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A new approach to CRISPR technology, focusing on RNA rather than DNA, is poised to revolutionize how we detect and combat viral infections. Researchers at Utah State University are making significant strides in understanding lesser-known CRISPR systems, potentially paving the way for more precise and effective diagnostic tools and therapies.
The body’s natural immune defenses constantly work to prevent viruses from replicating. The well-established CRISPR systems achieve this by targeting and cutting the DNA of invading pathogens, disabling their ability to infect cells.However, a team led by chemist Ryan Jackson is exploring the potential of Cas12a2 and Cas12a3, CRISPR systems that operate differently. Unlike the widely used CRISPR-Cas9, which homes in on DNA sequences using a guide RNA, Cas12a2 and Cas12a3 directly target
RSV infections – individually or in combination – from a single patient sample.
Distinct Mechanisms: Cas12a2 vs. Cas12a3
Jackson and his team are meticulously mapping the distinctive features of both Cas12a2 and Cas12a3. The key difference lies in their method of action. “Rather of making a single break in the bound target,as Cas9 does with DNA,binding of the RNA target by Cas12a2 and Cas12a3 changes the shape of a protein in a way that activates it to cut another nucleic acid target again and again,” Jackson says.
This activation leads to different outcomes for each system. Cas12a2, when activated, indiscriminately cleaves DNA, effectively destroying viral DNA but also harming the host cell. Cas12a3, however, exhibits a far more targeted approach. It cleaves transfer ribonucleic acids (tRNAs), interrupting the production of viral proteins while leaving the host cell’s DNA intact.
This precision is what makes Cas12a3 notably promising. “This latter capacity allows Cas12a3 to target tRNA very precisely,” Jackson notes. “we are trying to harness this ability to detect and target specific pathogens.”
tRNA: The Keystone of Protein synthesis
Understanding the role of tRNA is crucial to appreciating the potential of Cas12a3. As Jackson explains, “tRNA is the keystone of protein synthesis. It functions as a translation device that can read the RNA code and act as a molecular bridge to connect that code to the correct amino acid to enable protein production.”
Cas12a3’s ability to disable this translation process is a game-changer. By cutting a specific region of the tRNA, known as the “tail” which contains the amino acid, Cas12a3 effectively halts protein production. “this is a very powerful and precise way to stop a pathogen, including a virus, from replicating in a cell, without damaging the cell’s DNA,” Jackson emphasizes.
This mechanism represents a recently discovered CRISPR immune response, and researchers believe it might very well be a significant therapeutic breakthrough. “We think being able to stop an invading pathogen while leaving the DNA unchanged could be a therapeutic breakthrough,” Jackson states. “By studying these systems, we are also discovering the enormous functional diversity of these bacterial defense mechanisms.”
Crosby and Filani were instrumental in defining the functions of Cas12a3 and its potential as a diagnostic tool. The research benefited from collaboration with Chase Beisel of the Helmholtz Institute for RNA Infection Research in Würzburg, Dirk Heinz of the Helmholtz Center for Infection Research in Braunschweig, and researchers from institutions across Poland, France, Germany, Austria, and Austria. Funding for the project was provided by the R. Gaurth Hansen family and the National Institutes of Health.
The ongoing research into Cas12a2 and Cas12a3 represents a significant leap forward in our understanding of CRISPR technology and its potential to combat viral infections with unprecedented precision and efficacy.
