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Probing the Cl--pumping photocycle of pharaonis halorhodopsin : Examinations with bacterioruberin, an intrinsic dye, and membrane potential-induced modulation of the photocycle

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Title: Probing the Cl--pumping photocycle of pharaonis halorhodopsin : Examinations with bacterioruberin, an intrinsic dye, and membrane potential-induced modulation of the photocycle
Authors: Kikukawa, Takashi Browse this author →KAKEN DB
Kusakabe, Chikara Browse this author
Kokubo, Asami Browse this author
Tsukamoto, Takashi Browse this author
Kamiya, Masakatsu Browse this author
Aizawa, Tomoyasu Browse this author
Ihara, Kunio Browse this author
Kamo, Naoki Browse this author
Demura, Makoto Browse this author →KAKEN DB
Keywords: Halorhodopsin
Carotenoid
Light-driven chloride pump
Photocycle
Flash photolysis
Microbial rhodopsin
Issue Date: Aug-2015
Publisher: Elsevier
Journal Title: Biochimica et biophysica acta-bioenergetics
Volume: 1847
Issue: 8
Start Page: 748
End Page: 758
Publisher DOI: 10.1016/j.bbabio.2015.05.002
PMID: 25960108
Abstract: Halorhodopsin (HR) functions as a light-driven inward Cl- pump. The Cl- transfer process of HR from Natronomonas pharaonis (NpHR) was examined utilizing a mutant strain, KM-1, which expresses large amount of NpHR in a complex with the carotenoid bacterioruberin (Brub). When Cl- was added to unphotolyzed Cl--free NpHR-Brub complex, Brub caused the absorption spectral change in response to the Cl- binding to NpHR through the altered electrostatic environment and/or distortion of its own configuration. During the Cl--puming photocycle, on the other hand, oppositely directed spectral change of Brub appeared during the O intermediate formation and remained until the decay of the last intermediate NpHR'. These results indicate that Cl- is released into the cytoplasmic medium during the N to O transition, and that the subsequent NpHR' still maintains an altered protein conformation while another Cl- already binds in the vicinity of the Schiff base. Using the cell envelope vesicles, the effect of the interior negative membrane potential on the photocycle was examined. The prominent effect appeared in the shift of the N-O quasi-equilibrium toward N, supporting Cl- release during the N to O transition. The membrane potential had a much larger effect on the Cl- transfer in the cytoplasmic half channel compared to that in the extracellular half channel. This result may reflect the differences in dielectric constants and/or lengths of the pathways for Cl- transfers during N to O and O to NpHR' transitions.
Rights: ©2015, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/
http://creativecommons.org/licenses/by-nc-nd/4.0/
Type: article (author version)
URI: http://hdl.handle.net/2115/62596
Appears in Collections:生命科学院・先端生命科学研究院 (Graduate School of Life Science / Faculty of Advanced Life Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 菊川 峰志

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