2015 Nobel Prize in Chemistry: Tomas Lindahl, Paul Modrich and Aziz Sancar

Tomas Lindahl, Paul Modrich and Aziz Sancar were on 7 October 2015 jointly awarded with the 2015 2015 Nobel Prize in Chemistry for having mapped how cells repair damaged DNA and safeguard the genetic information at a molecular level.

All the three laureates will share the prize money of 8 million Swedish kronor equally. Tomas Lindahl is from the Francis Crick Institute, UK; Paul Modrich is from Duke University School of Medicine, USA and Aziz Sancar belongs to University of North Carolina School of Medicine, USA.

Their work provided fundamental knowledge of how a living cell functions and how it is used for the development of new cancer treatments.

How cells repair damaged DNA?
Each day our DNA is damaged by UV radiation, free radicals and other carcinogenic substances, but even without such external attacks, a DNA molecule is inherently unstable. Thousands of spontaneous changes to a cell’s genome occur on a daily basis.

Defects can also arise when DNA is copied during cell division, a process that occurs several million times every day in the human body. The reason our genetic material does not disintegrate into complete chemical chaos is that a host of molecular systems continuously monitor and repair DNA.

However, these three pioneering scientists have mapped that how several repair systems function at a detailed molecular level. Tomas Lindahl demonstrated that DNA decays at a rate that ought to have made the development of life on Earth impossible. This insight led him to discover molecular machinery named Base Excision Repair which constantly counteracts the collapse of our DNA.

Aziz Sancar mapped Nucleotide Excision Repair, the mechanism that cells use to repair UV damage to DNA. People born with defects in this repair system will develop skin cancer if they are exposed to sunlight. The cell also utilises nucleotide excision repair to correct defects.

Furthermore, Paul Modrich demonstrated how the cell corrects errors that occur when DNA is replicated during cell division. This mechanism, Mismatch Repair, reduces the error frequency during DNA replication by about a thousand fold.

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