Characterization of the stability functions and inverted repeat structure X3 of the IncFI plasmid ColV2-K94

A region of the IncFI plasmid ColV2-K94 which showed homology to the sop partitioning genes of F was cloned and characterized in an attempt to study the stability functions of this element. The sop region contained the incD incompatibility determinant common to many IncFI plasmids, but could not confer on ColV2-K94 miniplasmids the same stable inheritance found in the intact ColV2-K94; thus, other functions appear to be required for efficient plasmid maintenance. Adjacent to the area of sop homology was the X3 region, which was found to contain three inverted IS1-like sequences. The X3 region of ColV2-K94 was similar in organization to the aerobactin iron uptake region of ColV3-K30, but ColV2-K94 lacked the ability to synthesize either the aerobactin siderophore or its outer membrane receptor.