Two molecular bioscience researchers at UT helped discover a new type of CRISPR protein. 

CRISPR is a protein that has the ability to destroy viruses by detecting and killing the DNA within the bacteria, co-author Jack Bravo said. CRISPR proteins that are injected with virus genetic material and remember the virus, after which they can then use this “immune memory” to target the same viruses if they reinfect the bacteria. Bravo and his team’s newest CRISPR discovery called Cas12a2, can destroy the RNA instead, eliminating the virus’s ability to replicate, Bravo said.

“(Detecting the RNA) induces basically bacterial cell suicide,” said Bravo, a molecular biosciences postdoctoral fellow. “That means the viruses then can’t spread and destroy the entire population.” 

David Taylor, an associate professor of molecular biosciences whose lab conducted the research, focuses on structural biology. Taylor said the lab wants to clearly understand the functions of proteins like CRISPR.

“Cas12a2 is interesting because it’s like a self-destruct button,” Taylor said. “Once it finds its target, instead of just clearing its targets, what it does is that it binds to its target RNA … it then will basically cleave all nucleic acid that’s all around it. And so what that ends up causing is that bacteria to die. It’s like if I threw myself in front of a bus for you … I’m (going to) kill myself because it’s going to help the whole population of bacteria around me right so that they don’t get infected. I don’t keep infecting people.” 

Because the protein requires specific conditions to become activated it took the team four years to make progress, Bravo said. 

“It was quite hard to find the right conditions to perform our experiments in,” Bravo said. “The techniques that we use to image the proteins or the complexes that we work on (are) called cryo-EM. You have your complex or your protein solution and then you apply a thin layer to a tiny grid, and then you plunge it into liquid nitrogen. And this means that the solution freezes rapidly and you get this glossy, low-contrast ice.”

The new protein would use guide RNA that is injected into the CRISPR protein to detect RNA of the same genetic material in bacteria, allowing for the detection of different viruses, Taylor said.  

“All you have to change to detect something different is that guide RNA,” Taylor said. “Should I make an RNA sequence complementary to the “Walking Dead” zombie virus? Should I make it complementary to COVID? We think it might be able to be used as a versatile diagnostic.”