KILLER GENES IN THE LEADING REGION OF CONJUGATIVE PLASMID R100 (INCFII)

Fragments of the conjugative plasmid R100 leading region were cloned. The leading region was found to contain the psiB and parB (hoklsok) ge nes. The killer phenotype was characteristic of both psiB and parB, al beit expressed only under a strong inducible promoter and in the prese nce of the inductor (IPTG). The R100 psiB gene inhibited SOS-dependent DNA repair as well as recombination (an apparent result of its RecA-i nactivating,a function). However, RecA was not involved in the psiB ki ller effect.