DNA repair and its relation to cell division in E. coli

In E. coli, lesions introduced by agents such as UV radiation, chemical agents, thymine starvation, lead to the induction of a series of bacterial fonctions called the "SOS response" (DNA reparation, mutagenesis, filamentation, prophages induction etc...). Genetics and biochemical study set up the evidences of a regulated mechanism. The central effector of this mechanism is the Rec A protéin. When a cell's DNA is damaged or its DNA replication is inhibited, an inducing signal is generated. The inducing signal reversebly activates a specific protease activity of Rec A which allows it to cleave the Lex A repressor. Thus inducing operons repressed by Lex A. These operons are implicated in DNA reparations and also in cellular division. A coordination between reparation and cellular division is thus established.