Low resolution structure and dynamics of a colicin-receptor complex determined by neutron scattering

Luke A. Clifton, Christopher L. Johnson, Alexandra S. Solovyova, Phil Callow, Kevin L. Weiss, Helen Ridley, Anton P. Le Brun, Christian J. Kinane, John R.P. Webster, Stephen A. Holt, Jeremy H. Lakey

Research output: Contribution to journalArticlepeer-review

50 Scopus citations

Abstract

Proteins that translocate across cell membranes need to overcome a significant hydrophobic barrier. This is usually accomplished via specialized protein complexes, which provide a polar transmembrane pore. Exceptions to this include bacterial toxins, which insert into and cross the lipid bilayer itself. We are studying the mechanism by which large antibacterial proteins enter Escherichia coli via specific outer membrane proteins. Here we describe the use of neutron scattering to investigate the interaction of colicin N with its outer membrane receptor protein OmpF. The positions of lipids, colicin N, and OmpF were separately resolved within complex structures by the use of selective deuteration. Neutron reflectivity showed, in real time, that OmpF mediates the insertion of colicin N into lipid monolayers. This data were complemented by Brewster Angle Microscopy images, which showed a lateral association ofOmpF in the presence of colicin N. Small angle neutron scattering experiments then defined the three-dimensional structure of the colicin N-OmpF complex. This revealed that colicin N unfolds and binds to the OmpF-lipid interface. The implications of this unfolding step for colicin translocation across membranes are discussed.

Original languageEnglish
Pages (from-to)337-346
Number of pages10
JournalJournal of Biological Chemistry
Volume287
Issue number1
DOIs
StatePublished - Jan 2 2012

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