Molecular Determinants for Subcellular Localization of Hepatitis C Virus Core Protein
Molecular Determinants for Subcellular Localization of Hepatitis C Virus Core Protein
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DOI：
10.1128/jvi.79.2.1271-1281.2005
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发表时间：
2005-01
影响因子：
5.4
通讯作者：
R. Suzuki;S. Sakamoto;T. Tsutsumi;Akiko Rikimaru;Keiko Tanaka;T. Shimoike;K. Moriishi;T. Iwasaki-
中科院分区：
文献类型：
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作者：
R. Suzuki;S. Sakamoto;T. Tsutsumi;Akiko Rikimaru;Keiko Tanaka;T. Shimoike;K. Moriishi;T. Iwasaki-
丙型肝炎病毒（HCV）核心蛋白是一种具有多种调节功能的核衣壳蛋白。在组织培养细胞中，HCV核心蛋白主要定位于内质网以及细胞质内的线粒体和脂滴。然而，它也在一些细胞的细胞核中被检测到。为了阐明蛋白质的细胞运输控制的机制，我们进行了亚细胞分级分离实验，并使用共聚焦显微镜检查异源表达的融合蛋白的分布，涉及各种缺失和点突变的HCV核心结合绿色荧光蛋白。我们证明，跨越氨基酸112至152的区域可以介导的核心蛋白不仅与ER，而且与线粒体外膜的协会。该区域包含一个18个氨基酸的基序，预计可形成两亲性α-螺旋结构。关于核心蛋白的核靶向，我们确定了一种新的二分核定位信号，它需要三个碱性残基簇中的两个来进行有效的核转位，这可能是通过占据importin-α上的结合位点实现的。通过如上所述的多种靶向功能实现和维持的HCV核心蛋白的细胞运输的差异可以部分地调节核心蛋白的多种生物学作用。
ABSTRACT Hepatitis C virus (HCV) core protein is a putative nucleocapsid protein with a number of regulatory functions. In tissue culture cells, HCV core protein is mainly located at the endoplasmic reticulum as well as mitochondria and lipid droplets within the cytoplasm. However, it is also detected in the nucleus in some cells. To elucidate the mechanisms by which cellular trafficking of the protein is controlled, we performed subcellular fractionation experiments and used confocal microscopy to examine the distribution of heterologously expressed fusion proteins involving various deletions and point mutations of the HCV core combined with green fluorescent proteins. We demonstrated that a region spanning amino acids 112 to 152 can mediate association of the core protein not only with the ER but also with the mitochondrial outer membrane. This region contains an 18-amino-acid motif which is predicted to form an amphipathic α-helix structure. With regard to the nuclear targeting of the core protein, we identified a novel bipartite nuclear localization signal, which requires two out of three basic-residue clusters for efficient nuclear translocation, possibly by occupying binding sites on importin-α. Differences in the cellular trafficking of HCV core protein, achieved and maintained by multiple targeting functions as mentioned above, may in part regulate the diverse range of biological roles of the core protein.