Jump to Main Content
pH-Dependent Gating in a FocA Formate Channel
- Lü, Wei, Du, Juan, Wacker, Tobias, Gerbig-Smentek, Elke, Andrade, Susana L.A., Einsle, Oliver
- Science 2011 v.332 no.6027 pp. 352-354
- Salmonella Typhimurium, crystal structure, electrophysiology, formates, pH, protein subunits, protons
- The formate transporter FocA was described to switch its mode of operation from a passive export channel at high external pH to a secondary active formate/H⁺ importer at low pH. The crystal structure of Salmonella typhimurium FocA at pH 4.0 shows that this switch involves a major rearrangement of the amino termini of individual protomers in the pentameric channel. The amino-terminal helices open or block transport in a concerted, cooperative action that indicates how FocA is gated in a pH-dependent way. Electrophysiological studies show that the protein acts as a specific formate channel at pH 7.0 and that it closes upon a shift of pH to 5.1.