The arrangement of proteins into complexes is a key organizational principle for many cellular functions. Although the topology of many complexes has been systematically analyzed in isolation, their molecular sociology in situ remains elusive. Here, we show that crude cellular extracts of a eukaryotic thermophile, Chaetomium thermophilum, retain basic principles of cellular organization. Using a structural proteomics approach, we simultaneously characterized the abundance, interactions, and structure of a third of the C. thermophilum proteome within these extracts. We identified 27 distinct protein communities that include 108 interconnected complexes, which dynamically associate with each other and functionally benefit from being in close proximity in the cell. Furthermore, we investigated the structure of fatty acid synthase within these extracts by cryoEM and this revealed multiple, flexible states of the enzyme in adaptation to its association with other complexes, thus exemplifying the need for in situ studies. As the components of the captured protein communities are known-at both the protein and complex levels-this study constitutes another step forward toward a molecular understanding of subcellular organization.

中文翻译：

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通过结构蛋白质组学在嗜热真核生物中捕获蛋白质群落。

将蛋白质排列成复合物是许多细胞功能的关键组织原则。尽管许多复合物的拓扑结构已经被孤立地系统地分析过，但它们的原位分子社会学仍然难以捉摸。在这里，我们展示了真核嗜热菌 Chaetomium thermophilum 的粗细胞提取物保留了细胞组织的基本原理。使用结构蛋白质组学方法，我们同时表征了这些提取物中三分之一嗜热梭菌蛋白质组的丰度、相互作用和结构。我们确定了 27 个不同的蛋白质群落，其中包括 108 个相互连接的复合物，它们动态地相互关联，并且在功能上受益于在细胞中的紧密接近。此外，我们通过 cryoEM 研究了这些提取物中脂肪酸合酶的结构，这揭示了酶的多种灵活状态以适应其与其他复合物的结合，从而证明了原位研究的必要性。由于捕获的蛋白质群落的成分在蛋白质和复合物水平上都是已知的，这项研究构成了朝着亚细胞组织的分子理解迈出的又一步。