Aptamers recognize When riboswitch is on

In work with implications for functional studies and drug discovery, researchers have identified aptamer ligands (short folded RNAs) capable of distinguishing between on and off states of messenger RNA riboswitch control sequences (Angew. Chem. Int. Ed., DOI: 10.1002/anie.200603166). In its on state, a riboswitch permits mRNA to be recognized by the ribosome and translated into protein. It turns off when a ligand binds to it. The binding interaction causes a structural change that blocks protein translation, but the mechanism isn't well understood. Michael Famulok and coworkers at the University of Bonn, in Germany, screened a library of aptamers and found two of them that bind strongly and specifically to a riboswitch on state. The aptamers could help lead to a better understanding of riboswitch function and mechanism. Such ligands might also "exhibit antibiotic or antifungal activity by selectively modulating riboswitches in pathogenic microorganisms, a completely unexplored potential target class for new antimicrobial drugs," the researchers note.