How does DNA, the delicate blueprint of life, keep from falling apart despite repeated assaults? On Wednesday, the Nobel Prize in Chemistry went to three scientists who unraveled some of the secrets. Tomas Lindahl, Paul L. Modrich and Aziz Sancar were awarded the prize for having discovered how cells repair their DNA and protect it from waves of punishment that the body and the environment dish out more or less continuously.
The three pioneers “have explained the basic mechanisms that help to guard the integrity of our genomes,” Claes Gustafsson, chairman of the Nobel chemistry committee, told reporters in Stockholm.
Dr. Lindahl, 77, of the Francis Crick Institute and Clare Hall Laboratory, near London, was honored for discovering how cells generally fix DNA damage. Dr. Modrich, 69, of the Howard Hughes Medical Institute and Duke University School of Medicine, was recognized for showing how cells correct mistakes in DNA replication during cell division. Dr. Sancar, also 69, of the University of North Carolina, Chapel Hill, was cited for mapping how cells repair DNA damage from ultraviolet light.
In interviews posted on the Nobel Prize website, the laureates reflected on the awards. Dr. Lindahl said it was nice “to have recognition that what you have done is actually important.” Dr. Modrich was vacationing in New Hampshire when he got the news. “I was stunned,” he said, joking that he had no regrets at being unable to attend a campus news conference. “I’m in the right place at the right time.”
Dr. Sancar, the first Turkish-born scientist to win the prize, said it would prompt big celebrations his native land. “I’m glad for my country,” he said. The human body is made up of trillions of living cells, each containing a coiled mass of DNA that if straightened out would extend about six feet. In turn, each strand carries the thousands of genetic instructions needed to run the body.
But the DNA molecule is unstable. The genome of each cell undergoes thousands of spontaneous changes each day. And DNA copying for cell division and multiplication, which happens in the body millions of times daily, also introduces defects. Finally, DNA is damaged by ultraviolet light from the sun as well as by industrial pollutants and natural toxins — those in cigarette smoke, for example. What fights pandemonium are DNA repair mechanisms. Independently, the new laureates discovered a number of restorative steps.
In the early 1970s, Dr. Lindahl defied orthodoxy about DNA stability by showing that the complex molecule, on its own, would deteriorate so rapidly that life on Earth would have been impossible. That insight led him to uncover a molecular system that constantly counteracts DNA collapse.
Dr. Sancar mapped out how cells repair DNA damage from ultraviolet light. People born with defects in this system, if exposed to sunlight, develop skin cancer. Dr. Modrich showed how cellular machinery fixes errors that arise during DNA replication, reducing the frequency of mistakes by roughly a thousand. Defects in this system cause a hereditary variant of colon cancer.
Experts say the insights are likely to aid the development of new treatments for cancer as well as ills related to aging. Dr. Lindahl said the advances should help society learn how to “convert diseases into something we can live with.”
The Royal Swedish Academy of Sciences, which awarded the prize, called the work of the three laureates “a decisive contribution to the understanding of how the living cell functions, as well as providing knowledge about the molecular causes of several hereditary diseases and about mechanisms behind both cancer development and aging.”
Diane Grob Schmidt, president of the American Chemical Society, based in Washington, called the award a demonstration of research strength in the United States given that two of the three laureates work on American campuses.
