Facilitated diffusion of a DNA binding protein on chromatin.
Facilitated diffusion of a DNA binding protein on chromatin.
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促进 DNA 结合蛋白在染色质上的扩散。
DOI：
10.1002/j.1460-2075.1986.tb04645.x
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发表时间：
1986
期刊：
影响因子：
--
通讯作者：
H. Gould
中科院分区：
文献类型：
--
作者：
R. Hannon;E. Richards;H. Gould
易化扩散解释了许多细菌DNA结合蛋白与体外特异性DNA序列的快速结合。在这种机制中，蛋白质随机结合到DAN上的非特异性位点，并沿着DNA链扩散（通过“滑动”或“跳跃”），直到它们到达其特定的功能位点。我们已经研究了这种机制是否可以在染色质中使用细菌DNA结合蛋白，大肠杆菌RNA聚合酶，依赖于线性扩散定位DNA上的起始位点。我们已经测量了染色质和它的游离DNA之间的竞争形成的起始复合物。只有通过去除组蛋白H1而暴露的短连接片段可用于与聚合酶相互作用，但是这种多核小体链的连接DNA上的稀疏分布的启动子位点与DNA上的启动子位点以相同的速率定位。我们的结论是，聚合酶是自由迁移之间的多核小体链的单独的接头DNA片段，以达到启动子位点。因此，这条链允许蛋白质在相邻的接头片段之间“跳跃”，以寻找可接近的DNA上的靶位点。
Facilitated diffusion accounts for the rapid rate of association of many bacterial DNA binding proteins with specific DNA sequences in vitro. In this mechanism the proteins bind at random to non‐specific sites on the DAN and diffuse (by ‘sliding’ or ‘hopping’) along the DNA chain until they arrive at their specific functional sites. We have investigated whether such a mechanism can operate in chromatin by using a bacterial DNA binding protein, Escherichia coli RNA polymerase, that depends on linear diffusion to locate initiation sites on DNA. We have measured the competition between chromatin and its free DNA for the formation of initiation complexes. Only the short linker segments exposed by the removal of histone H1 are available for interaction with the polymerase, but the sparsely distributed promoter sites on the linker DNA of such a polynucleosome chain are located at the same rate as those on DNA. We conclude that the polymerase is free to migrate between the separate linker DNA segments of a polynucleosome chain to reach a promoter site. This chain thus permits the ‘hopping’ of proteins between neighboring linker segments in their search for a target site on the accessible DNA.