Featured series 
Campus & Community
Repairing DNA damage
Faulty parts are found, trapped, and replacements are installed
Scientists have discovered some fascinating details about a handy repair service in your genes that that not much is known about. It searches through the huge amounts of DNA in the core of every human cell and recognizes parts that have become damaged due to the wear and tear of life. Then it removes and helps replace the faulty part without you being aware of it.
For the first time, researchers at Harvard University have taken snapshots of one of these protective “mechanics” at work. It’s a protein that checks out parts known as “bases,” the building blocks of DNA, which makes up our genes and carries the blueprints for our biology and behavior.
“Every second of every hour of every lifetime, such proteins search through millions of bases looking for errors,” notes Gregory Verdine, Erving Professor of Chemistry. “These proteins work like a jukebox, removing bases (disks) from a stack one at a time to check their labels. It’s quite a task to check through a couple hundred disks, so imagine what it would be like to inspect 10 million of them to find a particular one. That’s what DNA repair enzymes have to do. Their search-and-rescue mission is a marvel of nature’s design.” (Enzymes are proteins that make chemical changes without undergoing changes in themselves.)
After three years of difficult laboratory experiments, Verdine and his colleagues Anirban Banerjee, Wei Yang, and Martin Karplus managed to capture a series of pictures showing one of the enzymes at work. The enzyme boasts a long technical name that scientists shorten to “OGG1.”
As described in the April 1 issue of the scientific journal Nature, OGG1 moves up and down long segments of DNA looking for aberrations in a base known as guanine. If everything is normal, the enzyme moves on. But if it detects an abnormal mutation, or change, it removes the damaged part. Other enzymes then follow up and install a replacement.
“Accumulations of such mutations may eventually lead to cancer,” Verdine points out. Also, some evidence exists that they are involved in premature aging.
