Lia Giuseppe, Praly Elise, Ferreira Helder, Stockdale Chris, Tse-Dinh Yuk Ching, Dunlap David, Croquette Vincent, Bensimon David, Owen-Hughes Tom
Laboratoire de Physique Statistique and Department Biologie, Ecole Normale Supérieure, CNRS-UMR 8550, 24 rue Lhomond, 75231 Paris Cedex 05, France.
Mol Cell. 2006 Feb 3;21(3):417-25. doi: 10.1016/j.molcel.2005.12.013.
The Snf2 family represents a functionally diverse class of ATPase sharing the ability to modify DNA structure. Here, we use a magnetic trap and an atomic force microscope to monitor the activity of a member of this class: the RSC complex. This enzyme caused transient shortenings in DNA length involving translocation of typically 400 bp within 2 s, resulting in the formation of a loop whose size depended on both the force applied to the DNA and the ATP concentration. The majority of loops then decrease in size within a time similar to that with which they are formed, suggesting that the motor has the ability to reverse its direction. Loop formation was also associated with the generation of negative DNA supercoils. These observations support the idea that the ATPase motors of the Snf2 family of proteins act as DNA translocases specialized to generate transient distortions in DNA structure.
Snf2家族代表了一类功能多样的ATP酶，它们具有改变DNA结构的能力。在这里，我们使用磁镊和原子力显微镜来监测该家族一个成员的活性：RSC复合物。这种酶会导致DNA长度的短暂缩短，通常在2秒内移动400碱基对，从而形成一个环，其大小取决于施加在DNA上的力和ATP浓度。然后，大多数环在形成后的一段时间内尺寸减小，这表明该分子马达有能力反转其方向。环的形成还与负DNA超螺旋的产生有关。这些观察结果支持了这样一种观点，即Snf2家族蛋白质的ATP酶分子马达作为DNA转位酶，专门用于在DNA结构中产生短暂的扭曲。
