DNA bending in the Sin recombination synapse: functional replacement of HU by IHF
DNA bending in the Sin recombination synapse: functional replacement of HU by IHF
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DOI：
10.1111/j.1365-2958.2006.05064.x
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发表时间：
2006-03-01
影响因子：
3.6
通讯作者：
Stark, WM
中科院分区：
文献类型：
--
作者：
Rowland, SJ;Boocock, MR;Stark, WM
丝氨酸重组酶 Sin 需要非特异性 DNA 弯曲蛋白（例如 Hbsu）才能在其重组位点 resH 发挥活性。 Hbsu 和 Sin 亚基结合在 resH 位点 II 上，共同调节重组，通过指定相互缠绕的突触组装来确保直接重复的 resH 位点的选择性。为了研究 DNA 弯曲蛋白在定义突触结构中的作用，我们构建了一个嵌合重组位点 (resF)，该位点允许 Hbsu 被 IHF 取代，在位点 I（交叉位点）和位点 II 之间特异性结合。两个 Sin 二聚体和一个 IHF 二聚体可以与 resF 中紧密相邻的位点结合在一起，形成折叠复合物。 IHF 位点在位点 I-位点 II 间隔区中的精确位置决定了这些复合物的构象，以及重组测定中 resF 位点的反应性。数据表明，间隔 DNA 中需要具有特定几何形状的急剧弯曲，才能将位点 I 和 II 处的 Sin 二聚体以正确的相对方向聚集在一起，以进行突触组装和调节，这与我们的高度浓缩突触模型一致，其中 Hbsu/IHF 具有纯粹的结构功能。
The serine recombinase Sin requires a non-specific DNA-bending protein such as Hbsu for activity at its recombination site resH. Hbsu, and Sin subunits bound at site II of resH, together regulate recombination, ensuring selectivity for directly repeated resH sites by specifying assembly of an intertwined synapse. To investigate the role of the DNA-bending protein in defining the architecture of the synapse, we constructed a chimaeric recombination site (resF) which allows Hbsu to be substituted by IHF, binding specifically between site I (the crossover site) and site II. Two Sin dimers and one IHF dimer can bind together to the closely adjoining sites in resF, forming folded complexes. The precise position of the IHF site within the site I-site II spacer determines the conformation of these complexes, and also the reactivity of the resF sites in recombination assays. The data suggest that a sharp bend with a specific geometry is required in the spacer DNA, to bring the Sin dimers at sites I and II together in the correct relative orientation for synapse assembly and regulation, consistent with our model for a highly condensed synapse in which Hbsu/IHF has a purely architectural function.