The 2015 Nobel Prize for Chemistry has been awarded to three scientists "for mechanistic studies of DNA repair." The Prize is shared by Tomas Lindahl of the Francis Crick Institute and Clare Hall Laboratory in the UK, Paul Modrich of Howard Hughes Medical Institute and Duke University School of Medicine and Aziz Sancar of University of North Carolina.
DNA encodes the instructions for all of the proteins in our bodies, but it's far from perfect. The genetic sequence is in constant need of repair, due to errors during cell replication, damage from UV rays, and free radicals in the body, among other things. If left unchecked, this damaged DNA can lead to various diseases, including cancer.
Fortunately, the body has a number of safeguards in place to proofread and fix these errors before they become problematic. By understanding how these processes work, they can be manipulated to do genetic modifications for medical advancement.
Each of these new Nobel laureates has pioneered research into a particular aspect of DNA repair, given a certain problem.
If free radicals or other factors damage one of the A, T, C or G bases in a DNA sequence, it needs to be pulled out and replaced with an undamaged base. A special enzyme comes and snips out the damaged base, and other factors then come in and replace it. This process is known as base excision repair, and the discovery of this process came from Tomas Lindahl.
Sometimes, the DNA replication process makes a mistake and an incorrect nucleotide is put into the sequence. This means it won't match with the one on the other side. After the mistake is found, certain enzymes take out the incorrect nucleotides and they are then replaced. Paul Modrich is credited for work into this process, known as mismatch repair.
When UV rays from the sun damage DNA, it can cause sequential thymines to bind to one another, rather than to the adenine on the other side. To repair this, enzymes not only remove the damaged thymine, but several nucleotides on either side of them as well. DNA replication components then come in and fill in the holes. This process is known as nucleotide excision repair, and this process was described by Aziz Sancar.
These processes are so fundamental to DNA function, they are now taught in basic genetics classes around the world. They are extraordinary discoveries and the honors are well-deserved.
The Nobel Prize for Literature and Peace will be announced later this week.