期刊
BIOPHYSICAL JOURNAL
卷 100, 期 8, 页码 2006-2015出版社
CELL PRESS
DOI: 10.1016/j.bpj.2011.02.049
关键词
-
类别
资金
- Spanish Ministry of Science and Innovation [CSD2007-00010, BFU2010-15703/BMC, BFU2008-02328/BMC, FIS2008-0025]
- Comunidad de Madrid [S-0505/MAT/0283]
- Consejeria de Educacion de la Comunidad de Madrid
- European Social Fund
- International Human Frontier Science Program Organization
- European Research Council [206117]
B-A transition and DNA condensation are processes regulated by base sequence and water activity. The constraints imposed by interhelical interactions in condensation compromise the observation of the mechanism by which B and A base-stacking modes influence the global state of the molecule. We used a single-molecule approach to prevent aggregation and mechanical force to control the intramolecular chain association involved in condensation. Force-extension experiments with optical tweezers revealed that DNA stretches as B-DNA under ethanol and spermine concentrations that favor the A-form. Moreover, we found no contour-length change compatible with a cooperative transition between the A and B forms within the intrinsic-force regime. Experiments performed at constant force in the entropic-force regime with magnetic tweezers similarly did not show a bistable contraction of the molecules that could be attributed to the B-A transition when the physiological buffer was replaced by a water-ethanol mixture. A total, stepwise collapse was found instead, which is characteristic of DNA condensation. Therefore, a low-humidity-induced change from the B- to the A-form base-stacking alone does not lead to a contour-length shortening. These results support a mechanism for the B-A transition in which low-humidity conditions locally change the base-stacking arrangement and globally induce DNA condensation, an effect that may eventually stabilize a molecular contour-length reduction.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据