Incompatibility between bacteriophage lambda and the sex factor F

Defective lambda plasmids, either λdv or λN, interfere with the replication of the Escherichia coli sex factor F. The incompatibility between these two plasmids is considered due to the P protein of lambda, since non-lambda replicons into which the lambda P gene has been cloned inhibit F replication. The inhibitory effect of the P protein on F replication is reduced in bacteria with the dnaB mutation grpB. This implies that the interference by lambda P protein is mediated, at least in part, through the E. coli dnaB product.