title: pH-dependent gating in a FocA formate channel.
abstract: 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.
authors.affiliation: Lehrstuhl für Biochemie, Institut für organische Chemie und Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstrasse 21, 79104 Freiburg, Germany.
authors.forename: Wei
authors.initials: W
authors.lastname: Lü
authors.forename: Juan
authors.initials: J
authors.lastname: Du
authors.forename: Tobias
authors.initials: T
authors.lastname: Wacker
authors.forename: Elke
authors.initials: E
authors.lastname: Gerbig-Smentek
authors.forename: Susana L A
authors.initials: SL
authors.lastname: Andrade
authors.forename: Oliver
authors.initials: O
authors.lastname: Einsle
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D003460:Crystallization; D018360:Crystallography, X-Ray; D005561:Formates / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D015640:Ion Channel Gating; D007473:Ion Channels / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D017136:Ion Transport; D008958:Models, Molecular; D011487:Protein Conformation; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D012486:Salmonella typhimurium / Q000737:chemistry* / Q000378:metabolism; D055672:Static Electricity
chemical_list: D001426:Bacterial Proteins; D005561:Formates; D007473:Ion Channels; D021122:Protein Subunits; C030544:formic acid