Chung Ho-Ryun, Löhr Ulrike, Jäckle Herbert
Max-Planck-Institut für biophysikalische Chemie, Abteilung Molekulare Entwicklungsbiologie, Am Fassberg 11, 37077 Göttingen, Germany.
Mol Biol Evol. 2007 Sep;24(9):1934-43. doi: 10.1093/molbev/msm121. Epub 2007 Jun 14.
The zinc finger associated domain (ZAD), present in almost 100 distinct proteins, characterizes the largest subgroup of C2H2 zinc finger proteins in Drosophila melanogaster and was initially found to be encoded by arthropod genomes only. Here, we report that the ZAD was also present in the last common ancestor of arthropods and vertebrates, and that vertebrate genomes contain a single conserved gene that codes for a ZAD-like peptide. Comparison of the ZAD proteomes of several arthropod species revealed an extensive and species-specific expansion of ZAD-coding genes in higher holometabolous insects, and shows that only few ZAD-coding genes with essential functions in Drosophila melanogaster are conserved. Furthermore, at least 50% of the ZAD-coding genes of Drosophila melanogaster are expressed in the female germline, suggesting a function in oocyte development and/or a requirement during early embryogenesis. Since the majority of the essential ZAD coding genes of Drosophila melanogaster were not conserved during arthropod or at least during insect evolution, we propose that the LSE of ZAD-coding genes shown here may provide the raw material for the evolution of new functions that allow organisms to pursue novel evolutionary paths.
锌指相关结构域（ZAD）存在于近100种不同的蛋白质中，是黑腹果蝇中C2H2锌指蛋白最大的亚组的特征，最初发现仅由节肢动物基因组编码。在此，我们报告ZAD也存在于节肢动物和脊椎动物的最后一个共同祖先中，并且脊椎动物基因组包含一个编码ZAD样肽的单一保守基因。对几种节肢动物物种的ZAD蛋白质组的比较揭示了在高等全变态昆虫中ZAD编码基因的广泛且物种特异性的扩展，并表明在黑腹果蝇中仅少数具有基本功能的ZAD编码基因是保守的。此外，黑腹果蝇至少50%的ZAD编码基因在雌性生殖系中表达，这表明其在卵母细胞发育中的功能和/或早期胚胎发生过程中的需求。由于黑腹果蝇中大多数必需的ZAD编码基因在节肢动物进化过程中或至少在昆虫进化过程中未被保留，我们提出此处所示的ZAD编码基因的大规模物种特异性扩展可能为新功能的进化提供原材料，使生物体能够走上新的进化道路。
