Identification of pKM101-encoded loci specifying potentially lethal gene products.

Two pKM101-encoded loci (designated kilA and kilB) have been identified which elaborate products that are potentially lethal to the bacterial cell. The lethal effects of each of these products is inhibited by two other plasmid-encoded loci, designated korA and korB (for kil override). Both korA and korB are required to control the lethality of either kil gene. In the presence of korA and korB both kil genes have other phenotypes: kilB is necessary for conjugal transfer, whereas kilA is responsible for the small-colony morphology on defined media that is characteristic of pKM101-containing strains (the Slo phenotype).