CNRS UPR9080, Institut de Biologie Physico-Chimique, 13, rue Pierre et Marie Curie, Paris, 75005, France.
Phys Rev Lett. 2010 Jul 2;105(1):018102. doi: 10.1103/PhysRevLett.105.018102. Epub 2010 Jun 29.
DNA supercoiling plays an important role in a variety of cellular processes. The torsional stress related to supercoiling may also be involved in gene regulation through the local structure and dynamics of the double helix. To check this possibility, steady torsional stress was applied in the course of all-atom molecular dynamics simulations of two DNA fragments with different base pair sequences. For one fragment, the torsional stiffness significantly varied with small twisting. The effect is traced to sequence-specific asymmetry of local torsional fluctuations, and it should be small in long random DNA due to compensation. In contrast, the stiffness of special short sequences can change significantly, which gives a simple possibility of gene regulation via probabilities of strong fluctuations. These results have important implications for the role of DNA twisting in complexes with transcription factors.
DNA 超螺旋在多种细胞过程中发挥着重要作用。与超螺旋相关的扭转应力也可能通过双螺旋的局部结构和动力学参与基因调控。为了验证这种可能性，在两个具有不同碱基序列的 DNA 片段的全原子分子动力学模拟过程中施加了稳定的扭转应力。对于一个片段，扭转刚度随小的扭转而显著变化。这种效应可以追溯到局部扭转波动的序列特异性不对称性，而且由于补偿，在长随机 DNA 中应该很小。相比之下，特殊短序列的刚度可以显著变化，这为通过强波动的概率进行基因调控提供了一种简单的可能性。这些结果对 DNA 扭曲在与转录因子形成的复合物中的作用具有重要意义。
