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.

ing required for antizyme synthesis, the frameshifting is a very significant component of the regulatory repertoire (264) (265) (266) (267) (268) . There are three antizymes in mammals (see below), more in the fish, D. rerio (269) (270) (271) , and one in each species from Drosophila to C. elegans to S. cerevisiae yeast (272) (273) (274) . Frameshifting does not occur in the decoding of the antizyme gene from the ciliate Tetrahymena (270) where UGA is reassigned from being a stop codon. An antizyme gene is not present in extant plants. Binding of mammalian antizyme 1, but not antizymes 2 or 3, to an ornithine decarboxylase monomer causes a conformational change that, without the involvement of ubiquitination, targets the ornithine decarboxylase monomer for degradation by the 26S proteasome via its own C-terminal segment (275, 276) , and at least in S. cerevisiae the counterpart targeting is promoted by polyamine binding to antizyme (277) . Polyamine binding to antizyme also influences ubiquitin-dependent degradation of antizyme itself (277) , and antizyme has similarities to a key polyamine catabolic enzyme, spermidine/spermine N-acetyltransferase, that directly binds polyamines.