Updated CRISPR
Biologists explained how the "error-free CRISPR" works
Sergey Kolenov, Hi-tech+
A new gene editing tool was introduced in the summer. Now scientists have managed to examine its work at the level of individual molecules. The study confirmed that this technology is much superior to traditional CRISPR in both editing accuracy and security.
A few years ago, the CRISPR gene editing technology made a real splash among biologists. However, the euphoria gradually subsided, and the researchers drew attention to the numerous shortcomings of the "genetic scissors", including the inaccuracy of corrections and the high risk of non-targeted mutations.
Since then, many teams have been trying to improve CRISPR or find a replacement for it. In the summer of this year, experts from Columbia University: INTEGRATE gene Editing tool.
Like CRISPR, the new technology is borrowed from bacteria. It is based on the "jumping gene" of the cholera pathogen Vibrio cholerae. Such genes, which are known to biologists as transposons, are characterized by the ability to independently cut themselves out of the genome and insert them into a new place without cutting the DNA strand.
INTEGRATE works on a similar principle. The tool allows you to insert large fragments of DNA into the genome without violating its integrity.
This eliminates the mistakes that the cell can make when restoring the incisions. In addition, INTEGRATE can be used in cells that do not cope well with DNA repair – for example, in neurons.
In the course of a new study, which is described by the press release of Columbia University Irving Medical Center First Images of an “Upgraded” CRISPR Tool, scientists using cryo-electron microscopy analyzed the work of INTEGRATE at the level of individual molecules. It turned out that the protein complex consists of two main sections. The large one, called Cascade, carries a guide RNA and searches for the corresponding section of the genome. Having found a match, it passes a DNA strand through the proteins of the TniQ complex and recruits other enzymes to insert the desired sequence.
As the researchers found, TniQ does not work separately from Cascade. This ensures that the genetic fragment will be inserted only into the part of the genome that coincides with the guide RNA.
In general, the characteristics of INTEGRATE make it a very promising candidate for the role of CRISPR's successor. The authors plan to continue studying it and eventually present methods of gene therapy based on the use of a new tool.
Article by Halpin-Healy et al. The structural basis of DNA targeting by a transposon-encoded CRISPR-Cas system is published in the journal Nature – VM.
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