Damage Signals Triggering the Escherichia coli SOS Response

Failure of a cell to accurately replicate and/or repair its DNA can lead to mutations, disease, and in extreme cases, even death. Thus, it is by no means trivial that the genetic information in all cells is subject to continuous assault by DNA damaging agents. Although many DNA damaging agents exist in the environment, some, such as reactive oxygen species, are produced as metabolic byproducts by cells themselves. As a result of this chronic threat, all organisms have evolved numerous important mechanisms by which to repair or tolerate DNA damage.