Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK.
Nat Commun. 2013;4:3003. doi: 10.1038/ncomms3003.
In bacteria, chromosomal architecture shows strong spatial and temporal organization, and regulates key cellular functions, such as transcription. Tracking the motion of chromosomal loci at short timescales provides information related to both the physical state of the nucleo-protein complex and its local environment, independent of large-scale motions related to genome segregation. Here we investigate the short-time (0.1-10 s) dynamics of fluorescently labelled chromosomal loci in Escherichia coli at different growth rates. At these timescales, we observe for the first time a dependence of the loci's apparent diffusion on both their subcellular localization and chromosomal coordinate, and we provide evidence that the properties of the chromosome are similar in the tested growth conditions. Our results indicate that either non-equilibrium fluctuations due to enzyme activity or the organization of the genome as a polymer-protein complex vary as a function of the distance from the origin of replication.
在细菌中，染色体结构表现出强烈的时空组织，调节着关键的细胞功能，如转录。在短时间尺度上跟踪染色体位置的运动提供了与核蛋白复合物的物理状态及其局部环境相关的信息，而与与基因组分离相关的大规模运动无关。在这里，我们研究了不同生长速率下大肠杆菌中荧光标记染色体位置的短时间（0.1-10s）动力学。在这些时间尺度上，我们首次观察到，染色体位置的表观扩散依赖于其亚细胞定位和染色体坐标，并且我们提供了证据表明，在测试的生长条件下，染色体的性质是相似的。我们的结果表明，要么是由于酶活性引起的非平衡波动，要么是基因组作为聚合物-蛋白质复合物的组织，随着与复制原点的距离而变化。
