RecR is a zinc metalloprotein from Bacillus subtilis 168

The Bacillus subtilis RecR protein is required for DNA repair and recombination in vivo. In its N-terminal portion, RecR possesses potential zinc-ligand structures associated with the multicysteine (C4) superfamily. The number and arrangement of the cysteine residues is suggestive of RecR being a zinc-finger protein. One of the four cysteines (Cys-60) has been replaced by a Ser (C60S) or an Ala (C60A) residue to generate the recR60 and recR601 genes, respectively. B. subtilis recR60, recR601 or delta recR1 (a null-mutant allele) cells are 10-, 134- and 144-fold more sensitive to 10 mM methanesulphonate and 95-, 900- and 1100-fold more sensitive to the lethal effect of 100 microM 4-nitroquinoline-1-oxide (4NQO) than the wild-type strain, respectively. The RecR zinc-ligand C4 motif does not seem to be accessible, because the protein is highly resistant to oxidation and moderately resistant to reduction. We have determined by different biochemical methods that RecR is a zinc metalloprotein whose cysteine residues have a structural and/or functional role.