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Role of Arg-72 of pharaonis Phoborhodopsin (sensory rhodopsin II) on its photochemistry.
| Title: | Role of Arg-72 of pharaonis Phoborhodopsin (sensory rhodopsin II) on its photochemistry. |
| Authors: | Ikeura, Yukako Browse this author | | Shimono, Kazumi Browse this author | | Iwamoto, Masayuki Browse this author | | Sudo, Yuki Browse this author | | Kamo, Naoki Browse this author |
| Keywords: | pKa of the counterion of the Schiff base | | M-decay rate | | M-formation rate | | Proton uptake and release | | Proton releasing group |
| Issue Date: | May-2004 |
| Publisher: | The Biophysical Society |
| Journal Title: | Biophysical Journal |
| Volume: | 86 |
| Issue: | 5 |
| Start Page: | 3112 |
| End Page: | 3120 |
| PMID: | 15111424 |
| Abstract: | Pharaonis phoborhodopsin (ppR, or pharaonis sensory rhodopsin II, NpsRII) is a sensor for the negative phototaxis of Natronomonas (Natronobacterium) pharaonis. Arginine 72 of ppR corresponds to Arg-82 of bacteriorhodopsin, which is a highly conserved residue among microbial rhodopsins. Using various Arg-72 ppR mutants, we obtained the following results: 1), Arg-72ppR together possibly with Asp-193 influenced the pKa of the counterion of the protonated Schiff base. 2), The M-rise became approximately four times faster than the wild-type. 3), Illumination causes proton uptake and release, and the pH profiles of the sequence of these two proton movements were different between R72A mutant and the wild-type; it is inferred that Arg-72 connects the proton transfer events occurring at both the Schiff base and an extracellular proton-releasing residue (Asp-193). 4), The M-decays of Arg-72 mutants were faster (8–27 folds at pH 8 depending on mutants) than the wild-type, implying that the guanidinium prevents the proton transfer from the extracellular space to the deprotonated Schiff base. 5), The proton-pumping activities were decreased for mutants having increased M-decay rates, but the extent of the decrease was smaller than expected. The role of Arg-72 of ppR on the photochemistry was discussed. |
| Type: | article (author version) |
| URI: | http://hdl.handle.net/2115/16000 |
| Appears in Collections: | 薬学研究院 (Faculty of Pharmaceutical Sciences) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
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Submitter: 加茂 直樹
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