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The features and functions of influenza B virus BM2 protein in the process of virus particle formation.

乙型流感病毒BM2蛋白在病毒颗粒形成过程中的特征和功能。

基本信息

批准号：
13670310
负责人：
ODAGIRI Takato
金额：
$ 2.3万
依托单位：
National Institute of Infectious Diseases
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13670310/
关键词：
influenza B virus BM2 protein cytoplasmic transport type III membrane protein trans golgi network ヌクレオカプシド複合体細胞内輸送

项目摘要

A bicistronic mRNA transcribed from the influenza B virus RNA segment 7 encodes two viral proteins, matrix protein M1 and uncharacterized small protein BM2. Our previous findings indicate that BM2 is synthesized as a phosphoprotein at the late phase of infection, transported from the perinuclear region to the plasma membrane, and finally incorporated into the virion. In the present study, we focused on the cytoplasmic transport and cellular membrane association of BM2. Immunofluorescence studies of virus-infected and BM2 expression plasmid-transfected cells indicated that BM2 accumulated at the Golgi apparatus immediately after synthesis and then was transported to the plasma membrane through the trans-Golgi network. Localization of a set of BM2 deletion mutants revealed that the N-terminal half of BM2 (residues 2-50) was crucial for its transport ; in particular, the deletion of residues 2-23, deduced to be a transmembrane domain, resulted in diffused distribution of protein throughout the entire cells. Sucrose gradient flotation of the membrane showed that BM2 alone can associate with cellular membranes. Biochemical analysis of the membranes expressing BM2 further indicated that BM2 was tightly associated with cellular membranes as an integral membrane protein. Oligomerization of BM2 was demonstrated by co-precipitation of differentially epitope-tagged BM2 proteins. Furthermore, proteolytic analysis of the purifed virion showed that most part of the BM2 molecule exists in the interior of the virion. Taken together, these results strongly suggest that BM2 is integrated into the plasma membrane at the N-terminal hydrophobic domain in similar fashion to small proteins M2 and NB of influenza A and B viruses, respectively.

从B型流感病毒RNA片段7转录的双顺反子mRNA编码两种病毒蛋白，基质蛋白M1和未鉴定的小蛋白BM2。我们以前的发现表明，BM2在感染后期以磷酸蛋白的形式合成，从核周区运输到质膜，最后并入病毒粒子。在本研究中，我们重点研究了BM2的细胞质转运和细胞膜结合。对病毒感染和表达BM2的细胞的免疫荧光研究表明，BM2在合成后立即聚集在高尔基体，然后通过反式高尔基体网络运输到质膜。对一组BM2缺失突变体的定位表明，BM2的N端一半(残基2-50)对其运输至关重要，特别是残基2-23的缺失导致蛋白质在整个细胞中扩散分布。蔗糖梯度浮选表明BM2单独与细胞膜结合。对表达BM2的细胞膜的生化分析进一步表明，BM2作为一种完整的膜蛋白与细胞膜紧密结合。通过差异表位标记的BM2蛋白的共沉淀，证实了BM2的寡聚化。此外，对纯化的病毒粒子进行的蛋白质分解分析表明，BM2分子的大部分存在于病毒粒子的内部。综上所述，这些结果有力地表明，BM2以类似于甲型流感病毒和乙型流感病毒的小蛋白M2和Nb的方式整合到质膜的N端疏水结构域中。