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.

Vectors whose products permit estimation of the proportion of ribosomes that shift from translating the zero to the alternative frame of interest have provided many insights to frameshifting. While they avoid some comparative problems with solo reporters, they have different 'issues'. Commonly the 5 end of the frameshift cassette being tested is fused in the zero frame to the 3 end of the reporter used to reflect zero frame decoding, and its 3 end is fused to a downstream reporter such that its decoding monitors new frame reading. When the 5 encoded reporter is assayed by enzyme activity, care is needed to avoid or be cognizant of, distortions due to features of its C-terminal extension though for the 3 encoded reporter its being on the C-terminal side of a trans-frame encoded fusion product can also be relevant. Vector systems where both products can be assayed in the same tube, such as firefly and renilla luciferase (659) have proved popular, though fluorescence reporters, e.g. (660, 661) , have been gaining ground. Plasmid-based expression has been very valuable, but in certain cases can yield over-expression artifacts avoidable with chromosomal integrants (427) .