Zhao K, Käs E, Gonzalez E, Laemmli U K
Department of Molecular Biology and Biochemistry, University of Geneva, Switzerland.
EMBO J. 1993 Aug;12(8):3237-47. doi: 10.1002/j.1460-2075.1993.tb05993.x.
An experimental assay was developed to search for proteins capable of antagonizing histone H1-mediated general repression of transcription. T7 RNA polymerase templates containing an upstream scaffold-associated region (SAR) were highly selectively repressed by H1 relative to non-SAR control templates. This is due to the nucleation of H1 assembly into flanking DNA brought about by the numerous A-tracts (AT-rich sequences containing short homopolymeric runs of dA.dT base pairs) of the SAR. Partial, selective titration of these A-tracts by the high mobility group (HMG) protein HMG-I/Y led to the complete derepression of transcription from the SAR template by inducing the redistribution of H1 on to non-SAR templates. SARs are associated with many highly transcribed regulated genes where they may serve to facilitate the HMG-I/Y-mediated displacement of histone H1 in chromatin. Indeed, HMG-I/Y was found to be strongly enriched in the H1-depleted subfraction which can be isolated from chromatin.
开发了一种实验测定法来寻找能够拮抗组蛋白H1介导的转录全面抑制作用的蛋白质。相对于非支架附着区域（SAR）对照模板，含有上游SAR的T7 RNA聚合酶模板被H1高度选择性地抑制。这是由于SAR的大量A序列（富含AT的序列，包含短的同聚dA·dT碱基对）导致H1组装成侧翼DNA的成核作用。高迁移率族（HMG）蛋白HMG-I/Y对这些A序列进行部分、选择性滴定，通过诱导H1重新分布到非SAR模板上，导致SAR模板的转录完全去抑制。SAR与许多高度转录的调控基因相关，在这些基因中它们可能有助于HMG-I/Y介导的染色质中组蛋白H1的置换。实际上，发现HMG-I/Y在可从染色质中分离出的H1缺失亚组分中高度富集。
