The Integrity of the YxxL Motif of Ebola Virus VP24 Is Important for the Transport of Nucleocapsid-Like Structures and for the Regulation of Viral RNA Synthesis.
The Integrity of the YxxL Motif of Ebola Virus VP24 Is Important for the Transport of Nucleocapsid-Like Structures and for the Regulation of Viral RNA Synthesis.
复制标题
埃博拉病毒 VP24 的 YxxL 基序的完整性对于核衣壳样结构的运输和病毒 RNA 合成的调节非常重要。
作者：
Takamatsu Y;Kolesnikova L;Schauflinger M;Noda T;Becker S.
虽然病毒基质蛋白中的晚期结构域对于介导有效的病毒出芽是至关重要的，但对病毒核衣壳蛋白中晚期结构域的作用知之甚少。在这里，我们的特点是在埃博拉病毒核衣壳蛋白VP24的潜在的后期域功能的YxxL基序的功能相关性。YxxL基序的突变对VP24的功能有两种相反的影响。一方面，该突变影响了VP24在病毒RNA转录和复制中的调节功能，这与微基因组掺入释放的具有转录和复制能力的病毒样颗粒（trVLPs）的增加相关。因此，用这些trVLPs感染的细胞显示出更高水平的病毒转录。另一方面，YxxL基序的突变极大地损害了由病毒蛋白NP、VP35和VP24组成的核衣壳样结构（NCLS）的细胞内转运以及释放的trVLPs的长度。拯救表达YxxL缺陷型VP24的重组埃博拉病毒的尝试失败了，强调了这种基序对病毒生命周期的重要性。重要的是埃博拉病毒（EBOV）引起严重的发热，病死率高，到目前为止，还没有可用的特异性治疗。了解病毒和宿主蛋白之间的相互作用对于确定新的治疗方法非常重要。VP24是一种重要的核衣壳组分，是调节病毒RNA合成和在病毒核衣壳转运到质膜之前浓缩病毒核衣壳所必需的。我们对VP24中YxxL基序的功能分析表明，它作为核帽样结构（NCLSs）和细胞蛋白质之间的界面，以Alix非依赖性方式促进NCLSs的细胞内转运。此外，YxxL基序对于VP24在病毒RNA合成中的抑制功能是必需的。未能拯救编码具有突变的YxxL基序的VP24的EBOV表明YxxL基序的完整性对于EBOV生长是必需的。因此，该基序可能代表抗病毒干扰的潜在靶点。
While it is well appreciated that late domains in the viral matrix proteins are crucial to mediate efficient virus budding, little is known about roles of late domains in the viral nucleocapsid proteins. Here, we characterized the functional relevance of a YxxL motif with potential late-domain function in the Ebola virus nucleocapsid protein VP24. Mutations in the YxxL motif had two opposing effects on the functions of VP24. On the one hand, the mutation affected the regulatory function of VP24 in viral RNA transcription and replication, which correlated with an increased incorporation of minigenomes into released transcription- and replication-competent virus-like particles (trVLPs). Consequently, cells infected with those trVLPs showed higher levels of viral transcription. On the other hand, mutations of the YxxL motif greatly impaired the intracellular transport of nucleocapsid-like structures (NCLSs) composed of the viral proteins NP, VP35, and VP24 and the length of released trVLPs. Attempts to rescue recombinant Ebola virus expressing YxxL-deficient VP24 failed, underlining the importance of this motif for the viral life cycle.IMPORTANCEEbola virus (EBOV) causes a severe fever with high case fatality rates and, so far, no available specific therapy. Understanding the interplay between viral and host proteins is important to identify new therapeutic approaches. VP24 is one of the essential nucleocapsid components and is necessary to regulate viral RNA synthesis and condense viral nucleocapsids before their transport to the plasma membrane. Our functional analyses of the YxxL motif in VP24 suggested that it serves as an interface between nucleocapsid-like structures (NCLSs) and cellular proteins, promoting intracellular transport of NCLSs in an Alix-independent manner. Moreover, the YxxL motif is necessary for the inhibitory function of VP24 in viral RNA synthesis. A failure to rescue EBOV encoding VP24 with a mutated YxxL motif indicated that the integrity of the YxxL motif is essential for EBOV growth. Thus, this motif might represent a potential target for antiviral interference.