Designing and Constructing Artificial Small RNAs for Gene Regulation and Carbon Flux Redirection in Photosynthetic Cyanobacteria.

Photosynthetic cyanobacteria are not only model organisms for studying photosynthesis and biological cycling of carbon in biosphere but also potential "green microbial factories" to produce renewable fuels and chemicals, due to their capability to utilizing solar energy and CO2. Therefore, strategies for gene regulation and carbon flux redirection are important for both fundamental research and metabolic engineering of cyanobacteria. To address the challenges, regulatory tools based on artificial small RNAs have been developed with satisfactory effects for single or multiple gene(s) regulation in various cyanobacterial species. When combined with the promoters of varying gradient strength and the inducible switches developed in recent years, it is now feasible to realize precise gene regulation in photosynthetic cyanobacteria for producing fuels and chemicals. Here in this chapter, we provide a detailed introduction of the design principles and constructing methods of the artificial sRNA tools to achieve accurate inducible regulation of cyanobacterial gene(s).