Release date: 2017-09-04
The well-known journal Cell magazine recently published the latest results of the Jennifer Donner team, the co-discoverer of the CRISPR-Cas9 gene editing tool: they found that the two proteins inhibiting Cas9 activity, ACRIIC1 and ACRIIC3, are completely different by X-ray diffraction. The mechanism of action, and ACRIIC1 has broad-spectrum inhibition, which can play the role of "brake device" in different gene editing systems, allowing the gene editing process to terminate at an appropriate time, reducing the off-target effect.
Although the CRISPR-Cas9 system is simple and efficient, there is a major safety hazard: the system cannot stop the cutting function after the wrong gene is repaired, but may continue to modify the normal gene, resulting in off-target effects. Scientists have been hoping to find a "safety gate" from the bacterial natural system that shuts down the gene editing process in time.
At least seven Cas9 inhibitory proteins (ACR proteins) have been previously discovered, with the ability to stop cells from cutting and editing. This time, the Donner team selected two proteins that were shown to inhibit Cas9 in human cells and found that they have completely different ways of action. ACRIIC1 binds tightly to the two important amino acids that bind DNA in Cas9, allowing Cas9 to lose its ability to cleave DNA. ACRIIC3 alters its structure by allowing two Cas9 molecules to form a dimer, allowing Cas9 to no longer bind to DNA. Based on two different mechanisms, ACRIIC1 inhibits a wide variety of different Cas9 proteins with broad-spectrum properties, while ACRIIC3 only inhibits a protein called NmeCas9.
Huang Zhiwei, a professor at the School of Life Science and Technology of Harbin Institute of Technology, published a heavy paper in Nature in April this year. He first studied the mechanism of action of another Cas9 inhibitor, ACRIIC4, and confirmed that it can effectively inhibit SpyCas9. Gene editing activity. In an interview with the Science and Technology Daily, Professor Huang said that their research results were earlier than those reported by the Donner team. There is no evidence that ACRIIC1 and ACRIIC3 have better inhibitory effects than ACRIIC4, but they can be found most effectively through comparative studies. The inhibitory protein, added to the gene editing system, allows Cas9 to "close" function on time after completing the gene editing task, avoiding off-target effects.
Source: Technology Daily
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