Translated material
Two rings, two ends, in the middle of the nobe
Why did the Swedish Academy recognize “DNA scissors” so quickly? Explains the biologist Alexander Panchin
Expert card
Alexander Panchin - Russian molecular biologist, candidate of sciences, senior researcher at the Harkevich Information Institute of Information Problems, science popularizer.
Mutagenic chain reactions, editing DNA of human embryos, creating plants resistant to viruses, cutting out of human cells - this is only a small part of what the “molecular scissors” CRISPR/CAS9 managed, for the opening of which the Nobel Prize in chemistry of 2020 was presented.
For people interested in biology, this is probably one of the most anticipated, and therefore predictable Nobel Prizes of the decade.
The question was not whether someone would reward for CRISPR/CAS9, but to whom and when.
Many scientists have to wait for Honored Nobel for decades, but Jennifer Dudna and Emmanuel Charpentier received her for the discovery, which was made only eight years ago - the technology turned out to be so broken. Let's figure out what it is.
It all started with the fact that bacteria found an antiviral protection system, which in some way resembles a computer antivirus. This system consisted of two parts: CRISPR (the replenished “database” of viral genetic fragments) and CAS9 (protein using information from this “database” to recognize viral DNA and cut it). Dudna, Charpentier and their colleagues showed that these “molecular scissors” can be reprogrammed and directed to a variety of DNA sequences, not necessarily viral. That is, they can be turned into a tool for genetic engineering.
The charm of this tool can be described using a metaphor. The set of DNA molecules or the genome of the body is in a sense text, a giant book written with the help of four types of letters-nucleotides a, t, g and c.
CAS9 is a contextual replacement tool that allows you to cut one phrase from the book and insert another instead.
The previously existing DNA cutting tools could only learn a small number of letters (usually from four to eight), and for each combination of letters it was necessary to look for its enzyme. CAS9 can find out about 20 letters, and you yourself choose which ones. But this is not the limit - scientists have already managed to improve this tool for genetic modification and created CAS9 -based systems that learn more than 40 letters, that is, an order of magnitude more accurate.
Of course, the technology also has disadvantages.
Nevertheless, sometimes cutting and stitching DNA can not happen as the experimenters would like.
When it comes to using CAS9 to create genetically modified plants or animals, this does not seem to be a problem. You can always redo experiments if something goes wrong. But this is a very big problem if we are talking about the scenario of editing people's genomes.
In 2018, Chinese scientist He Jiankui said that he used CAS9 in an attempt to give resistance to HIV two twins named Lulu and Nana. This statement caused a number of questions: why conduct genomic editing, while the technology can still give side changes in DNA? Especially when there is no medical need.
Loud discussions also affected mutagenic chain reactions. This is a tool made on the basis of CAS9 protein, which allows the transmission of a certain genetic change to all descendants of the body, and not just half, as with ordinary sexual reproduction. A mutagenic chain reaction allows you to engage in genetic editing of natural populations.
The mention and less interesting to the public, but very important for specialists, the CAS9 modification, which allows not to change DNA, but edit various marks that can be attached to it and influence the work of genes. This is called epigenome editing .
At the beginning of the article, I mentioned that the question was not whether they would give a bonus for CRISPR/CAS9, but to whom they would give it. The fact is that other scientists played a role in the development of this technology. For example, in the Zhang Feng laboratory, for the first time, it was shown in practice that with the help of CAS9 protein it is possible to edit not only DNA of bacteria and viruses, but also the genomes of eukaryotes - organisms whose cells contain nuclei. This has become a starting point for numerous technology applications on animals and plants. One of the hypotheses about why CRISPR/CAS9 did not give a bonus earlier is that the Nobel Committee did not want to interfere with the disputes of scientific groups for various patents around the technology.
A group of scientists, including biologists Evgeny Kunin, Kira Makarov and John Van Der Oost, established the role of CAS9 protein in antiviral protection of bacteria. Their 2008 work is quoted more than two thousand times and, of course, played a crucial role in the emergence of the technology under discussion. And even more people participated in the improvement of CAS9 and the development of technology based on this protein. I would not be surprised if the Nobel Prize in physiology and medicine this year was also connected with CRISPR/CAS9, although this did not happen.