Mutational analysis of the stability of the H2A and H2B histone monomers.
Mutational analysis of the stability of the H2A and H2B histone monomers.
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H2A 和 H2B 组蛋白单体稳定性的突变分析。
DOI：
10.1016/j.jmb.2008.10.040
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发表时间：
2008
影响因子：
5.6
通讯作者：
Gloss,LisaM
中科院分区：
文献类型：
--
作者：
Stump,MatthewR;Gloss,LisaM
真核组蛋白异源二聚体H2 A-H2 B通过一个强制性的二聚体中间体折叠，该中间体在停流死时间中在几乎扩散限制的缔合反应中形成。尚不清楚在缔合之前是否存在分离的单体的部分折叠。为了解决单体中结构对快速缔合的可能贡献，我们在不存在其异二聚体伴侣的情况下表征了H2 A和H2 B单体。通过远紫外圆二色性，H2 A和H2 B单体分别为15%和31%的螺旋，显着小于在X射线晶体结构中观察到的。固有Tyr荧光的丙烯酰胺淬灭指示三级结构。H2 A和H2 B单体的解折叠自由能分别为2.5和2.9 kcal mol−1;在10 μM浓度下，单体的稳定性总和为天然二聚体稳定性的约60%。螺旋含量、稳定性和m值表明H2 B具有比H2 A更稳定、更紧凑的结构。单体m值大于扩展组蛋白折叠基序的预期值，表明单体采用过度塌陷的结构。停流再折叠开始从脲变性单体或部分折叠的单体填充在低变性剂浓度产生基本相同的速率，表明单体折叠是生产性的快速协会和折叠的异二聚体。在H2 A和H2 B中引入一系列Ala和Gly突变，以探测螺旋倾向对单体结构和稳定性的重要性。突变研究表明，组蛋白折叠的中心α-螺旋，使广泛的单体间接触，在H2 B中是结构化的，但在H2 A中仅部分折叠。
The eukaryotic histone heterodimer H2A–H2B folds through an obligatory dimeric intermediate that forms in a nearly diffusion-limited association reaction in the stopped-flow dead time. It is unclear whether there is partial folding of the isolated monomers before association. To address the possible contributions of structure in the monomers to the rapid association, we characterized H2A and H2B monomers in the absence of their heterodimeric partner. By far-UV circular dichroism, the H2A and H2B monomers are 15% and 31% helical, respectively—significantly less than observed in X-ray crystal structures. Acrylamide quenching of the intrinsic Tyr fluorescence was indicative of tertiary structure. The H2A and H2B monomers exhibit free energies of unfolding of 2.5 and 2.9 kcal mol−1, respectively; at 10 μM, the sum of the stability of the monomers is ∼60% of the stability of the native dimer. The helical content, stability, and m values indicate that H2B has a more stable, compact structure than H2A. The monomer m values are larger than expected for the extended histone fold motif, suggesting that the monomers adopt an overly collapsed structure. Stopped-flow refolding—initiated from urea-denatured monomers or the partially folded monomers populated at low denaturant concentrations—yielded essentially identical rates, indicating that monomer folding is productive in the rapid association and folding of the heterodimer. A series of Ala and Gly mutations were introduced into H2A and H2B to probe the importance of helix propensity on the structure and stability of the monomers. The mutational studies show that the central α-helix of the histone fold, which makes extensive intermonomer contacts, is structured in H2B but only partially folded in H2A.
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作者：
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通讯作者：
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H2A-H2B 组蛋白的 N 末端尾部影响二聚体结构和稳定性。
影响因子：
2.9
作者：
B. Placek;L. Gloss
通讯作者：
L. Gloss
影响因子：
2.9
作者：
ZITZEWITZ, JA;BILSEL, O;MATTHEWS, CR
通讯作者：
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DOI：
10.1021/bi973171y
发表时间：
1998
期刊：
Biochemistry.
影响因子：
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作者：
Shao,X;Matthews,CR
通讯作者：
Matthews,CR
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影响因子：
2.9
作者：
Derrick W. Meinhold;Sarah A. Boswell;W. Colón
通讯作者：
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