It's DNA, but not as we know it. In a world first, Australian researchers have identified a new DNA structure - called the “i-motif” - inside cells. A twisted “knot” of DNA, the i-motif has never before been directly seen inside living cells. The new findings, from the Garvan Institute of Medical Research, were published online on April 23, 2018 in Nature Chemistry. The article is titled “I-Motif DNA Structures Are Formed in the Nuclei of Human Cells.” Deep inside the cells in our body lies our DNA. The information in the DNA code - all 6 billion A, C, G, and T letters - provides precise instructions for how our bodies are built, and how they work. The iconic “double helix” shape of DNA has captured the public imagination since 1953, when James Watson and Francis Crick famously uncovered the structure of DNA. However, it's now known that short stretches of DNA can exist in other shapes, in the laboratory at least - and scientists suspect that these different shapes might play an important role in how and when the DNA code is “read.” The new shape looks entirely different from the double-stranded DNA double helix. "When most of us think of DNA, we think of the double helix," says Associate Professor Daniel Christ (Head, Antibody Therapeutics Lab, Garvan) who co-led the research. "This new research reminds us that totally different DNA structures exist - and could well be important for our cells." "The i-motif is a four-stranded 'knot' of DNA," says Associate Professor Marcel Dinger (Head, Kinghorn Centre for Clinical Genomics, Garvan), who co-led the research with Assistant Professor Christ.
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