Ling X, Harkness T A, Schultz M C, Fisher-Adams G, Grunstein M
Department of Biological Chemistry, University of California at Los Angeles (UCLA) School of Medicine, 90095, USA.
Genes Dev. 1996 Mar 15;10(6):686-99. doi: 10.1101/gad.10.6.686.
The hydrophilic amino-terminal sequences of histones H3 and H4 extend from the highly structured nucleosome core. Here we examine the importance of the amino termini and their position in the nucleosome with regard to both nucleosome assembly and gene regulation. Despite previous conclusions based on nonphysiological nucleosome reconstitution experiments, we find that the histone amino termini are important for nucleosome assembly in vivo and in vitro. Deletion of both tails, a lethal event, alters micrococcal nuclease-generated nucleosomal ladders, plasmid superhelicity in whole cells, and nucleosome assembly in cell extracts. The H3 and H4 amino-terminal tails have redundant functions in this regard because the presence of either tail allows assembly and cellular viability. Moreover, the tails need not be attached to their native carboxy-terminal core. Their exchange re-establishes both cellular viability and nucleosome assembly. In contrast, the regulation of GAL1 and the silent mating loci by the H3 and H4 tails is highly disrupted by exchange of the histone amino termini.
组蛋白H3和H4的亲水性氨基末端序列从高度结构化的核小体核心延伸出来。在此，我们研究了氨基末端及其在核小体中的位置对于核小体组装和基因调控的重要性。尽管之前基于非生理性核小体重构实验得出了一些结论，但我们发现组蛋白氨基末端在体内和体外的核小体组装中都很重要。删除两条尾巴是一个致死事件，它会改变微球菌核酸酶产生的核小体条带、全细胞中的质粒超螺旋以及细胞提取物中的核小体组装。在这方面，H3和H4氨基末端尾巴具有冗余功能，因为任何一条尾巴的存在都能允许组装并维持细胞活力。此外，尾巴无需连接到其天然的羧基末端核心。它们的交换能重新建立细胞活力和核小体组装。相比之下，H3和H4尾巴对GAL1和沉默交配位点的调控会因组蛋白氨基末端的交换而受到严重破坏。
