

Scientists Discover That the Double Helix Isn't the Only DNA Form

DNA is most commonly found in the well-known double helix shape, but new research shows it can take another form.


One of the most familiar shapes in science is DNA’s double helix structure. First discovered in 1953, this structure uncovered a wealth of information about our genes and the DNA molecules that encode them.

But new research published in the journal Nature Chemistry says DNA isn’t always in a double helix form and can sometimes take the shape of what scientists call an "i-motif." While scientists have been able to create an i-motif DNA structure in the lab for a few years now, this new research confirms that it can also occur naturally inside human cells.

So what is an i-motif? The structure can form from ordinary double-helix DNA, usually in acidic environments. To form the i-motif, the double helix untwists and then one of the strands bunches up with a bunch of cytosine molecules. In this state, the genes can’t be read, so scientists are still trying to figure out what its purpose might be.

An i-motif structure between standard double helices. The i-motif consists of a single strand of DNA clumped together with cytosine molecules, in green.
Zeraati et. al, Nature Chemistry

To study this rare DNA structure, researchers used a unique antibody that attaches only to i-motif DNA in order to find it. DNA is normally too small to be able to look at through a microscope, but by using these antibodies the researchers could detect them anyway. When the antibodies find some i-motif DNA, they attach to it and glow brightly, letting the researchers know i-motif DNA is present.

Using this method with human cells, the researchers proved that i-motif DNA does appear in our bodies. But the purpose of this configuration still remains a mystery. The researchers suspect that i-motifs play some kind of role in regulating when genes are turned on or off. According to the study, i-motifs rapidly appear and disappear in genes while they’re being read, which suggests they play some part in that process.

Once scientists answer the "why" of i-motifs, there are all kinds of things we could do with them, medicinal or otherwise. That momentous discovery of double helix 65 years is still an unfolding scientific story with no end in sight.

Source: Nature Chemistry via Gizmodo

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