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Low Resolution Structure and Dynamics of a Colicin-Receptor Complex Determined by Neutron Scattering

Lookup NU author(s): Dr Christopher Johnson, Dr Alexandra Solovyova, Anton Le Brun, Professor Jeremy Lakey

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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 of OmpF 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.


Publication metadata

Author(s): Clifton LA, Johnson CL, Solovyova AS, Callow P, Weiss KL, Ridley H, Le Brun AP, Kinane CJ, Webster JRP, Holt SA, Lakey JH

Publication type: Article

Publication status: Published

Journal: Journal of Biological Chemistry

Year: 2012

Volume: 287

Issue: 1

Pages: 337-346

Print publication date: 02/01/2012

ISSN (print): 0021-9258

Publisher: American Society for Biochemistry and Molecular Biology, Inc.

URL: http://dx.doi.org/10.1074/jbc.M111.302901

DOI: 10.1074/jbc.M111.302901

Notes: Both L.A. Clifton and C.L. Johnson contributed equally to this work.


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