According to a study published in Science Daily, a recently discovered protein has been shown to operate as a form of flexible self-destruct mechanism for bacteria, capable of deleting single-stranded RNA, single-stranded DNA, and double-stranded DNA, in a first for the genetic toolkit known as CRISPR.
This discovery might open the way for low-cost, high-sensitivity at-home diagnostic tests for various infectious illnesses such as COVID-19, influenza, Ebola, and Zika.
Cryo-EM imaging has revealed that when the protein Cas12a2 attaches to a specific sequence of genetic material from a potentially damaging virus, known as a target RNA, a side piece of Cas12a2 swings out to disclose an active site, much like a sprung-open switchblade knife. The active site begins to savage DNA as it comes into touch with it.
Researchers revealed that a single mutation to the Cas12a2 protein permits the active site to digest single-stranded DNA, which is particularly valuable for designing novel diagnostics unique to any number of viruses.
This technology may create a quick at-home diagnostic test with the same high sensitivity, accuracy, and capacity to detect a current infection as PCR-based testing for recognizing viral genetic material (inexpensive to produce without requiring specialized lab equipment). It’s also highly flexible, so it might be utilized to tackle any future RNA virus.
“If some new virus comes out tomorrow, all you have to do is figure out its genome and then modify the guide RNA in your test, and you’d have a test against it,” said David Taylor, an associate professor in the department of molecular biosciences at The University of Texas in Austin.
This diagnostic would still necessitate additional work, such as collecting saliva or a nasal sample from the patient and combining it with the team’s modified Cas12a2 protein, the guide RNA that acts as a mugshot to identify a specific virus, and a fluorescent probe designed to light up when its single-stranded DNA is cut.
The Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) system is a collection of tools found in bacteria and adopted by scientists for gene editing. This is the first CRISPR protein discovered to break such a diverse spectrum of DNA types.
“Cas12a2 effectively captures the two ends of the DNA double helix and bends it exceptionally tightly,” said Jack Bravo, a postdoctoral associate at UT Austin and co-first author of the work.
“As a result, the active site may cause damage to single-stranded DNA fragments because the core helix opens and reveals it. Cas12a2 is notable for distinguishing itself from other DNA-targeting systems in this way.”
Thomson Hallmark and Ryan Jackson of Utah State University are co-corresponding authors on the paper. The other authors include Chase Beisel of the Helmholtz Centre for Infection Research and the University of Würzburg in Germany and Bronson Naegle of Utah State University.