Lee S Y, Bailey S C, Apirion D
J Bacteriol. 1978 Feb;133(2):1015-23. doi: 10.1128/jb.133.2.1015-1023.1978.
Small stable RNA molecules of Escherichia coli other than 5S (rRNA) and 4S (tRNA) were studied. Two of the molecules corresponded to 4.5S and 6S RNA, which have been reported previously. The third stable RNA molecule, 10S RNA, has not been described before. RNA labeled with (32)P(i) or [(14)C]uracil for a relatively long time, when separated in 5%/12% tandem polyacrylamide gels, displayed three bands corresponding to 10S, 6S, and 4.5S RNA in addition to rRNA and tRNA bands. These RNAs were stable in pulse-chase-labeling experiments. The amount of these RNAs was small, comprising only 0.2 to 0.5% of the total (32)P incorporation. However, this amount represented a large number of molecules; for 6S and 4.5S, it was about 1,000/DNA molecule. These three RNAs were found in the postribosomal supernatant fraction. None of them was found in purified nucleoid fractions in which the tightly coiled DNA molecules were contained. Of these three RNAs, 6S RNA was unique in that it seemed to exist in a ribonucleoprotein particle. All these RNAs, as well as tRNA, were very stable in the cell under various physiological conditions. 5S RNA was less stable. On the other hand, purified 6S RNA was more susceptible than tRNA to cell nucleases when incubated with cell extracts, suggesting that, being in a particle, it is protected from cell nucleases.
对大肠杆菌中除5S（核糖体RNA）和4S（转运RNA）以外的小稳定RNA分子进行了研究。其中两个分子分别对应于先前已报道的4.5S和6S RNA。第三个稳定RNA分子，即10S RNA，此前尚未被描述。用（32）P（i）或[（14）C]尿嘧啶标记较长时间的RNA，在5%/12%串联聚丙烯酰胺凝胶中分离时，除了核糖体RNA和转运RNA条带外，还显示出对应于10S、6S和4.5S RNA的三条条带。这些RNA在脉冲追踪标记实验中是稳定的。这些RNA的量很少，仅占总（32）P掺入量的0.2%至0.5%。然而，这个量代表了大量的分子；对于6S和4.5S，大约是1000个/DNA分子。这三种RNA存在于核糖体后上清液组分中。在含有紧密盘绕的DNA分子的纯化类核组分中未发现它们中的任何一种。在这三种RNA中，6S RNA是独特的，因为它似乎存在于核糖核蛋白颗粒中。所有这些RNA以及转运RNA在各种生理条件下在细胞中都非常稳定。5S RNA较不稳定。另一方面，纯化的6S RNA与细胞提取物一起孵育时比转运RNA更容易受到细胞核酸酶的作用，这表明，由于处于颗粒中，它受到细胞核酸酶的保护。
