Ramanathan Subramanian P, van Aelst Kara, Sears Alice, Peakman Luke J, Diffin Fiona M, Szczelkun Mark D, Seidel Ralf
BIOTEChnology Center Dresden, Dresden University of Technology, 01062 Dresden, Germany.
Proc Natl Acad Sci U S A. 2009 Feb 10;106(6):1748-53. doi: 10.1073/pnas.0807193106. Epub 2009 Jan 30.
To cleave DNA, Type III restriction enzymes must communicate the relative orientation of two asymmetric recognition sites over hundreds of base pairs. The basis of this long-distance communication, for which ATP hydrolysis by their helicase domains is required, is poorly understood. Several conflicting DNA-looping mechanisms have been proposed, driven either by active DNA translocation or passive 3D diffusion. Using single-molecule DNA stretching in combination with bulk-solution assays, we provide evidence that looping is both highly unlikely and unnecessary, and that communication is strictly confined to a 1D route. Integrating our results with previous data, a simple communication scheme is concluded based on 1D diffusion along DNA.
为了切割DNA,III型限制酶必须在数百个碱基对上传递两个不对称识别位点的相对方向。这种长距离通讯的基础尚不清楚,而其解旋酶结构域的ATP水解是必需的。已经提出了几种相互矛盾的DNA环化机制,这些机制要么由活跃的DNA易位驱动,要么由被动的三维扩散驱动。通过结合单分子DNA拉伸和整体溶液分析,我们提供的证据表明,环化极不可能发生且没有必要,并且通讯严格限于一维路径。将我们的结果与先前的数据相结合,基于沿DNA的一维扩散得出了一个简单的通讯方案。