The preQ1 riboswitch is a target for antibiotics and other small molecule therapies. The preQ1riboswitch and portions thereof can be used to regulate the expression or function of RNA molecules and other elements and molecules. The preQ1 riboswitch and portions thereof can be used in a variety of other methods to, for example, identify or detect compounds. Compounds can be used to stimulate, active, inhibit and/or inactivate the preQ1 riboswitch. The preQ1 riboswitch and portions thereof, both alone and in combination with other nucleic acids, can be used in a variety of constructs and RNA molecules and can be encoded by nucleic acids.