Martin Jinek, Krzysztof Chylinski, Ines Fonfara, Michael Hauer, Jennifer A. Doudna, Emmanuelle Charpentier
"CRISPR/Cas systems provide bacteria and archaea with adaptive immunity against viruses and plasmids by using crRNAs to guide the silencing of invading nucleic acids. We show here that in a subset of these systems, the mature crRNA base-paired to trans-activating tracrRNA forms a two-RNA structure that directs the CRISPR-associated protein Cas9 to introduce double-stranded (ds) breaks in target DNA. At sites complementary to the crRNA-guide sequence, the Cas9 HNH nuclease domain cleaves the complementary strand while the Cas9 RuvC-like domain cleaves the noncomplementary strand. The dual-tracrRNA:crRNA, when engineered as a single RNA chimera, also directs sequence-specific Cas9 dsDNA cleavage. Our study reveals a family of endonucleases that use dual RNAs for site-specific DNA cleavage and highlights the potential to exploit the system for RNA-programmable genome editing."
"*Programmable RNA Complex Could Speed Genome Editing in the Lab*
For bacteria, snipping apart DNA that bears certain signature sequences is a defense mechanism. For scientists working in the lab, the same strategy can be a powerful research tool. With a newly discovered component of an adaptive bacterial immune system, scientists have identified a targeted method of slicing DNA that they say can be easily customized for a variety of applications in the lab.
Tools that snip apart DNA strands in defined locations are essential for editing genomes in the laboratory to study or alter gene function. To target the specific site in the genome they are interested in, researchers often have to design and produce a protein that will recognize and bind to that particular DNA sequence, a laborious and time-consuming process.
“This system offers a straightforward way to cleave any desired site in a genome, which could be used to introduce new genetic information by coupling it to well-known cellular DNA recombination mechanisms.”
Jennifer A. Doudna...."
Via Gerd Moe-Behrens