No sliding during homology search by RecA protein
No sliding during homology search by RecA protein
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DOI：
10.1074/jbc.273.47.31565
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发表时间：
1998-11-20
影响因子：
4.8
通讯作者：
Adzuma, K
中科院分区：
文献类型：
--
作者：
Adzuma, K
大肠杆菌的RecA蛋白是RecA/Rad 51蛋白家族的原型，该蛋白家族存在于几乎所有生物体中。在一个称为DNA突触的过程中，RecA首先聚合到单链DNA（ssDNA）分子上;然后产生的RecA-ssDNA复合物搜索并结合到含有几乎相同或“同源”序列的双链DNA（dsDNA）分子上。因此，RecA-ssDNA复合物可以被设想为序列特异性结合实体。复合体如何寻找隐藏在非特异性序列中的目标？一种可能的机制是滑动机制，其中复合物首先非特异性地结合到dsDNA分子，然后沿着dsDNA线性扩散或滑动。构建了含有串联的四个同源靶标的质粒，并将其用作突触反应中的dsDNA底物。如果滑动是主要的搜索模式，两个最外面的目标应该作为更有效的目标比内部的目标。没有观察到这样的位置偏好，表明RecA-ssDNA复合物的长距离滑动不会发生。这些和其他可用的数据可以充分解释一个简单的三维随机碰撞机制。
The RecA protein of Escherichia coli is a prototype of the RecA/Rad51 family of proteins that exist in virtually all the organisms. In a process called DNA synapsis, RecA first polymerizes onto a single-stranded DNA (ssDNA) molecule; the resulting RecA-ssDNA complex then searches for and binds to a double-stranded DNA (dsDNA) molecule containing the almost identical, or "homologous," sequence. The RecA-ssDNA complex thus can be envisioned as a sequence-specific binding entity. How does the complex search for its target buried within nonspecific sequences? One possible mechanism is the sliding mechanism, in which the complex first binds to a dsDNA molecule nonspecifically and then linearly diffuses, or slides, along the dsDNA To understand the mechanism of homology search by RecA, this sliding model was tested. A plasmid containing four homologous targets in tandem was constructed and used as the dsDNA substrate in the synapsis reaction. If the sliding is the predominant search mode, the two outermost targets should act as more efficient targets than the inner targets. No such positional preference was observed, indicating that a long range sliding of the RecA-ssDNA complex does not occur. These and other available data can be adequately explained by a simple three-dimensional random collision mechanism.