50,000 'knots' scattered throughout our DNA control gene activity

Scientists have mapped tens of thousands of Mysterious "knots" in human DNA, and they may play a key role in controlling gene activity.

Knowing the exact locations of these knots — known as "i-motifs" — could lead to the development of new treatments for diseases, including cancer, according to the researchers behind the work.

DNA is composed of building blocks called nucleotides, each of which carries one of the following bases: adenine, guanine, thymine or cytosine. These bases are the individual letters that make up DNA's code. DNA has a ladder-like structure, and normally, bases on one side of the ladder pair with a partner on the other side, linking up in the middle to form the ladder's rungs. Adenine pairs with thymine, while guanine pairs with cytosine.

However, sometimes, cytosines can pair with each other, rather than with guanine. This causes a DNA molecule to twist in on itself, creating a four-stranded, protruding structure called an i-motif.

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Researchers first discovered i-motifs in human cells in 2018. At the time, they suspected these knots could be important regulators of the genome, helping to control which genes are on or off. However, until now, little has been known about exactly where these knot-like structures are found and how many of them there are in the human genome.

In a new study, published Aug. 29 in The EMBO Journal, researchers mapped 50,000 i-motifs. These i-motifs are located throughout the genome, but they are commonly found in stretches of DNA that control gene activity, the study authors noted.