Reisbig R, Olsnes S, Eiklid K
J Biol Chem. 1981 Aug 25;256(16):8739-44.
The cytotoxic test system for Shigella shigae toxin was improved and used to study the stability of the toxin to various pH values, temperature, and chemicals. Inhibition of protein synthesis is the first demonstrable effect in cells treated with Shigella toxin. This inhibition appears to be at the level of peptide chain elongation. An inhibition effect on cell-free protein synthesis is exhibited by toxin pretreated first with trypsin and then with dithiothreitol and 8 M urea or 1% sodium dodecyl sulfate. Ribosomes treated with toxin or its A1 fragment had lost most of their ability to polymerize [14C]phenylalanine in a poly(U)-dependent cell-free system. Salt-washed ribosomes in simple buffered solutions were inactivated at a rate of at least 40 ribosomes/(min) (A1 fragment). Addition of antitoxin immediately stopped further inactivation, but it did not reactivate the inactivated ribosomes. 60 S ribosomal subunits from toxin-treated ribosomes had a marked reduction in ability to support polyphenylanine synthesis, whereas 40 S subunits from toxin-treated ribosomes retained their activity. Toxin-treated ribosomes retained their ability to incorporate [3H]puromycin into growing peptide chains, indicating that the peptide bond formation is not the function inhibited.
改进了痢疾志贺氏菌毒素的细胞毒性测试系统，并用于研究该毒素对不同pH值、温度和化学物质的稳定性。在用志贺氏菌毒素处理的细胞中，蛋白质合成的抑制是首先可证明的效应。这种抑制似乎发生在肽链延伸水平。先用胰蛋白酶处理，然后用二硫苏糖醇和8M尿素或1%十二烷基硫酸钠处理的毒素，对无细胞蛋白质合成表现出抑制作用。在依赖聚（U）的无细胞系统中，用毒素或其A1片段处理的核糖体失去了大部分聚合[14C]苯丙氨酸的能力。在简单缓冲溶液中用盐洗涤的核糖体以至少40个核糖体/（分钟）（A1片段）的速率失活。加入抗毒素立即停止进一步失活，但它不会使已失活的核糖体重新激活。来自毒素处理核糖体的60S核糖体亚基支持多聚苯丙氨酸合成的能力显著降低，而来自毒素处理核糖体的40S亚基保留了它们的活性。毒素处理的核糖体保留了将[3H]嘌呤霉素掺入生长肽链的能力，表明肽键形成不是被抑制的功能。
