Bock C T, Schranz P, Schröder C H, Zentgraf H
German Cancer Research Centre, Heidelberg, FRG.
Virus Genes. 1994 Jul;8(3):215-29. doi: 10.1007/BF01703079.
Hepatitis B virus (HBV) nucleoprotein complexes were isolated from nuclei of the human hepatoblastoma cell line HepG2.2.15. Under conditions of physiological ionic strength, the complexes sedimented at a rate corresponding to about 82 S. They contained viral DNA, histone, and nonhistone proteins. For DNA a circular, covalently closed structure was shown both by CsCl gradient centrifugation and electron microscopy. Spread preparations revealed the typical "beads-on-a-string" appearance of nucleosomally organized DNA. The average number of nucleosomes was 18, resulting in a biochemical repeat unit of HBV chromatin of approximately 180 base pairs of DNA. This value was confirmed by experiments analyzing the structure of the HBV chromatin by the use of micrococcal nuclease. Electron microscopy demonstrated that exposure to high ionic strength conditions resulted in removal of nucleosomes from the complexes, but also revealed proteinaceous structures remaining bound to viral DNA molecules. The nature of these residual proteins is discussed. Since native nucleoprotein complexes could be precipitated with HBV-core antibodies, core protein appeared to be one of the nonhistone proteins.
从人肝癌细胞系HepG2.2.15的细胞核中分离出乙型肝炎病毒（HBV）核蛋白复合物。在生理离子强度条件下，这些复合物以约82 S的速率沉降。它们含有病毒DNA、组蛋白和非组蛋白。通过氯化铯梯度离心和电子显微镜观察，DNA呈现出环状、共价闭合结构。铺展制备物显示出核小体组织化DNA典型的“串珠”外观。核小体的平均数量为18个，导致HBV染色质的生化重复单元约为180个DNA碱基对。通过使用微球菌核酸酶分析HBV染色质结构的实验证实了该值。电子显微镜显示，暴露于高离子强度条件下会导致复合物中的核小体被去除，但也揭示了仍与病毒DNA分子结合的蛋白质结构。讨论了这些残留蛋白质的性质。由于天然核蛋白复合物可以用HBV核心抗体沉淀，核心蛋白似乎是其中一种非组蛋白。
