The recombinase RecA plays a crucial role in homologous recombination and the SOS response in bacteria. Although recA mutants usually are defective in homologous recombination and grow poorly, they nevertheless can be isolated in almost all bacteria. Previously, considerable difficulties were experienced by several laboratories in generating recA null mutations in Streptomyces, and the only rec...

The SOS response, a set of cellular phenomena exhibited by eubacteria, is initiated by various causes that include DNA damage-induced replication arrest, and is positively regulated by the co- protease activity of RecA. Escherichia coli DinI, a LexA-regulated SOS gene product, shuts off the initiation of the SOS response when overexpressed in vivo. Biochemical and genetic studies indicated that...

recA protein binding to duplex DNA is a complicated, multistep process. The final product of this process is a stably bound complex of recA protein and extensively unwound double-stranded DNA. recA monomers within the complex hydrolyze ATP with an apparent kcat of approximately 19-22 min-1. Once the final binding state is achieved, binding and ATP hydrolysis by this complex becomes pH independe...

The nucleotide sequence of the L pneumophila recA gene was determined. The coding region was 1044 nucleotides (348 codons), specifying a 37,934 Da protein. Preceding the recA gene was a tandem set of transcription regulatory sequences and putative LexA binding sites. When expressed in E. coli, the cloned recA gene yield two proteins with molecular weights of approximately 38,000 and 35,500 Da. ...

Stalled replication forks are sites of chromosome breakage and the formation of toxic recombination intermediates that undermine genomic stability. Thus, replication fork repair and reactivation are essential processes. Among the many models of replication fork reactivation is one that invokes fork regression catalyzed by the strand exchange protein RecA as an intermediate in the processing of ...

Escherichia coli recA protein catalyzes a specific proteolytic cleavage of repressors in vitro when it is activated by interaction with a single-stranded polynucleotide and nucleoside triphosphate. The ATP analogue adenosine-5'-O-(3-thiotriphosphate) (ATP gamma S) satisfies the NTP requirement. We show here that despite its activity in repressor cleavage, ATP gamma S is hydrolyzed at a negligib...

The inducible SOS response increases the ability of bacteria to cope with DNA damage through various DNA repair processes in which the RecA protein plays a central role. Here we present the first study of the morphological aspects that accompany the SOS response in Escherichia coli. We find that induction of the SOS system in wild-type bacteria results in a fast and massive intracellular coaggr...

RecBCD enzyme facilitates loading of RecA protein onto ssDNA produced by its helicase/nuclease activity. This process is essential for RecBCD-mediated homologous recombination. Here, we establish that the C-terminal nuclease domain of the RecB subunit (RecBnuc) forms stable complexes with RecA. Interestingly, RecBnuc also interacts with and loads noncognate DNA strand exchange proteins. Interac...

Expression of the bacterial RecA protein in plants stimulates homologous recombination in tobacco. Here we show that RecA plays a direct role in DNA strand exchange in vivo. The number of sister chromatid exchanges (SCEs) was increased 2.4-fold over wild type in transgenic tobacco plants expressing a nuclear-targeted RecA (nt-RecA) protein and could not be increased further by DNA damage, which...

In vitro recombination reactions promoted by the recA protein of Escherichia coli are enhanced by the single-stranded DNA binding protein (SSB). SSB affects the assembly of the filamentous complexes between recA protein and ssDNA that are the active form of the recA protein. Here, we present evidence that SSB plays a complex role in maintaining the stability and activity of recA-ssDNA filaments...