Premium
The antibacterial toxin colicin N binds to the inner core of lipopolysaccharide and close to its translocator protein
Author(s) -
Johnson Christopher L.,
Ridley Helen,
Marchetti Roberta,
Silipo Alba,
Griffin David C.,
Crawford Lucy,
Bonev Boyan,
Molinaro Antonio,
Lakey Jeremy H.
Publication year - 2014
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.12568
Subject(s) - biology , colicin , lipopolysaccharide , toxin , microbiology and biotechnology , translocator protein , biochemistry , escherichia coli , inflammation , immunology , gene , neuroinflammation
Summary Colicins are a diverse family of large antibacterial protein toxins, secreted by and active against E scherichia coli and must cross their target cell's outer membrane barrier to kill. To achieve this, most colicins require an abundant porin (e.g. OmpF ) plus a low‐copy‐number, high‐affinity, outer membrane protein receptor (e.g. BtuB ). Recently, genetic screens have suggested that colicin N ( ColN ), which has no high‐affinity receptor, targets highly abundant lipopolysaccharide ( LPS ) instead. Here we reveal the details of this interaction and demonstrate that the ColN receptor‐binding domain ( ColN ‐ R ) binds to a specific region of LPS close to the membrane surface. Data from in vitro studies using calorimetry and both liquid‐ and solid‐state NMR reveal the interactions behind the in vivo requirement for a defined oligosaccharide region of LPS . Delipidated LPS ( LPS Δ LIPID ) shows weaker binding; and thus full affinity requires the lipid component. The site of LPS binding means that ColN will preferably bind at the interface and thus position itself close to the surface of its translocon component, OmpF . ColN is, currently, unique among colicins in requiring LPS and, combined with previous data, this implies that the ColN translocon is distinct from those of other known colicins.