Liu Q, Tackney C, Bhat R A, Prince A M, Zhang P
Laboratory of Virology and Parasitology, The Lindsley F. Kimball Research Institute of the New York Blood Center, New York, New York 10021, USA.
J Virol. 1997 Jan;71(1):657-62. doi: 10.1128/JVI.71.1.657-662.1997.
Posttranslational processing and subcellular localization of the HCV core protein are critical steps involved in the assembly of hepatitis C virus (HCV). In this study, both of these events were investigated by in vitro translation and transient COS-1 cell transfection of core protein expression constructs. Mutations at amino acid residues 173 to 174 and 191 to 192 disrupted processing events at the two putative cleavage sites in the C-terminal hydrophobic region of the core protein, indicating that these residues are implicated in the pathway of core protein maturation. As a result, two forms of core protein, C173 and C191, were detected by immunoblotting. Indirect immunofluorescence experiments showed that core proteins C173 and C191, when produced from HCV full-length protein or various polyprotein precursors, displayed a cytoplasmic localization. The C173 species, however, was translocated to the nucleus when expressed in the absence of C191. These findings indicate that preferential cleavage may occur during core protein maturation and that the association of the C191 with the C173 species may contribute to the distinct subcellular distribution of core protein. This may provide a possible mechanism for the control of the diverse biological functions of core protein during HCV replication and assembly.
丙型肝炎病毒（HCV）核心蛋白的翻译后加工及亚细胞定位是HCV组装过程中的关键步骤。在本研究中，通过体外翻译以及核心蛋白表达构建体的瞬时COS - 1细胞转染对这两个事件进行了研究。核心蛋白C末端疏水区域两个假定切割位点处的氨基酸残基173至174以及191至192发生的突变破坏了加工事件，这表明这些残基与核心蛋白成熟途径有关。结果，通过免疫印迹检测到了两种形式的核心蛋白，即C173和C191。间接免疫荧光实验表明，当由HCV全长蛋白或各种多蛋白前体产生时，核心蛋白C173和C191定位于细胞质。然而，在没有C191表达时，C173会转移至细胞核。这些发现表明，核心蛋白成熟过程中可能发生优先切割，并且C191与C173的结合可能导致核心蛋白不同的亚细胞分布。这可能为HCV复制和组装过程中核心蛋白多种生物学功能的调控提供一种可能的机制。
