dna

Everyone knows the shape of DNA: the iconic, graceful figure-8s of the double helix. If that ladder weren’t folded into some tight, three-dimensional structure, then the code for every cell in our body would be six feet long! Obviously, that just wouldn’t do.

Until recently, scientists had assumed that DNA folds into a sphere that looks like a tangled ball of yarn (above left). With this arrangement, it would be possible for genes that are close together on the ladder to actually be quite distant in 3D space. But last month, a team of researchers from Massachusetts — including Eric Lander, one of the leaders of the Human Genome Project, and now one of Obama’s lead science advisers — reported in Science that the structure is actually much more smartly organized (above right). From the MIT news office:

This architecture, called a “fractal globule,” enables the cell to pack DNA incredibly tightly while avoiding the knots and tangles that might interfere with the cell’s ability to read its own genome. Moreover, the DNA can easily unfold and refold during gene activation, gene repression and cell replication.

“Nature’s devised a stunningly elegant solution to storing information — a super-dense, knot-free structure,” says senior author Eric Lander, director of the Broad Institute, who is also professor of biology at MIT and professor of systems biology at Harvard Medical School.

For a lot more info about how this work was done, check out Science‘s podcast interview with first author Job Dekker, of UMass.