作者：Science Alert 2019-10-31 17:43
Scientists in the US have developed a powerful new genome editing system that could offer significantly more precision and efficiency than the current CRISPR standard.
While CRISPR-Cas9 is a revolutionary medical technology that lay the modern foundations for editing genetic code – including variants associated with disease – there have long been concerns over its potential for imprecision.
Specifically, many fear that CRISPR-Cas9 editing carries the potential to introduce errors in the form of uncontrolled insertions and deletions in genetic code, called indels.
Researchers say the new system, dubbed 'prime editing' by its inventors at the Broad Institute of MIT and Harvard University, could change the game thanks to a new protein that enables high-precision edits of genetic targets.
"A major aspiration in the molecular life sciences is the ability to precisely make any change to the genome in any location," says genome biologist David Liu from the the Broad Institute.
"We're not aware of another editing technology in mammalian cells that offers this level of versatility and precision with so few byproducts."
The basis of the new prime editing method is an enzyme called reverse transcriptase. The CRISPR system also uses an enzyme – Cas9 – to cut DNA strands, so that alternative genetic code can be inserted.
Now, thanks to reverse transcriptase, which is used in conjunction with Cas9 in prime editing, genomic editing has been upgraded again.
In prime editing, a guide RNA called pegRNA guides a modified form of the Cas9 enzyme to snip only a single strand of DNA (preventing the double-strand breaks that can induce unintended disruptions).
After this, the reverse transcriptase enzyme directly copies edited genetic information contained in the pegRNA to the targeted genomic site.