RecA Protein

Abstract

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. The overall structure and activity of the nucleoprotein filament are determined by nucleoside triphosphate (NTP) cofactor binding, hydrolysis and product release. This is evident when the crystal structure of the filament is closely examined and NTP‐related structural changes are related to biological function. Key Concepts RecA protein is the prototype enzyme for a family of proteins known as recombinases. Homologous recombination is the exchange of the corresponding stretches of DNA between two DNA molecules of similar sequence. The SOS response is an inducible DNA repair and damage tolerance system that is induced by RecA. SOS‐induced mutagenesis is a form of DNA repair catalysed by error‐prone, translesion DNA polymerases. The RecA nucleoprotein filament is a large dynamic structure whose formation is essential to all RecA functions. Coprotease activity is the induced self‐cleavage of one protein (LexA) by another (RecA).