Peluso R W
Department of Microbiology, University of Minnesota, Minneapolis 55455.
J Virol. 1988 Aug;62(8):2799-807. doi: 10.1128/JVI.62.8.2799-2807.1988.
Multiple forms of the vesicular stomatitis virus nucleocapsid protein N have been detected in infected cells. One form is complexed with the viral NS protein in a 1:1 molar ratio, and the other forms are distinguished by their more rapid sedimentation rates on glycerol gradients. I performed a series of experiments designed to analyze the relationships between these forms of the N protein. Pulse-chase experiments demonstrate that the N protein is made first as the form which binds to the NS protein, forming a 1-to-1 molar complex, and that with increasing times of chase it is either assembled into nucleocapsids or converted to the two higher sedimenting forms. Using a newly developed quantitative immunoblotting procedure, I have quantitated the three differentially sedimenting species of the N protein and have shown that at later times postinfection (6 to 7 h), the faster-sedimenting forms of the N protein account for as much as 50% of the soluble N protein in the cell. The activity of these forms has been assessed, with only the 1-to-1 molar N-NS complex demonstrating the ability to support the replication and encapsidation of viral genomic RNA. A model for the conversion of the N protein from the active N-NS complex into the other forms of the protein is presented, and the possible function of the N-protein self-complexes is discussed.
在受感染的细胞中已检测到水泡性口炎病毒核衣壳蛋白N的多种形式。一种形式与病毒NS蛋白以1:1的摩尔比复合，其他形式则以它们在甘油梯度上更快的沉降速率为特征。我进行了一系列实验，旨在分析这些N蛋白形式之间的关系。脉冲追踪实验表明，N蛋白最初以与NS蛋白结合的形式产生，形成1:1的摩尔复合物，并且随着追踪时间的增加，它要么组装成核衣壳，要么转化为两种沉降更快的形式。使用新开发的定量免疫印迹程序，我对N蛋白的三种不同沉降的种类进行了定量，并表明在感染后较晚的时间（6至7小时），沉降更快的N蛋白形式占细胞中可溶性N蛋白的50%之多。已经评估了这些形式的活性，只有1:1摩尔的N-NS复合物显示出支持病毒基因组RNA复制和包装的能力。本文提出了一个将N蛋白从活性N-NS复合物转化为其他蛋白形式的模型，并讨论了N蛋白自身复合物的可能功能。
