RecAX53 is the most recombinogenic protein among the chimeric RecA proteins composed ofEsherichia coli RecA (RecAEc) and Pseudomonas aeruginosa RecA (RecAPa) protein fragments. We found out that RecAX53 protein is more rapid in ATP hydrolysis, dissociation from single-stranded DNA (ssDNA), SSB protein displacement from ssDNA and in association with doublestranded DNA (dsDNA), as compared with RecAEc and RecAPa proteins. These results indicate that the RecAX53 hyper-recombinogenity is caused by high dynamics of this protein - by its rapid association with and dissociation from ssDNA. The ability of RecAX53 to bind actively with dsDNA accounts for the SOS-independent mechanism of hyper-recombination used by this protein.