Effects of nucleoid proteins on DNA repression loop formation in Escherichia coli.
Effects of nucleoid proteins on DNA repression loop formation in Escherichia coli.
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DOI：
10.1093/nar/gkm419
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发表时间：
2007
影响因子：
14.9
通讯作者：
Maher LJ 3rd
中科院分区：
文献类型：
--
作者：
Becker NA;Kahn JD;Maher LJ 3rd
DNA固有的硬度限制了它在短时间内弯曲和扭曲的能力，但这种变形是基因调控所必需的。一个经典的范例是DNA环在大肠杆菌lac操纵子的调控。Lac抑制蛋白同时与Lac启动子两侧的两个操作符序列结合。对lac操纵子环依赖性抑制的长度依赖性的分析提供了对细胞内DNA变形能量学的深入了解。DNA的表观柔韧性在体内比在体外更大，可能是因为宿主蛋白结合DNA并诱导柔韧性位点。在这里，我们测试了缺乏类核蛋白HU， IHF或H-NS的细菌菌株的DNA环。我们证实，HU的缺失抑制环，定量模型表明在诱导的操纵子中残留环。IHF基因的缺失影响不大。值得注意的是，DNA环在没有H-NS的情况下被强烈增强，并提出了一个解释模型。氯喹滴定、补骨脂素交联和超卷曲敏感报告基因试验表明，类核蛋白对环的影响与它们对完全或无约束超卷曲的影响无关。这些结果表明宿主类核蛋白可以直接促进或抑制细菌中的DNA环。
The intrinsic stiffness of DNA limits its ability to be bent and twisted over short lengths, but such deformations are required for gene regulation. One classic paradigm is DNA looping in the regulation of the Escherichia coli lac operon. Lac repressor protein binds simultaneously to two operator sequences flanking the lac promoter. Analysis of the length dependence of looping-dependent repression of the lac operon provides insight into DNA deformation energetics within cells. The apparent flexibility of DNA is greater in vivo than in vitro, possibly because of host proteins that bind DNA and induce sites of flexure. Here we test DNA looping in bacterial strains lacking the nucleoid proteins HU, IHF or H-NS. We confirm that deletion of HU inhibits looping and that quantitative modeling suggests residual looping in the induced operon. Deletion of IHF has little effect. Remarkably, DNA looping is strongly enhanced in the absence of H-NS, and an explanatory model is proposed. Chloroquine titration, psoralen crosslinking and supercoiling-sensitive reporter assays show that the effects of nucleoid proteins on looping are not correlated with their effects on either total or unrestrained supercoiling. These results suggest that host nucleoid proteins can directly facilitate or inhibit DNA looping in bacteria.
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影响因子：
14.9
作者：
Dame, RT;Wyman, C;Goosen, N
通讯作者：
Goosen, N
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作者：
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作者：
Dame, RT;Goosen, N
通讯作者：
Goosen, N