Keene M A, Elgin S C
Cell. 1981 Nov;27(1 Pt 2):57-64. doi: 10.1016/0092-8674(81)90360-3.
We have investigated micrococcal nuclease digestion of chromatin and purified DNA at the heat-shock locus 67B in Drosophila melanogaster. At early stages of the reaction a distinct set of fragments is generated, indicating the presence of preferential cleavage sites. These sites are also observed when purified recombinant plasmid DNA is used as the substrate, demonstrating that the sites are specified by the DNA sequence. At Drosophila locus 67B, prominent sites occur frequently, spaced approximately 200 bp apart, within the nontranscribed portions of the locus, but are generally not observed within the regions that are transcribed. In contrast, such sites are randomly distributed along the procaryotic plasmid pBR322. The results indicate that specific patterns of digestion of eucaryotic chromatin by micrococcal nuclease cannot be simply interpreted as the consequence of the nucleosome array. However, it is possible that the organization of eucaryotic DNA sequences detected by micrococcal nuclease bears a functional relationship to the organization of DNA by nucleosomes and, in fact, was so selected through evolution.
我们研究了黑腹果蝇热休克基因座67B处染色质和纯化DNA的微球菌核酸酶消化情况。在反应早期会产生一组独特的片段，这表明存在优先切割位点。当使用纯化的重组质粒DNA作为底物时也能观察到这些位点，这表明这些位点是由DNA序列指定的。在果蝇基因座67B处，显著位点在该基因座的非转录部分频繁出现，间隔约200 bp，但在转录区域通常未观察到。相比之下，这些位点沿原核质粒pBR322随机分布。结果表明，微球菌核酸酶对真核染色质的特定消化模式不能简单地解释为核小体阵列的结果。然而，微球菌核酸酶检测到的真核DNA序列的组织方式可能与核小体对DNA的组织方式存在功能关系，事实上，它是通过进化选择而来的。
