Cryo-EM structure of a monomeric RC-LH1-PufX supercomplex with high-carotenoid content from Rhodobacter capsulatus
Cryo-EM structure of a monomeric RC-LH1-PufX supercomplex with high-carotenoid content from Rhodobacter capsulatus
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DOI：
10.1016/j.str.2023.01.006
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发表时间：
2023-03-02
期刊：
影响因子：
5.7
通讯作者：
Liu, Lu-Ning
中科院分区：
文献类型：
--
作者：
Bracun, Laura;Yamagata, Atsushi;Liu, Lu-Ning
在紫色光合作用细菌中，光化学反应中心(RC)和捕光复合体1(LH1)聚集在一起形成单体或二聚体RC-LH1膜复合体，这是细菌光合成所必需的。在这里，我们报告了2.59A分辨率的冷冻电子显微镜(CRYO-EM)结构的RC-LH1超复合体从红细菌胶囊。我们向澳大利亚央行展示。胶囊RC-LH1复合体是唯一的单体，其中RC被一个15个亚单位的LH1环包围。跨膜多肽PufX的掺入导致LH1环内的一个大开口。每个LH1亚基关联两个类胡萝卜素和两个细菌叶绿素，这类似于RBA。球藻RC-LH1，但在澳大利亚，每个LH1不止一个类胡萝卜素。Verdkampii RC-LH1单体。总而言之，唯一的澳大利亚央行。囊膜RC-LH1-PufX代表了一种介于RBA之间的中间结构。斯帕罗里德和澳洲央行。Veldkampii RC-LH1-PufX。比较三种红杆菌的PufX表明了参与RC-LH1二聚的重要残基。
In purple photosynthetic bacteria, the photochemical reaction center (RC) and light-harvesting complex 1 (LH1) assemble to form monomeric or dimeric RC-LH1 membrane complexes, essential for bacterial photo-synthesis. Here, we report a 2.59-A resolution cryoelectron microscopy (cryo-EM) structure of the RC-LH1 supercomplex from Rhodobacter capsulatus. We show that Rba. capsulatus RC-LH1 complexes are exclu-sively monomers in which the RC is surrounded by a 15-subunit LH1 ring. Incorporation of a transmembrane polypeptide PufX leads to a large opening within the LH1 ring. Each LH1 subunit associates two carotenoids and two bacteriochlorophylls, which is similar to Rba. sphaeroides RC-LH1 but more than one carotenoid per LH1 in Rba. veldkampii RC-LH1 monomer. Collectively, the unique Rba. capsulatus RC-LH1-PufX represents an intermediate structure between Rba. sphaeroides and Rba. veldkampii RC-LH1-PufX. Comparison of PufX from the three Rhodobacter species indicates the important residues involved in dimerization of RC-LH1.