AN EVOLUTIONARY MODEL FOR THE DUPLICATION AND DIVERGENCE OF ESTERASE GENES IN DROSOPHILA
AN EVOLUTIONARY MODEL FOR THE DUPLICATION AND DIVERGENCE OF ESTERASE GENES IN DROSOPHILA
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DOI：
10.1007/bf00160464
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发表时间：
1992-06-01
影响因子：
3.9
通讯作者：
RICHMOND, RC
中科院分区：
文献类型：
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作者：
BRADY, JP;RICHMOND, RC
拟暗果蝇中的酯酶5（Est-5 =基因，EST 5 =蛋白质）酶由紧密聚集在X染色体右臂上的三个旁系同源基因Est-5A、Est-5 B和Est-5C中的一个编码。果蝇Est-6基因座只有一个旁系同源的邻居Est-P。pseudobscura和两个D. melanogaster基因表明在D. pseudoobscura，D. melanogaster，随后在D.伪暗三个D. pseudobscura基因在成对比较中显示出78-85%的相似性，而Est-6和Est-P之间的相关性仅为67%。D. pseudobscura可能由Est-5 B和Est-5C的相对较新的分歧以及Est-5A和Est-5 B之间可能的基因转换事件引起。在每个物种的旁系同源基因和直系同源基因的两个外显子的沉默和替换位点的差异分析表明，共同的选择力作用于所有五个位点。常见的净化选择性约束的进一步证据来自亲水性剖面和拟议的催化残留物的保护。然而，在D. melanogaster相对于D. pseudobscura表明，种间差异的选择也存在。
The esterase 5 (Est-5 = gene, EST 5 = protein) enzyme in Drosophila pseudoobscura is encoded by one of three paralogous genes, Est-5A, Est-5B, and Est-5C, that are tightly clustered on the right arm of the X chromosome. The homologous Est-6 locus in Drosophila melanogaster has only one paralogous neighbor, Est-P. Comparisons of coding and flanking DNA sequences among the three D. pseudoobscura and two D. melanogaster genes suggest that two paralogous genes were present before the divergence of D. pseudoobscura from D. melanogaster and that, later, a second duplication occurred in D. pseudoobscura. Nucleotide sequences of the coding regions of the three D. pseudoobscura genes showed 78-85% similarity in pairwise comparisons, whereas the relatedness between Est-6 and Est-P was only 67%. The higher degree of conservation in D. pseudoobscura likely results from the comparatively recent divergence of Est-5B and Est-5C and from possible gene conversion events between Est-5A and Est-5B. Analyses of silent and replacement site differences in the two exons of the paralogous and orthologous genes in each species indicate that common selective forces are acting on all five loci. Further evidence for common purifying selective constraints comes from the conservation of hydropathy profiles and proposed catalytic residues. However, different levels of amino acid substitution between the paralogous genes in D. melanogaster relative to those in D. pseudoobscura suggest that interspecific differences in selection also exist.