Gal repressosome contains an antiparallel DNA loop
Gal repressosome contains an antiparallel DNA loop
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DOI：
10.1038/87595
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发表时间：
2001-05-01
期刊：
影响因子：
--
通讯作者：
Adhya, S
中科院分区：
文献类型：
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作者：
Geanacopoulos, M;Vasmatzis, G;Adhya, S
当两个二聚体 GalR 蛋白和组蛋白样 HU 蛋白结合到同源位点导致 DNA 成环时，大肠杆菌中的 Gal 阻抑体组装和 gal 操纵子的抑制就会发生。基于结构的遗传分析确定了 GalR 表面相互作用形成堆叠的 V 形四聚体结构。使用互操作者 DNA 的序列依赖性结构参数以及 GalR 和不对称 HU 结合引起的构象变化，构建了与 GalR 四聚体配置兼容的四种可能的 DNA 环的立体化学模型。对它们 DNA 弹性能的评估明确偏向于环结构，其中两个 gal 操作符采用反平行方向，导致 DNA 扭转不足。
Gal repressosome assembly and repression of the gal operon in Escherichia coli occurs when two dimeric GalR proteins and the histone-like HU protein bind to cognate sites causing DNA looping. Structure-based genetic analysis defined the GalR surfaces interacting to form a stacked, V-shaped, tetrameric structure. Stereochemical models of the four possible DNA loops compatible with the GalR tetramer configuration were constructed using the sequence-dependent structural parameters of the interoperator DNA and conformation changes caused by GalR and asymmetric HU binding. Evaluation of their DNA elastic energies gave unambiguous preference to a loop structure in which the two gal operators adopt an antiparallel orientation causing undertwisting of DNA.