In this article from the American Chemical Society, Maarten Merkx and his colleagues research how to use and combine CRISPR-related proteins with a bioluminescence technique whose signal could be detected with a digital camera. This new technique can diagnose illnesses faster while being much more efficient and practical. Bioluminescence is a chemical reaction involving the luciferase protein that causes the luminescent, glow-in-the-dark effect. The luciferase protein has been incorporated into sensors that emit an easily observed light when they find their target, but they lack the incredibly high sensitivity required of a clinical diagnostic test.
CRISPR, a gene-editing technique, has the ability to increase sensitivity, but it requires many steps and additional specialized equipment. With the new technique, called LUNAS (luminescent nucleic acid sensor), two CRISPR/Cas9 proteins specific for different neighboring parts of a viral genome each have a distinct fragment of luciferase attached to them. If a specific viral genome that the researchers were testing for was present, the two CRISPR/Cas9 proteins would bind to the targeted nucleic acid sequences and come close to each other, allowing the complete luciferase protein to form and shine blue light in the presence of a chemical substrate. RPA-LUNAS successfully detected SARS-CoV-2 RNA within 20 minutes, even at concentrations as low as 200 copies per microliter.
This is similar to the process of gene regulation that uses an inducible operon as we learned in class. An inducible operon is a type of negative regulation that turns on when it interacts with an inducer. It is usually off which means there is an active repressor that binds to the operator to block the RNA polymerase from transcribing the DNA. When there is the inducer, such as the virus, the inducer inactivates the repressor by binding to the allosteric site which allows the RNA polymerase, such as the CRISPR/Cas9 proteins, to transcribe and eventually produce the protein, such as the luciferase protein.
As we are recovering from the devastating COVID-19 Pandemic, how can new medical advancements and technology help us prepare for future outbreaks?
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