Majeau Nathalie, Fromentin Rémi, Savard Christian, Duval Marie, Tremblay Michel J, Leclerc Denis
Infectious Disease Research Centre, CHUL, Université Laval, 2705 boulevard Laurier, Québec G1V 4G2, Canada.
J Biol Chem. 2009 Dec 4;284(49):33915-25. doi: 10.1074/jbc.M109.018549. Epub 2009 Sep 16.
Hepatitis C virus core protein is the viral nucleocapsid of hepatitis C virus. Interaction of core with cellular membranes like endoplasmic reticulum (ER) and lipid droplets (LD) appears to be involved in viral assembly. However, how these interactions with different cellular membranes are regulated is not well understood. In this study, we investigated how palmitoylation, a post-translational protein modification, can modulate the targeting of core to cellular membranes. We show that core is palmitoylated at cysteine 172, which is adjacent to the transmembrane domain at the C-terminal end of core. Site-specific mutagenesis of residue Cys(172) showed that palmitoylation is not involved in the maturation process carried out by the signal peptide peptidase or in the targeting of core to LD. However, palmitoylation was shown to be important for core association with smooth ER membranes and ER closely surrounding LDs. Finally, we demonstrate that mutation of residue Cys(172) in the J6/JFH1 virus genome clearly impairs virion production.
丙型肝炎病毒核心蛋白是丙型肝炎病毒的病毒核衣壳。核心蛋白与内质网（ER）和脂滴（LD）等细胞膜的相互作用似乎参与了病毒组装。然而，这些与不同细胞膜的相互作用是如何被调节的，目前还不太清楚。在本研究中，我们研究了蛋白质翻译后修饰——棕榈酰化如何调节核心蛋白靶向细胞膜。我们发现核心蛋白在第172位半胱氨酸处发生棕榈酰化，该位点与核心蛋白C末端的跨膜结构域相邻。对第172位半胱氨酸残基进行位点特异性诱变表明，棕榈酰化不参与信号肽肽酶介导的成熟过程，也不参与核心蛋白靶向脂滴。然而，棕榈酰化对于核心蛋白与光滑内质网膜以及紧密围绕脂滴的内质网的结合很重要。最后，我们证明J6/JFH1病毒基因组中第172位半胱氨酸残基的突变明显损害病毒粒子的产生。
