Introduction to RecA

The RecA protein is involved in at least three distinct biological processes in E. coli:

• Homologous recombination (and the recombinational repair of DNA damage).
• DNA damage induced mutagenesis.
• Activation of the SOS system.

The RecA protein of E. coli has many distinct biochemical activties including:

• DNA binding (both single and double stranded).
• Pairing and exchange of homologous DNA.
• ATP hydrolysis.
• Coproteolytic cleavage of LexA, UmuD, and the lambda repressor.

Homologs of RecA have also been found in other species.

• RecA homologs have been cloned from many bacterial species. The sequence and function of RecA is highly conserved among bacteria.
• In eukaryotes: the Rad51, Rad57, Rad55 and DMC1 proteins
• In Archaea: RadA and RadB proteins.
• In phage T4: the UvsX protein.

In addition, since there is a crystal structure available of the E. coli RecA protein and since there are 100s of studies of the effects of different mutations on the multiple functions of the protein, I believe RecA can become a model for the studies of protein-structure evolution.