Chan Chio Mui, Zhou Chun, Huang Raven H
Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
Science. 2009 Oct 9;326(5950):247. doi: 10.1126/science.1179480.
Ribotoxins kill cells by endonucleotically cleaving essential RNAs involved in protein translation. We report here that a stable heterotetramer composed of two bacterial proteins, Pnkp and Hen1, was able to repair transfer RNAs cleaved by ribotoxins in vitro. Before the broken RNAs were ligated by the heterotetramer, a methyl group was added to the 2'-OH group that participated in the original RNA cut. Because of the methylation, RNAs repaired by bacterial Pnkp/Hen1 heterotetramer could not be cleaved again by the ribotoxins. Thus, unlike eukaryotic Hen1 involved in RNA interference, the bacterial Hen1 is part of an RNA repair and modification system.
核糖体毒素通过对参与蛋白质翻译的必需RNA进行核酸内切切割来杀死细胞。我们在此报告，由两种细菌蛋白Pnkp和Hen1组成的稳定异源四聚体能够在体外修复被核糖体毒素切割的转运RNA。在断裂的RNA被异源四聚体连接之前，一个甲基被添加到参与原始RNA切割的2'-OH基团上。由于甲基化作用，由细菌Pnkp/Hen1异源四聚体修复的RNA不能再被核糖体毒素切割。因此，与参与RNA干扰的真核生物Hen1不同，细菌Hen1是RNA修复和修饰系统的一部分。
