CLONING AND SEQUENCING OF A CHROMOSOMAL FRAGMENT FROM CLOSTRIDIUM-ACETOBUTYLICUM STRAIN ABKN8 CONFERRING CHEMICAL-DAMAGING AGENTS AND UV RESISTANCE TO ESCHERICHIA-COLI RECA STRAINS

A 3.3-kb DNA fragment of Clostridium acetobutylicum conferred methyl m ethane sulfonate (MMS), mitomycin C (MC), and UV resistance to recA st rains off. coli when cloned on the pUC19 plasmid. Analysis of the nucl eotide sequence of the total insert and results of in vitro transcript ion-translation experiments showed that the insert directed the synthe sis of three polypeptides referred to as ORFa, ORFb, and ORFc of 23.6, 15.3, and 21 kDa, respectively. None of the polypeptides presented a relationship with the RecA protein off. coli or products of genes invo lved in the SOS response. The deduced amino acid sequence of ORFb and ORFc are highly homologous to those deduced from two genes specifying resistance to tellurium salts present on plasmid pMER610 harbored by A lcaligenes sp.strains and to an AMP-binding protein (CABP1) found in D ictyostelium discoideum. The existence of these homologous proteins su ggests that they may perform a similar key function in the three unrel ated organisms.