Syed Sajad Hussain, Goutte-Gattat Damien, Becker Nils, Meyer Sam, Shukla Manu Shubhdarshan, Hayes Jeffrey J, Everaers Ralf, Angelov Dimitar, Bednar Jan, Dimitrov Stefan
Institut National de la Santé et de la Recherche Médicale, Université Joseph Fourier-Grenoble, Grenoble Cedex 9, France.
Proc Natl Acad Sci U S A. 2010 May 25;107(21):9620-5. doi: 10.1073/pnas.1000309107. Epub 2010 May 10.
Despite the key role of the linker histone H1 in chromatin structure and dynamics, its location and interactions with nucleosomal DNA have not been elucidated. In this work we have used a combination of electron cryomicroscopy, hydroxyl radical footprinting, and nanoscale modeling to analyze the structure of precisely positioned mono-, di-, and trinucleosomes containing physiologically assembled full-length histone H1 or truncated mutants of this protein. Single-base resolution *OH footprinting shows that the globular domain of histone H1 (GH1) interacts with the DNA minor groove located at the center of the nucleosome and contacts a 10-bp region of DNA localized symmetrically with respect to the nucleosomal dyad. In addition, GH1 interacts with and organizes about one helical turn of DNA in each linker region of the nucleosome. We also find that a seven amino acid residue region (121-127) in the COOH terminus of histone H1 was required for the formation of the stem structure of the linker DNA. A molecular model on the basis of these data and coarse-grain DNA mechanics provides novel insights on how the different domains of H1 interact with the nucleosome and predicts a specific H1-mediated stem structure within linker DNA.
尽管连接组蛋白H1在染色质结构和动力学中起着关键作用，但其与核小体DNA的位置及相互作用尚未阐明。在这项工作中，我们结合了电子冷冻显微镜、羟基自由基足迹法和纳米尺度建模，来分析包含生理组装的全长组蛋白H1或该蛋白截短突变体的精确定位的单核小体、双核小体和三核小体的结构。单碱基分辨率的羟基自由基足迹法表明，组蛋白H1的球状结构域（GH1）与位于核小体中心的DNA小沟相互作用，并接触相对于核小体二分体对称定位的10个碱基对的DNA区域。此外，GH1在核小体的每个连接区与约一圈螺旋的DNA相互作用并对其进行组织。我们还发现，组蛋白H1羧基末端的一个七氨基酸残基区域（121 - 127）是连接DNA茎结构形成所必需的。基于这些数据和粗粒度DNA力学的分子模型，为H1的不同结构域如何与核小体相互作用提供了新的见解，并预测了连接DNA内特定的H1介导的茎结构。
