Guarino L A, Dong W, Xu B, Broussard D R, Davis R W, Jarvis D L
Department of Biochemistry and Biophysics, Texas A&M University, College Station.
J Virol. 1992 Dec;66(12):7113-20. doi: 10.1128/JVI.66.12.7113-7120.1992.
The PstI K fragment of Autographa californica nuclear polyhedrosis virus (AcMNPV) encodes a protein with a molecular weight of 31,000. To define the role of this protein (pp31) in virus infection further, it was overexpressed in bacteria and used to produce polyclonal antiserum. Radioimmunoprecipitation analysis indicated that pp31 was synthesized during both the early and late phases of virus infection, consistent with previous analyses indicating that the gene was regulated by tandem early and late promoters. Metabolic labeling of cells with carrier-free phosphate indicated that pp31 was phosphorylated. Biochemical fractionation experiments showed that pp31 was localized in the nucleus and that it was more stably associated with the nucleus at later times of infection. Immunoblot analysis of subnuclear fractions indicated that pp31 was associated predominantly with the chromatin and nuclear matrix fractions. Immunofluorescence experiments confirmed that the pp31 protein was localized in the nucleus. Nuclear staining was relatively uniform early but was more centrally nuclear later in infection. Immunoelectron microscopy indicated that the pp31 protein was a component of virogenic stroma. Southwestern (DNA-protein) blot analysis demonstrated that pp31 is a DNA-binding protein. These findings suggest a possible role for pp31 in the virus life cycle.
苜蓿银纹夜蛾核型多角体病毒（AcMNPV）的PstI K片段编码一种分子量为31,000的蛋白质。为了进一步确定该蛋白质（pp31）在病毒感染中的作用，在细菌中对其进行了过表达，并用于制备多克隆抗血清。放射免疫沉淀分析表明，pp31在病毒感染的早期和晚期均有合成，这与之前的分析一致，即该基因受串联的早期和晚期启动子调控。用无载体磷酸盐对细胞进行代谢标记表明pp31被磷酸化。生化分级分离实验表明，pp31定位于细胞核，并且在感染后期与细胞核的结合更稳定。对亚核组分的免疫印迹分析表明，pp31主要与染色质和核基质组分相关。免疫荧光实验证实pp31蛋白定位于细胞核。早期核染色相对均匀，但在感染后期更集中于细胞核中央。免疫电子显微镜表明，pp31蛋白是病毒发生基质的一个组成部分。西南（DNA-蛋白质）印迹分析表明pp31是一种DNA结合蛋白。这些发现提示了pp31在病毒生命周期中可能发挥的作用。
