When people think of DNA, they visualize a string-like double helix structure. In reality, the DNA double helix in cells is supercoiled and constrained into loops. This supercoiling and looping are known to influence every aspect of DNA activity, but how this happens has not been clear.
Published in the journal Nature Communications, a study by researchers at Baylor College of Medicine shows that supercoiling and looping can transmit mechanical stress along the DNA backbone. The stress can promote the separation of the strands of the double helix at specific distant sites, exposing the DNA bases, which may facilitate repair, replication, transcription or other aspects of DNA function.
“DNA stores a cell’s genetic information in a stable and protected form that is readily accessible for the cell to carry on its activities,” said corresponding author Dr. Lynn Zechiedrich, Kyle and Josephine Morrow Chair in molecular virology and microbiology at Baylor. “Organisms achieve this seemingly paradoxical goal by storing DNA in supercoiled loops. In the current study, we investigated how supercoiling and looping modulate DNA activity.”
