Molecular origin of the mosaic sequence arrangements of higher primate alpha-globin duplication units.
Molecular origin of the mosaic sequence arrangements of higher primate alpha-globin duplication units.
复制标题
高等灵长类α-珠蛋白重复单元镶嵌序列排列的分子起源。
DOI：
10.1073/pnas.94.10.5177
复制
发表时间：
1997
影响因子：
11.1
通讯作者：
Shen,CK
中科院分区：
文献类型：
--
作者：
Bailey,AD;Shen,CC;Shen,CK
成人α-珠蛋白基因座由三对同源区（X、Y和Z）和三个非同源区（I、II和III）以及三个重复序列组成。有人认为，一个古老的灵长类α-珠蛋白单位是X、Y和Z以及α 1/α 2重复序列的祖先。然而，这三个非同源块体的进化起源仍然不清楚。我们现在已经分析了长臂猿（Hylobates lar）整个成体α-珠蛋白基因座的序列组织。与人I区同源的DNA片段出现在γ-α-珠蛋白基因座的两个复制单位中。详细的物种间序列比较表明，非同源的模块I和II，以及另一个序列IV，都是祖先的α-珠蛋白包含单位之前，它的串联复制的一部分。然而，此后的某个时候，在人和豚鼠中，从含人α1-球蛋白的单元中删除了I区，并且从含α2-球蛋白的单元中也删除了II区。这些可能是独立的事件都介导的独立的非法重组过程。有趣的是，这些缺失的终点与p53家族重复序列的潜在插入位点相吻合。这些结果表明，在真核生物基因组中的DNA片段的形成涉及的DNA重复元件的逆转录结合简单的DNA重组过程。
The human adult α-globin locus consists of three pairs of homology blocks (X, Y, and Z) interspersed with three nonhomology blocks (I, II, and III), and threeAlufamily repeats,Alu1, Alu2, andAlu3. It has been suggested that an ancient primate α-globin-containing unit was ancestral to the X, Y, and Z and theAlu1/Alu2repeats. However, the evolutionary origin of the three nonhomologous blocks has remained obscure. We have now analyzed the sequence organization of the entire adult α-globin locus of gibbon (Hylobates lar). DNA segments homologous to human block I occur in both duplication units of the gibbon α-globin locus. Detailed interspecies sequence comparisons suggest that nonhomologous blocks I and II, as well as another sequence, IV, were all part of the ancestral α-globin-containing unit prior to its tandem duplication. However, sometime thereafter, block I was deleted from the human α1-globin-containing unit, and block II was also deleted from the α2-globin-containing unit in both human and gibbon. These were probably independent events both mediated by independent illegitimate recombination processes. Interestingly, the end points of these deletions coincide with potential insertion sites ofAlufamily repeats. These results suggest that the shaping of DNA segments in eukaryotic genomes involved the retroposition of repetitive DNA elements in conjunction with simple DNA recombination processes.