Peng Qiu, Wang Lujuan, Qin Zailong, Wang Jia, Zheng Xiang, Wei Lingyu, Zhang Xiaoyue, Zhang Xuemei, Liu Can, Li Zhengshuo, Wu Yangge, Li Guiyuan, Yan Qun, Ma Jian
Department of Clinical Laboratory, Xiangya Hospital, Central South University, Changsha, China.
Cancer Research Institute, School of Basic Medical Science, Central South University, Changsha, China.
J Virol. 2020 Mar 17;94(7). doi: 10.1128/JVI.01771-19.
Biological macromolecule condensates formed by liquid-liquid phase separation (LLPS) have been discovered in recent years to be prevalent in biology. These condensates are involved in diverse processes, including the regulation of gene expression. LLPS of proteins have been found in animal, plant, and bacterial species but have scarcely been identified in viral proteins. Here, we discovered that Epstein-Barr virus (EBV) EBNA2 and EBNALP form nuclear puncta that exhibit properties of liquid-like condensates (or droplets), which are enriched in superenhancers of MYC and Runx3. EBNA2 and EBNALP are transcription factors, and the expression of their target genes is suppressed by chemicals that perturb LLPS. Intrinsically disordered regions (IDRs) of EBNA2 and EBNALP can form phase-separated droplets, and specific proline residues of EBNA2 and EBNALP contribute to droplet formation. These findings offer a foundation for understanding the mechanism by which LLPS, previously determined to be related to the organization of P bodies, membraneless organelles, nucleolus homeostasis, and cell signaling, plays a key role in EBV-host interactions and is involved in regulating host gene expression. This work suggests a novel anti-EBV strategy where developing appropriate drugs of interfering LLPS can be used to destroy the function of the EBV's transcription factors. Protein condensates can be assembled via liquid-liquid phase separation (LLPS), a process involving the concentration of molecules in a confined liquid-like compartment. LLPS allows for the compartmentalization and sequestration of materials and can be harnessed as a sensitive strategy for responding to small changes in the environment. This study identified the Epstein-Barr virus (EBV) proteins EBNA2 and EBNALP, which mediate virus and cellular gene transcription, as transcription factors that can form liquid-like condensates at superenhancer sites of MYC and Runx3. This study discovered the first identified LLPS of EBV proteins and emphasized the importance of LLPS in controlling host gene expression.
近年来发现,由液-液相分离(LLPS)形成的生物大分子凝聚物在生物学中普遍存在。这些凝聚物参与多种过程,包括基因表达的调控。蛋白质的液-液相分离已在动物、植物和细菌物种中被发现,但在病毒蛋白中却鲜有报道。在此,我们发现爱泼斯坦-巴尔病毒(EBV)的EBNA2和EBNALP形成核斑点,表现出类似液体凝聚物(或液滴)的特性,这些凝聚物富含MYC和Runx3的超级增强子。EBNA2和EBNALP是转录因子,其靶基因的表达受到干扰液-液相分离的化学物质的抑制。EBNA2和EBNALP的内在无序区域(IDR)可形成相分离液滴,且EBNA2和EBNALP的特定脯氨酸残基有助于液滴形成。这些发现为理解液-液相分离在EBV-宿主相互作用中发挥关键作用并参与调控宿主基因表达的机制奠定了基础,此前已确定液-液相分离与P体、无膜细胞器、核仁稳态及细胞信号传导的组织有关。这项工作提出了一种新的抗EBV策略,即开发合适的干扰液-液相分离的药物可用于破坏EBV转录因子的功能。蛋白质凝聚物可通过液-液相分离(LLPS)组装而成,这一过程涉及分子在受限的类似液体的隔室内浓缩。液-液相分离允许物质的区室化和隔离,并可作为一种对环境微小变化做出反应的敏感策略加以利用。本研究确定了介导病毒和细胞基因转录的爱泼斯坦-巴尔病毒(EBV)蛋白EBNA2和EBNALP,它们是能够在MYC和Runx3的超级增强子位点形成类似液体凝聚物的转录因子。本研究发现了首个被鉴定的EBV蛋白的液-液相分离现象,并强调了液-液相分离在控制宿主基因表达中的重要性。