Lim Ci Ji, Kenney Linda J, Yan Jie
Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore Centre for Bioimaging Sciences, National University of Singapore, Singapore Mechanobiology Institute, Singapore Department of Physics, National University of Singapore, Singapore.
Mechanobiology Institute, Singapore Jesse Brown Veterans Affairs Medical Center, Chicago, IL, USA Department of Microbiology & Immunology, University of Illinois-Chicago, Chicago, IL, USA Department of Biological Sciences, National University of Singapore, Singapore.
Nucleic Acids Res. 2014 Jul;42(13):8369-78. doi: 10.1093/nar/gku566. Epub 2014 Jul 2.
The Escherichia coli H-NS protein is a major nucleoid-associated protein that is involved in chromosomal DNA packaging and gene regulatory functions. These biological processes are intimately related to the DNA supercoiling state and thus suggest a direct relationship between H-NS binding and DNA supercoiling. Here, we show that H-NS, which has two distinct DNA-binding modes, is able to differentially regulate DNA supercoiling. H-NS DNA-stiffening mode caused by nucleoprotein filament formation is able to suppress DNA plectoneme formation during DNA supercoiling. In contrast, when H-NS is in its DNA-bridging mode, it is able to promote DNA plectoneme formation during DNA supercoiling. In addition, the DNA-bridging mode is able to block twists diffusion thus trapping DNA in supercoiled domains. Overall, this work reveals the mechanical interplay between H-NS and DNA supercoiling which provides insights to H-NS organization of chromosomal DNA based on its two distinct DNA architectural properties.
大肠杆菌H-NS蛋白是一种主要的类核相关蛋白，参与染色体DNA包装和基因调控功能。这些生物学过程与DNA超螺旋状态密切相关，因此表明H-NS结合与DNA超螺旋之间存在直接关系。在这里，我们表明具有两种不同DNA结合模式的H-NS能够差异调节DNA超螺旋。由核蛋白丝形成引起的H-NS DNA硬化模式能够在DNA超螺旋过程中抑制DNA麻花状结构的形成。相反，当H-NS处于其DNA桥接模式时，它能够在DNA超螺旋过程中促进DNA麻花状结构的形成。此外，DNA桥接模式能够阻止扭曲扩散，从而将DNA捕获在超螺旋结构域中。总体而言，这项工作揭示了H-NS与DNA超螺旋之间的机械相互作用，这为基于其两种不同DNA结构特性的H-NS对染色体DNA的组织提供了见解。
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