Laboratory of Physical Chemistry and Colloid Science, Wageningen University, P.O. Box 8038, 6700 EK Wageningen, the Netherlands.
Biochimie. 2010 Dec;92(12):1715-21. doi: 10.1016/j.biochi.2010.06.024. Epub 2010 Jul 6.
The volume of a typical Eschericia coli nucleoid is roughly 10(4) times smaller than the volume of a freely coiling linear DNA molecule with the same length as the E. coli genome. We review the main forces that have been suggested to contribute to this compaction factor: macromolecular crowding (that "pushes" the DNA together), DNA charge neutralization by various polycationic species (that "glues" the DNA together), and finally, DNA deformations due to DNA supercoiling and nucleoid proteins. The direct contributions of DNA supercoiling and nucleoid proteins to the total compaction factor are probably small. Instead, we argue that the formation of the bacterial nucleoid can be described as a consequence of the influence of macromolecular crowding on thick, supercoiled protein-DNA fibers, that have been partly charge neutralized by small multivalent cations.
大肠杆菌拟核的体积大约是与其基因组长度相同的自由卷曲线性 DNA 分子体积的 10^4 倍。我们综述了可能促成这种压缩因子的主要力：大分子拥挤（将 DNA 挤在一起）、各种聚阳离子物质的 DNA 电荷中和（将 DNA 粘在一起），以及最后，由于 DNA 超螺旋和核基质蛋白导致的 DNA 变形。DNA 超螺旋和核基质蛋白对总压缩因子的直接贡献可能很小。相反，我们认为细菌拟核的形成可以描述为大分子拥挤对部分电荷中和的厚、超螺旋蛋白-DNA 纤维的影响的结果，这些纤维已被小多价阳离子部分中和。
