Fusions of a ribozyme and an aptamer of a natural riboswitch (thiamine pyrophosphate, TPP) are used to construct artificial thiamine‐dependent switches of gene expression. As J. S. Hartig et al. describe in their Communication on page 2715 ff. , insertion of these RNA elements into bacterial mRNAs allows translation of the message to be switched on or off. TPP triggers changes to the ribozyme‐mediated mRNA cleavage, resulting in liberation of the message for translational initiation.
RNA Lego : The use of natural riboswitch aptamers in synthetic RNA switches (see picture) should broaden the scope of artificial RNA regulators dramatically. It is shown that thiamine pyrophosphate (TPP) aptamers can be used in engineered devices as very sensitive switches of gene expression in unmodified organisms. The approach demonstrates that intrinsic metabolites can be utilized as external effectors of cellular functions.
