DNA caught rock 'n rollin'

DNA, that marvelous, twisty molecule of life, has an alter ego, research at the University of Michigan and the University of California, Irvine, reveals.

On rare occasions, its building blocks "rock and roll," deforming the familiar double helix into a different shape.

"We show that the simple DNA double helix exists in an alternative form - for one per cent of the time - and that this alternative form is functional," said Hashim M Al-Hashimi, who is the Robert L. Kuczkowski professor of chemistry and professor of biophysics at U-M. "Together, these data suggest that there are multiple layers of information stored in the genetic code."

The findings were published online 26 January in the journal Nature.

It's been known for some time that the DNA molecule can bend and flex, something like a rope ladder, but throughout these gyrations its building blocks - called bases -remain paired up just the way they were originally described by James Watson and Francis Crick, who proposed the spiral-staircase structure in 1953.

By adapting nuclear magnetic resonance (NMR) technology, Al-Hashimi's group was able to observe transient, alternative forms in which some steps on the stairway come apart and reassemble into stable structures other than the typical Watson-Crick base pairs.