Dynamics of the HP1 Hinge Region with DNA Measured by Site-Directed Spin Labeling-EPR Spectroscopy
Dynamics of the HP1 Hinge Region with DNA Measured by Site-Directed Spin Labeling-EPR Spectroscopy
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DOI：
10.1007/s00723-022-01519-2
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发表时间：
2023-01-05
影响因子：
1
通讯作者：
Arata，Toshiaki
中科院分区：
文献类型：
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作者：
Suetake，Isao;Sato，Kazunobu;Arata，Toshiaki
异染色质蛋白1（HP 1）是一种表观遗传学的阅读器，它具有两个保守的结构域：染色阴影结构域（CSD）和染色结构域（CD）。CD和CSD通过铰链区（HR）连接。N、C尾和HR估计是无序的。在50%甘油中，来自无序区域侧链自旋标记的EPR光谱被分解为两个运动部分或纳秒到较慢的时间尺度;然而，较慢动力学的部分被标记为具有位点特异性。HR（中间区域）的缓慢部分被单体突变消除，并在二聚体状态下被N-尾截短减少。在HR内，通过截短C-尾，HR中C-末端区域的动力学缓慢部分减少。此外，通过截短N-尾-CD-HR，C-尾中基底区而不是C-尾末端的动力学的缓慢部分显著降低。总之，HR的中间区域通过与N-尾的直接或间接相互作用而松散地组织，从一个单体施加到另一个单体，并且HR中的C-末端区域在自抑制状态下接触单体内的C-尾，就像我推测的那样。令人惊讶的是，DNA不影响光谱，无论甘油的添加，而它明显限制了CD和CSD在HP 1 α，三个旁系同源物之一。相反，DNA对另一种parenchymal HP 1 γ中检测的所有区域的动力学没有显示出显著的影响。我们提出，由于作为HR的模糊复合物的滑动，HP 1 α经历非常快速的扩散，并且CD和CSD以类似的动力学围绕DNA被束缚，这与报道的分子动力学模拟一致[Watanabeet al.， Biophys. J.114：2336-2352，2018]。
An epigenetic reader, heterochromatin protein 1 (HP1), possesses two conserved domains, the chromoshadow domain (CSD) and chromodomain (CD). The CD and CSD are connected by the hinge region (HR). N, C-tails and HR are estimated to be disordered. In 50% glycerol, EPR spectra from side-chain spin labels of the disordered regions were resolved into two motional fractions or nanoseconds to slower timescales; however, the fraction of slower dynamics was labeled to be site-specific. The slow fraction of the HR (middle region) was abolished by monomer mutation and reduced by N-tail truncation in the dimer state. Within the HR, by truncation of the C-tail, the slow fraction of dynamics of the C-terminal region in the HR were reduced. In addition, the slow fraction of dynamics of the basal region in the C-tail, but not the C-tail end, was significantly reduced by truncating the N-tail-CD-HR. Together, the middle region of the HR was loosely organized by direct or indirect interaction with the N-tail, exerted from one monomer to the other, and the C-terminal region in the HR contacted the C-tail within a monomer in an autoinhibited state, as presumably proposed. Surprisingly, DNA did not affect the spectra, irrespective of glycerol addition, while it clearly restricted the CD and the CSD in HP1α, one of three paralogs. In contrast, DNA did not show a significant effect on the dynamics of all regions examined in another paralog HP1γ. We propose that HP1α undergoes very rapid diffusion due to sliding as a fuzzy complex of the HR and that CD and CSD are tethered with similar dynamics around DNA, which is in agreement with reported molecular dynamics simulations [Watanabeet al., Biophys. J.114: 2336–2352, 2018].