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.

The sugarcane yellow leaf virus frameshift stimulatory pseudoknot, which is similar to its beet western yellows virus counterpart, also has compact features that involve extensive non-Watson-Crick pairing and a base quadruple. It has an extended triplex between the minor groove of stem 1 and loop 3 involving interactions that have features in common with A-minor interactions (523, 561) . In this class of pseudoknots, the lowest energy 'ground state' does not correlate with frameshifting efficiency, but rather an enhancing of certain reduced stability (463, 560) . It exhibits pH-dependent, frameshift activity (523) , that by analogy to the structural switch revealed by an NMR study of the pseudoknot stimulator of Moloney murine leukemia virus gag readthrough, is very likely due to a protonation dependent switch that induces the active frameshift stimulator (562) .