The intrinsic stability of H2B-ubiquitylated nucleosomes and their in vitro assembly/disassembly by histone chaperone NAP1
The intrinsic stability of H2B-ubiquitylated nucleosomes and their in vitro assembly/disassembly by histone chaperone NAP1
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DOI：
10.1016/j.bbagen.2019.129497
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发表时间：
2020-03-01
影响因子：
3
通讯作者：
Krajewski, Wladyslaw A.
中科院分区：
文献类型：
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作者：
Krajewski, Wladyslaw A.
背景：除了作为组蛋白“读卡器”对接位点的基因调控功能外，一些组蛋白修饰可以直接影响核小体的结构。MOF-MSL复合物沉积的h2bk34泛素化增加了体外核小体动力学，促进了H2A/H2B二聚体向组蛋白受体的捐赠。方法：在存在或不存在组蛋白受体的“生理”离子条件下，我们评估了h2bk34泛素化核小体的温度依赖性稳定性，并通过重组小鼠NAP1检测了泛素化核小体的体外组装和拆卸。结果：H2BK34ub修饰足以促进仅一种H2A/H2B二聚体的选择性排出，而不依赖于组蛋白结合剂。尽管mNAP1与H2BK34ub（但不是未经修饰的）核小体具有强大的H2A/H2B二聚体位移效应，但在体外生理条件下，NAP1可以对称或不对称地组装泛素化核小体。结论和一般意义：一个核小体H2A/H2B二聚体的流动性增加是具有核小体内碱基的H2BK34泛素化固有的核小体不稳定特性。NAP合理有效地组装h2bk34泛素化核小体的能力假设了H2BK34ub标记以MOF-MSL独立方式沉积/分布的潜在机制（例如，在转录延伸时组蛋白二聚体交换期间）。
Background: Apart the gene-regulatory functions as docking sites for histone 'readers', some histone modifications could directly affect nucleosome structure. The H2BK34-ubiquitylation deposited by MOF-MSL complex, increases nucleosome dynamics in vitro and promotes donation of one H2A/H2B dimer to histone acceptors.Methods: We evaluated temperature-depended stability of H2BK34-ubiquitylated nucleosomes under 'physiological' ionic conditions in the presence or absence of histone acceptor, and examined assembly and disassembly of ubiquitylated nucleosomes in vitro by recombinant mouse NAP1.Results: H2BK34ub modification is sufficient to promote selective eviction of only one H2A/H2B dimer independently of histone-binding agents. Despite the robust H2A/H2B dimer-displacement effect of mNAP1 with the H2BK34ub (but not unmodified) nucleosomes, NAP1 could assemble symmetrically- or asymmetrically ubiquitylated nucleosomes under 'physiological' conditions in vitro.Conclusions and general significance: The increased mobility of one nucleosomal H2A/H2B dimer is an intrinsic nucleosome destabilizing property of H2BK34 ubiquitylation that has the intranucleosome bases. The ability of NAP to reasonably efficiently assemble H2BK34-ubiquitylated nucleosomes supposes a potential mechanism for deposition/distribution of H2BK34ub mark in the MOF-MSL independent manner (for example, during histone dimer exchange upon transcription elongation).