半乳糖阻遏物包含一个反向平行的DNA环。

Gal repressosome contains an antiparallel DNA loop.

作者信息

Geanacopoulos M, Vasmatzis G, Zhurkin V B, Adhya S

机构信息

Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.

出版信息

Nat Struct Biol. 2001 May;8(5):432-6. doi: 10.1038/87595.

DOI:10.1038/87595

PMID:11323719

Abstract

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.

摘要

在大肠杆菌中，当两个二聚体GalR蛋白和类组蛋白HU蛋白结合到同源位点导致DNA环化时，半乳糖阻遏物组装和半乳糖操纵子的阻遏就会发生。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。利用操纵基因间DNA的序列依赖性结构参数以及由GalR和不对称HU结合引起的构象变化，构建了与GalR四聚体构型兼容的四种可能DNA环的立体化学模型。对它们的DNA弹性能的评估明确表明，优先选择一种环结构，其中两个半乳糖操纵基因采取反平行方向，导致DNA解旋。