A Study of the Dynamics of the Heme Pocket and C-helix in CooA Upon CO Dissociation Using Time-resolved Visible and UV Resonance Raman Spectroscopy
A Study of the Dynamics of the Heme Pocket and C-helix in CooA Upon CO Dissociation Using Time-resolved Visible and UV Resonance Raman Spectroscopy
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使用时间分辨可见光和紫外共振拉曼光谱研究 CO 解离时 CooA 中血红素袋和 C 螺旋的动力学
DOI：
10.1021/acs.jpcb.6b05634
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发表时间：
2016
期刊：
影响因子：
3.3
通讯作者：
and Yasuhisa Mizutani
中科院分区：
文献类型：
--
作者：
Akihiro Otomo;Haruto Ishikawa;Misao Mizuno;Tetsunari Kimura;Minoru Kubo;Yoshitsugu Shiro;Shigetoshi Aono;and Yasuhisa Mizutani
CooA是一种CO传感转录激活剂，来自光合细菌红红螺旋菌，它在血红素铁上结合CO。CooA亚铁中的血红素铁有两个轴向配体：His77和Pro2。CO取代Pro2，引起CooA的构象变化。CO的解离和/或Pro2残基的连接被认为会触发蛋白质的结构变化。本研究获得的可见光时间分辨共振拉曼光谱表明，在CO光解50 μs后，由his77 -铁近端拉伸产生的ν(Fe-His)模式才发生位移。在CO光解50 μs左右，观察到Pro2残基与血红素铁的结合，表明ν(Fe-His)波段直到Pro2结合后才发生位移。紫外共振拉曼光谱显示CO结合后c -螺旋Trp110附近的结构发生了变化，但CO光解后100 ~ 100 μs的时间分辨紫外共振拉曼光谱没有或非常小的变化，这些结果强烈表明Pro2与血红素铁的连接引起了CooA的构象变化。
CooA is a CO-sensing transcriptional activator from the photosynthetic bacteriumRhodospirillum rubrumthat binds CO at the heme iron. The heme iron in ferrous CooA has two axial ligands: His77 and Pro2. CO displaces Pro2 and induces a conformational change in CooA. The dissociation of CO and/or ligation of the Pro2 residue are believed to trigger structural changes in the protein. Visible time-resolved resonance Raman spectra obtained in this study indicated that the ν(Fe–His) mode, arising from the proximal His77–iron stretch, does not shift until 50 μs after the photodissociation of CO. Ligation of the Pro2 residue to the heme iron was observed around 50 μs after the photodissociation of CO, suggesting that the ν(Fe–His) band exhibits no shift until the ligation of Pro2. UV resonance Raman spectra suggested structural changes in the vicinity of Trp110 in the C-helix upon CO binding, but no or very small spectral changes in the time-resolved UV resonance Raman spectra were observed from 100 ns to 100 μs after the photodissociation of CO. These results strongly suggest that the conformational change of CooA is induced by the ligation of Pro2 to the heme iron.