Abdel-Hafiz H A, Chen C Y, Marcell T, Kroll D J, Hoeffler J P
Department of Medicine, University of Colorado School of Medicine, Denver 80262.
Oncogene. 1993 May;8(5):1161-74.
Dimerization of leucine zipper-containing proteins has been associated characteristically with the formation of a coiled-coil structure between two compatible leucine zipper motifs. In the present study we demonstrate the association of the leucine zipper of cAMP response element-binding protein (CREB) with a zinc finger motif of ATF-2. The association of the CREB leucine zipper with the ATF-2 zinc finger is stabilized if the ATF-2 leucine zipper is intact, implying that the preferred interactive structure of ATF-2 juxtaposes the amino-terminal zinc finger motif of this protein with the carboxy-terminal leucine zipper of this same protein. Furthermore, we demonstrate that the association of the CREB leucine zipper with the ATF-2 zinc finger in vitro blocks the association of the adenoviral E1a protein with ATF-2. Similarly, overexpression of full-length CREB, or a truncated version of this protein corresponding to the carboxy-terminal 74 amino acids that make up the DNA-binding and dimerization domains, can block the ATF-2-mediated transcriptional stimulation by E1a in vivo. Mutation of the ATF-2 zinc finger motif stimulates DNA binding of this protein, and abolishes interactions with E1a and CREB proteins. These results demonstrate that the structural conformation of ATF-2 is critical for DNA binding and protein-protein interactions and, further, that leucine zippers can mediate protein-protein interactions with structural motifs other than leucine zippers.
含亮氨酸拉链的蛋白质二聚化通常与两个相容的亮氨酸拉链基序之间形成卷曲螺旋结构有关。在本研究中，我们证明了环磷酸腺苷反应元件结合蛋白（CREB）的亮氨酸拉链与ATF-2的锌指基序相关联。如果ATF-2的亮氨酸拉链完整，则CREB亮氨酸拉链与ATF-2锌指的关联会得到稳定，这意味着ATF-2的优选相互作用结构将该蛋白质的氨基末端锌指基序与同一蛋白质的羧基末端亮氨酸拉链并列。此外，我们证明，CREB亮氨酸拉链与ATF-2锌指在体外的关联会阻断腺病毒E1a蛋白与ATF-2的关联。同样，全长CREB或该蛋白质的截短版本（对应于构成DNA结合和二聚化结构域的羧基末端74个氨基酸）的过表达可以在体内阻断E1a介导的ATF-2转录刺激。ATF-2锌指基序的突变会刺激该蛋白质的DNA结合，并消除与E1a和CREB蛋白的相互作用。这些结果表明，ATF-2的结构构象对于DNA结合和蛋白质-蛋白质相互作用至关重要，此外，亮氨酸拉链可以介导与亮氨酸拉链以外的结构基序的蛋白质-蛋白质相互作用。
