Structural and mechanical properties of individual human telomeric G-quadruplexes in molecularly crowded solutions.
Structural and mechanical properties of individual human telomeric G-quadruplexes in molecularly crowded solutions.
复制标题
DOI：
10.1093/nar/gkt038
复制
发表时间：
2013-04-01
影响因子：
14.9
通讯作者：
Mao H
中科院分区：
文献类型：
--
作者：
Dhakal S;Cui Y;Koirala D;Ghimire C;Kushwaha S;Yu Z;Yangyuoru PM;Mao H
最近的实验提供了有争议的观察结果，即模拟细胞环境的分子拥挤缓冲液中存在平行或非平行的 G-四链体。在这里，我们使用激光镊子沿着三个不同的轨迹机械地展开人类端粒 DNA 片段 5'-(TTAGGG)4TTA 中的结构。测量每个展开几何形状的端到端距离后，将其与 PDB 结构进行比较，以确定最匹配的 G-四链体构象。该方法非常适合在不适合常规方法的复杂环境中识别生物分子结构，例如在混合物种的溶液中或在生理上显着的浓度下。通过这种方法，我们发现平行 G-四链体与非平行物质（1:1 比例）共存于含有脱水共溶质 [40% w/v 二甲基亚砜 (DMSO) 或乙腈 (ACN)] 的拥挤缓冲液中。在具有空间共溶质 [40% w/v 牛血清白蛋白 (BSA)] 的拥挤溶液中，平行 G-四链体仅占总体的 10%。这种差异明确支持脱水促进平行 G 四链体形成的观点。与在拥挤 (9 pN) 和稀释 (15 pN) 缓冲液中解折叠力降低的 DNA 发夹相比，G-四链体的解折叠力保持不变 (20 pN)。这样的结果意味着，在细胞环境中，DNA G-四链体，而不是发夹，可以以通常小于 20 pN 的失速力来阻止 DNA/RNA 聚合酶。
Recent experiments provided controversial observations that either parallel or non-parallel G-quadruplex exists in molecularly crowded buffers that mimic cellular environment. Here, we used laser tweezers to mechanically unfold structures in a human telomeric DNA fragment, 5′-(TTAGGG)4TTA, along three different trajectories. After the end-to-end distance of each unfolding geometry was measured, it was compared with PDB structures to identify the best-matching G-quadruplex conformation. This method is well-suited to identify biomolecular structures in complex settings not amenable to conventional approaches, such as in a solution with mixed species or at physiologically significant concentrations. With this approach, we found that parallel G-quadruplex coexists with non-parallel species (1:1 ratio) in crowded buffers with dehydrating cosolutes [40% w/v dimethyl sulfoxide (DMSO) or acetonitrile (ACN)]. In crowded solutions with steric cosolutes [40% w/v bovine serum albumin (BSA)], the parallel G-quadruplex constitutes only 10% of the population. This difference unequivocally supports the notion that dehydration promotes the formation of parallel G-quadruplexes. Compared with DNA hairpins that have decreased unfolding forces in crowded (9 pN) versus diluted (15 pN) buffers, those of G-quadruplexes remain the same (20 pN). Such a result implies that in a cellular environment, DNA G-quadruplexes, instead of hairpins, can stop DNA/RNA polymerases with stall forces often <20 pN.
登录
查看更多内容
影响因子：
5.6
作者：
Mills, JB;Vacano, E;Hagerman, PJ
通讯作者：
Hagerman, PJ
影响因子：
15
作者：
Miller, M. Clarke;Buscaglia, Robert;Trent, John O.
通讯作者：
Trent, John O.
DOI：
10.1073/pnas.0508584102
发表时间：
2005-11-29
影响因子：
11.1
作者：
Laurence, TA;Kong, XX;Weiss, S
通讯作者：
Weiss, S
DOI：
10.1073/pnas.0509217103
发表时间：
2006-01-31
影响因子：
11.1
作者：
Dietz, H;Rief, M
通讯作者：
Rief, M
影响因子：
15
作者：
Miyoshi, Daisuke;Nakamura, Kaori;Sugimoto, Naoki
通讯作者：
Sugimoto, Naoki