Rudnizky Sergei, Malik Omri, Bavly Adaiah, Pnueli Lilach, Melamed Philippa, Kaplan Ariel
Faculty of Biology, Technion-Israel Institute of Technology, Haifa, 32000, Israel.
Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa, 32000, Israel.
Protein Sci. 2017 Jul;26(7):1266-1277. doi: 10.1002/pro.3159. Epub 2017 Apr 2.
Nucleosomes at the promoters of genes regulate the accessibility of the transcription machinery to DNA, and function as a basic layer in the complex regulation of gene expression. Our understanding of the role of the nucleosome's spontaneous, thermally driven position changes in modulating expression is lacking. This is the result of the paucity of experimental data on these dynamics, at high-resolution, and for DNA sequences that belong to real, transcribed genes. We have developed an assay that uses partial, reversible unzipping of nucleosomes with optical tweezers to repeatedly probe a nucleosome's position over time. Using the nucleosomes at the promoters of two model genes, Cga and Lhb, we show that the mobility of nucleosomes is modulated by the sequence of DNA and by the use of alternative histone variants, and describe how the mobility can affect transcription, at the initiation and elongation phases.
基因启动子处的核小体调节转录机器与DNA的可及性，并在基因表达的复杂调控中作为基础层面发挥作用。我们对核小体自发的、热驱动的位置变化在调节基因表达中的作用尚缺乏了解。这是由于关于这些动力学的高分辨率实验数据匮乏，且缺乏针对真实转录基因的DNA序列的数据。我们开发了一种检测方法，利用光镊对核小体进行部分、可逆的解链，以随时间反复探测核小体的位置。利用两个模型基因Cga和Lhb启动子处的核小体，我们表明核小体的迁移率受DNA序列和替代组蛋白变体的使用所调节，并描述了迁移率如何在起始和延伸阶段影响转录。
