Discovery of CRISPR's long lost ancestor may expand gene-editing toolkit
CRISPR may be a powerful technology for gene editing, but the system existed in bacteria long before scientists began using it. For billions of years, CRISPR has acted as a natural immune system in bacteria and other microbes, helping defend them against invading viruses. But now, two new studies, published in Science, describe a similar RNA-guided system that originated in the viruses themselves…
Two new studies published in Science have uncovered evidence of a long-lost ancestor of CRISPR, a powerful gene-editing technology. CRISPR, which uses RNA guides to find matching DNA sequences and can be programmed to make precise changes to DNA, was initially thought to have evolved in bacteria as a natural immune system to defend against invading viruses.
However, researchers have now discovered a similar RNA-guided system in viruses, which may have originated as an ancient "arms race" between viruses competing for control inside bacteria. This proposed evolutionary link between the viral system and CRISPR is supported by the identification of an RNA-binding protein called VIPR, which uses a unique "skip-one" code and protein-driven DNA triplex formation to recognize and target DNA.
VIPR was found in both bacterial and viral genomes along with a small noncoding RNA, and was able to silence selected genes and protect bacteria from phage infection in experiments. The researchers suggest that VIPR systems have the potential to be used for genome editing, DNA locus imaging, and epigenetic modification due to their minimal and potentially versatile design.
However, more work is needed to fully understand the evolutionary link between VIPR and CRISPR and how VIPR guide-RNA libraries evolve and gain new targets.
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