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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Forces guiding assembly of light-harvesting complex 2 in native membranes
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Forces guiding assembly of light-harvesting complex 2 in native membranes

机译：强制引导集光复合物2在天然膜中的组装

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摘要

Interaction forces of membrane protein subunits are of importance in their structure, assembly, membrane insertion, and function. In biological membranes, and in the photosynthetic apparatus as a paradigm, membrane proteins fulfill their function by ensemble actions integrating a tight assembly of several proteins. In the bacterial photosynthetic apparatus light-harvesting complexes 2 (LH2) transfer light energy to neighboring tightly associated core complexes, constituted of light-harvesting complexes 1 (LH1) and reaction centers (RC). While the architecture of the photosynthetic unit has been described, the forces and energies assuring the structural and functional integrity of LH2, the assembly of LH2 complexes, and how LH2 interact with the other proteins in the supra-molecular architecture are still unknown. Here we investigate the molecular forces of the bacterial LH2 within the native photosynthetic membrane using atomic force microscopy single-molecule imaging and force measurement in combination. The binding between LH2 subunits is fairly weak, of the order of k_BT, indicating the importance of LH2 ring architecture. In contrast LH2 subunits are solid with a free energy difference of 90 k_BT between folded and unfolded states. Subunit α-helices unfold either in one-step, a- and p-polypeptides unfold together, or sequentially. The unfolding force of transmembrane helices is approximately 150 pN. In the two-step unfolding process, the p-polypeptide is stabilized by the molecular environment in the membrane. Hence, intermolecular forces influence the structural and functional integrity of LH2.
机译：膜蛋白亚基的相互作用力在其结构，组装，膜插入和功能中很重要。在生物膜中，以及在作为光合作用的范例中，膜蛋白通过整合多种蛋白紧密结合的整体作用来实现其功能。在细菌的光合作用设备中，光收集复合体2（LH2）将光能转移到由光收集复合体1（LH1）和反应中心（RC）组成的相邻紧密相关的核心复合体中。虽然已经描述了光合作用单元的结构，但仍不清楚如何确保LH2的结构和功能完整性，LH2复合物的组装以及LH2如何与超分子结构中的其他蛋白质相互作用的作用力和能量。在这里，我们使用原子力显微镜单分子成像和力测量相结合的方法研究天然光合膜内细菌LH2的分子力。 LH2亚基之间的结合相当弱，约为k_BT，表明LH2环结构的重要性。相反，LH2亚基是固体，在折叠和未折叠状态之间的自由能差为90 k_BT。亚基α-螺旋可一步展开，α-和p-多肽一起展开或顺序展开。跨膜螺旋的展开力约为150 pN。在两步展开过程中，对-多肽被膜中的分子环境所稳定。因此，分子间作用力影响LH2的结构和功能完整性。

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    Lu-Ning Liu; Katia Duquesne; Filipp Oesterhelt; James N. Sturgis; Simon Scheuring;

  • 作者单位

    Institut Curie, U1006 Institut National de la Sante et Recherche Medicale, Paris, F-75248 France;

    Unite Propre de Recherche-9027 Laboratoire d'lngenierie des Systemes Macromoleculaires, Centre National de la Recherche Scientifique-Aix-Marseille University, Marseille, 13402, France;

    Heinrich-Heine-Universitat, Institut fur Molekulare Physikalische Chemie, Dusseldorf, D-40225, Germany;

    Unite Propre de Recherche-9027 Laboratoire d'lngenierie des Systemes Macromoleculaires, Centre National de la Recherche Scientifique-Aix-Marseille University, Marseille, 13402, France;

    Institut Curie, U1006 Institut National de la Sante et Recherche Medicale, Paris, F-75248 France;

  • 收录信息 美国《科学引文索引》(SCI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    atomic force microscopy; photosynthesis; protein unfolding; membrane protein assembly;

    机译：原子力显微镜光合作用;蛋白质展开膜蛋白组装;

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