Compaction of single DNA molecules induced by binding of integration host factor (IHF)
Compaction of single DNA molecules induced by binding of integration host factor (IHF)
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DOI：
10.1073/pnas.181029198
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发表时间：
2001-09-11
影响因子：
11.1
通讯作者：
Stavans, J
中科院分区：
文献类型：
--
作者：
Ali, BMJ;Amit, R;Stavans, J
我们研究了整合宿主因子（IHF），细菌中的一个主要的核相关蛋白，和单个DNA分子之间的相互作用。对λ DNA的力延伸测量和对由单个短DNA分子拴在表面上的小珠的布朗运动的分析表明：（i）DNA-IHF复合物对于零或小的张力值保持随机的、尽管更紧凑的卷曲构型，（ii）IHF通过以低特异性结合多个DNA位点诱导DNA压缩，以及（iii）随着DNA上张力的增加，裸DNA的弹性性质恢复。这种行为与统计力学模型的预测一致，该模型描述了蛋白质如何通过DNA分子上施加的张力来弯曲DNA。从模型中获得的DNA-IHF复合物中结合IHF的量的估计值与从DNA-IHF交联分析中获得的该量的独立测量值非常一致。我们的研究结果支持了长期以来的观点，即IHF和其他组蛋白样蛋白在塑造细菌类核的长尺度结构中起着重要作用。
We studied the interaction between the integration host factor (IHF), a major nucleoid-associated protein in bacteria, and single DNA molecules. Force-extension measurements of lambda DNA and an analysis of the Brownian motion of small beads tethered to a surface by single short DNA molecules, in equilibrium with an IHF solution, indicate that: (i) the DNA-IHF complex retains a random, although more compact, coiled configuration for zero or small values of the tension, (ii) IHF induces DNA compaction by binding to multiple DNA sites with low specificity, and (iii) with increasing tension on the DNA, the elastic properties of bare DNA are recovered. This behavior is consistent with the predictions of a statistical mechanical model describing how proteins bending DNA are driven off by an applied tension on the DNA molecule. Estimates of the amount of bound IHF in DNA-IHF complexes obtained from the model agree very well with independent measurements of this quantity obtained from the analysis of DNA-IHF crosslinking. Our findings support the long-held view that IHF and other histone-like proteins play an important role in shaping the long-scale structure of the bacterial nucleoid.