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Replaceability of Schiff base proton donors in light-driven proton pump rhodopsins
| Title: | Replaceability of Schiff base proton donors in light-driven proton pump rhodopsins |
| Authors: | Sasaki, Syogo Browse this author | | Tamogami, Jun Browse this author | | Nishiya, Koki Browse this author | | Demura, Makoto Browse this author | | Kikukawa, Takashi Browse this author →KAKEN DB |
| Issue Date: | Sep-2021 |
| Publisher: | Elsevier |
| Journal Title: | Journal of Biological Chemistry (JBC) |
| Volume: | 297 |
| Issue: | 3 |
| Start Page: | 101013 |
| Publisher DOI: | 10.1016/j.jbc.2021.101013 |
| Abstract: | Many H+-pump rhodopsins conserve "H+ donor" residues in cytoplasmic (CP) half channels to quickly transport H+ from the CP medium to Schiff bases at the center of these proteins. For conventional H+ pumps, the donors are conserved as Asp or Glu but are replaced by Lys in the minority, such as Exi-guobacterium sibiricum rhodopsin (ESR). In dark states, carboxyl donors are protonated, whereas the Lys donor is deprotonated. As a result, carboxyl donors first donate H+ to the Schiff bases and then capture the other H+ from the me-dium, whereas the Lys donor first captures H+ from the me-dium and then donates it to the Schiff base. Thus, carboxyl and Lys-type H+ pumps seem to have different mechanisms, which are probably optimized for their respective H+-transfer re-actions. Here, we examined these differences via replacement of donor residues. For Asp-type deltarhodopsin (DR), the embedded Lys residue distorted the protein conformation and did not act as the H+ donor. In contrast, for Glu-type proteo-rhodopsin (PR) and ESR, the embedded residues functioned well as H+ donors. These differences were further examined by focusing on the activation volumes during the H+-transfer re-actions. The results revealed essential differences between archaeal H+ pump (DR) and eubacterial H+ pumps PR and ESR. Archaeal DR requires significant hydration of the CP channel for the H+-transfer reactions; however, eubacterial PR and ESR require the swing-like motion of the donor residue rather than hydration. Given this common mechanism, donor residues might be replaceable between eubacterial PR and ESR. |
| Type: | article |
| URI: | http://hdl.handle.net/2115/83253 |
| 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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