Scientists discover new DNA structure called i-motif

Scientists have discovered a new DNA structure that is inside human cells and have dubbed the structure "i-motif." I-motif resembles a twisted knot of DNA rather than the double helix were all learned about in school. This type of DNA had been suggested by previous lab work, but this is the first time that i-motif has been directly observed in living cells.

As of now, the scientists don't exactly know the purpose that i-motif serves. The thought is that the structure help in the "reading" process of DNA sequences and in converting them into useful substances. In the past, i-motif had been observed in artificial conditions in labs, but it was unclear from that work if such structures existed in living cells.

While double helix DNA is made up of base parings using bases called adenine, thymine, cytosine, and guanine; i-motif is a four-stranded knot of DNA. In this structure the cytosine letters on the same strand of DNA bind to each other. In the double helix DNA, these bases can only pair with specific bases such as cytosine pairing with guanine and thymine pairing with adenine.

Scientist used probes that use Y-shaped antibodies that bind with specific substances, in this case specifically to i-motifs but not any other form of DNA. Fluorescent dyes were added to the antibody probed so they location of i-motifs in cells could be monitored.

In the research, green spots appeared in the nuclei of each of three different types of human cells they looked at. Scientists note that the green spots of i-motifs appeared and disappeared over time. They think this disappearing act is a clue to the purpose of i-motifs in the cells. Speculation is they are there to switch genes on or off and to affect if a gene is actively read or not.

SOURCE: Independent