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GEN News Highlights : Apr 12, 2010

Scientists Find Protein that Aids in Repairing Double-Strand Breaks in DNA

Ku allows for much more accurate repair than previously believed, according to study in Nature.

A protein called Ku is particularly adept at healing damaged strands of DNA, according to investigators at the University of North Carolina at Chapel Hill's Lineberger Comprehensive Cancer Center. In fact, they found that Ku employs a unique mechanism to repair double-strand breaks.

The study is published in Nature in a paper titled “Ku is a 5'-dRP/AP lyase that excises nucleotide damage near broken ends.”

“Damage to DNA in the form of a broken chromosome, or double-strand break, can be very difficult to repair as it is not a clean break and areas along the strand may be damaged at the level of the fundamental building blocks of DNA called nucleotides,” explains Dale Ramsden, Ph.D., associate professor in the department of biochemistry and biophysics and a member of the curriculum in genetics and molecular biology.

These rough ends get “dirty” making them harder to repair. “It has been assumed in the past that double-strand breaks are the most difficult class of DNA damage to repair, and it is often presumed that they simply can not be repaired accurately.”

Dr. Ramsden’ team found that Ku, which has long been appreciated for its ability to find chromosome breaks along a strand of DNA, actually removes the “dirt” at broken chromosome ends, allowing for much more accurate repair than previously believed.

“This protein actually heals at the nucleotide level as well as the level of the chromosome,” Dr. Ramsden points out. The team is hopeful that the discovery of this mechanism for DNA repair may lead to a target for the treatment of age-related diseases caused by chromosome damage in the future.