Genetic rearrangement of DNA induces knots with a unique topology: implications for the mechanism of synapsis and crossing-over.
Genetic rearrangement of DNA induces knots with a unique topology: implications for the mechanism of synapsis and crossing-over.
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DNA 的遗传重排产生具有独特拓扑结构的结：对突触和交叉机制的影响。
DOI：
10.1073/pnas.82.10.3124
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发表时间：
1985
影响因子：
11.1
通讯作者：
Nash,HA
中科院分区：
文献类型：
--
作者：
Griffith,JD;Nash,HA
我们已经确定了噬菌体 lambda 整合重组循环产生的结的拓扑符号。为了确保这些结反映反应机制的内在特征，构建了基底，使得 DNA 片段的随机缠绕在拓扑结果中发挥的作用最小。打结的 DNA 被噬菌体 T4 uvsX 基因产物包被，并在电子显微镜下检查以确定每个交叉点或节点的性质。所有的结都是相同的；它们是三叶草，有三个正号节点。我们将这一结果解释为意味着一个重组位点（之前的工作已表明该重组位点被组织成核小体样结构），并以与核小体中发现的相同的旋向性包裹。因此，这种包裹可以解释重组对底物 DNA 超螺旋的依赖性。此外，我们表明拓扑结果极大地限制了链交换细节的可接受机制。
We have determined the topological sign of the knots produced by a cycle of phage lambda integrative recombination. To insure that these knots reflect intrinsic features of the reaction mechanism, the substrate was constructed so that random interwrapping of segments of DNA played a minimal role in the topological outcome. The knotted DNA was coated with the bacteriophage T4 uvsX gene product and examined in the electron microscope to determine the nature of each crossing point or node. All of the knots were identical; they were trefoils with three nodes of positive sign. We interpret this result to mean that one recombination site, which previous work had indicated is organized into a nucleosome-like structure, is wrapped with a handedness identical to that found in nucleosomes. Therefore, this wrapping may explain the dependence of recombination on supercoiling of the substrate DNA. Moreover, we show that the topological result sharply limits acceptable mechanisms for the details of strand exchange.