Zhao Tianyue, Gomez Florian A, David Cassandra T, Rootes Christina L, Stewart Cameron R, Moseley Gregory W, Rawlinson Stephen M
Department of Microbiology, Biomedicine Discovery Institute, Monash University, 19 Innovation Walk, Clayton Campus, Clayton, VIC 3800, Australia.
Commonwealth Scientific and Industrial Research Organisation (CSIRO), Health and Biosecurity, Australian Centre for Disease Preparedness, Geelong, VIC 3219, Australia.
Viruses. 2025 May 30;17(6):797. doi: 10.3390/v17060797.
Hendra virus (HeV) is a highly pathogenic member of the genus (family , order ), for which all basic replication processes are located in the cytoplasm. The HeV matrix (M) protein plays essential roles in viral assembly and budding at the plasma membrane, but also undergoes dynamic nuclear and nucleolar trafficking, accumulating in nucleoli early in infection, before relocalising to the plasma membrane. We previously showed that M targets sub-nucleolar compartments-the fibrillar centre (FC) and dense fibrillar component (DFC)-to modulate rRNA biogenesis by mimicking a process occurring during a nucleolar DNA-damage response (DDR). Here, we show that M protein sub-nucleolar localisation is regulated by ubiquitination, which controls its redistribution between the FC-DFC and granular component (GC). The mutagenesis of a conserved lysine (K258) reported to undergo ubiquitination, combined with the pharmacological modulation of ubiquitination, indicated that a positive charge at K258 is required for M localisation to the FC-DFC, while ubiquitination regulates subsequent egress from the FC-DFC to the GC. M proteins from multiple exhibited similar ubiquitin-dependent sub-nucleolar trafficking, indicating a conserved mechanism. These findings reveal a novel mechanism regulating viral protein transport between phase-separated sub-nucleolar compartments and highlight ubiquitination as a key modulator of intra-nucleolar trafficking.
亨德拉病毒（HeV）是（科、目）属的一种高致病性病毒，其所有基本复制过程均发生在细胞质中。HeV基质（M）蛋白在病毒装配和质膜出芽过程中发挥着重要作用，但也会经历动态的核内和核仁运输，在感染早期积聚在核仁中，然后重新定位到质膜。我们之前表明，M靶向核仁亚区室——纤维中心（FC）和致密纤维成分（DFC）——通过模拟核仁DNA损伤反应（DDR）过程中发生的一个过程来调节rRNA生物合成。在这里，我们表明M蛋白的核仁亚区室定位受泛素化调节，泛素化控制其在FC-DFC和颗粒成分（GC）之间的重新分布。据报道，一个保守赖氨酸（K258）发生泛素化，对其进行诱变，并结合泛素化的药理学调节，表明K258处的正电荷是M定位于FC-DFC所必需的，而泛素化调节随后从FC-DFC向GC的流出。来自多个（物种）的M蛋白表现出类似的泛素依赖性核仁亚区室运输，表明存在一种保守机制。这些发现揭示了一种调节病毒蛋白在相分离的核仁亚区室之间运输的新机制，并突出了泛素化作为核仁内运输的关键调节因子的作用。
