Desrosiers R C, Lengyel P
Biochim Biophys Acta. 1979 May 24;562(3):471-80. doi: 10.1016/0005-2787(79)90110-2.
Reovirus mRNAs synthesized in vitro by the virionassociated enzyme have a 5' 'cap 1' structure (m7G(5')ppp(5')GmpCp...). However, about one third to one half of the reovirus mRNAs formed in mouse L929 cells have a 5' 'cap 2' structure (m7G(5')ppp(5')GmpCmp...) and the rest have a 5' 'cap 1' structure. The finding that virus mRNA 'cap' methylation is impaired in extracts of interferon-treated cells prompted us to study the effect of interferon on virus mRNA 'cap' methylation in vivo. Using labeling with [3H]-guanosine and dual labeling with [3H]methionine and [14C]uridine we compared the 5' structures of reovirus mRNAs accumulating between 5 and 11 h after infection in: L929 cells treated with 390 to 2600 U/ml of a partially purified mouse interferon preparation and untreated L929 cells. The treatment resulted in a 70 to 98% decrease in the 24 h virus yield and in a 50 to 55% decrease in the label accumulated in virus mRNAs. The 'capping' of virus mRNAs and the methylation of their 5' terminal and adjacent G residues were not diminished in interferon-treated cells. However, the percent of 'cap 2' termini was 36 to 47% lower in virus mRNAs from interferon-treated cells than in virus mRNAs from control cells. The interferon treatment did not result in the appearance of additional methylated nucleotides in the virus mRNAs.
由病毒体相关酶在体外合成的呼肠孤病毒mRNA具有5'“帽1”结构（m7G(5')ppp(5')GmpCp...）。然而，在小鼠L929细胞中形成的呼肠孤病毒mRNA约有三分之一到二分之一具有5'“帽2”结构（m7G(5')ppp(5')GmpCmp...），其余的具有5'“帽1”结构。干扰素处理细胞提取物中病毒mRNA“帽”甲基化受损这一发现促使我们研究干扰素在体内对病毒mRNA“帽”甲基化的影响。我们使用[3H] - 鸟苷标记以及[3H]甲硫氨酸和[14C]尿苷双重标记，比较了在感染后5至11小时内积累的呼肠孤病毒mRNA的5'结构：用390至2600 U/ml部分纯化的小鼠干扰素制剂处理的L929细胞和未处理的L929细胞。该处理导致24小时病毒产量降低70%至98%，病毒mRNA中积累的标记降低50%至55%。病毒mRNA的“加帽”及其5'末端和相邻G残基的甲基化在干扰素处理的细胞中并未减少。然而，干扰素处理细胞的病毒mRNA中“帽2”末端的百分比比对照细胞的病毒mRNA低36%至47%。干扰素处理并未导致病毒mRNA中出现额外的甲基化核苷酸。
