Huang Ying, Myers Michael P, Xu Rui-Ming
Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA.
Structure. 2006 Apr;14(4):703-12. doi: 10.1016/j.str.2006.01.007.
Heterochromatin protein-1 (HP1) plays an essential role in both the assembly of higher-order chromatin structure and epigenetic inheritance. The C-terminal chromo shadow domain (CSD) of HP1 is responsible for homodimerization and interaction with a number of chromatin-associated nonhistone proteins, including EMSY, which is a BRCA2-interacting protein that has been implicated in the development of breast and ovarian cancer. We have determined the crystal structure of the HP1beta CSD in complex with the N-terminal domain of EMSY at 1.8 A resolution. Surprisingly, the structure reveals that EMSY is bound by two HP1 CSD homodimers, and the binding sequences differ from the consensus HP1 binding motif PXVXL. This structural information expands our understanding of HP1 binding specificity and provides insights into interactions between HP1 homodimers that are likely to be important for heterochromatin formation.
异染色质蛋白1（HP1）在高阶染色质结构组装和表观遗传继承中都起着至关重要的作用。HP1的C端染色体阴影结构域（CSD）负责同源二聚化以及与许多染色质相关的非组蛋白相互作用，包括EMSY，EMSY是一种与BRCA2相互作用的蛋白，与乳腺癌和卵巢癌的发生有关。我们已经确定了HP1β CSD与EMSY N端结构域复合物的晶体结构，分辨率为1.8埃。令人惊讶的是，该结构显示EMSY由两个HP1 CSD同源二聚体结合，且结合序列不同于HP1结合基序PXVXL的共有序列。这一结构信息扩展了我们对HP1结合特异性的理解，并为HP1同源二聚体之间的相互作用提供了见解，而这种相互作用可能对异染色质形成很重要。
