It’s been nearly 60 years since the structure of DNA was found to be a double helix. Now, researchers at the University of Cambridge have found that “quadruple helix” DNA structures can also be found in the human genome.

A new study, published this week in the journal Nature Chemistry, shows that the structures, called G-quadruplexes, form in DNA regions that are rich in the nucleobase guanine. The research also found that the quadruplexes are linked to the process of DNA replication.

“We are seeing links between trapping the quadruplexes with molecules and the ability to stop cells dividing, which is hugely exciting,” said Shankar Balasubramanian, a professor in the University of Cambridge’s Department of Chemistry. “The research indicates that quadruplexes are more likely to occur in genes of cells that are rapidly dividing, such as cancer cells. For us, it strongly supports a new paradigm to be investigated – using these four-stranded structures as targets for personalized treatments in the future.”

Though scientists have in the past been able to show that quadruplex DNA can form in the lab, this is the first time that the structures have been shown to form in nature. The Cambridge researchers suggest that synthetic molecules that trap quadruplexes could be used in the future to halt the proliferation of cancer.

“We have found that by trapping the quadruplex DNA with synthetic molecules we can sequester and stabilise them, providing important insights into how we might grind cell division to a halt,” said Balasubramanian. “There is a lot we don’t know yet. One thought is that these quadruplex structures might be a bit of a nuisance during DNA replication – like knots or tangles that form. Did they evolve for a function? It’s a philosophical question as to whether they are there by design or not – but they exist and nature has to deal with them. Maybe by targeting them we are contributing to the disruption they cause.”

(Image courtesy the University of Cambridge)