Genetic interactions of broad host-range plasmid RK2: evidence for a complex replication regulon.

The kil and kor genes of RK2 are novel genetic determinants further that the kil and kor network constitutes a replication regulon, and that perhaps the function of this regulon is to ensure expression of trfA at appropriate levels. The complexity of this regulon may reflect an ability of the system to adapt to the intracellular environments of a variety of hosts. Indeed, there is tantalizing evidence that regions encoding kil or kor genes are important to host range (1,2,6,28; Schmidhauser and Helinski, pers. comm.). We are therefore hopeful that the study of these genes and the eventual determination of the molecular basis of their actions will lead to a complete understanding of the replication control and broad host range capability of IncP plasmids.