Cao Shuai, Jiang Jingwen, Li Jing, Li Yan, Yang Limin, Wang Shanshan, Yan Jinghua, Gao George F, Liu Wenjun
Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
Center for Molecular Virology, CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China School of Life Sciences, University of Science and Technology of China, Hefei, China.
J Virol. 2014 Jul;88(13):7464-73. doi: 10.1128/JVI.00794-14. Epub 2014 Apr 16.
Influenza B virus is an enveloped negative-strand RNA virus that contributes considerably to annual influenza illnesses in human. The matrix protein of influenza B virus (BM1) acts as a cytoplasmic-nuclear shuttling protein during the early and late stages of infection. The mechanism of this intracellular transport of BM1 was revealed through the identification of two leucine-rich CRM1-dependent nuclear export signals (NESs) (3 to 14 amino acids [aa] and 124 to 133 aa), one bipartite nuclear localization signal (NLS) (76 to 94 aa), and two phosphorylation sites (80T and 84S) in BM1. The biological function of the NLS and NES regions were determined through the observation of the intracellular distribution of enhanced green fluorescent protein (EGFP)-tagged signal peptides, and wild-type, NES-mutant, and NLS-mutant EGFP-BM1. Furthermore, the NLS phosphorylation sites 80T and 84S, were found to be required for the nuclear accumulation of EGFP-NLS and for the efficient binding of EGFP-BM1 to human importin-α1. Moreover, all of these regions/sites were required for the generation of viable influenza B virus in a 12-plasmid virus rescue system.
This study expands our understanding of the life cycle of influenza B virus by defining the dynamic mechanism of the nucleocytoplasmic shuttle of BM1 and could provide a scientific basis for the development of antiviral medication.
乙型流感病毒是一种包膜负链RNA病毒，在人类每年的流感疾病中起重要作用。乙型流感病毒的基质蛋白（BM1）在感染的早期和晚期作为一种穿梭于细胞质和细胞核之间的蛋白。通过鉴定BM1中两个富含亮氨酸的依赖CRM1的核输出信号（NESs）（3至14个氨基酸[aa]和124至133 aa）、一个双分型核定位信号（NLS）（76至94 aa）以及两个磷酸化位点（80T和84S），揭示了BM1这种细胞内运输的机制。通过观察增强型绿色荧光蛋白（EGFP）标记的信号肽、野生型、NES突变型和NLS突变型EGFP - BM1的细胞内分布，确定了NLS和NES区域的生物学功能。此外，发现NLS磷酸化位点80T和84S是EGFP - NLS核积累以及EGFP - BM1与人输入蛋白α1有效结合所必需的。而且，在一个12质粒病毒拯救系统中，所有这些区域/位点对于产生有活力的乙型流感病毒都是必需的。
本研究通过定义BM1核质穿梭的动态机制，扩展了我们对乙型流感病毒生命周期的理解，并可为抗病毒药物的开发提供科学依据。
