In living cells DNA was first found in the form of a node

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<pre>In living cells DNA was first found in the form of a node

Few people know that in addition to the classical double helix discovered in 1953, DNA may have other forms. The discoverers of DNA, Watson and Creek, did not report this because they were not sure that these were real molecules, and not just “garbage”, snippets of larger chains. However, recently at the Institute for Medical Research in Garvan have created a tool that has made it possible to get to the truth. For example, it is definitely established that there is DNA in the form of a node. But what is its role?

The coding of information about the structure of a living organism in DNA is realized not only by a unique sequence of nucleotides, but also by the form of the molecule itself. The form of the chain determines how it contacts the RNA, how the information written in it will be “read”. And from this point of view, the structure of i-motif, a knot of four nucleotide chains, raises many questions. Here the nucleotides C on one chain are connected with each other, whereas in the helix they always interact with the nucleotide G – and then only on the opposite chain.

If the DNA helix exists stably, i-motif has the property of disappearing and reappearing. Australian scientists have created a fragment of an antibody molecule that can only interact with i-motif and upon contact triggers a fluorescence reaction. Further, studying the order of appearance of green spots on the investigated medium, they began to study the patterns. It is believed that i-motif is activated at key moments in the life of DNA and can “turn” and “turn off” individual genes.

It has already been proved that nodal DNA lives in telomeres, protective “caps” at the ends of chromosomes, which play a major role in the biological aging of the organism. And they show activity during the last phase of the cell's life cycle, during the reading of DNA to create a new cell. But what exactly does i-motif do, scientists can not answer yet – they are aware of themselves at the threshold of discovery, but the research is far from complete.

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