Mechanical Properties of High-G.C Content DNA with A-Type Base-Stacking
Mechanical Properties of High-G.C Content DNA with A-Type Base-Stacking
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DOI：
10.1016/j.bpj.2011.02.051
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发表时间：
2011-04-20
影响因子：
3.4
通讯作者：
Ricardo Arias-Gonzalez, J.
中科院分区：
文献类型：
--
作者：
Hormeno, Silvia;Ibarra, Borja;Ricardo Arias-Gonzalez, J.
已知DNA分子的序列会影响其二级结构和柔性。使用散装和单分子技术相结合，我们测量的结构和力学性能的两个DNA的序列和碱基堆积在水性缓冲液中的安排，所揭示的圆二色性：一个与50%的G. C含量和B-型和其他与70%的G. C含量和A-型。原子力显微镜的测量结果表明，局部A型结构的高G. C的DNA不会导致一个整体的轮廓长度减少相对于B型的分子，虽然它会影响其持久性长度。然而，在力的存在下，高G. C含量的DNA的刚度是类似的平衡G. C DNA的磁性和光学镊子测量的持久性长度的两个DNA基板的典型值。这表明，序列诱导的局部变形从B-形式的张力下妥协。最后，高G. C DNA比50%-G.C DNA明显更难拉伸，如由较大的拉伸模量所证明的。我们的研究结果表明，由高G. C含量诱导的DNA的局部碱基对构型影响聚合物的拉伸弹性，但它不影响全局双螺旋排列。
The sequence of a DNA molecule is known to influence its secondary structure and flexibility. Using a combination of bulk and single-molecule techniques, we measure the structural and mechanical properties of two DNAs which differ in both sequence and base-stacking arrangement in aqueous buffer, as revealed by circular dichroism: one with 50% G.C content and B-form and the other with 70% G.C content and A-form. Atomic force microscopy measurements reveal that the local A-form structure of the high-G.C DNA does not lead to a global contour-length decrease with respect to that of the molecule in B-form although it affects its persistence length. In the presence of force, however, the stiffness of high-G.C content DNA is similar to that of balanced-G.C DNA as magnetic and optical tweezers measured typical values for the persistence length of both DNA substrates. This indicates that sequence-induced local distortions from the B-form are compromised under tension. Finally, high-G.C DNA is significantly harder to stretch than 50%-G.C DNA as manifested by a larger stretch modulus. Our results show that a local, basepair configuration of DNA induced by high-G.C content influences the stretching elasticity of the polymer but that it does not affect the global, double-helix arrangement.