ATP依赖性SWI/SNF染色质重塑复合物是保守的多亚基组件,可控制基因组活性。SWI/SNF复合物在植物发育和生长中的功能已经得到了很好的确立,但是特定组件的体系结构尚不清楚。在这项研究中,我们阐明了在BRM催化亚基周围形成的拟南芥SWI/SNF复合物的组织,并定义整个复合物的形成和稳定性对含溴结构域蛋白BRD1/2/13的要求。使用亲和纯化,然后进行质谱分析,我们确定了一组与BRM相关的亚基,并证明了BRM复合物与哺乳动物的非规范BAF复合物非常相似。此外,我们将BDH1和2蛋白鉴定为BRM复合物的组成部分,使用突变分析,表明BDH1/2对营养和生殖发育很重要,以及荷尔蒙的反应。我们进一步表明,BRD1/2/13代表BRM复合物的独特亚基,它们的损耗严重影响了建筑群的完整性,导致残余组件的形成。最后,蛋白酶体抑制后的BRM复合物的分析揭示了由ATPase组成的模块的存在,ARP,和BDH蛋白,以依赖BRD的方式与其他亚基组装。一起,我们的结果提示了植物SWI/SNF复合物的模块化组织,并为突变表型提供了生化解释.
ATP-dependent SWI/SNF chromatin remodelling complexes are conserved multi-subunit assemblies that control genome activity. Functions of SWI/SNF complexes in plant development and growth have been well established, but the architecture of particular assemblies is unclear. In this study, we elucidate the organization of Arabidopsis SWI/SNF complexes formed around a
BRM catalytic subunit, and define the requirement of bromodomain-containing proteins BRD1/2/13 for the formation and stability of the entire complex. Using affinity purification followed by mass spectrometry, we identify a set of
BRM-associated subunits and demonstrate that the
BRM complexes strongly resemble mammalian non-canonical BAF complexes. Furthermore, we identify BDH1 and 2 proteins as components of the
BRM complex and, using mutant analyses, show that BDH1/2 are important for vegetative and generative development, as well as hormonal responses. We further show that BRD1/2/13 represent unique subunits of the
BRM complexes, and their depletion severely affects the integrity of the complex, resulting in the formation of residual assemblies. Finally, analyses of BRM complexes after proteasome inhibition revealed the existence of a module consisting of the ATPase, ARP, and BDH proteins, assembled with other subunits in a BRD-dependent manner. Together, our results suggest modular organization of plant SWI/SNF complexes and provide a biochemical explanation for mutant phenotypes.