Charge-neutralization effect of the tail regions on the histone H2A/H2B dimer structure.
Charge-neutralization effect of the tail regions on the histone H2A/H2B dimer structure.
复制标题
尾部区域对组蛋白 H2A/H2B 二聚体结构的电荷中和作用。
作者：
Saikusa;K.;Shimoyama;S.;Asano;Y.;Nagadoi;A.;Sato;M.;Kurumizaka;H.;Nishimura;Y.;and Akashi;S.
众所周知，组蛋白尾部的各种修饰在转录起始的调控中起着重要作用。在本研究中，在组蛋白H2A/H2B二聚体中，一些赖氨酸（Lys）和精氨酸（Arg）残基分别被乙酰化和去亚胺化，并通过天然质谱法研究了电荷中和对二聚体结构的影响。考虑到乙酰化和去亚胺化都能中和碱性氨基酸残基的正电荷，我们预计这些修饰会相应影响组蛋白H2A/H2B二聚体的气相行为。与这一预期相反，发现精氨酸的消旋导致二聚体气相碰撞解离的难度更大，而赖氨酸残基的乙酰化并没有引起二聚体稳定性的剧烈变化。相比之下，离子迁移率-质谱（IM - MS）实验表明，乙酰化和去甲基化二聚体离子到达迁移细胞的时间与未修饰的二聚体离子相比变化很小，这表明二聚体离子的大小没有被修饰改变。碱度高于赖氨酸的Arg的电荷中和可能引发了一些在IM - MS中无法发现的二聚体结构的变化，但可以通过气相碰撞检测到。
It is well known that various modifications of histone tails play important roles in the regulation of transcription initiation. In this study, some lysine (Lys) and arginine (Arg) residues were acetylated and deiminated, respectively, in the histone H2A/H2B dimer, and charge‐neutralization effects on the dimer structure were studied by native mass spectrometry. Given that both acetylation and deimination neutralize the positive charges of basic amino acid residues, it had been expected that these modifications would correspondingly affect the gas‐phase behavior of the histone H2A/H2B dimer. Contrary to this expectation, it was found that Arg deimination led to greater difficulty of dissociation of the dimer by gas‐phase collision, whereas acetylation of Lys residues did not cause such a drastic change in the dimer stability. In contrast, ion mobility‐mass spectrometry (IM‐MS) experiments showed that arrival times in the mobility cell both of acetylated and of deiminated dimer ions changed little from those of the unmodified dimer ions, indicating that the sizes of the dimer ions did not change by modification. Charge neutralization of Arg, basicity of which is higher than Lys, might have triggered some alteration of the dimer structure that cannot be found in IM‐MS but can be detected by collision in the gas phase.