FIGURE 2.
Primer-based SHAPE-MaP informed secondary structure of the SreA aptamer. Primer-based MaP of the SHAPE modified of the SreA Aptamer construct produced two competing models with comparable pseudo-free energies. Structure 1 (left) is consistent with the expected SAM-I riboswitch aptamer domain secondary structure, containing a four-way junction with well-folded P1–4 helices. Structure 2 (right) is characterized by an elongated P3 helix that incorporates portions of the P2 helix and adjacent junction. Secondary structures are numbered based on the native SreA Aptamer domain (nt 0–116).
