Genetic Circuits in Salmonella typhimurium

Abstract

Synthetic biology has rapidly progressed over the past decade and is now positioned to impact important problems in health and energy. In the clinical arena, the field has thus far focused primarily on the use of bacteria and bacteriophages to overexpress therapeutic gene products. The next generation of multigene circuits will control the triggering, amplitude, and duration of therapeutic activity in vivo. This will require a host organism that is easy to genetically modify, leverages existing successful circuit designs, and has the potential for use in humans. Here, we show that gene circuits that were originally constructed and tested in Escherichia coli translate to Salmonella typhimurium, a therapeutically relevant microbe with attenuated strains that have exhibited safety in several human clinical trials. These strains are essentially nonvirulent, easy to genetically program, and specifically grow in tumor environments. Developing gene circuits on this platform could enhance our ability to bring sophisticated genetic programming to cancer therapy, setting the stage for a new generation of synthetic biology in clinically relevant microbes.

Measuring Growth and Gene Expression Dynamics of Tumor-Targeted <em>S. Typhimurium</em> Bacteria

“…S. typhimurium is an excellent strain for clinical synthetic biology for cancer therapy since it is similar to E. coli, specifically colonizes tumors, and has been shown safe in human clinical trials 6,12,14,22 . Additionally, recent studies have found that many published circuits function in S. typhimurium without modification 24 . Using the experimental platform described here, we recently described how dynamic in vivo expression profiles can be programmed using the inherent instability of plasmid vectors 25 .…”

Synthetic biology platform technologies for antimicrobial applications

“…For example, the natural macrophage-homing mechanism of Salmonella has been used to introduce antigenic peptides to immune cells for prophylactic purposes, and for the delivery of ribozymes designed to inhibit macrophage-specific viral infections, such as cytomegalovirus [94][95][96][97]. The employment of attenuated Salmonella in vaccine delivery has promising commercialization potential and is currently the basis of several clinical trials [98,99].…”

Making gene circuits sing

“…This disparity is an illustration of host context dependence (18): a circuit may work in one host and work differently or not at all in another, often without clear reason. This issue is extremely important as we move beyond E. coli toward the programming of other microbes (19). A promising solution described by Egbert et al is to explicitly build tuning knobs into the circuits and adjust them to compensate for host-specific differences.…”