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Photochemical characterization of actinorhodopsin and its functional existence in the natural host


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タイトル: Photochemical characterization of actinorhodopsin and its functional existence in the natural host
著者: Nakamura, Shintaro 著作を一覧する
Kikukawa, Takashi 著作を一覧する
Tamogami, Jun 著作を一覧する
Kamiya, Masakatsu 著作を一覧する
Aizawa, Tomoyasu 著作を一覧する
Hahn, Martin W. 著作を一覧する
Ihara, Kunio 著作を一覧する
Kamo, Naoki 著作を一覧する
Demura, Makoto 著作を一覧する
キーワード: Actinorhodopsin
Light-driven proton pump
Flash photolysis
Microbial rhodopsin
発行日: 2016年12月
出版者: Elsevier
誌名: Biochimica et Biophysica Acta (BBA) Bioenergetics
巻: 1857
号: 12
開始ページ: 1900
終了ページ: 1908
出版社 DOI: 10.1016/j.bbabio.2016.09.006
抄録: 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
資料タイプ: article (author version)
出現コレクション:雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

提供者: 菊川 峰志


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