Nucleotide sequence of the region of an origin of replication of the antibiotic resistance plasmid R6K.

Abstract

A 2.1 kilobase segment of the antibiotic resistance plasmid R6K carries sufficient information to replicate as a plasmid in Escherichia coli. This segment contains a functional origin of replication and a structural gene for a protein, designated .pi., that is required for the initiation of R6K replication. The nucleotide sequence of a 520 base-pair portion of this 2.1 kilobase segment that includes the functional origin of replication and the region adjacent to the start of the .pi. structural gene was determined. A striking feature of the sequence is the presence of seven 22 base-pair direct repeats joined in tandem in the region adjacent to the start of the .pi. gene. A possible role of the tandem repeats in the regulation of expression of the .pi. protein and the control of initiation of replication of the plasmid R6K is discussed.