Length and sequence heterogeneity of the histone gene repeat unit of the sea urchin, S. purpuratus
Length and sequence heterogeneity of the histone gene repeat unit of the sea urchin, S. purpuratus
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海胆组蛋白基因重复单元的长度和序列异质性
DOI：
10.1016/0092-8674(78)90111-3
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发表时间：
1978
期刊：
影响因子：
64.5
通讯作者：
E. Weinberg
中科院分区：
文献类型：
--
作者：
G. Overton;E. Weinberg
紫斑链霉菌中的组蛋白基因重复序列具有可变的长度和序列。两个含有全长6.3kb组蛋白重复单位的重组质粒在重复结构的两个位置上长度不同，并且出现了两个限制性内切酶识别位点。在5个海胆的完整DNA和密度梯度法富含组蛋白基因序列的DNA样本中，也显示了重复长度的差异。每个个体中的重复序列属于非常有限的主要类别，这些类别在总长度或特定限制酶位点的分布和存在方面可能彼此不同。研究发现，重复序列的许多区域都会发生变异；有些变异被专门定位到间隔区。尽管发现的重复序列的绝对长度差异很小，但由于没有一种类型的重复序列对所有个体都是共同的，所以个体之间的重复序列可能有很大的不同。前言组蛋白基因簇(HDNA)是重复DNA编码结构蛋白的最广泛的例子。在海胆中，5个主要组蛋白类别的编码区包含在一个6-7kb的重复单元中(Birnstiel等人，1975；Kedes等人，1975a，1975b；Weinberg等人，1975；Cohn，Lowry和Kedes，1976；Portmann，Schaffner和Birnstiel，1976；Schaffner等人，1976；Wu等人，1976；Holmes等人，1977)，被随意重复数百次(Kedes和Birnstiel，1971；Weinberg等，1972；Grunstein，Schedl和Kedes，1973a；Grunstein和Schedl，1976)。未知功能的间隔区占重复单位的近60%，并分隔五个编码区(Kedes和Birnstiel，1971；Portmann等人，1976；Wu等人，1976；Holmes等人，1977)。HDNA与非洲爪哇的28+18S核糖体基因和5S核糖体基因在结构上有显著的相似性。然而，一个主要的区别是hDNA明显缺乏长度或序列异质性(Kedes，1976)。此时将显示重复单位的长度
Histone gene repeats in S. purpuratus are shown to be of variable length and sequence. Two recombinant plasmids containing the full-length 6.3 kb histone repeat unit are found to differ in length at two sites in the repeating structure and in the occurrence of two restriction enzyme recognition sites. Variation in repeat length is also demonstrated in the unfractionated DNA of five sea urchins and in a sample of DNA enriched for histone gene sequences by density gradient methods. The repeats in each individual are of a very limited number of major classes, which may differ from one another in overall length or in distribution and presence of particular restriction enzyme sites. Variations are found to occur at many regions of the repeat; some have been mapped specifically to spacer regions. Repeats may differ dramatically from individual to individual since there is no one type of repeat class common to all, although the absolute length differences of the repeats that are found are small. introductionThe histone gene cluster (hDNA) is the most extensively characterized example of repeated DNA coding for structural proteins. In the sea urchin, the coding regions for the five major histone classes are contained in a 6-7 kb repeat unit (Birnstiel et al., 1975; Kedes et al., 1975a, 1975b; Weinberg et al., 1975; Cohn, Lowry and Kedes, 1976; Portmann, Schaffner and Birnstiel, 1976; Schaffner et al., 1976; Wu et al., 1976; Holmes et al., 1977) which is tandemly reiterated several hundred fold (Kedes and Birnstiel, 1971;. Weinberg et al., 1972; Grunstein, Schedl and Kedes, 1973a; Grunstein and Schedl, 1976). Spacer regions of unknown function account for nearly 60% of the repeat unit and separate the five coding regions (Kedes and Birnstiel, 1971; Portmann et al., 1976; Wu et al., 1976; Holmes et al., 1977). There are striking parallels in structure between hDNA and other repeated genes such as the 28+ 18s ribosomal genes and the 5s ribosomal genes of Xenopus laevis. One major difference, however, is the apparent lack of length or sequence heterogeneity of the hDNA (Kedes, 1976). The length of the repeating unit appears