Scientists have discovered how a network of repair proteins enables bacteria to prioritise the repair of the most heavily used regions of the DNA molecules that carry the instructions necessary for living cells to function.
The research, carried out by academics at the University of Bristol and published in Molecular Cell (Dec. 2010), reveals that there are greater similarities between the DNA repair systems of bacteria and humans than had been suspected.
When the chemical "letters" in a cell's DNA book of instructions are damaged the instructions become difficult to read and the cell may not function properly. For example, exposure to too much sunshine increases the risk of skin cancer because the ultraviolet light present in sunshine damages the DNA in skin cells and can cause them to grow in an abnormal way.
Because it is impossible to avoid DNA damage, cells have evolved many mechanisms for repairing their damaged genomes. Like council crews repairing damaged roads these DNA repair mechanisms employ individuals with different specialities: sometimes all that is needed is a small patch on the DNA, like filling in a pothole, other times large sections of the DNA need to be removed entirely and replaced.
The repair systems need molecular machines that can detect the DNA damage in the first place, machines that can cut away the damaged DNA, and machines that can finish the repair by building new undamaged DNA. All of these molecular machines must work together in an organised fashion to carry out these very intricate repairs, and so they also require machines that take the part of foreman and co-ordinate the work of the others.
When DNA is heavily damaged, cells from humans to bacteria ensure the sections that are being read at that moment (in a process called transcription) are repaired before sections that aren't being read.
A team led by Dr. Nigel Savery from the DNA-Protein interactions Unit in
|Contact: Caroline Clancy|
University of Bristol