title: Genetics of colicin E susceptibility in citrobacter freundii.
abstract: The insensitivity of Citrobacter freundii to the E colicins is based on tolerance to colicin E1 and resistance to colicins E2 and E3. Spontaneous colicin A resistant mutants of C. freundii also lost their colicin E1 receptor function. Sensitivity to colicin E1 can be induced by F'gal+tol+ plasmids, the tol A+ gene product of which is responsible for this effect. Receptor function for colicins E2 and E3 is induced by the E. coli F'14 bfe+ plasmid, which is also able to enhance notably the receptor capacity for colicin E1. The bfe+ gene product of E. coli, which is responsible for these phenomena, also restores the receptor function for colicin A and E1 in colicin A resistant mutants of C. freundii. All results show that there is a remarkable difference between the E. coli bfe+ gene product and the bfe+ gene product of C. freundii and also between the tol A+ gene products of these strains. The sensitivity to phage BF23 parallels the sensitivity to colicins E2 and E3 and is also induced by the F'14 bfe+ plasmid.
mesh_terms: D002954:Citrobacter / Q000187:drug effects*; D003087:Colicins / Q000494:pharmacology*; D003090:Coliphages; D003429:Cross Reactions; D004352:Drug Resistance, Microbial; D004755:Enterobacteriaceae / Q000187:drug effects*; D004926:Escherichia coli; D009154:Mutation; D010641:Phenotype; D014161:Transduction, Genetic
chemical_list: D003087:Colicins