Outer Membrane Active Transport: Structure of the BtuB:TonB Complex

See allHide authors and affiliations

Science  02 Jun 2006:
Vol. 312, Issue 5778, pp. 1396-1399
DOI: 10.1126/science.1127694

You are currently viewing the abstract.

View Full Text


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 β strand that is recruited to the existing β sheet of TonB, which is consistent with a mechanical pulling model of transport.

View Full Text