Trans-Regulatory Elements As Tools for Metabolic Engineering

Metabolic engineering holds the potential to enable renewable chemical and fuel production. In order to fulfill this potential, native metabolic pathways in relevant industrial host organisms must be optimized to channel flux towards desirable molecules. The complex task of optimizing native metabolism for chemical production would be facilitated by reliable trans-acting regulatory elements with customizable target specificities, enabling engineers to probe chromosomal gene expression levels without disrupting native regulation. Fortunately, several trans-acting elements are available to knock down the expression of any target gene of interest. These include Transcription Activator-Like Effectors (TALEs), the CRISPR/Cas system of Streptococcus pyogenes, and small RNAs (sRNAs). Here, we demonstrate that TALEs may be effectively used to repress gene expression in Escherichia coli. In addition, comparative studies performed to determine if any of the three aforementioned systems are especially suited for metabolic engineering applications are presented.