Engineered riboswitches - an alternative means to control gene expression

Beatrix S

Department of Biology, Technical University Darmstadt, Schnittspahnstr. 10, 64287 Darmstadt, Germany


   Numerous synthetic RNA-based control devices, so called engineered riboswitches, have been developed in the last years. We have engineered riboswitches by insertion of in vitro selected, small molecule binding aptamers into untranslated regions of mRNAs, exploiting the fact that upon ligand binding the RNA structure interferes either with translation initiation, pre-mRNA splicing or mRNA stability. An advantage of these regulators is that they can be designed in principle to any non-toxic, cell-permeable ligand of choice. In addition, the direct RNA-ligand interaction renders auxiliary protein factors unnecessary.

   While many RNA aptamers have been identified that bind to a plethora of small molecules, only very few are capable of acting as riboswitch. Using a screening approach we identified aptamers which confer regulation. In a combination of genetic, biochemical and structural studies we addressed the molecular basis for these differences. We demonstrated that a destabilized and open ground state accompanied by extensive structural changes upon ligand binding is necessary for regulation while inactive aptamers are already prestructured without the ligand.

   In my talk I will present various engineered riboswitches developed for all three domains of life targeting different cellular processes. I will give a mechanistic insight into these regulators and discuss several design strategies and potential applications.