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.

Some cases of ribosomal frameshifting are more detectable in specific cell types, e.g. where the amount of a particular aminoacyl-tRNA is low, at certain stages of growth, e.g. bacterial stationary phase, or in a particular phase of a viral infective cycle. Other novel cases are claimed in yeast under oxidative stress (9) , in the context of broader translational adaptations (10) . An extreme in this regard is the retention over long evolutionary time of the ability of S. cerevisiae release factor, eRF3 to convert to its [PSI+] prion form and ribosomal frameshifting associated with it (11) (12) (13) that may have survival value under stressful conditions and create the opportunity for a later mutational change to genetically fix the newly advantageous trait (14) (15) (16) . Intriguingly, [PSI+] induces synthesis of a substantial amount of a trans-frame encoded variant from the gene for eIF1, and specific other translation initiation, tRNA maturation and amino acid metabolism genes (13) . In other cases, even when high level, frameshifting can be effectively inconsequential. In some, the signals promoting the high level were selected for a different purpose, and efficiency of degradation of 'dangling tail' C-terminal extensions is also relevant (17) (18) (19) .