‘Supercoiled’ DNA puts the simple double helix to shame

minivector

October 13

When most of us think of DNA, we think of that iconic double helix shape. But when you zoom out, DNA gets a lot more complicated.

“When Watson and Crick described the DNA double helix, they were looking at a tiny part of a real genome, only about one turn of the double helix,” University of Leeds researcher Sarah Harris says. “This is about 12 DNA ‘base pairs,’ which are the building blocks of DNA that form the rungs of the helical ladder.”

[Gene editing could make pig-to-human organ transplants a reality]

(Thana Sutthibutpong)Harris is one of the lead authors of a study, published Monday in Nature Communications, that imaged the intricate formations of DNA and used computer simulations to examine how they wiggle and change.

“Our study looks at DNA on a somewhat grander scale — several hundreds of base pairs — and even this relatively modest increase in size reveals a whole new richness in the behavior of the DNA molecule,” Harris said in a statement.

The 3 billion base pairs that make up human DNA — about three feet worth of the stuff — has to cram into the nucleus of each and every human cell. So it’s no surprise that things get pretty twisted.

The researchers observed a complex variety of shapes and found that they changed and moved constantly. Because drugs work by binding to the specific shape of a molecule, the researchers hope that their work will help develop better pharmaceuticals.

“We are sure that supercomputers will play an increasingly important role in drug design. We are trying to do a puzzle with millions of pieces, and they all keep changing shape,” Harris said.

Reference

Irobalieva RN, Fogg JM, Catanese DJ, Sutthibutpong T, Chen M, Barker AK, Ludtke SJ, Harris SA, Schmid MF, Chiu W, Zechiedrich L. (2015) Structural Diversity of supercoiled DNA. Nature Comm [Epub ahead of print]. [article]

Source – The Washington Post