Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
Open Biol. 2014 Mar 26;4(3):140006. doi: 10.1098/rsob.140006.
Chromatin-binding proteins must navigate the complex nuclear milieu to find their sites of action, and a constellation of protein factors and other properties are likely to influence targeting specificity. Despite considerable progress, the precise rules by which binding specificity is achieved have remained elusive. Here, we consider early targeting events for two groups of chromatin-binding complexes in Drosophila: the Male-Specific Lethal (MSL) and the Polycomb group (PcG) complexes. These two serve as models for understanding targeting, because they have been extensively studied and play vital roles in Drosophila, and their targets have been documented at high resolution. Furthermore, the proteins and biochemical properties of both complexes are largely conserved in multicellular organisms, including humans. While the MSL complex increases gene expression and PcG members repress genes, the two groups share many similarities such as the ability to modify their chromatin environment to create active or repressive domains, respectively. With legacies of in-depth genetic, biochemical and now genomic approaches, the MSL and PcG complexes will continue to provide tractable systems for understanding the recruitment of multiprotein chromatin complexes to their target loci.
染色质结合蛋白必须在复杂的核环境中导航，以找到其作用位点，并且可能有一系列蛋白质因子和其他特性影响靶向特异性。尽管取得了相当大的进展，但结合特异性是如何实现的精确规则仍然难以捉摸。在这里，我们考虑了果蝇中两组染色质结合复合物的早期靶向事件：雄性致死（MSL）和多梳组（PcG）复合物。这两个复合物作为理解靶向的模型，因为它们已经被广泛研究，在果蝇中发挥着至关重要的作用，并且它们的靶标已经以高分辨率记录下来。此外，这两个复合物的蛋白质和生化特性在包括人类在内的多细胞生物中基本保守。虽然 MSL 复合物增加基因表达，而 PcG 成员抑制基因，但这两个复合物有许多相似之处，例如修饰染色质环境的能力，分别创建活性或抑制性结构域。通过深入的遗传、生化和现在的基因组方法，MSL 和 PcG 复合物将继续为理解多蛋白染色质复合物向其靶标基因座的募集提供易于处理的系统。
