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.

Since the bypassing of 50 non-coding nucleotides in phage T4 gene 60 is, as considered in the nascent peptide section above, so efficient, it has long been presumed that counterparts would exist elsewhere -perhaps involving shorter distances but with retention of the feature that the landing site 5 adjacent to the resume site, would match the takeoff codon. Work with synthetic constructs revealed 'stophops' where matched codons flank a stop and 9 nts specify one amino acid (54) , pointed to the significance of slow-todecode A-site codons. Over-expression, for biotechnological purposes, of a mammalian gene in E. coli soon thereafter showed that heterologous expression mediated specific aminoacyl-tRNA limitation led to counterpart hopping over a sense codon (597) . Another group studied indepth the requirements for counterpart bypassing both in starvation conditions and in normal growing cells (598) (599) (600) (601) . Lack of follow-up on reports of a 29 nt translational hop in decoding of an adhesion gene of the oral bacterium Prevotella loescheii, that is of dental interest (602), was partly due to difficulty in getting it to function in E. coli. The possibility of hopping in the expression of Leishmania RNA virus LRV2-1 was considered (603) but not investigated. Much work was required to show that two separate reports of bypassing utilization were spurious (604, 605) .