Systems that keep the genome safe earn three Nobels in chemistry

A DNA repair protein shown in two modes, patrolling undamaged DNA (in green) and bound to a DNA damage site (magenta). Once identified, other enzymes are recruited to perform repairs. (credit: Myrna Romero and Jung-Hyun Min)

The human genome is over three billion base pairs long. Even if each day carries a one-in-a-million risk of damage to a base, that means over 3,000 damaged bases every day—in each of our trillions of cells. And many things raise the risk of damage substantially, from smoking and sunlight to simply duplicating the genome when cells divide. Without a way of managing this damage, our genomes would quickly degenerate into a useless mess.

This year's Nobel in Chemistry goes to three individuals who helped clarify the role of DNA damage repair. Thomas Lindahl, currently in London, is credited for recognizing that DNA repair is an essential process and characterizing a simple repair pathway. Paul Modrich and Aziz Sancar, both in North Carolina, share the prize for their roles in identifying two major additional means of performing repair.

Lindahl's role in recognizing the need for repair is more significant than it might sound. Relative to many other complex molecules, DNA is remarkably stable. While it was recognized that it could be damaged under unusual circumstances, such as X-ray exposure, it was thought that no special actions were needed to keep genomes intact under normal conditions.