Our Sensor

The goal of our project is to design a biosensor to rapidly identify cattle known as super shedders. Super shedders are cattle that excrete extremely large numbers of E.coliO157:H7, a subgroup of E. coli referred to as Enterohemorrhagic E. coli (EHEC). EHEC organisms produce a toxin called Shiga toxin or verotoxin, which causes hemolytic-uremic syndrome (HUS) in humans and can be deadly.

We are building a DNA-based biosensor that specifically detects the gene called stx2 that is common among all EHEC organisms. Our device will be useful for the detection of not only the O157:H7 strain of E.coli but for the other EHEC strains as well. Click on the components above to learn more about their design and function. View our animation below to see how the system would actually work!

The FerriTALE System:

As seen in the video above our goal is to have a strip system that will be able to detect target DNA. This is accomplished by binding a TALE-Ferritin scaffold (a FerriTALE!) to a nitrocellulose strip. Once this strip is blocked, sample DNA will be run through the strip and captured by via a specific target sequence using our DNA binding TALEs. A second TALE attached to our reporter (Prussian blue ferritin or beta-lactamase) that targets another specific sequence on the captured DNA is run through this strip. After this step we add a substrate solution and if both TALEs have successfully bound the target DNA we will see a colour output on the strip.

One of the powerful potentials of our system is that it is a platform technology. We are using TALE proteins as our sensory element. TALEs are very powerful tools since they can be engineered to bind to any 12 to 31bp sequence of DNA (source: Golden Gate TALEN and TAL Effector Kit 2.0). Therefore, by just changing the TALEs in our parts, one can use the part to detect any DNA of interest. To further ease this process, we have incorporated a KasI restriction cut site at the end of all TALEs in all the constructs. Using the KasI restriction enzyme and one of the biobrick prefix enzymes one can incorporate their own engineered TALE into the part, and use it for detecting their DNA of interest.