Nitta I, Ueda T, Watanabe K
Department of Chemistry & Biotechnology, Graduate School of Engineering, University of Tokyo, Japan.
RNA. 1998 Mar;4(3):257-67.
Experimental results are presented suggesting that 23S rRNA is directly involved in the peptide bond formation usually performed on the ribosome. Although several reports have indicated that the eubacterial peptidyltransferase reaction does not necessarily require all the ribosomal proteins, the reconstitution of peptidyltransferase activity by a naked 23S rRNA without the help of any of the ribosomal proteins has not been reported previously. It is demonstrated that an E. coli 23S rRNA transcript synthesized by T7 RNA polymerase in vitro was able to promote peptide bond formation in the presence of 0.5% SDS. The reaction was inhibited by the peptidyltransferase-specific antibiotics chloramphenicol and carbomycin, and by digestion with RNases A and T1. Site-directed mutageneses at two highly conserved regions close to the peptidyltransferase center ring, G2252 to U2252 and C2507G2581 to U2507A2581, also suppressed peptide bond formation. These findings strongly suggest that 23S rRNA is the peptidyltransferase itself.
实验结果表明，23S rRNA直接参与通常在核糖体上进行的肽键形成。尽管有几份报告指出，真细菌肽基转移酶反应不一定需要所有核糖体蛋白，但此前尚未报道过在没有任何核糖体蛋白帮助的情况下，由裸露的23S rRNA重建肽基转移酶活性。结果表明，体外由T7 RNA聚合酶合成的大肠杆菌23S rRNA转录本在0.5% SDS存在下能够促进肽键形成。该反应受到肽基转移酶特异性抗生素氯霉素和碳霉素以及用核糖核酸酶A和T1消化的抑制。在靠近肽基转移酶中心环的两个高度保守区域G2252至U2252以及C2507G2581至U2507A2581进行的定点诱变也抑制了肽键形成。这些发现有力地表明，23S rRNA本身就是肽基转移酶。
