Walden W E, Godefroy-Colburn T, Thach R E
J Biol Chem. 1981 Nov 25;256(22):11739-46.
SC-1 cells infected with reovirus continue to synthesize host proteins at a nearly normal rate for at least 12 h postinfection. The relative translational efficiencies of reovirus and host mRNAs were determined at various times during this interval. Analysis was performed by determining the sensitivity of individual mRNA translation rates to inhibition by low doses of cycloheximide, by measuring polysome sizes, and by quantitatively comparing mRNA concentration with protein synthesis rates. Treatment of infected cells with low doses of cycloheximide actually stimulates the synthesis of some of the major reovirus protein, whereas host protein synthesis is inhibited. An analysis of the polysomes encoding two reovirus proteins (microNS and sigma 3; synthesis of both is stimulated by cycloheximide) shows that these proteins are synthesized on polysomes smaller than those producing host proteins of comparable size. Reovirus mRNAs accumulate to unusually high levels during the first 8 h of infection, accounting for 30% to 45% by weight of the total mRNA in the cell. We interpret these results as indicating that viral and host mRNAs must compete for a message-discriminatory component prior to their binding to the 40 S ribosomal complex and that this component is limiting in reovirus-infected cells. Moreover, a hierarchy must exist among mRNAs in terms of their affinity for this component, host mRNAs in general having greater affinities than reovirus mRNAs.
感染呼肠孤病毒的SC - 1细胞在感染后至少12小时内仍以接近正常的速率继续合成宿主蛋白。在此期间的不同时间测定了呼肠孤病毒和宿主mRNA的相对翻译效率。通过确定低剂量环己酰亚胺对单个mRNA翻译速率的抑制敏感性、测量多核糖体大小以及定量比较mRNA浓度与蛋白质合成速率来进行分析。用低剂量环己酰亚胺处理感染的细胞实际上会刺激一些主要呼肠孤病毒蛋白的合成，而宿主蛋白合成则受到抑制。对编码两种呼肠孤病毒蛋白（微小NS和σ3；两者的合成均受环己酰亚胺刺激）的多核糖体分析表明，这些蛋白是在比产生大小相当的宿主蛋白的多核糖体更小的多核糖体上合成的。呼肠孤病毒mRNA在感染的最初8小时内积累到异常高的水平，占细胞中总mRNA重量的30%至45%。我们将这些结果解释为表明病毒和宿主mRNA在与40S核糖体复合物结合之前必须竞争一种信息区分成分，并且这种成分在呼肠孤病毒感染的细胞中是有限的。此外，就mRNA对该成分的亲和力而言，必须存在一种等级制度，一般来说宿主mRNA的亲和力比呼肠孤病毒mRNA的亲和力更大。
