New DNA Structure Found

This is an artist's impression of the i-motif DNA structure inside cells, along with the antibody-based tool used to detect it. Credit: Chris Hammang

The i-motif is a four-stranded knot of DNA that is very different from a double helix, where 'letters' on opposite strands recognize each other. In the i-motif knot structure, C letters on the same strand of DNA bind to each other.

To detect the i-motifs inside cells, the researchers developed a new tool -- a fragment of an antibody molecule -- that could specifically recognize and attach to i-motifs with a very high affinity. With the new tool, researchers uncovered the location of 'i-motifs' in a range of human cell lines.

"What excited us most is that we could see the green spots -- the i-motifs -- appearing and disappearing over time, so we know that they are forming, dissolving and forming again," says Dr Mahdi Zeraati, whose research underpins the study's findings.

Dr Zeraati says, "We think the coming and going of the i-motifs is a clue to what they do. It seems likely that they are there to help switch genes on or off, and to affect whether a gene is actively read or not."

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