title: A single mutation converts bacterial Na(+) -transporting rhodopsin into an H(+) transporter.
abstract: Na(+) -rhodopsins are light-driven pumps used by marine bacteria to extrude Na(+) ions from the cytoplasm. We show here that replacement of Gln123 on the cytoplasmic side of the ion-conductance channel with aspartate or glutamate confers H(+) transport activity to the Na(+) -rhodopsin from Dokdonia sp. PRO95. The Q123E variant could transport H(+) out of Escherichia coli cells in a medium containing 100 mm Na(+) and SCN(-) as the penetrating anion. The rates of the photocycle steps of this variant were only marginally dependent on Na(+) , and the major electrogenic steps were the decays of the K and O intermediates.
authors.affiliation: Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Russia.
authors.forename: Mahir D
authors.initials: MD
authors.lastname: Mamedov
authors.affiliation: Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Russia.
authors.forename: Adalyat M
authors.initials: AM
authors.lastname: Mamedov
authors.affiliation: Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Russia.
authors.forename: Yulia V
authors.initials: YV
authors.lastname: Bertsova
authors.affiliation: Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Russia.
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Bogachev
mesh_terms: D001224:Aspartic Acid / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D041965:Flavobacteriaceae / Q000235:genetics / Q000378:metabolism*; D018698:Glutamic Acid / Q000378:metabolism; D006859:Hydrogen / Q000378:metabolism*; D017136:Ion Transport / Q000235:genetics; D007477:Ions / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D025604:Rhodopsins, Microbial / Q000235:genetics / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*
chemical_list: D007477:Ions; D026901:Membrane Transport Proteins; D025604:Rhodopsins, Microbial; D001224:Aspartic Acid; D018698:Glutamic Acid; D006859:Hydrogen; D012964:Sodium
keywords: Pump-to-pump conversion; rhodopsin; sodium transport