Silverman B, Mirsky A E
Proc Natl Acad Sci U S A. 1973 Sep;70(9):2637-41. doi: 10.1073/pnas.70.9.2637.
The ability of histones to block the accessibility of DNA in chromatin to DNA and RNA polymerases was measured by addition of lysine-rich or arginine-rich histones to nuclei selectively depleted of these histones. By this procedure nuclei were obtained in which all of the original lysine-rich histone in the chromatin was replaced by arginine-rich histone. Conversely in other nuclei, additional lysine-rich histone replaced some of the endogenous arginine-rich histone. Lysine-rich histone was much more effective than arginine-rich histone in blocking accessibility to DNA polymerase. Both classes of histone inhibited template activity toward RNA polymerase to a similar extent. In addition to lysine-rich histone and total arginine-rich histone, phosphorylated lysine-rich histone, two fragments of lysine-rich histone produced by cleavage with N-bromosuccinamide, and fractions IIB and IV of arginine-rich histone were added to histone-depleted nuclei. With both DNA and RNA polymerases as probes, no differences in inhibition of template activity were found when native lysine-rich histone was compared to phosphorylated lysine-rich histone. Similarly, fractions IIB and IV were indistinguishable from total arginine-rich histone. On a molar basis, the carboxyl fragment of lysine-rich histone was as effective as intact lysine-rich histone only when the amino fragment was added to it. By itself, the amino portion of lysine-rich histone was without inhibitory effect in the RNA polymerase assay and resulted in only slight inhibition of template activity toward DNA polymerase.
通过向选择性去除这些组蛋白的细胞核中添加富含赖氨酸或富含精氨酸的组蛋白，来测定组蛋白阻断染色质中DNA对DNA和RNA聚合酶的可及性的能力。通过该程序获得的细胞核中，染色质中所有原始的富含赖氨酸的组蛋白都被富含精氨酸的组蛋白所取代。相反，在其他细胞核中，额外的富含赖氨酸的组蛋白取代了一些内源性富含精氨酸的组蛋白。在阻断对DNA聚合酶的可及性方面，富含赖氨酸的组蛋白比富含精氨酸的组蛋白有效得多。两类组蛋白对RNA聚合酶模板活性的抑制程度相似。除了富含赖氨酸的组蛋白和总富含精氨酸的组蛋白外，还将磷酸化的富含赖氨酸的组蛋白、用N-溴代琥珀酰胺裂解产生的富含赖氨酸的组蛋白的两个片段以及富含精氨酸的组蛋白的IIB和IV组分添加到去除组蛋白的细胞核中。以DNA和RNA聚合酶作为探针，当将天然的富含赖氨酸的组蛋白与磷酸化的富含赖氨酸的组蛋白进行比较时，未发现模板活性抑制方面的差异。同样，IIB和IV组分与总富含精氨酸的组蛋白没有区别。以摩尔为基础，仅当向富含赖氨酸的组蛋白的羧基片段添加氨基片段时，其才与完整的富含赖氨酸的组蛋白一样有效。就其本身而言，富含赖氨酸的组蛋白的氨基部分在RNA聚合酶测定中没有抑制作用，并且仅对DNA聚合酶的模板活性产生轻微抑制。
