Orientations of Iron-Sulfur Clusters FA and FB in the Homodimeric Type-I Photosynthetic Reaction Center of Heliobacterium modesticaldum
Orientations of Iron-Sulfur Clusters FA and FB in the Homodimeric Type-I Photosynthetic Reaction Center of Heliobacterium modesticaldum
复制标题
谦虚杆菌同二聚体I型光合反应中心铁硫簇FA和FB的取向
DOI：
10.1021/acs.jpcb.6b01112
复制
发表时间：
2016
期刊：
影响因子：
--
通讯作者：
H. Oh-oka
中科院分区：
文献类型：
--
作者：
T. Kondo;M. Matsuoka;C. Azai;S. Itoh;H. Oh-oka
用电子顺磁共振(EPR)研究了结构未知的I型同源二聚体疱疹杆菌I型反应中心(HRC)中FA型和FB型铁硫(FeS)簇在嗜热厌氧光合细菌膜中的取向，并与异二聚体光系统I(PS I)中的取向进行了比较。细胞色素b/c复合体中的Rieske型FeS中心显示良好的EPR信号。14K光照诱导出g轴分别为gz=2.066、gy=1.937和gx=1.890的FB信号，分别与膜的正常方向成60°、60°和45°倾斜。二亚硫酸盐的化学还原产生了一个额外的FA-信号，该信号在30°、60°和90°时分别与Fb-发生磁相互作用，gz=2.046，gy=1.942，gx=1.911。HRC中FA-和FB-的角度和氧化还原性质分别与PS I中的FB-和FA-相似。因此，在PS I中，以其g值相似性命名的FA和FBin HRC似乎分别位于FBB和FA，而不是FAB和FB。如果FA和FB2的名字互换，HRC的还原边可能与PS I中的相似。
Orientations of the FAand FBiron–sulfur (FeS) clusters in a structure-unknown type-I homodimeric heriobacterial reaction center (hRC) were studied in oriented membranes of the thermophilic anaerobic photosynthetic bacteriumHeliobacterium modesticaldumby electron paramagnetic resonance (EPR), and compared with those in heterodimeric photosystem I (PS I). The Rieske-type FeS center in the cytochromeb/ccomplex showed a well-oriented EPR signal. Illumination at 14 K induced an FB–signal withg-axes ofgz= 2.066,gy= 1.937, andgx= 1.890, tilted at angles of 60°, 60°, and 45°, respectively, with respect to the membrane normal. Chemical reduction with dithionite produced an additional signal of FA–, which magnetically interacted with FB–, withgz= 2.046,gy= 1.942, andgx= 1.911 at 30°, 60°, and 90°, respectively. The angles and redox properties of FA–and FB–in hRC resemble those of FB–and FA–, respectively, in PS I. Therefore, FAand FBin hRC, named after theirg-value similarities, seem to be located like FBand FA, not like FAand FB, respectively, in PS I. The reducing side of hRC could resemble those in PS I, if the names of FAand FBare interchanged with each other.