Scientists Discover New Form of DNA Structure in Human Cells

A team of researchers has just discovered a new form of DNA structure, that looks like a “twisted knot.” The newly found structure, dubbed the “intercalated motif” aka the “i-motif,” plays a central role in the way the DNA code is read.

The DNA component was first discovered two decades ago, but it is the first time a group of scientists spotted it in living human cells.

A study detailing the findings appeared in the Nature Chemistry journal this week.

 When most of us think of DNA, we think of the double helix,

co-author Daniel Christ said.

He added that the latest research brings proof that there are different types of DNA, not just the double helix one.

The double helix structure was first discovered in 1953 by Francis Crick and James Watson. The structure is shaped like a twisted ladder. The twisted knot is very different from the double helix.

The New Form of DNA Structure Turns Genes On and Off

The i-motif is made of four strands tied in a “knot”. In this structure, the nucleotides called cytosine (C) in a strand create a pair with each another. In the double helix structure, the cytosines bind to the guanines (Gs) in the opposite strand.

Researchers were able to detect the twisted knot shapes in living cells through tiny bits of antibodies that are attracted to the i-motif shapes. The team engineered the antibodies to bind to those structures alone.

• Next, the team poured fluorescent dye on the antibodies to track their location in various types of the human cells.
• Scientists could see the location of the i-motifs by looking at the green spots.

The green spots vanished over time which means that the i-motifs form, dissolve, and form again. The newly discovered DNA shapes seem to switch genes on and off and decide whether a gene is read or not.
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