Curran J, Homann H, Buchholz C, Rochat S, Neubert W, Kolakofsky D
Department of Genetics and Microbiology, University of Geneva School of Medicine, Switzerland.
J Virol. 1993 Jul;67(7):4358-64. doi: 10.1128/JVI.67.7.4358-4364.1993.
The paramyxovirus nucleocapsid proteins (NPs) are relatively well conserved, except for the C-terminal 20% (or ca. 100 amino acids), referred to as the tail. We have examined whether this hypervariable tail is required for genome synthesis, both in vitro, where synthesis is predominantly from the input templates, and in vivo, where multiple rounds of amplification occur. In these viruses, genome synthesis and assembly of the nascent chain are coupled. We find that the tail is required in vivo but not in vitro. Closer examination of the in vivo system showed that the tailless NP could encapsidate the genome chain but that amplification did not occur. We interpret these results as indicating that the tail is not required for RNA assembly but is required for the template to function in RNA synthesis. Relatively small deletions within the conserved N-terminal 80% of the protein, on the other hand, rendered the protein nonfunctional in either system. The possible functions of the tail in RNA synthesis are discussed.
副粘病毒核衣壳蛋白（NP）相对保守，除了C末端20%（约100个氨基酸），即所谓的尾部。我们研究了这个高变尾部对于基因组合成是否必要，包括在体外（合成主要来自输入模板）和体内（发生多轮扩增）。在这些病毒中，基因组合成与新生链的组装是偶联的。我们发现尾部在体内是必需的，但在体外不是。对体内系统的进一步研究表明，无尾NP可以包裹基因组链，但扩增不会发生。我们将这些结果解释为表明尾部对于RNA组装不是必需的，但对于模板在RNA合成中发挥功能是必需的。另一方面，在该蛋白保守的N末端80%内相对小的缺失，使该蛋白在任一系统中都无功能。文中讨论了尾部在RNA合成中的可能功能。
