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Role of Asp193 in chromophore-protein interaction of pharaonis phoborhodopsin (sensory rhodopsin II).

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タイトル: Role of Asp193 in chromophore-protein interaction of pharaonis phoborhodopsin (sensory rhodopsin II).
著者: Iwamoto, Masayuki 著作を一覧する
Furutani, Yuji 著作を一覧する
Sudo, Yuki 著作を一覧する
Shimono, Kazumi 著作を一覧する
Kandori, Hideki 著作を一覧する
Kamo, Naoki 著作を一覧する
キーワード: hydrogen bonding network
anion binding
pKa of Schiff base
spectroscopic titration
sensory rhodopsin II
archaeal rhodopsin
発行日: 2002年 8月
出版者: The Biophysical Society
誌名: Biophysical Journal
巻: 83
号: 2
開始ページ: 1130
終了ページ: 1135
抄録: Pharaonis phoborhodopsin (ppR; also pharaonis sensory rhodopsin II, psRII) is a receptor of the negative phototaxis of Natronobacterium pharaonis. By spectroscopic titration of D193N and D193E mutants, the pKa of the Schiff base was evaluated. Asp193 corresponds to Glu204 of bacteriorhodopsin (bR). The pKa of the Schiff base (SBH+) of D193N was ~10.1-10.0 (at XH+) and ~11.4-11.6 (at X) depending on the protonation state of a certain residue (designated by X) and independent of Cl, whereas those of the wild type and D193E were >12. The pKa values of XH+ were ~11.8-11.2 at the state of SB, 10.5 at SBH+ state in the presence of Cl, and 9.6 at SBH+ without Cl. These imply the presence of a long-range interaction in the extracellular channel. Asp193 was suggested to be deprotonated in the present dodecyl-maltoside (DDM) solubilized wild-type ppR, which is contrary to Glu204 of bR. In the absence of salts, the irreversible denaturation of D193N (but not the wild type and D193E) occurred via a metastable state, into which the addition of Cl reversed the intact pigment. This suggests that the negative charge at residue 193, which can be substituted by Cl, is necessary to maintain the proper conformation in the DDM-solubilized ppR.
資料タイプ: article (author version)
出現コレクション:雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

提供者: 加茂 直樹


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