Featured Research

from universities, journals, and other organizations

DNA caught rock 'n rollin': On rare occasions DNA dances itself into a different shape

Date:
January 29, 2011
Source:
University of Michigan
Summary:
DNA, that marvelous, twisty molecule of life, has an alter ego, research reveals. On rare occasions, its building blocks "rock and roll," deforming the familiar double helix into a different shape.

DNA, that marvelous, twisty molecule of life, has an alter ego. On rare occasions, its building blocks "rock and roll," deforming the familiar double helix into a different shape.
Credit: Image courtesy of University of Michigan

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 percent 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 Jan. 26 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.

The question was, what were these alternative stable structures?

"Using NMR, we were able to access the chemical shifts of this alternative form," said graduate student Evgenia Nikolova. "These chemical shifts are like fingerprints that tell us something about the structure." Through careful analysis, Nikolova realized the "fingerprints" were typical of an orientation in which certain bases are flipped 180 degrees.

"It's like taking half of the stairway step and flipping it upside down so that the other face now points up," said Al-Hashimi. "If you do this, you can still put the two halves of the step back together, but now what you have is no longer a Watson-Crick base pair; it's something called a Hoogsteen base pair."

"Using computational modeling, we further validated that individual bases can roll over inside the double helix to achieve these Hoogsteen base pairs," said Ioan Andricioaei, an associate professor of chemistry at the University of California, Irvine.

Hoogsteen base pairs have previously been observed in double-stranded DNA, but only when the molecule is bound to proteins or drugs or when the DNA is damaged. The new study shows that even under normal circumstances, with no outside influence, certain sections of DNA tend to briefly morph into the alternative structure, called an "excited state."

Previous studies of DNA structure have relied mainly on techniques such as X-ray and conventional NMR, which can't detect such fleeting or rare structural changes.

"These methods do not capture alternative DNA structural forms that may exist for only a millisecond or in very little abundance, such as one percent of the time," said Al-Hashimi. "We took new solution NMR methods that previously have been used to study rare deformations in proteins and adapted them so that they could be used to study rare states in nucleic acids. Now that we have the right tools to look at these so-called excited states, we may find other short-lived states in DNA and RNA."

Because critical interactions between DNA and proteins are thought to be directed by both the sequence of bases and the flexing of the molecule, these excited states represent a whole new level of information contained in the genetic code, Al-Hashimi said.

In addition to Al-Hashimi, Nikolova and Andricioaei, the paper's authors are undergraduate student Abigail Wise and assistant professor of biological chemistry Patrick O'Brien of U-M and postdoctoral researcher Eunae Kim of the University of California, Irvine.

The researchers received funding from the National Science Foundation, the National Institutes of Health and the University of Michigan.


Story Source:

The above story is based on materials provided by University of Michigan. Note: Materials may be edited for content and length.


Journal Reference:

  1. Evgenia N. Nikolova, Eunae Kim, Abigail A. Wise, Patrick J. O’Brien, Ioan Andricioaei, Hashim M. Al-Hashimi. Transient Hoogsteen base pairs in canonical duplex DNA. Nature, 2011; DOI: 10.1038/nature09775

Cite This Page:

University of Michigan. "DNA caught rock 'n rollin': On rare occasions DNA dances itself into a different shape." ScienceDaily. ScienceDaily, 29 January 2011. <www.sciencedaily.com/releases/2011/01/110128104244.htm>.
University of Michigan. (2011, January 29). DNA caught rock 'n rollin': On rare occasions DNA dances itself into a different shape. ScienceDaily. Retrieved August 20, 2014 from www.sciencedaily.com/releases/2011/01/110128104244.htm
University of Michigan. "DNA caught rock 'n rollin': On rare occasions DNA dances itself into a different shape." ScienceDaily. www.sciencedaily.com/releases/2011/01/110128104244.htm (accessed August 20, 2014).

Share This




More Health & Medicine News

Wednesday, August 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Ebola-Hit Sierra Leone's Freetown a City on Edge

Ebola-Hit Sierra Leone's Freetown a City on Edge

AFP (Aug. 19, 2014) Residents of Sierra Leone's capital voice their fears as the Ebola virus sweeps through west Africa. Duration: 00:56 Video provided by AFP
Powered by NewsLook.com
101-Year-Old Working Man Has All The Advice You Need

101-Year-Old Working Man Has All The Advice You Need

Newsy (Aug. 19, 2014) Herman Goldman has worked at the same lighting store for almost 75 years. Find out his secrets to a happy, productive life. Video provided by Newsy
Powered by NewsLook.com
Researcher Testing on-Field Concussion Scanners

Researcher Testing on-Field Concussion Scanners

AP (Aug. 19, 2014) Four Texas high school football programs are trying out an experimental system designed to diagnose concussions on the field. The technology is in response to growing concern over head trauma in America's most watched sport. (Aug. 19) Video provided by AP
Powered by NewsLook.com
American Ebola Patient Apparently Improving, Outbreak Is Not

American Ebola Patient Apparently Improving, Outbreak Is Not

Newsy (Aug. 19, 2014) Nancy Writebol, an American missionary who contracted Ebola, is apparently getting better, according to her husband. The outbreak, however, is not. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins