The DNA in our cells is constantly attacked by numerous external agents, such as carcinogenic molecules contained in tobacco smoke or UV rays emitted by the sun. Unrepaired, these attacks cause mutations that can promote the development of cancer, hence the importance of rapid and efficient DNA repair. To do this, the cell mobilizes a series of enzymes that must be perfectly coordinated to identify and repair the damaged parts of their genetic heritage. The complexity of this process has long prevented researchers to understand what were the mechanisms at work.
With the development of nanotechnology, a team consisting of biologists and physicists was able to film live enzymes in mending DNA abyss. Their series of studies was initiated in 2012 1 , when the team focused on the start of the repair mechanism. They have now for the first time, the repair process in its entirety.
With a specialized microscope, which allows both to manipulate and observe DNA molecules and proteins, researchers observed DNA molecule damaged by ultraviolet light. They added RNA polymerase, an enzyme that normally "reads" the DNA code to begin the expression on his information in the form of protein, but which "locks" being played when it arrives on a damaged part of the DNA. It is through this blockage of RNA polymerase that repairs are carried out. Specifically, the researchers could observe how a series of proteins (Mfd, UvrA, then uvrB UvrC) have succeeded, each with its specific activity, and are to contact them to interact with the RNA polymerase and repair damaged DNA by UV rays.
in determining the order in which these components act and characterizing how they take turns, these studies have established what are the critical steps of the process.
This discovery could foster new applications, the time in the fight against cancer and one against bacteria. Indeed, when the cancers are resistant to chemotherapy and radiotherapy - whose effect is to damage the DNA of cancer cells - is that their cells have just turned this DNA repair mechanism. We can consider new ways to inhibit at key mechanisms for this repair. In addition, bacteria such as the cause of tuberculosis employ very similar proteins Mfd to proliferate. Thus, having identified how these proteins interact with each other may also be useful in the fight against pathogenic bacteria.