Identification of a New Antizyme mRNA +1 Frameshifting Stimulatory Pseudoknot in a Subset of Diverse Invertebrates and its Apparent Absence in Intermediate Species

The expression of eukaryotic antizyme genes requires +1 translational frameshifting. The frameshift in decoding most vertebrate antizyme mRNAs is stimulated by an RNA pseudoknot 3′ of the frameshift site. Although the frameshifting event itself is conserved in a wide variety of organisms from yeast to mammals, until recently no corresponding 3′ RNA pseudoknot was known in invertebrate antizyme mRNAs. A pseudoknot, different in structure and origin from its vertebrate counterparts, is now shown to be encoded by the antizyme genes of distantly related invertebrates. Identification of the 3′ frameshifting stimulator in intermediate species or other invertebrates remains unresolved.