Strick T R, Croquette V, Bensimon D
Laboratoire de Physique Statistique, Ecole Normale Superieure, 24 rue Lhomond, 75006 Paris, France.
Proc Natl Acad Sci U S A. 1998 Sep 1;95(18):10579-83. doi: 10.1073/pnas.95.18.10579.
By using elastic measurements on single DNA molecules, we show that stretching a negatively supercoiled DNA activates homologous pairing in physiological conditions. These experiments indicate that a stretched unwound DNA locally denatures to alleviate the force-driven increase in torsional stress. This is detected by hybridization with 1 kb of homologous single-stranded DNA probes. The stretching force involved (approximately 2 pN) is small compared with those typically developed by molecular motors, suggesting that this process may be relevant to DNA processing in vivo. We used this technique to monitor the progressive denaturation of DNA as it is unwound and found that distinct, stable denaturation bubbles formed, beginning in A+T-rich regions.
通过对单个DNA分子进行弹性测量，我们发现，在生理条件下拉伸负超螺旋DNA会激活同源配对。这些实验表明，拉伸解旋的DNA会局部变性，以缓解力驱动的扭转应力增加。这可通过与1 kb的同源单链DNA探针杂交来检测。与分子马达通常产生的力相比，所涉及的拉伸力（约2皮牛）较小，这表明该过程可能与体内DNA加工有关。我们使用该技术监测DNA解旋时的渐进变性，发现从富含A+T的区域开始形成了明显、稳定的变性泡。
