title: Structural basis for Na(+) transport mechanism by a light-driven Na(+) pump.
abstract: Krokinobacter eikastus rhodopsin 2 (KR2) is the first light-driven Na(+) pump discovered, and is viewed as a potential next-generation optogenetics tool. Since the positively charged Schiff base proton, located within the ion-conducting pathway of all light-driven ion pumps, was thought to prohibit the transport of a non-proton cation, the discovery of KR2 raised the question of how it achieves Na(+) transport. Here we present crystal structures of KR2 under neutral and acidic conditions, which represent the resting and M-like intermediate states, respectively. Structural and spectroscopic analyses revealed the gating mechanism, whereby the flipping of Asp116 sequesters the Schiff base proton from the conducting pathway to facilitate Na(+) transport. Together with the structure-based engineering of the first light-driven K(+) pumps, electrophysiological assays in mammalian neurons and behavioural assays in a nematode, our studies reveal the molecular basis for light-driven non-proton cation pumps and thus provide a framework that may advance the development of next-generation optogenetics.
authors: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.
authors: Hideaki E
authors: HE
authors: Kato
authors: 1] Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan [2] OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan [3] PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
authors: Keiichi
authors: K
authors: Inoue
authors: Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.
authors: Rei
authors: R
authors: Abe-Yoshizumi
authors: Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.
authors: Yoshitaka
authors: Y
authors: Kato
authors: Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.
authors: Hikaru
authors: H
authors: Ono
authors: Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.
authors: Masae
authors: M
authors: Konno
authors: 1] Department of Developmental Biology and Neuroscience, Tohoku University Graduate School of Life Sciences, Sendai 980-8577, Japan [2] CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
authors: Shoko
authors: S
authors: Hososhima
authors: 1] Department of Developmental Biology and Neuroscience, Tohoku University Graduate School of Life Sciences, Sendai 980-8577, Japan [2] CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
authors: Toru
authors: T
authors: Ishizuka
authors: 1] Department of Developmental Biology and Neuroscience, Tohoku University Graduate School of Life Sciences, Sendai 980-8577, Japan [2] CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
authors: Mohammad Razuanul
authors: MR
authors: Hoque
authors: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.
authors: Hirofumi
authors: H
authors: Kunitomo
authors: Department of Bioengineering Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
authors: Jumpei
authors: J
authors: Ito
authors: Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564, Japan.
authors: Susumu
authors: S
authors: Yoshizawa
authors: RIKEN SPring-8 Center, Hyogo 679-5148, Japan.
authors: Keitaro
authors: K
authors: Yamashita
authors: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.
authors: Mizuki
authors: M
authors: Takemoto
authors: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.
authors: Tomohiro
authors: T
authors: Nishizawa
authors: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.
authors: Reiya
authors: R
authors: Taniguchi
authors: Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564, Japan.
authors: Kazuhiro
authors: K
authors: Kogure
authors: Department of Bioengineering Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
authors: Andrés D
authors: AD
authors: Maturana
authors: 1] Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan [2] CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
authors: Yuichi
authors: Y
authors: Iino
authors: 1] Department of Developmental Biology and Neuroscience, Tohoku University Graduate School of Life Sciences, Sendai 980-8577, Japan [2] CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
authors: Hiromu
authors: H
authors: Yawo
authors: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.
authors: Ryuichiro
authors: R
authors: Ishitani
authors: 1] Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan [2] OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.
authors: Hideki
authors: H
authors: Kandori
authors: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.
authors: Osamu
authors: O
authors: Nureki
mesh_terms: D001665:Binding Sites; D018360:Crystallography, X-Ray; D041965:Flavobacteriaceae / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D016623:Ion Pumps / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects*; D017136:Ion Transport / Q000235:genetics / Q000528:radiation effects; D008027:Light; D008954:Models, Biological; D008958:Models, Molecular; D016296:Mutagenesis / Q000235:genetics; D062308:Optogenetics; D011188:Potassium / Q000378:metabolism; D011487:Protein Conformation; D015202:Protein Engineering; D012172:Retinaldehyde / Q000737:chemistry / Q000378:metabolism; D012243:Rhodopsin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects*; D012545:Schiff Bases; D012964:Sodium / Q000378:metabolism*; D013329:Structure-Activity Relationship
chemical_list: D016623:Ion Pumps; D012545:Schiff Bases; D012243:Rhodopsin; D012964:Sodium; D012172:Retinaldehyde; D011188:Potassium