Researchers identify new form of DNA in living cells

In a world first Australian-led study published researchers have identified a new DNA structure inside living cells.

Referred to as “i-motif” by the Garvan Institute of Medical Research, the new DNA structure is shaped as a four-stranded “knot” which is completely different to the well-known “double helix” DNA shape that was first discovered in 1953.

“When most of us think of DNA, we think of the double helix,” Associate Professor Daniel Christ, who co-led the research said.

“This new research reminds us that totally different DNA structures exist and could well be important for our cells.”

Although the “knot DNA” has previously been seen before outside of living cells under artificial conditions in a laboratory, many scientists debated whether the i-motif could exist inside living things.

But by using a fragment of an antibody molecule that could specifically recognise and attach to the i-motifs, Christ and his team located the structure in a range of human cell lines.

Scientists suggest that i-motifs predominantly generates during the late G1 phase of a cell’s life cycle, when DNA is being actively “read.”

It’s believed the i-motifs also appears in telomeres, a compound structure at the end of a chromosome, and has a crucial role to play in the ageing process.

“We think the coming and going of the i-motifs is a clue to what they do,” first author of the study Dr Mahdi Zeraati said.
“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.”