Plasmid cloning vehicles derived from plasmids ColE1, F, R6K, and RK2.

Publisher Summary This chapter discusses the cloning vehicles related to plasmids ColE1, F, R6K, and RK2. Because these replicons have different properties, cloning vehicles derived from one of them may be more suitable for a particular application than vehicles derived from another. Also, because derivatives of a single plasmid do not stably coexist, it is often desirable to have available cloning vehicles from a variety of incompatibility groups to study the interactions among cloned fragments. The ColE1 vehicles pMK20, pMK16, and pMK2004 are very useful for general-purpose cloning because they are maintained in high copy number and provide good selective markers for transformation. Like the ColE1 vehicles, pRK353, a derivative of the antibiotic resistance plasmid R6K, is present in a large number of copies per cell and can be used as a high-copy-number cloning vehicle that can coexist with ColE1. In addition, the R6K replicon has been separated into two components that make up a functional replicon. Plasmid RK2 is unusual because it is maintained in a wide variety of gram-negative bacteria, and therefore RK2 derivatives may be of use as cloning vehicles in gram-negative bacteria other than Escherichia coli ( E. coli ).