Adkins Nicholas L, McBryant Steve J, Johnson Cotteka N, Leidy Jennifer M, Woodcock Christopher L, Robert Charles H, Hansen Jeffrey C, Georgel Philippe T
Department of Biological Sciences and Cell Differentiation and Development Center, Marshall University, Huntington, West Virginia 25755, USA.
Biochemistry. 2009 Jan 20;48(2):276-88. doi: 10.1021/bi801705g.
Recent studies of the mechanisms involved in the regulation of gene expression in eukaryotic organisms depict a highly complex process requiring a coordinated rearrangement of numerous molecules to mediate DNA accessibility. Silencing in Saccharomyces cerevisiae involves the Sir family of proteins. Sir3p, originally described as repressing key areas of the yeast genome through interactions with the tails of histones H3 and H4, appears to have additional roles in that process, including involvement with a DNA binding component. Our in vitro studies focused on the characterization of Sir3p-nucleic acid interactions and their biological functions in Sir3p-mediated silencing using binding assays, EM imaging, and theoretical modeling. Our results suggest that the initial Sir3p recruitment is partially DNA-driven, highly cooperative, and dependent on nucleosomal features other than histone tails. The initial step appears to be rapidly followed by the spreading of silencing using linker DNA as a track.
最近对真核生物基因表达调控机制的研究描绘了一个高度复杂的过程，该过程需要众多分子的协同重排来介导DNA的可及性。酿酒酵母中的沉默涉及Sir蛋白家族。Sir3p最初被描述为通过与组蛋白H3和H4的尾部相互作用来抑制酵母基因组的关键区域，在该过程中似乎还有其他作用，包括与一种DNA结合成分有关。我们的体外研究集中于使用结合测定、电子显微镜成像和理论建模来表征Sir3p与核酸的相互作用及其在Sir3p介导的沉默中的生物学功能。我们的结果表明，Sir3p的初始募集部分由DNA驱动，具有高度协同性，并且依赖于除组蛋白尾部之外的核小体特征。初始步骤之后似乎迅速发生了以连接DNA为轨道的沉默传播。
