The X-Files DNA mystery unlocked by University of Sheffield researchers

New research by a team at the University of Sheffield has revealed how branched DNA molecules are removed from the iconic double-helical structure.

The process is essential for all life forms and is one that scientists have been trying to better understand for more than 20 years. It also inspired a plotline in the popular television series The X-Files, which recently returned to the screen.

Jon Sayers, Professor of Functional Genomics at the university and lead author of the study, said: “Branched DNA features in several episodes of the X-Files as Agent Scully suspects aliens inserted it in her blood.

“In reality, far from being of alien origin, branched DNA is formed every day in our bodies. It happens every time our cells divide.

“These branches are essential intermediates formed during the process of copying our DNA.”

During its research the team captured unique snapshots of enzymes trimming branched DNA after cell division.

The scientists found a Flap EndoNuclease enzyme (FEN) threads the free end of the branch through a hole in the enzyme. The enzyme then slides along to the trunk where it acts like a pair of molecular secateurs, trimming the branch and restoring the iconic double-helix.

Professor Sayers said: “Understanding how they work will help to engineer better and more reliable tests and tools for laboratory research and hospital diagnostics labs.

“The enzymes that carry out this process are sometimes involved in cancer. They have been linked to tumour progression and mutation, so this discovery could pave the way for better diagnostics or new drugs.

“Knowing how these enzymes work could aid development of new antimicrobial drugs.”

The research was published today in Nature Structural and Molecular Biology.