MicroReview New insights into riboswitch regulation mechanisms

Summary Riboswitches are genetic elements located in non- coding regions of some messenger RNAs (mRNAs) that are present in all three domains of life. The binding of ligands to riboswitches induces conforma- tional changes in the mRNA molecule, resulting in modulation of gene transcription, or RNA splicing, translation or stability. This mechanism of regulation is particularly widespread in bacteria and allows a direct response to various metabolic changes. A large number of riboswitches have been discovered in the last few years, suggesting the existence of a huge diversity of regulatory ligands and genetic mecha- nisms of regulation. This review focuses on recent discoveries in riboswitch regulatory mechanisms as well as current outstanding challenges.