Hausner T P, Nierhaus K H
Max-Planck-Institut für Molekulare Genetik, Abteilung Wittman, Berlin-Dahlem.
Biochem Int. 1988 Oct;17(4):617-27.
The ribonuclease alpha-sarcin exclusively cleaves the phosphodiester bond after G2661 in the 23S rRNA within 50S subunits, thus inactivating the ribosomes. The resulting alpha-fragment is 243 nucleotides long and contains the 3'-end of the 23S rRNA. The specificity is changed dramatically if isolated 23S rRNA is used as substrate. We have shown previously that 23S rRNA is digested completely except for two fragments, one of which is identical to the alpha-fragment. Here we show that the other fragment comprises the 5'-end of 23S rRNA and contains 385 nucleotides. A similar fragment was obtained when isolated 23S rRNA was digested with RNase A (specific for pyrimidines in single strands). It appears that the 5'-domain (equivalent to 5.8S rRNA of eukaryotic ribosomes) as well as the 3'-domain (equivalent to 4.5S rRNA of chloroplast ribosomes) have a compact and defined tertiary structure in isolated 23S rRNA in contrast to the rRNA region in between. Thus, alpha-sarcin is a convenient tool for detecting compact domains in isolated RNA.
核糖核酸酶α-肌动蛋白专一性地切割50S亚基内23S rRNA中G2661之后的磷酸二酯键，从而使核糖体失活。产生的α片段长243个核苷酸，包含23S rRNA的3'末端。如果使用分离的23S rRNA作为底物，特异性会发生显著变化。我们之前已经表明，除了两个片段外，23S rRNA被完全消化，其中一个片段与α片段相同。在这里我们表明，另一个片段包含23S rRNA的5'末端，含有385个核苷酸。当用核糖核酸酶A（对单链中的嘧啶具有特异性）消化分离的23S rRNA时，也获得了类似的片段。与两者之间的rRNA区域相比，似乎5'结构域（相当于真核核糖体的5.8S rRNA）以及3'结构域（相当于叶绿体核糖体的4.5S rRNA）在分离的23S rRNA中具有紧密且明确的三级结构。因此，α-肌动蛋白是检测分离RNA中紧密结构域的便捷工具。
