title: A natural light-driven inward proton pump.
abstract: Light-driven outward H+pumps are widely distributed in nature, converting sunlight energy into proton motive force. Here we report the characterization of an oppositely directed H+pump with a similar architecture to outward pumps. A deep-ocean marine bacterium, Parvularcula oceani, contains three rhodopsins, one of which functions as a light-driven inward H+pump when expressed in Escherichia coli and mouse neural cells. Detailed mechanistic analyses of the purified proteins reveal that small differences in the interactions established at the active centre determine the direction of primary H+transfer. Outward H+pumps establish strong electrostatic interactions between the primary H+donor and the extracellular acceptor. In the inward H+pump these electrostatic interactions are weaker, inducing a more relaxed chromophore structure that leads to the long-distance transfer of H+to the cytoplasmic side. These results demonstrate an elaborate molecular design to control the direction of H+transfers in proteins.
authors.affiliation: Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.|OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.|PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Inoue
authors.affiliation: Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.
authors.forename: Shota
authors.initials: S
authors.lastname: Ito
authors.affiliation: Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Kato
authors.affiliation: Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.
authors.forename: Yurika
authors.initials: Y
authors.lastname: Nomura
authors.affiliation: Department of Physics, Kanazawa University, Kanazawa 920-1192, Japan.|Bio-AFM Frontier Research Center, Kanazawa University, Kanazawa 920-1192, Japan.
authors.forename: Mikihiro
authors.initials: M
authors.lastname: Shibata
authors.affiliation: Department of Physics, Kanazawa University, Kanazawa 920-1192, Japan.|Bio-AFM Frontier Research Center, Kanazawa University, Kanazawa 920-1192, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Uchihashi
authors.affiliation: Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.
authors.forename: Satoshi P
authors.initials: SP
authors.lastname: Tsunoda
authors.affiliation: Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.|OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Kandori
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001419:Bacteria / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D008027:Light; D051379:Mice; D010802:Phylogeny; D017494:Proton Pumps / Q000502:physiology*; D012243:Rhodopsin; D025604:Rhodopsins, Microbial; D020123:Sirolimus / Q000031:analogs & derivatives
chemical_list: D017494:Proton Pumps; D025604:Rhodopsins, Microbial; D012243:Rhodopsin; C518022:umirolimus; D020123:Sirolimus