Protein in common bacteria could be used as a CRISPR ‘kill switch’

14 Jul 2020

Image: © nobeastsofierce/

With the hope of creating a more precise way to use CRISPR to edit RNA, scientists may use a protein called AcrVIA1 to act as a ‘kill switch’.

Researchers from Cornell University, Rockefeller University and the Memorial Sloan Kettering Cancer Center have announced that a protein found in a common strain of bacteria could help make the gene-editing technique CRISPR-Cas13 safer and more accurate.

Unlike CRISPR-Cas9 – which recent experiments have shown could have dangerous, unintended consequences in DNA – CRISPR-Cas13 instead targets RNA. Now, in a recent study published to Science, the US-based researchers said the protein AcrVIA1 has been found to halt the CRISPR-Cas13 editing process.

According to the study’s co-author, Martin Wiedmann, this discovery helps expand the “scientific toolbox to effectively use CRISPR without causing side effects”.

As part of the study, Wiedmann and lead author Alex Meeske looked at 62 strains of food pathogens from 1,500 bacterial candidates. The 62 strains were sequenced and 20 candidate proteins were isolated.

CRISPR ‘kill switch’

This revealed one strain that stood out from the rest called Listeria seeligeri, commonly found in soil. It showed that the protein AcrVIA1 – derived from L seeligeri – instantly stopped the CRISPR editing process.

Meeske said: “AcrVIA1 can be very useful in controlling application of Cas13. Anything that the Cas13 edits, this anti-CRISPR protein can shut off.

“It’s a ‘kill switch’ you can use during the CRISPR editing process, and it has become an additional tool we have at our disposal.”

However, safety concerns remain about the use of CRISPR-Cas9 for gene editing of human embryos. Last month, a team of researchers from the Francis Crick Institute published findings awaiting peer review on an experiment that showed half of edited human embryos contained major unintended genetic changes.

One gene-editing expert not involved with the Crick Institute study told OneZero that this CRISPR-Cas9 discovery should act as “a restraining order for all genome editors to stay the living daylights away from embryo editing”.

Colm Gorey was a senior journalist with Silicon Republic