Rapid coevolution of the nematode sex-determining genes fem-3 and tra-2
Rapid coevolution of the nematode sex-determining genes fem-3 and tra-2
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DOI：
10.1016/s0960-9822(02)01333-7
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发表时间：
2002-12-10
期刊：
影响因子：
9.2
通讯作者：
Kimble, J
中科院分区：
文献类型：
--
作者：
Haag, ES;Wang, SP;Kimble, J
与后生动物发育的许多特征不同，性别决定在门中并不广泛保守[1-3]。然而，最近的研究表明，一个基因家族控制着果蝇的性发育。线虫和脊椎动物的研究表明，性别决定机制可能是从一个共同的途径进化而来的，而这个途径自寒武纪以来就已经发生了根本性的分歧。性别决定基因序列经常快速进化（例如，[5，69 7]），但目前还不知道这与更高级的途径有何关系，也不知道是什么选择或中性力量在驱动它。在这样一个快速进化的发育途径中，功能相关基因的命运特别令人感兴趣。为了研究一对这样的基因，我们克隆了关键C。elegans雄性启动基因fem-3，来自两个姐妹种，C. briggsae和C. remanei。我们采用RNA干扰表明，在所有三个物种中，男性促进功能的fem-3和上位关系，其女性促进上游阻遏物，tra-2，是保守的。与此相一致，FEM-3蛋白在每个物种中与TRA-2相互作用，但以严格的物种特异性方式相互作用。由于FEM-3是小杆线虫中描述的最不同的蛋白质，并且TRA-2的FEM-3结合结构域本身是高变的[8，9]，因此关键的蛋白质-蛋白质相互作用正在快速地协同进化。将这一结果外推到更大的系统发育尺度有助于解释不同门的性别决定系统的差异。
Unlike many features of metazoan development, sex determination is not widely conserved among phyla [1-3]. However, the recent demonstration [4] that one gene family controls sexual development in Drosophila, C. elegans, and vertebrates suggests that sex determination mechanisms may have evolved from a common pathway that has diverged radically since the Cambrian. Sex determination gene sequences often evolve quickly (e.g., [5, 69 7]), but it is not known how this relates to higher-order pathways or what selective or neutral forces are driving it. In such a rapidly evolving developmental pathway, the fate of functionally linked genes is of particular interest. To investigate a pair of such genes, we cloned orthologs of the key C. elegans male-promoting gene fem-3 from two sister species, C. briggsae and C. remanei. We employed RNA interference to show that in all three species, the male-promoting function of fem-3 and its epistatic relationship with its female-promoting upstream repressor, tra-2, are conserved. Consistent with this, the FEM-3 protein interacts with TRA-2 in each species, but in a strictly species-specific manner. Because FEM-3 is the most divergent protein yet described in Caenorhabditis and the FEM-3 binding domain of TRA-2 is itself hypervariable [8, 9], a key protein-protein interaction is rapidly evolving in concert. Extrapolation of this result to larger phylogenetic scales helps explain the dissimilarity of the sex determination systems across phyla.