FIGURE 4.
Model for pseudoknot plasticity during translation. Prior to encountering the ribosome, the frameshifting pseudoknot adopts multiple conformations. The pseudoknot structure determined by cryo-EM (Zhang et al. 2021) contains an additional helix (red) from nts 13,459–73, which includes the upstream slippery site and is absent from the coaxially stacked pseudoknot structure presented herein. As the ribosome proceeds past the slippery site, the fully stacked conformation may be favored.
