The Contribution of Backbone Electrostatic Repulsion to DNA Mechanical Properties is Length-Scale-Dependent
The Contribution of Backbone Electrostatic Repulsion to DNA Mechanical Properties is Length-Scale-Dependent
复制标题
主链静电斥力对 DNA 机械性能的贡献与长度尺度相关
DOI：
10.1021/acs.jpclett.9b01960
复制
发表时间：
2019
影响因子：
5.7
通讯作者：
Wales David J
中科院分区：
文献类型：
--
作者：
Xiao Shiyan;Liang Haojun;Wales David J
DNA弯曲的机制与许多重要的生物过程密切相关。最近的实验报告了DNA在短长度尺度上的异常柔性，这让人们对该地区谐和蠕虫链(WLC)模型的有效性产生了怀疑。在本工作中，我们系统地探讨了DNA在不同长度尺度上的弯曲动力学。与WLC描述的少于3个螺旋的DNA双链的显著偏离相反，我们的原子学研究表明，中性“零异构体”的行为符合理想的弹性WLC，并且局部弯曲的方向关联表现出均匀的衰减。骨架中和减弱了以前在正常DNA中观察到的有效弯曲偏好的各向异性和弯曲相关的螺旋周期。静电斥力对DNA链的拉伸协作性和力学性能的贡献与长度有关：磷酸盐中和增加了DNA在两个螺旋转弯以下的硬度，但对较长的链则降低。我们发现DNA的刚性在很大程度上是由碱基对堆积决定的，静电相互作用只占总持续长度的10%左右。
The mechanics of DNA bending is crucially related to many vital biological processes. Recent experiments reported anomalous flexibility for DNA on short length scales, calling into doubt the validity of the harmonic worm-like chain (WLC) model in this region. In the present work, we systematically probed the bending dynamics of DNA at different length scales. In contrast to the remarkable deviation from the WLC description for DNA duplexes of less than three helical turns, our atomistic studies indicate that the neutral “null isomer” behaves in accord with the ideal elastic WLC and exhibits a uniform decay for the directional correlation of local bending. The backbone neutralization weakens the anisotropy in the effective bending preference and the helical periodicity of bend correlation that have previously been observed for normal DNA. The contribution of electrostatic repulsion to stretching cooperativity and the mechanical properties of DNA strands is length-scale-dependent: the phosphate neutralization increases the stiffness of DNA below two helical turns, but it is decreased for longer strands. We find that DNA rigidity is largely determined by base pair stacking, with electrostatic interactions contributing only around 10% of the total persistence length.