PURIFICATION AND CHARACTERIZATION OF THE RECF-PROTEIN FROM BACILLUS-SUBTILIS-168

Genetic evidence suggests that the Bacillus subtilis recF gene product is involved in DNA repair and recombination. The RecF protein was ove rproduced and purified, NH2-terminal protein sequence analysis of RecF was consistent with the deduced amino acid sequence of the recF gene, The RecF protein (predicted molecular mass 42.3 kDa) bound single- ac id double-stranded DNA in a filter binding and in a gel retarding assa y The RecF-ssDNA or -dsDNA complex formation proceeds in the absence o f nucleotide cofactors. RecF-ssDNA interaction is markedly stimulated by divalent cations. The apparent equilibrium constants of the RecF-DN A complexes are similar to 110-130 nM for both ssDNA and dsDNA. The bi nding reaction shows no cooperativity. The RecF protein does not physi cally interact with the RecR protein, Under our experimental condition s an ATPase activity was not associated with the purified RecF protein or with the RecF and RecR proteins.