Gottschling D E, Palen T E, Cech T R
Nucleic Acids Res. 1983 Apr 11;11(7):2093-109. doi: 10.1093/nar/11.7.2093.
The chromatin structure of the palindromic macronuclear ribosomal RNA genes of Tetrahymena thermophila was probed with micrococcal nuclease. Independent of the state of transcriptional activity, the transcribed region had a shorter nucleosome repeat (184 +/- 3 base pairs) than the non-transcribed central spacer or bulk chromatin (both 200 base pairs). The transcribed region displayed an increased sensitivity to micrococcal nuclease in rapidly growing cells, which suggested an altered chromatin structure during transcription. At early stages of nuclease digestion, the central spacer appeared to be in a highly structured nucleosomal array. Based on the differences in nucleosome repeat distance and sensitivity to nuclease, we conclude that quite different chromatin structures are maintained in two adjacent regions of the Tetrahymena ribosomal RNA gene. The DNA of the non-transcribed terminal spacer was found to contain sequences which are highly susceptible to micrococcal nuclease, precluding any conclusions about nucleosome structure in this region.
用微球菌核酸酶探测嗜热栖热四膜虫回文大核核糖体RNA基因的染色质结构。与转录活性状态无关，转录区域的核小体重复序列（184±3碱基对）比非转录的中央间隔区或整体染色质（均为200碱基对）短。在快速生长的细胞中，转录区域对微球菌核酸酶的敏感性增加，这表明转录过程中染色质结构发生了改变。在核酸酶消化的早期阶段，中央间隔区似乎处于高度结构化的核小体阵列中。基于核小体重复距离和对核酸酶敏感性的差异，我们得出结论，在四膜虫核糖体RNA基因的两个相邻区域维持着截然不同的染色质结构。发现非转录末端间隔区的DNA含有对微球菌核酸酶高度敏感的序列，因此无法得出该区域核小体结构的任何结论。
