Ribosomal frameshifting and transcriptional slippage: From genetic steganography and cryptography to adventitious use

Atkins, John F.; Loughran, Gary; Bhatt, Pramod R.; Firth, Andrew E.; Baranov, Pavel V.

Studies on the IBV-derived system pointed to dissociation of EF-G being the rate limiting step for the incorporation of the incoming amino acid in the −1 frame. In a dnaX-derived system, the stem-loop and SD sequence aid the formation of a paused intermediate where translocation is uncoupled from reverse-rotation and E-site tRNA departure. As E-site tRNA exits, leaving only the P-site tRNA in place, EF-G samples the ribosome multiple times during the extended pause state. EF-G sampling is concurrent with continued Lys tRNA sampling at the A-site while slippage occurs. EF-G then finally catalyzes reverse rotation of the ribosome, resolving the unusual intermediate state to resume elongation in the −1 frame (Figure 16 ).