Structurally related Arabidopsis ANGUSTIFOLIA is functionally distinct from the transcriptional corepressor CtBP
Structurally related Arabidopsis ANGUSTIFOLIA is functionally distinct from the transcriptional corepressor CtBP
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DOI：
10.1007/s00427-007-0186-8
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发表时间：
2007-12-01
影响因子：
2.4
通讯作者：
Nibu, Yutaka
中科院分区：
文献类型：
--
作者：
Stern, Mark D.;Aihara, Hitoshi;Nibu, Yutaka
ANGUSTIFOLIA (AN) 控制拟南芥植物的叶子形态。先前的序列相似性研究表明，与 AN 最接近的蛋白质是在线虫、节肢动物和脊椎动物中发现的动物 C 末端结合蛋白 (CtBP) 的成员。果蝇 CtBP (dCtBP) 作为含有短氨基酸基序 PXDLS 的脱氧核糖核酸 (DNA) 结合抑制子的转录辅抑制子，在早期胚胎发生过程中调节组织规范和分割。此前已有研究表明，AN 被认为可以抑制转录，其功能与 CtBP 的功能类似；然而，AN 缺乏动物 CtBP 中保守的一些结构特征。在本文中，我们研究了 AN 是否与 dCtBP 在功能上相关。首先，我们重新检查了动植物界几个代表性物种的 AN 和各种 CtBP 之间的序列相似性。其次，酵母双杂交测定表明，AN 无法与真正的 CtBP 相互作用因子（带有 PXDLS 基序的腺病毒 E1A 癌蛋白）相互作用。第三，与 DNA 相连的 AN 无法抑制转基因果蝇胚胎中报告基因的表达。第四，过表达测定表明 dCtBP 和 AN 在果蝇组织中的功能不同。最终，AN 未能挽救 dCtBP 功能丧失导致的合子致死。这些数据综合起来表明 AN 在功能上与 dCtBP 不同。很可能，祖先CtBP在动植物分化之后、原口动物-后口动物分裂之前获得了辅阻遏物功能（抑制以及与含有PXDLS基序的阻遏物结合的能力）。因此，我们建议将 AN 归类为 CtBP/BARS/RIBEYE/AN 超家族中的一个亚家族成员。
ANGUSTIFOLIA (AN) controls leaf morphology in the plant Arabidopsis thaliana. Previous studies on sequence similarity demonstrated that the closest proteins to AN are members of animal C-terminal-binding proteins (CtBPs) found in nematodes, arthropods, and vertebrates. Drosophila CtBP (dCtBP) functions as a transcriptional corepressor for deoxyribonucleic acid (DNA)-binding repressors containing the short amino acid motif, PXDLS, to regulate tissue specification and segmentation during early embryogenesis. It has previously been shown that AN was thought to repress transcription similar to the function of CtBPs; however, AN lacks some of the structural features that are conserved in animal CtBPs. In this paper, we examined whether AN is functionally related to dCtBP. Firstly, we re-examined sequence similarity among AN and various CtBPs from several representative species in the plant and animal kingdoms. Secondly, yeast two-hybrid assays demonstrated that AN failed to interact with an authentic CtBP-interacting factor, adenovirus E1A oncoprotein bearing the PXDLS motif. Thirdly, AN tethered to DNA was unable to repress the expression of reporter genes in transgenic Drosophila embryos. Fourthly, overexpression assays suggested that dCtBP and AN function differently in Drosophila tissues. Finally, AN failed to rescue the zygotic lethality caused by dCtBP loss-of-function. These data, taken together, suggest that AN is functionally distinct from dCtBP. Likely, ancestral CtBPs acquired corepressor function (capability of both repression and binding to repressors containing the PXDLS motif) after the animal-plant divergence but before the protostome-deuterostome split. We therefore propose to categorize AN as a subfamily member within the CtBP/BARS/RIBEYE/AN superfamily.