'DNA wires' could help physicians diagnose disease

August 19, 2012

In a discovery that defies the popular meaning of the word "wire," scientists have found that Mother Nature uses DNA as a wire to detect the constantly occurring genetic damage and mistakes that ― if left unrepaired ― can result in diseases like cancer and underpin the physical and mental decline of aging.

That topic ― wires and their potential use in identifying people at risk for certain diseases ― is the focus of a plenary talk during the 244th National Meeting & Exposition of the American Chemical Society, the world's largest scientific society.

"DNA is a very fragile and special wire," said Jacqueline K. Barton, Ph.D., who delivered the talk. "You're never going to wire a house with it, and it isn't sturdy enough to use in popular electronic devices. But that fragile state is exactly what makes DNA so good as an electrical biosensor to identify DNA damage."

Barton won the U.S. National Medal of Science, the nation's highest honor for scientific achievement, for discovering that cells use the double strands of the DNA helix like a wire for signaling, which is critical to detecting and repairing . She is a professor of chemistry and is chair of the division of chemistry and chemical engineering at the California Institute of Technology in Pasadena.

Damage is constantly occurring to DNA, Barton explained ― damage that skin cells, for instance, receive from excessive exposure to sunlight or that lung cells get hit with from carcinogens in cigarette smoke. Cells have a natural repair system in which special proteins constantly patrol the spiral-staircase architecture of DNA. They monitor the 3 billion units, or "base pairs," in DNA, looking for and mending damage from carcinogens and other sources.

Barton and other scientists noticed years ago that the DNA architecture chemically resembles the solid-state materials used in transistors and other electronic components. And DNA's bases, or units, are stacked on top of each other in an arrangement that seemed capable of conducting electricity.

"It's like a stack of copper pennies," said Barton. "And when in good condition and properly aligned, that stack of copper pennies can be conductive. But if one of the pennies is a little bit awry ― if it's not stacked so well ― then you're not going to be able to get good conductivity in it. But if those bases are mismatched or if there is any other damage to the DNA, as can happen with damage that leads to cancer, the wire is interrupted and electricity will not flow properly."

Barton's team established that the electrons that comprise a flow of electricity can move from one end of a DNA strand to the other, just as they do through an electrical wire. In one recent advance, the team was able to send electricity down a 34-nanometer-long piece of DNA. That might not sound like much — a nanometer is one-tenth the width of a human hair. But that is just the right scale for use in medical diagnostic devices and biosensors to pick up on mutations, or changes, in DNA that could lead to cancer and other diseases.

Barton's research suggested that DNA uses its electrical properties to signal repair proteins that fix DNA damage. If the DNA is no longer conducting electricity properly, that would be a signal for repair proteins to do their thing. Barton's team is applying that knowledge in developing "DNA chips," devices that take advantage of DNA's natural electrical conductivity and its ability to bind to other strands of DNA that have a complementary sequence of base units, and thus probe that sequence for damage. Such a DNA chip would help diagnose disease risk by changes in electrical conductivity resulting from mutations or some other damage.

Related Stories

Molecular corkscrew

November 8, 2011

Scientists from the universities of Zurich and Duisburg-Essen have discovered a specific function of the protein p97/VCP. They demonstrate that the protein repairs DNA breaks like a corkscrew, a repair mechanism that could ...

Recommended for you

Crystal clear images uncover secrets of hormone receptors

July 31, 2015

Many hormones and neurotransmitters work by binding to receptors on a cell's exterior surface. This activates receptors causing them to twist, turn and spark chemical reactions inside cells. NIH scientists used atomic level ...

A cheaper, high-performance prosthetic knee

July 30, 2015

In the last two decades, prosthetic limb technology has grown by leaps and bounds. Today, the most advanced prostheses incorporate microprocessors that work with onboard gyroscopes, accelerometers, and hydraulics to enable ...

Flow means 'go' for proper lymph system development

July 27, 2015

The lymphatic system provides a slow flow of fluid from our organs and tissues into the bloodstream. It returns fluid and proteins that leak from blood vessels, provides passage for immune and inflammatory cells from the ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.