RecA

• UniProt: P0A7G6

RecA is a 38 kilodalton protein in Escherichia coli, which plays a role in the repair and maintenance of DNA. It has been, in which searched in all species then, a homologue to E. coli RecA found. The homologous protein of human Rad51 is.

RecA has several functions, all. Associated with DNA repair It has co- protease function in the autocatalytic cleavage of the LexA repressor during the SOS response of prokaryotes. In homologous recombination, the RecA binds tightly and in long groups on single-stranded DNA ( ssDNA = single beach DNA ) and thus forms a nucleoprotein. RecA protein has more than one DNA - binding site, and can thus hold together a single strand and a double strand. This capability enables the catalysis of hydrolysis and subsequent ligation between a DNA double helix and a homologous region of single-stranded DNA.

RecA ssDNA filament searching for homologies along the double-stranded DNA. The double stranded DNA is stretched, thereby improving the detection of the homologies. This process is called conformational proofreading. The reaction favors the exchange of DNA strands between two recombining DNA double helices. After the reaction, the so-called heteroduplex region, a process begins, which is branch migration ( to German, branch transfer ') called. Here, an unpaired region of a ssDNA replaces a paired region of another ssDNA, the branch point is moved while maintaining the base pair number.

In laboratory strains of Escherichia coli RecA mutants are used, since a recombination of the plasmids often is avoided for transformation.