Deckert Jutta, Struhl Kevin
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA.
Mol Cell Biol. 2002 Sep;22(18):6458-70. doi: 10.1128/MCB.22.18.6458-6470.2002.
Certain DNA-binding repressors inhibit transcription by recruiting Rpd3 histone deacetylase complexes to promoters and generating domains of histone deacetylation that extend over a limited number of nucleosomes. Here, we show that the degree of Rpd3-dependent repression depends on the activator and the level of activation, not the extent of histone deacetylation. In all cases tested, activator binding is unaffected by histone deacetylation. In contrast, Rpd3-dependent repression is associated with decreased occupancy by TATA binding protein (TBP), the Swi/Snf nucleosome-remodeling complex, and the SAGA histone acetylase complex. Transcriptional repression is bypassed by direct recruitment of TBP and several TBP-associated factors, but not by natural activation domains or direct recruitment of polymerase II holoenzyme components. These results suggest that the domain of localized histone deacetylation generated by recruitment of Rpd3 mediates repression by inhibiting recruitment of chromatin-modifying activities and TBP.
某些DNA结合阻遏物通过将Rpd3组蛋白去乙酰化酶复合物募集到启动子上并产生延伸至有限数量核小体的组蛋白去乙酰化结构域来抑制转录。在此,我们表明Rpd3依赖性阻遏的程度取决于激活因子和激活水平,而非组蛋白去乙酰化的程度。在所有测试的情况下,激活因子结合不受组蛋白去乙酰化的影响。相反,Rpd3依赖性阻遏与TATA结合蛋白(TBP)、Swi/Snf核小体重塑复合物和SAGA组蛋白乙酰化酶复合物的占有率降低有关。通过直接募集TBP和几种与TBP相关的因子可绕过转录阻遏,但自然激活结构域或直接募集聚合酶II全酶组分则不能。这些结果表明,通过募集Rpd3产生的局部组蛋白去乙酰化结构域通过抑制染色质修饰活性和TBP的募集来介导阻遏。