Chemistry and Physics Faculty Articles
Title
Allosteric Signaling Is Bidirectional in an Outer-Membrane Transport Protein
Document Type
Article
Publication Date
11-1-2016
Publication Title
Biophysical Journal
ISSN
0006-3495
Volume
111
Issue/No.
9
First Page
1908
Last Page
1918
Abstract
In BtuB, the Escherichia coli TonB-dependent transporter for vitamin B12, substrate binding to the extracellular surface unfolds a conserved energy coupling motif termed the Ton box into the periplasm. This transmembrane signaling event facilitates an interaction between BtuB and the inner-membrane protein TonB. In this study, continuous-wave and pulse electron paramagnetic resonance in a native outer-membrane preparation demonstrate that signaling also occurs from the periplasmic to the extracellular surface in BtuB. The binding of a TonB fragment to the periplasmic interface alters the configuration of the second extracellular loop and partially dissociates a spin-labeled substrate analog. Moreover, mutants in the periplasmic Ton box that are transport-defective alter the binding site for vitamin B12 in BtuB. This work demonstrates that the Ton box and the extracellular substrate binding site are allosterically coupled in BtuB, and that TonB binding may initiate a partial round of transport.
Additional Comments
NIH grant #: GM035215; Deutsch Forschungsgemeinschaft grant #: SFB 807
NSUWorks Citation
Sikora, A., Joseph, B., Matson, M., Staley, J. R., & Casifo, D. S. (2016). Allosteric Signaling Is Bidirectional in an Outer-Membrane Transport Protein. Biophysical Journal, 111, (9), 1908 - 1918. https://doi.org/10.1016/j.bpj.2016.09.038. Retrieved from https://nsuworks.nova.edu/cnso_chemphys_facarticles/212
DOI
10.1016/j.bpj.2016.09.038
Comments
©2016 Biophysical Society.