My postdoctoral research focuses on targeted control of bacterial gene expression using artificial repressors. Techniques that enable biologists to control the expression of genes of interest are essential for investigating bacterial pathogenicity, probing complex cell physiology, and producing medically relevant natural products. Many molecular tools available for altering prokaryotic gene expression at the transcriptional (e.g. promoter replacement, artificial zinc fingers), post-transcriptional (e.g. non-coding antisense RNAs), and translational (e.g. initiation signals, codon optimization) levels either work in cis or are limited by cost, implementation, or unintended side effects to cell function. In order to study increasingly complex regulatory systems and construct more intricate metabolic pathways, simple trans acting molecular tools are needed.
Transcription activator-like effectors (TALEs), originally discovered as plant virulence factors from Xanthomonas bacterial species, have recently shown promise as tools to specifically manipulate the expression of genes in a wide range of organisms. Surprisingly, the functionality of engineered TALEs as regulators of bacterial gene expression had not been explored until only recently by our lab. I will examine the versatility of engineered TALEs to serve as artificial transcriptional repressors in bacteria.
I am using the well-studied operator-repressor system of the E. coli lac operon as a platform to examine the fundamentals involved in TALE-mediated repression of bacterial transcription. I will examine the ability of a TALE targeted to the lac operator sequence to inhibit bacterial transcription initiation and elongation in vivo and quantitatively determine how critical features of TALE primary structure (e.g. number of repeats and RVD composition) contribute to TALE-DNA binding. In addition, I will develop an inducible TALE repressor system based on small-molecule mediated dimerization of proteins.