RecA Protein


The RecA protein of Escherichia coli is the prototypic deoxyribonucleic acid (DNA) strand exchange protein. It assembles on single‐stranded DNA to form a helical nucleoprotein filament that is the active species for all RecA protein‐dependent functions. This protein–DNA complex is responsible for three mutually exclusive functions: DNA recombination, induction of the DNA‐damage SOS response and SOS‐induced mutagenesis.

Keywords: DNA strand exchange; genetic recombination; SOS response; SOS mutagenesis; nucleoprotein filament; LexA repressor

Figure 1.

Roles of the RecA nucleoprotein filament in DNA metabolism. A schematic showing the three mutually exclusive functions of the RecA protein filament. Adapted from Rehrauer et al..

Figure 2.

The nucleoprotein filament formed by RecA protein. (a) A filament formed on dsDNA with ATPγS as cofactor (from Stasiak and Egelman ). The striations in the filament indicate the groove discussed in the text. Scale bar 0.1 nm. (b) Closeup of the filament (the DNA is not visible) shown in (a). The asterisks indicate the lobes of monomers that protrude into the groove and the white arrow indicates the smooth surface of the groove. (c, d) Cross‐sections of the filament showing a single turn. (b,c) Three‐dimensional reconstructions of electron micrographs of RecA filaments formed on dsDNA with ATPγS. (d) Single turn of the RecA filament as seen in the crystal structure (Story et al., ). The individual monomers are coloured alternately in orange and yellow. The numbers in (c,d) indicate the six monomers making up the turn in the cross‐section; the DNA would be located in the central hole, but is not shown.

Figure 3.

Functional map of the RecA protein. RecA protein is presented as a linear amino acid sequence. There are eight highly conserved subdomains found in all RecA protein homologues. These are highlighted in green, and the amino acids corresponding to each domain are shown at the top of each domain. The conservation index (CI) for each subdomain is shown in the grey box. A CI=1.00 indicates that this region is invariant in all RecA protein homologues. The combined index is a combined analysis of all RecA protein homologues and the number shown is not an average CI of the eubacterial, eukaryotic and archaeal conservation indices. The functional domains of RecA protein are highlighted in the peach box. The regions involved in DNA binding (black), ATP binding (orange), the monomer–monomer (M–M) interface (blue) and filament–filament interactions (cerise) are displayed.

Figure 4.

The DNA strand exchange reaction promoted by the RecA protein. RecA protein is represented as round dots and ssDNA‐binding (SSB) protein as squares. The three stages shown are presynapsis, synapsis and DNA heteroduplex extension. Adapted from Bianco et al..



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Further Reading

Anderson DG and Kowalczykowski SC (1998) Reconstitution of an SOS response pathway: derepression of transcription in response to DNA breaks. Cell 95: 975–979.

Eggleston AK and West SC (1996) Exchanging partners: recombination in E. coli. Trends in Genetics 12: 20–26.

Friedberg EC, Walker GC and Siede W (1995) DNA Repair and Mutagenesis. Washington, DC: ASM Press.

Goodman MF (2002) Error‐prone repair DNA polymerases in prokaryotes and eukaryotes. Annual Review of Biochemistry 71: 17–50.

Kowalczykowski SC (1991) Biochemistry of genetic recombination: energetics and mechanism of DNA strand exchange. Annual Review of Biophysics and Biophysical Chemistry 20: 539–575.

Kowalczykowski SC and Eggleston AK (1994) Homologous pairing and DNA strand‐exchange proteins. Annual Review of Biochemistry 63: 991–1043.

Kowalczykowski SC, Dixon DA, Eggleston AK, Lauder SD and Rehrauer WM (1994) Biochemistry of homologous recombination in Escherichia coli. Microbiological Reviews 58: 401–465.

Roca AI and Cox MM (1997) RecA protein: structure, function, and role in recombinational DNA repair. Progress in Nucleic Acid Research and Molecular Biology 56: 129–223.

Stasiak A and Egelman EH (1988) Visualization of recombination reactions. In: Kucherlapati R and Smith GR (eds) Genetic Recombination, pp. 265–308. Washington, DC: ASM Press

Walker GC (1996) The SOS response of Escherichia coli. In: Neidhardt FC and Curtiss R (eds) Escherichia coli and Salmonella: Cellular and Molecular Biology, vol. 1, pp. 1400–1416. Washington, DC: ASM Press

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Bianco, Piero R, and Kowalczykowski, Stephen C(Sep 2005) RecA Protein. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1038/npg.els.0003925]