Gross C T, McGinnis W
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA.
EMBO J. 1996 Apr 15;15(8):1961-70.
A 120 bp homeotic response element that is regulated specifically by Deformed in Drosophila embryos contains a single binding site for Deformed protein. However, a 24 bp sub-element containing this site does not constitute a Deformed response element. Specific activation requires a second region in the 120 bp element, which presumably contains one or more binding sites for Deformed cofactors. We have isolated a novel protein from Drosophila nuclear extracts which binds specifically to a site in this second region. This protein, which we call DEAF-1 (Deformed epidermal autoregulatory factor-1), contains three conserved domains. One of these includes a cysteine repeat motif that is similar to a motif found in Drosophila Nervy and the human MTG8 proto-oncoprotein, and another matches a region of Drosophila Trithorax. Mutations in the response element designed to improve binding to DEAF-1 in vitro resulted in increased embryonic expression. Conversely, small mutations designed to diminish binding to DEAF-1 resulted in reduced expression of the element. Thus, DEAF-1 is likely to contribute to the functional activity, and perhaps to the homeotic specificity, of this response element. Consistent with this hypothesis, we have discovered DEAF-1 binding sites in other Deformed response elements.
在果蝇胚胎中受畸形基因特异性调控的一个120 bp的同源异型反应元件含有一个畸形蛋白的单一结合位点。然而，包含该位点的一个24 bp子元件并不构成一个畸形反应元件。特异性激活需要120 bp元件中的第二个区域，该区域可能含有一个或多个畸形辅因子的结合位点。我们从果蝇核提取物中分离出一种新型蛋白质，它能特异性结合到这个第二个区域的一个位点上。这种蛋白质，我们称之为DEAF-1（畸形表皮自调节因子-1），含有三个保守结构域。其中一个结构域包括一个半胱氨酸重复基序，它类似于在果蝇Nervy和人类MTG8原癌蛋白中发现的一个基序，另一个与果蝇三体胸蛋白的一个区域匹配。在体外设计用于改善与DEAF-1结合的反应元件中的突变导致胚胎表达增加。相反，设计用于减少与DEAF-1结合的小突变导致该元件的表达降低。因此，DEAF-1可能有助于这个反应元件的功能活性，也许还有助于同源异型特异性。与这个假设一致，我们在其他畸形反应元件中发现了DEAF-1结合位点。
