title: The immunity and lysis genes of ColN plasmid pCHAP4.
abstract: Nucleotide sequencing of part of the plasmid pCHAP4, which encodes the ca. 42,000 Da putative poreforming colicin N, confirmed previous results indicating that the colicin N immunity gene (cni) and the colicin release or lysis gene (cnl) are located immediately downstream from the colicin N structural gene (cna) in the order cna-cni-cnl. The cni gene is transcribed in the opposite direction to cna and probably encodes an Mr 15239 Da protein. The putative immunity protein was detected among the [35S]methionine-labelled proteins produced by minicells carrying cni cloned under lac promoter control, and when the gene was subcloned into expression vectors under the control of a bacteriophage T7 promoter. Deletion of the region immediately upstream from cni completely abolished colicin N immunity, presumably because the natural promoter had been deleted. cnl is in the same operon as cna, and encodes a typical Col plasmid pro-lysis protein comprising a signal peptide and a 34 residue mature polypeptide with high homology to all but one of the other known Col lysis proteins, including the fatty acylated amino-terminal cysteine residue which was specifically labelled with 3H-palmitate. Cell fractionation studies indicated that the cnl gene product was located predominantly in the outer membrane.
authors.affiliation: Unité de Génétique Moléculaire, Institut Pasteur, Paris, France.
authors.forename: A P
authors.initials: AP
authors.lastname: Pugsley
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003087:Colicins / Q000235:genetics* / Q000276:immunology; D004926:Escherichia coli / Q000235:genetics* / Q000276:immunology; D005796:Genes; D005798:Genes, Bacterial; D005814:Genes, Viral; D008242:Lysogeny; D008969:Molecular Sequence Data; D010957:Plasmids; D011401:Promoter Regions, Genetic; D013604:T-Phages / Q000235:genetics*
chemical_list: D003087:Colicins