Supramolecular Hemoprotein Assembly with a Periodic Structure Showing Heme-Heme Exciton Coupling
Supramolecular Hemoprotein Assembly with a Periodic Structure Showing Heme-Heme Exciton Coupling
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DOI：
10.1021/jacs.8b06690
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发表时间：
2018-08-15
影响因子：
15
通讯作者：
Hayashi, Takashi
中科院分区：
文献类型：
--
作者：
Oohora, Koji;Fujimaki, Nishiki;Hayashi, Takashi
研究了细胞色素B（562）单元与外部连接的血红素的超分子组装，所述血红素具有通过血红素-血红素口袋相互作用形成的分子间键，以努力构建定义明确的结构。在细胞色素12，62的N80 C突变体中，用于血红素在Cys 80处的表面附着的工程化位点提供了形成周期性组装结构的主要基础，其在本文中通过圆二色性（CD）光谱和高速原子力显微镜（AFM）表征。该组装代表了在人工血红素蛋白组装系统中通过血红素血红素激子耦合观察分裂型棉花效应的第一个例子。通过模拟CD光谱，AFM图像和突变实验验证的分子动力学模拟表明，该组装体具有3 nm间距的周期性螺旋结构，表明组装结构的形成不仅由血红素血红素口袋相互作用驱动，而且还由组装体的蛋白质界面处的额外二级氢键和/或静电相互作用驱动。
A supramolecular assembly of units of cytochrome b(562) with externally attached heme having intermolecular linkages formed via the heme-heme pocket interaction was investigated in an effort to construct a well-defined structure. The engineered site for surface attachment of heme at Cys80 in an N80C mutant of cytochrome 12,62 provides the primary basis for the formation of the periodic assembly structure, which is characterized herein by circular dichroism (CD) spectroscopy and high-speed atomic force microscopy (AFM). This assembly represents the first example of the observation of a split-type Cotton effect by heme heme exciton coupling in an artificial hemoprotein assembly system. Molecular dynamics simulations validated by simulated CD spectra, AFM images, and mutation experiments reveal that the assembly has a periodic helical structure with 3 nm pitches, suggesting the formation of the assembled structure is driven not only by the heme heme pocket interaction but also by additional secondary hydrogen bonding and/or electrostatic interactions at the protein interfaces of the assembly.