Zoom-in: the Proton Relay Network.

Original View: Spacefill, Color by Group

Campylobacter jejuni antibiotic-resistance is mediated by multiple mechanisms. CmeB is a homotrimeric, inner-membrane efflux pump that contributes significantly to antibiotic resistance in C. jejuni.

The Cme tripartite system consists of the CmeB  pump, the CmeA periplasmic adaptor, and the CmeC outer-membrane channel.

Each chain has a distinct Drug-Binding Domain (DBD) that opens a channel to bind drugs from the periplasm, and then closes to extrude them up through the pump's central pore. Notice the dangling loop in the center; this loop gates access to the channel.

In each protomer, the conserved residues D409, D410, and K935 form a salt-bridge triad, and establish a proton relay network that powers the protein's conformational changes.

Structures and Transport Dynamics of Campylobacter jejuni Multidrug Efflux Pump.

Chih-Chia Su et al. Nature Communications (Nature)

5LQ3 (PDB)

Next page: Conformational Changes throughout Drug Transport

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