Enterococcus hiraeからのV-ATPaseのK環のナトリウムまたはリチウムイオン結合誘発構造の変化は,ATR-FTIRスペクトロスコピーによって明らかになりました

Yuji Furutani¹, Takeshi Murata, Hideki Kandori

¹Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.

Journal of the American Chemical Society

|February 16, 2011

まとめ

V-ATPase酵素は,ナトリウムとリチウムイオンを輸送する. イオン結合は,Glu139のデプロトネーションのような重要な構造変化を引き起こし,膜を横断する効率的なカチオン輸送を促進します.

科学分野:

バイオケミストリーバイオケミストリー
構造生物学構造生物学とは
メンブレーン輸送メンブレーン輸送

背景:

Enterococcus hiraeからのV-ATPaseは,大規模なタンパク質複合体 (∼700,000 MW) である.
それは生理的に,脂質二重層にNa(+) とLi(+) を輸送する.
以前の研究は,膜に埋め込まれたK環領域のX線結晶学に依存していた.

研究の目的:

生理学的条件下で,不変のV-ATPaseのイオン結合誘発構造変化を調査する.
カチオン輸送における特定の残留物と形状の変化の役割を明らかにする.

主な方法:

健全なV-ATPaseの赤外線 (IR) スペクトルのイオン結合誘発差異の測定.
実験は,十分な水分補給を伴う生理学的温度で実施した.

主要な成果:

ナトリウムまたはリチウムイオン結合は,Glu139.9のデプロトネーションを誘導する.
タイロシン残留物の水素結合の変化を観察した.
K環構造内の軽微な形状の変化が検出されました.

結論:

Glu139のデプロトネーションは,カチオン輸送に不可欠です.
構造の変化は,イオン転移のためのエネルギー障壁の減少を促進します.
これらの発見は,V-ATPaseによるカチオン輸送のメカニズムについての洞察を提供します.

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