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Genetic material (DNA) is damaged daily due to radiation, such as solar radiation, and exposure to many substances. This kind of damage can create mutations that may lead to the onset of various diseases, including cancer. To prevent this process, the cell has several "damage control" systems. In most cases, however, they operate under an "all-or-nothing" strategy: when unable to precisely correct the damage, they stop in their tracks - bringing the genetic duplication process to a halt. The result, even more severe than the initial damage, can be cell death.
The key to life, therefore, lies in the cell's ability to "compromise," allowing genetic damage control systems to operate with a certain "sloppiness" that permits a small number of mutations to form. While this may pose a certain risk, it ensures the cell's continued existence and allows for natural selection, the driving force behind evolution.
Prof. Zvi Livneh of the Weizmann Institute's Biological Chemistry Department has discovered just such a system; it is based on a newly unveiled group of enzymes that duplicate genetic material with a certain degree of tolerance for mistakes. In other words, when they come across a strip of "spoiled" genetic material, these enzymes continue to duplicate the damaged portion despite its imperfect state - and create a mutation. Livneh claims that these enzymes, which are found both in humans and in bacteria, constitute one of the most important factors preventing unnecessary cell destruction and driving the evolutionary process. The flip side, however, is that by enabling bacteria to rapidly evolve new genetic characteristics, these enzymes are also responsible for the increasing resistance of bacteria to antibiotic drugs. A better understanding of these enzymes may open a new course of action against this growing health threat.
Prof. Zvi Livneh holds the Maxwell Ellis Professorial Chair in Biological Research. His research is supported by the Dr. Ernst Nathan Fund for Biomedical Research, the M.D. Moross Institute for Cancer Research, and the Dolfi and Lola Ebner Center for Biological Research.