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.

Ty1 frameshifting decreases 4-fold in glycerol-lactate grown cells compared to cells grown in media with the preferred carbon and energy source, glucose (625), and glucose level effects with bacterial IS1 have also been reported (623) . Ty3 frameshifting efficiency varies up to 10-fold depending on the carbon source, but in contrast to Ty2, it is lower in glucose grown cells than in poorer carbon-source media (625) . Previously it was shown that Ty3 Pol and transposition decreases dramatically with high temperature or growth in ethanol (626) where the frameshifting rate is greatly reduced (216) . (Possible cold shock effects have in general not been studied to date.) Genetic studies strongly indicate that under growth in the poorer carbon sources, one or two kinases phosphorylate the ribosome-associated protein Stm1p which in turn affects the Ty3 frameshifting level (216) . Stm1p is involved in the regulation of eEF3, a yeast-specific elongation factor that facilitates binding of aminoacyl-tRNA to the ribosomal A-site. How many other cases of retrotransposon frameshifting are responsive to alterations of the translation elongation process is a significant unresolved issue. Perhaps mechanistically quite distinct, but an indication of the potential diversity is that there is elevated D. melanogaster 1731 retrotransposon gag-pol frameshifting in males compared to females (627) .