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Reisomerization of retinal represents a molecular switch mediating Na+ uptake and release by a bacterial sodium-pumping rhodopsin

発表形態:
原著論文
主要業績:
主要業績
単著・共著:
共著
発表年月:
2022年08月
DOI:
会議属性:
指定なし
査読:
有り
リンク情報:

日本語フィールド

著者:
T. Fujisawa, K. Kinoue, R. Seike, T. Kikukawa, M. Unno
題名:
Reisomerization of retinal represents a molecular switch mediating Na+ uptake and release by a bacterial sodium-pumping rhodopsin
発表情報:
J. Biol. Chem. 296, 100792 (2022)
キーワード:
概要:
抄録:
Sodium-pumping rhodopsins (NaRs) are membrane transporters that utilize light energy to pump Na+ across the cellular membrane. Within the NaRs, the retinal Schiff base chromophore absorbs light, and a photochemically-induced transient state, referred to as the “O intermediate”, performs both the uptake and release of Na+. However, the structure of the O intermediate remains unclear. Here, we used time-resolved cryo-Raman spectroscopy under preresonance conditions to study the structure of the retinal chromophore in the O intermediate of a NaR from the bacterium Indibacter alkaliphilus. We observed two O intermediates, termed O1 and O2, having distinct chromophore structures. We show O1 displays a distorted 13-cis chromophore, while O2 contains a distorted all-trans structure. This finding indicated that the uptake and release of Na+ are achieved not by a single O intermediate, but by two sequential O intermediates that are toggled via isomerization of the retinal chromophore. These results provide crucial structural insight into the unidirectional Na+ transport mediated by the chromophore-binding pocket of NaRs.

英語フィールド

Author:
T. Fujisawa, K. Kinoue, R. Seike, T. Kikukawa, M. Unno
Title:
Reisomerization of retinal represents a molecular switch mediating Na+ uptake and release by a bacterial sodium-pumping rhodopsin
Announcement information:
J. Biol. Chem. 296, 100792 (2022)
An abstract:
Sodium-pumping rhodopsins (NaRs) are membrane transporters that utilize light energy to pump Na+ across the cellular membrane. Within the NaRs, the retinal Schiff base chromophore absorbs light, and a photochemically-induced transient state, referred to as the “O intermediate”, performs both the uptake and release of Na+. However, the structure of the O intermediate remains unclear. Here, we used time-resolved cryo-Raman spectroscopy under preresonance conditions to study the structure of the retinal chromophore in the O intermediate of a NaR from the bacterium Indibacter alkaliphilus. We observed two O intermediates, termed O1 and O2, having distinct chromophore structures. We show O1 displays a distorted 13-cis chromophore, while O2 contains a distorted all-trans structure. This finding indicated that the uptake and release of Na+ are achieved not by a single O intermediate, but by two sequential O intermediates that are toggled via isomerization of the retinal chromophore. These results provide crucial structural insight into the unidirectional Na+ transport mediated by the chromophore-binding pocket of NaRs.


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