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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)
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Submitter: 菊川 峰志
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