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Photochemical characterization of actinorhodopsin and its functional existence in the natural host
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| Title: | Photochemical characterization of actinorhodopsin and its functional existence in the natural host |
| Authors: | Nakamura, Shintaro Browse this author | | Kikukawa, Takashi Browse this author →KAKEN DB | | Tamogami, Jun Browse this author | | Kamiya, Masakatsu Browse this author | | Aizawa, Tomoyasu Browse this author | | Hahn, Martin W. Browse this author | | Ihara, Kunio Browse this author | | Kamo, Naoki Browse this author | | Demura, Makoto Browse this author |
| Keywords: | Actinorhodopsin | | Light-driven proton pump | | Phototrophy | | Photocycle | | Flash photolysis | | Microbial rhodopsin |
| Issue Date: | Dec-2016 |
| Publisher: | Elsevier |
| Journal Title: | Biochimica et Biophysica Acta (BBA) Bioenergetics |
| Volume: | 1857 |
| Issue: | 12 |
| Start Page: | 1900 |
| End Page: | 1908 |
| Publisher DOI: | 10.1016/j.bbabio.2016.09.006 |
| PMID: | 27659506 |
| Abstract: | Actinorhodopsin (ActR) is a light-driven outward H+ pump. Although the genes of ActRs are widely spread among freshwater bacterioplankton, there are no prior data on their functional expression in native cell membranes. Here, we demonstrate ActR phototrophy in the native actinobacterium. Genome analysis showed that Candidatus Rhodoluna planktonica, a freshwater actinobacterium, encodes one microbial rhodopsin (RpActR) belonging to the ActR family. Reflecting the functional expression of RpActR, illumination induced the acidification of the actinobacterial cell suspension and then elevated the ATP content inside the cells. The photochemistry of RpActR was also examined using heterologously expressed RpActR in Escherichia coli membranes. The purified RpActR showed lambda(max) at 534 nm and underwent a photocycle characterized by the very fast formation of M intermediate. The subsequent intermediate, named P-620, could be assigned to the 0 intermediate in other H+ pumps. In contrast to conventional 0, the accumulation of P620 remains prominent, even at high pH. Flash-induced absorbance changes suggested that there exists only one kind of photocycle at any pH. However, above pH 7, RpActR shows heterogeneity in the H+ transfer sequences: one first captures H+ and then releases it during the formation and decay of P-650, while the other first releases H+ prior to H+ uptake during P-620 formation. (C) 2016 Elsevier B.V. All rights reserved. |
| Rights: | ©2016. This manuscript version is made available under the CC-BY-NC-ND 4.0 license 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/2115/67766 |
| 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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