Open AccessStructural insight into the role of the Ton complex in energy transduction
Author(s) -
Hervé Celia,
Nicholas Noinaj,
Stanisłav D. Zakharov,
Enrica Bordig,
Istvan Botos,
Mónica Santamaría,
Travis J. Barnard,
William A. Cramer,
Roland Lloubès,
Susan K. Buchanan
Publication year - 2016
Publication title -
nature
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 15.993
H-Index - 1226
eISSN - 1476-4687
pISSN - 0028-0836
DOI - 10.1038/nature19757
Subject(s) - ton , pentamer , bacterial outer membrane , chemiosmosis , membrane , dimer , escherichia coli , crystallography , biophysics , chemistry , biology , atp synthase , biochemistry , organic chemistry , fishery , gene , enzyme
In Gram-negative bacteria, outer membrane transporters import nutrients by coupling to an inner membrane protein complex called the Ton complex. The Ton complex consists of TonB, ExbB, and ExbD, and uses the proton motive force at the inner membrane to transduce energy to the outer membrane via TonB. Here, we structurally characterize the Ton complex from Escherichia coli using X-ray crystallography, electron microscopy, double electron-electron resonance (DEER) spectroscopy, and crosslinking. Our results reveal a stoichiometry consisting of a pentamer of ExbB, a dimer of ExbD, and at least one TonB. Electrophysiology studies show that the Ton subcomplex forms pH-sensitive cation-selective channels and provide insight into the mechanism by which it may harness the proton motive force to produce energy.