Kaufmann Y, Zamir A
Eur J Biochem. 1975 May 6;53(2):599-603. doi: 10.1111/j.1432-1033.1975.tb04103.x.
Ribosomal binding complexes directed by poly(U) or T4 mRNA were formed with aminoacyl-tRNA or its derivatives bound to predominantly the P or A binding site. The defined binding complexes were reacted with colicin E3 and the reaction was assessed by the ability of the complexes to proceed with polypeptide synthesis. The results indicated that only one of the four complexes tested was completely resistant to colicin E3-induced inactivation: that of Phe-tRNA bound in the presence of poly(U) to the A-site. The poly(U) directed complex of AcPhe-tRNA and the T4-mRNA-directed complex at the A-site appeared slightly resistant, while the T4 mRNA initiation complex was inactivated by colicin E3 in a manner similar to non-complexed ribosomes. Colicin E3 added to ribosomes after protein synthesis had been initiated affected the subsequent polymerization in a manner corresponding to the response of the binding complexes. Thus, poly(U)-translating ribosomes were less affected than ribosomes translating the viral mRNA. The vulnerability of natural-mRNA-directed binding complexes to inactivation by colicin E3 is in accord with the mode of inactivation by the colicin in vivo.
由聚（U）或T4 mRNA引导的核糖体结合复合物是由氨基酰 - tRNA或其衍生物形成的，这些衍生物主要结合在P或A结合位点上。将确定的结合复合物与大肠杆菌素E3反应，并通过复合物进行多肽合成的能力来评估反应。结果表明，所测试的四种复合物中只有一种对大肠杆菌素E3诱导的失活完全抗性：即在聚（U）存在下结合到A位点的苯丙氨酰 - tRNA的复合物。乙酰苯丙氨酰 - tRNA的聚（U）引导复合物和A位点的T4 - mRNA引导复合物似乎略有抗性，而T4 mRNA起始复合物被大肠杆菌素E3以类似于未复合核糖体的方式失活。在蛋白质合成开始后添加到核糖体上的大肠杆菌素E3以与结合复合物的反应相对应的方式影响随后的聚合。因此，翻译聚（U）的核糖体比翻译病毒mRNA的核糖体受影响小。天然mRNA引导的结合复合物对大肠杆菌素E3失活的敏感性与该大肠杆菌素在体内的失活模式一致。
