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.

Despite its conservation, the stimulatory role for the Shine Dalgarno-like interaction by translating ribosomes on bacterial release factor 2 +1 frameshifting is deduced not to mask a role for the commonly encoded glycine since the sequence GG GGG is sometimes GG AGG which is also a good Shine Dalgarno type sequence but which does not encode glycine. Nevertheless, in the absence of a nascent peptide modulator and independent of mRNA:rRNA interaction stimulation, increasing polyamine levels, such as occur at the early logarithmic phase of growth, enhance release factor 2 frameshifting (481) . While polyamines preferentially enhance the levels of quite a number of proteins whose synthesis does not involve frameshifting (481, 482) , this does not detract from significance of their stimulation of a subset of frameshifting, e.g. E. coli dnaX −1 frameshifting is not stimulated by polyamines (481) . Ty1 +1 frameshifting can also be stimulated but it requires both elevated putrescine and greatly diminished spermidine (309) . Considerations derived from these analyses are relevant to the point mentioned above about potential involvement of polyamines in type III secretion system frameshifting involving YopN-TyeA hybrid synthesis (331).