Skoko Dunja, Yan Jie, Johnson Reid C, Marko John F
Department of Physics, University of Illinois at Chicago, 845 West Taylor Street, Chicago, Illinois 60607-7059, USA.
Phys Rev Lett. 2005 Nov 11;95(20):208101. doi: 10.1103/PhysRevLett.95.208101. Epub 2005 Nov 8.
We report single-DNA-stretching experiments showing that the protein Fis, an abundant bacterial chromosome protein of E. coli, mediates a dramatic DNA condensation to zero length. This condensation occurs abruptly when DNA tension is reduced below a protein-concentration-dependent threshold f* < 1 pN. Following condensation, reopening under larger forces proceeds via a series of discrete jumps, indicating that Fis is able to stabilize DNA crossings. Our experiments suggest that Fis may play a role in vivo stabilizing the "loop-domain" structure of the bacterial chromosome.
我们报告了单DNA拉伸实验，结果表明蛋白质Fis（一种大肠杆菌中丰富的细菌染色体蛋白）介导了DNA急剧浓缩至零长度。当DNA张力降低到低于蛋白质浓度依赖性阈值f*<1皮牛时，这种浓缩会突然发生。浓缩后，在更大的力作用下重新打开是通过一系列离散的跳跃进行的，这表明Fis能够稳定DNA交叉。我们的实验表明，Fis可能在体内对细菌染色体的“环域”结构起到稳定作用。
