Ohno H, Kaneko S, Lin Y, Kobayashi K, Murakami S
First Department of Internal Medicine, Faculty of Medicine, Kanazawa University, Ishikawa, Japan.
J Med Virol. 1999 May;58(1):11-8. doi: 10.1002/(sici)1096-9071(199905)58:1<11::aid-jmv2>3.0.co;2-h.
The X gene product of human hepatitis B virus, HBx, transactivates the expression of viral and cellular genes through a wide variety of cis elements, including the nuclear factor for IL-6 (NF-IL6) binding sites, although HBx does not appear to bind DNA directly. We previously reported that HBx transactivated the interleukin 8 promoter through NF-kappaB binding site and C/EBP-like binding site (NF-IL6 binding site). In this study, the interactions were examined between NF-IL6 and HBx using recombinant proteins. In a DNA-protein binding assay, the formation of a specific complex between NF-IL6 and a DNA probe harboring an NF-IL6 binding site was increased by the addition of either the full or the C-terminal 104 amino acids of HBx. A direct protein-protein binding assay (far-Western blot) revealed the direct interaction between the C-terminal 104 amino acids of HBx and the basic region-leucine zipper domain of NF-IL6. These results indicate that HBx alters the DNA-binding affinity of NF-IL6 through the direct interaction between the C-terminal domain of HBx and the basic region-leucine zipper domain of NF-IL6.
人类乙型肝炎病毒的X基因产物HBx，可通过多种顺式元件激活病毒和细胞基因的表达，这些元件包括白细胞介素6的核因子（NF-IL6）结合位点，尽管HBx似乎并不直接结合DNA。我们先前报道过，HBx通过NF-κB结合位点和C/EBP样结合位点（NF-IL6结合位点）激活白细胞介素8启动子。在本研究中，使用重组蛋白检测了NF-IL6与HBx之间的相互作用。在DNA-蛋白质结合试验中，通过添加HBx的全长或C端104个氨基酸，NF-IL6与携带NF-IL6结合位点的DNA探针之间特异性复合物的形成增加。直接蛋白质-蛋白质结合试验（远缘蛋白质印迹法）揭示了HBx的C端104个氨基酸与NF-IL6的碱性区域-亮氨酸拉链结构域之间的直接相互作用。这些结果表明，HBx通过HBx的C端结构域与NF-IL6的碱性区域-亮氨酸拉链结构域之间的直接相互作用，改变了NF-IL6的DNA结合亲和力。
