Does Disparate Occurrence of Autoregulatory Programmed Frameshifting in Decoding the Release Factor 2 Gene Reflect an Ancient Origin with Loss in Independent Lineages?

In Escherichia coli an autoregulatory mechanism of programmed ribosomal frameshifting governs the level of polypeptide chain release factor 2. From an analysis of 20 sequences of genes encoding release factor 2, we infer that this frameshift mechanism was present in a common ancestor of a large group of bacteria and has subsequently been lost in three independent lineages.