James Gumbart, Michael C. Wiener, and Emad Tajkhorshid.
Mechanics of force propagation in TonB-dependent outer membrane
transport.
Biophysical Journal, 93:496-504, 2007.
(PMC: 1896255)
GUMB2007-ET
For the uptake of scarce yet essential organometallic compounds, outer membrane transporters of Gram-negative bacteria work in concert with an energy-generating inner membrane complex, thus spanning the periplasmic space to drive active transport. Here, we examine the
interaction of TonB, an inner membrane protein, with an outer membrane transporter based upon a recent crystal structure of a TonB-
transporter complex in order to characterize two largely unknown steps of the transport cycle: how energy is transmitted from TonB to the
transporter and how energy transduction initiates transport. Simulations of TonB in complex with BtuB reveal that force applied to TonB is transmitted to BtuB without disruption of the very small connection between the two, supporting a mechanical mode of coupling. Based on the results of different pulling simulations, we propose that the force transduction instigates a partial unfolding of the pore-occluding luminal domain of the transporter, a potential step in the transport cycle. Furthermore, analysis of the electrostatic potentials and salt bridge interactions between the two proteins during the simulations hints at involvement of electrostatic forces in
long-range interaction and binding of TonB and BtuB.
Download Full Text
The manuscripts available on our site are provided for your personal
use only and may not be retransmitted or redistributed without written
permissions from the paper's publisher and author. You may not upload any
of this site's material to any public server, on-line service, network, or
bulletin board without prior written permission from the publisher and
author. You may not make copies for any commercial purpose. Reproduction
or storage of materials retrieved from this web site is subject to the
U.S. Copyright Act of 1976, Title 17 U.S.C.
