Figure 2.

The ligand-dependent co-transcriptional folding behaviors of the pbuE riboswitch. The population kinetics of main structures from step 60 under different transcription conditions are shown: 20 nt/s, 0 µM adenine (a); 20 nt/s, 100 µM adenine (b); 50 nt/s, 100 µM adenine (c); 50 nt/s, 100 µM adenine with pausing (60 s) at step 67 (d). The superscript “b” denotes the corresponding state with the ligand bound and C^b denotes the ensemble of all the bound states. Main co-transcriptional folding pathways and folding events are mapped in (e). T is the terminator hairpin; L is the ligand (adenine). Nucleotides within paired regions of the aptamer structure are colored differently.