Monomeric RC-LH1 core complexes retard LH2 assembly and intracytoplasmic membrane formation in PufX-minus mutants of Rhodobacter sphaeroides
Monomeric RC-LH1 core complexes retard LH2 assembly and intracytoplasmic membrane formation in PufX-minus mutants of Rhodobacter sphaeroides
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DOI：
10.1016/j.bbabio.2011.05.019
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发表时间：
2011-09-01
影响因子：
4.3
通讯作者：
Hunter, C. Neil
中科院分区：
文献类型：
--
作者：
Adams, Peter G.;Mothersole, David J.;Hunter, C. Neil
在光合细菌Rhodobacter sphaeroides模型中，捕光2（LH 2）复合物的结构域围绕并互连二聚反应中心捕光1-PufX（RC-LH 1-PufX）“核心”复合物，形成广泛的能量传递和捕获网络。这些复合物被安置在球形胞质膜（ICM）中，这些胞质膜以逐步的过程组装，其中核心复合物的生物合成往往主导膜内陷的早期阶段。在组装单体核心复合物的PufX突变体中测量LH 2组装的动力学，这是Put（PufX Delta 12）的十二个残基N-末端截短或PufX（PufX（-））完全去除的结果。对于来自PufX（-）突变体的较大且弯曲较小的ICM，观察到LH 2组装速率较低且膜内陷成熟延迟，这与由弯曲的RC-LH 1-PufX二聚体阵列引发的局部膜弯曲为LH 2复合物的稳定组装创造有利环境的主张一致。透射电子显微镜和高分辨率原子力显微镜被用来检查ICM形态和膜蛋白组织在这些突变体。在PufX-膜中观察到核心和LH 2复合物的一些分配，导致单体RC-LH 1复合物的局部有序簇。核心和LH 2复合物在所检查的三种类型的膜中的分布与膜曲率和结构域形成的先前模型一致（Freese等人，2008），其表明膜蛋白复合物的大小和形状的拥挤和不对称的组合驱动膜组织。(C)2011 Elsevier B. V.保留所有权利。
In the model photosynthetic bacterium Rhodobacter sphaeroides domains of light-harvesting 2 (LH2) complexes surround and interconnect dimeric reaction centre-light-harvesting 1-PufX (RC-LH1-PufX) 'core' complexes, forming extensive networks for energy transfer and trapping. These complexes are housed in spherical intracytoplasmic membranes (ICMs), which are assembled in a stepwise process where biosynthesis of core complexes tends to dominate the early stages of membrane invagination. The kinetics of LH2 assembly were measured in PufX mutants that assemble monomeric core complexes, as a consequence of either a twelve-residue N-terminal truncation of Put)( (PufX Delta 12) or the complete removal of PufX (PufX(-)). Lower rates of LH2 assembly and retarded maturation of membrane invagination were observed for the larger and less curved ICM from the PufX(-) mutant, consistent with the proposition that local membrane curvature, initiated by arrays of bent RC-LH1-PufX dimers, creates a favourable environment for stable assembly of LH2 complexes. Transmission electron microscopy and high-resolution atomic force microscopy were used to examine ICM morphology and membrane protein organisation in these mutants. Some partitioning of core and LH2 complexes was observed in PufX- membranes, resulting in locally ordered clusters of monomeric RC-LH1 complexes. The distribution of core and LH2 complexes in the three types of membrane examined is consistent with previous models of membrane curvature and domain formation (Frese et al., 2008), which demonstrated that a combination of crowding and asymmetries in sizes and shapes of membrane protein complexes drives membrane organisation. (C) 2011 Elsevier B.V. All rights reserved.