The crystal structure of a prokaryotic proton-driven fumarate transporter, the first for the diverse SLC26 transporter family, reveals a rare transmembrane-segment topology. The opposite orientation of two short central helices leads to the formation of a dipole-mediated anion-binding site, which is made alternately accessible to either side of the membrane through the rocking movement of the core and gate domains of the transporter.
- Reinhart A F Reithmeier
- Trevor F Moraes
