Separation of the minimal replication region of the F plasmid into a replication origin segment and a trans-acting segment.

An analysis was carried out on the replication functions within a 2.3 kilobase (kb) segment of the F plasmid which contains an origin (ori s) of replication and is capable of autonomous replication in Escherichia coli. Two separable regions were delineated for this segment: an origin region of approximately 1,140 bp in length and a segment of approximately 1,140 bp that functions in trans to support replication of the origin region. The trans-acting segment is functional as part of an F replicon or when inserted into the E. coli chromosome. A prominent feature of the trans-acting segment is a coding sequence for a 29 K protein (Murotsu et al. 1981).