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Functional importance of the oligomer formation of the cyanobacterial H+ pump Gloeobacter rhodopsin

発表形態:
原著論文
主要業績:
単著・共著:
発表年月:
2019年12月
DOI:
10.1038/s41598-019-47178-5
会議属性:
査読:
リンク情報:

日本語フィールド

著者:
Iizuka, Azusa; Kajimoto, Kousuke; Fujisawa, Tomotsumi; Tsukamoto, Takashi; Aizawa, Tomoyasu; Kamo, Naoki; Jung, Kwang Hwan; Unno, Masashi; Demura, Makoto; Kikukawa, Takashi
題名:
Functional importance of the oligomer formation of the cyanobacterial H+ pump Gloeobacter rhodopsin
発表情報:
Scientific Reports 巻: 9 号: 1 ページ: -
キーワード:
概要:
© 2019, The Author(s). 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.
抄録:

英語フィールド

Author:
Iizuka, Azusa; Kajimoto, Kousuke; Fujisawa, Tomotsumi; Tsukamoto, Takashi; Aizawa, Tomoyasu; Kamo, Naoki; Jung, Kwang Hwan; Unno, Masashi; Demura, Makoto; Kikukawa, Takashi
Title:
Functional importance of the oligomer formation of the cyanobacterial H+ pump Gloeobacter rhodopsin
Announcement information:
Scientific Reports Vol: 9 Issue: 1 Page: -
An abstract:
© 2019, The Author(s). 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.


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