Axel R, Melchior W, Sollner-Webb B, Felsenfeld G
Proc Natl Acad Sci U S A. 1974 Oct;71(10):4101-5. doi: 10.1073/pnas.71.10.4101.
Staphylococcal nuclease digestion of purified chromatin from duck reticulocytes or calf thymus results in the production of a series of double-stranded DNA fragments of discrete molecular size, ranging from about 130 to 45 base pairs, which can be detected by polyacrylamide gel electrophoresis. Similar patterns of protected DNA fragments are obtained from limit digests of chromatin "reconstituted" from purified DNA and chromatin proteins. The results obtained with reconstituted material do not depend upon the origin of the DNA, which may be derived from a bacterial, viral, or homologous source. The specificity of the protective mechanism, therefore, resides in the structure of the bound histones, and probably not in any special nucleotide sequences present in the DNA. Removal of lysine-rich histones from chromatin before digestion results principally in disappearance from the digest of a DNA fragment about 130 base pairs long. Our preliminary results suggest that other elements of the digest pattern can be assigned uniquely to the remaining histone components. These results indicate that the binding of histones to DNA in chromatin involves a limited number of specific and very well defined contacts between protein and nucleic acid, which arise from structural properties of the histones.
用葡萄球菌核酸酶消化鸭网织红细胞或小牛胸腺的纯化染色质，会产生一系列分子大小离散的双链DNA片段，范围从约130到45个碱基对，可通过聚丙烯酰胺凝胶电泳检测到。从由纯化的DNA和染色质蛋白“重构”的染色质的极限消化中也可获得类似的受保护DNA片段模式。用重构材料获得的结果并不取决于DNA的来源，DNA可能来自细菌、病毒或同源来源。因此，保护机制的特异性存在于结合的组蛋白结构中，可能不在于DNA中存在的任何特殊核苷酸序列。消化前从染色质中去除富含赖氨酸的组蛋白，主要导致消化物中约130个碱基对长的DNA片段消失。我们的初步结果表明，消化模式的其他成分可以唯一地归因于其余的组蛋白成分。这些结果表明，染色质中组蛋白与DNA的结合涉及蛋白质与核酸之间有限数量的特定且定义明确的接触，这源于组蛋白的结构特性。
