Each cell must regulate the expression of hundreds of different genes in response to changing environmental or cellular conditions. The majority of these sophisticated genetic control factors are proteins, which monitor metabolites and other chemical cues by selectively binding to targets. We have confirmed that RNA also can form precision genetic switches and that these elements can control fundamental biochmemical processes.

Riboswitches are a type of natural genetic control element that use untranslated sequence in an mRNA to form a binding pocket for a metabolite that regulates expression of that gene. Seven riboswitches are under investigation and it appears as though this mechanism of genetic regulation is widespread in bacteria. These natural RNA switches are the latest illustration of how functional RNAs are engaged in fundamental cellular processes.

Riboswitches are dual function molecules that undergo conformational changes and that communicate metabolite binding typically as either increased transcription termination or reduced translation efficiency via an expression platform. Some riboswitches have been detected in eukaryotes, supporting the view that riboswitches might be an ancient form of genetic control that has persisted since the "RNA World." The evolutionary consequences of this finding are being explored.