Outer membrane active transport: structure of the BtuB:TonB complex |
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Authors: | Shultis David D Purdy Michael D Banchs Christian N Wiener Michael C |
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Institution: | Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA. |
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Abstract: | In Gram-negative bacteria, the import of essential micronutrients across the outer membrane requires a transporter, an electrochemical gradient of protons across the inner membrane, and an inner membrane protein complex (ExbB, ExbD, TonB) that couples the proton-motive force to the outer membrane transporter. The inner membrane protein TonB binds directly to a conserved region, called the Ton-box, of the transporter. We solved the structure of the cobalamin transporter BtuB in complex with the C-terminal domain of TonB. In contrast to its conformations in the absence of TonB, the Ton-box forms a beta strand that is recruited to the existing beta sheet of TonB, which is consistent with a mechanical pulling model of transport. |
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