ENGINEERING AND CHARACTERIZING RNA GENETIC REGULATORS Sarai Itagaki Meyer, Ph.D. Cornell University 2016 The ability to predictably and accurately control gene expression is a fundamental requirement for synthetic biologists as they seek to harness the power of cellular machinery for real-world applications. To do so requires well-behaved genetic regulators that can be assembled to create the desired pattern of gene expression—be it the conditional translation of a reporter gene for molecular sensing or the phased production of pathway enzymes for the synthesis of a biopharmaceutical. I sought to engineer and characterize genetic regulators to address this need, focusing on regulators constructed of RNA because of its functional versatility, predictable folding, and ease of characterization. The research presented here covers the construction of RNA regulators designed to respond to external signals in the form of small molecules or light exposure, as well as the characterization of a naturally occurring RNA responsive to changes in temperature. In addition, I also report on the successful engineering and optimization of a series of synthetic small RNA transcriptional activators. Together, these projects expand the toolkit of genetic regulators available to synthetic biologists and inform future RNA engineering by improving our understanding of the RNA structure-function relationship.