DNA Structure
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Vanderbilt University researchers have discovered a new class of DNA repair enzyme, according to findings published in the journal Nature.

After originally discovering the structure of DNA, scientists thought that it was a chemically stable blueprint of traits that was difficult to alter. However, in the decades since, scientists have found that the double helix molecule is extremely reactive and subject to damage. Cells must constantly work to repair damaged DNA, and that's where DNA repair enzymes come in.

"It's a double-edged sword," said Brandt Eichman, an associate professor of biological sciences and biochemistry at Vanderbilt and the leader of the research team behind this discovery. "If DNA were too reactive then it wouldn't be capable of storing genetic information. But, if it were too stable, then it wouldn't allow organisms to evolve."

Damaged DNA

DNA can be damaged either by environmental factors like toxins and UV radiation, or by wear and tear as a result of cell processes.

"More than 10,000 DNA damage events occur each day in every cell in the human body that must be repaired for DNA to function properly," said first author Elwood Mullins, a postdoctoral research associate in Vanderbilt's Eichman lab.

This new DNA repair enzyme, a "DNA glycosylase", is part of a family of enzymes first discovered recently by Thomas Lindahl, Ph.D. from that Francis Crick Institute in London, who was awarded this year's Nobel Prize in Chemistry on October 7th for his contribution to the DNA repair study. This family is one of about 10 DNA repair pathways identified so far—and there's still much more to be discovered, the researchers say.

"Our discovery shows that we still have a lot to learn about DNA repair, and that there may be alternative repair pathways yet to be discovered," said Eichman.

"It certainly shows us that a much broader range of DNA damage can be removed in ways that we didn't think were possible. Bacteria are using this to their advantage to protect themselves against the antibacterial agents they produce. Humans may even have DNA-repair enzymes that operate in a similar fashion to remove complex types of DNA damage.

"This could have clinical relevance because these enzymes, if they exist, could be reducing the effectiveness of drugs designed to kill cancer cells by shutting down their ability to replicate."