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.

While transcriptional and translational frameshifting are distinct, there may well be sites at which both occur. With both there is a shift-prone site ('slippery'/'shifty' site) at which the non-standard event occurs. In some instances, e.g. in decoding certain tailed phages, influenza A virus and likely closteroviruses (36-41), and maybe antizyme 3 (see below), the ribosomal shift seems not to involve stimulatory signals and despite its low efficiency leads to the synthesis of important proteins. An example with polymerase realignment for low efficiency but high importance frameshifting occurs with potyviruses (42) (43) (44) . For both transcriptional and translational frameshifting, the efficiency of the nonstandard event is often greatly enhanced by stimulatory (recoding) signals, though current knowledge of such signals for transcriptional realignment is very limited. Nevertheless, very elaborate recoding signals are present sometimes, even when only low efficiency frameshifting occurs, for instance in several mobile elements (45) , but also for adenomatous polyposis coli (APC) (46) .