Figure 2.

Pseudoknots and –1 ribosomal frameshifting. (A) Pseudoknots used for bulk frameshift assays and single-molecule studies. The pseudoknots contain stem 1 (red), loop 1 (yellow), stem 2 (blue), and loop 2 (green). All the mutants were made based on ΔU177. In mutant CCCGU, all base triples are disrupted (two in stem 1-loop 2 and three in stem 2-loop 1). In TeloWT, the single nucleotide bulge U177 in stem 2 is added. The directions of applied mechanical force by optical tweezers are shown with black arrows. (B) Correlation observed between bulk –1 frameshifting efficiency and average unfolding force. Error bars are standard deviations from bulk and single-molecule experiments. Adapted from Chen et al. 2009.