The recA protein of E. coli : regulation and function in recombination and repair : UV induction, autoregulatory model, DNA binding protein, DNA renaturation, strand assimilation
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In Escherichia coli, the recA function is required for general recombination, repair of DNA damage and a diverse group of functions which are coordinately expressed following DNA damage or arrest of DNA synthesis (SOS functions ). These latter functions include UV mutagenesis, W- reactivation of damaged phage DNA, prophage induction and cell filamentation. In this paper we summarize experiments which have elucidated regulatory and functional aspects of the recA gene product. Biochemical and genetic data suggest a model for control of recA gene expression in which the recA protein auto regulates its own synthesis following UV irradiation or other forms of DNA damage. The features of this autoregulatory mechanism are different from those proposed for gene 32 protein of phage T4. Biochemical experiments with homogeneous wild type and mutant forms of RecA protein reveal that this unique DNA binding protein catalyzes DNA renaturation and single strand assimilation reactions which are coupled to ATP hydrolysis. These results indicate that RecA protein catalyzes strand transfer during the initiation of genetic recombination and during post-replication repair of damaged DNA in vivo.