landscape for helical switching

Heat maps. The mean Y_min (A), Y_max (B), and K_1/2 (C) values for the three variants at each nucleotide position were mapped onto the predicted secondary structure. Deleterious mutations highlight functionally relevant regions of the riboswitch. Variants with an amplitude of <15% were excluded when computing the K_1/2 mean values shown in C, as K_1/2 values for these mutants may be influenced by minor amounts of WT contamination (see Supplemental Text).