Compaction and self-association of megabase-sized chromatin are induced by anionic protein crowding.
Compaction and self-association of megabase-sized chromatin are induced by anionic protein crowding.
复制标题
阴离子蛋白质拥挤诱导兆碱基大小染色质的压缩和自缔合。
作者：
A. Zinchenko;Qinming Chen;N. Berezhnoy;Sai Wang;L. Nordenskiöld
高度致密的染色质是DNA与阳离子组蛋白的复合物，存在于高浓度大分子物质环境中的真核细胞核中，其中许多大分子物质具有负电荷。然而，在以前的大多数研究中，这些拥挤条件是使用中性合成大分子如聚乙二醇（PEG）进行实验建模的。尽管拥挤剂电荷在染色质的缩合过程中的重要性，据我们所知，染色质在阴离子蛋白质拥挤条件下的行为尚未研究。在这里，压实近兆碱基长的染色质在阴离子球状蛋白BSA的存在下，通过单分子荧光显微镜（FM）进行了研究。我们证明了不同的影响，阴离子大分子拥挤（MMCs）的DNA和染色质相比，中性MMCs。而DNA分子在钙存在下逐渐压缩成球状。20%w/v的BSA，染色质纤维在低得多的BSA浓度下完成卷曲至球状体的转变（约20% w/v）。5%w/v）。此外，在溶液中较高浓度的BSA（> 5%w/v）下，染色质纤维自缔合并形成大的球形或纤维状超分子微结构，其特征在于高胶体稳定性和动态分子间波动。从染色质形成这种自组织胶体是普遍的，并且是各种长度的染色质纤维的特征。我们的研究结果突出了迄今未被充分认识的影响，阴离子MMC环境染色质的高阶结构，可能发挥重要作用，在体内的自组织染色质。
Highly compacted chromatin, a complex of DNA with cationic histone proteins, is found in the nucleus of eukaryotic cells in an environment with a high concentration of macromolecular species, many of which possess a negative charge. In the majority of previous studies, however, these crowding conditions were experimentally modelled using neutral synthetic macromolecules such as polyethylene glycol (PEG). Despite the importance of the crowding agent charge in the condensation process of chromatin, to the best of our knowledge, the behavior of chromatin under conditions of anionic protein crowding has not been studied. Here, compaction of nearly megabase-long chromatin in the presence of the anionic globular protein BSA was investigated by single-molecule fluorescent microscopy (FM). We demonstrate different effects of anionic macromolecular crowders (MMCs) on DNA and chromatin, compared to neutral MMCs. While DNA molecules undergo gradual compaction into a globular form in the presence of ca. 20% w/v of BSA, chromatin fibres complete coil to globule transition at a much lower concentration of BSA (ca. 5% w/v). Furthermore, at higher concentrations of BSA in solution (>5% w/v), chromatin fibres self-associate and form large spherical or fibrillar supramolecular microstructures characterized by a high colloidal stability and dynamic intermolecular fluctuations. Formation of such self-organized colloids from chromatin is universal and characteristic of chromatin fibres of various lengths. Our results highlight the hitherto underappreciated effect of anionic MMC environment on chromatin higher-order structures that may play an important role in self-organization of chromatin in vivo.
影响因子：
3.4
作者：
Armstrong, JK;Wenby, RB;Fisher, TC
通讯作者：
Fisher, TC