Revisiting the role of PML protein targeting and disruption of PML bodies in human cytomegalovirus infection
Revisiting the role of PML protein targeting and disruption of PML bodies in human cytomegalovirus infection
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重新审视 PML 蛋白靶向和 PML 体破坏在人类巨细胞病毒感染中的作用
DOI：
10.1099/acmi.ac2020.po0734
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发表时间：
2020
影响因子：
--
通讯作者：
Paulus C
中科院分区：
文献类型：
--
作者：
Paulus C
早幼粒细胞白血病（PML）体是一种核细胞器，参与小泛素样修饰蛋白（SUMO）的翻译后修饰和抗病毒宿主细胞对感染的反应。72-kDa立即早期蛋白1（IE 1）被认为是由人类巨细胞病毒（8种人类疱疹病毒之一）编码的PML小体的主要拮抗剂。以前的工作表明，IE 1和PML蛋白，PML机构的中央组织者之间的相互作用，并随后中断这些细胞器在病毒复制中起着关键作用，通过抵消内在的抗病毒免疫和干扰素（IFN）刺激基因的诱导。然而，这幅图主要来自于研究已知或预测为全局错误折叠和代谢不稳定的突变IE 1蛋白。我们通过成簇电荷-丙氨酸扫描系统地筛选稳定的IE 1突变体。我们发现了一种选择性缺陷PML相互作用的突变蛋白（IE 1cc 172 -176）。突变体和野生型蛋白质之间的功能比较显示，IE 1可以通过混合聚合SUMO链进行修饰，并且它通过不同的机制靶向PML和Sp100，这两种主要成分的PML机构。出乎意料的是，IE 1cc 172 -176几乎与野生型IE 1一样有效地支持病毒复制。此外，与野生型蛋白质和病毒相比，在突变体中观察到肿瘤坏死因子α、IFN-β、IFN-λ和IFN刺激的基因表达水平较低，而不是较高（如预期）。这些结果表明，PML小体的破坏与抗病毒基因表达的诱导而非抑制有关。我们的研究结果挑战了目前关于PML小体在病毒感染中的作用的观点。
Promyelocytic leukaemia (PML) bodies are nuclear organelles implicated in post-translational modification by small ubiquitin-like modifier (SUMO) proteins and in the antiviral host cell response to infection. The 72-kDa immediate-early protein 1 (IE1) is considered the principal antagonist of PML bodies encoded by the human cytomegalovirus, one of eight human herpesviruses. Previous work has suggested that the interaction between IE1 and PML proteins, the central organisers of PML bodies, and the subsequent disruption of these organelles serve a critical role in viral replication by counteracting intrinsic antiviral immunity and the induction of interferon (IFN)-stimulated genes. However, this picture has emerged largely from studying mutant IE1 proteins known or predicted to be globally misfolded und metabolically unstable. We systematically screened for stable IE1 mutants by clustered charge-to-alanine scanning. We identified a mutant protein (IE1cc172-176) selectively defective for PML interaction. Functional comparisons between the mutant and wild-type protein revealed that IE1 can undergo modification by mixed polymeric SUMO chains and that it targets PML and Sp100, the two main constituents of PML bodies, via distinct mechanisms. Unexpectedly, IE1cc172-176 supported viral replication almost as efficiently as wild-type IE1. Moreover, lower instead of higher (as expected) levels of tumor necrosis factor alpha, IFN-beta, IFN-lambda and IFN-stimulated gene expression were observed with the mutant compared to the wild-type protein and virus. These results suggest that the disruption of PML bodies is linked to induction rather than inhibition of antiviral gene expression. Our findings challenge current views regarding the role of PML bodies in viral infection.