Direct characterization of the native structure and mechanics of cyanobacterial carboxysomes.
Direct characterization of the native structure and mechanics of cyanobacterial carboxysomes.
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DOI：
10.1039/c7nr02524f
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发表时间：
2017-08-03
期刊：
影响因子：
6.7
通讯作者：
Liu LN
中科院分区：
文献类型：
--
作者：
Faulkner M;Rodriguez-Ramos J;Dykes GF;Owen SV;Casella S;Simpson DM;Beynon RJ;Liu LN
对蓝藻中自组装的固碳机制--天然羧基体的蛋白质空间结构、拓扑结构和物理机制进行了研究。碳酶体是一类蛋白质细胞器，在蓝藻和某些变形菌的固碳过程中起着重要作用。这些自组装的细胞器使用结构上类似于二十面体病毒衣壳的蛋白质外壳封装核酮糖1，5-二磷酸羧化酶/加氧酶（Rubisco）和碳酸酐酶。蛋白质壳作为物理屏障以保护酶免受胞质溶胶的影响，并作为选择性渗透膜以介导酶底物和产物的转运。天然羧基体的结构和机械性质仍不清楚。在这里，我们从蓝细菌细长聚球藻PCC 7942中分离功能性β-羧基体，并使用电子显微镜、原子力显微镜（AFM）和蛋白质组学对单个β-羧基体的大分子结构和固有物理力学进行首次表征。结果表明，完整的β-羧基体由三个结构域组成：单层二十面体壳、内层和内部Rubisco的准晶排列。我们还观察到壳和部分β-羧基体的蛋白质组织，它们可能是β-羧基体组装的中间体。此外，在天然条件下使用AFM和基于AFM的纳米压痕确定功能性β-羧基体的形貌和内在力学，揭示了与刚性病毒相比β-羧基体的柔性组织和软机械性质。我们的研究为β-羧基体组织和纳米力学的自然特征提供了新的见解，这些特征可以扩展到不同的细菌微区室，并且是其他生物体中功能性羧基体的设计和工程化以增压光合作用的重要考虑因素。它提供了一种方法来检查合成代谢细胞器和蛋白质支架在生物工程中的结构和力学特性。
The spatial protein organization, topography and physical mechanics of native carboxysomes, the self-assembling carbon-fixation machinery in cyanobacteria, were characterized. Carboxysomes are proteinaceous organelles that play essential roles in enhancing carbon fixation in cyanobacteria and some proteobacteria. These self-assembling organelles encapsulate Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) and carbonic anhydrase using a protein shell structurally resembling an icosahedral viral capsid. The protein shell serves as a physical barrier to protect enzymes from the cytosol and a selectively permeable membrane to mediate transport of enzyme substrates and products. The structural and mechanical nature of native carboxysomes remain unclear. Here, we isolate functional β-carboxysomes from the cyanobacterium Synechococcus elongatus PCC7942 and perform the first characterization of the macromolecular architecture and inherent physical mechanics of single β-carboxysomes using electron microscopy, atomic force microscopy (AFM) and proteomics. Our results illustrate that the intact β-carboxysome comprises three structural domains, a single-layered icosahedral shell, an inner layer and paracrystalline arrays of interior Rubisco. We also observe the protein organization of the shell and partial β-carboxysomes that likely serve as the β-carboxysome assembly intermediates. Furthermore, the topography and intrinsic mechanics of functional β-carboxysomes are determined in native conditions using AFM and AFM-based nanoindentation, revealing the flexible organization and soft mechanical properties of β-carboxysomes compared to rigid viruses. Our study provides new insights into the natural characteristics of β-carboxysome organization and nanomechanics, which can be extended to diverse bacterial microcompartments and are important considerations for the design and engineering of functional carboxysomes in other organisms to supercharge photosynthesis. It offers an approach for inspecting the structural and mechanical features of synthetic metabolic organelles and protein scaffolds in bioengineering.
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影响因子：
56.9
作者：
Behrenfeld, MJ;Randerson, JT;Pollack, NH
通讯作者：
Pollack, NH
影响因子：
3.7
作者：
Arteni, Ana A.;Liu, Lu-Ning;Aartsma, Thijs J.;Zhang, Yu-Zhong;Zhou, Bai-Cheng;Boekema, Egbert J.
通讯作者：
Boekema, Egbert J.
影响因子：
7.4
作者：
Cai, Fei;Bernstein, Susan L.;Kerfeld, Cheryl A.
通讯作者：
Kerfeld, Cheryl A.
影响因子：
3.2
作者：
Baker, SH;Jin, SM;Shively, JM
通讯作者：
Shively, JM
影响因子：
56.9
作者：
Kerfeld, CA;Sawaya, MR;Yeates, TO
通讯作者：
Yeates, TO