LOCATION OF HISTONES ON SIMIAN VIRUS 40 DNA
LOCATION OF HISTONES ON SIMIAN VIRUS 40 DNA
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DOI：
10.1073/pnas.72.8.2895
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发表时间：
1975-01-01
影响因子：
11.1
通讯作者：
MCCARTHY, B
中科院分区：
文献类型：
--
作者：
POLISKY, B;MCCARTHY, B
用位点特异性限制性内切酶检测了从纯化病毒粒子分离的猿猴病毒40 dna -组蛋白复合物中组蛋白分子的物理位置。该复合物含有四种宿主组蛋白，但缺乏组蛋白F1。组蛋白通过两种限制性内切酶HindIII和EcoRI阻止SV40 DNA的完全切割。从HindIII内切酶切割组蛋白-DNA复合体产生的DNA片段模式来看，纯化的SV40 DNA上有6个断裂，我们得出结论，组蛋白在SV40 DNA上相对于限制性内切酶切割位点是随机排列的。EcoRI内切酶在SV40 NDA中产生一个断裂，用于确定组蛋白对SV40 DNA分子的物理覆盖程度。我们观察到复合物中80%的EcoRI位点可以被酶进入，而20%是“封闭的”。这种覆盖程度与复合物中DNA：组蛋白的质量比是一致的，这是由甲醛固定复合物的浮力密度所揭示的。我们得出结论，该复合体中的组蛋白随机分布在SV 40基因组上，覆盖了大约20%的DNA。这些结果表明，组蛋白种类F2b、F2al、F2a2和F3与sv40 DNA的核苷酸序列无关。
The physical location of histone molecules in a simian virus 40 DNA-histone complex isolated from purified virions was examined using site-specific restriction endonucleases. The complex contains four host histone species but lacks histone F1. Histones prevent complete cleavage of SV40 DNA by two restriction enzymes, HindIII and EcoRI. From the pattern of DNA fragments resulting from cleavage of the histone-DNA complex by the HindIII endonuclease, which makes six breaks on purified SV 40 DNA, we have concluded that histones are randomly arranged on SV40 DNA relative to restriction enzyme cleavage sites. The EcoRI endonuclease, which makes one break in SV40 NDA, was used to determine the degree of physical coverage of the SV 40 DNA molecule by histones. We observed that 80% of the EcoRI sites in the complex are accessible to the enzyme while 20% are "closed." This degree of coverage is consistent with the mass ratio of DNA:histone in the complex as revealed by the buoyant density of the formaldehyde-fixed complex. We conclude that the histones in the complex are located randomly on the SV 40 genome and cover approximatley 20% of the DNA. These results suggest that the histone species F2b, F2al, F2a2, and F3 are bound without regard to nucleotide sequence of SV 40 DNA.