Two functions of the E protein are key elements in the plasmid F replication control system.
By using a plasmid carrying a translational fusion between the E gene of the IncFI plasmid F and the lacZ gene, we located the operator of the autogenously regulated E gene to an inverted repeat overlapping the E-gene promoter and showing perfect homology to part of the sequence found in all the direct repeats of two regions exerting an inhibitory effect on F replication, incB and incC. Excess E protein provided in trans to an F plasmid increased the replication frequency of the F plasmid. This stimulatory effect was counteracted by increased dosages of incB or incC. A model is proposed for the replication control system of F in which the key elements are autoregulation of E-gene expression and titration of E protein by incB and incC.
D001426:Bacterial Proteins / Q000502:physiology*; D001483:Base Sequence; D003001:Cloning, Molecular; D004261:DNA Replication; D004269:DNA, Bacterial / Q000032:analysis; D004926:Escherichia coli / Q000235:genetics; D010957:Plasmids; D012091:Repetitive Sequences, Nucleic Acid
D001426:Bacterial Proteins; D004269:DNA, Bacterial