Cao Jingjing, Lin Cui, Wang Huijuan, Wang Lun, Zhou Niu, Jin Yulan, Liao Min, Zhou Jiyong
Key Laboratory of Animal Virology of Ministry of Agriculture, Zhejiang University, Hangzhou, People's Republic of China.
Key Laboratory of Animal Virology of Ministry of Agriculture, Zhejiang University, Hangzhou, People's Republic of China Institute of Infection & Immunity, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, People's Republic of China
J Virol. 2015 Mar;89(5):2777-91. doi: 10.1128/JVI.03117-14. Epub 2014 Dec 24.
Microtubule transport of circovirus from the periphery of the cell to the nucleus is essential for viral replication in early infection. How the microtubule is recruited to the viral cargo remains unclear. In this study, we observed that circovirus trafficking is dependent on microtubule polymerization and that incoming circovirus particles colocalize with cytoplasmic dynein and endosomes. However, circovirus binding to dynein was independent of the presence of microtubular α-tubulin and translocation of cytoplasmic dynein into the nucleus. The circovirus capsid (Cap) subunit enhanced microtubular acetylation and directly interacted with intermediate chain 1 (IC1) of dynein. N-terminal residues 42 to 100 of the Cap viral protein were required for efficient binding to the dynein IC1 subunit and for retrograde transport. Knockdown of IC1 decreased virus transport and replication. These results demonstrate that Cap is a direct ligand of the cytoplasmic dynein IC1 subunit and an inducer of microtubule α-tubulin acetylation. Furthermore, Cap recruits the host dynein/microtubule machinery to facilitate transport toward the nucleus by an endosomal mechanism distinct from that used for physiological dynein cargo.
Incoming viral particles hijack the intracellular trafficking machinery of the host in order to migrate from the cell surface to the replication sites. Better knowledge of the interaction between viruses and virus proteins and the intracellular trafficking machinery may provide new targets for antiviral therapies. Currently, little is known about the molecular mechanisms of circovirus transport. Here, we report that circovirus particles enter early endosomes and utilize the microtubule-associated molecular motor dynein to travel along microtubules. The circovirus capsid subunit enhances microtubular acetylation, and N-terminal residues 42 to 100 directly interact with the dynein IC1 subunit during retrograde transport. These findings highlight a mechanism whereby circoviruses recruit dynein for transport to the nucleus via the dynein/microtubule machinery.
在早期感染中，圆环病毒从细胞周边向细胞核的微管运输对于病毒复制至关重要。微管如何被招募到病毒货物上仍不清楚。在本研究中，我们观察到圆环病毒的运输依赖于微管聚合，并且进入的圆环病毒颗粒与细胞质动力蛋白和内体共定位。然而，圆环病毒与动力蛋白的结合独立于微管α-微管蛋白的存在以及细胞质动力蛋白向细胞核的转运。圆环病毒衣壳（Cap）亚基增强了微管乙酰化，并直接与动力蛋白的中间链1（IC1）相互作用。Cap病毒蛋白的N端42至100个残基是与动力蛋白IC1亚基有效结合和逆行运输所必需的。敲低IC1会降低病毒运输和复制。这些结果表明，Cap是细胞质动力蛋白IC1亚基的直接配体和微管α-微管蛋白乙酰化的诱导剂。此外，Cap招募宿主动力蛋白/微管机制，通过一种不同于生理动力蛋白货物的内体机制促进向细胞核的运输。
进入的病毒颗粒劫持宿主的细胞内运输机制，以便从细胞表面迁移到复制位点。更好地了解病毒与病毒蛋白之间的相互作用以及细胞内运输机制可能为抗病毒治疗提供新的靶点。目前，关于圆环病毒运输的分子机制知之甚少。在这里，我们报告圆环病毒颗粒进入早期内体，并利用与微管相关的分子马达动力蛋白沿着微管移动。圆环病毒衣壳亚基增强微管乙酰化，并且在逆行运输过程中，N端42至100个残基直接与动力蛋白IC1亚基相互作用。这些发现突出了一种机制，即圆环病毒通过动力蛋白/微管机制招募动力蛋白运输到细胞核。
