Integration host factor (IHF) dictates the structure of polyamine-DNA condensates: implications for the role of IHF in the compaction of bacterial chromatin.
Integration host factor (IHF) dictates the structure of polyamine-DNA condensates: implications for the role of IHF in the compaction of bacterial chromatin.
复制标题
DOI：
10.1021/bi8019965
复制
发表时间：
2009-01
期刊：
影响因子：
2.9
通讯作者：
Tumpa Sarkar;A. Petrov;Jason R Vitko;C. Santai;S. Harvey;I. Mukerji;N. Hud
中科院分区：
文献类型：
--
作者：
Tumpa Sarkar;A. Petrov;Jason R Vitko;C. Santai;S. Harvey;I. Mukerji;N. Hud
整合宿主因子(IHF)是细菌细胞中的一种类核相关蛋白，与包括DNA压缩在内的许多染色体功能有关。IHF以微摩尔亲和力与所有双链DNA结合，并在序列特异性位点以更高的亲和力结合。已知IHF在这两种结合模式下都能引起DNA螺旋轴的急剧弯曲，但IHF在控制细菌细胞内DNA缩合中的作用尚不确定。在这里，我们证明了IHF在体外影响了多胺缩合的DNA的形态。在没有IHF的情况下，亚精胺和精胺主要将DNA凝聚成环状结构，而在IHF存在的情况下，多胺主要将DNA凝聚成棒状结构。对没有IHF结合和存在IHF结合的DNA缩合的计算机模拟支持了我们的模型，在该模型中，DNA弯曲蛋白，如IHF和Hu，通过提供在凝聚的DNA线束末端弯曲DNA所需的自由能，促进DNA缩合成棒状结构。我们认为IHF和HU在细菌细胞中的一个共同功能是通过引入染色体DNA的急剧弯曲来促进类核DNA的组织。
Integration host factor (IHF), a nucleoid-associated protein in bacterial cells, is implicated in a number of chromosomal functions including DNA compaction. IHF binds to all duplex DNA with micromolar affinity and at sequence-specific sites with much higher affinity. IHF is known to induce sharp bends in the helical axis of DNA in both modes of binding, but the role of IHF in controlling DNA condensation within bacterial cells has remained undetermined. Here we demonstrate that IHF influences the morphology of DNA condensed by polyamines in vitro. In the absence of IHF, spermidine and spermine condense DNA primarily into toroidal structures, whereas in the presence of IHF, polyamines condense DNA primarily into rodlike structures. Computer simulations of DNA condensation in the absence and presence of IHF binding lend support to our model in which DNA bending proteins, such as IHF and HU, promote the condensation of DNA into rodlike structures by providing the free energy necessary to bend DNA at the ends of linear bundles of condensed DNA. We propose that a common function of IHF and HU in bacterial cells is to facilitate DNA organization in the nucleoid by the introduction of sharp bends in chromosomal DNA.