Artificial riboswitches and other ligand-responsive gene regulators make it possible to switch protein synthesis ON or OFF with arbitrary ligand molecules. Artificial Riboswitches: Methods and Protocols focuses on the state-of-the-art methods developed in recent years for creating artificial riboswitches, therefore this volume could be regarded as a collection of recipes for the gene circuit elements in synthetic biology and metabolic engineering. Chapters cover topics such as screening or rational design methods for obtaining artificial riboswitches that function in either bacterial or eukaryotic translational systems, protocols for evaluating the activities of the resultant riboswitches, as well as protocols for construction of ligand-dependent, trans-acting gene regulators. Written in the successful Methods in Molecular Biology series format, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible protocols, and notes on troubleshooting and avoiding known pitfalls. Authoritative and easily accessible, Artificial Riboswitches: Methods and Protocols seeks to serve not only bioengineers who aim to reprogram cell behaviors and molecular biologists who leverage these regulators for genetic studies, but to all researchers interested in this fascinating field.