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The unstructured domain of colicin N kills E scherichia coli
Author(s) -
Johnson Christopher L.,
Ridley Helen,
Pengelly Robert J.,
Salleh Mohd Zulkifli,
Lakey Jeremy H.
Publication year - 2013
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12260
Subject(s) - colicin , biology , bacterial outer membrane , escherichia coli , bacteria , peptide , cytotoxic t cell , microbiology and biotechnology , cell membrane , biochemistry , biophysics , membrane , genetics , in vitro , gene
Summary Bacteria often produce toxins which kill competing bacteria. Colicins, produced by and toxic to E scherichia coli bacteria are three‐domain proteins so efficient that one molecule can kill a cell. The C ‐terminal domain carries the lethal activity and the central domain is required for surface receptor binding. The N ‐terminal domain, required for translocation across the outer membrane, is always intrinsically unstructured. It has always been assumed therefore that the C ‐terminal cytotoxic domain is required for the bactericidal activity. Here we report the unexpected finding that in isolation, the 90‐residue unstructured N ‐terminal domain of colicin N is cytotoxic. Furthermore it causes ion leakage from cells but, unlike known antimicrobial peptides ( AMPs ) with this property, shows no membrane binding behaviour. Finally, its activity remains strictly dependent upon the same receptor proteins ( OmpF and TolA ) used by full‐length colicin N . This mechanism of rapid membrane disruption, via receptor mediated binding of a soluble peptide, may reveal a new target for the development of highly specific antibacterials.