Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA 02215, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.
Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA 02215, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Biological and Biomedical Sciences Graduate Program, Harvard Medical School, Boston, MA 02215, USA.
Cell. 2018 Nov 15;175(5):1272-1288.e20. doi: 10.1016/j.cell.2018.09.032. Epub 2018 Oct 18.
Mammalian SWI/SNF (mSWI/SNF) ATP-dependent chromatin remodeling complexes are multi-subunit molecular machines that play vital roles in regulating genomic architecture and are frequently disrupted in human cancer and developmental disorders. To date, the modular organization and pathways of assembly of these chromatin regulators remain unknown, presenting a major barrier to structural and functional determination. Here, we elucidate the architecture and assembly pathway across three classes of mSWI/SNF complexes-canonical BRG1/BRM-associated factor (BAF), polybromo-associated BAF (PBAF), and newly defined ncBAF complexes-and define the requirement of each subunit for complex formation and stability. Using affinity purification of endogenous complexes from mammalian and Drosophila cells coupled with cross-linking mass spectrometry (CX-MS) and mutagenesis, we uncover three distinct and evolutionarily conserved modules, their organization, and the temporal incorporation of these modules into each complete mSWI/SNF complex class. Finally, we map human disease-associated mutations within subunits and modules, defining specific topological regions that are affected upon subunit perturbation.
哺乳动物 SWI/SNF（mSWI/SNF）ATP 依赖性染色质重塑复合物是多亚基分子机器，在调节基因组结构方面发挥着重要作用，并且在人类癌症和发育障碍中经常被破坏。迄今为止，这些染色质调节剂的模块化组织和组装途径仍然未知，这对结构和功能的确定构成了重大障碍。在这里，我们阐明了三类 mSWI/SNF 复合物——规范的 BRG1/BRM 相关因子（BAF）、多溴相关 BAF（PBAF）和新定义的 ncBAF 复合物——的结构和组装途径，并确定了每个亚基对于复合物形成和稳定性的要求。我们使用来自哺乳动物和果蝇细胞的内源性复合物的亲和纯化，结合交联质谱（CX-MS）和突变分析，揭示了三个不同的且进化上保守的模块、它们的组织以及这些模块在每个完整的 mSWI/SNF 复合物类中的时间整合。最后，我们在亚基和模块内绘制了与人类疾病相关的突变，定义了在亚基扰动时受到影响的特定拓扑区域。
