Localization of cyanobacterial photosystem II donor-side subunits by electron microscopy and the supramolecular organization of photosystem II in the thylakoid membrane
Localization of cyanobacterial photosystem II donor-side subunits by electron microscopy and the supramolecular organization of photosystem II in the thylakoid membrane
复制标题
通过电子显微镜对蓝藻光系统II供体侧亚基的定位以及类囊体膜中光系统II的超分子结构
DOI：
10.1046/j.1432-1327.1999.00877.x
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发表时间：
1999-12-01
期刊：
影响因子：
--
通讯作者：
Boekema, EJ
中科院分区：
文献类型：
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作者：
Kuhl, H;Rögner, M;Boekema, EJ
用单粒子图像分析方法对从长聚球藻中分离到的光系统II(PSII)二聚体的大量电子显微镜投影进行了表征。除了以前发布的较低分辨率的地图[Boekema，E.J.，Hankamer，B.，Bald，D.，Kruip，J.，Neld，J.，Boonstra，A.F.，Barber，J.&Rogner，M.(1995)Proc.纳特·阿卡德。SCI。美国92,175-179]，新的侧视投影显示了所有三个管腔外源蛋白的密度，即分别由psbO、psbU和psbV编码的33-kDa、12-kDa和细胞色素c-550亚基。对俯视投影的大小和形状的分析揭示了少量的光系统II粒子，其大小大约是通常二聚体的两倍。这些“双二聚体”的大小和数量与高效液相色谱尺寸排除分析中发现的一小部分1000 kDa颗粒相关。由于许多蓝藻含有在膜内成排排列的二聚体光系统II复合体，因此双二聚体可以被认为是这些行的分解片段。他们的分析使得能够检测到光系统II在行内的排列，其中二聚体主要通过它们的尖端与其他二聚体相互作用，在两个二聚体的交界处留下了一个相当开放的中心。二聚体的重复距离仅为11.7 nm。因此，位于PSII的LOP上的藻胆体必须紧密堆积在一起或几乎相互接触，这种方式类似于最近提出的模型[Bald，D.，Kruip，J.&Rogner，M.(1996)光合作用研究49,103-118]。
A large set of electron microscopy projections of photosystem II (PSII) dimers isolated from the cyanobacterium Synechococcus elongatus was characterized by single particle image analysis. In addition to previously published maps at lower resolution [Boekema, E.J., Hankamer, B., Bald, D., Kruip, J., Nield, J., Boonstra, A.F., Barber, J. & Rogner, M. (1995) Proc. Natl Acad. Sci. USA 92, 175-179], the new side-view projections show densities of all three lumenal extrinsic proteins, i.e. the 33-kDa, 12-kDa and the cytochrome c-550 subunit encoded by psbO, psbU and psbV, respectively. Analysis of the size and shape of the top-view projections revealed a small number of photosystem II particles of about double the size of the usual dimers. Size and quantity of these 'double dimers' correlates with a small fraction of 1000-kDa particles found with HPLC-size-exclusion chromatographic analysis. Because many cyanobacteria contain dimeric photosystem II complexes arranged in rows within the membrane, the double dimers can be considered as the breakdown fragments of these rows. Their analysis enabled the detection of the arrangement of photosystem II within the rows, in which the dimers interact with other dimers mostly with their tips, leaving a rather open center at the interfaces of two dimers. The dimers have a repeating distance of only 11.7 nm. As a consequence, the phycobilisomes, located on Lop of PSII and functioning in light-harvesting, must be closely packed or almost touch each other, in a manner similar to a recently suggested model [Bald, D., Kruip, J. & Rogner, M.(1996) Photosynthesis Res. 49, 103-118].