The effect of chromosome transfer on gene expression in Escherichia coli Hfr

Abstract

The induction of β-galactosidase has been examined in crosses of Hfr with an i^s recipient. Under these conditions, the expression of the gene z in the donor alone is measured. The results show that the activity of z undergoes a transient cessation at the same time as the gene is being transferred to the F^−d and that subsequent resumption of enzyme synthesis is dependent on replication of DNA in the Hfr. We infer that single stranded regions at the growing point of replication are unable to support transcription and that replication and transcription cannot occur simultaneously.