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 (C-4) 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 One of the four cysteines (Cys-60) has been replaced by a Ser (C60S) or an Ala (C60A) residue to generate the recR60 and recRG01 genes, respectively. B. subtilis recR60, recRG01 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 mu M 4-nitroquinoline-1-oxide (4NQO) than the wild-type strain, respectively. The RecR zinc-ligand C-4 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.