Macromolecular crowding can account for RNase-sensitive constraint of bacterial nucleoid structure
Macromolecular crowding can account for RNase-sensitive constraint of bacterial nucleoid structure
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DOI：
10.1016/j.bbrc.2010.03.128
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发表时间：
2010-04-23
影响因子：
3.1
通讯作者：
Shuler, Michael L.
中科院分区：
文献类型：
--
作者：
Foley, Patricia L.;Wilson, David B.;Shuler, Michael L.
细菌类核的形状和压实可能影响遗传物质在自然和合成系统中的转录机制的可及性。为了研究这一现象，利用荧光和透射电子显微镜研究了从大肠杆菌细胞中轻轻释放的类核的性质和RNA和蛋白质对类核压实的贡献。我们提出，从细菌类核中去除RNA会通过改变类核的分支密度和分子量来影响类核的压实。我们表明，一种常见的洗涤剂在类核制剂，brij58，起着一个以前未被认识到的大分子拥挤剂的作用。当brij58浓度增加时，无rna的类核呈与指数相类核相似的致密结构，与我们的假设一致。我们提出的证据表明，对照和无蛋白类核在含有大分子拥挤剂的溶液中表现相似。这些结果表明，与大分子拥挤效应相比，核相关蛋白对DNA压实的贡献很小。(C) 2010爱思唯尔公司版权所有。
The shape and compaction of the bacterial nucleoid may affect the accessibility of genetic material to the transcriptional machinery in natural and synthetic systems. To investigate this phenomenon, the nature and contribution of RNA and protein to the compaction of nucleoids that had been gently released from Escherichia coli cells were investigated using fluorescent and transmission electron microscopy. We propose that the removal of RNA from the bacterial nucleoid affects nucleoid compaction by altering the branching density and molecular weight of the nucleoid. We show that a common detergent in nucleoid preparations, Brij 58, plays a previously unrecognized role as a macromolecular crowding agent. RNA-free nucleoids adopt a compact structure similar in size to exponential-phase nucleoids when the concentration of Brij 58 is increased, consistent with our hypothesis. We present evidence that control and protein-free nucleoids behave similarly in solutions containing a macromolecular crowding agent. These results show that the contribution to DNA compaction by nucleoid-associated proteins is small when compared to macromolecular crowding effects. (C) 2010 Elsevier Inc. All rights reserved.