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Oh, Turn It Off

Small proteins might be able to turn the gene-editing CRISPR/Cas9 tool off, a team of researchers has reported in Cell this week.

As GenomeWeb has reported, researchers from the University of California, San Francisco, have uncovered anti-CRISPR proteins. While these aren't the first anti-CRISPR proteins to be found, it says that these are the first that appear to work against the CRISPR/Cas9 system.

UCSF's Joseph Bondy-Denomy and his colleagues scoured 300 strains of Listeria for evidence of phage DNA in the bacterial genome that should've been removed by the host CRISPR system. The presence of phage DNA could indicate the presence of an anti-CRISPR system, the researchers say. "We looked for strains of bacteria where the CRISPR/Cas9 system ought to be targeting its own genome," Bondy-Denomy says, according to GenomeWeb. "The fact that the cells do not self-destruct was a clue that the whole CRISPR system was inactivated."

He and his colleagues uncovered four potential anti-CRISPR proteins in this way and named them AcrIIA proteins and numbered one through four. Of these, two worked in human cells in vitro to deactivate CRISPR/Cas9, Live Science notes.

This sort of "off-switch" could make genetic engineering safer, Bondy-Denomy adds. "These inhibitors provide a mechanism to block nefarious or out-of-control CRISPR applications, making it safer to explore all the ways this technology can be used to help people," he says.