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活细菌中观察拟核相关蛋白介导染色体组装（CNS翻译练习）
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活细菌中观察拟核相关蛋白介导染色体组装
细菌染色体被限制在亚微米大小的拟核中。拟核相关蛋白（NAP）易化染色体组装，但作用过程还不清楚。 在本文中，我们使用了超高分辨率荧光显微镜，并结合染色体构象捕获分析法研究了活大肠杆菌中主要NAP的分布。 四种NAP,HU, Fis, IHF, 以及 StpA在拟核中分布很分散 。 相反，H-NS，一个多功能转录沉默子，在每个染色体上形成两个紧密簇，由DNA结合H-NS寡聚化驱动。这是由它氨基末端结构域与DNA相互作用。 H-NS将这些操纵子隔离到这些簇之中，并与无数的染色体上广泛分布的DNA片段并列存在。 敲除H-NS导致严重的染色体重组装。
这些观察结果显示了H-NS在细菌全局染色体组装中扮演了重要角色。
Science. 2011 Sep 9;333(6048):1445-9.
Chromosome organization by a nucleoid-associated protein in live bacteria.
Wang W, Li GW, Chen C, Xie XS, Zhuang X.
Source
Department of Physics, Harvard University, Cambridge, MA 02138, USA.
Abstract
Bacterial chromosomes are confined in submicrometer-sized nucleoids. Chromosome organization is facilitated by nucleoid-associatedproteins (NAPs), but the mechanisms of action remain elusive. In this work, we used super-resolution fluorescence microscopy, in combination with a chromosome-conformation capture assay, to study the distributions of major NAPs in live Escherichia coli cells. Four NAPs--HU, Fis, IHF, and StpA--were largely scattered throughout the nucleoid. In contrast, H-NS, a global transcriptional silencer, formed two compact clusters per chromosome, driven by oligomerization of DNA-bound H-NS through interactions mediated by the amino-terminal domain of the protein. H-NS sequestered the regulated operons into these clusters and juxtaposed numerous DNA segments broadly distributed throughout the chromosome. Deleting H-NS led to substantial chromosome reorganization. These observations demonstrate that H-NS plays a key role in global chromosome organization in bacteria.
https://blog.sciencenet.cn/blog-464637-486933.html
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