Hausner T P, Atmadja J, Nierhaus K H
Max-Planck-Institut für Molekulare Genetik, Abt. Wittmann, Berlin, Dahlem, Germany.
Biochimie. 1987 Sep;69(9):911-23. doi: 10.1016/0300-9084(87)90225-2.
Alpha-sarcin cleaves one phosphodiester bond of 23S rRNA within 70S ribosomes or 50S subunits derived from E. coli. The resulting fragment was isolated and sequenced. The cleavage site was identified as being after G2661 and is located within a universally conserved dodecamer. Cleavage after G2661 specifically blocked the binding of both elongation factors, i.e. that of the ternary complex Phe-tRNAEF-TuGMPPNP and of EF-G*GMPPNP, whereas all elongation-factor independent functions of the ribosome, such as association of the ribosomal subunits, tRNA binding to A and P sites, the accuracy of tRNA selection at both sites, the peptidyl transferase activity, and the EF-G independent, spontaneous translocation, were not affected at all. Control experiments with wheat germ ribosomes yielded an equivalent inhibition pattern. The data suggest that the universally conserved dodecamer containing the cleavage site G2661 is located at the presumably overlapping region of the binding sites of both elongation factors.
α-肌动蛋白切割来自大肠杆菌的70S核糖体或50S亚基内23S rRNA的一个磷酸二酯键。分离并测序了产生的片段。切割位点被确定为在G2661之后，并且位于一个普遍保守的十二聚体内。G2661之后的切割特异性地阻断了两种延伸因子的结合，即三元复合物Phe-tRNAEF-TuGMPPNP和EF-G*GMPPNP的结合，而核糖体的所有不依赖延伸因子的功能，如核糖体亚基的结合、tRNA与A和P位点的结合、两个位点上tRNA选择的准确性、肽基转移酶活性以及不依赖EF-G的自发转位，均未受到任何影响。用小麦胚芽核糖体进行的对照实验产生了等效的抑制模式。数据表明，包含切割位点G2661的普遍保守的十二聚体位于两种延伸因子结合位点的大概重叠区域。
