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Functional importance of the oligomer formation of the cyanobacterial H+ pump Gloeobacter rhodopsin
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Title: | Functional importance of the oligomer formation of the cyanobacterial H+ pump Gloeobacter rhodopsin |
Authors: | Iizuka, Azusa Browse this author | Kajimoto, Kousuke Browse this author | Fujisawa, Tomotsumi Browse this author →KAKEN DB | Tsukamoto, Takashi Browse this author →KAKEN DB | Aizawa, Tomoyasu Browse this author →KAKEN DB | Kamo, Naoki Browse this author | Jung, Kwang-Hwan Browse this author | Unno, Masashi Browse this author →KAKEN DB | Demura, Makoto Browse this author →KAKEN DB | Kikukawa, Takashi Browse this author →KAKEN DB |
Issue Date: | 24-Jul-2019 |
Publisher: | Nature Publishing Group |
Journal Title: | Scientific reports |
Volume: | 9 |
Start Page: | 10711 |
Publisher DOI: | 10.1038/s41598-019-47178-5 |
PMID: | 31341208 |
Abstract: | Many microbial rhodopsins self-oligomerize, but the functional consequences of oligomerization have not been well clarified. We examined the effects of oligomerization of a H+ pump, Gloeobacter rhodopsin (GR), by using nanodisc containing trimeric and monomeric GR. The monomerization did not appear to affect the unphotolyzed GR. However, we found a significant impact on the photoreaction: The monomeric GR showed faint M intermediate formation and negligible H+ transfer reactions. These changes reflected the elevated pKa of the Asp121 residue, whose deprotonation is a prerequisite for the functional photoreaction. Here, we focused on His87, which is a neighboring residue of Asp121 and conserved among eubacterial H+ pumps but replaced by Met in an archaeal H+ pump. We found that the H87M mutation removes the "monomerization effects": Even in the monomeric state, H87M contained the deprotonated Asp121 and showed both M formation and distinct H+ transfer reactions. Thus, for wild-type GR, monomerization probably strengthens the Asp121-His87 interaction and thereby elevates the pKa of Asp121 residue. This strong interaction might occur due to the loosened protein structure and/or the disruption of the interprotomer interaction of His87. Thus, the trimeric assembly of GR enables light-induced H+ transfer reactions through adjusting the positions of key residues. |
Rights: | https://creativecommons.org/licenses/by/4.0/ |
Type: | article |
URI: | http://hdl.handle.net/2115/75386 |
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) 国際連携研究教育局 : GI-CoRE (Global Institution for Collaborative Research and Education : GI-CoRE) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
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