Chaetocin disrupts the SUV39H1–HP1 interaction independent of SUV39H1 methyltransferase activity
Chaetocin disrupts the SUV39H1–HP1 interaction independent of SUV39H1 methyltransferase activity
复制标题
毛壳素破坏 SUV39H1–HP1 相互作用，与 SUV39H1 甲基转移酶活性无关
DOI：
10.1042/bcj20220528
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发表时间：
2023
影响因子：
4.1
通讯作者：
Keung, Albert J.
中科院分区：
文献类型：
--
作者：
Han, Linna;Lee, Jessica B.;Indermaur, Elaine W.;Keung, Albert J.
控制染色质组分的活性和相互作用的化学工具对我们对细胞和疾病过程的理解有广泛的影响。准确识别它们的分子效应对临床工作和科学研究的解释是很重要的。催产素是一种广泛使用的化学物质，可以降低细胞中H3K9的甲基化。它通常被认为是SUV39H1/SU(VAR) 3-9组蛋白甲基转移酶活性的特异性抑制剂，尽管先前的观察表明，催产素可能通过共价机制抑制甲基转移酶活性，包括其聚硫二硫嘧啶“弹头”功能。在科学研究中持续使用催产素可能源于H3K9甲基化降低的净效应，无论其直接或间接机制如何。然而，除了抑制H3K9甲基化水平外，催产素对SUV39H1可能还有其他分子影响，这可能会混淆过去和未来实验研究的解释。在这里，我们验证了一个新的假设，即催产素除了抑制甲基转移酶活性外，还可能对下游产生额外的影响。通过截断突变体、酵母双杂交系统和定向玻璃结合实验，我们发现人类SUV39H1色域（CD）和HP1色影域（CSD）直接相互作用。chaeoxytocin通过其二硫功能与SUV39H1的CD共价结合抑制这种结合作用，并具有一定的特异性，而组蛋白H3-HP1的相互作用不受抑制。考虑到HP1二聚体在驱动反馈级联招募SUV39H1和建立和稳定组成型异染色质中的关键作用，应该广泛考虑催产素的这种额外的分子后果。
Chemical tools to control the activities and interactions of chromatin components have broad impact on our understanding of cellular and disease processes. It is important to accurately identify their molecular effects to inform clinical efforts and interpretations of scientific studies. Chaetocin is a widely used chemical that decreases H3K9 methylation in cells. It is frequently attributed as a specific inhibitor of the histone methyltransferase activities of SUV39H1/SU(VAR)3–9, although prior observations showed chaetocin likely inhibits methyltransferase activity through covalent mechanisms involving its epipolythiodixopiperazine disulfide ‘warhead’ functionality. The continued use of chaetocin in scientific studies may derive from the net effect of reduced H3K9 methylation, irrespective of a direct or indirect mechanism. However, there may be other molecular impacts of chaetocin on SUV39H1 besides inhibition of H3K9 methylation levels that could confound the interpretation of past and future experimental studies. Here, we test a new hypothesis that chaetocin may have an additional downstream impact aside from inhibition of methyltransferase activity. Using a combination of truncation mutants, a yeast two-hybrid system, and directin vitrobinding assays, we show that the human SUV39H1 chromodomain (CD) and HP1 chromoshadow domain (CSD) directly interact. Chaetocin inhibits this binding interaction through its disulfide functionality with some specificity by covalently binding with the CD of SUV39H1, whereas the histone H3–HP1 interaction is not inhibited. Given the key role of HP1 dimers in driving a feedback cascade to recruit SUV39H1 and to establish and stabilize constitutive heterochromatin, this additional molecular consequence of chaetocin should be broadly considered.