| Title: | Interhelical interactions between D92 and C218 in the cytoplasmic domain regulate proton uptake upon N-decay in the proton transport of Acetabularia rhodopsin II |
| Authors: | Tamogami, Jun Browse this author |
| Kikukawa, Takashi Browse this author |
| Ohkawa, Keisuke Browse this author |
| Ohsawa, Noboru Browse this author |
| Nara, Toshifumi Browse this author |
| Demura, Makoto Browse this author |
| Miyauchi, Seiji Browse this author |
| Kimura-Someya, Tomomi Browse this author |
| Shirouzu, Mikako Browse this author |
| Yokoyama, Shigeyuki Browse this author |
| Shimono, Kazumi Browse this author |
| Kamo, Naoki Browse this author |
| Keywords: | Microbial rhodopsin |
| Proton pump |
| Photocycle |
| Hydrogen bond |
| Switching |
| Issue Date: | Jun-2018 |
| Publisher: | Elsevier |
| Journal Title: | Journal of photochemistry and photobiology B-biology |
| Volume: | 183 |
| Start Page: | 35 |
| End Page: | 45 |
| Publisher DOI: | 10.1016/j.jphotobiol.2018.04.012 |
| Abstract: | Acetabularia rhodopsin II (ARII or Ace2), an outward light-driven algal proton pump found in the giant unicellular marine alga Acetabularia acetabulum, has a unique property in the cytoplasmic (CP) side of its channel. The X-ray crystal structure of ARII in a dark state suggested the formation of an interhelical hydrogen bond between C218(ARII) and D92(ARII), an internal proton donor to the Schiff base (Wada et al., 2011). In this report, we investigated the photocycles of two mutants at position C218(ARII): C218(AAII) which disrupts the interaction with D92(ARII), and C218S(ARII) which potentially forms a stronger hydrogen bond. Both mutants exhibited slower photocycles compared to the wild-type pump. Together with several kinetic changes of the photoproducts in the first half of the photocycle, these replacements led to specific retardation of the N-to-O transition in the second half of the photocycle. In addition, measurements of the flash-induced proton uptake and release using a pH sensitive indium-tin oxide electrode revealed a concomitant delay in the proton uptake. These observations strongly suggest the importance of a native weak hydrogen bond between C218(ARII) and D92(ARII) for proper proton translocation in the CP channel during N-decay. A putative role for the D92(ARII)-C218(ARII) interhelical hydrogen bond in the function of ARII is discussed. |
| Rights: | ©2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ |
| https://creativecommons.org/licenses/by-nc-nd/4.0/ |
| Type: | article (author version) |
| URI: | http://hdl.handle.net/2115/78774 |
| 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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