Szkopińska A, Zagórski W, Zagórska L, Szafrański P
Eur J Biochem. 1975 Dec 1;60(1):289-94. doi: 10.1111/j.1432-1033.1975.tb21002.x.
f2 phage RNA treated with O-methylhydroxylamine under denaturing conditions loses its ordered structure with consequent exposure of the normally hidden initiation codons. In the presence of Escherichia coli ribosomes and crude initiation factors modified f2 RNA binds about 50 times more f-[3H]Met-tRNA than native f2 RNA. The interaction of native f2[14C]RNA with ribosomes requires initiation factors. The binding of O-methylhydroxylamine-modified f2 [14C]RNA to E. coli 70-S or 20-S ribosomes does not depend on the presence of initiation factors. A significant number of ribosomes deficient in initiation factors interact with a molecule of modified f2 [14C]RNA. Treatment of the resultant polysomal complex with pancreatic RNase yields ribosomes with f2 RNA fragments protected against RNase. Almost all AUG/GUG codons in the f2 RNA are located on the RNase-insensitive ribosome-bound fragments, constituting only 25% of the entire molecule. Addition of crude initiation factors to such ribosomes with fragments of modified f2 RNA promotes binding of f-[3H]Met-tRNA. The resultant complex is fully reactive with puromycin. No binding of Ac-Phe-tRNA takes place under similar conditions.
在变性条件下用O-甲基羟胺处理的f2噬菌体RNA会失去其有序结构，从而使通常隐藏的起始密码子暴露出来。在存在大肠杆菌核糖体和粗制起始因子的情况下，经修饰的f2 RNA结合f-[3H]甲硫氨酰-tRNA的能力比天然f2 RNA高约50倍。天然f2[14C]RNA与核糖体的相互作用需要起始因子。O-甲基羟胺修饰的f2 [14C]RNA与大肠杆菌70-S或20-S核糖体的结合不依赖于起始因子的存在。大量缺乏起始因子的核糖体与一个经修饰的f2 [14C]RNA分子相互作用。用胰核糖核酸酶处理所得的多核糖体复合物会产生带有受核糖核酸酶保护的f2 RNA片段的核糖体。f2 RNA中几乎所有的AUG/GUG密码子都位于对核糖核酸酶不敏感的核糖体结合片段上，这些片段仅占整个分子的25%。向带有经修饰的f2 RNA片段的核糖体中添加粗制起始因子会促进f-[3H]甲硫氨酰-tRNA的结合。所得复合物与嘌呤霉素完全反应。在类似条件下不会发生乙酰苯丙氨酰-tRNA的结合。
