DNA-dependent ATPase involved in processing of recombination intermediates, plays a role in repairing DNA breaks. Stimulates the branch migration of RecA-mediated strand transfer reactions, allowing the 3' invading strand to extend heteroduplex DNA faster. Binds ssDNA in the presence of ADP but not other nucleotides, has ATPase activity that is stimulated by ssDNA and various branched DNA structures, but inhibited by SSB. Does not have RecA's homology-searching function (PubMed:26845522). Genetic experiments involving combination of radA mutations with mutations in recA, recB, recG, recJ, recQ, ruvA and ruvC show it plays a role in recombination and recombinational repair, probably involving stabilizing or processing branched DNA or blocked replication forks. Is genetically synergistic to RecG and RuvABC (PubMed:12446634, PubMed:25484163). May be involved in recovery of genetic rearrangements during replication fork breakdown (PubMed:16904387). In combination with RadD is important in recovery from double-strand DNA breaks (DSB) (PubMed:25425430). Part of the serB-radA operon (PubMed:1327967). Has a putative N-terminal zinc-finger, a region with homology to RecA with ATPase motifs including the RadA KNRFG motif (approximately residues 60-290), while the C-terminus is homologous to Lon protease (from about residue 290 to the end, the ribosomal S5 domain). In this organism the Lon protease active site Ser-372 is conserved, but not all other bacteria encode Ser at this position (PubMed:1327967, PubMed:8759876). Mutation of Ser-372 has no discernible effect on RadA function, suggesting RadA is not a protease (PubMed:25484163). Increased sensitivity to methyl methanesulfonate, mitomycin C, phleomycin (PubMed:1327967, PubMed:12446634). Has a modest defect in RecA-mediated conjugational DNA recombination; double radA-radD mutants have wild-type levels (PubMed:25425430, PubMed:12446634). 10- to 1000-fold decrease in survival after ionising irradiation (IR) (PubMed:25049088, PubMed:25425430). Double radA-radD deletions have nearly 10(6)-fold lower survival against IR and the double mutant is more severely affected by UV radiation than either of the single mutants alone. The single mutation is more sensitive to dsDNA breaks induced by ciprofloxacin (CFX), the double radA-radD mutant is inviable upon CFX treatment; the SOS response is slightly induced in the single and more induced in the double mutant (PubMed:25425430). Another group showed very slight sensitivity to CFX, UV and azidothymidine (AZT) in single deletion mutants, a radA-recG deletion is extremely sensitive to CFX and AZT, less so to UV. The SOS response is induced in the radA-recG double mutant, indicating spontaneous DNA damage. AZT sensitivity is suppressed by further recA or recF deletions, suggesting AZT-induced DNA gaps are processed into lethal intermediates in a RecA-dependent fashion mediated by RecF. RuvAB suppresses UV, CFX and AZT sensitivity to vaarying degrees. Similarly, radA-uvrD double deletions are also more sensitive to UV, CFX and AZT. Adding a recF mutation almost completely suppresses AZT and partially suppresses UV and CFX sensitivity, suggesting RadA processes a class of intermediates that accumulates in uvrD mutants (PubMed:25484163). Belongs to the RecA family. RadA subfamily.