Endo Y, Tsurugi K, Yutsudo T, Takeda Y, Ogasawara T, Igarashi K
Department of Biochemistry, Yamanashi Medical College, Japan.
Eur J Biochem. 1988 Jan 15;171(1-2):45-50. doi: 10.1111/j.1432-1033.1988.tb13756.x.
The site of action of a Vero toxin (VT2 or Shiga-like toxin II) from enterohemorrhagic Escherichia coli and Shiga toxin from Shigella dysenteriae 1 on eukaryotic ribosomes was studied. Treatment of eukaryotic ribosomes with either toxin caused the release of a fragment of 400 nucleotides from 28S ribosomal RNA when the isolated ribosomal RNA was treated with aniline. Release of this fragment with aniline treatment was accompanied by inhibition of protein synthesis and of elongation-factor-1-dependent aminoacyl-tRNA binding to ribosomes. Analysis of the nucleotide sequence of the 3'-terminal fragment of 553 nucleotides of 28S rRNA of rat liver 60S ribosomal subunits suggested that an adenine base at position 4324 (A-4324) was absent in toxin-treated 28S rRNA. Further analysis by thin-layer chromatography demonstrated quantitative release of adenine from rat liver ribosomes on treatment with the toxins. These results indicate that both VT2 and Shiga toxin inactivate 60S ribosomal subunits by cleaving the N-glycosidic bond at A-4324 in 28S ribosomal RNA.
对来自肠出血性大肠杆菌的维罗毒素（VT2或志贺样毒素II）以及痢疾志贺氏菌1型的志贺毒素在真核核糖体上的作用位点进行了研究。当用苯胺处理分离出的核糖体RNA时，用这两种毒素中的任何一种处理真核核糖体会导致28S核糖体RNA释放出一段400个核苷酸的片段。苯胺处理导致该片段的释放伴随着蛋白质合成以及延伸因子1依赖性氨酰tRNA与核糖体结合的抑制。对大鼠肝脏60S核糖体亚基28S rRNA的553个核苷酸的3'末端片段的核苷酸序列分析表明，在毒素处理的28S rRNA中，4324位的腺嘌呤碱基（A-4324）缺失。通过薄层色谱法的进一步分析表明，用毒素处理大鼠肝脏核糖体时，腺嘌呤会定量释放。这些结果表明，VT2和志贺毒素均通过切割28S核糖体RNA中A-4324处的N-糖苷键使60S核糖体亚基失活。
